5,428 research outputs found
A Probabilistic Approach to Classifying Supernovae Using Photometric Information
This paper presents a novel method for determining the probability that a
supernova candidate belongs to a known supernova type (such as Ia, Ibc, IIL,
\emph{etc.}), using its photometric information alone. It is validated with
Monte Carlo, and both space- and ground- based data. We examine the application
of the method to well-sampled as well as poorly sampled supernova light curves
and investigate to what extent the best currently available supernova models
can be used for typing supernova candidates. Central to the method is the
assumption that a supernova candidate belongs to a group of objects that can be
modeled; we therefore discuss possible ways of removing anomalous or less well
understood events from the sample. This method is particularly advantageous for
analyses where the purity of the supernova sample is of the essence, or for
those where it is important to know the number of the supernova candidates of a
certain type (\emph{e.g.}, in supernova rate studies).Comment: Version accepted for publication in Astrophysical Journa
Aerospace applications of high temperature superconductivity
Space application of high temperature superconducting (HTS) materials may occur before most terrestrial applications because of the passive cooling possibilities in space and because of the economic feasibility of introducing an expensive new technology which has a significant system benefit in space. NASA Lewis Research Center has an ongoing program to develop space technology capitalizing on the potential benefit of HTS materials. The applications being pursued include space communications, power and propulsion systems, and magnetic bearings. In addition, NASA Lewis is pursuing materials research to improve the performance of HTS materials for space applications
The extraordinary mid-infrared spectral properties of FeLoBAL Quasars
We present mid-infrared spectra of six FeLoBAL QSOs at 1<z<1.8, taken with
the Spitzer space telescope. The spectra span a range of shapes, from hot dust
dominated AGN with silicate emission at 9.7 microns, to moderately obscured
starbursts with strong Polycyclic Aromatic Hydrocarbon (PAH) emission. The
spectrum of one object, SDSS 1214-0001, shows the most prominent PAHs yet seen
in any QSO at any redshift, implying that the starburst dominates the mid-IR
emission with an associated star formation rate of order 2700 solar masses per
year. With the caveats that our sample is small and not robustly selected, we
combine our mid-IR spectral diagnostics with previous observations to propose
that FeLoBAL QSOs are at least largely comprised of systems in which (a) a
merger driven starburst is ending, (b) a luminous AGN is in the last stages of
burning through its surrounding dust, and (c) which we may be viewing over a
restricted line of sight range.Comment: ApJ, accepte
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Cadaveric simulation for improving surgical training in dermatology.
Simulation models are rapidly changing medical education, especially the training of dermatology residents. Various models are available, including cadaveric simulations. Our study evaluates the impact of a cadaveric simulation on the training of dermatology residents. Over a period of three years, cadaveric simulation was shown to increase the surgical knowledge of residents. Residents were more confident in their knowledge of surgical anatomy and also surgical skills. Cadaveric simulation may offer a positive impact on resident training in dermatology
Calculation of High Energy Neutrino-Nucleon Cross Sections and Uncertainties Using the MSTW Parton Distribution Functions and Implications for Future Experiments
We present a new calculation of the cross sections for charged current (CC)
and neutral current (NC) and interactions in the neutrino
energy range GeV using the most recent MSTW parton
distribution functions (PDFs), MSTW 2008. We also present the associated
uncertainties propagated from the PDFs, as well as parametrizations of the
cross section central values, their uncertainty bounds, and the inelasticity
distributions for ease of use in Monte Carlo simulations. For the latter we
only provide parametrizations for energies above GeV. Finally, we assess
the feasibility of future neutrino experiments to constrain the cross
section in the ultra-high energy (UHE) regime using a technique that is
independent of the flux spectrum of incident neutrinos. A significant deviation
from the predicted Standard Model cross sections could be an indication of new
physics, such as extra space-time dimensions, and we present expected
constraints on such models as a function of the number of events observed in a
future subterranean neutrino detector.Comment: 20 pages, 13 figures, 5 tables, published in Phys.Rev.D. This version
fixes a typo in Equation 16 of the publication. Also since version v1, the
following changes are in v2 and also in the published version: tables with cs
values, parametrization of the y distribution at low-y improved, the
discussions on likelihood and also earth absorption are expanded, added a
needed minus sign in Eq. 17 of v
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