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Calendar of Physics Talks Vienna
| Sub-Poissonian fluctuations by three-body loss in mesoscopic atomic ensembles |
| Speaker: | Shannon Whitlock (University of Amsterdam) |
| Abstract: | The study and control of particle number fluctuations has revealed a rich variety of intriguing quantum phenomena in ultracold quantum gases, such as atom (anti)bunching effects, many-body correlations, squeezing and entanglement. We have realized a novel magnetic lattice atom chip using permanent magnetic films to create a vast two-dimensional array of magnetic microtraps for ultracold atoms. Rapid density-dependent three-body atom loss observed in these tightly confining traps are a robust way to prepare small ensembles comprising tens to hundreds of atoms each. Remarkably, random three-body loss also naturally reduces intrinsic shot-to-shot atom number fluctuations below the Poissonian level, analogous to intensity squeezing in optics. This system is ideal for creating collective excitations via laser excited Rydberg states to engineer interactions between atoms. We have performed first experiments with Rydberg atoms excited on an atom chip and have observed significant effects due to the nearby metallic surface. |
| Date: | Mon, 17.05.2010 |
| Time: | 11:00 |
| Location: | Bibliothek Atominstitut, Stadionallee 2, 1020 Wien |
| Contact: | J. Schmiedmayer |
| Dynamics and Structures of Biomolecular Systems |
| Speaker: | Berufungsvortrag Biophysik: Thorsten Hugel (Department of Physics, IMETUM, CeNS ,CIPSM,NIM, Technische Universität München/D) |
| Abstract: | Biomolecular systems sustain life in any organism. They range from molecular motors moving our muscles to signal transduction pathways telling us that we are happy.
In this talk I will first explain some principles of conformational changes and molecular signalling on the example of the heat shock protein and molecular chaperone Hsp90 [1,2].
In the second part I will focus on the interaction between proteins and surfaces in aqueous environment to understand the molecular origins of adhesion and friction [3,4]. Of special interest is how interfaces or medical implants influence protein structure. This is not only relevant for diseases like Alzheimer’s, but also for the strength of spider silk [5].
Throughout the talk I will explain single molecule techniques to study biomolecular systems in a near native environment like Fluorescence Resonance Energy Transfer (FRET) and Atomic Force Microscopy (AFM).
[1] Mickler et al., NSMB (2009)
[2] Ratzke et al., submitted
[3] Horinek et al., PNAS (2008)
[4] Geisler el al., Small (2009)
[5] Geisler et al., submitted
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| Date: | Mon, 17.05.2010 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Technische Universität Wien, Freihaus Hörsaal 1, Turm C (rote Leitfarbe), 1.u.2. OG, 1040 Wien, Wiedner Hauptstraße 8-10 |
| Contact: | Ao.Univ.Prof. Dr. Herbert Störi |
| Interfacing von Hirn und Halbleiter |
| Speaker: | Peter FROMHERZ (Max-Planck-Institut für Biochemie, München) |
| Abstract: | Im Hinblick auf hybride neuroelektronische Systeme (Neuroprothesen, Neurocomputer) ist die Signalübertragung zwischen Halbleiterchips und Hirn von zentraler Bedeutung. Im Vortrag werden die verschiedenen Ebenen der Wechselwirkung der elektronischen und ionischen Systeme betrachtet, die auf biologischer Seite (Ionenkanäle, Nervenzellen, Hirngewebe) und auf physikalischer Seite (Transistoren/Kondensatoren, Multi-Array-CMOS-Chips) eine Rolle spielen. Auf der Basis dieser Technologie wird über Versuche berichtet, die das Interfacing von neuronalen Netzwerken mit Gedächtnisfunktion (kultivierte Netze und Netze aus dem Hirn) zum Ziel haben. |
| Date: | Mon, 17.05.2010 |
| Time: | 17:30 |
| Location: | Universität Wien, Lise Meitner Hörsaal, Strudlhofg. 4, 1090 Wien |
| Contact: | J. Schmiedmayer |
| Schnell rotierende Bose-Gase: der Effekt von Dirichlet-Randbedingungen |
| Speaker: | Florian Pinsker (Uni Wien) (Fakultät für Physik) |
| Abstract: | im Rahmen des Seminars für Mathematische Physik |
| Date: | Tue, 18.05.2010 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | J. Yngvason |
| Strings and branes in the heart |
| Speaker: | Henri Verschelde (Gent Unviversity) (Fakultät für Physik) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Tue, 18.05.2010 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | R. Bertlmann, H. Neufeld |
| Molecular systems biophysics of the cytoskeleton |
| Speaker: | Berufungsvortrag Biophysik: Thomas Surrey (European Molecular Biology Laboratory (EMBL), Heidelberg/D) |
| Abstract: | The cytoskeleton is a dynamic network of protein filaments present throughout the interior of eukaryotic cells. One class of filaments are microtubules. Their spatial arrangement provides an internal coordinate system for intracellular organization and one of their major roles is to generate a bipolar array, the mitotic spindle, during cell division essential for the segregation of the genetic material to the daughter cells. Crucial for microtubule organization in space are the activities of microtubule-crosslinking proteins. Molecular motors and non-motor microtubule bundlers are of importance. We study how system properties of mixtures of microtubules, motors and bundlers emerge from their collective action. Using in vitro reconstitution approaches in combination with fluorescence microscopy, we address questions of how shape and size of self-organized cytoskeletal structures at the micrometer scale are determined by the biophysical properties of nanometer-sized molecular machines which arrange microtubules in space. |
