59,722 research outputs found
Nonperturbative Solution of the Super-Virasoro Constraints
We present the solution of the discrete super-Virasoro constraints to all
orders of the genus expansion. Integrating over the fermionic variables we get
a representation of the partition function in terms of the one-matrix model. We
also obtain the nonperturbative solution of the super-Virasoro constraints in
the double scaling limit but do not find agreement between our flows and the
known supersymmetric extensions of KdV.Comment: 12 pages, CERN-TH.6761/9
Osteoarthritis, entheses, and long bone cross-sectional geometry in the Andes: Usage, history, and future directions.
Akin to approaches encouraged by Verano (1997) in the Andes, and Ortner (2011, 2012) for general paleopathological studies, this article focuses on accurate descriptions and definitions of osteoarthritis, entheses, and long bone cross-sectional geometry. By evaluating these conditions as part of biological responses to abnormal skeletal changes and biomechanical stress, this research discusses each condition's pathogenesis. Further, this article emphasizes a "small data" approach to evaluating these conditions in ancient culturally and biologically related human populations, where the study samples must have good skeletal preservation, where estimates of age and sex need to be included as major factors, and where abnormalities need to be described and evaluated. This article also discusses global clinical and osteological research on ways scholars are currently trying to establish industry-wide methods to evaluate osteoarthritis, entheses, and long bone cross-sectional geometry. Recent studies have focused on rigorous evaluation of methodological techniques, recording protocols, and inter- and intra-observer error problems. Additionally, scholars have focused on physical intensity of movement using biomechanics, evaluated burials of known occupation, and used complex statistical methods to help interpret skeletal changes associated with these conditions. This article also narrows to focus on these conditions within thematic "small data" areas throughout the Andes. This research concludes with describing future directions to understand skeletal changes, such as more multidisciplinary studies between osteologists and pathologists, collaborations with living people to collect CT, x-rays, or computer-aided motion capture, and a stronger focus on how these conditions correlate with intense biomechanical changes in younger individuals
Higher Order Graviton Scattering in M(atrix) Theory
In matrix theory the effective action for graviton-graviton scattering is a
double expansion in the relative velocity and inverse separation. We discuss
the systematics of this expansion and subject matrix theory to a new test. Low
energy supergravity predicts the coefficient of the term, a
two-loop effect, in agreement with explicit matrix model calculation.Comment: 15 pages, 1 epsf figure, LaTeX. Minor change
Renormalization of the electron-phonon interaction: a reformulation of the BCS-gap equation
A recently developed renormalization approach is used to study the
electron-phonon coupling in many-electron systems. By starting from an
Hamiltonian which includes a small gauge symmetry breaking field, we directly
derive a BCS-like equation for the energy gap from the renormalization
approach. The effective electron-electron interaction for Cooper pairs does not
contain any singularities. Furthermore, it is found that phonon-induced
particle-hole excitations only contribute to the attractive electron-electron
interaction if their energy difference is smaller than the phonon energy.Comment: 8 pages, version to appear in Eur. Phys. J.
A Note on Flux Induced Superpotentials in String Theory
Non-vanishing fluxes in M-theory and string theory compactifications induce a
superpotential in the lower dimensional theory. Gukov has conjectured the
explicit form of this superpotential. We check this conjecture for the
heterotic string compactified on a Calabi-Yau three-fold as well as for warped
M-theory compactifications on Spin(7) holonomy manifolds, by performing a
Kaluza-Klein reduction.Comment: 19 pages, no figure
PMNCH Knowledge Summary 23: Human Rights & Accountability
Panel presentation for the Global Maternal Health Conference, held in Tanzania in January 2013, organised by Kate Sabot
Presentation Outline
(1) Overview of PMNCH
(2) Overview of Knowledge Summary Process
(3) KS 23 Highlight
Neutrinos from active black holes, sources of ultra high energy cosmic rays
A correlation between the highest energy Cosmic Rays (above ~ EeV) and the
distribution of active galactic nuclei (AGN) gives rise to a prediction of
neutrino production in the same sources. In this paper, we present a detailed
AGN model, predicting neutrino production near the foot of the jet, where the
photon fields from the disk and synchrotron radiation from the jet itself
create high optical depths for proton-photon interactions. The protons escape
from later shocks where the emission region is optically thin for proton-photon
interactions. Consequently, Cosmic Rays are predicted to come from FR-I
galaxies, independent of the orientation of the source. Neutrinos, on the other
hand, are only observable from sources directing their jet towards Earth, i.e.
flat spectrum radio sources and in particular BL Lac type objects, due to the
strongly boosted neutrino emission.Comment: Accepted for publication in Astroparticle Physics; 30 pages, 8
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