Past Events

  • Department Colloquium:"The Maps Inside Your Head"

    David Rittenhouse Laboratory, A8

    Vijay Balasubramanian (UPenn) hosted by: Joe Kroll

    How do our brains make sense of a complex and unpredictable world? In this talk, I will discuss a physicist's approach to the neural topography of information processing in the brain. First I will review the brain's architecture, and how neural circuits map out the sensory and cognitive worlds. Then I will describe how highly complex sensory and cognitive tasks are carried out by the cooperative action of many specialized neurons and circuits, each of which has a simple function. I will illustrate my remarks with one sensory example and one cognitive example.

  • Astro Seminar: "The New Ly-alpha Power Spectrum Measurements and constraints on WDM"

    David Rittenhouse Laboratory, A4

    Vid Irsic (University of Washington)

    With the X-Shooter XQ-100 Legacy survey, 100 QSO measurements at intermediate resolutions were available to measure the Lyman-alpha power spectrum in the similar redshift range to SDSS (z=3 - 4.2), but to smaller scales (k_max ~ 6 h/Mpc). I will present these new results and comment on the data-analysis procedure. In the second part of the talk I will focus on using these new data (along with high-resolution high-redshift data) to put constraints on the cosmological and astrophysical parameters, and to review the constraints on the mass of a WDM particle as a DM candidate.

  • Dissertation Defense: "Understanding the Implications of Neural Population Activity on Behavior"

    David Rittenhouse Laboratory, 3W2

    John Briguglio (UPenn)

  • Dissertation Defense: Toric Elliptic Fibrations Over Hirzebruchs

    David Rittenhouse Laboratory, 3C6

    Prashant Subbarao (UPenn)

  • Experimental Particle Physics: "Search for Supersymmetry in Events with Four or More Leptons at ATLAS "

    David Rittenhouse Laboratory, 4C8

    Matthew Klein (Columbia University)

  • Math-Bio seminar: "Controlling the rate of false discoveries in tandem mass spectrum identifications"

    318 Carolyn Lynch Laboratory

    Uri Keich, University of Sydney

    A typical shotgun proteomics experiment produces thousands of tandem mass spectra, each of which can be tentatively assigned a corresponding peptide by using a database search procedure that looks for a peptide-spectrum match (PSM) that optimizes the score assigned to a matched pair. Some of the resulting PSMs will be correct while others will be false, and we have no way to verify which is which. The statistical problem we face is of controlling the false discovery rate (FDR), or the expected proportion of false PSMs among all reported pairings.

  • High Energy Seminar: "Shaving off Black Hole Soft Hair"

    David Rittenhouse Laboratory, 2N36

    Massimo Porrati (New York University)

    After recalling a definition of a black hole "hair" we explain why the only interesting hairs are those that are also remnants. Next, we will examine a recent proposal by Hawking, Perry and Strominger, who suggest that soft photons and soft gravitons can be regarded as black hole hairs that may be relevant to the black hole information paradox.

  • Where Did Half the Light in the Universe Go?

    Franklin Institute 222 N 20th St, Philadelphia, PA 19103

    Professor Mark Devlin (UPenn)

    Prof. Mark Devlin will be presenting a public talk as part of the Museum’s popular Night Skies program. 

    The evening also includes Planetarium shows and an opportunity to look through the rooftop telescopes.

  • Condensed Matter seminar: "Putting Patterns on Spheres: Pollen Grains and Cholesteric Liquid Crystal Shells"

    David Rittenhouse Laboratory, A4

    Max Lavrentovich, University of Pennsylvania

    Insect egg shells, mite carapaces,  pollen grain surfaces, and many other biological materials exhibit intricate surface patterns including stripes, spikes, pores, and ridges.

  • Math-Bio seminar: "Changes in local chromatin structure during homology search: effects of local contacts on search time"

    318 Carolyn Lynch Laboratory

    Assaf Amitai, M.I.T.

    Double-strand break (DSB) repair by homologous recombination (HR) requires an efficient and timely search for a homologous template. We developed a statistical method of analysis based on single-particle trajectory data which allows us to extract forces acting on chromatin at DSBs. We can differentiate between extrinsic forces from the actin cytoskeleton and intrinsic alterations on the nucleosomal level at the cleaved MAT locus in budding yeast.