Ginzburg-Landau theory for the time-dependent phase field in a two-dimensional d-wave superconductor

We derive a finite temperature time-dependent effective theory for the phase $\theta$ of the pairing field, which is appropriate for a 2D conducting electron system with non-retarded d-wave attraction. As for s-wave pairing the effective action contains terms with Landau damping, but their structure appears to be different from the s-wave case due to the fact that the Landau damping is determined by the quasiparticle group velocity $v_g$, which for the d-wave pairing does not have the same direction as the non-interacting Fermi velocity $v_F$. We show that for the d-wave pairing the Landau terms have a linear low temperature dependence and in contrast to the s-wave case are important for all finite temperatures.Comment: 4 pages, LaTeX; paper presented at New^3SC-3, Honolulu, Hawaii, USA, 2001. To be published in Physica

Polypropylene Mesh Predicts Mesh/Suture Exposure After Sacrocolpopexy Independent of Known Risk Factors

Objective(s) The aim of this study was to determine if ultralightweight polypropylene mesh reduced the risk of mesh/suture exposure after sacrocolpopexy compared with heavier-weighted polypropylene. Methods Bivariate and multivariate analyses were used to interpret data from 133 cases and 261 control subjects to evaluate independent predictors of mesh/suture exposure after sacrocolpopexy from 2003 to 2013. Results Multivariate logistic regression revealed that prior surgery for incontinence (odds ratio [OR], 2.87; 95% confidence interval [CI], 1.19–6.96), porcine acellular cross-linked collagen matrix with medium-weight polypropylene mesh (OR, 4.95; 95% CI, 1.70–14.42), other polypropylene mesh (OR, 6.73; 95% CI, 1.12–40.63), nonabsorbable braided suture for vaginal mesh attachment (OR, 4.52; 95% CI, 1.53–15.37), and immediate perioperative complications (OR, 3.64; 95% CI, 1.53–13.37) were independent risk factors for mesh/suture exposure. After multivariate analysis, ultralightweight polypropylene mesh was no longer associated with decreased rates of mesh/suture exposure after controlling for known risk factors identified during bivariate analysis (P = 0.423). Conclusions Both mesh choice and suture selection remained independent predictors of mesh/suture exposure, with heavier meshes increasing and monofilament suture decreasing rates of mesh/suture exposure. Based on this study, surgeons may consider use of delayed-absorbable, monofilament suture over nonabsorbable braided suture for attachment of vaginal mesh to reduce the risk of mesh/suture exposure when using mesh

Criticality experiments with planar arrays of three-liter bottles containing plutonium nitrate solution

The objective of these experiments was to provide benchmark data to validate calculational codes used in critically safety assessments of plant configurations. Arrays containing up to as many as sixteen three-liter bottles filled with plutonium nitrate were used in the experiments. A split-table device was used in the final assembly of the arrays. Ths planar arrays were reflected with close fitting plexiglas on each side and on the bottom but not the top surface. The experiments addressed a number of factors effecting criticality: the critical air gap between bottles in an array of fixed number of bottles, the number of bottles required for criticality if the bottles were touching, and the effect on critical array spacing and critical bottle number due to the insertion of an hydrogeneous substance into the air gap between bottles. Each bottle contained about 2.4l of Pu(NO{sub 3}){sub 4} solution at a Pu concentration of 105g Pu/l, with the {sup 240}Pu content being 2.9 wt% at a free acid molarity H{sup +} of 5.1. After the initial series of experiments were performed with bottles separated by air gaps, plexiglas shells of varying thicknesses were placed around each bottle to investigate how moderation between bottles affects both the number of bottles required for criticality and the critical spacing between each bottle. The minimum of bottles required for criticality was found to be 10.9 bottles, occurring for a square array with bottles in contact. As the bottles were spaced apart, the critical number increased. For sixteen bottles in a square array, the critical separation between surfaces in both x and y direction was 0.96 cm. The addition of plexiglas around each bottle decreased the critical bottle number, compared to those separated in air, but the critical bottle number, even with interstitial plastic in place was always greater than 10.9 bottles. The most reactive configuration was a tightly packed array of bottles with no intervening material

Field-induced thermal metal-to-insulator transition in underdoped LSCO

The transport of heat and charge in cuprates was measured in undoped and heavily-underdoped single crystal La_{2-x}Sr_xCuO_{4+delta} (LSCO). In underdoped LSCO, the thermal conductivity is found to decrease with increasing magnetic field in the T --> 0 limit, in striking contrast to the increase observed in all superconductors, including cuprates at higher doping. The suppression of superconductivity with magnetic field shows that a novel thermal metal-to-insulator transition occurs upon going from the superconducting state to the field-induced normal state.Comment: 2 pages, 2 figures, submitted to M2S-Rio 2003 Proceeding

Radiation-Induced Magnetoresistance Oscillations in a 2D Electron Gas

Recent measurements of a 2D electron gas subjected to microwave radiation reveal a magnetoresistance with an oscillatory dependence on the ratio of radiation frequency to cyclotron frequency. We perform a diagrammatic calculation and find radiation-induced resistivity oscillations with the correct period and phase. Results are explained via a simple picture of current induced by photo-excited disorder-scattered electrons. The oscillations increase with radiation intensity, easily exceeding the dark resistivity and resulting in negative-resistivity minima. At high intensity, we identify additional features, likely due to multi-photon processes, which have yet to be observed experimentally.Comment: 5 pages, 3 figures; final version as published in Phys Rev Let

Age, habitat, and yearly variation in the diet of a generalist insectivore, the Southwestern Willow Flycatcher

The article presents a study which examines the age, habitat, and yearly variation in the diet of a generalist insectivore, the southwestern Willow Flycatcher at Roosevelt Lake in central Arizona. It focuses on the five prey categories which were accounted for 70% of the proportional abundance in flycatcher diet, including Hymenoptera, Diptera, Cicadellidae, Coleoptera, and Formicide. It states that there were no detected differences in diet between sexes of adults, but adults and nestling samples differed, with higher proportions of Hymenoptera in adult samples and more Diptera in nestling samples. It discusses the comparison between flycatcher diet in habitat patches dominated by native cottonwood and willow, exotic salt cedar, or a mix of the three species

Microwave conductivity of a d-wave superconductor disordered by extended impurities: a real-space renormalization group approach

Using a real-space renormalization group (RSRG) technique, we compute the microwave conductivity of a d-wave superconductor disordered by extended impurities. To do this, we invoke a semiclassical approximation which naturally accesses the Andreev bound states localized near each impurity. Tunneling corrections (which are captured using the RSRG) lead to a delocalization of these quasiparticles and an associated contribution to the microwave conductivity.Comment: 8 pages, 4 figures. 2 figures added to previous versio

Theory of Thermal Conductivity in High-Tc Superconductors below Tc: Comparison between Hole-Doped and Electron-Doped Systems

In hole-doped high-Tc superconductors, thermal conductivity increases drastically just below Tc, which has been considered as a hallmark of a nodal gap. In contrast, such a coherence peak in thermal conductivity is not visible in electron-doped compounds, which may indicate a full-gap state such as a (d+is)-wave state. To settle this problem, we study the thermal conductivity in the Hubbard model using the fluctuation-exchange (FLEX) approximation, which predicts that the nodal d-wave state is realized in both hole-doped and electron-doped compounds. The contrasting behavior of thermal conductivity in both compounds originates from the differences in the hot/cold spot structure. In general, a prominent coherence peak in thermal conductivity appears in line-node superconductors only when the cold spot exists on the nodal line.Comment: 5 pages, to be published in J. Phys. Soc. Jpn. Vol.76 No.