"NBI Colliderscope";"Clive Ellegaard";"2010-01-08";"17:00";"";"";"Foran Bygning C, Blegdamsvej 17, 2100 København Ø";"Lysshow pÃ¥ Bygning C fredag aften ";" Du/I inviteres hermed til indvielsen af NBI Colliderscope NBI Colliderscope er en lysinstallation pÃ¥ facaden af Niels Bohr Institutets hovedbygning. Installationen er direkte forbundet til verdens største fysik eksperiment, der netop er begyndt i LHC acceleratoren i CERN i Schweiz. Colliderscopet fremviser en intuitiv visuel oversættelse af begivenhederne i acceleratorens indre. Værket er skabt af fysikeren Clive Ellegaard og billedkunstnerne Skeel og Skriver Bearbejdningen af data fra Atlas detektoren er foretaget i samarbejde med Troels C. Petersen fra Discovery Centret ved NBI. Computerprogrammering er udført af Anders Holm. Værket er støttet af: Kunststyrelsen Velux fonden Niels Bohr Fonden NBI Colliderscope er en satellitudstilling fra Esbjerg Kunstmuseum www.colliderscope.nbi.dk "
"Feasibility of Bell tests with the W state";"Eugene Polzik";"2010-01-11";"13:15";"";"";"Quantop Lounge";"Talk by Amine Laghaout, Royal Institute of Technology (KTH) ";" Entanglement of multi-qubit systems is central to quantum information and communication. It can also be of interest from a theoretical perspective in furthering tests of non-locality. An experimental scheme for such tests will be presented using the tripartite W state, whereby a single photon is entangled with two vacuum modes. The challenge, however, is that the characterization of such Fock-state qubits requires measurements in non-commuting bases. A theoretical method for performing such polyvalent projective measurements in will be worked out. Ultimately, the goal of the analysis is to assess whether Bell tests with the W are feasible given the actual performance of photodetection devices. "
"Joint HET-DARK-DISCOVERY Seminar";"P.H. Damgaard";"2010-01-14";"14:15";"";"";"Aud. D, Blv.";"Federico Urban, University of British Columbia ";" Speaker: Federico Urban, University of British Columbia Title: The QCD nature of Dark Energy, signatures and applications Abstract: The origin of the observed dark energy could be explained entirely within the standard model, with no new fields required. I will review the ideas underlying the appearance of the Veneziano ghost of low-energy QCD and show how nontrivial spacetimes (compact topologies and time-dependent background) give rise to interesting new effects such as Casimir energies and gravitational production of unphysical states. I will then discuss the cosmological applications of such effects (dark energy, generation of primordial magnetic fields). "
"Copenhagen-Harvard Quantum Science Workshop";"Charles Marcus";"2010-01-19";"";"2010-01-21";"";"Niels Bohr Institute (Blegdamsvej and Nano-Science Center)";"This week a group from Harvard visit Nano-Science Center ";"Day One (Tuesday, Jan. 19th) Blegdamsvej 17 (Auditorium M): Welcome: Charles Marcus 3:20-3:25 PM Eran Kot - Quantum Optics Theory (topic TBA) - 3:30-3:55 PM Michael James Kastoryano - Dissipative Bell state preparation in a Cavity - 4:00-4:25 PM Hugh Churchill - Nanotube spintronics - 4:30-4:55 PM Coffee Break - 4:55-5:15 PM (""Little lunchroom"" in building F) Maja Cassidy - Si Nanoparticles for Hyperpolarized Magnetic Resonance Imaging - 5:20-5:45 PM Hanna Krauter - Quantum information processing with spin polarized atoms.Talk 5:50 - 6:15 PM Daniel Oblak - Entanglement assisted atom clock Talk 6:20 - 6:45 PM Quantum Optics Lab Tour 6:50 - 7:30 PM Day Two (Wednesday, Jan. 20th) HCØ, Universitetsparken 5 (Auditorium 7): Christian Barthel - Hyperfine interaction in GaAs quantum dots - 3:30-3:55 PM Jim Medford - Dynamical Decoupling in decoherence in spin qubits - 4:00-4:25 PM Andres Reynoso- 4:30-4:55 PM Coffee Break - 4:55-5:15 PM (outside auditorium) Jakob Kryger Sørensen - Molecular Electronics - 5:20-5:45 PM Titoo Jain - Molecular Electronics - 5:50 - 6:15 PM Martin Leijnse - Condensed Matter Theory - 6:20 - 6:45 PM Molecular Electronics Lab Tour - 6:50 - 7:30 PM Day Three (Thursday Jan. 21) HCØ, Universitetsparken 5 (Auditorium 8): Thomas Jespersen - Nanotube Electronics - 3:30-3:55 PM Kasper Grove-Rasmussen - Nanotube Electronics - 4:00-4:25 PM Patrick Herring - Fabrication of Nanotube Nanoelectronic Devices - 4:30-4:55 PM Coffee Break - 4:55-5:15 PM (outside auditorium) Ferdinand Kuemmeth - Transport in Si/Ge Nanowires - 5:20-5:45 PM Doug McClure - Interferometry in the Quantum Hall Regime - 5:50 - 6:15 PM Angela Kou - Dynamic Nuclear Polarization in the Fractional Quantum Hall Regime - 6:20 - 6:45 PM Verena Koerting - Cotunneling transport 6:50 - 7:15 PM Nanoelectronics Lab Tour - 7:20 - 7:55 PM "
"An ion crystal quantum repeater";"Anders Sørensen";"2010-01-22";"13.15";"";"";"Aud. M";"Master´s thesis defence J. M. Petersen, NBI ";" An important goal of quantum information science is reliable quantum communication. This is a serious challenge given the rapid decoherence of quantum systems. A possible way forward is to use so-called quantum repeaters to distribute entanglement between the sender and the receiver and a promising scheme is the DLCZ repeater (1) which uses ensembles of atoms for the entanglement distribution. Ion Coulomb crystals (2) are attractive ensembles for the DLCZ repeater since they have the potential to be good quantum memories and they couple well to light when put in an optical cavity. In this master's thesis defence we present a detailed calculation of the quantum repeater's so-called write-in interaction in an ion crystal in a standing wave cavity. The combination of the standing wave and the thermal movement of the individual ions is shown to destroy the write-in. A possible solution to the problem is given in the form of moving the whole crystal during the interaction with light. Then, we calculate the so-called read-out interaction and again try to solve the problem of the standing wave by fast displacement of the crystal. "
"Spontaneous emission in light-atom interactions for atomic ensembles";"Anders Sørensen";"2010-01-22";"15:00";"";"";"Aud. M";"Master's thesis defence Nikolaj Korolev, NBI ";"In my thesis I have reviewed the Faraday interaction between a coherent light field and an atomic ensemble. The Faraday interaction is an important tool in the growing field of quantum information, which is widely used to perform quantum memory protocols. At the Niels Bohr Institute, Eugene Polzik's group has had succes with performing the direct mapping protocol based on the Faraday interaction. However so far there has not been a satisfactory description of the spontaneous emission that the system undergoes. In this work there is included the full level structure of the atoms and obtained a complete description of the decoherence from spontaneous emission. "
"Joint HET-DARK-DISCOVERY Seminar";"E. Bjerrum-Bohr";"2010-01-26";"13.15 ";"";"";"Aud. A. Blv";"Martin S. Sloth, CERN (please note unusual time) ";" Speaker: Martin S. Sloth Title: Cosmological perturbations and the stability of de Sitter Abstract: Inflation together with cosmological perturbation theory is very successful in explaining the origin of structure and the CMB anisotropies. However, at higher orders there are notorious infrared issues plaguing perturbation theory in inflationary (quasi) de Sitter space-times. We will discuss what we can learn about the stability of de Sitter from non-linear cosmological perturbations and the other way around. "
"Stripe order and pairing the Cuprate Superconductors";"Brian Møller Andersen";"2010-01-28";"11:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D203";"Speaker: Mats Granath, University of Gothenburg ";"Abstract: Evidence is mounting that electronic ""stripe"" order with broken lattice rotational and translational symmetry is a ubiquitous feature of the copper-oxide high-temperature superconductors. I review some of the evidence for such electronic phases and discuss their possible relevance to superconductivity in these materials. I will also mention some recent work that explores stripe pair correlations to make connections to experimental observations from angle resolved photoemission and scanning tunneling spectroscopy. Speaker: Mats Granath, University of Gothenburg "
"Entanglement and metrology in hybrid quantum systems";"Charles Marcus/Anders S. Sørensen";"2010-01-29";"13:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D317";"Talk by Jake Taylor, Joint Quantum Institute/NIST ";" Talk by Jake Taylor , Joint Quantum Institute/NIST: ""Entanglement and metrology in hybrid quantum systems"" "
"Talk by Pierre Lemonde, L'Observatoire astronomique de Paris-Meudon-Nancay ";"Eugene Polzik";"2010-02-01";"10:15";"";"";"Aud A";"Optical frequency metrology at Laboratoire national de métrologie et d'essais - Système de Références Temps-Espace (LNE-SYRTE) ";"Research on optical frequency metrology at LNE-SYRTE presently follow three different directions. First, on optical atomic clocks, I will present recent results on two projects towards high performance optical lattice clocks with Sr and Hg atoms. In particular, I will focus on the optimization of the clocks frequency stability and associated experimental developments- non-destructive detection scheme and ultra-stable laser. Second, on long distance clock comparison, I will describe a high performance coherent optical fiber link and preliminary results towards a free-space coherent optical link. Finally, I will show recent results on the generation of microwave signals with stability close to 10^{-16} at 1s averaging time by downconversion of an optical source using a fiber femto-second frequency comb. "
"Quantum State Engineering in Cold Caesium Atoms: An entangled tale of non-destructively induced collapse and squeezing of quantum states.";"Eugene Polzik";"2010-02-01";"14:00";"";"";"Aud A";"PhD Defence, Daniel Oblak ";" Quantum mechanics is characterised by several strange features, which include quantum uncertainty, quantum measurements, and entanglement. This thesis involves all three of these. The quantum uncertainty poses a fundamental standard quantum limit (SQL) in applications where quantum systems are used to gauge some quantity. A prime example is that of atomic frequency standards, which with unprecedented precision measure an atomic quantum state. Quantum measurements in the form of Quantum Non-Demolition (QND) measurements can be engineered so as to overcome the SQL by redistributing quantum uncertainty amongst different variables of the system. Such squeezed spin-states rely on inter-atomic correlation, which goes by the name of entanglement.In this work we present a detailed description of how we have implemented a QND measurement with laser pulses in a Mach-Zehnder Interferometer (MZI) and demonstrate that we can engineer a squeezed state in a cold trapped ensemble of Cs atoms. We verify that the squeezing is useful for improving the precision of atomic clocks. Along the way, we also investigate several remarkable features of the interaction, by which atoms and light-particles (photons) exchange phase-shifts. After the questioning by the opponents, approximately at 4 pm, a reception will be held in the institute cantine. "
"Nanofiber Photonics and Quantum Optics";"Eugene Polzik";"2010-02-02";"10:15";"";"";"Aud. A";"Talk by Arno Rauschenbeutel, University of Mainz ";"Recently, optical nanofibers with diameters smaller than the wavelength of the guided light have attracted considerable interest in the field of quantum optics due to their high potential for efficiently interfacing light and matter. In my talk I will report on two experiments using such nanofiber-optical interfaces. In the first experiment, we perform ultra-sensitive spectroscopic measurements on 3,4,9,10-perylene-tetracarboxylic dianhydride molecules (PTCDA) deposited on the fiber surface at ambient conditions. We use the guided mode of the nanofiber both for excitation of the molecules and for fluorescence collection and we show that surface coverages as small as 1 ‰ of a compact monolayer still give rise to absorption and fluorescence spectra with a good signal to noise ratio. In the second experiment, we trap about 2000 cold neutral cesium atoms close to the surface of an optical nanofiber using the optical dipole force exerted by the evanescent field of the nanofiber guided light. The atoms are probed with a weak resonant field which is sent through the nanofiber and which interfaces with the atoms via the evanescent field. Remarkably, the atomic ensemble almost entirely absorbs this probe field, yielding an optical depth of up to 18. This opens the route towards non-linear optics and quantum communication applications with fiber-coupled atomic ensembles. "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-02-04";"15:00";"";"";"Aud. D, Blegdamsvej 17";"Thermal Transport and Energy Loss in Non-critical Holographic QCD, Umut Gürsoy (Utrecht) ";" Umut Gürsoy (Utrecht) Title: Thermal Transport and Energy Loss in Non-critical Holographic QCD Abstract: I will present a phenomenological holographic model for the Quark-gluon plasma, that captures the realistic effects such as the running of the gauge coupling. We study real-time phenomena such as the transport and energy-loss of heavy quarks at finite temperature, by means of the holographic model. "
"PhD Defence, Brian Bak Jensen, NBI ";"Jan W. Thomsen";"2010-02-05";"14:00";"";"";"Aud 5, HCØ";"Production and Interrogation of Metastable Magnesium Atoms: Toward an Atomic Clock ";" The concept of time and measurement of time plays a unique role in modern physics and technology. For example is the meter defined today as the distance light travels in vacuum in 1/299.792.148 seconds. Equally so does a lot of practical applications depend on precise measurement of time. It can here be mentioned the GPS system, Mobile communication and navigation in space. All of these are dependent on atomic clocks, that is clocks where the electron act as a precise pendulum. At the Niels Bohr Institute we are working on a super precise atomic clock based on magnesium atoms. For example has magnesium some of the longest lived atomic states that connect the ground state with higher lying metastable states. With the help of frequency stabilized lasers, it has been made possible to measure the lifetime of some of the metastable states. For example has the first measurement of the lifetime of the 3P2 state been measured. The 3P2 state has a lifetime of 2000 seconds and is amongst the most long lived atomic states which makes it interesting for atomic clock purposes. The frequency stabilization of the lasers to an atomic transition has made it possible not only to lock the lasers in frequency but also to determine atomic properties of magnesium atoms. "
"Theoretical High Energy Seminar";"Marta Orselli";"2010-02-09";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"S-matrix of Pohlmeyer reduced form of AdS_5 x S^5 superstring theory, Arkady Tseytlin (Imperial College) ";" Arkady Tseytlin (Imperial College) Title: S-matrix of Pohlmeyer reduced form of AdS_5 x S^5 superstring theory Abstract: With a motivation to find a 2-d Lorentz-invariant solution of the AdS_5 x S^5 superstring we shall consider the Pohlmeyer-reduced form of this theory. The reduced theory is constructed from currents of the superstring sigma model and is classically equivalent to it. Its action is that of Sp(2,2)xSp(4)/SU(2)^4 gauged WZW model deformed by an integrable potential and coupled to fermions. This theory is UV finite and is conjectured to be related to the superstring theory also at the quantum level. Since the theory is integrable, its S-matrix should be effectively determined by the two-particle scattering. We compute the tree-level two-particle S-matrix for the elementary excitations of the reduced theory and find that this S-matrix has the same index structure and group factorization properties as the superstring S-matrix. We discuss possible relation between the two S-matrices. "
"NBA History of Science Seminar";"Niels Bohr Archive";"2010-02-11";"14:15";"";"";"Aud. A, Niels Bohr Institute, Blegdamsvej 17";"Christian Gram: Early History of Computers in Denmark – a personal view ";" Christian Gram, Regnecentralen (1962 - 1973), DTU (1973 - 2000) Early History of Computers in Denmark – a personal view http://www.nba.nbi.dk/files/sem/11feb10.html "
"Master thesis Thomas Alsbirk";"Aksel Walløe Hansen";"2010-02-11";"14:15";"";"";"lk. 71, Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"The South West African Low-Level Coastal Jet ";" The South West African Low-Level Coastal Jet -a general study of the South West African Low-level Jet and a numerical Galathea 3 case-study of topography and SST as forcings on the Jet structure The talk will be in danish Supervisor: Aksel Walløe Hansen, NBI "
"Midtvejs Kollokvium: Stud Scient Henning Gisselø";"Aksel Walløe Hansen";"2010-02-12";"13:15";"";"";"Lk. 061 Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"Aerosolers effekt pÃ¥ sigtbarhedsberegningen i HIRLAM ";"Aerosolers effekt pÃ¥ sigtbarhedsberegningen i HIRLAM Nedsat sigtbarhed (især tÃ¥ge; sigtbarhed < 1000 m) har store sikkerhedsmæssige og økonomiske konsekvenser for afvikling af især flytrafik, men ogsÃ¥ bil- og skibstrafik pÃ¥virkes. I den operationelle vejrmodel (HIRLAM) har selv smÃ¥ ændringer i temperatur og fugtighed stor betydning for sigtbarhedsberegningen, og det har den konsekvens, at modellen i nogle tilfælde er for hurtig til at forudsige tÃ¥gedannelse og -opløsning. En alternativ parameterisering af sigtbarhed er foreslÃ¥et af Gultepe et al. (2007) : Visibility = (LWC ∙ Nd )-0.65, hvor LWC (Liquid Water Content) er luftens indhold af flydende vand og Nd er antallet af skydrÃ¥ber pr. volumenenhed. Projektet har til formÃ¥l at teste ovennævnte parameterisering i en 1-D version af HIRLAM. Et forøget aerosolindhold giver flere og mindre skydrÃ¥ber. Den 1. indirekte aerosoleffekt, som beskriver en forøget refleksion af kortbølget strÃ¥ling fra skyer med flere og mindre drÃ¥ber drevet af tilstedeværelsen af aerosoler, er blevet implementeret i 1-D modellen. En større refleksion af kortbølget strÃ¥ling i tÃ¥gelaget forventes at ville dæmpe opvarmningen af det nederste lag i troposfæren, hvilket igen kan forsinke en opløsning af tÃ¥gelaget. NÃ¥r Nd perturberes kan man registrere en effekt i bÃ¥de sigtbarhed, LWC og overfladetemperaturen. Næste skridt bliver at teste parameteriseringen i 3-D. "
"Theoretical High Energy Seminar";"H. B. Nielsen";"2010-02-16";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"Dark matter, an exotic bound state, and the Tunguska event, C. D. Froggatt (University of Glasgow) ";" C. D. Froggatt (University of Glasgow) Title: Dark matter, an exotic bound state, and the Tunguska event "
"PhD defence Henriette Skourup";"Christine S. Hvidberg";"2010-02-19";"13:15";"";"";"Auditoriet, NBI, Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"A study of Arctic sea ice freeboard heights, gravity anomalies and dynamic topography from ICESat measurements ";" A study of Arctic sea ice freeboard heights, gravity anomalies and dynamic topography from ICESat measurements Abstract: The Arctic sea ice cover has a great influence on the climate and responds rapidly to climate changes. Thus, observations of the state of the sea ice cover will provide invaluable input to existing climate models. Since 2003 the Ice, Cloud and land Elevation Satellite (ICESat) laser altimetry mission has provided satellite altimetry over the ice covered Arctic Ocean up to 86˚N. In this thesis, the main topic is to estimate the sea surface height in the Arctic Ocean from ICESat laser altimetry data and to use this information to estimate sea ice freeboard heights (the part of the ice above the sea surface), the large scale ocean circulation, as well as the gravity field. Abstract in Danish: Havisen, der dækker det arktiske ocean, har en stor indflydelse pÃ¥ klimaet og pÃ¥virkes ligeledes hurtigt af klima forandringer. Observationer af havisens tilstand vil sÃ¥ledes bidrage med uvurderlig information til eksisterende klima modeller. Siden 2003 har NASA's satellit ICESat (Ice, Cloud and land Elevation Satellite) observeret jordens overflade op til 86˚N med et laser altimeter. I denne afhandling er hovedformÃ¥let at bestemme havoverfladen i det isdækkede arktiske ocean ved brug af observationerne opsamlet af ICESat's altimeter. Og at anvende denne viden til at bestemme fribordet (højden af isen over havoverfladen), tyngdefeltet samt havets topografi, der afspejler den storskala havcirkulation. Supervisor: Carl Christian Tscherning, Co-supervisor: Rene Forsberg "
"Inaugural lecture by Stefania Xella";"Jens Paaske";"2010-02-24";"13:15";"";"";"Aud. 3, H.C.Ørsted Institute, Universitetsparken 5, 2100 København Ø";"Inaugural lecture by associate professor Stefania Xella, Niels Bohr Institutet ";" Abstract: Unraveling the Hidden Symmetries of Nature After more than twenty years of worldwide effort, and a strong collaboration among physicists from four different continents, the proton-proton Large Hadron Collider at CERN, Switzerland, has begun operation. This starts a new era in particle physics. This new experimental input will help us improve our understanding of the world at its smallest scale, the particle scale. Some of the questions still unanswered are: what is this form of energy we call mass, which all particles seem to have in different amounts? Why forces between particles are so different, as we observe in our world today? In this colloquium I will explain how theoretically we explain such an asymmetric particle world today as a product of a highly symmetric one at some early stage of the Universe, and how we expect to test this theory with the new data collected at the Large Hadron Collider. I will also highlight what my contribution to such an exciting area of research is. "
"Talk by Mark Laver, PSI";"Kim Lefmann";"2010-02-25";"10:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø. D bygningen lokale 411 ";"Scattering from flux lines in superconductors --- from unconventional to conventional, and from lattice to glass ";"The arrangement of flux lines (FLs) in Type-II superconductors can unveil invaluable information about the underlying superconducting state, and by itself the FL system may be exploited as a test-bed for theories of structural order in solids and glasses. In this talk we overview recent results from neutron scattering explorations of FLs in superconductors, ranging from elemental niobium to the pnictides and cuprates. Contemporary theories, such as the 'Bragg glass' --- where quasi-long range order survives in a weakly disordered system --- are examined. Also, the rich variety of astonishing FL lattice shapes exhibited by Nb and YBCO are presented and we discuss what they reveal as to the underlying nature of these conventional and unconventional superconductors. "
"PhD defence Jesper Sjolte";"Centre for Ice and ";"2010-02-26";"13:00";"";"";"Auditoriet, NBI, Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"Modeling of present and Eemian stable water isotopes in precipitation ";"Modeling of present and Eemian stable water isotopes in precipitation. Author: Jesper Sjolte Principal supervisor: Sigfús J. Johnsen, Centre for Ice and Climate. External supervisor: Georg Hoffmann, LSCE/CEA. Abstract The subject of this thesis is the modeling of the isotopic temperature proxies δ18O, δD and deuterium excess in precipitation. Two modeling studies were carried out, one using the regional climate model, and one using a global climate model. In the regional study the model was run for the period 1959 to 2001 using meteorological data and a domain including Greenland and the surrounding North Atlantic. The model was found to reproduce the observed seasonal variability of temperature and precipitation well. In comparison with ice core data from Greenland and observations from coastal stations the model captured a significant part of the winter δ18O signal from most sites. A signature of the North Atlantic Oscillation on the patterns of temperature, δ18O and precipitation was found in agreement with ice core data and observations. For inland Greenland the modeled deuterium excess level is overestimated, particularly during winter. This is probably related to the representation of micro-physics during snow formation. For coastal areas the annual cycle of deuterium excess was captured well by the model. The global climate model was used for three time slice experiments for the warm Eemian interglacial. Present day boundary conditions were used except for the insolation and the SST patterns. The modeled summer temperatures for the Northern Hemisphere were found to match proxy data well, with the large summer insolation anomalies causing warmer summers than for present day. The peak summer anomalies are +6oC for central Greenland. However, the temperature anomalies are considerably smaller and only marginally significant in Antarctica. The modeled δ18O for Greenland follows the tendency of the ice core data in the different time slices, but with underestimated amplitude. For Antarctica the modeled isotopes do not agree with ice core data. The discrepancy between the model output and the ice core data is attributed to the boundary conditions, where changes in ice sheets and vegetation have not been accounted for. The defence will be followed by a reception . "
