Paramagnetic reentrant effect in high purity mesoscopic AgNb proximity structures

We discuss the magnetic response of clean Ag coated Nb proximity cylinders in the temperature range 150 \mu K < T < 9 K. In the mesoscopic temperature regime, the normal metal-superconductor system shows the yet unexplained paramagnetic reentrant effect, discovered some years ago [P. Visani, A. C. Mota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990)], superimposing on full Meissner screening. The logarithmic slope of the reentrant paramagnetic susceptibility chi_para(T) \propto \exp(-L/\xi_N) is limited by the condition \xi_N=n L, with \xi_N=\hbar v_F/2 \pi k_B T, the thermal coherence length and n=1,2,4. In wires with perimeters L=72 \mu m and L=130 \mu m, we observe integer multiples n=1,2,4. At the lowest temperatures, \chi_para compensates the diamagnetic susceptibility of the \textit{whole} AgNb structure.Comment: 4 pages, 4 figures (color

La responsabilidad social de las empresas y los códigos de conducta: ¿Nuevos retos o viejos debates?

En este artículo, se analiza en profundidad el concepto de la responsabilidad social de las empresas, a través del estudio de organismos que promueven y apoyan esta estrategia. El artículo presenta un balance en torno a este tema y trata de las consecuencias que la RSE tiene sobre los instrumentos nacionales e internacionales (sectoriales e interprofesionales) y los normativos (derechos laborales y derechos sociales), así como sobre el futuro de esos derechos legislativos y contractuales y sobre el contenido de las políticas sociales. Luego de los dos primeros apartados, en los que se aborda este tema y una de sus firmas de representación (los códigos de conducta), se expone la situación actual y finalmente, se concluye con algunas lineas de acción y varias recomendaciones

Paramagnetic Reentrance Effect in NS Proximity Cylinders

A scenario for the unusual paramagnetic reentrance behavior at ultra-low temperatures in Nb-Ag, Nb-Au, and Nb-Cu cylinders is presented. For the diamagnetic response down to temperatures of the order 15 mK, the standard theory (quasi-classical approximation) for superconductors appears to work very well, assuming that Ag, Au, and Cu remain in the normal state except for the proximity-induced superconductivity. Here it is proposed that these noble metals may become p-wave superconductors with a transition temperature of order 10 mK. Below this temperature, p-wave triplet superconductivity emerges around the periphery of the cylinder. The diamagnetic current flowing in the periphery is compensated by a quantized paramagnetic current in the opposite direction, thus providing a simple explanation for the observed increase in the susceptibility at ultra-low temperatures.Comment: RevTex, 8 pages with 1 eps figur

Conservation of statistical results under the reduction of pair-contact interactions to solvation interactions

We show that the hydrophobicity of sequences is the leading term in Miyazawa-Jernigan interactions. Being the source of additive (solvation) terms in pair-contact interactions, they were used to reduce the energy parameters while resulting in a clear vector manipulation of energy. The reduced (additive) potential performs considerably successful in predicting the statistical properties of arbitrary structures. The evaluated designabilities of the structures by both models are highly correlated. Suggesting geometrically non-degenerate vectors (structures) as protein-like structures, the additive model is a powerful tool for protein design. Moreover, a crossing point in the log-linear diagram of designability-ranking shows that about 1/e of the structures have designabilities above the average, independent on the used model.Comment: 17 pages and 10 figure

Rough Surface Effect on Meissner Diamagnetism in Normal-layer of N-S Proximity-Contact System

Rough surface effect on the Meissner diamagnetic current in the normal layer of proximity contact N-S bi-layer is investigated in the clean limit. The diamagnetic current and the screening length are calculated by use of quasi-classical Green's function. We show that the surface roughness has a sizable effect, even when a normal layer width is large compared with the coherence length $\xi =v_{\rm F}/\pi T_{\rm c}$. The effect is as large as that of the impurity scattering and also as that of the finite reflection at the N-S interface.Comment: 12 pages, 3 figures. To be published in J. Phys. Soc. Jpn. Vol.71-

Detection of hyperbilirubinaemia in jaundiced full-term neonates by eye or by bilirubinometer?

The aim of this study was to compare predictions of hyperbilirubinaemia by eye, performed by trained physicians and nurses, with predictions obtained using two commercial bilirubinometers. Jaundice was assessed in 92 white and 48 non-white healthy full-term neonates using three non-invasive methods and by total serum bilirubin as the reference method. Clinical assessment of cephalocaudal progression of jaundice was carried out independently by a physician and by nurses. Simultaneously, the Minolta Airshields JM-102 was applied on the sternum, the BiliCheck on both the forehead and the sternum, and finally, serum bilirubin concentrations were determined. The Minolta JM-102 showed the best performance with r2=0.90, an intraclass correlation coefficient (ICC) of 0.93, and a 95% confidence interval (CI) of ±4units (approx. 56µmol/l). The BiliCheck performed slightly better on the forehead than over the sternum with r2=0.90, an ICC of 0.88, and a CI of ±62µmol/l. Assessment of jaundice by eye was least accurate with r2=0.74, an ICC of 0.67, and a CI of ±1.5 zones (corresponding to ±75µmol/l). Skin pigmentation and ambient light both adversely affected non-invasive bilirubin estimation. Conclusion:All three non-invasive methods are well suited for estimation of serum bilirubin but show large confidence intervals. In healthy term newborns, hyperbilirubinaemia (>250µmol/l) can be safely ruled out by eye if jaundice does not reach the abdomen or the extremities (Kramer zones 1 and 2), with <22 units (<230µmol/l) for the Minolta JM-102, or with a cut-off of 190µmol/l for the BiliCheck. If these respective thresholds are exceeded, serum bilirubin concentrations should be measure

Proximity-induced screening and its magnetic breakdown in mesoscopic hybrid structures

We derive a general microscopic expression for the non-linear diamagnetic current in a clean superconductor-insulator-normal metal structure with an arbitrary interface transmission. In the absence of electron-electron interactions in the normal metal the diamagnetic response increases monotonously with decreasing temperature showing no sign of paramagnetic reentrance down to T=0. We also analyze the magnetic breakdown of proximity induced Meissner screening. We demonstrate that the magnetic breakdown field should be strongly suppressed in the limit of small interface transmissions while the linear diamagnetic current does not depend on the transmission of the insulating barrier at low enough temperatures.Comment: 7 pages, 2 figure

Magnetic breakdown in a normal-metal - superconductor proximity sandwich

We study the magnetic response of a clean normal-metal slab of finite thickness in proximity with a bulk superconductor. We determine its free energy and identify two (meta-)stable states, a diamagnetic one where the applied field is effectively screened, and a second state, where the field penetrates the normal-metal layer. We present a complete characterization of the first order transition between the two states which occurs at the breakdown field, including its spinodals, the jump in the magnetization, and the latent heat. The bistable regime terminates at a critical temperature above which the sharp transition is replaced by a continuous cross-over. We compare the theory with experiments on normal-superconducting cylinders.Comment: 7 pages Revtex, 3 Postscript figures, needs psfig.te