Pressure-Induced Superconductivity in Sc to 74 GPa

Using a diamond anvil cell with nearly hydrostatic helium pressure medium we have significantly extended the superconducting phase diagram Tc(P) of Sc, the lightest of all transition metals. We find that superconductivity is induced in Sc under pressure, Tc increasing monotonically to 8.2 K at 74.2 GPa. The Tc(P) dependences of the trivalent d-electron metals Sc, Y, La, and Lu are compared and discussed within a simple s-d charge transfer framework.Comment: to be published in Phys. Rev. B (Brief Reports

GRID PRICING FOR FED CATTLE: AN EMPIRICAL ANALYSIS

Weekly grid premium and discount price date for fed cattle have been collected over a 3-year period. The grid price data are combined with carcass data (2590 South Dakota slaughter steers) to investigate the variability in the average weekly carcass premium is affected by changes in packer-determined grid premiums and discounts on a weekly basis. The three-stage recursive model is then estimated using an autoregressive procedure. The results of the empirical analysis indicated that among all grid premiums and discounts, it is the choice-select discount that plays the dominant role in determining weekly changes in the average weekly carcass premium (discount).slaughter cattle, grid pricing, average pricing, value-based-marketing, Marketing,

Heat transfer from the stagnation area of a heated cylinder at Re(D) = 140,000 affected by free-stream turbulence

This is the post-print version of the final paper published in International Journal of Heat and Mass Transfer. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V.The effect of free-stream grid-turbulence on the flow around and heat transfer from the stagnation region of a circular cylinder was studied using direct numerical simulations (DNS). Simulations with and without free-stream fluctuations were carried out at a Reynolds number of Re(D) = 140,000 (based on the inflow velocity and the cylinder diameter D), which is in the higher subcritical range. A splitter plate was introduced behind the cylinder to counteract the formation of a vortex street. To resolve the flow up to 746.5 million grid points were employed. Compared to the fully laminar simulation, the addition of Tu = 30% grid turbulence at the inflow plane was found to lead to an increase in heat transfer at the stagnation line of the cylinder of 66%. A very good agreement was obtained with the correlations of Dullenkopf and Mayle [K. Dullenkopf, R. Mayle, The effects of incident turbulence and moving wakes on laminar heat transfer in gas turbines, ASME J. Turbomach. 116 (1994) 23–28; K. Dullenkopf, R. Mayle, An account of free-stream-turbulence length scale on laminar heat transfer, ASME J. Turbomach. 117 (1995) 401–406].The German Research Foundatio

On the renormalized scalar density in quenched QCD

We present a non-perturbative determination of the renormalization factor Z_S of the scalar density in quenched QCD with overlap fermions. Results are obtained at four values of the lattice spacing. By combining Z_S with results for the low-energy constant Sigma we are able to compute the renormalization group invariant scalar condensate in the continuum limit with a total accuracy of 7%, excluding dynamical quark effects. Our result translates to Sigma_msbar(2 GeV)=(285+/-9 MeV)^3 if the scale is set by the kaon decay constant. We have also performed scaling studies of the pseudoscalar decay constant and the vector mass. Our results indicate that quantities computed using overlap quarks exhibit excellent scaling behaviour, with small residual lattice artifacts.Comment: 15 pages, 7 figure

Testing a Model of Minority Identity Achievement, Identity Affirmation and Psychological Well-Being among Ethnic Minority and Sexual Minority Individuals

How is social identity related to psychological well-being among minority individuals? Drawing on developmental models of identity formation (e.g., Erikson, 1968) and on Social Identity Theory (Tajfel & Turner, 1979), we tested a conceptual model examining links between two key aspects of social identity and psychological well-being. We proposed that the association between identity achievement (exploring and understanding the meaning of one\u27s identity) and psychological well-being is mediated by identity affirmation (developing positive feelings and a sense of belonging to one\u27s social group). Across three studies, including ethnic minority high school students (Study 1), ethnic minority college students (Study 2) and lesbian and gay male adults (Study 3), we found strong support for the model. Results suggest that the process of exploring and understanding one\u27s minority identity can serve as an important basis for developing positive feelings toward and an enhanced sense of attachment to the group, which can in turn confer psychological benefits for minority individuals. Implications and directions for future research are discussed