"Theoretical High Energy Seminar";"Marta Orselli";"2010-03-02";"14:15";"";"";"Aud M, Blegdamsvej ";"Riccardo Ricci (Imperial College) Title:Generalized scaling and integrability from AdS5 x S5 ";" Riccardo Ricci (Imperial College) Title: Generalized scaling and integrability from AdS5 x S5 Abstract: According to AdS/CFT a remarkable correspondence exists between strings in AdS5 x S5 and operators in N=4 SYM. A particularly important case is that of fast-spinning folded closed strings and the so called twist-operators in the gauge theory. This is a remarkable tool for uncovering and checking the detailed structure of the AdS/CFT correspondence and its integrability properties. In this talk I will show how to match the expression of the anomalous dimension of twist operators as computed from the quantum superstring with the result obtained from the Bethe ansatz of SYM. This agreement resolves a long-standing disagreement between gauge and string sides of the AdS/CFT duality and provides a highly nontrivial strong coupling test of SYM integrability. "
"Niels Bohr Lecture by Professor Leonard Feldman";"Jens Paaske";"2010-03-03";"13:15";"";"";"Aud. 3, H.C.Ørsted Institut, Universitetsparken 5, 2100 København Ø";"The Materials Revolution, Niels Bohr Lecture by Professor Leonard Feldman, Rutgers University and Vanderbilt University ";" About the speaker: Prof. Leonard C. Feldman received his Ph.D.in Physics from Rutgers University in 1967. He went on to Bell Labs, where he was a department head for many years, and then to Vanderbilt University, where he became director of the Institute for Nanoscale Science and Engineering. Prof. Feldman returned to Rutgers in 2007, where he now heads the Institute for Advanced Materials, Devices and Nanotechnology and is Vice President for Physical Science and Engineering Partnerships. Prof. Feldman is among the researchers whose discoveries led to the semiconductor revolution due in part to his work on the interface of silicon and silicon dioxide. He has received many awards and is a fellow of the American Physical Society, the American Association for the Advancement of Science and since 1994 also elected member of the Royal Danish Academy of Sciences and Letters. He is one of the most cited scientists in his field and is known as an excellent teacher and mentor with an international reputation as a scientific leader, both in research and in the management of research. Abstract: Modern materials research includes engineering with atoms, the molecule-by-molecule attack of a cancer growth, collecting the sun's energy with nanocrystals, exploiting the quantum world for computing, defining a stem cell by mechanical deformation and bringing the quantum world to the human experience in an ultra-small solid! Extraordinary accomplishments range from Nobel prizes in chemistry and physics to society-changing applications. Currently, the forefront of materials science is at the nano-scale. Advances in nano-scale materials are envisioned as the solution to some of the dominant technological problems facing our world---conservation of energy and environment, water purification and propagating the information revolution. This talk highlights research directed to these advances. "
"Mid-term colloquium, Hjalte Frellesvig ";"Anders Sørensen";"2010-03-03";"kl. 11";"";"";"Aud. M";"Spin-squeezing in Bose-Einstein Condensates and related effects ";" Atomic clocks are the most precise clocks we have today. Their primary source to imprecision is the uncertainty inherent in quantum mechanics, i.e. quantum noise. This uncertainty can be diminished by squeezing the spin of the particles forming the clock, such that entangled states of the atoms are formed. Generating these sates is a challenge but it has been shown it is possible to form such spin squeezed states using a Bose-Einstein condensate. In this talk the theory behind this will be presented, and various related effects will be mentioned. In the end I will outline the work I am doing in my master thesis towards a different method of generating spin squeezing using Bose-Einstein condensates. "
"Niels Bohr Archive History of Science Seminar";"Niels Bohr Archive";"2010-03-04";"14.15";"";"";"Aud. A, Niels Bohr Institute,  Blegdamsvej 17";"Christopher Prom, Centre for Archive and Information Studies, University of Dundee ";"Christopher Prom Centre for Archive and Information Studies, University of Dundee Preserving the 'Papers' of 21st Century Science http://www.nba.nbi.dk/files/sem/04mar10.html "
"Talk by Piet Brouwer, Berlin";"Karsten Flensberg";"2010-03-04";"14:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø. D bygningen lokale 317 ";"Superconductor proximity effect in half metals ";""
"Master thesis defense by Pawel Klimek";"Stefania Xella";"2010-03-10";"Kl. 13:00";"";"";"Aud. A, Blegdamsvej";"Study of Z boson production using tau leptons final state in ATLAS ";" Study of Z boson production using tau leptons final state in ATLAS Abstract: The start-up of the Large Hadron Collider (LHC) has began a new exciting period in particle physics. One of its independent particle detectors is ATLAS which is designed as a general purpose detector. The goal of this project is to determine whether a pure sample of Z → τ+τ − events can be observed in ATLAS in the data collected during the first 100 pb−1 of collisions at 10 TeV. The final state considered is Z → τ+τ− → lepton νν hadron ν. All important backgrounds, including the severe QCD dijet production background, are considered. Several trigger and offline analysis strategies are presented, and an optimal choice is proposed, allowing a clear signal within the accumulated luminosity considered. The suggested selection allows to obtain a clear observation of Z → τ+τ− production, and therefore provides a data sample where the tau energy scale for hadronic tau lepton decays can be determined accurately in real data. The presentation will consist of three main parts. In the first part the introduction to the Standard Model will be presented. The second part will present an overview of the ATLAS detector and its elements most relevant for the present studies. The final part will be an explanation of the analysis employed in the study. "
"On the transport properties of heterostructured nanowires";"Jesper Nygård";"2010-03-11";"13:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D203";"Talk by Silvano de Franceschi, CEA Grenoble ";"Talk by Silvano de Franceschi, CEA Grenoble "
"Theoretical Particle Physics and Cosmology Seminar";"Konstantinos Zoubos";"2010-03-11";"14:00";"";"";"Aud A, Blegdamsvej 17, 2100 Copenhagen";"Scalar mode dynamics in Horava-Lifshitz gravity, Thomas Sotiriou, Cambridge University ";" Thomas Sotiriou (Cambridge U.) Title: Scalar mode dynamics in Horava-Lifshitz gravity Abstract: Horava-Lifshitz gravity has been proposed with the hope of being a UV complete gravity theory. After giving a brief overview of the various versions of the theory, I will focus on the dynamics of the extra scalar degree of freedom with respect to general relativity. The consistency and viability of each version depends crucially on the behaviour of this scalar mode. "
"Quantum Transport through self-assembled SiGe quantum dots";"Jesper Nygård";"2010-03-11";"15:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D203";"Talk by Georgios Katsaros, CEA Grenoble ";"The epitaxial growth of germanium on silicon leads to the self-assembly of SiGe nanocrystals via a process that allows the size, composition and position of the nanocrystals to be controlled. This level of control, combined with an inherent compatibility with silicon technology, could prove useful in nanoelectronic applications. Here we report the confinement of holes in quantum-dot devices made by directly contacting individual SiGe nanocrystals with aluminium electrodes, and the production of hybrid superconductor-semiconductor devices, such as resonant supercurrent transistors, when the dot is strongly coupled to the electrodes. Charge transport measurements on weakly coupled quantum dots reveal discrete energy spectra, with the confined hole states displaying anisotropic gyromagnetic factors and strong spin-orbit coupling strength with pronounced gate-voltage and magnetic-field dependence. Talk by Georgios Katsaros, CEA Grenoble "
"Cavity Optomechanics Towards Quantum Regime";"Eugene Polzik";"2010-03-12";"11:00";"";"";"Aud. M";"Mid-term colloquium Tolga Bagci ";" In this talk, I will try to give a general view of the field, Cavity Optomechanics , which deals with the interaction of mechanical resonators with light, confined in high-finesse cavities. Combined with state-of-the-art techniques , the field is promisingly approaching a regime where quantum radiation pressure effects might be dominant . The talk will also cover a relevant topic,namely radiation pressure cooling, that might herald the experimental demonstration of reaching the ground state of a nanomechanical resonator. Finally, I will relate the topic to our experiment where we propose using a two-color scheme for both probing and cooling of the mechanical object. "
"Theoretical High Energy Seminar";"N. E. Bjerrum-Bohr";"2010-03-16";"14:15";"";"";"Aud. A, Blegdamsvej 17, 2100";"Michael Volkov (LMTP, U. de Tours) Title: Superconducting electroweak vortices ";"Michael Volkov (LMTP, U. de Tours) Title: Superconducting electroweak vortices "
"Talk by Carlos A. Balseiro";"Andres Alejandro Reynoso";"2010-03-18";"11:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D203";"Electronic Transport Though Magnetic Molecules ";"Talk by Carlos A. Balseiro The ability to make molecular junctions, with molecules connecting two conducting leads, creates the opportunity to study how electric current flows though molecules. Using simple models and numerical renormalization group (NRG) calculations, we have studied different processes governing the electron flow through Spin-1/2 and Spin-1 molecular junctions. First we analyze the effect of soft phonon modes in Spin-1/2 molecules and show that, while the spin fluctuations are dominated by the bare couplings, the valence instabilities are determined by the dressed energies. This effect, related to the Franck-Condon effect, leads to anomalous transport properties that explain recent experimental observations in a family of organometalic molecules. We have also studied the transport though higher spin molecules. In recent experiments with Spin-1 molecules, it has been shown that the molecular spin and the magnetic anisotropy can be manipulated in a controllable way by mechanical motion. Using simple arguments and NRG results we interpret these new experiments and show that by mechanically stretching the molecule, spin anisotropy is induced changing the conductance of the molecular junction in a drastic way. "
"Alice Seminar";"Thomas Døssing";"2010-03-23";"13:15";"2010-03-23";"";"NBI, Blegdamsvej 21, lounge i Q-bygning";"Hydrodynamic modeling of ultrarelativistic heavy-ion collisions from FAIR to LHC, Igor Mishustin (FIAS Frankfurt) ";"""Hydrodynamic modeling of ultrarelativistic heavy-ion collisions from FAIR to LHC"" by Igor Mishustin (FIAS Frankfurt) "
"Discovery seminar";"Thomas Døssing";"2010-03-24";"14:15";"";"";"Auditorium A, Blegdamsvej 17, 2100 København Ø.";"Nuclear fragmentation reactions in basic research and medical applications, Igor Mishustin (FIAS Frankfurt) ";"""Nuclear fragmentation reactions in basic research and medical applications"" by Igor Mishustin (FIAS Frankfurt) "
"Talk by Wolfgang Tittel, University of Calgary ";"E. Polzik";"2010-04-01";"13:00";"";"";"Aud A";"Integrated quantum memory for quantum communication ";" Quantum memory constitutes a key element for quantum repeaters, which promise overcoming the distance barrier of quantum communication. Impressive experimental and theoretical progress has been reported over the past few years and gives hope that a workable quantum memory can eventually be built. We will present our latest results of storage of light in a Ti:Tm:LiNbO_3 waveguide cooled to 3 Kelvin using a photon echo quantum memory protocol. In particular, we will preset storage of sub ns pulses, simultaneous storage of more than hundred modes, and discuss progress towards storage of entangled photons. "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-04-06";"14:15";"";"";"Aud. A, Blegdamsvej 17";"Larisa Laperashvili (ITEP) E6 Unification and Cosmology ";"Larisa Laperashvili (ITEP) Title: E6 Unification and Cosmology "
"Niels Bohr Archive History of Science Seminar";"Niels Bohr Archive";"2010-04-08";"14:15";"";"";"Aud. A, Niels Bohr Institute, Blegdamsvej 17";"Graham Farmelo: Paul Dirac and the religion of mathematical beauty ";"Graham Farmelo: Paul Dirac and the religion of mathematical beauty Paul Dirac was the greatest English theoretical physicist since Newton. Dirac is famous for co-discovering quantum mechanics, for his beautiful equation for the behaviour of the electron and for predicting the existence of antimatter. Although sceptical of philosophy and religion, in later life Dirac became an apostle for the great importance of mathematical beauty in fundamental physics. It was 'like a religion' for him. In this talk, the basis of this belief, together with its successes and failures will be examined. "
"Informal Theoretical Seminar";"C. J. Pethick";"2010-04-13";"11.15";"2010-04-13";"12.30";"Bk2, Blegdamsvej 15";"""Quantum Hall Hierarchies from Conformal Field Theory"", Hans Hansson (Stockholm U.) ";" ""Quantum Hall Hierarchies from Conformal Field Theory"" Hans Hansson (Stockholm U.) We have developed conformal field theory techniques to construct explicit representative wave functions for the full hierarchy of spin-polarized Abelian quantum Hall states, as well asseveral familes of non-Abelian states. In this talk I will explain the physical motivation behind our construction and present typical examples. "
"Theoretical High Energy Seminar";"Marta Orselli";"2010-04-13";"14:15";"";"";"Aud. A, Blegdamsvej 17, 2100 Copenhagen";"Hawking Radiation, Information Paradox and Emission from the D1-D5 System, Borun Chowdhury (University of Amsterdam) ";" Borun Chowdhury (University of Amsterdam) Title: Hawking Radiation, Information Paradox and Emission from the D1-D5 System Abstract: I will present an introduction to the Penrose process, superradiance and Hawking radiation. I will then explain the information paradox and how robust it is. The fuzzball proposal will then be introduced with the two-charge systems being reviewed. A discussion of emission calculations for D1-D5-P black holes and for certain non-extremal fuzzballs from both the gravity and CFT perspectives will be presented. I will show how seemingly different emission processes in gravity, namely, Hawking radiation and superradiance from D1-D5-P black holes, and ergoregion instability of certain non-extremal fuzzballs, are only different manifestations of the same phenomenon in the CFT. "
"Dobbelt Midtvejskollokvium";"Aksel Walløe Hansen";"2010-04-22";"Hrs. 13:15";"";"";"Juliane Maries Vej 30, lokale 86";"Eva Podgrajsed and Emilie Hermansson ";"Eva Podgrajsed and Emilie Hermansson Foehn winds and katabatic winds are topographically dependent phenomena that frequentlly occur in Greenland. When air is cooled on the Greenland ice sheet it will descent down the slope towards the coast line due to gravitational force and thus a katabatic wind is formed. The other topographic wind pushes air up along a mountain and when the air is foreced to descend on the lees side it will get dry and warm compared to the windward side and thus the foehn event is not affected by negative bouyancy. When a pressure system enhances the katabatic flow in Greenland the event is called a Piteraq. The most extrem Piteraq ever to be documented in Greenland occured in Tasiilaq in February 1970, when wind gust up to 72 m/s were measured. The Piteraq event in Tasiilaq and a foehn event that happened on the south west tip of Greenland end of January 2010 are being studied in these two projects. The aim is to compare the DMI-HIRLAM K05 hydrostatic weather prediction system with the non-hydrostatic HARMONIE model in order to see which model best predicts these two topographic events. For the Piteraq event the wind speed is the most crucial parameter to predict compared to the temperature for the foehn event. In both the Piteraq and the foehn cases the two models captured the phenomena but the extreme values gott different results. The predicted wind speeds in the Piteraq got to low values from both models. HARMONIE predicted maximum wind speeds of 33m/s and HIRLAM of 26m/s compared to the observations that had maximum winds speeds of 54m/s. Also the temperatures in the foehn event got to low values from both models. HARMONIE predicted maximum temperature of 8oC and HIRLAM of 4oC compared to the maximum observed temperature of 13.2oC. Internal supervisor: Aksel Walløe Hansen, NBI Eksternal supervisors: Niels Woetmann Nielsen, DMI and Leif Rasmussen, DMI "
"Specialeforsvar af Jessica Y. Zhou";"John Hertz";"2010-05-03";"10:00";"";"";"Aud. A";"Computational modelling of neural networks in the spinal cord ";"In this thesis, a theoretical, computer-simulated model of neural networks in the spinal cord is studied. The network described in the model is inhomogeneous, with random connectivity and single-neuron parameters distributed around their central values. Both excitatory and inhibitory neurons are contained in the network, which also receives input neurons from external environments. All these neurons are connected to each other via synapses, modelled as synaptic conductances. To make the model more biologically realistic, the neurons are divided into two compartments - soma and dendrite. The neurons fire during network activity. We measure population firing rates and membrane potentials of single neurons selected randomly. Because the neuronal parameters in the inhomogeneous network can be spread to large or small extents by a so-called ``spread factor"" - denoting varying degrees of inhomogeneity, firings are investigated for different values of the spread factor, and the value for which the firing pattern is most like experimental observations is determined. We also explore the cases where the sodium and potassium conductances are knocked out in some neurons. The results are compared with corresponding cases in the so-called BRK model for a single neuron. Furthermore, correlations and power spectra of firing rates and membrane potentials are computed. Finally, the mechanism responsible for the generation of irregular spiking in the 20-Hz frequency range is analysed."" "
"Quantum Plasmonics";"E. Polzik";"2010-05-04";"10:15";"";"";"Aud. A";"Talk by Ulrik Lund Andersen, DTU ";" Talk by Ulrik Lund Andersen, DTU The emergent field of quantum plasmonics has received enormous interest due to its unique promises for the way light can be localized beyond the diffraction limit and manipulated at the nanoscale. One particular interesting application of quantum technologies based on surface plasmons is quantum information as it allows for scalability and coherent coupling to single emitters. In this talk I will discuss recent advances in the excitation and propagation of non-classical surface plasmons. In particular, I will address a recent experiment on the faithful transmission of squeezed states of light through plasmonic waveguides, and report on the recent progress on the excitation of single surface plasmons with Nitrogen-Vacancy centers in diamond "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-05-04";"14:00";"";"";"Auditorium A, Blegdamsvej 17";"Classical analog of quantum Schwarzschild black hole and the mystery of log(3), Viktor Berezin (INR, Moscow) ";"Viktor Berezin (INR, Moscow) Title: Classical analog of quantum Schwarzschild black hole and the mystery of log(3) "
"Special Colloquium";"Mogens Høgh Jensen";"2010-05-04";"15.15";"";"";"Aud A";"Physical Review Letters, Talk by Ling Miao ";" Physical Review Letters: Its Review Process and Publications, Its Role in Physics Research, and Its Future. For researchers working in physical sciences, Physical Review Letters is one of the most desirable venues for publication of their work. What makes the journal highly desirable? And, how should it meet the challenges posed by an increasingly competitive and more ""impact""-oriented scientific publishing culture? In this talk, I will discuss these questions with you by looking at PRL's publication philosophy, its review process and publications, and what it means to the physics community and to physics research. Your thoughts and views as well as suggestions will be most welcome. "
"Talk by Martin Mourigal, ILL and EPFL";"Kim Lefmann";"2010-05-05";"10:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, Aud. 7";"Non-Linear Spin Dynamics on the Square-lattice &#8211; Neutron Scattering and Theory ";" The S = ½ square-lattice Heisenberg antiferromagnet (SLHAF) describes a large variety of Mott insulating materials and has received tremendous attention in the last decades. Spin-Wave Theory (SWT) is a successful paradigm to describe its spin dynamics although the existence of T=0 quantum fluctuations may lead to failures of the spin-wave picture and emergence of new phenomena. Recent experimental efforts focused on the deviations from the linear spin-wave behavior, in zero and finite applied magnetic field, in particular at the magnetic zone boundary points (π,0) and (π/2,π/2). After a general introduction to the dynamics of low-dimensional quantum magnets and their study by neutron scattering, we will discuss the case of the SLHAF from both the experimental and the theoretical standpoints. In particular, we will present recent inelastic neutron scattering results, in zero and finite field, on the model compounds CFTD [Cu(DCOO)2.4D2O] and CAPCC [(2-amino-5-chloropyridinium)CuCl4] confirming the role of quantum effects already in non-frustrated materials. We will report the observation of multi-magnon continua as well as of spontaneous magnon decays as two signatures of non-linear quantum effects. Our findings will be compared with theoretical and numerical results obtained with SWT, Quantum Monte-Carlo and Exact Diagonalization. Talk by: Martin Mourigal, Institut Laue-Langevin (ILL), Grenoble, France & Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland "
"PhD defence by Christodoulos Chatzichristodoulou";"Kim Lefmann";"2010-05-05";"14:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø Auditorium 6";"";"PhD defence by Christodoulos Chatzichristodoulou "
"The quantum phase transitions of metals";"Jens Paaske";"2010-05-06";"11:00";"";"";"NBI, H.C. Ørsted Institutet, Universitetsparken 5, 2100 København Ø. Lokale D203";"Talk by Subir Sachdev ";"Almost all correlated electron metals exhibit instabilities to ordered phases with broken spin or lattice symmetries: prominent examples are found in the cuprates, the pnictides, and in many rare-earth intermetallics. Such phase transitions were classified and studied in a classic paper by Hertz in 1976. I will argue that while the Hertz approach is largely correct in spatial dimension d=3, new strong-coupled field theories are required in the experimentally important case of d=2. I will describe recent progress towards solution of these strong coupling problems. Talk by Subir Sachdev "
"Talk by Alexander Lvovsky";"Eugene Polzik";"2010-05-06";"11:15";"";"";"Aud. A";"The ""black box"" problem for quantum light, Alexander Lvovsky, Universtity of Calgary ";" The famous ""black box"" problem, emerging in many fields of science and engineering, is also significant in the context of quantum information processing. This is because assembling a quantum information processing circuit requires precise knowledge of the properties of its each component, i.e. the ability to predict the effect of the component on an arbitrary input quantum state. This knowledge is acquired through quantum process tomography - a procedure in which certain ""probe"" states are sent into the quantum ""black box"", and the corresponding outputs are measured. Surprisingly, black boxes that process quantum optical information can be completely characterized using coherent states, i.e. simple laser pulses, as the probe states. We shall discuss the theory and implementation of this procedure as well as a few examples of its practical application. "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-05-06";"14:15";"";"";"Auditorium A, Blegdamsvej 17";" QCD at finite chemical potential: Complex Langevin dynamics and the sign problem, Gert Aarts (Swansea University) ";" Gert Aarts (Swansea University) Title: QCD at finite chemical potential: complex Langevin dynamics and the sign problem "
"NBIA Colloquium";"P. H. Damgaard";"2010-05-07";"2:15 pm";"";"";"Aud. A";"Gamma-Ray Bursts: Cosmic nano-physics at work, Mikhail Medvedev, NBIA and Kansas University ";" Title: ""Gamma-Ray Bursts: Cosmic nano-physics at work"" Abstract: Shall humans have gamma-ray-sensitive eyes, they would see nothing except short bright flashed in the sky at a rate of about one per day. These are the so-called Gamma-Ray Bursts, or GRBs, whose origin is still debated. We know now, however, that these are, by far, the brightest events in the Universe: energetically, they outshine the entire Universe but only for their duration of a few tens of seconds. Typical GRBs are very far from us; they shine on the other side of the Universe, so we cannot directly image them. Yet, the situation isn't hopeless. In this talk I will describe what we have learned about GRBs and, especially, how they emit the observed radiation -- a very intriguing question with a rather counter-intuitive answer. "
