Past Events

  • Condensed Matter Seminar: "Jamming of non-circular and deformable particles"

    David Rittenhouse Laboratory, A4

    Mark Shattuck (City University of New York)

    We study mechanically stable packings of deformable and rigid 2D circulo-polygons using computer simulations. A 2D circulo-polygon is a particle shape formed by the collection of all points equidistant from the edge of a polygon. It is a generalization of the 2D circulo-cylinder and a circle, which are the collections of all points equidistance from a line and a point, respectively. In our model, the circulo-polygon can be deformable, where the only constraint on the particle is that shape factor, the ratio of the area of the polygon to the square of the perimeter, is fixed.

  • Astro Seminar: "Cosmology with Galaxy Clusters: from Weighing the Giants to LSST"

    Anja von der Linden (Stony Brook)

    Surveys of galaxy clusters provide a sensitive probe of cosmology by measuring the evolution of the halo mass function. However, already current cluster surveys are systematically limited by uncertainties in the relation between cluster mass and observables (e.g. X-ray luminosity, cluster richness, SZ decrement). Cluster weak lensing is the most promising observational method to calibrate the mass scaling to the needed precision but requires the control of systematic errors to a few percent each.

  • HET & HEE Joint Seminar: "Applications of the Average Null Energy Condition"

    Center for Particle Cosmology

    Clay Cordova, (IAS Princeton)

    Local energy conditions are the key hypothesis in many classical results in general relativity.  In quantum theory, these local energy conditions are invalidated due to quantum fluctuations.  Nevertheless a weaker condition, the so-called average null energy condition still holds in quantum field theory. I will explain how this condition constrains the data of conformal field theories such as operator product coefficients and scaling dimensions.

  • Condensed Matter Seminar: "Advanced Electron Microscopy Approaches for Condensed Matter Research"

    David Rittenhouse Laboratory, A4

    Eric Stach (University of Pennsylvania)

    In the next year, the Singh Nanotechnology Center will install two new scanning transmission electron microscopes that will bring Penn’s capabilities in atomic scale materials characterization to a world leading level.  In this seminar, I will describe these capabilities using examples from my own research, from the literature and I will include the latest available results from the instrument manufacturers.  This seminar will be deliberately forward looking and is intended to inform the Penn Condensed Matter community of the full scope of capabilities so that they may pla

  • Advances in Biomedical Optics Seminar: "ROS Explicit Dosimetry for Photodynamic Therapy"

    CMROI Conference Room, B1 Stellar Chance Laboratories, 440 Curie Blvd

    Timothy Zhu (HUP)

    (Pizza will be served at 11:45 am)

  • Math-Bio seminar: "Decoding of pairwise coalescent times and detection of recent adaptation in biobank-scale SNP array data sets"

    318 Carolyn Lynch Laboratory

    Pier Francesco Palamara (Harvard School of Public Health)

    Coalescent hidden Markov models (HMM) such as the pairwise sequentially Markovian coalescent (PSMC, Li and Durbin, 2010) enable estimating the locus-specific posterior distribution of the time to most recent common ancestor (TMRCA) of a pair of haploid chromosomes when high-coverage sequencing data is available. I will present the “ascertained sequentially Markovian coalescent” (ASMC), a coalescent HMM that can be used to accurately estimate locus-specific TMRCA probabilities in widely available SNP array data.

  • Condensed Matter Seminar: "Geometry, frustration and force production in bacterial biopolymers"

    David Rittenhouse Laboratory, A4

    Ajay Gopinathan (University of California, Merced)

    Filamentous biopolymers in bacteria are involved in a variety of critical processes including templating cell growth, segregating genetic material and force production during motility and cell division. In this talk, I will discuss how a few of these systems translate biopolymer structure at multiple scales into physical function. At the molecular scale, the filamentous bacterial protein FtsZ converts chemical energy into mechanical constriction during cell division, but without the aid of any motor proteins.

  • Math-Bio seminar: "Mutations, genetic identity, and data granularity"

    318 Carolyn Lynch Laboratory

    Jun Li (University of Michigan)

    I will talk about two studies where new insights are gained after we work on a different level of data granularity. First, in collaboration with Sebastian Zoellner we analyzed ~36 million extremely rare variants (defined as singletons in ~4,000 individuals) uniformly ascertained in an as yet unpublished whole-genome sequencing dataset. Our goal is to estimate mutation rate variation across the genome, and to identify genomic and sequence-based predictors of such variation.

  • High Energy Seminar: "The Re-emergance of Spontaneously Broken Space-time Symmetries without Goldstones or Inverse Higgs"

    DRL 2N36

    Ira Rothstein (Carnegie Mellon)

    In this talk I will discuss how broken space-time symmetries can emerge in the IR after being spontaneously broken in the UV, even though there may be no Goldstone bosons. Given that there has been a large body of work on trying to get space-time symmetry (e.g. Lorentz) to be emergent in the IR via an RG attractive basin, this may seem like a very surprising and non-generic result.

  • Condensed Matter Seminar: "Invisibility, polarized light, and the eyes of giant squid: three tales of biological optics from the deep sea"

    David Rittenhouse Laboratory, A4

    Sonke Johnsen, Duke University