1. Colloquium: Viscosity, Quark Gluon Plasma, and String Theory

    01:08:21

    from UK College of Arts & Sciences / Added

    55 Plays / / 0 Comments

    Viscosity, quark gluon plasma, and string theory Viscosity is a very old concept which was introduced to physics by Navier in the 19th century. However, in strongly coupled systems, viscosity is difficult to compute from first principle. In this talk I will describe some recent surprising developments in string theory which allow one to compute the viscosity for a class of strongly interacting quantum fluids not too dissimilar to the quark gluon plasma. I will describe efforts to measure the viscosity and other physical properties of the quark gluon plasma created in relativistic heavy ion collisions.

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    • Your textbook is still wrong about the Milky Way galaxy

      59:49

      from UK College of Arts & Sciences / Added

      54 Plays / / 0 Comments

      Dr. Heidi Newberg Rensselaer Polytechnic Institute Fifteen years ago, we modeled the distribution of stars in the Milky Way using three components: an exponential disk, a power law spheroid, and a bulge. Then, we discovered the distribution of stars in the spheroid was lumpy due to the accretion and tidal disruption of dwarf galaxies that ventured too close the the Galactic center. We now wonder whether the Milky Way has a classical bulge at all; likely the bulge-like feature we see is instead due to the Galactic bar. And most recently, we are discovering large scale departures from the standard exponential disk. New discoveries point to variations in the expected bulk velocities of stars in the Galactic disk, and oscillations in the spatial densities of disk stars. Some believe these observations point to a wave response to the passing of dwarf galaxies (or dark matter lumps) through the Milky Way's disk. These waves may also explain the observed rings of stars, 15-25 kpc from the Galactic center, which is farther out than we originally believed the disk to extend.

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      • Controlled Magnetic Reversal and Emergent Metamagnetism in Permalloy Films Patterned into Artificial Quasicrystals

        01:11:31

        from UK College of Arts & Sciences / Added

        54 Plays / / 0 Comments

        Dr. Lance Delong University of Kentucky Ferromagnetic (FM) thin films patterned into periodic lattices of nanoscale holes or dots are candidated for UHD data storage media, an drelated wire network patterns are of fundamental interest as examples of controlled phase transitions in "artificial spin ice". Our recent Physical Review Letter reported an experimental study of the static and dynamic magnetic properties of FM permalloy thin films patterned as Penrose P2 (quasicrystal) tilings that exhibit long-range order, but aperiodic translational symmetry. Our DC magnetization and ferromagnetic resonance data constitute, we believe, the first experimental study of th espin wave dynamics of an artificial FM quasicrystalline thin film. Ground-breaking efforts were required to both pattern and deposit the sample film materials, and to execute large-scale numerical simulations of their static and dynamic behavior. This work demonstrates a new method for controlling the evolution of FM domain walls and spin wave spectra in magnetic media, in spite of a lack of periodic symmetry in an artificial quasicrystalline pattern. Simulations reveal a remarkably controlled sequence of reversals of individual film segments located on sublattices of the quasicrystal pattern, which may signal the occurence of true metamagnetic phase transitions in larger-area samples. These results directly imply FM films patterned as Penrose P2 tilings constitute a novel class of magnonic crystals whose magnon frequency dispersion and physical properties were heretofore unknown.

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        • William Cottrell

          15:29

          from UK College of Arts & Sciences / Added

          52 Plays / / 0 Comments

          William Cottrell presenting at Great Lakes String 2013

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          • Arkady Tseytlin

            28:26

            from UK College of Arts & Sciences / Added

            52 Plays / / 0 Comments

            Arkady Tseytlin presenting at Great Lakes String 2013

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            • Arnab Kundu

              27:45

              from UK College of Arts & Sciences / Added

              49 Plays / / 0 Comments

              Arnab Kundu presenting at Great Lakes Strings 2013.

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              • Colloquium: New Dialogues: Entanglement, Holography & Renormalization

                01:15:12

                from UK College of Arts & Sciences / Added

                48 Plays / / 0 Comments

                In science, we often see new advances and deep insights emerging from the collision or intersection of what appeared to be separate research areas. The theme of my colloquium will be an ongoing collision between the three ideas listed in my title which has been generating interesting new insights into a variety of fields, eg, condensed matter physics, quantum field theory and even quantum gravity. I will give an introduction to each of these three ideas separately and then discuss the intersections that have been generating new insights in recent years. Speaker/Presenter: Robert Myers, Perimeter Institute for Theoretical Physics

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                • Rapid Arctic warming and extreme weather events in mid-latitudes: Are they connected?

                  50:14

                  from UK College of Arts & Sciences / Added

                  48 Plays / / 0 Comments

                  Dr. Jennifer Francis Rutgers University In this presentation, I will discuss the hypothesis proposed by Francis and Vavrus (2012) that links rapid Arctic warming (so-called Arctic amplification) to changes in the large-scale atmospheric circulation in the northern hemisphere that favors more persistent weather patterns and a higher likelihood of extreme weather events such as droughts, cold spells, flooding, heavy snows, and heat waves. This hypothesis has been a topic of considerable controversy in recent months, particularly regarding its relationship to the unusual weather conditions that persisted in the winter of 2013/2014. I will discuss various aspects of this linkage, what we know and don't know, and present new related research.

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                  • Peer Observation at the University of St Andrews

                    09:20

                    from University of St Andrews / Added

                    45 Plays / / 0 Comments

                    Bruce Sinclair, Director of Teaching in the School of Physics and Astronomy at the University of St Andrews, gives an overview of how Peer Observation is used in his School. Also lecturers provide their feedback on how peer observation has helped them in improving their teaching methods.

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                    • Peter Ouyang

                      26:26

                      from UK College of Arts & Sciences / Added

                      45 Plays / / 0 Comments

                      Peter Ouyang presenting at Great Lakes String 2013

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