"Theoretical High Energy Seminar";"E Bjerrum-Bohr";"2010-05-11";"14.15";"";"";"Aud A, Blegdamsvej";"Conformal or Walking? Monte Carlo Renormalization Group studies of technicolor-inspired models, Anna Hasenfratz (Univ. Colorado, Boulder) ";" Anna Hasenfratz (Univ. Colorado, Boulder) Title: Conformal or Walking? Monte Carlo Renormalization Group studies of technicolor-inspired models Abstract: Models with many fermions or fermions in higher representations can be candidates for extended technicolor or unparticle theories. The phenomenologically most interesting models show ""walking"" or develop an infrared fixed point in strong gauge coupling. Lattice methods can be used to explore the phase diagram of these models, and Monte Carlo renormalization group (MCRG) methods are especially effective in identifying an infrared fixed point and measuring anomalous dimensions (critical indexes). In this talk I discuss the MCRG method as applied to SU(3) gauge models with many fermion flavors and discuss some new results in the 8, 12 and 16 flavor models. "
"Collective mesoscopic spin control";"Eugene Polzik";"2010-05-12";"11:15";"";"";"Aud. A";"Talk by Prof. Ivan Deutsch University of New Mexico ";"Control of complex quantum systems has applications in many-body physics, quantum information processing, and high-precision metrology. Mesoscopic ensembles of cold atomic spins are an ideal testbed for such explorations, given the growing quantum-control toolbox. In a cigar-shaped trap, when the ensemble is optically thick on resonance, the spins coherently couple to the polarization state of a paraxial laser probe. The photons serve as a “quantum bus” that transfers quantum correlations between atoms and entangles them. Spin-squeezed states based on this mechanism have recently been produced, representing an important step toward more complex control. In this seminar I will discuss new approaches to achieving more sophisticated and general control, including unitary evolution through coherent optical feedback and quantum erasure, exponential squeezing via phase matching, and the production of Schroedinger kittens via heralded scattering of single photons. "
"Lecture by Brenda Dingus ";"DARK";"2010-05-12";"13:00";"";"14:30";"Meetingroom A, 2. fl. Rockefeller";"Gamma-Ray Emission from the Milky Way Probing the Origin of Cosmic Rays ";" Brenda Dingus, cospokesperson of the High Altitude Water Cherenkov (HAWC) observatory. You can learn more about the project at www.hawc-observatory.org HAWC is beginning construction soon and will make detailed observations of 100 GeV-100TeV cosmic rays and gamma rays. Gamma-Ray Emission from the Milky Way Probing the Origin of Cosmic Rays Cosmic rays were discovered nearly 100 years ago. These primarily hadronic particles have been measured in the near Earth environment, but we have not been able to determine their origin primarily because magnetic fields deflect the cosmic rays in random directions. However, gamma rays are produced by cosmic rays interacting near their sources and as they propagate through the Galaxy. The plane of the Milky Way is a bright diffuse source of GeV-TeV gamma rays. The Milagro Gamma-Ray Observatory The Milagro observatory has measured this diffuse gamma ray flux which is much larger than expected given the local cosmic ray measurements. Deeper observations with current and future observatories will remove more of the unresolved localized source contributions and allow spectral measurements of the diffuse gamma-ray emission. Different spectra as well as a different spatial morphology are expected for different contributions to the gamma-ray flux. For example, the higher the energy of the gamma rays the more likely the gamma rays are produced by hadrons. The High Altitude Water Cherenkov (HAWC) observatory, a next generation version of Milagro, will have the sensitivity to observe these highest energy gamma rays and shed light on the origin of cosmic rays. "
"Seminar with Eiichiro Komatsu";"Steen Hansen";"2010-05-20";"14:15";"";"";"Aud. A, Blegdamsvej";"""WMAP 7-year Results: Cosmological Interpretation"" ";"Eiichiro Komatsu will give a seminar with the title ""WMAP 7-year Results: Cosmological Interpretation"" Tomorrow, thursday May 20th, at 14.15 Aud A, Blegdamsvej. "
"NBIA Colloquium";"P.H. Damgaard";"2010-05-21";"2:15 pm";"";"";"Aud. A, Blv.";"""Opening the Gravitational Wave Window to the Universe"", Prof. B. Schutz, MPI Potsdam ";" Speaker: Professor Bernard Schutz, Max Planck Institute, Potsdam Title: Opening the Gravitational Wave Window to the Universe Abstract: The large gravitational wave detectors like LIGO and VIRGO are increasing their range and sensitivity step-by-step, so that we can be confident that, sometime between 2014 and 2016, they will begin making regular observations of neutron stars and black holes colliding and merging together in the near universe. Early in the next decade the much more sensitive space detector LISA may begin to survey the entire universe for black hole mergers. And sometime during this period, radio astronomers could begin to measure the tiny effects of gravitational waves on the signals they get from pulsars. This talk will focus on what we expect to learn from gravitational wave astronomy with these instruments about stars, galaxies, the universe as a whole, and about gravity itself. And it will look at possible future developments: large detectors in Asian, super-sensitive underground detectors in the US and Europe. "
"Midtvejskollokvium: Mads Højsgaard";"Maorten Bo Madsen";"2010-05-25";"13:15";"";"";"NBI, Rockefeller,Juliane Maries Vej 30, lokale 071";"Phoenix Mars Lander ";" Phoenix Mars Lander Vejleder: Morten Bo Madsen Resume: Phoenix Mars Lander blev sendt til mars i august 2007 og landede den 25. maj 2008, hvor den arbejdede i 151 mars-dage (sols) pÃ¥ Mars-overfladen med at indsamle data af forskellig karakter. HovedformÃ¥let med Phoenix missionen var at undersøge overfladen af de arktiske egne pÃ¥ Mars, som tidligere missioner havde vist, med stor sandsynlighed indeholder vand-is. Udover at detektere og undersøge vand-isen under overfladen pÃ¥ Mars, udførte Phoenix mÃ¥linger af bl.a atmosfæren og jordbunden og tog billeder af landskabet og sig selv, med mange forskellige filtre. Dette midtvejskollokvium vil omhandle Phoenix landeren samt den mission den udførte, med speciel vægt pÃ¥ surface stereo imageren og de sÃ¥kaldte kalibreringstargets, der blev brugt til at lave spektrale mÃ¥linger af jorden og støvet pÃ¥ mars. Image composite "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-05-25";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"Koenraad Schalm (Leiden University): Building a holographic Fermi Liquid ";" Koenraad Schalm (Leiden University) Title: Building a holographic Fermi Liquid "
"NBA History of Science Seminar";"Niels Bohr Archive";"2010-05-26";"14.15";"";"";"Aud. A, Niels Bohr Institute, Blegdamsvej 17";" The Strange Friendship of Pauli and Jung. When Physics Met Psychology, Arthur I. Miller ";" Arthur I. Miller University College London The Strange Friendship of Pauli and Jung When Physics Met Psychology See webpage "
"Speciale Kollokvium";"N. Obers";"2010-05-26";"14:00";"";"";"Bk2 (NBIA)";"The fluid/gravity correspondence ";" Andreas Vigand Pedersen Abstract: The AdS/CFT correspondence provides us with a remarkable tool for studying strongly coupled field theories. In essence, the AdS/CFT correspondence is a conjectured mathematical equivalence between certain gravitational theories and non-gravitational quantum gauge theories. More specifically, the AdS/CFT correspondence predicts a duality between a set of gravitational theories, defined on Anti-de Sitter space (AdS), and a set of conformal field theories (CFT), defined on the boundary of the corresponding anti-de Sitter space. It is believed that any quantum field theory admits an effective description in terms of fluid dynamics at sufficiently high temperatures and energy densities. Applying this principle to the AdS/CFT correspondence, we obtain an equivalence between gravity and fluid dynamics (of conformal field theories), known as the fluid/gravity correspondence. Recently, a new approach to the fluid/gravity correspondence has emerged. This approach directly utilizes the well-understood gravitational equations on the gravity side to gain new information about the fluid dynamical behavior on the gauge theory side. It has been the purpose of my thesis to examine this new aspect of the AdS/CFT correspondence. In this talk I will give a short introduction to the AdS/CFT correspondence and conformal fluid dynamics. I will then move on to explaining how, by solving the gravitational equations perturbatively around certain D dimensional brane solutions, the equations of gravity are dual to those of conformal fluid dynamics. Moreover, I show how the fluid/gravity correspondence can be used to extract new information about the dual fluid - information otherwise completely unavailable using quantum field theoretical perturbative methods. The results can be seen both as a verification of the correctness of the fluid/gravity correspondence and as an extremely powerful laboratory for examining the fluid dynamic properties of strongly coupled theories. Finally I will introduce a relatively new class of exact (black hole) solutions to Einstein's equations, on anti-de Sitter backgrounds, and explain how these objects fit beautifully into the fluid/gravity correspondence. Supervisor: N. Obers "
"Theoretical High Energy Seminar";"Marta Orselli";"2010-05-27";"11:00";"";"";"FB6, Blegdamsvej 17";"Fluxes, Geometries and Non-Geometries, Savdeep Sethi (University of Chicago) ";" Savdeep Sethi (University of Chicago) Title: ""Fluxes, Geometries and Non-Geometries"" "
"Quantum Transport in Low Dimensional Systems";"Jens Paaske and Karsten Flensberg";"2010-05-31";"";"2010-06-04";"";"HCØ, Universitetsparken 5, 2100 København Ø";"A one-week intensive course from May 31 - June 4 2010 with a number of invited speakers. ";" Niels Bohr Institute & Nano-Science Center offers a one-week intensive course from May 31 - June 4 2010 with a number of invited speakers teachers lecturing on selected topics at the forefront of condensed matter physics. The course is minded for PhD students working in the field of condensed matter physics, and with a special interest in low-dimensional systems including such topics as quantum dots and wires, graphene, topological phases, and spin-qubits. Invited Lecturers •Leonid Glazman (Yale University) •Ady Stern (Weizmann Institute of Science) •Charles Marcus (Harvard University) •Dominik Zumbühl (Universität Basel) Local Lecturers •Karsten Flensberg •Jens Paaske Apply for attendance To apply for attendance, send email to paaske@nbi.ku.dk with information of name, institution, title of PhD project, and supervisor. The maximum number of students will be limited to 20. All students will have to cover their own expenses. The PhD course is organized in collaboration with the regular graduate course ""Quantum transport"" delivered at the NBI in the period April 19 - June 25. Workload The course will have a total workload of 5 ECTS. Detailed programme and recommended reading See the entire programme including schedule here (pdf). "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-06-01";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"The QCD Nature of Dark Energy , Ariel Zhitnitsky (UBC, Vancoiuver) ";" Ariel Zhitnitsky (UBC, Vancouver) Title: The QCD Nature of Dark Energy "
"Master Thesis by Jon Saabye";"Niels Kristian Højerslev";"2010-06-01";"14:15";"";"";" lk. 86 Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København 2100, lokale 86";"Inter-Annual Sea Level Variations Forced by Wind Stress in the Subtropical North Atlantic ";"Inter-Annual Sea level Variations Forced by Wind Stress in the Subtropical North Arlantic (this talk will be in Danish) Abstract This master thesis is the result of an investigation in how wind stress influence the variability of the Sea Surface Height (SSH) in the north Atlantic, in the period 1993-2008. A Reduced Gravity Model (RGM) has been used to compare the variability of the pycnocline to the SSH measured by the satellites TOPEX/Poseidon and Jason-1. The RGM is a two layer model, with a motionless lower layer, also referred to as an 1½-layer model. The model neglects thermodynamics and bathymetry effects, but includes real coast lines. The RGM is discretized on an Arakawa C-grid and solved with a standard leap-frog scheme. Empirical Orthogonal Functions (EOFs) have been used to decompose the satellite altimetry, RGM output, and the curl of the wind stress into statistically independent spatial and temporal patterns. After using a box-car filter, the first EOF from the satellite altimetry decribes 50.3% of the variability, with a dominating signal in the Gulf Stream system and in the tropics. The principal component shows a decrease from 1994-2004. This was found to be related to the first baroclinic mode and the adjustment time of the Rossby waves in the RGM. The second EOF describes 17.1% of the variability, with a dominating signal in the Sargasso Sea. The principal component had a period of 3-5 years, which was in good agreement with the wind stress curl Supervisors: Niels Kristian Højerslev, NBI, University of Copenhagen Torben Schmith and Ole Krarup Leth, Danish Meteorological Institute "
"Simuleret udglødning";"Bjarne Andresen";"2010-06-03";"10:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, lokale D317";"Midtvejskollokvium af Peter Andersen ";"Emnet er simuleret udglødning brugt pÃ¥ problemstillingen: ""At lægge et optimalt skema for et gymnasium"", med alt hvad det indebærer af bindinger og prioriteter i forbindelse med lokaler, fag, lærere, mellemtimer, forskellige fags præferencer til fordelingen af timerne henover ugen, osv. Midtvejskollokvium af Peter Andersen "
"Karakterisering af superledende tapes med MgB2 ved hjælp af høj energi røngten";"Per Hedegård";"2010-06-03";"13:30";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, lokale D105";"Specialeforsvar af Pasmus Pinholt ";"MÃ¥let med projektet var at vurdere om høj energi røngten diffraktion kan være et brugbart redskab til at vurdere superledende trÃ¥de lavet med MgB2. Superledende trÃ¥de med MgB2 blev produceret og karakteriseret. TrÃ¥dene blev varieret med hensyn til urenheder, komposition og kornstørrelsen. Karakteriseringen blev gjort ved hjælp af magnetisk modstand mÃ¥ling, hvor den kritiske strøm blev bestemt ved forskellige temperaturer og magnetfelter, samt bestemmelse af den kritiske temperatur ved hjælp af et ac-suseptometer. Derudover blev trÃ¥dene udsat for varmebehandling og samtidig blev fasedannelsen bestemt ""in situ"", ved hjælp af høj energi XRD. Følgende blev blandt andet undersøgt: - Uændret kornstørrelse af MgB2 under opvarmning - Tilvæksten af Fe2B - Dannelse af MgB2 ved temperaturer lavere end smeltepunkt af Mg "
"Talk by Xian-Min Jin";"Eugene Polzik";"2010-06-05";"10:15";"";"";"Aud. A";"Experimental Free-Space Quantum Teleportation & Quantum Memory of SPDC Entanglement, University of Science and Technology of China ";" An optical free-space link is highly desirable for extending the transfer distance of quantum teleportation, because of its low atmospheric absorption for certain ranges of wavelength. Here we achieve free-space implementation of quantum teleportation over 16 km. An active feed-forward technique has been developed to enable real-time information transfer. An average fidelity of 89%, well beyond the classical limit of 2/3, is achieved. Our result confirms the feasibility of space-based experimentsEmploying photonic entangled pairs to implement linear optical quantum computing holds the promise to realize scalable quantum information processing (QIP). In last decade, intensive researches have been carried out with spontaneous parametric down-converted (SPDC) entanglement sources and remarkable progress has been achieved. However, scalable linear optical computing is still extremely challenging, due to the lack of a quantum memory for the SPDC photons. We report the first experimental preparation of a 5 MHz frequency-uncorrelated SPDC source and reversibly mapping the generated entangled photons into and out of a remote atomic quantum memory. Our work establishes a crucial element to implement scalable linear optical quantum computing and opens up a realistic avenue towards all-optical QIP "
"Kollokvium af Erik Melchior Pedersen ";"Holger Bech Nielsen";"2010-06-07";"14:00";"2010-06-07";"";"Aud. D";"EINSTEINS KOSMOLOGISKE BETRAGTNINGER UD FRA DEN ALMENE RELATIVITETSTEORI ";" EINSTEINS KOSMOLOGISKE BETRAGTNINGER UD FRA DEN ALMENE RELATIVITETSTEORI. Einsteins forsøg på at beskrive et rumligt endeligt univers ved indførelse af en universal konstant. Muligheden for et ""endeligt"" og ""ubegrænset"" univers ifølge Einstein. Det rumligt endelige univers med en uniform fordeling af stof. Det ekstra led i feltligningerne for gravitationen KONSTANTEN ET PARADOKS : ""IKKE-SERIØS"" FEJLTAGELSE ELLER I VIRKELIGHEDEN EN GENIALITET I DEN MODERNE KOSMOLOGI? Vejleder: Holger Bech Nielsen "
"Theoretical High Energy Seminar";"E. Bjerrum-Bohr";"2010-06-10";"14.15";"2010-06-10";"15.15";"Aud A, Blegdamsvej";"Perturbative Quantum Gravity from Gauge Theory , Henrik Johansson, Sacley ";" Henrik Johansson, Sacley Perturbative Quantum Gravity from Gauge Theory "
"Master Thesis by Eva Podgrajsek";"Aksel Walløe Hansen";"2010-06-10";"14:15";"";"";" lk. 86,  Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København 2100, lokale 86";"A test of two NWP models on a Foehn event ";" A test of two NWP models on a Foehn event The defense will be in Swedish Sammanfattning Föhn händelser är fenomen som sker överallt i världen och ändrar vädret drastiskt. Under endast ett par timmar kan temperaturen stiga med flera grader och fuktigheten sjunka extremt. Detta kan fÃ¥ bÃ¥de miljömässiga och ekonomiska konsekvenser och det är därför viktigt att ha NWP modeller som kan förutspÃ¥ föhn händelser. Idag använder Danmarks Meteorologiska Institut hydrostatiska modeller för att göra sina prognoser. Syftet med detta projekt är att testa en ny icke-hydrostatisk HARMONIE modell som har en upplösning pÃ¥ 2,5km och se om den är bättre pÃ¥ att förutspÃ¥ föhn hädelser jämfört med den operativa K05 HIRLAM modellen med upplösning pÃ¥ 5 km. Även mer kunskap om föhn vindar vill fÃ¥s. En föhn händelse som skedde pÃ¥ sydvästra Grönland den 30-31 januari 2010 studeras i rapporten. Undersökningarna som har gjorts för detta projekt har gett resultatet att bÃ¥da modellerna fÃ¥r prognoser som visar att det kommer att bli en föhn hädelse i tidsperioden som studeras. Men det är stor skillnad i hur bra modellerna förutspÃ¥r temperatur, relativ fuktighet och vindhastighet. I temperaturprognoserna fick HIRLAM modellen ett minimum fel pÃ¥ -7°C och HARMONIE modellen fick ett minimum fel pÃ¥ -4°C jämfört med den maximala temperaturen som observerades under föhn händelsen. HARMONIE modellen har vindhastighetsprognoser som följer de observerade värdenas ökningar och sjunkningar mycket bättre än HIRLAM modellen, som mestadels har för lÃ¥ga vindhastigheter. Men det är i de relativa fuktighetsprognoserna som skillnaden mellan de tvÃ¥ modellerna är som störst. HIRLAM modellen fick minimum fel pÃ¥ 33 % medan HARMONIE modellen fick ett minimum fel pÃ¥ 5,1% jämfört med det minsta observerade värdet. Huvudresultatet i projektet är att luften i den specifika föhn händelsen sjunker pÃ¥ grund av lee vÃ¥gor, dvs. en topografisk betingad atmosfärisk stÃ¥ende vÃ¥g och att den icke-hydrostatiska HARMONIE modellen är bättre pÃ¥ att förutspÃ¥ temperatur, relativ fuktighet och vindhastighet jämfört med den hydrostatiska HIRLAM K05 modellen. Den markanta skillnaden mellan modellerna ligger in den relativa fuktighetsprognosen. För att fÃ¥ ett mer pÃ¥litligt resultat mÃ¥ste modellerna köras med samma upplösning och fler föhn händelser mÃ¥ste studeras. Vejledere: Aksel Walløe Hansen, NBI, Niels Woermann Nilesen, DMI Abstract Foehn events are phenomena that happen all around the world and change the weather drastically. In a few hours the temperature can rise several degrees and the humidity can fall extremely. This can have both environmental and economic effects and thus it is important to have good NWP models that can predict foehn events. At the present Denmark's Meteorological Institute uses hydrostatic models in their weather forecasts. The aim of this project is to test if a new non-hydrostatic HARMONIE model with a resolution of 2.5km is better than the operational K05 HIRLAM model with a resolution of 5km in predicting a foehn event and to get more knowledge about foehn events. A foehn case that happened in southwest Greenland on the 30-31st of January 2010 is being studied. From the investigation done in this report the result is that both models do predict that there will be a foehn event in the period that is studied. But there is a big difference in how well the two models predict the three parameters: temperature, relative humidity and wind speed. For the temperature the HIRLAM model had a minimum error of approximate -7°C and HARMONIE had an error of approximate -4°C compared to the maximum observed temperature. The wind speed forecasts by HARMONIE where much better in predicting the rises and falls of the wind compared to the HIRLAM forecast, which predicted to small wind speed errors. The results from the relative humidity forecasts have the most signifcant differences when comparing the two models. The HIRLAM model got errors of 33% and HARMONIE got a minimum error of 5.1% compared to the minimum observed relative humidity. The main result is thus that this foehn event involves descent of air with lee waves and that the non-hydrostatic HARMONIE model is better in predicting temperature, relative humidity and wind speed compared to the hydrostatic DMI-HIRLAM K05 model for this foehn case. The signifcant difference between the models lies in the forecast of the relative humidity. More case studies and model runs with the same resolution are needed, to obtain a reliable conclusion of which of the two models that is best in forecasting a foehn event. Supervisors: Aksel Walløe Hansen, NBI, Niels Woetmann Nielsen, DMI "
"Master thesis by Frederik Treue";"Karsten Flensberg";"2010-06-10";"14:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, Aud. 5";"Spin-orbit coupling and chirality in carbon nanotubes ";"Master thesis by Frederik Treue "
"Specialeforsvar: Henning Gisselø";"Aksel Walløe Hansen";"2010-06-11";"13:15";"";"";"lk. 71, Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"Et studie af sigtbarhedsparameterisering og aerosolers 1. indirekte effekt i en numerisk vejrprognosemodel ";" Et studie af sigtbarhedsparameterisering og aerosolers 1. indirekte effekt i en numerisk vejrprognosemodel Abstrakt SkydrÃ¥bekoncentrationen (Nd) pÃ¥virker strÃ¥lingsegenskaberne i skyer/tÃ¥ge og dermed ogsÃ¥ sigtbarheden. Reduceret sigtbarhed (specielt tÃ¥ge med sigtbarhed under 1000 m) har store sikkerhedsmæssige og økonomiske konsekvenser for afviklingen af flytrafikken, men ogsÃ¥ skibs- og biltrafikken berøres. I den operationelle numeriske vejrprognosemodel HIRLAM (HIgh Resolution Limited Area Model) har selv smÃ¥ ændringer i temperatur og fugtighed betydning for sigtbarhedsberegningen. Dette har den konsekvens, at modellen i nogle tilfælde forudsiger en for hurtig tÃ¥gedannelse og sammes opløsning. En alternativ parameterisering af sigtbarheden er: VIS = (LWC • Nd)-0,65, hvor VIS er sigtbarheden og LWC (Liquid Water Content) er luftens indhold af flydende skyvand. I dette projekt er denne parameterisering testet i en 1-dimensional og 3-dimensional version af HIRLAM. Resultaterne er sammenlignet med den nuværende sigtbarhedsparameterisering i HIRLAM og med observationer fra en vejrsituation, hvor der forekom udstrÃ¥lingstÃ¥ge i Danmark. En forøget mængde aerosoler resulterer i flere og mindre skydrÃ¥ber. Aerosolers 1. indirekte effekt, som beskriver en forøget refleksion af kortbølget strÃ¥ling fra skyer med flere og mindre drÃ¥ber, er blevet implementeret i bÃ¥de den 1-dimensionale og 3-dimensionale version af HIRLAM. NÃ¥r Nd pertuberes har det en indvirkning pÃ¥ den beregnede sigtbarhed, LWC, skydække, overfladetemperatur og den mængde kortbølgede strÃ¥ling som jordoverfladen modtager. Det er dog ikke klart, om de beregnede værdier er forbedrede i forhold til observationer. Omkring den nye sigtbarhedsparameterisering kan det konkluderes, at kvaliteten ikke er god nok til implementering i 3-D sin nuværende form. Dette kan til dels skyldes, at den værdi af LWC der benyttes, bliver beregnet i nederste modelniveau, som ligger i ca. 30 meters højde over jordoverfladen og ikke i 2 meters højde, hvor sigtbarheden mÃ¥les. Vejledere: Aksel Walløe Hansen, NBI, Ulrik Korsholm, DMI og Niels Woetmann Nielsen, DMI "
"NBIA Colloquium";"P.H. Damgaard";"2010-06-11";"2:15 pm";"";"";"Aud. A, Blv.";"""Life as a major force in shaping the Earth"", Prof. M. Rosing, Copenhagen University ";" Speaker: Professor M. Rosing, Copenhagen University Title: Life as a major force in shaping the Earth Refreshments after the lecture! "
