Delocalized Quasiparticles in the Vortex State of an Overdoped High-Tc Superconductor Probed by 63Cu NMR

We report the spin Knight shift (K_s) and the nuclear spin-lattice relaxation rate (1/T_1) in the vortex state as a function of magnetic field (H) up to 28 T in the high-T_c superconductor TlSr_{2}CaCu_2O_{6.8} (T_c=68 K). At low temperatures well below T_{c}, both K_s and 1/T_1 measured around the middle point between two nearest vortices (saddle point) increase substantially with increasing field, which indicate that the quasiparticle states with an ungapped spectrum are extended outside the vortex cores in a d-wave superconductor. The density of states (DOS) around the saddle point is found to be \kappa N_0\sqrt{H/H_{c2}}, with \kappa=0.5\sim0.7 and N_0 being the normal-state DOS.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let

Ionization Source of a Minor-axis Cloud in the Outer Halo of M82

The M82 `cap' is a gas cloud at a projected radius of 11.6 kpc along the minor axis of this well known superwind source. The cap has been detected in optical line emission and X-ray emission and therefore provides an important probe of the wind energetics. In order to investigate the ionization source of the cap, we observed it with the Kyoto3DII Fabry-Perot instrument mounted on the Subaru Telescope. Deep continuum, Ha, [NII]6583/Ha, and [SII]6716,6731/Ha maps were obtained with sub-arcsecond resolution. The superior spatial resolution compared to earlier studies reveals a number of bright Ha emitting clouds within the cap. The emission line widths (< 100 km s^-1 FWHM) and line ratios in the newly identified knots are most reasonably explained by slow to moderate shocks velocities (v_shock = 40--80 km s^-1) driven by a fast wind into dense clouds. The momentum input from the M82 nuclear starburst region is enough to produce the observed shock. Consequently, earlier claims of photoionization by the central starburst are ruled out because they cannot explain the observed fluxes of the densest knots unless the UV escape fraction is very high (f_esc > 60%), i.e., an order of magnitude higher than observed in dwarf galaxies to date. Using these results, we discuss the evolutionary history of the M82 superwind. Future UV/X-ray surveys are expected to confirm that the temperature of the gas is consistent with our moderate shock model.Comment: 7 pages, 5 figures, 2 tables; Accepted for publication in Ap

Fluctuation of spastic location in patients with vasospastic angina: A quantitative angiographic study

Objectives.: This study sought to determine whether the location of coronary spastic activity may change over time in patients with persistent variant angina. Background.: Although electrocardiographic studies have provided indirect evidence to indicate that the location of ischemia may change in patients with variant angina, it has not been tested by quantitative angiography whether the location of vasospastic activity may change over time. Methods.: Paired ergonovine provocation tests and coronary angiography were performed at a mean (±SD) interval of 43 ± 13 months apart in patients with persistent symptoms of vasospastic angina in the absence of significant atherosclerosis. A total of 87 spastic and nonspastic segments of 87 major vessels in 29 patients were analyzed by quantitative angiography at baseline, after the administration of ergonovine and after isosorbide dinitrate at the initial and follow-up tests. Results.: In 13 patients (group 1), coronary spasm was observed in the same 16 coronary segments at both the initial and follow-up ergonovine provocation tests. In 16 patients (group 2), the following angiographic changes occurred between the initial and follow-up tests in 48 major vessels: Of the 23 segments that developed spasm at the initial test, 10 did not have spasm at the follow-up test; of the 25 vessels that did not demonstrate spasm on the initial test, 12 demonstrated spasm on the follow-up test (a new site of spasm). Thus, in 22 (46%) of 48 vessels, fluctuation of spastic location was observed at follow-up. Conclusions.: Quantitative coronary angiography and repeated ergonovine tests revealed that some patients with persistent vasospastic angina demonstrate fluctuation of vasospastic location, whereas others exhibit a fixed location of vasospasm. Vasospastic angina may not only be a transient disease restricted in location, but may also be a persistent and variable condition involving multiple vessels over many years

Endothelial Cell Junctional Adhesion Molecules: Role and Regulation of Expression in Inflammation

The authors are funded by the Wellcome Trust (Investigator Award to S. Nourshargh Ref: 098291/Z/12/Z). N. Reglero-Real is additionally supported by funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007–2013) under REA grant agreement no [608765]

Development of low-cost multi-wavelength imager system for studies of aurora and airglow

This paper introduces a new system that can monitor aurora and atmospheric airglow using a low-cost Watec monochromatic imager (WMI) equipped with a sensitive camera, a filter with high transmittance, and the non-telecentric optics. The WMI system with 486-nm, 558-nm, and 630-nm band-pass filters has observable luminosity of about ~200–4000 Rayleigh for 1.07-sec exposure time and about ~40–1200 Rayleigh for 4.27-sec exposure time, for example. It is demonstrated that the WMI system is capable of detecting 428-nm auroral intensities properly, through comparison with those measured with a collocated electron-multiplying charge-coupled device (EMCCD) imager system with narrower band-pass filter. The WMI system has two distinct advantages over the existing system: One makes it possible to reduce overall costs, and the other is that it enables the continuous observation even under twilight and moonlight conditions. Since 2013 a set of multi-wavelength WMIs has been operating in northern Scandinavia, Svalbard, and Antarctica to study meso- and large-scale aurora and airglow phenomena. Future development of the low-cost WMI system is expected to provide a great opportunity for constructing a global network for multi-wavelength aurora and airglow monitoring

Fermiological Interpretation of Superconductivity/Non-superconductivity of FeTe_{1-x}Se_{x} Thin Crystal Determined by Quantum Oscillation Measurement

We have successfully observed quantum oscillation (QO) for FeTe_{1-x}Se_{x}. QO measurements were performed using non-superconducting and superconducting thin crystals of FeTe_{0.65}Se_{0.35} fabricated by the scotch-tape method. We show that the Fermi surfaces (FS) of the non-superconducting crystal are in good agreement with the rigid band shift model based on electron doping by excess Fe while that of the superconducting crystal is in good agreement with the calculated FS with no shift. From the FS comparison of both crystals, we demonstrate the change of the cross-sectional area of the FS, suggesting that the suppression of the FS nesting with the vector Q_{s} = (\pi, \pi) due to excess Fe results in the disappearance of the superconductivity.Comment: 8 pages, 4 figure

Low-temperature Synthesis of FeTe0.5Se0.5 Polycrystals with a High Transport Critical Current Density

We have prepared high-quality polycrystalline FeTe0.5Se0.5 at temperature as low as 550{\deg}C. The transport critical current density evaluated by the current-voltage characteristics is over 700 A/cm2 at 4.2 K under zero field, which is several times larger than FeTe0.5Se0.5 superconducting wires. The critical current density estimated from magneto-optical images of flux penetration is also similar to this value. The upper critical field of the polycrystalline FeTe0.5Se0.5 at T = 0 K estimated by Werthamer-Helfand-Hohenberg theory is 585 kOe, which is comparable to that of single crystals. This study gives some insight into how to improve the performance of FeTe0.5Se0.5 superconducting wires.Comment: 12 pages, 6 figure