1,036 research outputs found
A simple but useful method of screening for mesenteric ischemia secondary to acute aortic dissection
Cosmological Lower Bound on Dark Matter Masses from the Soft Gamma-ray Background
Motivated by a recent detection of 511 keV photons from the center of our
Galaxy, we calculate the spectrum of the soft gamma-ray background of the
redshifted 511 keV photons from cosmological halos. Annihilation of dark matter
particles into electron-positron pairs makes a substantial contribution to the
gamma-ray background. Mass of such dark matter particles must be <~ 100 MeV so
that resulting electron-positron pairs are on-relativistic. On the other hand,
we show that in order for the annihilation not to exceed the observed
background, the dark matter mass needs to be >~ 20 MeV. We include the
contribution from the active galactic nuclei and supernovae. The halo
substructures may increase the lower bound to >~ 60 MeV.Comment: 5 pages, 5 figures; accepted for publication in PRD, Rapid
Communicatio
Stent-grafting for a thoracic aortic aneurysm ruptured into the right pleural cavity
AbstractEur J Vasc Endovasc Surg 25, 185–187 (2003
Vector and Axial Form Factors Applied to Neutrino Quasielastic Scattering
We calculate the quasielastic cross sections for neutrino scattering on
nucleons using up to date fits to the nucleon elastic electromagnetic form
factors GEp, GEn, GMp, GMn, and weak form factors. We show the extraction of Fa
for neutrino experiments. We show how well \minerva, a new approved experiment
at FNAL, can measure Fa. We show the that Fa has a different contribution to
the anti-neutrino cross section, and how the anti-neutrino data can be used to
check Fa extracted from neutrino scattering.Comment: Presented by Howard Budd at NuInt04, Mar. 2004, Laboratori Nazionali
del Gran Sasso - INFN - Assergi, Ital
About the measurements of the hard X-ray background
We analyze uncertainties in the cosmic X-ray background measurements
performed by the INTEGRAL observatory. We find that the most important effect
limiting the accuracy of the measurements is related to the intrinsic
background variation in detectors. Taking into account all of the uncertainties
arising during the measurements we conclude that the X-ray background intensity
obtained in the INTEGRAL observations is compatible with the historic X-ray
background observations performed by the HEAO-1 satellite.Comment: 20 pages, 4 figures, accepted for publication in Astrophysics and
Space Scienc
A High Statistics Search for Electron-Neutrino --> Tau-Neutrino Oscillations
We present new limits on nu_e to nu_tau and nu_e to nu_sterile oscillations
by searching for electron neutrino dissappearance in the high-energy wide-band
CCFR neutrino beam. Sensitivity to nu_tau appearance comes from tau decay modes
in which a large fraction of the energy deposited is electromagnetic. The beam
is composed primarily of muon neutrinos but this analysis uses the 2.3%
electron neutrino component of the beam. Electron neutrino energies range from
30 to 600 GeV and flight lengths vary from 0.9 to 1.4 km. This limit improves
the sensitivity of existing limits and obtains a lowest 90% confidence upper
limit in sin**2(2*alpha) of 9.9 x 10**(-2) at delta-m**2 of 125 eV**2.Comment: submitted to Phys. Rev. D. Rapid Com
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