Tail States in Disordered Superconductors with Magnetic Impurities: the Unitarity Limit

When subject to a weak magnetic impurity distribution, the order parameter and quasi-particle energy gap of a weakly disordered bulk s-wave superconductor are suppressed. In the Born scattering limit, recent investigations have shown that `optimal fluctuations' of the random impurity potential can lead to the nucleation of `domains' of localised states within the gap region predicted by the conventional Abrikosov-Gor'kov mean-field theory, rendering the superconducting system gapless at any finite impurity concentration. By implementing a field theoretic scheme tailored to the weakly disordered system, the aim of the present paper is to extend this analysis to the consideration of magnetic impurities in the unitarity scattering limit. This investigation reveals that the qualitative behaviour is maintained while the density of states exhibits a rich structure.Comment: 18 pages AMSLaTeX (with LaTeX2e), 6 eps figure

Itinerant ferromagnetism in an atomic Fermi gas: Influence of population imbalance

We investigate ferromagnetic ordering in an itinerant ultracold atomic Fermi gas with repulsive interactions and population imbalance. In a spatially uniform system, we show that at zero temperature the transition to the itinerant magnetic phase transforms from first to second order with increasing population imbalance. Drawing on these results, we elucidate the phases present in a trapped geometry, finding three characteristic types of behavior with changing population imbalance. Finally, we outline the potential experimental implications of the findings.Comment: 10 pages, 4 figures, typos added, references adde

Transcytosis in MDCK cells: identification of glycoproteins transported bidirectionally between both plasma membrane domains.

MDCK cells display fluid-phase transcytosis in both directions across the cell. Transcytosis of cell surface molecules was estimated by electron microscopic analysis of streptavidin-gold-labeled frozen sections of biotinylated cells. Within 3 h, approximately 10% of the surface molecules, biotinylated on the starting membrane domain, were detected on the opposite surface domain irrespective of the direction of transcytosis. This suggests that the transcytosis rates for surface molecules are equal in both directions across the cell as shown previously for fluid-phase markers

Chemical composition of zircons from the Cornubian Batholith of SW England and comparison with zircons from other European Variscan rare-metal granites

This is the author accepted manuscript. The final version is available from the Mineralogical Society via the DOI in this record.Zircon from 14 representative granite samples of the late-Variscan Cornubian Batholith in SW England was analyzed for W, P, As, Nb, Ta, Si, Ti, Zr, Hf, Th, U, Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, Al, Sc, Bi, Mn, Fe, Ca, Pb, Cu, S, and F using EPMA. Zircons from the biotite and tourmaline granites are poor in minor and trace elements, usually containing 1.0–1.5 wt% HfO2, <0.5 wt% UO2 and P2O5, <0.25 wt% Y2O3, <0.2 wt% Sc203 and Bi2O3, and <0.1 wt% ThO2. Zircon from topaz granites from the St. Austell Pluton, Meldon Aplite and Megiliggar Rocks are slightly enriched in Hf (up to 4 wt% HfO2), U (1– 3.5 wt% UO2), and Sc (0.5–1 wt% Sc2O3). Scarce metamictized zircon grains are somewhat enriched in Al, Ca, Fe, and Mn. The decrease of the zircon Zr/Hf ratio, a reliable magma fractionation index, from 110-60 in the biotite granites to 30-10 in the most evolved topaz granites (Meldon Aplite and Megiliggar Rocks), supports a comagmatic origin of the biotite and topaz granites via long fractionation of common peraluminous crustal magma. In comparison with other European rare-metal provinces, the overall contents of trace elements in Cornubian zircons are low and the Zr/Hf- and U/Th-ratios show lower degrees of fractionation of the parental melt.This contribution was supported by the Czech Science Foundation, project No. GA14-13600S and RVO 67985831. Bernard Bingen and one anonymous member of the Editorial Board are thanked for careful review and inspiring comments

JWalk: a tool for lazy, systematic testing of java classes by design introspection and user interaction

