643 research outputs found

    Anomalous double peak structure in Nb/Ni superconductor/ferromagnet tunneling DOS

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    We have experimentally investigated the density of states (DOS) in Nb/Ni (S/F) bilayers as a function of Ni thickness, dFd_F. Our thinnest samples show the usual DOS peak at ±Δ0\pm\Delta_0, whereas intermediate-thickness samples have an anomalous ``double-peak'' structure. For thicker samples (dF≄3.5d_F \geq 3.5 nm), we see an ``inverted'' DOS which has previously only been reported in superconductor/weak-ferromagnet structures. We analyze the data using the self-consistent non-linear Usadel equation and find that we are able to quantitatively fit the features at ±Δ0\pm\Delta_0 if we include a large amount of spin-orbit scattering in the model. Interestingly, we are unable to reproduce the sub-gap structure through the addition of any parameter(s). Therefore, the observed anomalous sub-gap structure represents new physics beyond that contained in the present Usadel theory.Comment: 4 pages, 3 figure

    Ethical Aspects of Chesapeake Bay Use

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    https://scholarworks.wm.edu/vimsbooks/1000/thumbnail.jp

    Isolation, production, purification, assay and characterization of fibrinolytic enzymes (Nattokinase, Streptokinase and Urokinase) from bacterial sources

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    Nattokinase, Streptokinase and Urokinase are novel fibrinolytic enzymes which are isolated from Bacillus subtilis, ÎČ-haemolytic Streptococci and urine sample. The fibrinolytic enzyme Nattokinase, Streptokinase and Urokinase was purified from supernatant of Bacillus subtilis, ÎČ-haemolytic Streptococci and recombinant E.coli containing short fragment genomic DNA of Pseudomonas sp. Culture broth and showed thermophilic, hydrophilic, and strong fibrinolytic activity. The optimum temperature and pH of Nattokinase, Streptokinase and Urokinase were 37-55°C and 9, 27-37°C and 7 and 55°C and 9, respectively. The molecular weight of Nattokinase, Streptokinase and Urokinase was approximately 28 kDa, 47 kDa and 34 kDa, respectively, as determined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis. The caseinolytic activity of Nattokinase, Streptokinase and Urokinase were 576.73 U, 467.73 U and 785.73 U, respectively, while fibrinolytic activity achieved by fibrin plate method were 10 U, 5 U and 15 U, respectively.Key words: Anticoagulant activity, submerge fermentation, fibrinolytic enzyme activity, protein fraction precipitation, casein, serum and plasminogen plate technique, enzyme thermodynamics, haemolytic activity, enzyme screening, expression system, zymography, Edman degradation

    Kinetics of Co-oxidation of Ethylene Glycol & Propan-2-ol by Acid Bromate

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    211-21

    Optimizing global health experiences in emergency medicine residency programs: A consensus statement from the Council of Emergency Medicine Residency Directors 2011 Academic Assembly global health specialty track

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    BACKGROUND: An increasing number of emergency medicine (EM) residency training programs have residents interested in participating in clinical rotations in other countries. However, the policies that each individual training program applies to this process are different. To our knowledge, little has been done in the standardization of these experiences to help EM residency programs with the evaluation, administration and implementation of a successful global health clinical elective experience. The objective of this project was to assess the current status of EM global health electives at residency training programs and to establish recommendations from educators in EM on the best methodology to implement successful global health electives. METHODS: During the 2011 Council of Emergency Medicine Residency Directors (CORD) Academic Assembly, participants met to address this issue in a mediated discussion session and working group. Session participants examined data previously obtained via the CORD online listserve, discussed best practices in global health applications, evaluations and partnerships, and explored possible solutions to some of the challenges. In addition a survey was sent to CORD members prior to the 2011 Academic Assembly to evaluate the resources and processes for EM residents’ global experiences. RESULTS: Recommendations included creating a global health working group within the organization, optimizing a clearinghouse of elective opportunities for residents and standardizing elective application materials, site evaluations and resident assessment/feedback methods. The survey showed that 71.4% of respondents have global health partnerships and electives. However, only 36.7% of programs require pre-departure training, and only 20% have formal competency requirements for these global health electives. CONCLUSIONS: A large number of EM training programs have global health experiences available, but these electives and the trainees may benefit from additional institutional support and formalized structure

