13,872 research outputs found
Neuron analysis of visual perception
The receptive fields of single cells in the visual system of cat and squirrel monkey were studied investigating the vestibular input affecting the cells, and the cell's responses during visual discrimination learning process. The receptive field characteristics of the rabbit visual system, its normal development, its abnormal development following visual deprivation, and on the structural and functional re-organization of the visual system following neo-natal and prenatal surgery were also studied. The results of each individual part of each investigation are detailed
Muonium as a shallow center in GaN
A paramagnetic muonium (Mu) state with an extremely small hyperfine parameter
was observed for the first time in single-crystalline GaN below 25 K. It has a
highly anisotropic hyperfine structure with axial symmetry along the [0001]
direction, suggesting that it is located either at a nitrogen-antibonding or a
bond-centered site oriented parallel to the c-axis. Its small ionization energy
(=< 14 meV) and small hyperfine parameter (--10^{-4} times the vacuum value)
indicate that muonium in one of its possible sites produces a shallow state,
raising the possibility that the analogous hydrogen center could be a source of
n-type conductivity in as-grown GaN.Comment: 4 figures, to be published in Phys. Rev. Letter
Energy-efficiency improvements for optical access
This article discusses novel approaches to improve energy efficiency of different optical access technologies, including time division multiplexing passive optical network (TDM-PON), time and wavelength division multiplexing PON (TWDM-PON), point-to-point (PTP) access network, wavelength division multiplexing PON (WDM-PON), and orthogonal frequency division multiple access PON (OFDMA-PON). These approaches include cyclic sleep mode, energy-efficient bit interleaving protocol, power reduction at component level, or frequency band selection. Depending on the target optical access technology, one or a combination of different approaches can be applied
eHealth interventions for people with chronic kidney disease
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: This review aims to look at the benefits and harms of using eHealth interventions in the CKD population
Threshold effects in excited charmed baryon decays
Motivated by recent results on charmed baryons from CLEO and FOCUS, we
reexamine the couplings of the orbitally excited charmed baryons. Due to its
proximity to the [Sigma_c pi] threshold, the strong decays of the
Lambda_c(2593) are sensitive to finite width effects. This distorts the shape
of the invariant mass spectrum in Lambda_{c1}-> Lambda_c pi^+pi^- from a simple
Breit-Wigner resonance, which has implications for the experimental extraction
of the Lambda_c(2593) mass and couplings. We perform a fit to unpublished CLEO
data which gives M(Lambda_c(2593)) - M(Lambda_c) = 305.6 +- 0.3 MeV and h2^2 =
0.24^{+0.23}_{-0.11}, with h2 the Lambda_{c1}-> Sigma_c pi strong coupling in
the chiral Lagrangian. We also comment on the new orbitally excited states
recently observed by CLEO.Comment: 9 pages, 3 figure
Comment on ``A new efficient method for calculating perturbative energies using functions which are not square integrable'': regularization and justification
The method recently proposed by Skala and Cizek for calculating perturbation
energies in a strict sense is ambiguous because it is expressed as a ratio of
two quantities which are separately divergent. Even though this ratio comes out
finite and gives the correct perturbation energies, the calculational process
must be regularized to be justified. We examine one possible method of
regularization and show that the proposed method gives traditional quantum
mechanics results.Comment: 6 pages in REVTeX, no figure
Multiplpe Choice Minority Game With Different Publicly Known Histories
In the standard Minority Game, players use historical minority choices as the
sole public information to pick one out of the two alternatives. However,
publishing historical minority choices is not the only way to present global
system information to players when more than two alternatives are available.
Thus, it is instructive to study the dynamics and cooperative behaviors of this
extended game as a function of the global information provided. We numerically
find that although the system dynamics depends on the kind of public
information given to the players, the degree of cooperation follows the same
trend as that of the standard Minority Game. We also explain most of our
findings by the crowd-anticrowd theory.Comment: Extensively revised, to appear in New J Phys, 7 pages with 4 figure
Using social networking sites for communicable disease control: innovative contact tracing or breach of confidentiality?
Social media applications such as Twitter, YouTube and Facebook have attained huge popularity, with more than three billion people and organizations predicted to have a social networking account by 2015. Social media offers a rapid avenue of communication with the public and has potential benefits for communicable disease control and surveillance. However, its application in everyday public health practice raises a number of important issues around confidentiality and autonomy. We report here a case from local level health protection where the friend of an individual with meningococcal septicaemia used a social networking site to notify potential contacts
Fractal Formation Of A Y-Ba-Cu-O Thin-Film On Srtio3
Fractal formation has been observed after thermal annealing of the rf-sputtered Y-Ba-Cu-O thin film on SrTiO3 substrate. Through energy-dispersive x-ray analysis, it was found that the composition of the fractal was YBa2Cu3Ox and the surrounding film composition was Y2Ba2Cu3Ox. The fractal dimensions D ranging from 1.26 to 1.65 were obtained using the standard sandbox method with different thresholds
Twisted and Nontwisted Bifurcations Induced by Diffusion
We discuss a diffusively perturbed predator-prey system. Freedman and
Wolkowicz showed that the corresponding ODE can have a periodic solution that
bifurcates from a homoclinic loop. When the diffusion coefficients are large,
this solution represents a stable, spatially homogeneous time-periodic solution
of the PDE. We show that when the diffusion coefficients become small, the
spatially homogeneous periodic solution becomes unstable and bifurcates into
spatially nonhomogeneous periodic solutions.
The nature of the bifurcation is determined by the twistedness of an
equilibrium/homoclinic bifurcation that occurs as the diffusion coefficients
decrease. In the nontwisted case two spatially nonhomogeneous simple periodic
solutions of equal period are generated, while in the twisted case a unique
spatially nonhomogeneous double periodic solution is generated through
period-doubling.
Key Words: Reaction-diffusion equations; predator-prey systems; homoclinic
bifurcations; periodic solutions.Comment: 42 pages in a tar.gz file. Use ``latex2e twisted.tex'' on the tex
files. Hard copy of figures available on request from
[email protected]
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