"Midtvejskollokvium: Sarah M. P. Berben";"Centre for Ice and Climate";"2010-06-14";"15:00";"";"";"Rockefeller, Juliane Maries Vej 30, room 235";"The effect of forced ventilation through snow on the stable water isotope content of the vapor and the snow - an experiment ";" Midtvejskollokvium: Sarah M. P. Berben Academic supervisors: Sigfus J. Johnsen and Hans Christian Steen-Larsen Abstract The stable water isotope signal throughout an ice core is a well known and often used proxy for past temperature reconstructions, and is important in our understanding of the climate system. The knowledge about the post-depositional processes influencing the isotope signal within the snowpack is therefore important. As wind blow across the snow surface, micro high and low pressure areas arise because of sastrugi. These pressure differences create forced ventilation through the snow pack, which then affects the interstitial mass exchange between water vapor and snow crystals, and therefore perhaps the climatic signal stored in the snow. In order of understanding the physics behind this ongoing exchange, a combination of modeling and a controlled experiment has been set up. The process of forced ventilation –as it is believed to occur on Greenland and Antarctica- has been simulated. The snow within this experiment is collected in Greenland during the 2009 field season of the new deep drilling project in North-West Greenland (NEEM). Within this experiment, dry air is pushed through a snow sample with fixed thickness. This sample has a known isotopic content and is kept at different sub-zero temperatures. The flow rate of the air has been controlled between 0.15 and 1.50 l/min. After the interaction between the water vapor and the ice crystals, the isotope signal is been studied. New in this research are the continuous measurements of the isotope content with a Picarro WS-CRDS analyzer of the water vapor. Eventually -to understand the effect of ventilation forced through snow on the stable isotope content of the water vapor- the results of the experiment are compared with the output from a Rayleigh type model. This research investigated the interstitial mass exchange between vapor and snow crystals and delivered thereby some consistently experimental data. Although the remaining non understood issues, it still can be seen as a contribution to the understanding of the effect of forced ventilation on the mean isotope signal in the snow, and its possible implications for the derived temperature signal from the water isotope ratio of an ice core. "
"Ultracold Atoms Group Meeting";"C. J. Pethick";"2010-06-15";"10.15";"";"";"Bk2, Blegdamsvej 15";"Mercury Clocks and Reports from meetings ";" Lin Yi is visiting from Paris Observatory, and will describe work towards making an optical clock based on mercury. An abstract may be found here . Following that Zhenhua Yu will report on the Nice meeting on quantum coherence and Sascha Zoellner will tell us about the DAMOP meeting. "
"PhD Defence by Jonatan Bohr Brask";"Anders S. Sørensen";"2010-06-23";"14.15";"";"";"Aud. M";"Long-distance distribution of discrete and continuous variable entanglement with atomic ensembles ";" Entanglement is one of the curious counter-intuitive features which sets quantum mechanics apart from classical physics. It lies at the foundations of quantum theory, and at the same it can be harnessed for applications such as quantum teleportation and secure communication schemes. This thesis is concerned with the study and theoretical development of methods for generating entangled states between objects at distant locations. Quantum states are fragile creatures which are easily degraded by interactions with a noisy environment. The most viable carrier of quantum states over long distances is light, because it moves fast and couples relatively weakly to its surroundings, but even light travelling e.g. in optical fibres is subject to losses which grow exponentially with distance. For classical communication this problem is solved by amplification, but for quantum signals the so-called no-cloning theorem, which stipulates that an unknown quantum state cannot be copied, implies that noiseless amplification is impossible. Instead, the problem can be solved by first generating entanglement over short distances and then ``swapping'' the entanglement to longer distances via quantum teleportation. Schemes which implement this approach are known as quantum repeaters. The thesis presents two new proposals for quantum repeater schemes. In my talk I will give an introduction to quantum repeaters and describe the ideas behind the new proposals. The defense will be followed by a reception. "
"Midtvejskollokvium by Leif Skovbo";"Eigil Kaas";"2010-06-24";"10:00";"";"";"lk. 71, Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"Weighting of an ensemble of climate models ";"Weighting of an ensemble of climate models Abstract: When people talk about climate change one question is always 'How warm will it be in the future?'. To answer this question we use climate models. General circulation models simulating the atmosphere and ocean, AOGCMs. One model predicts an outcome. The next a different outcome. Which is more correct? The average of those two will probably be better than just the one of them. In a five model ensemble four models are almost the same but one is not. Should that last model be equally weighted as the other four? IPCCs fourth assessment report was based upon a model ensemble of 22 models with equal weight leaving the future with a temperature rise in year 2100 at 2.8C (1.7 - 4.4C) in scenario SRESA1B. In this master thesis I look at a 24 model ensemble's ability to simulate the greenhouse effect and relating it to observations from NOAAs outgoing longwave radiation (OLR) and ECMWFs ERA40 surface air temperature. This is done in three ways, calculating G and two scatterplots. For each way a weight is calculated and the average of all three ways found. The weights are then applied to the model data for SRESA1B and a new temperature change for year 2100 is found. Supervisor: Eigil Kaas, NBI "
"Master Thesis by Jóhanna Rasmussen";"Klaus Mosegaard";"2010-06-24";"10:30";"";"";" lk. 86,  Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København 2100, lokale 86";"A Seismic Refraction/Reflection Study Along the FOERBAS96.01 Profile South East of the Faroe Islands ";" A Seismic Refraction/Reflection Study Along the FOERBAS96.01 Profile South East of the Faroe Islands Supervisors: Klaus Mosegaard and Jim Brown "
"Master Thesis: Emilie Hermansson";"Aksel Wallø Hansen, NBI";"2010-06-24";"14:15";"";"";"lk. 71, Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"A numerical study of a Petoraq-event in Greenland ";" A numerical study of a Piteraq-event in Greenland the talk will be in Swediskh ABSTRACT The ice sheet in Greenland and its topography largely influence the wind system and weather situation over Greenland. When air is cooled on the ice sheet it will descent down the slope towards the coastline due to the gravitational force and thus form a katabatic wind field. A Piteraq is a phenomenon which occurs when a low pressure system enhances the katabatic flow in Greenland. The most extreme Piteraq ever to be documented occurred at the east coast in Tasiilaq the 6th of February 1970, when wind gusts up to 72 m/s were measured. These winds nearly destroyed the entire town and it is crucial to be able to correctly forecast events like this. The aim of this master thesis is thus to compare the operational DMI-HIRLAM K05 hydrostatic weather prediction model with two non-hydrostatic HARMONIE models - one with the same horizontal resolution as the K05 model (5 km) and the other with a horizontal resolution of 2.5 km - in order to see which model best predicts this topographical event. The three models captured the location of the Piteraq well, but they all underestimated the wind speeds during the time when the storm had reached its most intense stage. The non-hydrostatic models proved to forecast the wind speeds better than the hydrostatic model. The wind speed predictions produced by the HARMONIE model with the coarsest resolution deviated 11.3 m/s from the maximum observed wind speed of 54 m/s at 18 UTC while the other HARMONIE model deviated 24.2 m/s and the K05 model 30.3 m/s. The hydrostatic approximation was probably not valid during the evening when the extreme wind speeds were observed which might have resulted in the inability of the K05 model to correctly forecast these wind speeds. Furthermore; the K05 model did not parametrise the gravity wave drag which might have been another reason for the underestimation of wind speed, neither did the HARMONIE model with horizontal resolution of 2.5 km which could have been the reason why it, despite its higher resolution, predicted a larger deviation from the observations than the other non-hydrostatic model did. Supervisors: Aksel Walløe Hansen NBI and Niels Woetmaann, DMI "
"Talk by Leo Kadanoff";"John Renner Hansen";"2010-06-24";"14:40";"";"";"Aud. A, Blegdamsvej 15";"Phase Transitions: Scaling, Universality and Renormalization, The University of Chicago and The Perimeter Institute Waterloo, Ontario, Canada ";" Abstract: In present-day physics, the renormalization method, as developed by Kenneth G. Wilson, serves as the primary means for constructing the connections between theories at different length scales. This method is rooted in both particle physics and the theory of phase transitions. It was developed to supplement mean field theories like those developed by van der Waals and Maxwell, followed by Landau. Leo P. Kadanoff Sharp phase transitions are necessarily connected with singularities in statistical mechanics, which in turn require infinite systems for their realization. (I call this result the extended singularity theorem.) A discussion of this point apparently marked a 1937 meeting in Amsterdam celebrating van der Waals. Mean field theories neither demand nor employ spatial infinities in their descriptions of phase transitions. Another theory is required that weds a breaking of internal symmetries with a proper description of spatial infinities. The renormalization (semi-)group provides such a wedding. Its nature is described. The major ideas surrounding this point of view are described including especially scaling, universality, and the development of connections among different theories. About the speaker: After receiving his PhD from Harvard University in 1960, Leo Kadanoff became a post doc with Niels Bohr in Copenhagen. Since then, for a period of 40 year, he has been among the leading physicists in the world in the development of modern physics. He has made seminal and important contributions to a large number of problems in modern physics, in particular on phase transitions and critical phenomena and in the theory for chaos and complex systems. In many cases, discoveries by Leo Kadanoff have initiated completely new activities and developments in physics worldwide. Leo Kadanoff has in Chicago created an excellent school in physics for graduate students and post docs, a school that is world famous. He has received many prizes and honors. "
"Specialeforsvar af Birte Martin-Bertelsen";"Per Hedegård";"2010-06-25";"13:00";"";"";"HCØ, Universitetsparken 5, 2100 Copenhagen Ø. D411";"Bayesiansk analyse af biologisk smÃ¥vinkelspredning ";"Bayesiansk analyse af biologisk smÃ¥vinkelspredning Specialeforsvar af: Birte Martin-Bertelsen "
"Master's thesis by Birte Martin";"Per Hedegård";"2010-06-25";"13:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D411";"Bayesiansk analyse af biologisk smÃ¥vinkelspredning ";" Bayesiansk analyse af biologisk smÃ¥vinkelspredning "
"Talk by Guido Burkard, University of Konstanza";"Karsten Flensberg";"2010-06-25";"14:15";"";"";"HCØ, Universitetsparken 5, 2100 Copenhagen Ø. D317";"The spin-valley blockade in carbon-based double quantum dots ";" The spin blockade effect in the electric conduction through two semiconductor quantum dots connected in series has allowed the monitoring of spin-breaking effects, notably single-spin rotations induced via external fields in electron spin resonance (ESR) and spin decoherence due to the hyperfine coupling to the nuclear spin environment. Electrons in double quantum dots in graphene and carbon nanotubes comprise a valley degree of freedom in addition to their spin. We show that this can lead to a spin-valley blockade which is sensitive to both spin and valley breaking effects. The hyperfine interaction due to residual 13C nuclear spins turns out to be both spin- and valley-breaking, while non-magnetic atomic impurities can lead to pure valley-breaking. We study the magnetic-field dependent leakage current in the spin-valley blockade. Finally, we also take into account the effect of the spin-orbit interaction in carbon-nanotubes and its influence on the leakage current. Talk by Guido Burkard, University of Konstanza "
"Master Thesis Middle-talk by Gonzalo de la Torre";"";"2010-06-28";"13:15";"";"";"Academy basement seminar room";"Title: Violation of local realism and the detection loophole ";" Abstract: I will talk about the basics of non-locality focusing on the difficulties one finds to prove it experimentally due to several loopholes. In particular, I will discuss the current theoretical approaches to close the detection loophole with hyper entangled photonic systems or mixed entangled atomic-photonic systems under different assumptions. Finally, if time allows, I will make an overview of the importance of closing the detection loophole, this is, the growing list of applications of nonlocality. Supervisor: Dr. Michael M. Wolf. Quantum Information Theory Group QUANTOP "
"Workshop at Dark Cosmology Centre";"";"2010-06-29";"10:00";"2010-07-05";"";"Dark Lounge";"SNe, GRBs and Dense Stellar Systems ";" SNe, GRBs and Dense Stellar Systems PROGRAMME Tuesday 29th June - Type Ia Supernovae 10:00 Daniel Kasen - The Physics of Type Ia SNe 10:35 James Guillochon - Double Degenerates as Type Ia SN Progenitors 10:50 Giorgos Leloudas - Supernova 2003hv 11:10 Tamara Davis - Type Ia SNe and cosmology (20 mins) 11:30-12:30 Informal Discussion (led by Justyn, Jesper, Enrico) Wednesday 30th June - Core-collapse Supernovae 10:00 Enrico Ramirez-Ruiz - SASIR 10:25 Giorgos Leloudas - Finding Supernovae with UltraVISTA 10:45 Justyn Maund - The Progenitors of Core-collapse Supernovae 11:15 Daniel Kasen - Pair Instability Supernovae 11:40-12:30 Informal Discussion (led by Justyn and Enrico) Friday 2nd July - Dense Stellar Systems 10:00 Enrico Ramirez-Ruiz -Dense Stellar Systems as Laboratories for Fundamental Physics 10:30 James Guillochon - Transients arising from tidal disruption of stars 11:10-12:30 Informal Discussion (led by Enrico) Monday 5th July - Gamma Ray Bursts 10:00 Berian James - The Physics Underlying Timescale Variability 10:20 Johan Fynbo - TBA 10:40-12:30 Open discussion (led by Enrico, Daniele and Johan) 14:00 Jill Naiman - Special Cake Talk: Accretion onto core potentials "
"Specialeforsvar v/ Mads Peter Steenstrup";"Jan W. Thomsen";"2010-07-29";"15:15";"";"";"Aud. 6, H.C. Ørsted Instituttet";"Investigation of Ultra Cold Magnesium Atoms - towards a new frequency standard ";" I mit speciale har jeg undersøgt ultra kolde magnesium atomer fanget i en magneto optisk fælde. Ved eksperimentelt arbejde med ultra kolde atomer arbejder man i et regime hvor kvantemikanikken sætter spillereglerne. Arbejdet i forskningsgruppen leder hen mod en redefinering af SI enheden for sekundet som i øjeblikket defineres af en hyperfinovergang i 133Cs. Præcis viden om de lavt liggende energiniveauer og ekspertise i af manipulere med atomerne er essentiel for denne udvikling. Jeg har foretaget de første direkte og hidtil mest præcise mÃ¥linger af isotop skiftet mellem 24Mg, 25Mg og 26Mg for 1P-1D overgangen ved 881 nm bølgelængde. Zeeman splitning af 24Mg blev observeret og forekomsten af fem resonans signaler kan beskrives udfra en superposition af atomernes tilstande. Derudover har jeg foretaget en række forsøg for at undersøge atomernes opførsel i den magnetisk optiske fælde for at kende perturbationerne og kunne manipulere atomerne effektivt. "
"Open arrangement on the occasion of the 50-years anniversary of the laser at the start of the ICPEPA 7 conference.";"Jørgen Schou og Martin Meedom Nielsen";"2010-08-05";"09:00";"2010-08-05";"10:15";"Lundbeck Auditoriet, Biocentret, Ole Maaløesvej 5, 2200 København N";"";"The 50-years anniversary of the laser will be celebrated at an open meeting at the beginning of the international conference, ICPEPA 7 (International Conference on Photo-Excited Processes and Applications) in the Lundbeck Auditorium at the Biocenter of University of Copenhagen. The group of Theodore Maiman at Hughes Research Laboratories, California turned the first laser 50 years ago. The anniversary is actually celebrated at several international conferences outside Denmark as well. The laser (Light Amplification by Stimulated Emission of Radiation) was considered as a scientific artifact at the discovery. Nobody expected the device to be known outside a small scientific community. However, today lasers are used everywhere in our society in our fast communication by optical fibers, as hardware parts in laser printers, DVD-drives and optical scanners in shops. They are also used for machining and welding of huge objects as ships in yards as well as for micromachining of small mechanical parts. In Physics the lasers has provided the researchers with a precise well-characterized light source which can produce ultra short pulses of extreme power and intensity, but also continuous beams of well-defined wavelengths. The high intensity can be utilized for production of new materials, e.g. in Solid Oxide Fuel Cells with a very complicated chemical composition, and to fast mass analysis of organic materials. In the last decades laser cooling was used to produce a new state of matter, the so-called Bose-Einstein condensate that has revolutionized our concepts in quantum mechanics. The conference ICPEPA is focusing on photo-excitations and the possible applications. It is a minor conference with about 120 participants, but it was only possible to get it to Denmark with coordinated effort headed by Senior Scientist at DTU Fotonik from four different laser groups in Denmark from the major Physics universities in Denmark, University of Copenhagen with Niels Bohr Institute, DTU Fotonik at the Technical University of Denmark, Institute of Physics and Astronomy, and Mads Clausen Institute at University of Southern Denmark. The conference has participants from 27 countries with Denmark, Germany and the East Asian states (Japan, Rep. Korea, and Taiwan) as the largest contributors. Since most of the participants are younger than the laser - and many young physicist cannot imagine a project without a laser - the local committee has therefore planned to use the opportunity to ask one of the veterans of laser science, prof. Sune Svanberg to give a talk: ""The laser- the first 50 years"" and this session will be a public session as an open arrangement. It is striking that a scientific discovery which initially was considered to be without any significance - 50 years after - has driven industrial enterprises to turnovers of billions of Euros and physics to extreme limits with the upcoming major European Facility XFEL (X-ray Free Electron Laser) in Hamburg as a milestone. Address: Lundbeck Auditoriet, Biocentret, Ole Maaløes vej 5, 2200 N. Tidspunkt: Mandag den 16. august, kl. 9:00 - 10:15 More information: Jørgen Schou, Tlf. 46 77 47 55 (josc@fotonik.dtu.dk) eller Martin Meedom Nielsen, Tlf. 35 32 04 27 (martin.meedom.nielsen@nbi.ku.dk). "
"Optical micro/nanofibers: fabrication, theory, and applications";"E. Polzik";"2010-08-10";"10:15";"";"";"Aud. A";"Talk by Dr. M. Sumetsky, OFS Laboratories (former Bell Labs), USA ";" Usually, an optical micro/nanofiber is a single-mode waveguide, which is fabricated from a standard telecom optical fiber by drawing and has a diameter from ~ 0.1 to ~1 micron. In this talk, basic methods of micro/nanofiber fabrication, theory, and applications are reviewed. In particular, the theory and experimental evaluation of adiabatic micro/nanofiber tapers are discussed. One of the interesting conclusions of the theory is the existence of the threshold nanofiber diameter below which a nanofiber does not transmit light. While the adiabatic micro/nanofiber tapers are the waveguides possessing macro-nonuniformities, not less important is the investigation of the microfiber micro-nonuniformities which are also considered both theoretically and experimentally. It is shown that the fundamental limit for the smallest transmission loss of micro/nanofibers is determined by the frozen-in capillary waves. Finally, several applications of microfibers in photonics are discussed. "
"Optical fiber/microfiber based high Q-factor resonators: theory and experiment";"E. Polzik";"2010-08-11";"10:15";"";"";"Aud. A";"Talk by Dr. M. Sumetsky, OFS Laboratories (former Bell Labs), USA ";" Postprocessing of an optical fiber by melting and drawing allows one to fabricate different types of miniature optical devices, e.g., micro/nanofibers and high Q-factor microsphere resonators. In this talk I briefly review these devices highlighting an adiabatic micro/nanofiber taper, microfiber loop resonator, microfiber coil resonator, as well as microbottle, microbubble, and microcylinder resonators. Bio Dr. M. Sumetsky graduated from St. Petersburg State University, Russia (1975) and has Ph.D. (1979) and D.Sc. (1989) degrees from the same University. In 1979 he joined the Physics Department of St. Petersburg University of Telecommunications and since 1995 worked at the Bell Labs, Lucent Technologies. After transition of the Optical Fiber Research Department of Bell Labs into the OFS Labs of the Furukawa Electric Company in 2001, he joined the OFS Labs. Dr. Sumetsky has more than 150 publications in optics and quantum mechanics. He is widely acknowledged as one of the pioneers of research in optics of micro/nanofibers and microresonators. "
"Talk by Titoo Jain";"Thomas Bjørnholm";"2010-08-13";"10:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø. Lokale D317";"Gold Nanorods for Single Molecule Electronics, 4+4 PhD Midway - and Master Thesis Defense ";" Gold Nanorods for Single Molecule Electronics 4+4 PhD Midway - and Master Thesis Defense The work to be described in this oral defense serves as a precursor for my final PhD thesis to be submitted in 2012. Furthermore, it will fulfill the requirements for the title Master of Science in nanoscience at the University of Copenhagen, Denmark. The research is focused on developing novel ways to fabricate single-molecule junctions (nanogaps). This is done by employing synthesis of single-crystalline one-dimensional gold nanorods that can potentially act as next generation electrodes. The experimental labor has mainly been carried out at the Nano-Science Center & Department of Chemistry at the University of Copenhagen in the period Sep. 2008 - Aug. 2010. Results from my 6 month stay at IBM Research Laboratory in Zürich, Switzerland, together with data acquired by collaborating with colleagues at Chalmers University of Technology in Gothenburg, Sweden, will also be briefly described. "
"Cosmology workshop at the NBIA";"P. H. Damgaard, P. Naselsky, H. Collins, and S. Nesseris";"2010-08-16";"10:00";"2010-08-20";"18:00";"Auditorium A";"Cosmology workshop ""Confronting theory with observations"" at NBIA ";" We will be organizing the Cosmology workshop ""Confronting theory with observations"" at the Niels Bohr International Academy from 16th to 20th August, 2010. The atmosphere will be lively and informal, with relatively few talks each day, to provide plenty of time for discussion and collaboration among the participants. Local organizers: P. H. Damgaard, P. Naselsky, H. Collins, and S. Nesseris. This workshop is sponsored by UniverseNet, a Marie Curie Research Training Network. Additional support has been provided by the Discovery Center and the Niels Bohr International Academy. Dates: from 16 August 2010 10:00 to 20 August 2010 18:00 Location: Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen Ø, Denmark Room: Auditorium A You can find more information and also register on the workshop website: https://indico.nbi.ku.dk/conferenceDisplay.py?confId=179 Speakers (so far): • Lars Bergström, Stockholm University • Peter Coles, Cardiff University • Alexander Dolgov, ITEP, Moscow & Ferrara University • Steen Hannestad, Aarhus University • Alan Heavens, University of Edinburgh • Sabino Matarrese, University of Padua • Anupam Mazumdar, Lancaster University • Slava Mukhanov, Ludwig-Maximilians-Universität München • Hiranya Peiris, University of Cambridge • Will Percival, University of Portsmouth • Leandros Perivolaropoulos, University of Ioannina • Syksy Rasanen, University of Helsinki • Subir Sarkar, University of Oxford • Shinji Tsujikawa, Tokyo University of Science "
"Talk by Bill Atkinson, Trent University, Canada";"Brian M. Andersen";"2010-08-17";"14:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø lokale D210";"Impurities in Strongly-Correlated Materials: Understanding Density of States Anomalies ";"Strongly-correlated materials have held the attention of the physics community for decades, first, because they lie outside the standard model of metals and insulators and, second, because they exhibit a range of new properties, such as high temperature superconductivity. Many of these materials have their electronic properties tuned by chemical doping, and there is a growing awareness that the disorder introduced by chemical doping can have important consequences. In this talk, I will focus on a recent prediction that a novel zero bias anomaly (ZBA) should appear in the density of states. A ZBA is a suppression of the density of states at the Fermi energy, due in this case to the simultaneous presence of disorder and interactions. I will explain why the ZBA is not expected on the basis of conventional Altshuler-Aronov theory, and then discuss our attempts to understand its underlying physics in strongly-correlated models. I will show that strong correlations lead to a new mechanism for suppressing the density of states at the Fermi level when disorder is present. "
