Penn Arts & Sciences

The University of Pennsylvania School of Arts and Sciences forms the foundation of the scholarly excellence that has established Penn as one of the world's leading research universities. We teach students across all 12 Penn schools, and our academic departments span the reach from anthropology and biology to sociology and South Asian studies.

Members of the Penn Arts & Sciences faculty are leaders in creating new knowledge in their disciplines and are engaged in nearly every area of interdisciplinary innovation. They are regularly recognized with academia's highest honors, including membership in prestigious societies like the National Academy of Sciences, the American Association for the Advancement of Science, the American Academy of Arts and Sciences, and the American Philosophical Society, as well as significant prizes such as MacArthur and Guggenheim Fellowships.

The educational experience offered by Penn Arts & Sciences is likewise recognized for its excellence. The School's three educational divisions fulfill different missions, united by a broader commitment to providing our students with an unrivaled education in the liberal arts. The College of Arts and Sciences is the academic home of the majority of Penn undergraduates and provides 60 percent of the courses taken by students in Penn's undergraduate professional schools. The Graduate Division offers doctoral training to over 1,300 candidates in more than 30 graduate programs. And the College of Liberal and Professional Studies provides a range of educational opportunities for lifelong learners and working professionals.

 

 

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  • Publication
    Beyond Conformal Field Theory
    (1990-06-01) Nelson, Philip C
    This is an account of some recent work done with H. S. La [1] [2], based ultimately on the work of Fischler and Susskind [3] and Polchinski [4].
  • Publication
    Mesons and Flavor on the Conifold
    (2007-11-27) Levi, Thomas S.; Ouyang, Peter
    We explore the addition of fundamental matter to the Klebanov-Witten field theory. We add probe D7- branes to the N = 1 theory obtained from placing D3-branes at the tip of the conifold and compute the meson spectrum for the scalar mesons. In the UV limit of massless quarks we find the exact dimensions of the associated operators, which exhibit a simple scaling in the large-charge limit. For the case of massive quarks we compute the spectrum of scalar mesons numerically.
  • Publication
    Introduction to Sigma Model Anomalies, in Symposium on Anomalies, Geometry, and Topology
    (1985-03-01) Nelson, Philip C
    Talk presented at the Symposium on Anomalies, Topology, and Geometry, Argonne National Laboratory, March, 1985.
  • Publication
    Interactions Between Bed Forms: Topography, Turbulence, and Transport
    (2006-06-01) Jerolmack, Douglas J; Mohrig, David
    Results are presented examining the interaction between two sandy bed forms under low–sediment transport conditions in a small laboratory flume. The initial artificially made bed forms were out of equilibrium with the flow field. Temporal evolution of bed forms was monitored using time-lapse photography in order to characterize bed form adjustment to the imposed flow. Velocity measurements were collected using an acoustic Doppler velocimeter to characterize both mean flow and turbulence associated with different bed form geometries. Sandy bed forms all had identical initial geometries; however, the initial distance between bed form crests was varied between experiments. Overall deformation of the bed varied as a function of initial bed form spacing; however, bed forms evolved unpredictably as periods of relatively slow change were punctuated by periods of rapidly changing geometry. Subtle changes in bed form trough geometry were found to have a strong influence on turbulence and therefore sediment transport. Comparison with field studies suggests that the mechanisms described herein are active in natural systems.
  • Publication
    Accuracy of Diffusing-Wave Spectroscopy Theories
    (1995-04-01) Durian, Douglas J
    Random walk computer simulations are reported for the electric field autocorrelation of photons transmitted through multiple-scattering slabs. The results are used as a benchmark for judging the accuracy of competing theories of diffusing-wave spectroscopy (DWS), and also for distinguishing between errors introduced from the approximation of diffusive photon transport and from the continuum approximation that the total square wave-vector transfer of a transmitted photon is proportional to its path length in the material. An important conclusion is that these errors partially cancel, giving accuracies on the order of a few percent for typical experimental situations. Detailed comparisons are made as a function of optical thickness, boundary reflectivity, as well as scattering anisotropy; guidelines are generated for optimizing the analysis of actual DWS data in terms of the dynamics of individual scattering sites.
  • Publication
    Analytic Structure of Two Dimensional Quantum Field Theory
    (1986-08-01) Nelson, Philip C
    Talk presented at the Conference on Mathematical Aspects of String Theory at La Jolla, California in August 1986.
  • Publication
    Sedimentary Bed Evolution as a Mean-Reverting Random Walk: Implications for Tracer Statistics
    (2014-09-16) Martin, Raleigh L; Purohit, Prashant K; Jerolmack, Douglas J