| Date: | Tue, 18.05.2010 |
| Time: | 16:30 |
| Duration: | 60 min |
| Location: | Technische Universität Wien, Freihaus Hörsaal 6, Turm A (grüne Leitfarbe), 2. OG, 1040 Wien, Wiedner Hauptstraße 8-10 |
| Contact: | Ao.Univ.Prof. Dr. Herbert Störi |
| Nanobiophysics: From Single Molecule Interactions to Cellular Mechanics and Adhesion |
| Speaker: | Berufungsvortrag Biophysik: Robert Ros (Center for Biological Physics, Department of Physics, Arizona State University) |
| Abstract: | Forces and mechanical properties play a central role in many biological processes covering a huge range of length and time scale: from the movement of whole organisms over the adhesion, migration, proliferation of cells, down to the mechanics and interactions of single molecules. Cells are able to sense external forces (mechanosensing), translate these mechanical forces into biochemical signals (mechanotransduction) and react to these signals (mechanoresponse). Little is known about the mechanisms and dynamics of this mechanosignaling, mainly for lack of quantitative methods. Mechanics also plays an important role on the level of single biomolecules. For example, forces act between ligands and receptors, forces induce conformational changes in biomolecules, and the mechanical properties of biomolecules are often related to their function.
A powerful technique to probe mechanical properties involved in biological function is atomic force microscopy (AFM) based force spectroscopy. In my talk I will introduce force spectroscopy in general and present three applications of this technique. The first represents the investigation of a protein-RNA interaction related to posttranscriptional regulation on the single molecule level. Further, I will discuss the possibilities to use AFM in combination with confocal fluorescence microscopy to address mechanical properties of single cells in the field of cancer research. In the third example, force spectroscopy is used to investigate cellular adhesion to fibrinogen-coated surfaces related to blood clotting.
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| Date: | Wed, 19.05.2010 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Technische Universität Wien, Institut für Angewandte Physik, Seminarraum 134, Turm B (gelbe Leitfarbe), 5. OG, 1040 Wien, Wiedner Hauptstraße 8-10 |
| Contact: | Ao.Univ.Prof. Dr. Herbert Störi |
| Well-posedness, linear perturbations and mass conservation for the axisymmetric Einstein equations |
| Speaker: | Prof. Omar Ortiz (Univ.Nacional de Cordoba (Argentina) and Albert Einstein Inst., Germany) (Fakultät für Physik) |
| Abstract: | Vortrag |
| Date: | Thu, 20.05.2010 |
| Time: | 13:30 |
| Duration: | 60 min |
| Location: | Währinger Strasse 17, 1. Stock, Zimmer 118 |
| Contact: | R. Beig |
| Sub-Poissonian fluctuations by three-body loss in mesoscopic atomic ensembles |
| Speaker: | Shannon Whitlock (University of Amsterdam) |
| Abstract: | The study and control of particle number fluctuations has revealed a rich variety of intriguing quantum phenomena in ultracold quantum gases, such as atom (anti)bunching effects, many-body correlations, squeezing and entanglement. We have realized a novel magnetic lattice atom chip using permanent magnetic films to create a vast two-dimensional array of magnetic microtraps for ultracold atoms. Rapid density-dependent three-body atom loss observed in these tightly confining traps are a robust way to prepare small ensembles comprising tens to hundreds of atoms each. Remarkably, random three-body loss also naturally reduces intrinsic shot-to-shot atom number fluctuations below the Poissonian level, analogous to intensity squeezing in optics. This system is ideal for creating collective excitations via laser excited Rydberg states to engineer interactions between atoms. We have performed first experiments with Rydberg atoms excited on an atom chip and have observed significant effects due to the nearby metallic surface. |
| Date: | Thu, 20.05.2010 |
| Time: | 14:00 |
| Location: | TU Wien-Atominstitut, Bibliothek, Stadionallee 2, 1020 Wien |
| Contact: | J. Schmiedmayer |
| Speaker: | Jeffrey Bub, Department of Philosophy and Institute for Physical Science and Technology, University of Maryland, USA (Physics colloquium in honour of O. Univ.-Prof. Dr. DDr.h.c. Anton Zeilinger’s 65th Birthday) |
| Abstract: | Richard Feynman (The Character of Physical Law, 1967; p. 129) famously said that nobody understands quantum mechanics: 'Do not keep saying to yourself, if you can possibly avoid it, "But how can it be like that?" because you will get "down the drain," into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that.' What Einstein called a 'spooky action-at-a-distance' in quantum phenomena was the subject of a debate between Bohr and Einstein, who argued that quantum mechanics was incomplete. I review the debate about interpretation as it has evolved from a question about hidden variables to an issue about the role of information in the foundations of physics.
