1,207 research outputs found
Intercomparison of ambient acoustic spectra in inland and coastal waters
This paper compares the observed ambient sound levels at two very different sites, relating both to independent estimates of wind speed and rain rate. The spectra for wind-only conditions at the two sites show great differences, especially at low wind speed. The spectra associated with rain were sufficiently different from the wind-only spectra (either in terms of spectral slope or the intensity at 14.5 kHz) to support the development of a generic rather than site-specific rain detection algorithm
Recommended from our members
A few-group delayed neutron model based on a consistent set of decay constants
As part of an international effort, the Los Alamos National Laboratory has been asked to (1) determine if there is a set of dominant precursors that are common to all fissionable isotopes and all incident neutron energies, (2) expand the existing experimentally-measured few-group models commonly used in the nuclear industry into their 8-group equivalent using a consistent set of decay constants corresponding to these dominant precursors, and (3) formulate new group spectra for the equivalent 8-group model. In response to this request, LANL has calculated the theoretical delayed neutron yield for 14 different isotopes using three different incident neutron spectra (i.e., thermal, fast, and 14.1 MeV) using the current fission-yield and emission probability data found in ENDF-VI. An example of these results is shown in a figure in which the theoretical delayed neutron yields for the 271 precursors produced during thermal fission of {sup 235}U are plotted against the half-lives of the precursors. By comparing the results of all 14 isotopes, a preliminary set of precursors has been identified that are dominant within the various half-life regimes of the delayed neutron precursors. Also plotted on a figure are the group yields of the 8-group equivalent model of Keepin`s 6-group model. And finally, an example of the delayed neutron spectra for group 7 in the 8-group equivalent model is shown. A final report summarizing all results is expected to be released for review by the international steering committee by the summer of 1998
Dynamical symmetry breaking through AI: the dimer self-trapping transition
The nonlinear dimer obtained through the nonlinear Schrödinger equation has been a workhorse for the discovery the role nonlinearity plays in strongly interacting systems. While the analysis of the stationary states demonstrates the onset of a symmetry broken state for some degree of nonlinearity, the full dynamics maps the system into an effective [Formula: see text] model. In this later context, the self-trapping transition is an initial condition-dependent transfer of a classical particle over a barrier set by the nonlinear term. This transition that has been investigated analytically and mathematically is expressed through the hyperbolic limit of Jacobian elliptic functions. The aim of this work is to recapture this transition through the use of methods of Artificial Intelligence (AI). Specifically, we used a physics motivated machine learning model that is shown to be able to capture the original dynamic self-trapping transition and its dependence on initial conditions. Exploitation of this result in the case of the nondegenerate nonlinear dimer gives additional information on the more general dynamics and helps delineate linear from nonlinear localization. This work shows how AI methods may be embedded in physics and provide useful tools for discovery.Boston UniversityFirst author draf
Genome-wide mega-analysis identifies 16 loci and highlights diverse biological mechanisms in the common epilepsies
sem informaçãoThe epilepsies affect around 65 million people worldwide and have a substantial missing heritability component. We report a genome-wide mega-analysis involving 15,212 individuals with epilepsy and 29,677 controls, which reveals 16 genome-wide significant91sem informaçãosem informaçãosem informaçã
Post-Newtonian Gravitational Radiation
1 Introduction 2 Multipole Decomposition 3 Source Multipole Moments 4
Post-Minkowskian Approximation 5 Radiative Multipole Moments 6 Post-Newtonian
Approximation 7 Point-Particles 8 ConclusionComment: 46 pages, in Einstein's Field Equations and Their Physical
Implications, B. Schmidt (Ed.), Lecture Notes in Physics, Springe
Higgs-boson production associated with a bottom quark at hadron colliders with SUSY-QCD corrections
The Higgs boson production p p (p\bar p) -> b h +X via b g -> b h at the LHC,
which may be an important channel for testing the bottom quark Yukawa coupling,
is subject to large supersymmetric quantum corrections. In this work the
one-loop SUSY-QCD corrections to this process are evaluated and are found to be
quite sizable in some parameter space. We also study the behavior of the
corrections in the limit of heavy SUSY masses and find the remnant effects of
SUSY-QCD. These remnant effects, which are left over in the Higgs sector by the
heavy sparticles, are found to be so sizable (for a light CP-odd Higgs and
large \tan\beta) that they might be observable in the future LHC experiment.
The exploration of such remnant effects is important for probing SUSY,
especially in case that the sparticles are too heavy (above TeV) to be directly
discovered at the LHC.Comment: Results for the Tevatron adde
- …