Past Events

  • 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.

  • 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.

  • 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

  • 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.

  • *Special Topology Seminar*: "Topological Soft Matter"

    David Rittenhouse Laboratory, A4

    Slobodan Žumer

    We use the term “topological soft matter” for systems with stable defects in the orientational order-parameter field. In nematogenic liquid crystals the effects of confining geometry, chirality, or interplay of both may lead to frustration and consequently to stable or metastable disclinations and solitonic deformations. Recently a lot of attention has been devoted to blue phases and confined & colloidal nematics.

  • Special Astro Seminar: Magneto Is Not A Hero: "The Galactic Magnetic Field and the Formation of Density Structures in the Interstellar Medium as Revealed by Planck"

    David Rittenhouse Laboratory Room 4E19

    Juan Diego Soler (IAS)

    Planck has produced the first all-sky map of the polarized emission from dust at submillimeter wavelengths. Compared with earlier ground-based and balloon-borne observations this survey is an immense step forward in sensitivity, coverage, and statistics.

  • ABO Seminar: Photomedicine: 3 Examples From Bench to Bedside

    Donner Auditorium, Basement, Donner Building, 3400 Spruce Street

    Professor Hubert van den Bergh (Photomedicine group Swiss Federal Institute of Technology (EPFL))

    I will discuss 3 developments from the basics to widespread clinical application, in which light is used for detecting disease, and for treating disease. The first case is the development of an auto-fluorescence bronchoscope used for the early detection of bronchial cancer. The second topic is the development of the drug HEXVIX (CYSVIEW in the US), for the early detection and quantitative removal of bladder cancer.
  • Astro Seminar: "Can We Teach Scientific Critical Thinking to non-Scientists and Scientists Alike? (A Modestly Grandiose Educational Proposal to Save the World, Up for Discussion)

    David Rittenhouse Laboratory, Room A4

    Saul Perlmutter (LBNL)

    There is a body of techniques and practices, a language and culture,
    that is usually implicitly taught by apprenticeship and osmosis to
    graduate students and postdocs. This is the underpinning of an
    approach to the world that is shared by scientists, but not much used
    (or understood) by the rest of society. Can we make these implicit
    concepts explicit, and teach them to all undergraduates, whether or
    not they intend to be scientists? Could this help our society
    address difficult issues such as are raised by the global environment

  • Astronomy Night: "The Fate of the Universe"

    David Rittenhouse Laboratories, and Shoemaker Green 209 S 33rd Street

    Dr. Marisa March, Post-doctoral Researcher (University of Pennsylvania)

    Stargazers of all ages are invited to spend an evening looking up! 

    Members of the Department of Physics and Astronomy will help you explore the night sky through telescopes on Shoemaker Green. Special physics demonstrations and a discussion of the fate of the universe are also on the agenda. Join us for any or all of our free Astronomy Night events!