A possible solution of the grain boundary problem for applications of high-Tc superconductors

It is shown that the critical current density of high-Tc wires can be greatly enhanced by using a threefold approach, which consists of grain alignment, doping, and optimization of the grain architecture. According to model calculations, current densities of 4x10^6 A/cm2 can be achieved for an average grain alignment of 10 degree at 77K. Based on this approach, a road to competitive high-Tc cables is proposed.Comment: 3 pages, 5 figure

Design and realization of a sputter deposition system for the \textit{in situ-} and \textit{in operando-}use in polarized neutron reflectometry experiments

We report on the realization of a sputter deposition system for the in situ- and in operando-use in polarized neutron reflectometry experiments. Starting with the scientific requirements, which define the general design considerations, the external limitations and boundaries imposed by the available space at a neutron beamline and by the neutron and vacuum compatibility of the used materials, are assessed. The relevant aspects are then accounted for in the realization of our highly mobile deposition system, which was designed with a focus on a quick and simple installation and removability at the beamline. Apart from the general design, the in-vacuum components, the auxiliary equipment and the remote control via a computer, as well as relevant safety aspects are presented in detail.Comment: Submitted for publication in Nuclear Inst. and Methods in Physics Research, A. (1st revised version

Extremely Small Energy Gap in the Quasi-One-Dimensional Conducting Chain Compound SrNbO3.41_{3.41}

Resistivity, optical, and angle-resolved photoemission experiments reveal unusual one-dimensional electronic properties of highly anisotropic SrNbO$_{3.41}$. Along the conducting chain direction we find an extremely small energy gap of only a few meV at the Fermi level. A discussion in terms of typical 1D instabilities (Peierls, Mott-Hubbard) shows that neither seems to provide a satisfactory explanation for the unique properties of SrNbO$_{3.41}$.Comment: 4 pages, 3 figure

From uncertainty to reward: BOLD characteristics differentiate signaling pathways

<p>Abstract</p> <p>Background</p> <p>Reward value and uncertainty are represented by dopamine neurons in monkeys by distinct phasic and tonic firing rates. Knowledge about the underlying differential dopaminergic pathways is crucial for a better understanding of dopamine-related processes. Using functional magnetic resonance blood-oxygen level dependent (BOLD) imaging we analyzed brain activation in 15 healthy, male subjects performing a gambling task, upon expectation of potential monetary rewards at different reward values and levels of uncertainty.</p> <p>Results</p> <p>Consistent with previous studies, ventral striatal activation was related to both reward magnitudes and values. Activation in medial and lateral orbitofrontal brain areas was best predicted by reward uncertainty. Moreover, late BOLD responses relative to trial onset were due to expectation of different reward values and likely to represent phasic dopaminergic signaling. Early BOLD responses were due to different levels of reward uncertainty and likely to represent tonic dopaminergic signals.</p> <p>Conclusions</p> <p>We conclude that differential dopaminergic signaling as revealed in animal studies is not only represented locally by involvement of distinct brain regions but also by distinct BOLD signal characteristics.</p

Molecular analysis of plasmalemma vesicle-associated protein and its biological functions in the mammalian vascular endothelium

Plasmalemma vesicle-associated protein (PLVAP), a cationic, endothelial-specific, integral membrane glycoprotein is exclusively localized to stomatal and fenestral diaphragms of caveolae, transendothelial channels and fenestrae. Fenestral and stomatal diaphragms are known to consist of radial fibrils which extend from the peripheral rim of the celllular pore and meet in a central mesh. They act as a permselective barrier, regulating permeability by allowing the passage of water and solutes but inhibiting the transfer of macromolecules across the endothelial barrier. It has been hypothesized that the radial fibrils of diaphragms are built by PLVAP dimers. To learn about the molecular and biological functions of PLVAP, we generated mutant mice that are deficient in PLVAP and characterized their phenotype. Depending on the respective genetic background, the deletion of Plvap caused either perinatal lethality associated with severe subcutaneous hemorrhages, edema, defects in vascular integrity, and cardiac malformations, or early postnatal death at around 4 weeks of age. Electron microscopy showed the complete absence of diaphragms in caveolae, transendothelial channels, and fenestrae in Plvap-deficient animals. In addition, the lack of PLVAP caused a substantial reduction in the number of fenestrae in fenestrated vascular beds such as the choroid, the peritubular capillaries of the kidney interstitium, or the pancreas. The reduced number of fenestrae caused a restricted transendothelial passage of water and solutes, an effect which correlated with a retardation of postnatal growth. Intriguingly, the deletion of PLVAP also caused lack of fenestrae in non-diaphragmed liver sinusoidal cells. Consequently, permeability and the passage of chylomicron remnants and other lipoproteins, such as HDL and LDL, was reduced between the lumen of liver sinusoids and the hepatocytes, a scenario that caused hyperlipoproteinemia and resulted in liver injury. In conclusion, PLVAP was identified as an essential structural component of stomatal and fenestral diaphragms which are completely absent in endothelial cells of Plvap-deficient animals. Furthermore, PLVAP/diaphragms are required for the formation of fenestrations, since the loss of diaphragms due to the absence of PLVAP results in a dramatic reduction of fenestrations in both fenestrated and discontinuous vascular beds. This effect is accompanied by major physiological and metabolic changes such as in the liver where fenestrations in sinusoidal endothelial cells are critically required for the passage of lipoproteins