Current-Induced Resonant Motion of a Magnetic Vortex Core: Effect of Nonadiabatic Spin Torque

The current-induced resonant excitation of a magnetic vortex core is investigated by means of analytical and micromagnetic calculations. We find that the radius and the phase shift of the resonant motion are not correctly described by the analytical equations because of the dynamic distortion of a vortex core. In contrast, the initial tilting angle of a vortex core is free from the distortion and determined by the nonadiabaticity of the spin torque. It is insensitive to experimentally uncontrollable current-induced in-plane Oersted field. We propose that a time-resolved imaging of the very initial trajectory of a core is essential to experimentally estimate the nonadiabaticity.Comment: 4 pages, 4 figure

Current-induced domain wall motion in a nanowire with perpendicular magnetic anisotropy

We study theoretically the current-induced magnetic domain wall motion in a metallic nanowire with perpendicular magnetic anisotropy. The anisotropy can reduce the critical current density of the domain wall motion. We explain the reduction mechanism and identify the maximal reduction conditions. This result facilitates both fundamental studies and device applications of the current- induced domain wall motion

Seasonal Gradient Patterns of Polycyclic Aromatic Hydrocarbons and Particulate Matter Concentrations near a Highway

Close proximity to roadways has been associated with higher exposure to traffic-related air pollutants. However, analyses of the effects of season and meteorological parameters on horizontal gradient patterns of traffic-generated air pollutants still need to be elucidated. Our objectives were to: (1) determine effects of season on horizontal gradient patterns of polycyclic aromatic hydrocarbons (PAHs), total suspended particles (TSP), and PM2.5 near a heavily trafficked highway; and (2) examine the effect of day-of-the-week variations (weekday versus weekend) associated with traffic counts on measured airborne-contaminant levels. PAHs (Σ8PAHs [MW 228–278]; gas + particulate), TSP and PM2.5 were monitored at nominal distances (50, 100, and 150 m) from the New Jersey Turnpike every 6 days for periods of 24 h, between September 2007 and September 2008. Seasonal variations in the horizontal gradient patterns of Σ8PAHs were observed. In the summer, Σ8PAHs declined significantly between 50–100 m from the highway (23% decrease), but not between the furthermost distances (100–150 m). An inverse pattern was observed in the winter: Σ8PAHs declined between 100–150 m (26% decrease), but not between the closest distances. Σ8PAHs and TSP, but not PM2.5, concentrations measured on weekends were 12–37% lower than those on weekdays, respectively, corresponding to lower diesel traffic volume. This study suggests that people living in the close proximity to highways may be exposed to varying levels of Σ8PAHs, TSP, and PM2.5 depending on distance to highway, season, and day-of-the-week variations

Prediction of Giant Spin Motive Force due to Rashba Spin-Orbit Coupling

Magnetization dynamics in a ferromagnet can induce a spin-dependent electric field through spin motive force. Spin current generated by the spin-dependent electric field can in turn modify the magnetization dynamics through spin-transfer torque. While this feedback effect is usually weak and thus ignored, we predict that in Rashba spin-orbit coupling systems with large Rashba parameter $\alpha_{\rm R}$, the coupling generates the spin-dependent electric field [\pm(\alpha_{\rm R}m_e/e\hbar) (\vhat{z}\times \partial \vec{m}/\partial t)], which can be large enough to modify the magnetization dynamics significantly. This effect should be relevant for device applications based on ultrathin magnetic layers with strong Rashba spin-orbit coupling.Comment: 4+ pages, 2 figure

Quantitative Screening of Cervical Cancers for Low-Resource Settings: Pilot Study of Smartphone-Based Endoscopic Visual Inspection After Acetic Acid Using Machine Learning Techniques

Background: Approximately 90% of global cervical cancer (CC) is mostly found in low- and middle-income countries. In most cases, CC can be detected early through routine screening programs, including a cytology-based test. However, it is logistically difficult to offer this program in low-resource settings due to limited resources and infrastructure, and few trained experts. A visual inspection following the application of acetic acid (VIA) has been widely promoted and is routinely recommended as a viable form of CC screening in resource-constrained countries. Digital images of the cervix have been acquired during VIA procedure with better quality assurance and visualization, leading to higher diagnostic accuracy and reduction of the variability of detection rate. However, a colposcope is bulky, expensive, electricity-dependent, and needs routine maintenance, and to confirm the grade of abnormality through its images, a specialist must be present. Recently, smartphone-based imaging systems have made a significant impact on the practice of medicine by offering a cost-effective, rapid, and noninvasive method of evaluation. Furthermore, computer-aided analyses, including image processing-based methods and machine learning techniques, have also shown great potential for a high impact on medicinal evaluations