Past Events

  • Astro Seminar: "The Local Universe as a Cosmological Lens "

    DRL A6

    Jonathan Hargis (Haverford)

    The local universe serves as a lens through which we can understand the formation of galaxies in a dark energy + cold dark matter(LCDM) context.  Numerical simulations suggest that galaxies grow hierarchically; that is, from the continuous build-up and tidal destruction of dwarf galaxies and globular clusters.  The discovery of numerous satellite dwarf galaxies and tidal stellar streams in the halo of the Milky Way and Andromeda generally support this picture.  However, detailed observations reveal tensions with LCDM and uncertainties in galaxy formation theory on small scale

  • Math-Bio Seminar: "momi: A new method for inferring demography and computing the multipopulation sample frequency spectrum"

    318 Carolyn Lynch Lab

    John A. Kamm, UC Berkeley

    The sample frequency spectrum (SFS) describes the distribution of allele counts at segregating sites, and is a useful statistic for both summarizing genetic data and inferring biological parameters. SFS-based inference proceeds by comparing observed and expected values of the SFS, but computing the expectations is computationally challenging when there are multiple populations related by a complex demographic history.

  • Physics Department Colloquium: "Fluid 'Ratchets' and Biological Locomotion"

    DRL A8

    Jun Zhang (NYU-Courant Institute)

    In this talk, I will discuss a few laboratory experiments that were inspired from examples of biological locomotion. There, solid structures were forced to interact with their surrounding fluid. These structures, or dynamic boundaries, interact with fluid in asymmetric fashions - either because of their anisotropic geometry or by the spontaneous breaking of symmetry in their response to the fluid. When subject to reciprocal forcing, the coupled systems behave in ways that can be described as 'fluid ratchets'.

  • High Energy Theory Seminar: “Thriving From the Vacuum”

    DRL 2N36

    Claudia de Rham (Case University)

    Theories of modified gravity in the infrared usually come hand in hand with additional degrees of freedom which couple to matter at gravitational strength and carry a low strong-coupling scale. By including non-trivial effects from the vacuum I will show how the strong-coupling scale can be raised while keeping the theory fundamentally Lorentz-invariant. This can lead to new features and may alleviate the need for a screening mechanism.

  • Dissertation Defense: "On Abelian and Discrete Symmetries in F-Theory"

    David Rittenhouse Laboratory, 3C6

    Hernan Piragua

  • Condensed Matter Seminar: "The Granular Physics of (Real) Landscapes"

    David Rittenhouse Laboratory, A4

    Doug Jerolmack (University of Pennsylvania)

    The Earth's surface is a granular-fluid interface, shaped by the feedbacks among water/air flow, topography and particle transport. A bewildering array of patterns arise due to the unstable nature of a sheared, granular free-surface; witness dunes, river networks and barrier islands, for example. For almost a century, research on understanding landscape patterns and predicting rates of sediment transport has focused on developing an ever-more detailed description of the turbulent fluid; the coupling to particle motion is often an afterthought.

  • Astro Seminar: "Early Weak Lensing Results from the Dark Energy Survey"

    DRL A6

    Mike Jarvis (UPenn)

    I will present some of the recent results from the weak lensing analysis of the Dark Energy Survey (DES) science verification data. The science verification (SV) data used the same telescope and camera as the full DES is using, but the data were taken the year prior to the start of the DES.  I will present some of the suite of null tests we used to look for systematic errors in the shear values, showing that the shear catalogs are reliable enough to use for science.  Then I will show some science results from these data including mass maps, cosmology constraints, and troug

  • Welcome Incoming Students

    DRL, Graduate Student Lounge, 3E9

  • Condensed Matter Seminar: "Bending Rules in Graphene Kirigami"

    David Rittenhouse Laboratory, A4

    Gene Mele (University of Pennsylvania)

    The three dimensional shapes of graphene sheets produced by nanoscale cut-and--join kirigami are studied by combining large-scale atomistic modelling with continuum elastic theory. Lattice segments are selectively removed from a flat graphene sheet and the structure is allowed to close and reconstruct by relaxing in the third dimension. The surface relaxation is limited by a nonzero bending modulus which produces a smoothly modulated landscape instead of the ridge-and-plateau motif found in macroscopic lattice kirigami.

  • Linkedin Picture Tour

    3601 Walnut Street Penn Bookstore, 2nd Floor

    Come by to get your free Professional Headshot taken by Linkedin reps!