Effect of Magnetic Impurity Correlations on Josephson Tunneling

The ordering trend of magnetic impurities at low temperature results in the frustration of the pair-breaking effect and induces a ``recovery'' of superconducting properties. We show that this effect manifests itself in the deviation of the Josephson current amplitude from the values obtained within the Ambegaokar-Baratoff and the Abrikosov-Gor'kov models. We consider both weak and strong-coupling cases. The theory is applied to describe the experimental data obtained for the low-$T_c$ superconductor SmRh$_4$B$_4$. We further predict a ``recovery'' effect of the Josephson current in high-temperature superconductors.Comment: 7 pages, 4 figures. Accepted for publication in Physica

Children and Megadisasters: Lessons Learned in the New Millennium

Hurricane Katrina is America’s most recent encounter with a megadisaster. But what made it a megadisaster instead of just another category 3 hurricane of the type that seasonally exists in the Gulf of Mexico? Katrina was not the largest or strongest hurricane to strike the United States mainland in the recent past, but its effects were devastating and wide reaching beyond our wildest nightmares, far beyond those of Hurricane Andrew (1992), a category 5 hurricane that scoured much of Florida and the Gulf Coast. Hurricane Katrina’s track directly targeted gaping vulnerabilities in infrastructure and society, and set in motion a series of events that culminated in the deaths of nearly 2000 people, resulted in hundreds of missing individuals, and caused a potential economic impact of up to $150 billion. The disruption of people’s lives was immeasurable, as was the impact on the long-term physical and mental health of the victims, which continues today. Katrina also led to a substantial decline in the confidence that the public has in its government to provide essential services during a disaster. Children are among the most susceptible members of a community when catastrophes such as these strike because of their dependent nature as well as their physiologic and psychological vulnerability. Children affected by Katrina were no exception. Persistent critical gaps exist in the ability to prepare for and respond to the needs of the youngest victims. These were clearly exposed as children endured an at times ineffectual disaster response followed by a stressful recovery that is still ongoing. An analysis of the issues that faced children during this event and some others from the recent past may help society reduce the impact of such disasters on children in the future. This article focuses on a few of the major shortfalls in the care of children that have become especially apparent in the last few years: Facilitating evacuation; Providing shelter; Caring for those with special medical needs; Addressing mental health needs

Anomalous magnetic field dependence of the thermodynamic transition line in the isotropic superconductor (K,Ba)Bi03

Thermodynamic (specific heat, reversible magnetization, tunneling spectroscopy) and transport measurements have been performed on high quality (K,Ba)BiO$_3$ single crystals. The temperature dependence of the magnetic field $H_{Cp}$ corresponding to the onset of the specific heat anomaly presents a clear positive curvature. $H_{Cp}$ is significantly smaller than the field $H_\Delta$ for which the superconducting gap vanishes but is closely related to the irreversibility line deduced from transport data. Moreover, the temperature dependence of the reversible magnetization present a strong deviation from the Ginzburg--Landau theory emphasazing the peculiar nature of the superconducting transition in this material.Comment: 4 pages, 4 figures, 28 reference