Polarity Reversal of a Magnetic Vortex Core by a Unipolar, Nonresonant In-plane Pulsed Magnetic Field

We report the polarity reversal of a magnetic vortex core using a nonresonant in-plane pulsed magnetic field of arbitrary waveform studied using time-resolved x-ray photoemission electron microscopy and micromagnetic simulations. The imaging and simulations show that a 5 mT pulse, higher than the critical field for nonlinear effects, effectively leads to the randomization of the vortex core polarity. The micromagnetic simulations further show that the onset of stochastic core polarity randomization does not necessarily coincide with the critical reversal field, leading to a field window for predictable core reversal

Polarity Reversal of a Magnetic Vortex Core by a Unipolar, Nonresonant In-plane Pulsed Magnetic Field

We report the polarity reversal of a magnetic vortex core using a nonresonant in-plane pulsed magnetic field of arbitrary waveform studied using time-resolved x-ray photoemission electron microscopy and micromagnetic simulations. The imaging and simulations show that a 5 mT pulse, higher than the critical field for nonlinear effects, effectively leads to the randomization of the vortex core polarity. The micromagnetic simulations further show that the onset of stochastic core polarity randomization does not necessarily coincide with the critical reversal field, leading to a field window for predictable core reversal

A primal--dual algorithm as applied to optimal control problems

We propose a primal--dual technique that applies to infinite dimensional equality constrained problems, in particular those arising from optimal control. As an application of our general framework, we solve a control-constrained double integrator optimal control problem and the challenging control-constrained free flying robot optimal control problem by means of our primal--dual scheme. The algorithm we use is an epsilon-subgradient method that can also be interpreted as a penalty function method. We provide extensive comparisons of our approach with a traditional numerical approach

Quantitative assessment of participant knowledge and evaluation of participant satisfaction in the CARES training program

BACKGROUND: The purpose of the Community Alliance for Research Empowering Social change (CARES) training program was to (1) train community members on evidence-based public health, (2) increase their scientific literacy, and (3) develop the infrastructure for community-based participatory research (CBPR). OBJECTIVES: We assessed participant knowledge and evaluated participant satisfaction of the CARES training program to identify learning needs, obtain valuable feedback about the training, and ensure learning objectives were met through mutually beneficial CBPR approaches. METHODS: A baseline assessment was administered before the first training session and a follow-up assessment and evaluation was administered after the final training session. At each training session a pretest was administered before the session and a posttest and evaluation were administered at the end of the session. After training session six, a mid-training evaluation was administered. We analyze results from quantitative questions on the assessments, pre- and post-tests, and evaluations. RESULTS: CARES fellows knowledge increased at follow-up (75% of questions were answered correctly on average) compared with baseline (38% of questions were answered correctly on average) assessment; post-test scores were higher than pre-test scores in 9 out of 11 sessions. Fellows enjoyed the training and rated all sessions well on the evaluations. CONCLUSIONS: The CARES fellows training program was successful in participant satisfaction and increasing community knowledge of public health, CBPR, and research method ology. Engaging and training community members in evidence-based public health research can develop an infrastructure for community–academic research partnerships

Parenting practices in pregnancy smokers compared to non smokers

BACKGROUND: The present investigation compared parenting practices in a sample of preschoolers whose mothers reported smoking during pregnancy versus those who did not. METHODS: A sample of n = 216, 3.0- to 5.11-year-old children, participants in an ongoing longitudinal study, was separated into those reportedly exposed to smoking in utero and those who were not. Parenting practices were compared between the two groups, using T-tests and exact logistic regressions. Multiple linear regressions and multivariate logistic regressions were used to examine the association between smoking status and parenting, controlling for variables also known to be associated with parenting practices. RESULTS: Current study findings suggest that smoking during pregnancy is associated with harsh parenting practices. CONCLUSIONS: Study results highlight the possible role of parenting in disruptive outcomes well-known in toddlers exposed to nicotine in utero and have implications for targeting early interventions in these populations

Nonlinear Vortex Dynamics and Transient Domains in Ferromagnetic Disks

We report a time-resolved imaging and micromagnetic simulation study of the relaxation dynamics of a magnetic vortex in the nonlinear regime. We use time-resolved photoemission electron microscopy and micromagnetic calculations to examine the emergence of nonlinear vortex dynamics in patterned Ni80Fe20 disks in the limit of long field pulses. We show for core shifts beyond ∼20%–25% of the disk radius, the initial motion is characterized by distortions of the vortex, a transient cross-tie wall state, and instabilities in the core polarization that influence the core trajectories

Health Utilities Associated with Hemoglobin Levels and Blood Loss in Postmenopausal Women: The Women's Health Initiative

AbstractObjectivesThe purpose of our study was to use health-related quality of life data from the Women's Health Initiative to calculate health-related utility weights and examine differences in these health utility weights across different hemoglobin (Hgb) levels. These utility weights could then be used in future cost-effectiveness studies.MethodsHealth utility weights were measured by the Short Form-6D (SF-6D), a health utility index derived from the Short Form Medical Outcomes questionnaire. Adjusted least square means were calculated for each level of Hgb at baseline and in longitudinal regression analysis the relationship between change in Hgb and change in the SF-6D was examined. Both baseline and longitudinal analyses were performed for all postmenopausal women and separately for those with self-reported heart failure, cancer, and osteoarthritis.ResultsWomen with Hgb in the anemic range had lower health utility weights than those with higher Hgb levels. Longitudinally, a loss of of 2 g/dl Hgb or more was associated with a statistically significant and clinically meaningfully decline in SF-6D in all participants and also in the group of participants with cancer and osteoarthritis, but not in those with heart failure.ConclusionsLower levels of Hgb and a loss of Hgb are associated with a statistically significant and clinically meaningful decrement in health utility in all postmenopausal women we studied and also in those with chronic conditions

Shock Diffraction by Convex Cornered Wedges for the Nonlinear Wave System

We are concerned with rigorous mathematical analysis of shock diffraction by two-dimensional convex cornered wedges in compressible fluid flow governed by the nonlinear wave system. This shock diffraction problem can be formulated as a boundary value problem for second-order nonlinear partial differential equations of mixed elliptic-hyperbolic type in an unbounded domain. It can be further reformulated as a free boundary problem for nonlinear degenerate elliptic equations of second order. We establish a first global theory of existence and regularity for this shock diffraction problem. In particular, we establish that the optimal regularity for the solution is $C^{0,1}$ across the degenerate sonic boundary. To achieve this, we develop several mathematical ideas and techniques, which are also useful for other related problems involving similar analytical difficulties.Comment: 50 pages;7 figure

Nonlinear Vortex Dynamics and Transient Domains in Ferromagnetic Disks

We report a time-resolved imaging and micromagnetic simulation study of the relaxation dynamics of a magnetic vortex in the nonlinear regime. We use time-resolved photoemission electron microscopy and micromagnetic calculations to examine the emergence of nonlinear vortex dynamics in patterned Ni80Fe20 disks in the limit of long field pulses. We show for core shifts beyond ∼20%–25% of the disk radius, the initial motion is characterized by distortions of the vortex, a transient cross-tie wall state, and instabilities in the core polarization that influence the core trajectories