Field-free deterministic ultra fast creation of skyrmions by spin orbit torques

Magnetic skyrmions are currently the most promising option to realize current-driven magnetic shift registers. A variety of concepts to create skyrmions were proposed and demonstrated. However, none of the reported experiments show controlled creation of single skyrmions using integrated designs. Here, we demonstrate that skyrmions can be generated deterministically on subnanosecond timescales in magnetic racetracks at artificial or natural defects using spin orbit torque (SOT) pulses. The mechanism is largely similar to SOT-induced switching of uniformly magnetized elements, but due to the effect of the Dzyaloshinskii-Moriya interaction (DMI), external fields are not required. Our observations provide a simple and reliable means for skyrmion writing that can be readily integrated into racetrack devices

Climate change impacts on US agriculture and forestry: benefits of global climate stabilization

Increasing atmospheric carbon dioxide levels, higher temperatures, altered precipitation patterns, and other climate change impacts have already begun to affect US agriculture and forestry, with impacts expected to become more substantial in the future. There have been numerous studies of climate change impacts on agriculture or forestry, but relatively little research examining the long-term net impacts of a stabilization scenario relative to a case with unabated climate change. We provide an analysis of the potential benefits of global climate change mitigation for US agriculture and forestry through 2100, accounting for landowner decisions regarding land use, crop mix, and management practices. The analytic approach involves a combination of climate models, a crop process model (EPIC), a dynamic vegetation model used for forests (MC1), and an economic model of the US forestry and agricultural sector (FASOM-GHG). We find substantial impacts on productivity, commodity markets, and consumer and producer welfare for the stabilization scenario relative to unabated climate change, though the magnitude and direction of impacts vary across regions and commodities. Although there is variability in welfare impacts across climate simulations, we find positive net benefits from stabilization in all cases, with cumulative impacts ranging from $32.7 billion to$54.5 billion over the period 2015–2100. Our estimates contribute to the literature on potential benefits of GHG mitigation and can help inform policy decisions weighing alternative mitigation and adaptation actions.United States. Environmental Protection Agency. Climate Change Division (Contract EP-BPA-12-H-0023, Call Order EP-B13H-00143

Skyrmion Hall Effect Revealed by Direct Time-Resolved X-Ray Microscopy

Magnetic skyrmions are highly promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their finite topological charge leads to a predicted "skyrmion Hall effect", in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we present nanoscale pump-probe imaging that for the first time reveals the real-time dynamics of skyrmions driven by current-induced spin orbit torque (SOT). We find that skyrmions move at a well-defined angle {\Theta}_{SH} that can exceed 30{\deg} with respect to the current flow, but in contrast to theoretical expectations, {\Theta}_{SH} increases linearly with velocity up to at least 100 m/s. We explain our observation based on internal mode excitations in combination with a field-like SOT, showing that one must go beyond the usual rigid skyrmion description to unravel the dynamics.Comment: pdf document arxiv_v1.1. 24 pages (incl. 9 figures and supplementary information

Alumni Perceptions of the Training and Education Offered by the Georgia Law Enforcement Command College

The debate surrounding the need for and the value of higher education has continued among police executives since the early 20th century. The debate has resulted in a call for more integration of training and education in the professional development of police executives. One such program that has succeeded in the total integration of training and education is the Georgia Law Enforcement Command College at Columbus State University (Command College). The purpose of this research was to determine if graduates of the Command College (1998 -2010) believe they received quality education and training that positively impacted their job performance and provided the leadership skills needed for positions of greater authority and/or responsibility, while also determining if non-alumni agency heads believe that sending an officer or administrator to the Command College benefits the agency, sufficient to justify the expenditure of agency resources. Data gathered from the research provided both quantitative and qualitative responses for analysis, showing no statistical significant difference in the responses of the alumni and non-alumni agency heads surveyed. The data support the finding that alumni of the Command College perceive they have derived benefit from the education and training received and have a high level of satisfaction with the curriculum, program design, and the faculty of the Command College. The non-alumni agency heads provided similar responses, reporting a high degree of satisfaction with the results of the program. This satisfaction was widespread, diffuse, and not contained to any particular group or respondent characteristics.Prine, Rudy K., Committee Chair; Argyle, Nolan, Committee Member; Robinson, Deborah, Committee Member; Richards, Connie, Dean of College of Arts and Sciences; Hull, Karla, Interim Dean of Graduate School.Doctor of Public Administratio

Enhancements of Discretization Approaches for Non-Convex Mixed-Integer Quadratically Constraint Quadratic Programming

We study mixed-integer programming (MIP) relaxation techniques for the solution of non-convex mixed-integer quadratically constrained quadratic programs (MIQCQPs). We present two MIP relaxation methods for non-convex continuous variable products that enhance existing approaches. One is based on a separable reformulation, while the other extends the well-known MIP relaxation normalized multiparametric disaggregation technique (NMDT). In addition, we introduce a logarithmic MIP relaxation for univariate quadratic terms, called sawtooth relaxation, based on [4]. We combine the latter with the separable reformulation to derive MIP relaxations of MIQCQPs. We provide a comprehensive theoretical analysis of these techniques, and perform a broad computational study to demonstrate the effectiveness of the enhanced MIP relaxations in terms producing tight dual bounds for MIQCQP

Boric Acid and EDTA Combination Inhibits Growth of Candida albicans and Gardnerella vaginalis

Candida albicans and Gardnerella vaginalis are two common infectious organisms of the female urogenital tract. Single agent boric acid (BA) topical preparations have been a treatment for resistant gynecologic Candida and Gardnerella infections, but it is worth exploring combinations of inhibitors to determine if a more effective treatment may be developed. Our study aims to determine the efficacy of BA alone in comparison to the combination of BA and EDTA (BA + EDTA) by measuring organism growth, size, and morphology. Experiments used 12 clinical strains of Candida albicans and 7 strains of Gardnerella vaginalis. The organisms were grown in varying concentrations of BA and BA + EDTA media. Organisms were characterized by microscopy and flow cytometry. We report that the median effective dose of BA alone was greater than that of BA + EDTA in Candida strains. Microscopic evaluation revealed that exposure to BA and BA + EDTA decreased typical hyphal transformation of Candida, and cells appeared smaller in size. Flow cytometry forward scatter data of Candida grown in inhibitors revealed smaller cells than those grown in control conditions. Cell counts of organisms grown in inhibitors were also significantly decreased compared to control conditions. Incidental evaluation of autofluorescence revealed increased fluorescence of organisms exposed to inhibitors. Preliminary results of Candida strains grown in BA and BA + EDTA also revealed inhibition of virulence-associated protease activity. These data provide evidence supporting the potential use of a combination therapy in Candida and Gardnerella infections and prompt additional investigation into combination therapies with EDTA