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Calendar of Physics Talks Vienna
| Recent developments in non-smooth spacetime geometry (Vienna Theory Lunch Seminar) |
| Speaker: | Argam Ohanyan (University Vienna) |
| Abstract: | In Einstein's theory of General Relativity, nonsmooth phenomena naturally arise, e.g. in questions regarding the extendibility of spacetimes, geodesic singularities, or cosmic censorship. Recently, a new approach to spacetime geometry has gained significant popularity, i.e. the theory of Lorentzian length spaces. It is a new way to describe non-smooth spacetimes, and is very promising to deliver great insights, given the success of similar approaches in positive definite geometry (Alexandrov spaces, metric measure geometry, etc.). In this talk, we will introduce some of the basic notions in this theory and discuss recent progress.
[[part of the "Vienna Theory Lunch Seminar, see https://lunch-seminar.univie.ac.at ]] |
| Date: | Tue, 23.04.2024 |
| Time: | 12:30 |
| Duration: | 75 min |
| Location: | University of Vienna: Boltzmanngasse 5, 5th floor, Schrödinger Lecture Hall |
| Contact: | Florian Lindenbauer |
| Molecular mechanotransduction in extra- and intracellular fibrous biomaterials |
| Speaker: | Sapun Parekh (Department of Biomedical Engineering, University of Texas at Austin) |
| Abstract: | Many proteins, particularly those in fibrous extracellular and intracellular structures participate in load bearing and mechanotransduction â the process of converting mechanical signals into biochemical action, in the body. Studies have shown that cell and tissue mechanics strongly influence cell behaviors, and recent work has highlighted the role of fibrous nature of these networks in mechanotransduction. What if the proteins that compose the extracellular matrix or the intracellular cytoskeleton are themselves mechanotransducers? In this talk, I will present our work over the last years using in situ advanced microscopy to quantify protein structure in fibrous protein biomaterials in situ under different mechanical loads. We use label-fee molecular microscopy and Förster resonance energy transfer microscopy to measure protein structure in fibrin ECM and vimentin networks. Our results |
| Date: | Tue, 23.04.2024 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Yellow Tower âBâ, 5th floor, SEM.R. DB gelb 05 B |
| Contact: | Prof. Markus Valtiner |
| Inclusive semileptonic B-meson decays and CKM matrix determinations: challenges and theoretical framework(s) |
| Speaker: | Bernat Capdevila (University of Cambridge) |
| Abstract: | The CKM matrix is a key ingredient in the study of CP violation and in New Physics searches within the flavour sector. Therefore, precise determinations of its matrix elements are of utmost importance. |Vub| and |Vcb| can be extracted from both exclusive semileptonic b â> u and b â> c decays and the inclusive channels B â> Xu l nu and B â> Xc l nu. Exclusive and inclusive determinations of these matrix elements have been in tension for a long time, with even different theoretical frameworks not agreeing well with one another. In this seminar, I am going to review some of the techniques employed in the study of inclusive semileptonic B-meson decays and present the results of our latest inclusive determination of |Vcb|. Then, I will discuss the challenges one needs to face in order to obtain a solid description for B â> Xu l nu and some of the solutions proposed. Finally, I will present th |
| Date: | Tue, 23.04.2024 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-Hoersaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Broggio |
| Static 3+1 vacuum black holes that cannot be put into stationary rotation |
| Speaker: | Martin Reiris (Montevideo) |
| Abstract: | In this talk I will show that there are vacuum static 3+1 black
hole solutions, metrically complete but non-standard spatial topology,
that cannot be put into stationary rotation. That is, there are no
non-static stationary metrics close to them. To our knowledge, this is
the first result of this kind in the literature. This is joint work
with Javier Peraza. |
| Date: | Wed, 24.04.2024 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Per zoom |
| Contact: | P. Chrusciel |
| The emergence of the 2nd law of thermodynamics in isolated quantum systems |
| Speaker: | Maximilian Lock (TU Wien, Atominstitut) |
| Abstract: | According to the second law of thermodynamics, the entropy of an isolated system increases over time. Isolated quantum systems, however, evolve unitarily, and therefore the von Neumann entropy is constant. While it is known that certain observables appear to equilibrate (on average) in an isolated quantum system, the question remains open: in what sense does the entropy of an isolated quantum system increase over time?
The conflict between reversible microscopic, and irreversible macroscopic behaviour in classical systems (the so-called Loschmidt paradox) has been solved using notions of coarse-graining, and an interpretation of thermodynamic laws as averages. We build upon the theory of equilibration-on-average in isolated quantum systems to investigate entropies that are defined with respect to observables and recover a variant of the second law -- the entropy (relative to an equilibra |
| Date: | Wed, 24.04.2024 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Maximilian Prüfer |
| Non-holomorphic Eisenstein Series and Quadratic Forms in Holography |
| Speaker: | Abhiram Kidambi (Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany) |
| Abstract: | Non-holomorphic Eisenstein Series are one of the simplest examples of automorphic forms (generalisations of periodic functions with some nice symmetry properties) which contain a lot of spectral and arithmetic information. In mathematics, they provide insight into important problems such as the theory of zeta functions, the Langlands program. In physics, they arise in a variety of settings in string theory (scattering amplitudes, holography of SL(2,Z) orbits of BTZ black holes) and quantum chaotic systems.
In this talk, I will go over how Eisenstein series for genus 1 surfaces series arise from normed vector spaces (Z modules or lattices) in string theory, and how they encode information of both partition functions in holography and manifold invariants of the solid torus which is of interest in holography. |
| Date: | Thu, 25.04.2024 |
| Time: | 15:00 |
| Duration: | 60 min |
| Location: | TU Wien, Freihaus, Seminar room on the 10th floor |
| Contact: | Daniel Grumiller, Iva Lovrekovic |
| Free electron spectroscopy seen through the prism of quantum optics |
| Speaker: | Hugo Lourenço-Martins (CEMES Toulouse) |
| Abstract: | Photon Induced Near-field Electron Microscopy (PINEM) denotes the modulations of free electrons by a sample â typically an optical cavity â pumped by a laser source. This effect has been theoretically predicted and experimentally demonstrated in an ultrafast transmission electron microscope (UTEM) more than a decade ago [1,2]. Following these seminal developments, PINEM has been used to reconstruct the temporal dynamics of nano-optical systems with an attosecond temporal resolution [3].
Due to recent experimental developments in integrated photonics [4,5], the problem of PINEM in the low occupation regime â i.e. when the cavity is populated by a weak number of photons - has drawn an increasing theoretical interest. Indeed, in this situation, the classical description of the electromagnetic field falls short to describe the electron-cavity interaction, and a full quantum description beco |
| Date: | Fri, 26.04.2024 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Philipp Haslinger |
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