51 research outputs found
Critical fluctuation conductivity in layered superconductors in strong electric field
The paraconductivity, originating from critical superconducting
order-parameter fluctuations in the vicinity of the critical temperature in a
layered superconductor is calculated in the frame of the self-consistent
Hartree approximation, for an arbitrarily strong electric field and zero
magnetic field. The paraconductivity diverges less steep towards the critical
temperature in the Hartree approximation than in the Gaussian one and it shows
a distinctly enhanced variation with the electric field. Our results indicate
that high electric fields can be effectively used to suppress order-parameter
fluctuations in high-temperature superconductors.Comment: 11 pages, 2 figures, to be published in Phys. Rev.
Anomalous dimensions and phase transitions in superconductors
The anomalous scaling in the Ginzburg-Landau model for the superconducting
phase transition is studied. It is argued that the negative sign of the
exponent is a consequence of a special singular behavior in momentum space. The
negative sign of comes from the divergence of the critical correlation
function at finite distances. This behavior implies the existence of a Lifshitz
point in the phase diagram. The anomalous scaling of the vector potential is
also discussed. It is shown that the anomalous dimension of the vector
potential has important consequences for the critical dynamics in
superconductors. The frequency-dependent conductivity is shown to obey the
scaling . The prediction is
obtained from existing Monte Carlo data.Comment: RevTex, 20 pages, no figures; small changes; version accepted in PR
Dynamical Scaling: the Two-Dimensional XY Model Following a Quench
To sensitively test scaling in the 2D XY model quenched from
high-temperatures into the ordered phase, we study the difference between
measured correlations and the (scaling) results of a Gaussian-closure
approximation. We also directly compare various length-scales. All of our
results are consistent with dynamical scaling and an asymptotic growth law , though with a time-scale that depends on the
length-scale in question. We then reconstruct correlations from the
minimal-energy configuration consistent with the vortex positions, and find
them significantly different from the ``natural'' correlations --- though both
scale with . This indicates that both topological (vortex) and
non-topological (``spin-wave'') contributions to correlations are relevant
arbitrarily late after the quench. We also present a consistent definition of
dynamical scaling applicable more generally, and emphasize how to generalize
our approach to other quenched systems where dynamical scaling is in question.
Our approach directly applies to planar liquid-crystal systems.Comment: 10 pages, 10 figure
Archaeological signatures of landscape and settlement change on the Isle of Harris
Between 2004 and 2011, a programme of archaeological investigation by the University of Birmingham on the Isle of Harris, a distinctive island forming part of the Western Isles of Scotland, has allowed the archaeological remains of this enigmatic place to be further characterised and understood. Despite intensive archaeological interest in the archipelago for a number of decades, the Isle of Harris has been overlooked and only now are we beginning to identify the archaeological resource and make comparisons to the wealth of published data from islands such as the Uists, Barra and Lewis. This paper highlights some generic overall patterns of archaeological signatures on the Isle which has been identified through a range of archaeological methods including field walking, intrusive excavation, aerial reconnaissance, geophysical and topographical survey, and documentary research. Several key case studies will be introduced including upland shieling complexes and mulitperiod settlement sites on the west coast machair systems. The purpose of the paper is not to present a gazetteer of the results of the work to date, but to highlight some of the key findings with a view to demonstrating that the Isle of Harris is directly comparable with the archaeologically rich landscapes of the other islands
Percutaneous Nephroscopy: A Review of the Physical Properties, Suitability and Cost of the Instruments
The Use of Exercise Testing in Children to Evaluate Abnormalities of Pacemaker Function not Apparent at Rest
Characterization of Phosphorus Sources in Rural Watersheds
Correct identification of P sources in rural watersheds is critical for the development of cost-effective measures to combat agriculturally-driven eutrophication. The chemical composition of various storm runoff types (field surface runoff, field drain outfalls, roads, farmyards, and septic tanks) and the receiving streams in three micro (>1 mg Lâ1) than surface and subsurface runoff from cultivated land and pasture (0.02â3.6 mg TP Lâ1, mean 50% vs. <50%) of P in dissolved forms. It is concluded that P sources associated with the functioning of rural communities (impervious surfaces, detergents, and wastewater) may be more ecologically relevant than those associated with agriculture and should be better quantified and controlled to avoid localized eutrophication impacts
Diapause influenced oviposition behavior and physical egg hatch cues of Aedes atropalpus
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