48,375 research outputs found
Choosing Prevention Products: Questions to Ask When Considering Sexual and Relationship Violence and Stalking Prevention Products
The purpose of this white paper is to provide guidance to university and college leaders on how to choose products that address concerns of sexual and relationship violence and stalking from the perspective of prevention
Exact Fermi coordinates for a class of spacetimes
We find exact Fermi coordinates for timelike geodesic observers for a class
of spacetimes that includes anti-de Sitter spacetime, de Sitter spacetime, the
constant density interior Schwarzschild spacetime with positive, zero, and
negative cosmological constant, and the Einstein static universe. Maximal
charts for Fermi coordinates are discussed.Comment: 15 page
NMR Measurements of Power-Law Behavior in the Spin-Wave and Critical Regions of Ferromagnetic EuO
Precision continuous-wave NMR measurements have been carried out over the
entire magnetization curve of EuO and are presented in tabular form. Two very
closely spaced resonances are observed and are attributed to domain and
domain-wall signals. Both of the signals are useful for analysis in the
spin-wave region. Only the domain signal is measurable above ~50K. The latter
is used for fitting Tc and the critical exponent beta. The critical-region fits
agree with previous measurements, within experimental error. The
low-temperature data exhibit a clear-cut T^2 behavior, at variance with the
expectations of conventional spin-wave theory. This result is discussed in
relation to two semi-empirical spin-wave schemes, one formulated by N.
Bykovetz, and one by U. Koebler. The NMR signal at 4.2K gives no indication of
a quadrupole splitting, in contradiction to the interpretation of several
previous spin-echo NMR spectra observed in EuO. This issue remains unresolved.Comment: 3 pages, 2 figures, 3 tables. in Proceedings of the 11TH Joint
MMM-Intermag Conference, Washington, DC, 201
Voltage and temperature dependence of the grain boundary tunneling magnetoresistance in manganites
We have performed a systematic analysis of the voltage and temperature
dependence of the tunneling magnetoresistance (TMR) of grain boundaries (GB) in
the manganites. We find a strong decrease of the TMR with increasing voltage
and temperature. The decrease of the TMR with increasing voltage scales with an
increase of the inelastic tunneling current due to multi-step inelastic
tunneling via localized defect states in the tunneling barrier. This behavior
can be described within a three-current model for magnetic tunnel junctions
that extends the two-current Julliere model by adding an inelastic,
spin-independent tunneling contribution. Our analysis gives strong evidence
that the observed drastic decrease of the GB-TMR in manganites is caused by an
imperfect tunneling barrier.Comment: to be published in Europhys. Lett., 8 pages, 4 figures (included
Addressing Alcohol\u27s Role in Campus Sexual Assault: A Toolkit by and for Prevention Specialists
This toolkit provides specific guidance on addressing alcohol\u27s role in campus sexual assault, centering Sexual Assault Prevention Specialists as the intended audience
Heat pipe dynamic behavior
The vapor flow in a heat pipe was mathematically modeled and the equations governing the transient behavior of the core were solved numerically. The modeled vapor flow is transient, axisymmetric (or two-dimensional) compressible viscous flow in a closed chamber. The two methods of solution are described. The more promising method failed (a mixed Galerkin finite difference method) whereas a more common finite difference method was successful. Preliminary results are presented showing that multi-dimensional flows need to be treated. A model of the liquid phase of a high temperature heat pipe was developed. The model is intended to be coupled to a vapor phase model for the complete solution of the heat pipe problem. The mathematical equations are formulated consistent with physical processes while allowing a computationally efficient solution. The model simulates time dependent characteristics of concern to the liquid phase including input phase change, output heat fluxes, liquid temperatures, container temperatures, liquid velocities, and liquid pressure. Preliminary results were obtained for two heat pipe startup cases. The heat pipe studied used lithium as the working fluid and an annular wick configuration. Recommendations for implementation based on the results obtained are presented. Experimental studies were initiated using a rectangular heat pipe. Both twin beam laser holography and laser Doppler anemometry were investigated. Preliminary experiments were completed and results are reported
- …