Popular software testing tools, such as JUnit, allow frequent retesting of modified code; yet the manually created test scripts are often seriously incomplete. A unit-testing tool called JWalk has therefore been developed to address the need for systematic unit testing within the context of agile methods. The tool operates directly on the compiled code for Java classes and uses a new lazy method for inducing the changing design of a class on the fly. This is achieved partly through introspection, using Java’s reflection capability, and partly through interaction with the user, constructing and saving test oracles on the fly. Predictive rules reduce the number of oracle values that must be confirmed by the tester. Without human intervention, JWalk performs bounded exhaustive exploration of the class’s method protocols and may be directed to explore the space of algebraic constructions, or the intended design state-space of the tested class. With some human interaction, JWalk performs up to the equivalent of fully automated state-based testing, from a specification that was acquired incrementally

Field Theory of Mesoscopic Fluctuations in Superconductor/Normal-Metal Systems

Thermodynamic and transport properties of normal disordered conductors are strongly influenced by the proximity of a superconductor. A cooperation between mesoscopic coherence and Andreev scattering of particles from the superconductor generates new types of interference phenomena. We introduce a field theoretic approach capable of exploring both averaged properties and mesoscopic fluctuations of superconductor/normal-metal systems. As an example the method is applied to the study of the level statistics of a SNS-junction.Comment: 4 pages, REVTEX, two eps-figures included; submitted to JETP letter

Nocodazole-Dependent Transport, and Brefeldin A-Sensitive Processing and Sorting, of Newly Synthesized Membrane-Proteins in Cultured Neurons

The envelope glycoproteins of Semliki Forest virus (SFV), Vesicular Stomatitis virus (VSV), and Influenza Fowl Plague virus (FPV) are vectorially targeted in neurons to the plasma membrane of dendrites (SFV and VSV) and axons (FPV), To gain insight into the mechanisms responsible for such polarized delivery we have examined the effects on neurons of nocodazole and brefeldin A (BFA), which are known to cause microtubule depolymerization and disassembly of the Golgi apparatus, respectively, Nocodazole treatment blocked transport of all viral glycoproteins to both axons and dendrites, BFA treatment induced disruption of the Golgi complex, including the trans-Golgi network (TGN), and tubulation of endosomes, However, the delivery of the SFV and FPV glycoproteins to the cell surface was not affected significantly by BFA, although processing and sorting were altered as revealed by surface biotinylation and immunofluorescence microscopy of fixed nonpermeabilized cells, These results demonstrate the involvement of microtubules in axonal and dendritic transport of integral membrane glycoproteins, and the existence of a BFA-sensitive component in the sorting but not in the transport machinery

Particle dynamics of a cartoon dune

The spatio-temporal evolution of a downsized model for a desert dune is observed experimentally in a narrow water flow channel. A particle tracking method reveals that the migration speed of the model dune is one order of magnitude smaller than that of individual grains. In particular, the erosion rate consists of comparable contributions from creeping (low energy) and saltating (high energy) particles. The saltation flow rate is slightly larger, whereas the number of saltating particles is one order of magnitude lower than that of the creeping ones. The velocity field of the saltating particles is comparable to the velocity field of the driving fluid. It can be observed that the spatial profile of the shear stress reaches its maximum value upstream of the crest, while its minimum lies at the downstream foot of the dune. The particle tracking method reveals that the deposition of entrained particles occurs primarily in the region between these two extrema of the shear stress. Moreover, it is demonstrated that the initial triangular heap evolves to a steady state with constant mass, shape, velocity, and packing fraction after one turnover time has elapsed. Within that time the mean distance between particles initially in contact reaches a value of approximately one quarter of the dune basis length

Distribution of "level velocities" in quasi 1D disordered or chaotic systems with localization

The explicit analytical expression for the distribution function of parametric derivatives of energy levels ("level velocities") with respect to a random change of scattering potential is derived for the chaotic quantum systems belonging to the quasi 1D universality class (quantum kicked rotator, "domino" billiard, disordered wire, etc.).Comment: 11 pages, REVTEX 3.