"Causal Dynamical Triangulations, Mid-term colloquium by Laura Gava";"C. Kristjansen";"2010-08-18";"10:15";"2010-08-18";"11:00";"Aud D, Blegdamsvej 17";"Causal Dynamical Triangulations, Mid-term colloquium by Laura Gava ";" In order to obtain a theory of quantum gravity for two-dimensional spacetimes with Lorentzian signature, Causal Dynamical Triangulations (CDT) sums over all possible geometries using triangles as ""building blocks"" while imposing a causal structure on them. The Hausdorff dimension is found to be 2, contrasting with two-dimensional Euclidean quantum gravity, which has a fractal dimension of 4. A more general version of CDT englobes topology changes of space, thus allowing for the creation of baby universes. By further allowing for the universes to merge, CDT has also been formulated as a string field theory. Quantum gravity in two-dimensions can be exactly solved and its tools may be useful in a theory of quantum gravity of higher dimensions. In this talk, I will give an overview of the construction of CDT as well as some of its results. Supervisor: Jan Ambjørn "
"Master Thesis Defense by Bryan Haddock";"Robert Feidenhans'l";"2010-08-20";"14:15";"";"";"D317, HC Ørsted Instituttet";"Calculating T1 Values to Determine Brain-Oxygenation Levels Using Magnetic Resonance Imaging (MRI) ";" "
"Kollokvium: Andreas Lemark";"Centre for Ice and Climate";"2010-08-23";"13:00";"";"";"Rockefeller, Juliane Maries Vej 30, room 235";"Om analyse og boring af iskerner ";"Om analyse og boring af iskerner Supervisor: Dorthe Dahl-Jensen I foredraget vil jeg gennemgå nogle af de mest anvendte metoder til analyse af iskerner, heriblandt ECM (Electrical Conductivity Measurements), måling af urenheder i isen og isotopmålinger. Disse metoder bruges både til at tidsfæste iskernen og til at studere mekanismerne i fortidens klima. Jeg vil også fortælle om de praktiske forhold der arbejdes under når en iskerne bores op, ved eksempler fra Flade Isblink lejren i nordøst Grønland. "
"Synthetic Biology International Workshop Copenhagen 2010";"Gitte Frandsen";"2010-08-25";"";"2010-08-27";"";"Nano-Science Center, University of Copenhagen, Denmark";"Leading scientists in the emerging field of Synthetic Biology at an international workshop in Copenhagen ";"The University of Copenhagen has recently launched a new research program in Synthetic Biology. In cooperation with the University of California at Berkeley, we now bring together leading scientists in the emerging field of Synthetic Biology at an international workshop in Copenhagen. More information and registration. "
"Master Thesis: Andreas Lemark";"Centre for Ice and Climate";"2010-08-25";"13:00";"";"";"Rockefeller, Juliane Maries Vej 30, room 235";"En undersøgelse af Flade Isblink iskappen ved brug af en simpel isflydemodel ";"En undersøgelse af Flade Isblink iskappen ved brug af en simpel isflydemodel Resume I år 2006 blev en iskerne boret på iskappen Flade Isblink (81.3N, 15.7W), der befinder sig på halvøen Kronprins Christians Land i nordøst Grønland. I dette speciale forsøges Flade Isblinks opbygningshistorie modelleret med en simpel 1D flydemodel. Forskellige kørsler afprøves der inkorporerer data fra iskerneboringen. Det ældste referencepukt findes i en dybde af 384 meter hvor rester fra den Islandske vulkan Eldgjas udbrud i år 934 findes. Alderen af iskappen fastslås at være et sted mellem 2800 og 4000 år, sandsynligvis nærmere den yngre værdi. Et studie af det seneste årtusindes klimahistorie i området laves herefter med en tidsskala opnået fra modelleringen. Her ses nogle af de klimatiske forandringer der også er velkendte fra andre klimastudier. Abstract In 2006 an ice core was drilled in north eastern Greenland on the ice cap of Flade Isblink (81.3N, 15.7W) located on the peninsula of Kronprins Christians Land. In this thesis a 1D flow model is applied to the buildup of the ice cap that incorporates the data retrieved from the ice core. The oldest reference point in the ice core is evidence of an eruption by the Icelandic volcano Eldgja in 934 A.D. found at a depth of 384 meters. Different scenarios are presented, bounding the age of the ice cap between 2800 and 4000 years, most likely nearer the younger value. A climatic study is then done with a time scale acquired from the modelling, showing some of the notable climatic events that have taken place during the past millennium. Supervisor: Dorthe Dahl-Jensen Forsvaret foregår på dansk. Der er reception efter forsvaret. "
"Master Thesis Defence by Conzalo de la Torre Carazo";"Michael Wolf";"2010-08-25";"15:00";"";"";"Aud A";"Title: Violation of local realism and the detection loophole ";" This thesis addresses non-locality, a property of nature closely related to entanglement which entails the largest departure from the classical world and that lies at the heart of the power of quantum information and computation. In particular, we focus on the difficulties one finds to prove it experimentally due to several loopholes. In particular, we discuss the current theoretical approaches to close the detection loophole with hyper entangled photonic systems or mixed entangled atomic-photonic systems under different assumptions. We motivate the work by giving a brief review of the applications that non-locality has when achieved in a certified loophole-free way such as device-independent cryptography or guaranteed randomness. We give bounds to the minimum detection efficiency needed for different scenarios under realistic experimental conditions and finish with an intriguing observation about the possible relation of these bounds with the ones achieved in more general no-signalling theories. "
"NBIA Colloquium";"P.H. Damgaard";"2010-08-25";"1:15 pm";"";"";"Aud. A, Blv.";"David G. Stork: When Computers Look at Art ";" David G. Stork, Ricoh Innovations and Stanford University When computers look at art: Image analysis in humanistic studies of the visual arts New computer methods have been used to shed light on a number of recent controversies in the study of art. For example, computer fractal analysis has been used in authentication studies of paintings attributed to Jackson Pollock recently discovered by Alex Matter. Computer wavelet analysis has been used for attribution of the contributors in Perugino's Holy Family. An international group of computer and image scientists is studying the brushstrokes in paintings by van Gogh for detecting forgeries. Sophisticated computer analysis of perspective, shading, color and form has shed light on David Hockney's bold claim that as early as 1420, Renaissance artists employed optical devices such as concave mirrors to project images onto their canvases. How do these computer methods work? What can computers reveal about images that even the best-trained connoisseurs, art historians and artist cannot? How much more powerful and revealing will these methods become? In short, how is computer image analysis changing our understanding of art? This profusely illustrate lecture for non-scientists will include works by Jackson Pollock, Vincent van Gogh, Jan van Eyck, Hans Memling, Lorenzo Lotto, and others. You may never see paintings the same way again. "
"Structure and dynamica of crystalline nano-systems";"Robert Feidenhans'l";"2010-08-26";"11:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, Aud. 3";"PhD defence by Simon Oddsson Mariager ";" Abstract: X-ray research is facing a new era with the advent of the free electron lasers (FELs). The first experiments are being conducted at LCLS in California while the European XFEL and Japanese compact SASE source are both under construction. The x-ray bunches of the FELs have a time resolution on the order of 100fs and can be focused to hundreds of nanometer, properties which naturally lends the FELs to both time-resolved pump-probe experiments, studies on the nanoscale and combinations thereof. Within the field of x-ray diffraction both types of experiments have been the subject of the thesis work presented here. In the first experiments we used surface x-ray diffraction techniques and reciprocal space mapping to study the structure and growth of semiconductor nanowires. The second type of diffraction experiments are time-resolved laser pump x-ray probe experiments performed at the FEMTO beamline of SLS. We studied the electronic deformation in metals by measuring and modelling laser induced strain waves in Au and found a weak electronic contribution to the expansion. In addition we studied the structural part of the anti-ferromagnetic to ferromagnetic phase transition in FeRh. Finally the two main subjects are combined in a time-resolved x-ray study of laser excited acoustic oscillations in InAs nanowires. We measured both the absolute motion of the wires as well as the period of the oscillations, and are thus able to test the predictions made by classical continuum elasticity theory. In this talk I will give a brief explanation of the diffraction principles for reciprocal space mapping derived and applied in all of this work, but otherwise focus on the time-resolved x-ray studies on metals and nanowires. PhD defence by Simon Oddsson Mariager "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-08-26";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"Ratindranath Akhoury (U. Michigan): Modification of the usual causality condition in Quantum Field Theory: A dynamical coupling constant theory ";" Ratindranath Akhoury (U. Michigan) Title: Modification of the usual causality condition in Quantum Field Theory: A dynamical coupling constant theory "
"Talk by Ullrich Pietsch, University of Siegen";"Robert Feidenhans'l";"2010-08-26";"15:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, D317";"X-RAY STRAIN EVALUATION AT INDIVIDUAL SEMICONDUCTOR NANOWIRES ";" Semiconductor nanowires (NW) are of particular interest due to the ability to synthesize single-crystalline 1D epitaxial structures and heterostructures in the nanometer range. The superior electrical and optoelectronic properties of semiconductor nanowires make them very desirable as building blocks in future nanoscale devices. Typically, transmission electron microscopy can be used to inspect individual NWs. However, this approach is destructive and allows the inspection of a very limited number of nanowires only. Complementary, recent developments in x-ray optics allow to perform diffraction studies on individual nano-objects. In this contribution we present the methodic of X-ray single nanowire inspection using the micro-focus setup available at the ID1 beamline of ESRF. As examples of application we show strain analysis at individual GaAs NW grown on patterned GaAs[111] substrate [1], Au- seed assisted GaAs NW grown on Si[111] and catalyst free GaAs NWs growth on Si[111] demonstrating that the NWs may differ in shape, morphology and strain among each other. Particular effort was spent to investigate the early stage of NW growth and to understand more about how the huge lattice mismatch between NW and substrate is released. Talk by: Ullrich Pietsch - University of Siegen, Festkörperphysik, Siegen, Germany "
"Master thesis by Leif Skovbo";"Eigil Kaas";"2010-08-30";"14:00";"";"";"Niels Bohr Institutet, lokale 71 Juliane Maries Vej 30, 2100  København Ø";"Weighting of an ensemble of climate models ";" Weighting of an ensemble of climate models Abstract: When people talk about climate change, one question is always: 'How warm will it be in the future?'. To answer this question some of the most important tools are the general circulation models simulating the atmosphere and the ocean, AOGCMs. One model predicts one outcome, and the next model predicts a different outcome. Which is more correct? The average of those two will probably be better than just the one of them. In a five model ensemble four models are almost the same but one is not, so should that last model be equally weighted as the other four? IPCCs fourth assessment report was based upon a model ensemble of 23 models with equal weight leaving the future with a temperature rise in year 2100 at 2.8C (1.7 - 4.4C) in scenario SRESA1B. In this master thesis I look at a 24 model ensemble's ability to simulate the greenhouse effect, and relating it to observations from NOAAs outgoing longwave radiation (OLR) and ECMWFs ERA40 surface air temperature. This is done in five methods, one calculating the greenhouse effect, G, and four different scatterplots, and for each method a weight is calculated for all models and averages are found for methods of global mean and zonal mean greenhouse effect. The weights are then applied to modify the model data for SRESA1B and a new temperature change for year 2100 is found. Supervisor: Eigil Kaas, Niels Bohr Institute "
"Master Thesis Defense by Laura Gava";"Jan Ambjørn";"2010-08-31";"16:00";"";"";"Aud. D, Blegdamsvej";"Thesis title: Two-Dimensional Quantum Gravity ";"Abstract: Causal Dynamical Triangulations is a theory of quantum gravity that imposes a causal structure on the triangulations used to regularize two-dimensional spacetimes. By allowing for space to split and merge, Causal Dynamical Triangulations has been formulated as a String Field Theory, which can also be described by a matrix model. Via this matrix model, a sum over topologies has been performed. In my thesis, I review the development of CDT, as well as some of its results. The defence will focus on the sum over all genera for two-dimensional spacetimes. Advisor: Jan Ambjørn "
"GEOMAPS Lectures";"Niels Obers";"2010-09-01";"14:00";"";"";"Aud. D, Blegdamsvej 17";"Yuri Makenko (Moscow): The loop equation and its contemporary applications I ";" Yuri Makenko (Moscow) The loop equation and its contemporary applications I "
"GEOMAPS Lectures";"Niels Obers";"2010-09-02";"11:00";"";"";"Aud. D, Blegdamsvej 17";"Yuri Makenko (Moscow): The loop equation and its contemporary applications II ";" Yuri Makeenko (Moscow) The loop equation and its contemporary applications II "
"Master thesis by Steen Roswall";"Morten Bo Madsen";"2010-09-02";"13.15";"";"";"lk. 71, Rockefeller Komplekset, Juliane Maries Vej 30, 2100  København Ø";"Red Dust, A study of the magnetic properties of Martian soil and Mars analogue samples using the MECA microcopy station ";" Red Dust A study of the magnetic properties of Martian soil and Mars analogue samples using the MECA microscopi station I 2007 landende Phoenix Mars Lander pÃ¥ Mars og den medbragte bl.a. instrumentet MECA (Microscopy, Electrochemistry and Conductivity Analyzer). Dette instrument var designet til at studere Mars' overflade pÃ¥ mikroskala niveau. Ved hjælp af en robotarm kunne prøver af overflade materialet deponeres pÃ¥ nogle magnetiske overflader i MECA'en og studeres nærmere. PÃ¥ Imperial College i London er opstillet en kopi af MECA og med denne kan Mars analoge jordprøver analyseres. I specialet er data fra Phoenix Mars Lander sammenlignet med data fra en hÃ¥ndfuld prøver i et forsøg pÃ¥ at finde ud af Mars-støvets magnetiske egenskaber ved. Fra tidligere undersøgelser vides det at mætningsmagnetiseringen for støvet ved Phoenix landingssted ligger i intervallet 0,5-2 Am2/kg og det er mÃ¥let at forbedre bestemmelsen af og troværdigheden af dette interval. Vejledere: Morten Bo Madsen, Kristoffer Leer, Niels Bohr Instututet "
"Ph.D.-defense by Rut Jesus";"Claus Emmeche";"2010-09-04";"13:00";"";"";"Auditorium A, Blegdamsvej";"Cooperation and Cognition in Wikipedia Articles - A data-driven, philosophical and exploratory study ";"Abstract: Wikipedia has created and harnessed new social and work dynamics, which can provide insight into specific aspects of cognition, as amplified by a multitude of editors and their ping-pong style of editing, spatial and time flexibility within unique technology-community fostering features. Wikipedia's motto ""The Free Encyclopedia That Anyone Can Edit"" is analyzed to reveal human, technological and value actors within a theoretical context of distributed cognition, cooperation and technological agency. In the Data-driven studies using data from Wiki log pages, network visualization and bicliques are used and developed to focus closer on the process of collaboration in articles and meta-articles, and inside the article ""Prisoner's dilemma"" and the policy article ""Neutral Point of View"". The several tools used reveal clusters of interest, dense areas of coordination, a blend between coordination and direct editing work, and point to Wikipedia's dynamic stability in content and form. In the philosophical-cognitive studies, a distinction between Cognition for Planning and Cognition for Improvising is proposed to account for Wikipedia's success and mode of editing whereby many small edits are used for its improvement. In the exploratory part an installation of a 'live-Wiki' 'Our Collnnective Minds' piece reflects on several aspects of Wikis, free culture, open source and Do-It-Yourself by engaging in the debate in a more creative and participative form. These studies contribute to constructing an ecology of the article, a vision of humanities bottom-up, and a better understanding of cooperation and cognition within sociotechnological networks. The thesis can be downloaded from: http://www.nbi.dk/~vulpeto/jesus_thesis_final.pdf Assessment committee: Associate Professor Lisbeth Klastrup, Digital Culture & Mobile Communication Research Group, IT University of Copenhagen (chairman); Professor Stevan Harnad, School of Electronics and Computer Science University of Southampton; Professor Juha Suoranta, Department of Education, University of Tampere Co-chairman [ordstyrer]: associate professor Klemens Kappel, Department of Media, Cognition and Communication, University of Copenhagen Supervisor: Associate professor Claus Emmeche, Center for the Philosophy of Nature and Science Studies, University of Copenhagen. Total programme: After the defense, there will be a reception in auditorium C, planned to start around 15:30. Please tell us (by email to Di Ponti [ vulpeto [at] gmail.com ]) about your presence here, so as to estimate the volume of wikisoup. After the reception, at 16:30 (estimated) to 18:30, we hope also to see you at a Meta-Ph.D. Performance. "
"Tiltrædelsesforelæsning af adjungeret professor i Space Science Peter Jakobsen";"Jens Paaske";"2010-09-15";"13:15";"";"";"Aud. 3, H.C.Ørsted Institutet, Universitetsparken 5, 2100 København Ø";"Big (Space) Science: The Hubble and James Webb Space Telescopes ";" Abstract: The Hubble Space Telescope, launched in 1990, and its successor the James Webb Space Telescope due to be launched in 2015, are among the most ambitious and expensive scientific space projects ever undertaken. Both missions have significant levels of European participation. In this talk I will attempt to outline the astrophysical motivation for placing such large astronomical telescopes in space, and provide a physicist's view of some of the associated technical challenges. Some key results obtained with the Hubble Space Telescope, and how these have influenced the capabilities of its successor, will also be described. About the speaker: Dr. Peter Jakobsen is the European Space Agency's (ESA's) Project Scientist for James Webb Space Telescope (JWST) and its instrument NIRSPEC. He is affiliated to ESA's ESTEC division in Nordwijk, the Netherlands. In addition to his administrative and technical experience at ESA, he is also an outstanding, senior scientist who has made very significant contributions on areas as diverse as the discovery of the epoch of He re-ionisation, the cosmic UV background, and studies of SN1987A "
"PhD defense by Alexander Hunziker";"BioComplexity";"2010-09-17";"14:00";"";"";"Auditorium A, Blegdamsvej 17, 2100  Copenhagen Ø";"Sense & Sensitivity: Regulation of genes in good and bad times ";" This PhD thesis describes three research projects which, along different lines, looked into how cells integrate external signals. Some projects being pure modelling work and others involving laboratory work, this thesis is at the interface of theory and experiments. In the first project, we engineered E. coli with custom made promoters with the aim of getting the cells to integrate two external signals according to certain logics belonging to the class of Boolean functions. We wanted to find out how diverse a set of logics we could obtain by exploiting only mechanisms of transcription regulation. We were able to implement 12 of the 16 Boolean functions and conclude that transcription regulation provides cells with a very flexible toolbox to adapt to new environmental conditions. The second project looks at a central part of many mammalian cells' stress response system, the p53 pathway. Even though all cell stresses are integrated through the same central node, the p53 protein, the pathway can trigger responses which are very diverse and stress-specific. We argue that it is the particular design of the p53-MDM2 feedback loop, with a negative feedback featuring a relatively slow transactivation leg and a fast inhibition leg, which makes this possible. Finally, the third project looks at the timing of gene expression in E. coli's galactose utilisation system, as a culture of cells grow to stationary phase on a limited galactose pool. It is assumed that the structure of gene regulatory networks in an organism evolves to deal with the kind of environmental situations it most frequently encounters. By observing the dynamics of how the culture uses up the given sugar pool, we deduce that E. coli evolved to live in environments which feature unpredictable food availability, as opposed to so-called feast and famine cycles. Supervisors: Mogens Høgh Jensen, Sabolcs Semsey & Sandeep Krishna "
"Numerical studies on the Heisenberg Antiferromagnet on a Square Lattice";"Kim Lefmann";"2010-09-17";"15:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D411 ";"Master thesis defense by Torsten Tranum Rømer ";"The quantum mechanical Heisenberg antiferromagnet on the square lattice has been investigated by exact diagonalization studies. The results are compared to both numerical and experimental results from the literature with special attention to neutron scattering data for CFTD obtained by Christensen et al. The analysis concentrates on a experimentally observed anomaly in both energy and intensity at the point (π, 0) in the two dimensional Brillouin zone. The results of exact diagonalization were found to model neutron scattering data and further suggested a possible explanation of the experimentally observed intensity anomaly. Master thesis defense by Torsten Tranum Rømer "
"Theoretical High Energy Seminar";"E. Bjerrum-Bohr";"2010-09-21";"14.15";"";"";"Aud. A, Blv";"An Overture to Quantum Superstring in AdS_5 x S^5, Yoichi Kazama, U.Tokyo, Komaba ";" Yoichi Kazama, U.Tokyo, Komaba Title: An Overture to Quantum Superstring in AdS_5 x S^5 Abstract: As a step towards understanding the quantum closed string in AdS_5 x S^5, one of the crucial unsolved problems in AdS/CFT correspondence, we study the quantum superparticle in such a curved background. We will describe how to quantize and obtain the spectrum of the system exactly, together with the explicit wavefunctions, by making use of the powerful superconformal symmetry of the system. The spectrum precisely matches that of supergravity, including all the Kaluza-Klein excitations. "
"Master thesis by Torsten Lauridsen";"Robert Feidenhans'l";"2010-09-21";"15:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø D317";"X-ray and neutron reflectivity on nanodiscs below the air-water interface ";"In my thesis I describe a method for adsorbing nanodiscs in a well defined monolayer just below an air-water interface. The layer has been analyzed using x-ray and neutron reflectivity to determine the layer dimensions. The x-ray reflectivity measurements have been carried out using a rotating anode x-ray source at the H.C. Ørsted institute, University of Copenhagen, and the neutron reflectivity measurements have been conducted at the Inter Beamline, by the ISIS neutron facility near Oxford, England. Master thesis by Torsten Lauridsen "
"String Study Group";"C. Kristjansen";"2010-09-22";"11:15";"2010-09-22";"12:30";"Fb6";"H.Johansson (Saclay) presents 1008.2958 ";" H. Johansson (Saclay) presents the paper 1008.2958 [hep-th] by Arkani-Hamed et al. entitled ""The All-loop Integrand for Scattering Amplitudes in Planar N=4 SYM."" "