    Sediment tracers are increasingly employed to estimate bed load transport and landscape evolution rates. Tracer trajectories are dominated by periods of immobility (“waiting times”) as they are buried and reexcavated in the stochastically evolving river bed. Here we model bed evolution as a random walk with mean-reverting tendency (Ornstein-Uhlenbeck process) originating from the restoring effect of erosion and deposition. The Ornstein-Uhlenbeck model contains two parameters, a and b, related to the particle feed rate and range of bed elevation fluctuations, respectively. Observations of bed evolution in flume experiments agree with model predictions; in particular, the model reproduces the asymptotic t−1 tail in the tracer waiting time exceedance probability distribution. This waiting time distribution is similar to that inferred for tracers in natural gravel streams and avalanching rice piles, indicating applicability of the Ornstein-Uhlenbeck mean-reverting model to many disordered transport systems with tracer burial and excavation.
  • Publication
    Short GRB and Binary Black Hole Standard Sirens as a Probe of Dark Energy
    (2006-09-18) Dalal, Neal; Holz, Daniel E.; Hughes, Scott A.; Jain, Bhuvnesh
    Observations of the gravitational radiation from well-localized, inspiraling compact-object binaries can measure absolute source distances with high accuracy. When coupled with an independent determination of redshift through an electromagnetic counterpart, these standard sirens can provide an excellent probe of the expansion history of the Universe and the dark energy. Short γ-ray bursts, if produced by merging neutron star binaries, would be standard sirens with known redshifts detectable by ground-based gravitational wave (GW) networks such as Advanced Laser Interferometer Gravitational-wave Observatory (LIGO), Virgo, and Australian International Gravitational Observatory (AIGO). Depending upon the collimation of these GRBs, the measurement of about 10 GW-GRB events (corresponding to about 1 yr of observation with an advanced GW detector network and an all-sky GRB monitor) can measure the Hubble constant h to ~ 2–3%. When combined with measurement of the absolute distance to the last scattering surface of the cosmic microwave background, this determines the dark energy equation of state parameter w to ~9%. Similarly, supermassive binary black hole inspirals will be standard sirens detectable by Laser Interferometer Space Antenna (LISA). Depending upon the precise redshift distribution, ~100 sources could measure w at the ~4% level.
  • Publication
    Extrinsic Curvature, Geometric Optics, and Lamellar Order on Curved Substrates
    (2009-11-18) Kamien, Randall D.; Nelson, David R.; Santangelo, Christian D.; Vitelli, Vincenzo
    When thermal energies are weak, two-dimensional lamellar structures confined on a curved substrate display complex patterns arising from the competition between layer bending and compression in the presence of geometric constraints. We present broad design principles to engineer the geometry of the underlying substrate so that a desired lamellar pattern can be obtained by self-assembly. Two distinct physical effects are identified as key factors that contribute to the interaction between the shape of the underlying surface and the resulting lamellar morphology. The first is a local ordering field for the direction of each individual layer, which tends to minimize its curvature with respect to the three-dimensional embedding. The second is a nonlocal effect controlled by the intrinsic geometry of the surface that forces the normals to the (nearly incompressible) layers to lie on geodesics, leading to caustic formation as in optics. As a result, different surface morphologies with predominantly positive or negative Gaussian curvature can act as converging or diverging lenses, respectively. By combining these ingredients, as one would with different optical elements, complex lamellar morphologies can be obtained. This smectic optometry enables the manipulation of lamellar configurations for the design of materials.
  • Publication
    Multiple – Wavelength Catalogs of the Point Sources in the South Ecliptic Pole Region Detected by Blast
    (2009-01-01) von der Linden, Jens
    The goal of this project is to examine the far - infrared sources in the South Ecliptic Pole region (SEP) observed by the Balloon-Borne Large Aperture Submillimeter Telescope (BLAST). A primary science goal is to understand star formation processes. Most of the sources are assumed to be luminous infrared galaxies (LIRGs), in which high rates of star formation are believed to be occurring. The BLAST experiment mapped the 10 SEP at three wavelengths (250, 350 and 500 μm). To aid future studies of the SEP, three lists of interesting sources were created with an IDL source extraction algorithm. The first list is a catalog of all 5 σ sources and their counterparts. The second list contains sources which have unambiguous counterparts in the three wavelengths. The sources of the third list are likely to be high redshift. Spectral Energy Distributions (SED) were fit to each of the listed sources with an IDL SED fitter. Using the SED, preliminary estimates of luminosity and star formation rates can be made. The combined and unambiguous catalogs can be used to select targets for future observations. The third list will be especially useful for selecting high redshift LIRGs for future observations. Many of the presumed high redshift sources are unrealistically bright. It is possible that they are high redshift sources which are gravitationally lensed and magnified by clusters. The number of bright high redshift sources identified was used to test a recent theoretical model of the abundance of clusters.