5,498 research outputs found
Absence of platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) in vivo increases resistance to Salmonella enterica serovar Typhimurium in mice.
PECAM-1/CD31 is known to regulate inflammatory responses and exhibit pro- and anti-inflammatory functions. This study was designed to determine the functional role of PECAM-1 in susceptibility to murine primary in vivo infection with Salmonella enterica serovar Typhimurium and in in vitro inflammatory responses of peritoneal macrophages. Lectin profiling showed that cellular PECAM-1 and recombinant human PECAM-1-Ig chimera contain high levels of mannose sugars and N-acetylglucosamine. Consistent with this carbohydrate pattern, both recombinant human and murine PECAM-1-Ig chimeras were shown to bind S. Typhimurium in a dose-dependent manner in vitro. Using oral and fecal-oral transmission models of S. Typhimurium SL1344 infection, PECAM-1-/- mice were found to be more resistant to S. Typhimurium infection than wild-type (WT) C57BL/6 mice. While fecal shedding of S. Typhimurium was comparable in wild-type and PECAM-1-/- mice, the PECAM-1-deficient mice had lower bacterial loads in systemic organs such as liver, spleen, and mesenteric lymph nodes than WT mice, suggesting that extraintestinal dissemination was reduced in the absence of PECAM-1. This reduced bacterial load correlated with reduced tumor necrosis factor (TNF), interleukin-6 (IL-6), and monocyte chemoattractant protein (MCP) levels in sera of PECAM-1-/- mice. Following in vitro stimulation of macrophages with either whole S. Typhimurium, lipopolysaccharide (LPS) (Toll-like receptor 4 [TLR4] ligand), or poly(I·C) (TLR3 ligand), production of TNF and IL-6 by PECAM-1-/- macrophages was reduced. Together, these results suggest that PECAM-1 may have multiple functions in resistance to infection with S. Typhimurium, including binding to host cells, extraintestinal spread to deeper tissues, and regulation of inflammatory cytokine production by infected macrophages
Josephson Current between Triplet and Singlet Superconductors
The Josephson effect between triplet and singlet superconductors is studied.
Josephson current can flow between triplet and singlet superconductors due to
the spin-orbit coupling in the spin-triplet superconductor but it is finite
only when triplet superconductor has , where and
are the perpendicular components of orbital angular momentum and spin angular
momentum of the triplet Cooper pairs, respectively. The recently observed
temperature and orientational dependence of the critical current through a
Josephson junction between UPt and Nb is investigated by considering a
non-unitary triplet state.Comment: 4 pages, no figure
Magnetic Field Effect on the Supercurrent of an SNS junction
In this paper we study the effect of a Zeeman field on the supercurrent of a
mesoscopic SNS junction. It is shown that the supercurrent suppression is due
to a redistribution of current-carrying states in energy space. A dramatic
consequence is that (part of the) the suppressed supercurrent can be recovered
with a suitable non-equilibrium distribution of quasiparticles.Comment: 4 figures in postscrip
Electronic State and Magnetic Susceptibility in Orbitally Degenerate (J=5/2) Periodic Anderson Model
Magnetic susceptibility in a heavy fermion systemis composed of the Pauli
term (\chi_P) and the Van-Vleck term (\chi_V). The latter comes from the
interband excitation, where f-orbital degeneracy is essential. In this work, we
study \chi_P and \chi_V in the orbitally degenerate (J=5/2) periodic Anderson
model for both the metallic and insulating cases. The effect of the correlation
between f-electrons is investigated using the self-consistent second-order
perturbation theory. The main results are as follows. (i) Sixfold degenerate
model: both \chi_P and \chi_V are enhanced by a factor of 1/z (z is the
renormalization constant). (ii) Nondegenerate model: only \chi_P is enhanced by
1/z. Thus, orbital degeneracy is indispensable for enhancement of \chi_V.
Moreover, orbital degeneracy reduces the Wilson ratio and stabilizes a
nonmagnetic Fermi liquid state.Comment: 4 pages, revtex, to be published in J. Phys. Soc. Jpn. (No.8
The Black Hole-Bulge Relationship in Luminous Broad-Line Active Galactic Nuclei and Host Galaxies
We have measured the stellar velocity dispersions (\sigma_*) and estimated
the central black hole (BH) masses for over 900 broad-line active galactic
nuclei (AGNs) observed with the Sloan Digital Sky Survey. The sample includes
objects which have redshifts up to z=0.452, high quality spectra, and host
galaxy spectra dominated by an early-type (bulge) component. The AGN and host
galaxy spectral components were decomposed using an eigenspectrum technique.
