57,853 research outputs found
A longitudinal study of migration propensities for mixed-ethnic unions in England and Wales
This research was funded by the ESRC under the Understanding Population Trends and Processes (UPTAP) programme (Award Ref: RES-163-25-0045).Most studies investigating residential segregation of ethnic minorities ignore the fact that the majority of adults live in couples. In recent years there has been a growth in the number of mixed-ethnic unions that involve a minority member and a white member. To our knowledge, hardly any research has been undertaken to explicitly examine whether the ethnic mix within households has an impact on the residential mobility of households in terms of the ethnic mix of destination neighbourhoods. Our study addresses this research gap and examines the tendencies of mobility among mixed-ethnic unions in comparison with their co-ethnic peers. We used data from the Longitudinal Study for England and Wales. Our statistical analysis supports the spatial assimilation theory; ethnic minorities move towards less deprived areas and to a lesser extent also towards less ethnically concentrated areas. However, the types of destination neighbourhood of minority people living in mixed-ethnic unions varied greatly with the ethnicity of the ethnic minority partner.PostprintPeer reviewe
Microwave-mediated heat transport through a quantum dot
The thermoelectric effect in a quantum dot (QD) attached to two leads in the
presence of microwave fields is studied by using the Keldysh nonequilibrium
Green function technique. When the microwave is applied only on the QD and in
the linear-response regime, the main peaks in the thermoelectric figure of
merit and the thermopower are found to decrease, with the emergence of a set of
photon-induced peaks. Under this condition the microwave field can not generate
heat current or electrical bias voltage. Surprisingly, when the microwave field
is applied only to one (bright) lead and not to the other (dark) lead or the
QD, heat flows mostly from the dark to the bright lead, almost irrespectively
to the direction of the thermal gradient. We attribute this effect to
microwave-induced opening of additional transport channels below the Fermi
energy. The microwave field can change both the magnitude and the sign of the
electrical bias voltage induced by the temperature gradient.Comment: 5 figur
Asymmetry in Photoproduction
By adopting two models of strange and antistrange quark distributions inside
nucleon, the light-cone meson-baryon fluctuation model and the effective chiral
quark model, we calculate the asymmetry in photoproduction in
the framework of heavy-quark recombination mechanism. We find that the effect
of asymmetry of strange sea to the asymmetry is considerable and
depending on the different models. Therefore, we expect that with the further
study in electroproduction, e.g. at HERA and CEBAF, the experimental
measurements on the asymmetry may impose a strong restriction
on the strange-antistrange distribution asymmetry models.Comment: 4 pages, talk presented by I. Caprini at the International Conference
on QCD and Hadronic Physics, June 16-20 2005, Beijin
Early Tracking Behavior in Small-field Quintessence Models
We study several quintessence models which are singular at Q=0, and use a
simple initial constraint to see when they enter
tracking regime, disregarding the details of inflation. We find it can give
strong constraints for the inverse power-law potential ,
which has to enter tracking regime for . While for the
supergravity model , the constraint is much
weakened. For another kind inverse power-law potential , it exhibits no constraints.Comment: 11 pages,5 figures. Improved versio
Stress relaxation in F-actin solutions by severing
Networks of filamentous actin (F-actin) are important for the mechanics of
most animal cells. These cytoskeletal networks are highly dynamic, with a
variety of actin-associated proteins that control cross-linking, polymerization
and force generation in the cytoskeleton. Inspired by recent rheological
experiments on reconstituted solutions of dynamic actin filaments, we report a
theoretical model that describes stress relaxation behavior of these solutions
in the presence of severing proteins. We show that depending on the kinetic
rates of assembly, disassembly, and severing, one can observe both
length-dependent and length-independent relaxation behavior
Temporal and Spectral Correlations of Cyg X-1
Temporal and spectral properties of X-ray rapid variability of Cyg X-1 are
studied by an approach of correlation analysis in the time domain on different
time scales. The correlation coefficients between the total intensity in 2-60
keV and the hardness ratio of 13-60 keV to 2-6 keV band on the time scale of
about 1 ms are always negative in all states. For soft states, the correlation
coefficients are positive on all the time scales from about 0.01 s to 100 s,
which is significantly different with that for transition and low states.
Temporal structures in high energy band are narrower than that in low energy
band in quite a few cases. The delay of high energy photons relative to low
energy ones in the X-ray variations has also been revealed by the correlation
analysis. The implication of observed temporal and spectral characteristics to
the production region and mechanism of Cyg X-1 X-ray variations is discussed.Comment: 17 pages, 6 figures included, to appear in Ap
Optical and transport properties in doped two-leg ladder antiferromagnet
Within the t-J model, the optical and transport properties of the doped
two-leg ladder antiferromagnet are studied based on the fermion-spin theory. It
is shown that the optical and transport properties of the doped two-leg ladder
antiferromagnet are mainly governed by the holon scattering. The low energy
peak in the optical conductivity is located at a finite energy, while the
resistivity exhibits a crossover from the high temperature metallic-like
behavior to the low temperature insulating-like behavior, which are consistent
with the experiments.Comment: 13 pages, 5 figures, accepted for publication in Phys. Rev. B65
(2002) (April 15 issue
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