"Master Thesis by Hjalte Frellesvig";"Anders Sørensen";"2010-09-23";"15:00";"";"";"Aud. M";"Spin-squeezing in Bose-Einstein condensates ";"In this thesis a theory for steady-state squeezing of an abstract collective spin-variable is developed for particles in a Bose-Einstein condensate. Such a theory can be put to direct use in the field of quantum-metrology, since squeezed states can help improve the precision of atomic clocks. In the two-mode approximation it is easy to see that a steady-state Bose-Einstein condensate will be spin-squeezed, since the Hamiltonian describing such a system has the maximally squeezed state as the lowest energy eigenstate. The calculation central to this thesis is done using a Bogoliubov transformation of perturbations of the quantum-field operator describing the particles in the condensate. This transformation will diagonalize the Hamiltonian, which enables us to find an (almost) complete set of eigenvalues and eigenstates. These states can be used to calculate the expectation values of the angular momentum operators, from which the spin-squeezing can be calculated. The atoms in the condensate are described using two constants U and Uab proportional to the scattering lengths for atoms of equal and different spin respectively. The result of a numerical implementation of the theory is that for zero temperature the optimal atoms have U ≈ Uab ≈ 0. This is contrary to the case of higher, physical temperatures, where atoms with U >> Uab and U + Uab >> 1 will maximize the squeezing.Further results are that the most spin-squeezing is produced for as large a particle number and as low a temperature as possible. "
"Talk by John Chiang, Ass. Professor, University of California, Berkeley";"Centre for Ice and Climate";"2010-09-24";"13:00";"";"";"Room 235, 3rd floor, Juliane Maries Vej 30";"Atmospheric teleconnections of North Atlantic cooling to the Tropics and Southern Hemisphere. ";"Atmospheric teleconnections of North Atlantic cooling to the Tropics and Southern Hemisphere Abstract The realization from paleoclimate studies that North Atlantic cooling can significantly alter the global climate has motivated a number of modeling and theoretical studies over the last few years to understand how and why these teleconnections come about. In this talk, I'll cover some of these developments, specifically focusing on how the tropical climate is impacted. I'll also introduce some recent results that suggest an atmospheric teleconnection from North Atlantic cooling to the southern hemisphere midlatitude westerlies, via changes to the tropical Hadley circulation. There are implications of these teleconnections for interpreting past and present climate change scenarios, and I'll touch on some of them in conclusion. "
"Elite PhD School";"C. Kristjansen";"2010-09-27";"10:15";"2010-10-01";"16:00";"Aud A";"Particles from strings and vise versa -- Elite PhD school on integrability in the AdS/CFT correspondence ";" This elite PhD school will give PhD students and other interested researchers an introduction to integrability in the AdS/CFT correspondence. Topics will include amplitudes in N=4 SYM, the thermodynamical Bethe ansatz and the Y-system. You can find more information and also register on the workshop website "
"Junior Faculty meeting September 29th";"Junior Faculty";"2010-09-29";"14:15";"";"";"NBI canteen at Blegdamsvej";"Junior Faculty meeting on Wednesday 29 at 14:15 in the NBI canteen at Blegdamsvej ";" We are having a meeting on Wednesday (29th) at 14:15 in the NBI canteen. Agenda: 1) NBI director John Renner Hansen will explain the plans for the new Niels Bohr Science Park and the moving plans. 2) David Balslev-Clausen will present the newly published vision report ""Niels Bohr Institute toward 2013"". He will go over the parts of the vision relevant to Junior Faculty members, along with a description of the process taken in its formulation, and the future activities planned by the vision group in realizing the formulated vision. 3) Junior Faculty has been asked to arrange the NBI Christmas Lunch the 10th of December, so if anyone wants to help arrange entertainment or help put up decoration and so on, they can volunteer. 4) Election for one seat in the Junior Faculty executive committee (see below) 5) Fridays Lounge will start again, it will be a Junior Faculty get-together every 3 months just after work. The first is being planned for October and will include live music and beer. 6) Miscellaneous Just after the meeting, there is a meeting at the same place for both the Junior Faculty and Senior Faculty, where it will be discuss if any part of Blegdamsvejs departments will stay at the adresse. If there is anyone who are a strong believer for not moving all of Blegdamsvej departments to the new science park, then please contact Junior Faculty (line@nbi.ku.dk), and you can make a presentation for this meeting, as both Junior and Senior Faculty have a hard time finding anyone. We very much hope to see you there! Sincerely, The Junior Faculty Executive Committee (Line Drube, Kennet Harpsøe and Jay Armas) "
"Master Thesis  by Jesper Skottfelt";"Per Kjærgaard Rasmussen";"2010-10-01";"14:00";"";"";" Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København 2100, Lokale 016";"Concept Study of a Scanning Space Telescope ";" Concept Study of a Scanning Space Telescope Abstract: A scanning space mission is studied, based on a 3.5 meter space telescope, equipped with a camera employing 1000 photon counting detectors with a spatial resolution of 0.05 arcseconds. The mission will scan the obtainable sky in about 14 days and in a 10 year mission lifetime, the full sky will therefore be scanned in the order of 200 times. The limiting AB-magnitude per scan is found to be about 25, while it for the full mission goes beyond 29. Using both visual and near-infrared detectors, the wavelengths from 200 to 1700 nm will be covered. A number of major science drivers are presented along with proposed scanning strategies. Further, the payload is studied along with several elements of the platform of the spacecraft and a simulation of a possible orbit is presented. Supervisor: Per Kjærgaard Rasmussen, Co-supervisor: Michael Ingemann Andersen "
"Talk by Daniel Salart University of Geneva";"Eugene Polzik";"2010-10-04";"11:15";"";"";"Aud. A";"Bell experiments to test the non-locality of quantum correlations ";"""Neglecting loopholes in their interpretation, all previously performed Bell experiments have helped to confirm quantum theory, but only when gravity is negligible. None of them attempted to create significant variations in the local gravitational fields at the time and locations where the measurements are performed. In this experiment, the detection of each particle triggers the displacement of macroscopic masses that modify their surrounding gravitational fields. This allowed us to test the hypothesis that says that the collapse of the wave-function is induced by gravity. This experiment also confirmed that the correlations between two space-like separated events that are observed in Bell experiments can not be explained by subluminal communication. However, it could still be possible that an unknown influence travelling between the events at a speed faster than light induces the collapse of the wave-function. If we consider, for a moment, that this hypothetical influence is a real phenomenon, it is logical to assume that it has a speed; and this speed must be defined in some universal privileged reference frame. In this experiment, we also set a lower bound on the value of this speed, confirming the nonlocality of quantum correlations."" "
"String Study Group";"";"2010-10-05";"13:15";"2010-10-05";"14:30";"";"R. Monteiro (NBIA) presents his paper 1008.1070 entitled ""On three-point functions in the gauge/gravity dualilty"". ";" R. Monteiro (NBIA) presents his paper 1008.1070 entitled ""On three-point functions in the gauge/gravity dualilty. "" "
"Master Thesis Defence by Tolga Bagci";"Eugene Polzik";"2010-10-06";"14:15";"";"";"Aud A";"Title: Cavity Optomechanics with High Q Mechanical Resonators ";" The thesis presented here deals with the optomechanical interaction between a mechanical resonator(membrane) and radiation pressure. A two color-probing scheme is proposed for reading out the displacement of a membrane sitting inside a high-finesse cavity, in order to eliminate technical noise as a common-mode signal. In pursuit of a long-term goal in which we hope to see quantum correlations between light and a high Q micromechanical resonator cooled down to the ground-state, an experimental work has been carried out to characterize the eigenfrequencies and Q-factors of the vibrational modes for SiN(stoichiometric form) and GaAs membranes. Both thermal spectrum and mechanical ringdown measurements were performed and the results were compared. The author reports impressive Q-factors(dominantly dependent on clamping loss) for SiN membranes, exceeding 10^6 at room temperature, at frequencies in MHz regime. For the GaAs membrane, measurements yielded Q values exceeding 10^5 in 20 kHz-70 kHz frequency range, including one outstanding mode with a Q-factor of≈10^6 and rendering the possibility for more interesting experiments due to the unique properties of GaAs. The master thesis is rather focused on the characterization measurements on two different SiN membranes which can be regarded as prerequisite steps for our prospective optical experiments with mechanical resonators. "
"Conference on Genomes and the Synthesis of Life";"Claus Emmeche & Rasmus Grønfeldt Winther";"2010-10-07";"09:00";"2010-10-08";"17:00";"Niels Bohr Institute, Auditorium A";"Technological, Philosophical, and Cultural Aspects (organized by PHIS and CPNSS) ";" Genomics, proteomics, and synthetic biology are advancing at an ever-accelerating pace. Data, technology, and promises issue forth from these efforts. This conference describes current scientific progress in genomics and the synthesis of life, and then examines these advances from a philosophical and cultural point of view. How are bottom-up (reductionist-analytic) and top-down (holistic-synthetic) methodologies used in this research? What role do mathematical models (e.g., nonlinear dynamics, agent-based models, and network theory) play in contemporary biotechnological efforts? Does physics influence biology? How might we change the way that we look upon ourselves, our capacities, and our potentials, if we were able to synthesize life, or fully interpret the genome, or both? This conference brings together top researchers in the biological sciences and in the philosophy of science, to explore these questions. The first day focuses on philosophical and cultural matters (""philosophy & culture""), the second day on technological progress (""biology""). There is a roundtable discussion at the end of each day. On 7th and 8th October 2010 Niels Bohr Institute, Auditorium A Blegdamsvej 17, 2100 Copenhagen Speakers: Mark A. Bedau, Reed College, USA European School of Molecular Medicine, Italy University of Southern Denmark John Dupré, University of Exeter, U.K. Peter Godfrey-Smith, Harvard University, USA Gerd Müller, University of Vienna, Austria Steen Rasmussen, University of Southern Denmark Rasmus Grønfeldt Winther, University of California, Santa Cruz, USA CPNSS, University of Copenhagen Schedule 7/10-8/10 2010 7.10.10: Philosophy and Culture 9.00-9.30 Registration 9.30-11.00 Peter Godfrey-Smith 11.00-11.20 Pause 11.20-12.50 Rasmus Grønfeldt Winther 12.50-14.00 Lunch 14.00-15.30 John Dupré 15.30-16.00 Pause 16.00-17.00 Roundtable 8.10.10: Biology 9.30-11.00 Steen Rasmussen 11.00-11.20 Pause 11.20-12.50 Gerd Müller 12.50-14.00 Lunch 14.00-15.30 Mark Bedau 15.30-16.00 Pause 16.00-17.00 Roundtable This conference is organized by PHIS and CPNSS. PHIS is a Danish national collaboration on Ph.D-education in the fields of philosophy, history of science and history of ideas. Center for the Philosophy of Nature and Science Studies, is at University of Copenhagen and involves a group of researchers engaged in the interdisciplinary fields of philosophy of science, and science studies. "
"Theoretical High Energy Seminar";"E. Bjerrum-Bohr";"2010-10-07";"14.15";"";"";"Aud D, Blegdamsvej";"Title: Some on-shell methods: Spinors, Vectors and Symmetries, Donal O'Connell, NBIA ";" Donal O'Connell, NBIA Title: Some on-shell methods: Spinors, Vectors and Symmetries "
"Talk by Christine Silberhorn, Universität Paderborn, Angewandte Physik, Integrierte Quantenoptik";"Eugene Polzik";"2010-10-07";"15:15";"";"";"Quantop Lounge";"Quantum state engineering with pulsed light and integrated optics ";" For the generation of quantum states of light parametric downconversion has become an established standard, but the implementation of compact sources for use in larger networks is still challenging. We employ KTP waveguides and ultrafast pump pulses with engineered dispersion properties to generate photon number correlated photonic state in genuine ultrafast single mode pulses. In the low pump power regime this allows the optimized preparation of pure heralded single photons needed with exceptionally high generation efficiencies and very good state preparation fidelities. For higher pump powers the same process can be utilized to implement a very compact genuine ultrafast two-mode squeezer in a single-pass configuration with exceptional brightness featuring significant squeezing values. "
"Talk by Claude Fabre, Universite Pierre et Marie Curie";"Bo Melholt Nielsen";"2010-10-08";"10:15";"";"";"Aud. M";"Quantum limits to the accuracy of optical measurements using Gaussian multimode quantum resources ";" Multimode Gaussian quantum light, which includes multimode squeezed and multipartite quadrature entangled light, is a very general and powerful quantum resource which has already successfully used in quantum information processing and metrology involving continuous variables. It is possible using information theory techniques to determine the ultimate sensitivity in the estimation of any parameter when the information about this parameter is encoded in multimode Gaussian light, irrespective of the exact information extraction protocol used in the estimation. I will show that, for a given set of available quantum resources, the most economical way to maximize the sensitivity is to put the most squeezed state available in a well defined light mode. This implies that it is not possible to take advantage of the existence of squeezed fluctuations in other modes, nor of quantum correlations and entanglement between different modes. I will finally show that it is actually possible to reach this bound by an apropriate homodyne detection scheme, and give some examples of applications. "
"4th Annual Biotechnology Lecture and Awards";"Steen Gammeltoft";"2010-10-08";"13:00";"";"16:00";"Hannover Auditorium, Panum Institute, University of Copenhagen, Blegdamsvej 3B, Copenhagen N";"Hannover Auditorium, Panum Institute, University of Copenhagen, Blegdamsvej 3B, Copenhagen N. ";"Session I: Annual Biotechnology Lecture 13.00 - 13.10 Lars Juhl Jensen, Disease Systems Biology, NNF Centre for Protein Research, University of Copenhagen, Panum Institute: Presentation of 4th Annual Biotechnology Lecture. 13.10 - 14.00 Bernhard Palsson, Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA: The meta-structure of the E. coli genome and its genome-scale transcriptional regulatory network Abstract: Regulation of gene expression is widely considered to be a core issue in biology. Normally such studies have focused on a single gene or a group of genes. Advances in ChIP-chip technology now enable us to study this issue on a genome scale. We have obtained close to a 100 ChIP-chip data sets for E. coli K-12 MG1655 that include; RNAP, the sigma factors, most of the broad acting transcription factors (TFs), and the majority of the nucleoid associated protein (NAPs). In addition we have obtained tiling array data for expression profiling and transcription start site (TSS) data from short read sequencing technology. Degradation start sites (DSS) are obtained by a variation of the TSS protocol. This data enables us to 1) formulate the metastrucure (that is comprised of the functional, structural and operational annotation) of the E. coli genome and 2) to draft the reconstruction of the transcriptional regulatory network (TRN) in E. coli at a genome-scale. 14.00 - 14.30 Coffee break Session II: Annual Biotechnology Awards for Young Researchers 14.30 - 14.40 Steen Gammeltoft, Glostrup Hospital, Denmark: Presentation of 4th Annual Biotechnology Awards for Young Researchers. 14.40 - 15.00 Dimitrios Stamou, Bio-Nanotechnology Laboratory, Dept. Neuroscience and Pharmacology and Nano-Science Center, University of Copenhagen: Lipid-Membrane Biotechnology and Synthetic Biology on the Nanoscale. 15.00 - 15.20 Tina Hummelshøj, Dept. Clinical Immunology, Rigshospitalet: The Ficolins - new defence players of the innate immune system. 15.20 - 15.40 Karl, Agger, BRIC, Biocenter, University of Copenhagen: Erasing the histone methylation mark: Identification and characterization of histone demethylases 15.40 - 16.00 Reception and refreshments Registration on-line: www.biokemi.org Everybody is welcome. Admission is free. Registration is encouraged. Secretariat: Vivian Juhl, Dept. of Clinical Biochemistry, Glostrup Hospital, 2600 Glostrup, Denmark. Tel: 38 63 24 58. vijb@glo.regionh.dk "
"PhD defence by Bo Melholt Nielsen";"Eugene Polzik";"2010-10-08";"14:15";"";"";"Aud. D";"A non-classical light source for light-matter interfaces ";" A non-classical light source for light-matter interfaces The main part is an account of the work done on a non-classical source of light. The non-classical light source described here is based on heralded continuous-wave spontaneous parametric down-conversion, and is shown capable of producing three such non-classical quantum states of light - i.e. squeezed coherent states, single photons and Schrödinger cat states. The light source is motivated for its use as a quantum state resource in fields, such as quantum information, computation and processing. The three optical quantum states are analyzed and shown being of high quality and inherently applicable to atomic quantum memory protocols. The second part is an account of the work done on an optomechanical dielectric membrane. The optomechanical membrane is motivated by its uses in fundamental test of quantum mechanics and by its many prospects of interfacing to optical and atomic quantum systems. The optomechanical membrane system is described and discussed for the purpose of entering into the quantum regime, while the planned implementations of the initial-phase experiment are presented and discussed. Thesis available from: http://dl.dropbox.com/u/4010958/Thesis/201007%20PhD%20thesis.pdf "
"Physics and Mathematics of Random Matrix Theory";"P.H. Damgaard";"2010-10-13";"";"";"";"Aud. A, Blv.";"Niels Bohr International Academy is hosting a workshop on the Physics and Mathematics of Random Matrix Theory ";" The Niels Bohr International Academy is hosting a workshop on the Physics and Mathematics of Random Matrix Theory. More details about the workshop can be found here. "
"PhD Defense by Jakob Jakobsen, DTU- Space";"Aksel Walløe Hansen, NBI";"2010-10-13";"10:00";"";"";"NBI, Rockerfeller Komplekset, Juliane Maries Vej 30, 2. sal A-B, DTU Space, 2100 København Ø";"Kinematic GNSS: Ionospheric variations and characteristicts of Multipath ";" Kinematic GNSS: Ionospheric variations and Characteristics of Multipath by Jakob Jakobsen Teaser/abstract: The variation in the ionosphere and multipath in indoor environemnts are two of the largest factors affecting the GNSS signals. This thesis is focusing on the impact in real time kinematic network positioning services as well as identifying the time varying characteristics of the ionosphere. Furthermore has computer controlled cars on a 27 m. long slot car track been used to characterise the degradation of the GNSS signals under indoor kinematic conditions as well as the impact in the positioning domain. There will be a live demo of the slot car track Supervisors: Carl Christian Tscherning, Per Knudsen, Anna Jensen, Gerard Lachapelle "
"Colloquium by Nikolaj Becker";"Nikolaj Becker";"2010-10-18";"14:15";"";"";"HCØ, Universitetsparken 5, 2100 København ø, Bygning D lokale D317";"Thermodynamic geometry used to optimize optically driven multi-stage processes - with an application to photosynthesis ";"Thermodynamic geometry is used to optimize the electron transport chain of oxygenic photosynthesis. Dividing the series of light and dark reactions into four stages interconnected by three different electron carriers allows usage of a theorem from thermodynamic geometry to compute the least entropy producing way to transfer electrons from water to NADP. This nonspontaneous process is driven by absorption of a number of photons. By viewing the photon uptake as pure energy input, the optimal redox levels of the electron carrier pools are computed. Colloquium by Nikolaj Becker "
"Seminar on Air Quality Forecasting - 1";"CEEH";"2010-10-25";"10:00";"2010-10-25";"11:00";"The Niels Bohr Institute, Aud A, Blegdamsvej 17, Copenhagen";"Development and Application of Global-Through-Urban and Mesoscale WRF/Chem ";" Development and Application of Global-Through-Urban and Mesoscale WRF/Chem Talk by Yang Zhang, Air Quality Forecasting Laboratory, Department of Marine, Earth, and Atmospheric Sciences North Carolina State University, Raleigh, NC, USA Abstract: The climate-air quality feedbacks are important at all scales. Accurately simulating those feedbacks requires fully-coupled meteorology, climate, and chemistry models and presents significant challenges in terms of both scientific understanding and computational demand. China, one of the regions with the largest population and the worst air pollution in the world, provides an ideal testbed for studying such interactions in contrast to the U.S., where emission control strategies have been effectively enforced. In this study, a unified Global-through-Urban Weather Research and Forecasting Model with Chemistry (GU-WRF/Chem) is being developed at North Carolina State University to study air quality-climate interactions. The model is being applied to simulate direct aerosol effects via absorption and scattering and indirect aerosol effects via serving as cloud condensation nuclei (CCN) and affecting cloud droplet number concentration (CDNC) under both current-year and future-year climate and emission scenarios. Nested simulations are conducted over multiple domains such as a global domain at 4˚ (Lat) × 5˚ (Lon), a Trans-Pacific domain covering Asia, Pacific, and North America at 1.0˚ × 1.25˚, the continental U.S. and China at 0.33˚ × 0.42˚, and the eastern U.S. at 0.08˚ × 0.10˚. Model performance evaluation using surface and satellite data is conducted to assess the capability of the model to reproduce meteorological and chemical observations. The important feedbacks of gases and aerosols to simulated boundary layer meteorology, radiation, and cloud/precipitation formation as well as associated seasonalities are studied. The impact of climate change and projected emissions in future years on air quality is examined. Major challenges in simulating climate-air quality interactions will be discussed. Short Biography: Yang Zhang is a Professor in the Department of Marine, Earth, and Atmospheric Sciences at North Carolina State University (NCSU), Raleigh, NC. Her research interests include air pollution modeling and assessment, atmospheric chemistry and transport cloud/aerosol chemistry and microphysics, sensitivity and uncertainty analysis, and interactions among chemistry, meteorology, and climate change. She has led or contributed to the development, application, evaluation, and improvement of several major three-dimensional models on urban, regional, and global scales including STEM III, GChM, MIRAGE, SCICHEM, CMAQ, CMAQ-MADRID, CAMx, MM5, WRF, and mesoscale and global-through-urban WRF/Chem and WRF/Chem-MADRID. The talk by Yang Zhang is the first of two talks in a seminar about air quality forecasting. 10:00 - 11:00 Yang Zhang: Development and Application of Global-Through-Urban and Mesoscale WRF/Chem 11:00 - 11:15 coffee 11:15 - 12:15 Christian Seigneur: Overview of Secondary Organic Aerosol Modeling for Atmospheric Particulate Matter and Recent Developments in Data Assimilation for Air Quality Forecasting "
"Seminar on Air Quality Forecasting - 2";"CEEH";"2010-10-25";"11:15";"2010-10-25";"12:15";"The Niels Bohr Institute, Aud A, Blegdamsvej 17, Copenhagen";"Overview of Secondary Organic Aerosol Modeling for Atmospheric Particulate Matter and Recent Developments in Data Assimilation for Air Quality Forecasting ";" Overview of Secondary Organic Aerosol Modeling for Atmospheric Particulate Matter and Recent Developments in Data Assimilation for Air Quality Forecasting Talk by Christian Seigneur, Cerea, Joint Laboratory École des Ponts ParisTech/EDF R&D, Université Paris-Est Abstract: Fine particulate matter (PM2.5, i.e., those particles with an aerodynamic diameter of less than 2.5 microns) can lead to adverse respiratory and cardio-vascular health effects. PM2.5 includes both primary (i.e., emitted directly in the atmosphere as particles) and secondary (i.e., formed in the atmosphere from condensation of gases) components. The secondary fraction is generally dominant except near sources of primary PM. Furthermore, organic species constitute a significant fraction of secondary PM2.5. It is, therefore, essential to understand the origins of organic PM2.5 to develop efficient emission control strategies of its gaseous precursors. Several approaches are available to model the formation of secondary organic aerosols (SOA). The most commonly used approaches include the fitted-yield approach (also referred to as the two-product Odum approach), the volatility basis-set (VBS) approach, and the hydrophobic/hydrophilic organic (H2O) aerosol approach. The pros and cons of these three approaches will be discussed. Historically, most models have used the fitted-yield approach. Over the past few years, the VBS approach has been increasingly used for applications in North America, whereas the H2O approach has been developed further to be compatible with any gas-phase mechanism and has been incorporated in several European air quality models. Recent work on SOA formation from isoprene will be presented. Examples will be given for regional model simulations and compared to available measurements. Recommendations for further model development and future prospects will be discussed. Recent developments in data assimilation for air quality forecasting conducted at Cerea will also be briefly presented. Short Biography: Christian Seigneur is currently a professor at École des Ponts ParisTech, the top civil and engineering graduate school in France, and the director of its Atmospheric Environment Center, Cerea. He has been an advisor to the U.S. Environmental Protection Agency for the regulation of several atmospheric pollutants including the first PM2.5 regulations and the recent NO2 regulation. His research focuses primarily on atmospheric aerosols and the impact of road traffic on air quality. The talk by Christian Seigneur is the second of two talks in a seminar about air quality forecasting. 10:00 - 11:00 Yang Zhang: Development and Application of Global-Through-Urban and Mesoscale WRF/Chem 11:00 - 11:15 coffee 11:15 - 12:15 Christian Seigneur: Overview of Secondary Organic Aerosol Modeling for Atmospheric Particulate Matter and Recent Developments in Data Assimilation for Air Quality Forecasting "