The BH masses (M_BH) were estimated from the AGN broad-line widths, and the
velocity dispersions were measured from the stellar absorption spectra of the
host galaxies. The range of black hole masses covered by the sample is
approximately 10^6 < M_BH < 10^9 M_Sun. The host galaxy luminosity-velocity
dispersion relationship follows the well-known Faber-Jackson relation for
early-type galaxies, with a power-law slope 4.33+-0.21. The estimated BH masses
are correlated with both the host luminosities (L_{H}) and the stellar velocity
dispersions (\sigma_*), similar to the relationships found for low-redshift,
bulge-dominated galaxies. The intrinsic scatter in the correlations are large
(~0.4 dex), but the very large sample size allows tight constraints to be
placed on the mean relationships: M_BH ~ L_H^{0.73+-0.05} and M_BH ~
\sigma_*^{3.34+-0.24}. The amplitude of the M_BH-\sigma_* relation depends on
the estimated Eddington ratio, such that objects with larger Eddington ratios
have smaller black hole masses than expected at a given velocity dispersion.Comment: Accepted for publication in A
Deformation of Quantum Dots in the Coulomb Blockade Regime
We extend the theory of Coulomb blockade oscillations to quantum dots which
are deformed by the confining potential. We show that shape deformations can
generate sequences of conductance resonances which carry the same internal
wavefunction. This fact may cause strong correlations of neighboring
conductance peaks. We demonstrate the relevance of our results for the
interpretation of recent experiments on semiconductor quantum dots.Comment: 4 pages, Revtex, 4 postscript figure
Reynolds number influences in aeronautics
Reynolds number, a measure of the ratio of inertia to viscous forces, is a fundamental similarity parameter for fluid flows and therefore, would be expected to have a major influence in aerodynamics and aeronautics. Reynolds number influences are generally large, but monatomic, for attached laminar (continuum) flow; however, laminar flows are easily separated, inducing even stronger, non-monatomic, Reynolds number sensitivities. Probably the strongest Reynolds number influences occur in connection with transitional flow behavior. Transition can take place over a tremendous Reynolds number range, from the order of 20 x 10(exp 3) for 2-D free shear layers up to the order of 100 x 10(exp 6) for hypersonic boundary layers. This variability in transition behavior is especially important for complex configurations where various vehicle and flow field elements can undergo transition at various Reynolds numbers, causing often surprising changes in aerodynamics characteristics over wide ranges in Reynolds number. This is further compounded by the vast parameterization associated with transition, in that any parameter which influences mean viscous flow development (e.g., pressure gradient, flow curvature, wall temperature, Mach number, sweep, roughness, flow chemistry, shock interactions, etc.), and incident disturbance fields (acoustics, vorticity, particulates, temperature spottiness, even electro static discharges) can alter transition locations to first order. The usual method of dealing with the transition problem is to trip the flow in the generally lower Reynolds number wind tunnel to simulate the flight turbulent behavior. However, this is not wholly satisfactory as it results in incorrectly scaled viscous region thicknesses and cannot be utilized at all for applications such as turbine blades and helicopter rotors, nacelles, leading edge and nose regions, and High Altitude Long Endurance and hypersonic airbreathers where the transitional flow is an innately critical portion of the problem
The use of smart phones and their mobile applications among older adults in Hong Kong: An exploratory study
The purpose of this study was to explore social participation using smart phones by the older population in Hong Kong. The present study was conducted from 10-June-2013 to 16-August-2013. It was a cross-sectional survey study, and data were collected from street interviews. Potential participants were approached and invited to respond to a questionnaire. The locations for collecting data were evenly distributed on Hong Kong Island, Kowloon, and the New Territories. The size of the samples for Hong Kong Island, Kowloon, and the New Territories were calculated based on their respective proportion of the Hong Kong population in 2011. The estimated time to complete the questionnaire was approximately 10 minutes. The questionnaire included questions on demographic data and the use of smart phones and their related features. A total of 982 participants were interviewed, 46% of whom were male and 54% female. The participants were divided into the following two groups: the young-old (age 50-69) and the old-old (age 70 or above). The mean age was 67.93±10.386. The findings showed that, in comparison with the young-old group (age 50 to 69), a smaller percentage of the old-old group (70 and over) used smart phones and mobile messaging applications to communicate with others. There were no differences in patterns with regard to the type and frequency of the mobile applications being used. However, a smaller percentage of the old-old group had installed the mobile app by themselves and introduced the mobile app to others. This study reveals the behavioral patterns of the young-old and the old-old groups in the use of mobile devices to communicate. The young-old and old-old groups exhibited the same patterns in terms of the types and frequency of the mobile apps used; however, a smaller percentage of the old-old group used mobile apps to communicate. Different educational programs on the importance of social support should be established, and the promotional strategies for these programs need to be tailored to older adults
Pseudogap Formation in the Symmetric Anderson Lattice Model
We present self-consistent calculations for the self-energy and magnetic
susceptibility of the 2D and 3D symmetric Anderson lattice Hamiltonian, in the
fluctuation exchange approximation. At high temperatures, strong f-electron
scattering leads to broad quasiparticle spectral functions, a reduced
quasiparticle band gap, and a metallic density of states. As the temperature is
lowered, the spectral functions narrow and a pseudogap forms at the
characteristic temperature at which the width of the quasiparticle
spectral function at the gap edge is comparable to the renormalized activation
energy. For , the pseudogap is approximately equal to the
hybridization gap in the bare band structure. The opening of the pseudogap is
clearly apparent in both the spin susceptibility and the compressibility.Comment: RevTeX - 14 pages and 7 figures (available on request),
NRL-JA-6690-94-002
The stabilizing role of itinerant ferromagnetism in inter-granular cohesion in iron
We present a simple, general energy functional for ferromagnetic materials
based upon a local spin density extension to the Stoner theory of itinerant
ferromagnetism. The functional reproduces well available ab initio results and
experimental interfacial energies for grain boundaries in iron. The model shows
that inter-granular cohesion along symmetric tilt boundaries in iron is
dependent upon strong magnetic structure at the interface, illuminates the
mechanisms underlying this structure, and provides a simple explanation for
relaxation of the atomic structure at these boundaries.Comment: In review at Phys. Rev. Lett. Submitted 23 September 1997; revised 16
March 199
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