5,262 research outputs found
Auditory neuroscience: Development, transduction and integration
Hearing underlies our ability to locate sound sources in the environment, our appreciation of music, and our ability to communicate. Participants in the National Academy of Sciences colloquium on Auditory Neuroscience: Development, Transduction, and Integration presented research results bearing on four key issues in auditory research. How does the complex inner ear develop? How does the cochlea transduce sounds into electrical signals? How does the brain's ability to compute the location of a sound source develop? How does the forebrain analyze complex sounds, particularly species-specific communications? This article provides an introduction to the papers stemming from the meeting
Electric Conductance of Rh Atomic Contacts under Electrochemical Potential Control
The electric conductance of Rh atomic contacts was investigated under the
electrochemical potential control. The conductance histogram of Rh atomic
contacts varied with the electrochemical potential. When the electrochemical
potential of the contact was kept at = 0.1 V vs. Ag/AgCl (Rh
potential), the conductance histogram did not show any features. At =
-0.1 V (under potential deposited hydrogen potential), the conductance
histogram showed a feature around 2.3 ( =2), which
agreed with the conductance value of a clean Rh atomic contact, which was
observed in ultrahigh vacuum at low temperature. At = -0.25 V (over
potential deposited hydrogen potential), the conductance histogram showed
features around 0.3 and 1.0 . The conductance behavior of the Rh atomic
contact was discussed by comparing previously reported results of other metals,
Au, Ag, Cu, Pt, Pd, Ni, Co, and Fe. The conductance behavior of the metal
atomic contacts related with the strength of the interaction between hydrogen
and metal surface.Comment: 5 pages, 4 figures, Phys. Rev. B, in press
Simple Two-Dimensional Model for the Elastic Origin of Cooperativity among Spin States of Spin-Crossover Complexes
We study the origin of the cooperative nature of spin crossover (SC) between
low spin (LS) and high spin (HS) states from the view point of elastic
interactions among molecules. As the size of each molecule changes depending on
its spin state, the elastic interaction among the lattice distortions provides
the cooperative interaction of the spin states. We develop a simple model of SC
with intra and intermolecular potentials which accounts for the elastic
interaction including the effect of the inhomogeneity of the spin states, and
apply constant temperature molecular dynamics based on the Nos\'e-Hoover
formalism. We demonstrate that, with increase of the strength of the
intermolecular interactions, the temperature dependence of the HS component
changes from a gradual crossover to a first-order transition.Comment: 4 pages, 4 figure
Nielsen-Olesen strings in Supersymmetric models
We investigate the behaviour of a model with two oppositely charged scalar
fields. In the Bogomol'nyi limit this may be seen as the scalar sector of N=1
supersymmetric QED, and it has been shown that cosmic strings form. We examine
numerically the model out of the Bogomol'nyi limit, and show that this remains
the case. We then add supersymmetry-breaking mass terms to the supersymmetric
model, and show that strings still survive.
Finally we consider the extension to N=2 supersymmetry with
supersymmetry-breaking mass terms, and show that this leads to the formation of
stable cosmic strings, unlike in the unbroken case.Comment: 7 pages, 2 figues, uses revtex4; minor typos corrected; references
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Effect of quantum fluctuations on topological excitations and central charge in supersymmetric theories
The effect of quantum fluctuations on Bogomol'nyi-Prasad-Sommerfield
(BPS)-saturated topological excitations in supersymmetric theories is studied.
Focus is placed on a sequence of topological excitations that derive from the
same classical soliton or vortex in lower dimensions and it is shown that their
quantum characteristics, such as the spectrum and profile, differ critically
with the dimension of spacetime. In all the examples examined the supercharge
algebra retains its classical form although short-wavelength fluctuations may
modify the operator structure of the central charge, yielding an anomaly. The
central charge, on taking the expectation value, is further affected by
long-wavelength fluctuations, and this makes the BPS-excitation spectra only
approximately calculable in some low-dimensional theories. In four dimensions,
in contrast, holomorphy plays a special role in stabilizing the BPS-excitation
spectra against quantum corrections. The basic tool in our study is the
superfield supercurrent, from which the supercharge algebra with a central
extension is extracted in a supersymmetric setting. A general method is
developed to determine the associated superconformal anomaly by considering
dilatation directly in superspace.Comment: 10 pages, Revtex, to appear in PR
Hierarchical clustering and formation of power-law correlation in 1-dimensional self-gravitating system
The process of formation of fractal structure in one-dimensional
self-gravitating system is examined numerically. It is clarified that
structures created in small spatial scale grow up to larger scale through
clustering of clusters, and form power-law correlation.Comment: 9pages,4figure
Three reversible states controlled on a gold monoatomic contact by the electrochemical potential
Conductance of an Au mono atomic contact was investigated under the
electrochemical potential control. The Au contact showed three different
behaviors depending on the potential: 1 ( = ), 0.5
and not-well defined values below 1 were shown when the
potential of the contact was kept at -0.6 V (double layer potential), -1.0 V
(hydrogen evolution potential), and 0.8 V (oxide formation potential) versus
Ag/AgCl in 0.1 M NaSO solution, respectively. These three
reversible states and their respective conductances could be fully controlled
by the electrochemical potential. These changes in the conductance values are
discussed based on the proposed structure models of hydrogen adsorbed and
oxygen incorporated on an Au mono atomic contact.Comment: 8 pages, 4 figures, to be appeared in Physical Review
Formation of fractal structure in many-body systems with attractive power-law potentials
We study the formation of fractal structure in one-dimensional many-body
systems with attractive power-law potentials. Numerical analysis shows that the
range of the index of the power for which fractal structure emerges is limited.
Dependence of the growth rate on wavenumber and power-index is obtained by
linear analysis of the collisionless Boltzmann equation, which supports the
numerical results.Comment: accepted by PR
Gravitino condensation in fivebrane backgrounds
We calculate the tension of the D3-brane in the fivebrane background which is
described by the exactly solvable SU(2)_k x U(1) world-sheet conformal field
theory with large Kac-Moody level k. The D3-brane tension is extracted from the
amplitude of one closed string exchange between two parallel D3-branes, and the
amplitude is calculated by utilizing the open-closed string duality. The
tension of the D3-brane in the background does not coincide with the one in the
flat space-time even in the flat space-time limit: k -> infinity. The finite
curvature effect should vanish in the flat space-time limit and only the
topological effect can remain. Therefore, the deviation indicates the
condensation of gravitino and/or dilatino which has been expected in the
fivebrane background as a gravitational instanton.Comment: 16 pages, 1 figur
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