"Master Thesis defense by Dadi P. Sveinbjörnsson";"Robert Feidenhans'l";"2010-10-25";"14:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, C413";"Metal Borohydrides for Hydrogen Storage and Solid Electrolytes ";" The hydrogen storage properties and the electrical conductivity of LiBH4+Lil mixtures were studied. Using powder diffraction and impedance spectroscopy, it was investigated if the highly conducting, high temperature phase of LiBH4 could be stabilized at room temperature by partical substitution of BH4- by other ions. The main aims were to see if the hydrogen desorption temperature of LiBH4 could be lowered, and to see if the conductivity of LiBH4 could be enhanced at room temperature. The main results are that the high temperature phase of LiBH4 can be stabilized at room temperature by Lil or LiBr addition, and that the LiBH4+Lil mixtures maintain the high conductivity behavior of the high temperature phase of LiBH4 down to room temperature. This could make such mixtures suitable as solid electrolytes in all-solid state batteries. Master Thesis defense by Dadi P. Sveinbjörnsson "
"Atmospheric implications of the geological storage of carbon dioxide";"Centre for Ice and Climate";"2010-10-26";"10:15";"";"";"Room 235, 3rd floor, Juliane Maries Vej 30";"Talk by David M. Etheridge, CSIRO Marine and Atmospheric Research, Aspendale, Australia, Cooperative Research Centre for Greenhouse Gas Technologies and Centre for Ice and Climate, KU ";"Talk by David M. Etheridge, CSIRO Marine and Atmospheric Research, Aspendale, Australia, Cooperative Research Centre for Greenhouse Gas Technologies and Centre for Ice and Climate, KU Abstract: The storage of carbon dioxide in geological formations is being developed as a significant technology to mitigate climate change. CO2 from several types of source would be captured and injected into suitable deep geological formations, rather than being emitted to the atmosphere as presently occurs. The implications for future long term CO2 emissions depend on several factors, including the source of the CO2, the potential leakage if any, and the extra energy required for the process. Leakage to the atmosphere must be kept very low for sustained climate benefit. Monitoring the reservoir and the nearby environment of storage sites to confirm such low leakage will be technically and scientifically challenging. Monitoring the atmosphere will depend on being able to discriminate potential CO2 leaked from storage from the large and variable CO2 background, which will require a suite of atmospheric measurement and modelling techniques. "
"String Study Group";"Charlotte Kristjansen";"2010-10-26";"13:15";"2010-10-26";"14:30";"FB6";"J. Camps (NBI): ""Black Brane Viscosity and the Gregory-Laflamme Instability"" ";"Joan Camps (NBI) presents his recent paper 1003.3636 entitled ""Black Brane Viscosity and the Gregory-Laflamme Instability"" "
"NBA History of Science Seminar";"Niels Bohr Archive";"2010-10-27";"14:15";"";"";"Aud. A, Niels Bohr Institute, Blegdamsvej 17";"Inaccessible Earth: Geomagnetism, In Situ Measurements, Remote Sensing, and Proxy Data, Gregory A. Good ";" Gregory A. Good, Center for History of Physics American Institute of Physics, College Park, U.S.A. Inaccessible Earth: Geomagnetism, In Situ Measurements, Remote Sensing, and Proxy Data More info: here "
"Master thesis defense by Rawa Tanta ";"Jesper Nygård";"2010-10-27";"15:15";"";"";"HCØ, Universitetsparken 5, 2100 Copenhagen, Building D room D203";" Electrical Characterization of Heterostructure Nanowires ";" Heterostructure nanodevices opens a new door for nanoelectronic applications, and fabricating 1D heterostructure nanodevices has been reported where semiconductor nanowires were the perfect candidate for such application my manipulating their components, specially group III-V semiconductor by interchanging either group V or group III elements. Forming heterostructure nanowires by manipulating group V elements has been established by Bjork et al (2002) who managed to produce InAs- InP superlattices. In the Nanolab of Copenhagen University Peter Krogstrup managed to grow epitaxial heterostructure nanowires by interchanging group III elements in III-V semiconductor nanowire producing InAs-GaAs superlattices, GaAs segment in the wire will form a potential barrier inside. The aim of this thesis is to determine this barrier height by applying thermionic emission measurements on the nanowire. This thesis includes the attempts that had been made in order to establish Ohmic contact to the nanowires. Thermionic emission measurements has been done and the potential barrier height has been calculated and found to be around 0.6 eV which is compatible with the estimated value for the bulk material of the same structure. Master thesis defense by Rawa Tanta "
"Master Thesis by Jens Frydenvang";"Kjartan Kinch";"2010-10-28";"13:00";"";"";" Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København 2100, Lokale 071";"Laser-Induced Breakdown Spectroscopy, New approch to obtain an elemental analysis ";" Laser-Induced Brakdown Spectroscopy New approch to obtain an elemental analysis Abstract: Laser-Induced Breakdown Spectroscopy (LIBS) er en analysemetode der kan give grundstofsammensætningen af en given prøve. Teknikken har en række attraktive egenskaber der adskiller denne metode fra andre metoder; bl.a. kræves der meget lidt tid pr. analyse (kun fÃ¥ sekunder), og som den eneste analysemetode kræver LIBS kun at der er ’optisk’ kontakt til prøven – det er derfor muligt at analysere prøver som er flere meter væk. Disse unikke egenskaber har medført at LIBS-teknikken har tiltrukket sig større og større opmærksomhed gennem de sidste Ã¥r, en interesse der bl.a. har udmøntet sig i at LIBS udstyr er med pÃ¥ NASA’s næste Mars rover: Curiosity. LIBS resultaterne har imidlertid vist sig ekstremt afhængige af andre parametre end hvilke grundstoffer prøven bestÃ¥r af; hvorfor det har vist sig meget svært at opnÃ¥ konsistente resultater selv ved gentagne mÃ¥linger pÃ¥ samme materiale. Det er disse problemer som stadig afholder LIBS-teknikken fra at blive alment anerkendt som en troværdig analysemetode – pÃ¥ trods af de mange attraktive egenskaber som LIBS-teknikken tilbyder i forhold til nuværende teknikker. I dette projekt præsenteres en ny tilgang til tolkningen af LIBS-data. Den nye til-gang er en form for hybrid mellem de eksisterende henholdsvis teoretiske og empiriske metoder, og hÃ¥bet er at denne vil være i stand til at opnÃ¥ den ønskede konsistens i fortolkningen af data – samtidig med at alle fordelene ved LIBS-teknikken bibeholdes. Som en del af arbejdet med at definere og verificere denne nye tilgang, er der foretaget LIBS-mÃ¥linger pÃ¥ 22 reference jordprøver fra USGS og NIST, samt pÃ¥ 4 Mars analoge jordprøver. Supervisors: Kjartan Kinch, Morten Bo Madsen, Niels Bohr Institutet; Klaus Mosegaard, DTU; Christian Bender Koch, KU-LIFE "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-10-28";"13:15";"";"";"Auditorium A, Blegdamsvej 17";"Geometric flows and instantons at a Lifshitz point - Ioannis Bakas (U. Patras) ";" Ioannis Bakas (U. Patras) Title: Geometric flows and instantons at a Lifshitz point "
"Master Thesis Defense by Henrik Hasnæs";"Holger Bech Nielsen";"2010-10-29";"13:00";"";"";"Aud 2 HCØ";"Review and simulation of Pregeometric Models ";" Speciale kollokvium in aud 2 HCØ friday 29 october 2010 at 13 am. Review and simulation of Pregeometric Models Wheeler suggested that geometry is not fundamental to physical phenomena and had to be replaced by a discrete model, a 'pregeometry ', in order to reconcile gravity with quantum mechanics. According to Wheeler this pregeometry can only be discovered by studying non-geometric structures. Cellular automata show that simple dynamics can generate physical behavior over larger scales. By simulating discrete dynamics it may be possible to make progress by testing ideas. The results achieved so far are presented with some tentative conclusions. Speaker: Henrik Hasnæs Supervisor: Holger Bech Nielsen "
"NBIA Colloquium";"P.H. Damgaard";"2010-10-29";"2:15 pm";"";"";"Aud. A, Blv.";"Maps and graphs on surfaces - Carsten Thomassen, Technical University of Denmark. ";" Title: Maps and graphs on surfaces Speaker: Carsten Thomassen, Technical University of Denmark. Abstract: p { margin-bottom: 0.21cm; } Graph coloring is an extensively studied subject, partly because of its relation to optimization (time table problems). Graph coloring shows up in other contexts. For example, Lieb’s Square Ice Constant can be expressed in terms of colorings. One of the main sources of inspiration was the 4 Color Problem (now a theorem). In 1890 Heawood considered the analogue for higher surfaces. This problem, known as the Heawood map color theorem, was settled by Ringel and Youngs in 1968. For example, the number of colors needed in the projective plane and the Klein bottle is 6. For the torus it is 7, etc. Although these numbers tend to infinity, there is a 5-color theorem for each surface in the following sense: For every surface S, there exist a finite number of (forbidden) graphs such that an arbitrary graph on S can be 5-colored if and only if it does not contain one of the forbidden graphs as a subgraph. There is no 4-color theorem of this type. In the talk these and related results will be discussed. "
"Talk by Heloisa N. Bordallo";"Kim Lefmann";"2010-11-02";"11:15";"";"";"HCØ, Universitetsparken 5, København Ø, D bygningen lokale 311";"Using Neutrons to Understand the Dynamics of Functional Groups in Crystalline Drugs ";" Understanding structure-properties relation is a central problem in materials science. It is especially important for pharmaceuticals, which are prone to be polymorphic - i.e. the same molecule can crystallize in different 3D-structures. One of the most powerful ways of getting insight on the strength of atomic interactions is to measure the dynamic properties of the system, and neutrons with a 1 Ã wavelength and energy close to 1 kcal/mol are a valuable technique to characterize thermal molecular motions and conformational changes in hydrogen bond systems. Normally dynamical properties are studied at simpler model systems - molecular crystals with selected functional groups - that can mimic important functional groups, such as the acetamide group. For instance, structure and vibrational studies of N-methylacetamide (CH3CONHCH3), a single amide containing methyl groups at both extremities, has been the subject of a numerous investigations. Here I take the approach that relating the dynamics of molecular fragments in the acetamide group to molecular packing and to the properties of the hydrogen bond network in crystalline prescription drugs is a motivating question. During this talk I will present recent results on Paracetamol, Methacetine and Phenacetine, widely used medicaments, obtained using inelastic neutron scattering (INS) carried out using the time-of-flight spectrometers NEAT (BERII, Berlin), IN6 (ILL, Grenoble) and the backscattering instruments IN10 and IN16 (ILL, Grenoble). As I shall discuss, the experimental findings allowed to relate the intermolecular hydrogen bonding response to the dynamical behaviour of various molecular fragments, which justify the ability of the structure to different interactions. Such results are important to control polymorphism, shelf-life, processing properties and bioavailability. Talk by Heloisa N. Bordallo "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-11-02";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"Light-cone gauge superstring theory and dimensional regularisation - Koichi Murakami (Okayama Institute for Quantum Physics) ";" Koichi Murakami (Okayama Institute for Quantum Physics) Title: Light-cone gauge superstring theory and dimensional regularisation Abstract: We propose a dimensional regularization scheme to deal with the divergences caused by colliding supercurrents inserted at the interaction points, in the light-cone gauge NSR closed superstring field theory. In this scheme, we formulate the theory in $d$ dimensional spacetime and define the amplitudes as analytic functions of $d$. We show that by considering $d$ to be largely negative, the divergences of the theory are indeed regularized. In the conformal gauge, this regularized string theory in noncritical $d$ dimensions corresponds to worldsheet theory with nonstandard longitudinal part. We formulate this longitudinal part as an interacting CFT with right value of the Virasoro central charge, so that a nilpotent BRST charge can be constructed with the transverse part and the reparametrization ghosts incorporated. Using this CFT, we show that the tree level amplitudes for the (NS,NS) strings of the light-cone gauge superstring field theory in noncritical dimensions can be recast into a BRST invariant form. We also show that in the limit $d \to 10$ they coincide with the results of the first quantized theory without adding any contact interaction terms to the action. If I have a time at the seminar, I will also discuss the application of our scheme to the Ramond sector and to loop amplitudes. "
"Celebration in honour of I. Novikov's 75th birthday";"P. Naselsky";"2010-11-10";"14:00";"";"";"Auditorium A, Blegdamsvej 17";"On the occasion of I. Novikov's 75th birthday, we will have a series of short talks followed by a reception. ";" On the occasion of I. Novikov's 75th birthday, we will have a series of short talks followed by a reception. Programme: 1) Welcome 2) Talk by A.M. Frejsel 3) Talk by M. Hansen 4) Talk by J. Ambjorn 5) Reception "
"Interim Colloquium by Henning Mikkelsen";"Jens Knude";"2010-11-11";"13:00";"";"";"Juliane Maries Vej 30, lokale 071";"Midtvejs Kollokvium ";" Abstract The Bonnor-Ebert sphere model was initially proposed by Ebert (1955) and Bonnor (1956) in order to describe an isothermal, thermal pressure supported, self gravitating sphere bounded by the external pressure. The gravitational stability of these spheres was shown to depend only on one parameter - ξ0 - defined on the boundary of the sphere. Although very convenient for calculations the Bonnor-Ebert sphere model was initially considered too stylized to represent any real astrophysical phenomenon. In the later years, however, it has been found that the model represents the density profile of isolated starless cores like Bok Globules remarkably well, indicating that it reflects the basic physics of these objects correctly. In the talk the present status of the Bonnor-Ebert sphere model and possible extensions to it will be discussed. Supervisor: Jens Knude "
"Theoretical High Energy Seminar";"Marta Orselli";"2010-11-11";"14:15";"";"";"Auditorium A, Blegdamsvej 17, 2100 Copenhagen";"Holographic Quark-Gluon Plasmas - Francesco Bigazzi (Firenze University and INFN) ";" Francesco Bigazzi (Firenze University and INFN) Title: Holographic Quark-Gluon Plasmas Abstract: I will present a class of analytic supergravity solutions dual to strongly coupled thermal gauge theories coupled to massless fundamental flavors. The solutions include the backreaction of the latter up to second order in the parameter that weighs the internal flavor loops. I will discuss how the fundamental fields a ffect the thermodynamical and hydrodynamical properties of the plasmas as well as their interaction with external probes. "
"NBIA Colloquium";"P. Damgaard";"2010-11-12";"14.15";"";"";"Aud. A, Blv";"Title: Data integration in the era of personal genomics, Søren Brunak (DTU and KU) ";" Title: Data integration in the era of personal genomics Speaker: Søren Brunak (DTU and KU) Abstract: Data integration within biology is a rather old idea, and as a concept it now influences strongly how complex biological mechanisms are understood and disease etiology revealed. Molecular level bioinformatics and systems biology, where properties of genes or networks of genes are revealed, have not been having a large overlap with the medical research communities where results made on the basis of information in electronic patient records, public registries, and from the epidemiological area, are created. By extracting phenotype information from the free­text in such records the talk will show how we can extend the information contained in the structured record data, and use it for producing fine­grained patient stratification and quantify disease co­occurrence and comorbidity. One of the aims is to discover genes which play a role in several, highly different diseases. The talk will discuss the perspectives within data integration which includes the medical informatics area – both in terms of data and the methods which are used to integrate them. "
"AFLYST P.G.A. SYGDOM Master Thesis  by Maria E. Wulff";"Eigil Kaas, NBI";"2010-11-15";"15:00";"";"";" Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København, Lokale 062";"Empirical Correction of Simulated Accumulation over Greenland ";"Emperical Correction of Simulated Accumulation Resumè: For at kunne genskabe og med rimelig nøjagtighed forudsige udviklingen af Grønlands indlandsis benyttes iskappemodeller som er baseret pÃ¥ simuleringer fra klimamodeller. Verifikation af disse klimamodeller er derfor essentielt. I dette studie er den regionale klimamodel, HIRHAM5, forceret med re-analysen ERA-Interim, benyttet til at simulere nedbør og akkumulation over Grønland. Forskelle mellem model simuleringen og mÃ¥linger er efterfølgende undersøgt for at verificere modellens nøjagtighed med henblik pÃ¥ at kunne korrigere simuleringen imod de observerede nedbørs- og akkumulationsmængder. For at danne et korrigeret nedbørskort er pÃ¥lidelige mÃ¥linger nødvendige. MÃ¥linger fra 13 meteorologiske stationer er derfor korrigeret for meteorologiske forstyrrelser, hvorefter disse korrigerede observationer er sammenholdt med ERA-Interim/HIRHAM5 simuleringen. Forholdet mellem den simulerede og observerede gennemsnitlige Ã¥rlige nedbør (PSim/PObs) i de forskellige geografiske omrÃ¥der af Grønland gav her et første indblik i HIRHAM5 simuleringens nøjagtighed. For at udvikle et mere detaljeret geografisk kort over forholdet mellem observationer og HIRHAM5 simuleringen blev analysen herefter udvidet til ogsÃ¥ at omfatte observationer fra 47 iskerner boret forskellige steder pÃ¥ indlandsisen. Akkumulationsværdier for de i alt 60 observationspunkter (13 meteorologiske stationer og 47 iskerner), samt forholdet mellem den simulerede og observerede gennemsnitlige Ã¥rlige akkumulation (AccSim/AccObs) er derved beregnet. For at benytte dette forholdskort til korrektion af HIRHAM5 simuleringen er et egentligt forholdsfelt over hele Grønland dannet. Fire forskellige interpolations metoder er her forsøgt anvendt, hvorefter disse fire forholdsfelter er brugt til korrektion af den simulerede Ã¥rlige gennemsnitsakkumulation (1989-2008) fra ERA-Interim/HIRHAM5 modellen. Fire forskellige korrigerede akkumulationskort er sÃ¥ledes opnÃ¥et, hvorefter det mest nøjagtige er udvalgt til at repræsentere den ""faktiske"" akkumulation over Grønland. Et tilsvarende nedbørskort er efterfølgende udarbejdet. Vejleder: Eigil Kaas, Niels Bohr Institutet "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-11-16";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"Amitabh Virmani (ULB, Brussels): G2(2) Dualities, Black Strings, and Kerr-CFT ";" Amitabh Virmani (ULB, Brussels) Title: G2(2) Dualities, Black Strings, and Kerr-CFT Abstract: In this talk I will discuss the use of the hidden G2(2) symmetry of minimal D=5 supergravity to construct black strings. Using these black strings and the associated dual CFT, I will present a proposal for the microscopic realization of the Kerr-CFT correspondence. "
"String Study Group";"C. Kristjansen";"2010-11-17";"11:15";"2010-11-17";"12:30";"FB6";"H. Shimada (NBIA): Supersymmetrisation of simple embedding of AdS_5 x S^5 into twelve dimensions ";" Hidehiko Shimada (NBIA): Supersymmetrisation of simple embedding of AdS_5 x S^5 into twelve dimensions I will talk about an unpublished work of mine. It is very well known that AdS_5 and S^5 can be both embedded into 6 dimensional flat spaces by using quadratic constraints. I will consider a similar embedding of the superspace associated with AdS_5 x S^5, PSU(2,2|4)/(SO(4,1) x SO(5)), into a representation of PSU(2,2|4) by using quadratic constraints. "
"Theoretical High Energy Seminar";"Marta Orselli";"2010-11-18";"14:15";"";"";"Auditorium A";"title: Stringy instanton calculus and and its application to a D7/D3 system, Igor Pesando (Torino University) ";" Igor Pesando (Torino University) title: Stringy instanton calculus and and its application to a D7/D3 system "
"PhD defense by Torben Haugaard Jensen ";"Robert Feidenhans'l";"2010-11-19";"14:00";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, Aud. 4";"Refraction and scattering based x-ray imaging ";" A number of novel refraction and scattering based x-ray imaging contrast mechanisms and their applications are presented in this thesis. This includes grating based x-ray phase-contrast tomography (PCT) of humane lymph nodes. We demonstrate how PCT can be used to identify metastic deposits in lymph nodes and thus can be used for diagnosis and staging of breast cancer. We also demonstrate food industrial applications of PCT using porcine fat. The method of directional x-ray dark-field imaging is also presented. The method provides nano- and micro-textural information and can be used to probe e.g. the orientation of fibers in a sample. Finally high-resolution small-angle x-ray scattering computed tomography (SAXS-CT) is presented. SAXS-CT is used for imaging of molecular parameters of neuronal myelin sheaths in a brain. The parameters are important for the understanding of a number of neurodegenerative diseases. SAXS-CT is also used for imaging of both functional areas in the brain as well as brain tumor morphology. "
"Master Thesis by Maria Wulff";"Eigil Kaas, NBI";"2010-11-22";"14:00";"";"";"Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København 2100, Lokale 062";"Emperical Correction of Simulated Accumulation over Greenland ";" Empirical Correction of Simulated Accumulation over Greenland Abstract For at kunne genskabe og med rimelig nøjagtighed forudsige udviklingen af Grønlands indlandsis benyttes iskappemodeller som er baseret pÃ¥ simuleringer fra klimamodeller. Verifikation af disse klimamodeller er derfor essentielt. I dette studie er den regionale klimamodel, HIRHAM5, forceret med re-analysen ERA-Interim, benyttet til at simulere nedbør og akkumulation over Grønland. Forskelle mellem model simuleringen og mÃ¥linger er efterfølgende undersøgt for at verificere modellens nøjagtighed med henblik pÃ¥ at kunne korrigere simuleringen imod de observerede nedbørs- og akkumulationsmængder. For at danne et korrigeret nedbørskort er pÃ¥lidelige mÃ¥linger nødvendige. MÃ¥linger fra 13 meteorologiske stationer er derfor korrigeret for meteorologiske forstyrrelser, hvorefter disse korrigerede observationer er sammenholdt med ERA-Interim/HIRHAM5 simuleringen. Forholdet mellem den simulerede og observerede gennemsnitlige Ã¥rlige nedbør (PSim/PObs) i de forskellige geografiske omrÃ¥der af Grønland gav her et første indblik i HIRHAM5 simuleringens nøjagtighed. For at udvikle et mere detaljeret geografisk kort over forholdet mellem observationer og HIRHAM5 simuleringen blev analysen herefter udvidet til ogsÃ¥ at omfatte observationer fra 47 iskerner boret forskellige steder pÃ¥ indlandsisen. Akkumulationsværdier for de i alt 60 observationspunkter (13 meteorologiske stationer og 47 iskerner), samt forholdet mellem den simulerede og observerede gennemsnitlige Ã¥rlige akkumulation (AccSim/AccObs) er derved beregnet. For at benytte dette forholdskort til korrektion af HIRHAM5 simuleringen er et egentligt forholdsfelt over hele Grønland dannet. Fire forskellige interpolations metoder er her forsøgt anvendt, hvorefter disse fire forholdsfelter er brugt til korrektion af den simulerede Ã¥rlige gennemsnitsakkumulation (1989-2008) fra ERA-Interim/HIRHAM5 modellen. Fire forskellige korrigerede akkumulationskort er sÃ¥ledes opnÃ¥et, hvorefter det mest nøjagtige er udvalgt til at repræsentere den ""faktiske"" akkumulation over Grønland. Et tilsvarende nedbørskort er efterfølgende udarbejdet. Læs afhandlingen her (pdf - 25 Mb) >> Vejleder: Eigil Kaas, Niels Bohr Institutet "
