Anisotropic superconducting properties of aligned Sm0.95_{0.95}La0.05_{0.05}FeAsO0.85_{0.85}F0.15_{0.15} microcrystalline powder

The Sm$_{0.95}$La$_{0.05}$FeAsO$_{0.85}$F$_{0.15}$ compound is a quasi-2D layered superconductor with a superconducting transition temperature T$_c$ = 52 K. Due to the Fe spin-orbital related anisotropic exchange coupling (antiferromagnetic or ferromagnetic fluctuation), the tetragonal microcrystalline powder can be aligned at room temperature using the field-rotation method where the tetragonal $\it{ab}$-plane is parallel to the aligned magnetic field B$_{a}$ and $\it{c}$-axis along the rotation axis. Anisotropic superconducting properties with anisotropic diamagnetic ratio $\chi_{c}/\chi_{ab}\sim$ 2.4 + 0.6 was observed from low field susceptibility $\chi$(T) and magnetization M(B$_{a}$). The anisotropic low-field phase diagram with the variation of lower critical field gives a zero-temperature penetration depth $\lambda_{c}$(0) = 280 nm and $\lambda_{ab}$(0) = 120 nm. The magnetic fluctuation used for powder alignment at 300 K may be related with the pairing mechanism of superconductivity at lower temperature.Comment: 4 pages, 6 figure

A Sequential Circuit-Based IP Watermarking Algorithm for Multiple Scan Chains in Design-for-Test

In Very Large Scale Integrated Circuits (VLSI) design, the existing Design-for-Test(DFT) based watermarking techniques usually insert watermark through reordering scan cells, which causes large resource overhead, low security and coverage rate of watermark detection. A novel scheme was proposed to watermark multiple scan chains in DFT for solving the problems. The proposed scheme adopts DFT scan test model of VLSI design, and uses a Linear Feedback Shift Register (LFSR) for pseudo random test vector generation. All of the test vectors are shifted in scan input for the construction of multiple scan chains with minimum correlation. Specific registers in multiple scan chains will be changed by the watermark circuit for watermarking the design. The watermark can be effectively detected without interference with normal function of the circuit, even after the chip is packaged. The experimental results on several ISCAS benchmarks show that the proposed scheme has lower resource overhead, probability of coincidence and higher coverage rate of watermark detection by comparing with the existing methods

Petroleum generation timing and source in the Northern Longmen Shan Thrust Belt, Southwest China: Implications for multiple oil generation episodes and sources

The temporal evolution of hydrocarbons (∼500 million bbl) and its relationship to the orogenic events of the Longmen Shan thrust belt have been extensively debated. The hydrocarbons occur as solid bitumen, as dykes and/or coatings within/along faults/fractures, and as present-day oil seeps. Here, utilizing organic geochemistry, we demonstrate that all of the bitumen exhibit similar organo-geochemical characteristics, and were sourced from the upper Neoproterozoic–lower Cambrian Doushantuo and Qiongzhusi Formations. In contrast, the organic geochemistry of the present-day oil seeps are distinct from that of the bitumen, and suggest that the source is the Permian Dalong Formation. Bitumen Re-Os data indicate that the upper Neoproterozoic–lower Cambrian Doushantuo and Qiongzhusi Formations underwent two temporally distinct oil-generation events; initial oil generation occurred during the Late Cambrian/Early Ordovician prior to the Caledonian orogeny, and secondly during the Jurassic (∼165 Ma) coinciding with the Indosinian-Yanshan orogenies. In contrast, the Re-Os data of the present-day oil seeps are too similar to yield a meaningful age, although the source is considered to have undergone hydrocarbon maturation between the Triassic and Jurassic. The temporal hydrocarbon evolution in the Longmen Shan thrust belt also provides an understanding of the hydrocarbon evolution and future exploration of the adjacent petroliferous Sichuan Basin

Nuclear modification at sqrt{s_{NN}}=17.3 GeV, measured at NA49

Transverse momentum spectra up to 4.5 GeV/c were measured around midrapidity in Pb+Pb reactions at sqrt{s_{NN}}=17.3 GeV, for pi^{+/-}, p, pbar and K^{+/-}, by the NA49 experiment. The nuclear modification factors R_{AA}, R_{AA/pA} and R_{CP} were extracted and are compared to RHIC results at sqrt{s_{NN}}=200 GeV. The modification factor R_{AA} shows a rapid increase with transverse momentum in the covered region. The modification factor R_{CP} shows saturation well below unity in the pi^{+/-} channel. The extracted R_{CP} values follow the 200 GeV RHIC results closely in the available transverse momentum range for all particle species. For pi^{+/-} above 2.5 GeV/c transverse momentum, the measured suppression is smaller than that observed at RHIC. The nuclear modification factor R_{AA/pA} for pi^{+/-} stays well below unity.Comment: Proceedings of Quark Matter 2008 conferenc

Defective G protein activation of the cAMP pathway in rat kidney during genetic hypertension.

The development of hypertension in the spontaneously hypertensive rat (SHR) is associated with renal dysfunction and vasoconstriction. The kidneys of young SHRs exhibit exaggerated reactivity to angiotensin II (Ang-II) and attenuated responses to vasodilators that normally activate the cAMP signal to buffer hormone-induced vasoconstriction. The present study investigates the mechanism(s) responsible for this abnormality in activation of the cAMP second-messenger pathway in hypertensive animals. Renal vascular reactivity was assessed in 7-week-old anesthetized SHRs and normotensive Wistar-Kyoto rats. The animals were pretreated with indomethacin to block prostanoid production throughout an experiment. Ang-II was injected into the renal artery either alone or mixed with the vasodilator fenoldopam, a dopamine-receptor agonist. These two opposing vasoactive agents were administered before and during intrarenal infusion of NaF or cholera toxin, two activators of G proteins that stimulate cAMP production. The results show that Ang-II reduced renal blood flow by 45% in both strains. In Wistar-Kyoto rats, fenoldopam reduced the Ang-II-induced decrease in renal blood flow from -45% to -30%. This protective effect of fenoldopam was increased further during infusion of NaF or cholera toxin (-18% or -19% decrease in renal blood flow). In SHRs, fenoldopam failed to attenuate Ang II-mediated vasoconstriction (-45% vs. -44%). In contrast, fenoldopam effectively blunted the Ang-II-induced vasoconstriction when it was given concurrently with NaF or cholera toxin (-27 or -31% decrease in renal blood flow). These findings provide evidence for defective interaction between receptor coupling and activation of guanine nucleotide stimulatory factor proteins in the renal microcirculation of 7-week-old SHRs. Such a deficiency could play an important role in renal dysfunction associated with the development of genetic hypertension