17,650 research outputs found
Effects of a traffic noise background on judgements of aircraft noise
A study was conducted in which subjects judged aircraft noises in the presence of road traffic background noise. Two different techniques for presenting the background noises were evaluated. For one technique, the background noise was continuous over the whole of a test session. For the other, the background noise was changed with each aircraft noise. A range of aircraft noise levels and traffic noise levels were presented to simulate typical indoor levels
The role of the energy equation in the fragmentation of protostellar discs during stellar encounters
In this paper, we use high-resolution smoothed particle hydrodynamics (SPH)
simulations to investigate the response of a marginally stable self-gravitating
protostellar disc to a close parabolic encounter with a companion discless
star. Our main aim is to test whether close brown dwarfs or massive planets can
form out of the fragmentation of such discs. We follow the thermal evolution of
the disc by including the effects of heating due to compression and shocks and
a simple prescription for cooling and find results that contrast with previous
isothermal simulations. In the present case we find that fragmentation is
inhibited by the interaction, due to the strong effect of tidal heating, which
results in a strong stabilization of the disc. A similar behaviour was also
previously observed in other simulations involving discs in binary systems. As
in the case of isolated discs, it appears that the condition for fragmentation
ultimately depends on the cooling rate.Comment: 9 pages, 10 figures, accepted in MNRA
Administering Justice in Montana\u27s Rural Courts
Administering Justice in Montana\u27s Rural Court
Repeating Earthquakes as Low-Stress-Drop Events at a Border between Locked and Creeping Fault Patches
The source of repeating earthquakes on creeping faults is modeled as a
weak asperity at a border between much larger locked and creeping patches on the
fault plane. The x^(-1/2) decrease in stress concentration with distance x from the boundaryis shown to lead directly to the observed scaling <T>~<M0>^(1/6) between the average repeat time and average scalar moment for a repeating sequence. The stress drop in such small events at the border depends on the size of the large locked patch. For a circular patch of radius R and representative fault parameters, Dr 7.6(m/R)3/5
MPa, which yields stress drops between 0.08 and 0.5 MPa (0.8–5 bars) for R between
2 km and 100 m. These low stress drops are consistent with estimates of stress drop
for small earthquakes based on their seismic spectra. However, they are orders of
magnitude smaller than stress drops calculated under the assumption that repeating
sources are isolated stuck asperities on an otherwise creeping fault plane, whose
seismic slips keep pace with the surrounding creep rate. Linear streaks of microearthquakes
observed on creeping fault planes are trivially explained by the present model
as alignments on the boundaries between locked and creeping patches
Tunnel junctions of unconventional superconductors
The phenomenology of Josephson tunnel junctions between unconventional
superconductors is developed further. In contrast to s-wave superconductors,
for d-wave superconductors the direction dependence of the tunnel matrix
elements that describe the barrier is relevant. We find the full I-V
characteristics and comment on the thermodynamical properties of these
junctions. They depend sensitively on the relative orientation of the
superconductors. The I-V characteristics differ from the normal s-wave RSJ-like
behavior.Comment: 4 pages, revtex, 4 (encapsulated postscript) figures (figures
replaced
Fractoluminescence characterization of the energy dissipated during fast fracture of glass
Fractoluminescence experiments are performed on two kinds of silicate
glasses. All the light spectra collected during dynamic fracture reveal a black
body radiator behaviour, which is interpreted as a crack velocity-dependent
temperature rise close to the crack tip. Crack velocities are estimated to be
of the order of 1300 m.s and fracture process zones are shown to extend
over a few nanometers.Comment: Accepted for publication in Europhysics Letters; 5 pages; 4 figure
Random wave functions and percolation
Recently it was conjectured that nodal domains of random wave functions are
adequately described by critical percolation theory. In this paper we
strengthen this conjecture in two respects. First, we show that, though wave
function correlations decay slowly, a careful use of Harris' criterion confirms
that these correlations are unessential and nodal domains of random wave
functions belong to the same universality class as non critical percolation.
Second, we argue that level domains of random wave functions are described by
the non-critical percolation model.Comment: 13 page
The influence of chiral surface states on the London penetration depth in SrRuO
The London penetration depth for the unconventional superconductor
SrRuO is analyzed assuming an order parameter which breaks time
reversal symmetry and parity simultaneously. Such a superconducting state
possesses chiral quasiparticle states with subgap energies at the surface. We
show that these subgap states can give a significant contribution to the
low-temperature behavior of the London penetration depth yielding a
power-law even though bulk quasiparticle spectrum is gapped. The presence of
several electron bands gives rise to interband transition among the subgap
surface states and influences the properties of the surface impedance.
Furthermore, the surface states lead also to a non-linear Meissner effect.Comment: 4 pages, 1 figure, the definition of the Nambu field operator
introduced, and some typos correcte
Pigeons Choose to Gamble in a Categorical Discrimination Task
In slot-machine play, near wins are stimuli that visually approximate winning stimuli but deliver no reinforcers. In two experiments, a categorical discrimination task was embedded in a concurrent chain to investigate how near wins affect preference for probabilistic versus certain food. Pecking in variable-interval initial links produced access to a fixed-ratio (FR) 1-FR 1-FR 1 chain. When all links were red, the chain was a “win” that produced access to food. A “clear loss” chain involved three green stimuli, and in a “near win,” key colors during successive FR 1 links were red, red, and green. In Experiment 1, the magnitude and probability of reinforcement were varied across conditions with and without near wins. Response allocation was sensitive to changes in reinforcer magnitude and probability. Generalized matching analyses revealed a consistent bias for probabilistic over certain outcomes, but only when they included near wins. Response rates on near-win trials were also intermediate to that of clear losses and wins. Near-win probability was varied across conditions of Experiment 2 and probability of near wins was positively associated with bias for probabilistic outcomes. The results from both experiments suggest that near wins encourage individuals to choose to gamble by functioning as conditioned reinforcers
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