3,469 research outputs found
Is simultaneous and --scaling in the quasi-elastic region accidental?
We study the and --scaling of the nuclear response at large momentum
transfer in order to understand how scaling based on very different
descriptions of the elementary interaction can occur simultaneously. We find
that the approximate validity of -scaling at low energy loss arises from
the coincidental behavior of the quasielastic and deep inelastic cross
sections.Comment: 4 pages, 3 Postscript figure
Performance of alkaline battery cells used in emergency locator transmitters
The characteristics of battery power supplies for emergency locator transmitters (ELT's) were investigated by testing alkaline zinc/manganese dioxide cells of the type typically used in ELT's. Cells from four manufacturers were tested. The cells were subjected to simulated environmental and load conditions representative of those required for survival and operation. Battery cell characteristics that may contribute to ELT malfunctions and limitations were evaluated. Experimental results from the battery cell study are discussed, and an evaluation of ELT performance while operating under a representative worst-case environmental condition is presented
Anomalous Spin Dynamics in Doped Quantum Antiferromagnets
Finite-temperature spin dynamics in planar t-J model is studied using the
method based on the Lanczos diagonalization of small systems. Dynamical spin
structure factor at moderate dopings shows the coexistence of free-fermion-like
and spin-fluctuation timescales. At T<J, the low-frequency and static
susceptibility show pronounced T dependence, supporting a scenario, related to
the marginal Fermi-liquid one, for the explanation of neutron-scattering and
NMR-relaxation experiments in cuprates. Calculated NMR relaxation rates
reasonably reproduce experimental ones.Comment: 10 pages + 4 figures, Postscript in uuencoded compressed tar file,
IJS-TP-94/2
The Momentum Distribution of Liquid He
We present high-resolution neutron Compton scattering measurements of liquid
He below its renormalized Fermi temperature. Theoretical predictions are in
excellent agreement with the experimental data when instrumental resolution and
final state effects are accounted for. Our results resolve the long-standing
inconsistency between theoretical and experimental estimates of the average
atomic kinetic energy.Comment: 5 pages, 4 figure
Spin Dependence of Correlations in Two-Dimensional Quantum Heisenberg Antiferromagnets
We present a series expansion study of spin-S square-lattice Heisenberg
antiferromagnets. The numerical data are in excellent agreement with recent
neutron scattering measurements. Our key result is that the correlation length
for S>1/2 strongly deviates from the exact T->0 (renormalized classical, or RC)
scaling prediction for all experimentally and numerically accessible
temperatures. We note basic trends with S of the experimental and series
expansion correlation length data and propose a scaling crossover scenario to
explain them.Comment: 5 pages, REVTeX file. PostScript file for the paper with embedded
figures available via WWW at http://xxx.lanl.gov/ps/cond-mat/9503143
Layer- and bulk roton excitations of 4He in porous media
We examine the energetics of bulk and layer-roton excitations of 4He in
various porous medial such as aerogel, Geltech, or Vycor, in order to find out
what conclusions can be drawn from experiments on the energetics about the
physisorption mechanism. The energy of the layer-roton minimum depends
sensitively on the substrate strength, thus providing a mechanism for a direct
measurement of this quantity. On the other hand, bulk-like roton excitations
are largely independent of the interaction between the medium and the helium
atoms, but the dependence of their energy on the degree of filling reflects the
internal structure of the matrix and can reveal features of 4He at negative
pressures. While bulk-like rotons are very similar to their true bulk
counterparts, the layer modes are not in close relation to two-dimensional
rotons and should be regarded as a third, completely independent kind of
excitation
Inter-Annual Variation in Hydroperiod Affects Periphyton Standing Crop and the Associated Macroinvertebrate Community in the Everglades
Monitoring Fish Communities and Populations on the Eastern Boundary of Everglades National Park
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