"PhD defence by Dmitry V. Khakhulin ";"Robert Feidenhans'l";"2010-11-23";"";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, Aud. 2";"Acoustic Vibrations on the Nanoscale: Time-resolved Optical and X-ray Studies ";" Recent development of pulsed optical and x-ray sources has brought great opportunities for time-resolved investigations on laser radiation induced processes in matter. In particular, available techniques are capable of dynamical studies on coherently excited acoustic phonons in nanostructures on characteristic (sub)picosecond timescales. Combination of purely optical and x-ray based pump-probe techniques allows for deeper understanding of transient thermal and mechanical properties of the materials. The thesis addresses development, optimization and application of tabletop instrumentation for ultrafast optical reflectivity and x-ray diffraction experiments. The x-ray diffraction setup is based on an ultrashort laser driven x-ray diode providing picosecond hard x-ray pulses at kilohertz and megahertz repetition rates. Presented experimental results include detection of laser induced eigen vibrations in metal films and semiconductor nanowires using both the optical and the x-ray probes. Some attention is paid to numerical modeling of such acoustic modes in view of different excitation mechanisms. Finally, optical detection of longitudinal and shear strain pulses propagation in thin films of organic semiconductor is demonstrated by means of picosecond acoustic interferometry. PhD defence by Dmitry V. Khakhulin "
"Theoretical High Energy Seminar";"E. Bjerrum-Bohr";"2010-11-23";"14.15";"";"";"Aud A, Blegdamsvej";"Title: Scattering of Open and Closed Strings, Stephan Stieberger, Max Planck Institute, Munich ";" Stephan Stieberger, Max Planck Institute, Munich Title: Scattering of Open and Closed Strings "
"String Journal Club Seminar";"Konstantinos Zoubos";"2010-11-24";"11:15";"";"";"Fb-6, Blegdamsvej 19";"Jerome Gaillard (Swansea):Generating gravity duals using G-structures ";" Jerome Gaillard (Swansea) Title: Generating gravity duals using G-structures Abstract: In order to find new supergravity solutions, one can use the geometric formalism of G-structures as a guide. Using the example of SU(3), I am going to present how one can use geometry in order to generate solutions, and and include backreacting sources. I will talk about how those new solutions relate to known ones, before finally discussing their field theory duals. "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-11-25";"14:15";"";"";"Auditorium A, Blegdamsvej 17";"CMB Fluctuations and String Compactification Scales, Masao Ninomiya (Okayama Inst. for Quantum Physics/RIKEN) ";" Masao Ninomiya (Okayama Inst. for Quantum Physics/RIKEN) Title: CMB Fluctuations and String Compactification Scales "
"Talk by Nanna B. Karlsson, Centre for Ice and Climate";"Centre for Ice and Climate";"2010-11-26";"13:00";"";"";"Room 235, 2rd floor, Juliane Maries Vej 30";"Radio-echo Sounding of Pine Island Glacier, West Antarctica: Understanding the Past from Observations, Analysis and Modelling of Internal Layering ";" Radio-echo Sounding of Pine Island Glacier, West Antarctica: Understanding the Past from Observations, Analysis and Modelling of Internal Layering Abstract The Pine Island Glacier is one of the largest glaciers in West Antarctica with a profound impact on the stability of the West Antarctic Ice Sheet. During the last 35 years the glacier has experienced welldocumented changes in flux and ice thickness, but it is unknown whether the changes are caused by deglaciation as a response to climate change or simply natural fluctuations. In the southern summer 2004/2005 the British Antarctic Survey and the University of Texas carried out a radio-echo sounding survey of Pine Island Glacier retrieving subglacial topography as well as layers of high reflectivity in the interior of the glacier. This talk presents results of a comprehensive study of the internal layering. Based on layer stratigraphy and comparisons with a 3D ice flow model results indicate that no major spatial changes have taken place in the flow pattern of the glacier, but also that the accumulation pattern and rate are likely to have changed since the beginning of the Holocene. "
"Seminar by Dr. Nicolas Sangouard";"Anders Sørensen";"2010-11-30";"10:00";"";"";"Aud. A";"Solid-state photon pair source with introllable delay based on shaped inhomogeneous broadening ";" After a quick presentation of the last experimental results in the frame of quantum storage, I will present a theoretical proposal of a multimode quantum memory based on spontaneous Raman processes in rare-earth doped solids. "
"Midtvejskollokvium by Majken Ellegaard Christensen";"Jes K. Jørgensen";"2010-11-30";"13:00";"";"";"Juliane Maries Vej 30, lokale 062";"Title: Formation of High-mass Stars ";" Formation of high-mass stars Description: The formation of high-mass stars are today very poorly understood compared to low-mass stars. This is because high-mass stars are rarer and are therefore on average further away, their evolution is faster which makes it difficult to detect their intermediate stages, they are generally found in clusters and they strongly interact with their environment. Today we have two competing theories on the formation of high-mass stars: monolithic collapse and competitive accretion. The major differences in the theories are: do they form alone or in clusters? and do they have accretion disks as low-mass stars do during formation? Also, I will present a new discovery, which strongly favorize one of the two theories. To finish off I will talk about my work on high-mass star formation, which is analyzing the molecular emission from the high-mass star forming region G327.3-0.6. Supervisor: Jes K. Jørgensen, Centre for Star and Planet Formation, Niels Bohr Institute "
"Theoretical High Energy Seminar";"E. Bjerrum-Bohr";"2010-11-30";"14.15";"";"";"Aud A, Blegdamsvej";"D-branes Wrapped on Fuzzy del Pezzo Surfaces, Kazumi Okuyama, Shinshu U. ";" Speaker: Kazumi Okuyama, Shinshu U. Title: D-branes Wrapped on Fuzzy del Pezzo Surfaces "
"What can muons tell us about condensed matter ?";"Kim Lefmann";"2010-12-01";"10:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø Aud.3";"Talk By Christof Niedermayer, Laboratory for Neutron Scattering, Paul Scherrer Institut ";"To a particle physicist a muon is a member of the lepton family, a heavy electron with 1/9 the mass of a proton and a spin of 1/2. Since its discovery in 1937, the muon has played a prominent role for tests of special relativity, weak interactions and quantum electrodynamics. In 1957 Richard Garwin and collaborators discovered that spin-polarized muons injected into materials might be useful to probe internal magnetic fields. This gave birth to the field of μSR, which stands for muon spin rotation, relaxation or resonance. Today, the SR technique is a powerful tool for studying the spatial distribution and temporal fluctuations of internal magnetic fields within solids. µSR gives information that is complementary to that provided by scattering techniques. The extreme sensitivity for the detection of local magnetic fields makes it an invaluable tool for the study of systems with very small, dilute or random ordered moments. Its unique time window for studies of dynamical processes bridges the gap between fluctuation rates probed by NMR and neutron scattering. After an introduction to the technique, some examples of muon spin rotation studies in solid state physics will be presented. Talk by Christof Niedermayer "
"String Journal Club Seminar";"C. Kristjansen";"2010-12-01";"11:15";"2010-12-01";"12:30";"FB6";"Maria J. Rodriguez(AEI, Potsdam),TBA ";"Maria J. Rodriguez (AEI, Potsdam), TBA "
"String Journal Club Seminar";"C. Kristjansen";"2010-12-02";"11:15";"2010-12-02";"12:30";"FB6";"Oscar Varela (AEI, Potsdam)TBA ";"O. Varela (AEI, Potsdam) TBA "
"Specialeforsvar af Jacob Sievers";"";"2010-12-03";"10:00";"";"";"Center for Is og Klima, Rockefeller, 2 sal, lok. 235";"Inference of accumulation surfaces in NW Greenland by consolidation of isochronous radio-echo sounding data and inverse Monte Carlo methods applied on a simple flow model. ";"abstract: Due to the recent increasing interest in global warming and its implications, an understanding of the highly climate-sensitive past patterns of snow accumulation across glaciers and ice sheets such as Greenland, has become essential. The Greenland ice sheet represents a formidable climate archive describing many key factors of past climates. Within the ice sheet internal isochronous layers, constituting layers of past deposition, can be detected by radio-echo sounding techniques. This type of data describes the past flow of the ice sheet and can be directly linked to the accumulation above which feeds the flow. The interpretation of radio-echo sounding data however, is tedious and is therefore typically only carried out for single flightlines, thus only providing insight into two dimensions of an actual three-dimensional problem. During this study 25 isochronous layers, which are dated from their depths at NGRIP, have been analyzed in a large number of interconnected aerial radio-echo sounding datasets across the NW Greenland ice sheet to form 25 large isochronous surfaces. A simple two-dimensional and three-dimensional flow model for the Greenland ice sheet has been developed to infer accumulation rates for a number of past periods down to, and including, 7496 yrs before present day, across the expansive surfaces. To determine the correct past accumulation patterns, an inverse Monte Carlo method, in the form of a combined simulated annealing and Metropolis-Hastings approach, is applied to the simple models. "
"Talk by Malin Kylander, Research Fellow, Dept. of Geological Sciences, Stockholm University";"Centre for Ice and Climate";"2010-12-03";"13:00";"";"";"Room 234, 3rd floor, Juliane Maries Vej 30";"Inorganic Geochemistry and Peatlands as Archives of Dust Deposition ";"By Malin Kylander Department of Geological Sciences, Stockholm University Paleorecords of dust provide a means by which we can examine the response of dust over time under very different climatic conditions. Ombrotrophic peat is hydrologically isolated and therefore, like ice, records atmospheric deposition alone and provides continuous, high-resolution, datable records of climate change. The use of peat for reconstructing dust deposition has been demonstrated, but as yet, not systematically examined. In this presentation the on-going work to test this potential paleo-dust archive is presented. This work is based on a 9000 year old record from Store Mosse in central Sweden. Loss on ignition, in combination with elemental chemistry of the samples, aids in identifying those depths where the observed signal is atmospheric in source only. Humification analyses and bulk density are used as a proxy for surface wetness and allows for the linking of broader climatic changes (precipitation, evaporation, temperature) with fluctuations in dust deposition rates. The inorganic geochemistry provides a means to quantify dust deposition as well as make a first attempt at source tracing of the deposited materials; this is important in terms of reconstructing changes in paleo wind regimes. Past variations in aeolian activity in Scandinavia are relatively unknown. Dune building records from Denmark and elsewhere around Europe show several periods of inland sand invasion and dune building during the Holocene. These are linked to cooler and stormier climates caused by shifts in the North Atlantic Oscillation and/or movement of the polar front. The dust deposition record from Store Mosse is compared with available dune building records and records of storminess from the region in order to make a preliminary assessment of the use of peatlands as paleorecords of dust deposition. "
"NBA History of Science Seminar";"Niels Bohr Archive";"2010-12-06";"14.15";"";"";"Lunch room, Niels Bohr Institute, Blegdamsvej 17";"Ronald E. Doel, Challenging Cornucopian Dreams: M. King Hubbert’s advocacy of peak oil and natural limits ";"Ronald E. DoelDepartment of History, Florida State University Challenging Cornucopian Dreams: M. King Hubbert’s advocacy of peak oil and natural limits Abstract "
"Ph.D. defense by Lars A. Buchhave";"Johannes Andersen";"2010-12-06";"15:15";"";"";"NBI, Blegdamsvej 17, Aud. A.";"Detecting and Characterizing Transiting Extrasolar Planets ";"Detecting and Characterizing Transiting Extrasolar Planets Abstract: We live in an exciting time in astronomy: We are poised to answer some of mankind's fundamental questions, such as: Is the Solar system unique, or are Earth-like planets, where life might be comfortable, common in our galaxy? Can we uncover spectroscopic signatures in exoplanet atmospheres suggesting the existence of life elsewhere in the Universe? Fifteen years ago, no planet outside our Solar system had been discovered. Since then, over 500 exoplanets have been found, the vast majority of which are quite unlike those in our own Solar System and unlike any that had been predicted by theory. Today, we are on the brink of discovering planets and planetary systems similar to our own and determining how frequently Earth-like planets orbit stars in our galaxy. A unique opportunity for characterizing an exoplanet exists when the planet transits its host star and thus dims its light slightly: We can infer the planet's exact mass and radius, its bulk density and chemical composition, its temperature and age, and the dynamics of the system. Further observations even allow the study of their atmospheres. This is the kind of physical information needed to inform the next generation of theories to explain the great diversity of observed exoplanets, and transiting planets are being discovered in great numbers from ground-based surveys and dedicated space missions, such as the European CoRoT and NASA's Kepler mission. The focus of this project is to develop and use efficient spectroscopic techniques for studying transiting exoplanet candidates to confirm their planetary nature and characterize their properties. I have closely collaborated with and am a member of three of the world's premier photometric transit surveys: NASA's Kepler mission and the ground-based the MEarth and HATNet surveys. My work has helped to discover and characterize a significant number of true transiting planets, including one of the first transiting super-Earths, the first multi-transiting planetary system containing a possible planet with a radius 1.6 times that of the Earth, and a number of hot-Jupiter planets with surprising properties. Supervisor: Johannes Andersen Followed by a reception in the DARK Lounge, Rockefeller Komplekset, Juliane Maries Vej 30. "
"Theoretical High Energy Seminar";"Marta Orselli";"2010-12-07";"14:15";"";"";"Aud A, Blegdamsvej 17, 2100 Copenhagen";"Title: Loop calculations in superconformal Chern-Simons, Joe Minahan (Uppsala University ";" Joe Minahan (Uppsala University) Title: Title: Loop calculations in superconformal Chern-Simons "
"Theoretical High Energy Seminar";"E. Bjerrum-Bohr";"2010-12-09";"14.00";"";"";"Aud A, Blegdamsvej";"Semiclassical relations and IR effects in de Sitter and slow-roll space-times, Martin Sloth, CERN ";" Speaker: Martin Sloth, CERN Title: Semiclassical relations and IR effects in de Sitter and slow-roll space-times Abstract: Using simple semiclassical relations it is possible to show that the conventional cosmological correlation functions are affected by significant IR corrections in quasi de Sitter space-times when averaged over very large volumes (in the ""large box""). The IR effects apparently imply a breakdown of perturbation theory in the large box on sufficiently long time scales, for example the time between self-reproduction and reheating in chaotic inflation. An interpretation of the apparent breakdown of the perturbative expansion of gravity will also be discussed "
"Niels Bohr Lecture by Konstantin Novoselov";"";"2010-12-13";"15:15";"";"";"H.C.Ørsted Instituttet, Universitetsparken 5, 2100 København Ø. Aud. 3";"Graphene: Materials in the Flatland, K. S. Novoselov, Nobel Prize Winner 2010 in Physics ";"Graphene: Materials in the Flatland When one writes by a pencil, thin flakes of graphite are left on a surface. Some of them are only one angstrom thick and can be viewed as individual atomic planes cleaved away from the bulk. Konstantin Novoselov, School of Physics and Astronomy, University of Manchester. This strictly two dimensional material called graphene was presumed not to exist in the free state and remained undiscovered until the last year. In fact, there exists a whole class of such two-dimensional crystals. The most amazing things about graphene probably is that its electrons move with little scattering over huge (submicron) distances as if they were completely insensitive to the environment only a couple of angstroms away. Moreover, whereas electronic properties of other materials are commonly described by quasiparticles that obey the Schrödinger equation, electron transport in graphene is different: It is governed by the Dirac equation so that charge carriers in graphene mimic relativistic particles with zero rest mass. The very unusual electronic properties of this material as well as the possibility for it's chemical modification make graphene a promising candidate for future electronic applications. Recent progress in graphene samples production allowed for a dramatic improvement in quality. Thus, mobilities of the order of 106 cm2/Vs can be routinely achieved in mono- and bi-layer graphene samples. This brought an influx of novel phenomena, previously non-observable in this material. The influence of electron-electron interaction become dominant and exhibit itself in spectrum modification, fractional quantum Hall effect, etc. Konstantin Novoselov, School of Physics and Astronomy, University of Manchester "
"Master thesis by Nikolaj Becker";"Bjarne Andresen";"2010-12-14";"10:15";"";"";"HCØ, Universitetsparken 5, 2100 København ø, Aud. 10";"Thermodynamic geometry used to optimize optically driven ";" Thermodynamic geometry is used to optimize the electron transport chain of oxygenic photosynthesis. Dividing the series of light and dark reactions into four stages interconnected by three different electron carriers allows usage of a theorem from thermodynamic geometry to compute the least entropy producing way to transfer electrons from water to NADP. This non-spontaneous process is driven by absorption of a number of photons. By viewing the photon uptake as pure energy input, the optimal redox levels of the electron carrier pools are computed. Master thesis by Nikolaj Becker "
"Theoretical High Energy Seminar";"Konstantinos Zoubos";"2010-12-14";"13:15";"";"";"Auditorium A, Blegdamsvej 17";"Jelle Hartong (Bern): TBA ";" Jelle Hartong (Bern) Title: TBA "
"String Study Group";"C. Kristjansen";"2010-12-15";"11:15";"2010-12-15";"12:30";"Fb6";"C. Meneghelli (MPI, Potsdam), Baxter Q-Operators and Representations of Yangians ";" C. Meneghelli (MPI, Potsdam), Baxter Q-Operators and Representations of Yangians I will present a new approach to the construction of Baxter Q-operators based on their intimate relation with the theory of Yangians. New solutions of the Yang-Baxter equation connected with harmonic oscillator algebra serve as building blocks for other solutions via the standard fusion procedure. This mechanism allows to derive the full hierarchy of operatorial functional equations for all commuting transfer matrices and Q-operators. The method is first applied to sl(n|m) symmetric spin chains with fundamental representation in quantum space but can be generalized to any representation (including non-compact) in quantum space. The present study is motivated by the need of a better understanding of AdS/CFT integrability. "
"Master thesis by Rune Hviid";"Jesper Nygård";"2010-12-15";"13:15";"";"";"HCØ, Universitetsparken 5, 2100 København Ø, Aud. 8";"Hafnium Oxide Upgrades pH Sensing InAs Nanowire FET Devices ";" The primary insulation material in semiconductor is SiO2 made by heat-treatment of Si. This material is becoming obsolete and new oxides with a higher dielectric constant are needed. HfO2 is the most promising replacement due to its low reactivity and low leak currents when interfaced with Si. In this thesis I explore mechanical, chemical and electrical properties of HfO2 when incorporated in microelectronic fabrication of InAs nanowire Lable-Free Bio-FET sensors. I introduce the new material, HfO2, into microelectronic device fabrication and determined the conditions for which lithographic patterns can be defined. HfO2 can be deposited on any surface by a process of Atomic Layer Deposition (ALD) that exposes a surface to separate reactive gasses in a controlled amount of time, thus depositing a single monolayer of HfO2 at a time. Next, I define capacitor devices with HfO2 as the dielectric to determine the relative permittivity and breakthrough voltage of amorphous HfO2. Both values were found to be highly dependant on smoothness of the electrode/oxide interface, and HfO2 here found to grow in islands which might have caused tunneling currents through thin oxides. Due to surface reconstruction of InAs nanowires, the density of electrons is highest at the surface which makes their conductance very sensitive to charges near the surface, and the nanowires easy to contact electrically with UV and E-beam lithographic. I determine the optimal fabrication procedure for making InAs NW FET devices with contact resistance of a few kΩ. Then I incorporated HfO2 into InAs nanowire FET devices as the insulating material for electrode and nanowires to prevented short circuit when the device is under water. This role can not be filled by SiO2 since it is permeably to protons and will cause current leaks to the gate. I used the fabricated devies to measure pH on different aqueous solutions, which appeared as clear reproducible steps in current stabilization within a few seconds. Master thesis by Rune Hviid "
"Master Thesis  by Stefan Jansen";"Klaus Mosegaard";"2010-12-16";"13:00";"";"";" lk. 62,  Niels Bohr Ínstitutet, Juliane Maries Vej 30, 2100 København 2100, ";"Parameter Investigation for Subsurface Tomography with Refraction Seismic Data ";" Parameter Investigation for Subsurface Tomography with Refraction Seimic Data By Stefan Jansen Abstract For planned highway and railway improvements in Norway tomographic images were modelled supplementary to results obtained from a layer based interpretation tool like for example the Generalized Reciprocal Method (GRM). In general good agreements between these methods were achieved, but some inconsistencies led to questions whether the tomographic inversions can be improved. In this master thesis the tomographic inversion tool Rayfract has been examined thoroughly with the aim of determining settings and parameters leading to tomographic images with increased velocity contrast. With the help of synthetic models containing various kinds of anomalies the sensitivity of the tool has been investigated. A thorough parameter investigation on one of these models lead to the determination of six combinations of settings and parameters for obtaining an improved absolute RMS-error and model resemblance. Verification of these combinations with a model resembling one of the profiles from Norway showed unexpected responses. Finally these findings were applied to field data. Over all this work shows that two parameters, Smoothing and wavepath width, are decisive for the quality of all conducted inversions. These parameters are both directly or indirectly linked to smoothing of the result. Even if a fixed recipe for the choice of parameters can not be given, as they are dependent on the topography and subsurface condition of each individual profile, this thesis clearly defines the parameters in focus and how to perform a quick and reliable parameter test for each new situation. Supervisors: Klaus Mosegaard University of Copenhagen, Roger Wisèn, Rambøll Danmark "
"DISCOVERY-HET-Seminar";"E. Bjerrum-Bohr";"2010-12-16";"14.15";"";"";"Aud A, Blegdamsvej";"Quantum fields and expanding Universes, Anders Tranberg, NBIA and DISCOVERY CENTER ";" Speaker: Anders Tranberg, NBIA and DISCOVERY CENTER Title: Quantum fields and expanding Universes Abstract: In the very early Universe, most interesting physics took place during and near various phase transitions: The QCD transition, the Electroweak transition, Inflation, Reheating, SUSY-breaking, GUT breaking. In this context, matter must be described as interacting quantum fields, often out of thermal equilibrium. This requires numerical simulations. I will briefly introduce the main obstacles to simulating fields in expanding backgrounds, and then describe an implementation of truly quantum dynamics based on the real-time Schwinger-Dyson (or Kadanoff-Baym) equation and the 2PI effective action. "
"String Study Group";"C. Kristjansen";"2010-12-20";"13:15";"2010-12-20";"14:30";"FB6";"String study group presentation by K. Larsen ";"K. Larsen (Uppsala & Saclay) will present ongoing work. "