Spin diffusion at finite electric and magnetic fields

Spin transport properties at finite electric and magnetic fields are studied by using the generalized semiclassical Boltzmann equation. It is found that the spin diffusion equation for non-equilibrium spin density and spin currents involves a number of length scales that explicitly depend on the electric and magnetic fields. The set of macroscopic equations can be used to address a broad range of the spin transport problems in magnetic multilayers as well as in semiconductor heterostructure. A specific example of spin injection into semiconductors at arbitrary electric and magnetic fields is illustrated

Light-cone QCD Sum Rules for the Λ\Lambda Baryon Electromagnetic Form Factors and its magnetic moment

We present the light-cone QCD sum rules up to twist 6 for the electromagnetic form factors of the $\Lambda$ baryon. To estimate the magnetic moment of the baryon, the magnetic form factor is fitted by the dipole formula. The numerical value of our estimation is $\mu_\Lambda=-(0.64\pm0.04)\mu_N$, which is in accordance with the experimental data and the existing theoretical results. We find that it is twist 4 but not the leading twist distribution amplitudes that dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.

High Pressure Thermoelasticity of Body-centered Cubic Tantalum

We have investigated the thermoelasticity of body-centered cubic (bcc) tantalum from first principles by using the linearized augmented plane wave (LAPW) and mixed--basis pseudopotential methods for pressures up to 400 GPa and temperatures up to 10000 K. Electronic excitation contributions to the free energy were included from the band structures, and phonon contributions were included using the particle-in-a-cell (PIC) model. The computed elastic constants agree well with available ultrasonic and diamond anvil cell data at low pressures, and shock data at high pressures. The shear modulus $c_{44}$ and the anisotropy change behavior with increasing pressure around 150 GPa because of an electronic topological transition. We find that the main contribution of temperature to the elastic constants is from the thermal expansivity. The PIC model in conjunction with fast self-consistent techniques is shown to be a tractable approach to studying thermoelasticity.Comment: To be appear in Physical Review

The Designers Leap: Boundary Jumping to foster interdisciplinarity between Textile Design and Science

Creative thinking is an instinctive problem-solving process for designers however, designers alone cannot solve real-world problems. Collaboration between higher education and industry, and across design and science disciplines can create new paradigms of research to address societal and economic challenges. This paper argues from the perspective of fashion and textile designers, for design to be at the heart of the collaborative research process and advocates for co-design, speculative-design and scenario design to be considered as valid methodologies to foster interdisciplinarity. Perspectives on interdisciplinary partnerships across academic disciplines and with industry are typified by two very different reflections of collaborative projects between fashion designers, textile designers, scientists and industrial partners. The paper identifies commonalities and differences between scientists and designers, with particular relevance to textiles, in a bid to understand how they may collaborate more effectively in the context of interdisciplinary work, and the paper further identifies factors needed for establishing common enablers for engaging in co-design. This is an under-explored field and highlights the changing role of the designer, and as such is of value to researchers in textiles, fashion and product design

The first decade of web-based sports injury surveillance: Descriptive epidemiology of injuries in US high school girls' lacrosse (2008-2009 through 2013-2014) and National Collegiate Athletic Association women's lacrosse (2004-2005 through 2013-2014)

Context: The advent of Web-based sports injury surveillance via programs such as the High School Reporting Information Online (HS RIO) system and the National Collegiate Athletic Association Injury Surveillance Program (NCAA-ISP) has aided the acquisition of girls' and women's lacrosse injury data. Objective: To describe the epidemiology of injuries sustained in high school girls' lacrosse in the 2008-2009 through 2013-2014 academic years and collegiate women's lacrosse in the 2004-2005 through 2013-2014-academic years using Web-based sports injury surveillance. Design: Descriptive epidemiology study. Setting: Online injury surveillance from high school girls' (annual average ¼ 55) and collegiate women's (annual average ¼ 19) lacrosse teams. Patients or Other Participants: Female lacrosse players who participated in practices or competitions during the 2008-2009 through 2013-2014 academic years for high school or the 2004-2005 through 2013-2014 academic years for college. Main Outcome Measure(s): Athletic trainers collected time-loss injury (24 hours) and exposure data. We calculated injury rates per 1000 athlete-exposures (AEs), injury rate ratios (IRRs) with 95% confidence intervals (CIs), and injury proportions by body site and diagnosis. Results: High school RIO documented 700 time-loss injuries during 481 687 AEs; the NCAA-ISP documented 1027 time-loss injuries during 287 856 AEs. The total injury rate during 2008-2009 through 2013-2014 was higher in college than in high school (2.55 versus 1.45/1000 AEs; IRR ¼ 1.75; 95% CI ¼ 1.54, 1.99). Most injuries occurred during competitions in high school (51.1%) and practices in college (63.8%). Rates were higher during competitions compared with practices in high school (IRR ¼ 2.32; 95% CI ¼ 2.00, 2.69) and college (IRR ¼ 2.38; 95% CI ¼ 2.09, 2.70). Concussion was the most common diagnosis among all high school and most collegiate player positions, and the main mechanism of contact was with a playing apparatus (eg, stick, ball). Ligament sprains were also common (HS RIO practices ¼ 22.2%, competitions ¼ 30.3%; NCAA-ISP practices ¼ 25.5%, competitions ¼ 30.9%). Conclusions: Rates of injury were higher in college versus high school female lacrosse players and in competitions versus practices. Injury-prevention strategies are essential to decrease the incidence and severity of concussions and ligament sprains

On the history and future of soil organic phosphorus research:a critique across three generations

