158,590 research outputs found
New physical principles of contact thermoelectric cooling
We suggest a new approach to the theory of the contact thermoelectric cooling
(Peltier effect). The metal-metal, metal-n-type semiconductor, metal-p-type
semiconductor, p-n junction contacts are analyzed. Both degenerate and
non-degenerate electron and hole gases are considered. The role of
recombination in the contact cooling effect is discussed by the first time.Comment: 8 pages, 8 figures, revtex
Contact-eutectic-lens fabrication technique
Method enables use of crystal or semiconductor materials with selective spectral-response characteristics (ultraviolet, visible, or infrared wavelengths) in fabrication of contact lenses, reading glasses, and photographic processing equipment
Spin-correlation functions in ultracold paired atomic-fermion systems: sum rules, self-consistent approximations, and mean fields
The spin response functions measured in multi-component fermion gases by
means of rf transitions between hyperfine states are strongly constrained by
the symmetry of the interatomic interactions. Such constraints are reflected in
the spin f-sum rule that the response functions must obey. In particular, only
if the effective interactions are not fully invariant in SU(2) spin space, are
the response functions sensitive to mean field and pairing effects. We
demonstrate, via a self-consistent calculation of the spin-spin correlation
function within the framework of Hartree-Fock-BCS theory, how one can derive a
correlation function explicitly obeying the f-sum rule. By contrast, simple
one-loop approximations to the spin response functions do not satisfy the sum
rule. As we show, the emergence of a second peak at higher frequency in the rf
spectrum, as observed in a recent experiment in trapped , can be
understood as the contribution from the paired fermions, with a shift of the
peak from the normal particle response proportional to the square of the BCS
pairing gap.Comment: 7 pages, 1 figure, content adde
Multifractal analysis of complex networks
Complex networks have recently attracted much attention in diverse areas of
science and technology. Many networks such as the WWW and biological networks
are known to display spatial heterogeneity which can be characterized by their
fractal dimensions. Multifractal analysis is a useful way to systematically
describe the spatial heterogeneity of both theoretical and experimental fractal
patterns. In this paper, we introduce a new box covering algorithm for
multifractal analysis of complex networks. This algorithm is used to calculate
the generalized fractal dimensions of some theoretical networks, namely
scale-free networks, small world networks and random networks, and one kind of
real networks, namely protein-protein interaction networks of different
species. Our numerical results indicate the existence of multifractality in
scale-free networks and protein-protein interaction networks, while the
multifractal behavior is not clear-cut for small world networks and random
networks. The possible variation of due to changes in the parameters of
the theoretical network models is also discussed.Comment: 18 pages, 7 figures, 4 table
On Wilson Criterion
U(1) gauge theory with the Villain action on a cubic lattice approximation of
three- and four-dimensional torus is considered. The naturally chosen
correlation functions converge to the correlation functions of the R-gauge
electrodynamics on three- and four-dimensional torus as the lattice spacing
approaches zero only for the special scaling. This special scaling depends on a
choice of a correlation function system. Another scalings give the degenerate
continuum limits. The Wilson criterion for the confinement is ambiguous. The
asymptotics of the smeared Wilson loop integral for the large loop perimeters
is defined by the density of the loop smearing over a torus which is
transversal to the loop plane. When the initial torus radius tends to infinity
the correlation functions converge to the correlation functions of the R-gauge
Euclidean electrodynamics.Comment: latex, 6 page
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