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| Date: | Thu, 20.05.2010 |
| Time: | 17:00 |
| Duration: | 120 min |
| Location: | Lise-Meitner-Hörsaal Fakultät für Physik, 1. Stock, Boltzmanngasse 5/Strudlhofgasse 4, 1090 Wien |
| Contact: | Daniela Charlesworth |
| From Neutron Research to Quantum Information |
| Speaker: | Helmut Rauch, Atominstitut, TU-Wien, Vienna, Austria (Physics colloquium in honour of O. Univ.-Prof. Dr. DDr.h.c. Anton Zeilinger's 65th Birthday) |
| Abstract: | The TRIGA research reactor of the Austrian Universities was a scientific attraction when Anton Zeilinger started his thesis. New experiments with neutrons become feasible and many young scientists were enthusiastic about these new possibilities. He started a project with polarized neutrons and become interested in the ongoing efforts to understand dynamical diffraction theory and to establish neutron interferometry. The cooperation with Ulrich Bonse in Dortmund and with named scientists around the world and with the newly established Institut Laue-Langevin in Grenoble made this project attractive to him. His interest in quantum theory and any kind of epistemological questions were strong argument to join the interferometer team. The most brilliant contribution he made was in connection with the 4π-symmetry experiment where he had to convince me and other people of the group that this phenomenon can be verified even with unpolarized neutrons. This gave rise to a highly cited publication in 1975. He suggested and contributed also to many other experiments in this field and intensified his activities when he come in contact with Cliff G.Shull the later Nobel laureate. Their experiments concerning single- and double slit diffraction and high resolution perfect crystal experiments are nowadays mentioned in many textbooks. His later career was certainly strongly influenced by these neutron experiments. It will be shown how this early experience influenced his further career and how his contributions influenced the further development of neutron quantum optics. |
| Date: | Thu, 20.05.2010 |
| Time: | 17:00 |
| Duration: | 120 min |
| Location: | Lise-Meitner-Hörsaal, Fakultät für Physik, 1. Stock, Boltzmanngasse 5/Strudlhofgasse 4, 1090 Wien |
| Contact: | Daniela Charlesworth |
| Uniqueness for degenerate Kerr-Newman solutions |
| Speaker: | Luc Nguyen (Univ. Oxford) (Fakultät für Physik) |
| Abstract: | Vortrag |
| Date: | Fri, 21.05.2010 |
| Time: | 13:30 |
| Duration: | 60 min |
| Location: | Währinger Strasse 17, Seminarraum A, 2. Stock |
| Contact: | R. Beig |
| Atoms under the looking glass - precise studies of fundamental symmetries and forces |
| Speaker: | Klaus Jungmann (Kernfysisch Versneller Instituut, University of Groningen) |
| Abstract: | At the Kernfysisch Versneller Instituut in Groningen precision experiments are carried out to search for New Physics beyond the Standard Model. Such experiments exploit most modern techniques in atomic, nuclear and particle physics. The research projects include precision measurements on trapped radioactive ions and atoms. Atomic Parity Violation experiments promise new values for Weinberg angle - the constant which gives the mixing of the weak and electromagnetic force. Studies of Time Reversal symmetry address a scientific question relating to the matter-antimatter asymmetry in the universe. For these measurements new atomic trapping techniques and radioactive beams of highest purity needed to be developed. Such experiments at low energies are complementary in their physics potential to accelerator experiments at the highest today possible energies. |
| Date: | Fri, 21.05.2010 |
| Time: | 15:30 |
| Location: | TU Wien Atominstitut, Hörsaal, Stadionallee 2, 1020 Wien |
| Contact: | H. Abele |
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