    High carrier mobility in transparent Ba1-xLaxSnO3 crystals with a wide band gap

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    We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility even though its band gap is large. The Hall mobility of Ba0.98La0.02SnO3 crystals with the n-type carrier concentration of \sim 8-10\times10 19 cm-3 is found to be \sim 103 cm2 V-1s-1 at room temperature, and the precise measurement of the band gap \Delta of a BaSnO3 crystal shows \Delta=4.05 eV, which is significantly larger than those of other transparent conductive oxides. The high mobility with a wide band gap indicates that (Ba,La)SnO3 is a promising candidate for transparent conductor applications and also epitaxial all-perovskite multilayer devices

    X-ray diffraction measurements of the c-axis Debye-Waller factors of YBa2Cu3O7 and HgBa2CaCu2O6

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    We report the first application of x-rays to the measurement of the temperature dependent Bragg peak intensities to obtain Debye-Waller factors on high-temperature superconductors. Intensities of (0,0,l) peaks of YBa2Cu3O7 and HgBa2CaCu2O6 thin films are measured to obtain the c-axis Debye-Waller factors. While lattice constant and some Debye-Waller factor measurements on high Tc superconductors show anomalies at the transition temperature, our measurements by x-ray diffraction show a smooth transition of the c-axis Debye-Waller factors through Tc_c. This suggests that the dynamic displacements of the heavy elements along the c-axis direction in these compounds do not have anomalies at Tc. This method in combination with measurements by other techniques will give more details concerning dynamics of the lattice.Comment: 4 pages, 2 figures. To be published in Physical Review B (Brief Report

    Origin of the Thermoreversible fcc-bcc Transition in Block Copolymer Solutions

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    The thermoreversible fcc-bcc transition in concentrated block copolymer micellar solutions is shown to be driven by decreases in the aggregation number as the solvent penetrates the core, leading to a softer intermicelle potential. Small-angle neutron scattering measurements in a dilute solution are used to quantify the temperature-dependent micellar characteristics. The observed phase boundary is in excellent agreement with recent simulations of highly branched star polymers.This work was supported primarily by the MRSEC Program of the National Science Foundation under Grant No. DMR-0212302, and also in part by the Brain Korea 21 Program endorsed by the Korean Ministry of Education. We acknowledge helpful discussions with C. N. Likos

    Stellar Lyman-alpha Emission Lines in the Hubble Space Telescope Archive: Intrinsic Line Fluxes and Absorption from the Heliosphere and Astrospheres

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    We search the Hubble Space Telescope (HST) archive for previously unanalyzed observations of stellar H I Lyman-alpha emission lines, our primary purpose being to look for new detections of Lyman-alpha absorption from the outer heliosphere, and to also search for analogous absorption from the astrospheres surrounding the observed stars. The astrospheric absorption is of particular interest because it can be used to study solar-like stellar winds that are otherwise undetectable. We find and analyze 33 HST Lyman-alpha spectra in the archive. All the spectra were taken with the E140M grating of the Space Telescope Imaging Spectrograph (STIS) instrument on board HST. The HST/STIS spectra yield 4 new detections of heliospheric absorption (70 Oph, Xi Boo, 61 Vir, and HD 165185) and 7 new detections of astrospheric absorption (EV Lac, 70 Oph, Xi Boo, 61 Vir, Delta Eri, HD 128987, and DK UMa), doubling the previous number of heliospheric and astrospheric detections. When combined with previous results, 10 of 17 lines of sight within 10 pc yield detections of astrospheric absorption. This high detection fraction implies that most of the ISM within 10 pc must be at least partially neutral, since the presence of H I within the ISM surrounding the observed star is necessary for an astrospheric detection. In contrast, the detection percentage is only 9.7% (3 out of 31) for stars beyond 10 pc. Our Lyman-alpha analyses provide measurements of ISM H I and D I column densities for all 33 lines of sight, and we discuss some implications of these results. Finally, we measure chromospheric Lyman-alpha fluxes from the observed stars. We use these fluxes to determine how Lyman-alpha flux correlates with coronal X-ray and chromospheric Mg II emission, and we also study how Lyman-alpha emission depends on stellar rotation.Comment: 56 pages, 15 figures; AASTEX v5.0 plus EPSF extensions in mkfig.sty; accepted by ApJ
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