An analysis of experts' ratings of ergonomic stress

Experts in the field of industrial ergonomics are frequently called upon to visit workplaces in order to evaluate and rate ergonomic stressors which may cause fatigue, discomfort, or injury. The objective of this study was to evaluate the extent of agreement among experts' perceptions of four categories of ergonomic stress: materials handling (e.g., lifting), upper extremity activities, posture, and energy expenditure.A panel of five experts observed ten jobs in manufacturing and warehouse facilities. A three-point scale (1 = insignificant stress, 2 = moderate stress, 3 = high stress) was used to rate the jobs in each of the four stress categories. In addition, lifting stresses on each job were analyzed using methods described in the NIOSH Work Practices Guide for Manual Lifting. The resulting data were analyzed to determine the level of expert consensus and the level of agreement with the NIOSH results.In general, there was a high level of consensus among the experts. Perfect agreement (identical ratings by all five experts) was obtained for 30 percent of the experts' scores; while consensus agreement (identical ratings by three or more experts) was obtained for 87.5 percent of the scores. In general, the experts' perceptions agreed with the NIOSH ratings of lifting stress. On a few jobs, however, the expert panel considered lifting stresses to be greater than predicted by the NIOSH ratings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27200/1/0000203.pd

Chiral Lagrangian Parameters for Scalar and Pseudoscalar Mesons

The results of a high-statistics study of scalar and pseudoscalar meson propagators in quenched lattice QCD are presented. For two values of lattice spacing, $\beta=5.7$ ($a \approx .18$ fm) and 5.9 ($a \approx .12$ fm), we probe the light quark mass region using clover improved Wilson fermions with the MQA pole-shifting ansatz to treat the exceptional configuration problem. The quenched chiral loop parameters $m_0$ and $\alpha_{\Phi}$ are determined from a study of the pseudoscalar hairpin correlator. From a global fit to the meson correlators, estimates are obtained for the relevant chiral Lagrangian parameters, including the Leutwyler parameters $L_5$ and $L_8$. Using the parameters obtained from the singlet and nonsinglet pseudoscalar correlators, the quenched chiral loop effect in the nonsinglet scalar meson correlator is studied. By removing this QCL effect from the lattice correlator, we obtain the mass and decay constant of the ground state scalar, isovector meson $a_0$.Comment: 36 pages, 12 figures, LaTe

Assembling the puzzle of superconducting elements: A Review

Superconductivity in the simple elements is of both technological relevance and fundamental scientific interest in the investigation of superconductivity phenomena. Recent advances in the instrumentation of physics under pressure have enabled the observation of superconductivity in many elements not previously known to superconduct, and at steadily increasing temperatures. This article offers a review of the state of the art in the superconductivity of elements, highlighting underlying correlations and general trends.Comment: Review, 10 pages, 11 figures, 97 references; to appear in Superc. Sci. Techno

Effect of pressure on the Raman modes of antimony

The effect of pressure on the zone-center optical phonon modes of antimony in the A7 structure has been investigated by Raman spectroscopy. The A_g and E_g frequencies exhibit a pronounced softening with increasing pressure, the effect being related to a gradual suppression of the Peierls-like distortion of the A7 phase relative to a cubic primitive lattice. Also, both Raman modes broaden significantly under pressure. Spectra taken at low temperature indicate that the broadening is at least partly caused by phonon-phonon interactions. We also report results of ab initio frozen-phonon calculations of the A_g and E_g mode frequencies. Presence of strong anharmonicity is clearly apparent in calculated total energy versus atom displacement relations. Pronounced nonlinearities in the force versus displacement relations are observed. Structural instabilities of the Sb-A7 phase are briefly addressed in the Appendix.Comment: 10 pages, 8 figure

Tunable Electron Multibunch Production in Plasma Wakefield Accelerators

Synchronized, independently tunable and focused $\mu$J-class laser pulses are used to release multiple electron populations via photo-ionization inside an electron-beam driven plasma wave. By varying the laser foci in the laboratory frame and the position of the underdense photocathodes in the co-moving frame, the delays between the produced bunches and their energies are adjusted. The resulting multibunches have ultra-high quality and brightness, allowing for hitherto impossible bunch configurations such as spatially overlapping bunch populations with strictly separated energies, which opens up a new regime for light sources such as free-electron-lasers