Soil organic phosphorus has broad agronomic and ecological significance, but remains a neglected topic of research. This opinion paper reflects a collaborative discussion between three generations of scientists who have collectively studied soil organic phosphorus for almost 50 years. We discuss personal reflections on our involvement in the field, opinions about progress and promising opportunities for future research. We debate an apparent overemphasis on analytical methodology at the expense of broader questions, and whether this has stifled progress in recent decades. We reiterate the urgent need to understand organic phosphorus cycling in the environment to address fundamental questions about phosphate supply, crop nutrition, water quality and ecosystem ecology. We also contend that we must encourage and integrate the study of organic phosphorus across all scales, from molecular chemistry to global cycling. Our discussion among three generations of researchers shows the value of a long-term perspective, emphasizes the changing nature of this field of research, and reinforces the importance of continuing to be curious about the dynamics of organic phosphorus in the environment

The first decade of web-based sports injury surveillance: Descriptive epidemiology of injuries in US high school boys' lacrosse (2008-2009 through 2013-2014) and National Collegiate Athletic Association men's lacrosse (2004-2005 through 2013-2014)

Context: The advent of Web-based sports injury surveillance via programs such as the High School Reporting Information Online system and the National Collegiate Athletic Association Injury Surveillance Program has aided the acquisition of boys' and men's lacrosse injury data. Objective: To describe the epidemiology of injuries sustained in high school boys' lacrosse in the 2008-2009 through 2013-2014 academic years and collegiate men's lacrosse in the 2004-2005 through 2013-2014 academic years using Web-based sports injury surveillance. Design: Descriptive epidemiology study. Setting: Online injury surveillance from lacrosse teams of high school boys (annual average ¼ 55) and collegiate men (annual average ¼ 14). Patients or Other Participants: Boys' and men's lacrosse players who participated in practices and competitions during the 2008-2009 through 2013-2014 academic years in high school or the 2004-2005 through 2013-2014 academic years in college. Main Outcome Measure(s): Athletic trainers collected time-loss (24 hours) injury and exposure data. Injury rates per 1000 athlete-exposures (AEs), injury rate ratios (IRRs) with 95% confidence intervals (CIs), and injury proportions by body site and diagnosis were calculated. Results: High School Reporting Information Online documented 1407 time-loss injuries during 662 960 AEs. The National Collegiate Athletic Association Injury Surveillance Program documented 1882 time-loss injuries during 390 029 AEs. The total injury rate from 2008-2009 through 2013-2014 was higher in college than in high school (3.77 versus 2.12/1000 AEs; IRR ¼ 1.78; 95% CI ¼ 1.63, 1.94). Most injuries occurred during competitions in high school (61.4%) and practices in college (61.4%). Injury rates were higher in competitions compared with practices in high school (IRR ¼ 3.59; 95% CI ¼ 3.23, 4.00) and college (IRR ¼ 3.38; 95% CI ¼ 3.08, 3.71). Lower limb injuries, muscle strains, and ligament sprains were common at both levels. Concussion was the most frequent competition diagnosis for all high school player positions. Conclusions: Rates of time-loss injury were higher in college versus high school and in competitions versus practices. Attention to preventing common lower leg injuries and concussions, especially at the high school level, is essential to decrease their incidence and severity

Nucleon Charge and Magnetization Densities from Sachs Form Factors

Relativistic prescriptions relating Sachs form factors to nucleon charge and magnetization densities are used to fit recent data for both the proton and the neutron. The analysis uses expansions in complete radial bases to minimize model dependence and to estimate the uncertainties in radial densities due to limitation of the range of momentum transfer. We find that the charge distribution for the proton is significantly broad than its magnetization density and that the magnetization density is slightly broader for the neutron than the proton. The neutron charge form factor is consistent with the Galster parametrization over the available range of Q^2, but relativistic inversion produces a softer radial density. Discrete ambiguities in the inversion method are analyzed in detail. The method of Mitra and Kumari ensures compatibility with pQCD and is most useful for extrapolating form factors to large Q^2.Comment: To appear in Phys. Rev. C. Two new figures and accompanying text have been added and several discussions have been clarified with no significant changes to the conclusions. Now contains 47 pages including 21 figures and 2 table

A Solvable Regime of Disorder and Interactions in Ballistic Nanostructures, Part I: Consequences for Coulomb Blockade

We provide a framework for analyzing the problem of interacting electrons in a ballistic quantum dot with chaotic boundary conditions within an energy $E_T$ (the Thouless energy) of the Fermi energy. Within this window we show that the interactions can be characterized by Landau Fermi liquid parameters. When $g$, the dimensionless conductance of the dot, is large, we find that the disordered interacting problem can be solved in a saddle-point approximation which becomes exact as $g\to\infty$ (as in a large-N theory). The infinite $g$ theory shows a transition to a strong-coupling phase characterized by the same order parameter as in the Pomeranchuk transition in clean systems (a spontaneous interaction-induced Fermi surface distortion), but smeared and pinned by disorder. At finite $g$, the two phases and critical point evolve into three regimes in the $u_m-1/g$ plane -- weak- and strong-coupling regimes separated by crossover lines from a quantum-critical regime controlled by the quantum critical point. In the strong-coupling and quantum-critical regions, the quasiparticle acquires a width of the same order as the level spacing $\Delta$ within a few $\Delta$'s of the Fermi energy due to coupling to collective excitations. In the strong coupling regime if $m$ is odd, the dot will (if isolated) cross over from the orthogonal to unitary ensemble for an exponentially small external flux, or will (if strongly coupled to leads) break time-reversal symmetry spontaneously.Comment: 33 pages, 14 figures. Very minor changes. We have clarified that we are treating charge-channel instabilities in spinful systems, leaving spin-channel instabilities for future work. No substantive results are change

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc