The Influence of Magnetic Domain Walls on Longitudinal and Transverse Magnetoresistance in Tensile Strained (Ga,Mn)As Epilayers

We present a theoretical analysis of recent experimental measurements of magnetoresistance in (Ga,Mn)As epilayers with perpendicular magnetic anisotropy. The model reproduces the field-antisymmetric anomalies observed in the longitudinal magnetoresistance in the planar geometry (magnetic field in the epilayer plane and parallel to the current density), as well as the unusual shape of the accompanying transverse magnetoresistance. The magnetoresistance characteristics are attributed to circulating currents created by the presence of magnetic domain walls

Persistent Decadal-Scale Rainfall Variability in the Tropical South Pacific Convergence Zone Through the Past Six Centuries

Modern Pacific decadal variability (PDV) has global impacts; hence records of PDV from the pre-instrumental period are needed to better inform models that are used to project future climate variability. We focus here on reconstructing rainfall in the western tropical Pacific (Solomon Islands; similar to 9.5 degrees S, similar to 160 degrees E), a region directly influenced by PDV, using cave deposits (stalagmite). A relationship is developed between delta O-18 variations in the stalagmite and local rainfall amount to produce a 600 yr record of rainfall variability from the South Pacific Convergence Zone (SPCZ). We present evidence for large (similar to 1.5 m), abrupt, and periodic changes in total annual rainfall amount on decadal to multidecadal timescales since 1423 +/- 5 CE (Common Era) in the Solomon Islands. The timing of the decadal changes in rainfall inferred from the 20th-century portion of the stalagmite delta O-18 record coincides with previously identified decadal shifts in PDV-related Pacific ocean-atmosphere behavior (Clement et al., 2011; Deser et al., 2004). The Solomons record of PDV is not associated with variations in external forcings, but rather results from internal climate variability. The 600 yr Solomon Islands stalagmite delta O-18 record indicates that decadal oscillations in rainfall are a persistent characteristic of SPCZ-related climate variability.Taiwan ROC NSCNTU 101-2116-M-002-009, 102-2116-M-002-016, 101R7625Geological Science

Zee electrical interconnect

An interconnect, having some length, that reliably connects two conductors separated by the length of the interconnect when the connection is made but in which one length if unstressed would change relative to the other in operation. The interconnect comprises a base element an intermediate element and a top element. Each element is rectangular and formed of a conducting material and has opposed ends. The elements are arranged in a generally Z-shape with the base element having one end adapted to be connected to one conductor. The top element has one end adapted to be connected to another conductor and the intermediate element has its ends disposed against the other end of the base and the top element. Brazes mechanically and electrically interconnect the intermediate element to the base and the top elements proximate the corresponding ends of the elements. When the respective ends of the base and the top elements are connected to the conductors, an electrical connection is formed therebetween, and when the conductors are relatively moved or the interconnect elements change length the elements accommodate the changes and the associated compression and tension forces in such a way that the interconnect does not mechanically fatigue

Association between pain outcomes and race and opioid treatment: Retrospective cohort study of Veterans

We examined whether pain outcomes (pain interference, perceived pain treatment effectiveness) vary by race and then whether opioid use moderates these associations. These analyses are part of a retrospective cohort study among 3,505 black and 46,203 non-Hispanic, white Department of Veterans Affairs (VA) patients with diagnoses of chronic musculoskeletal pain who responded to the 2007 VA Survey of Healthcare Experiences of Patients (SHEP). We used electronic medical record data to identify prescriptions for pharmacologic pain treatments in the year after diagnosis (Pain Diagnosis index visit) and before the SHEP index visit (the visit that made one eligible to complete the SHEP); pain outcomes came from the SHEP. We found no significant associations between race and pain interference or perceived effectiveness of pain treatment. VA patients with opioid prescriptions between the Pain Diagnosis index visit and the SHEP index visit reported greater pain interference on the SHEP than those without opioid prescriptions during that period. Opioid prescriptions were not associated with perceived treatment effectiveness for most patients. Findings raise questions about benefits of opioids for musculoskeletal pain and point to the need for alternative treatments for addressing chronic noncancer pain

Tight-binding study of interface states in semiconductor heterojunctions

Localized interface states in abrupt semiconductor heterojunctions are studied within a tight-binding model. The intention is to provide a microscopic foundation for the results of similar studies which were based upon the two-band model within the envelope function approximation. In a two-dimensional description, the tight-binding Hamiltonian is constructed such that the Dirac-like bulk spectrum of the two-band model is recovered in the continuum limit. Localized states in heterojunctions are shown to occur under conditions equivalent to those of the two-band model. In particular, shallow interface states are identified in non-inverted junctions with intersecting bulk dispersion curves. As a specific example, the GaSb-AlSb heterojunction is considered. The matching conditions of the envelope function approximation are analyzed within the tight-binding description.Comment: RevTeX, 11 pages, 3 figures, to appear in Phys. Rev.

Learning From Each Other: Experiences of Rural Principals in a Networked Learning Community

Rural school principals in Tennessee face serious challenges in leading their schools, including isolation, high turnover, and a lack of instructional leadership skills. Facilitated by a state university, the Tennessee Rural Principals Network (TRPN) was developed to provide professional learning opportunities for rural school principals. The purpose of this study was to explore the perceptions of principals in rural schools who participated in the TRPN during the years 2019–2021 (n = 133). The study used a basic qualitative research design with semi-structured interviews of 12 participants. Through our data analysis, key learning strengths and challenges were identified and organized under the codes of learning needs, coaching, mentoring, and networking. From these categories, we developed three themes: (a) sharing and collaborating through networks; (b) building capacity through mentoring and coaching; and (c) addressing the learning needs of principals in a rural context. Findings revealed that principals were pleased with the network and felt it helped them better navigate their roles as rural principals by providing the tools to develop best practices and a network to share ideas and resources

Interface states in junctions of two semiconductors with intersecting dispersion curves

A novel type of shallow interface state in junctions of two semiconductors without band inversion is identified within the envelope function approximation, using the two-band model. It occurs in abrupt junctions when the interband velocity matrix elements of the two semiconductors differ and the bulk dispersion curves intersect. The in-plane dispersion of the interface state is found to be confined to a finite range of momenta centered around the point of intersection. These states turn out to exist also in graded junctions, with essentially the same properties as in the abrupt case.Comment: 1 figur

Prediction of Anisotropic Single-Dirac-Cones in Bi1−x{}_{1-x}Sbx{}_{x} Thin Films

The electronic band structures of Bi${}_{1-x}$Sb${}_{x}$ thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi${}_{1-x}$Sb${}_{x}$ thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band-gap, which can be used in a general two-dimensional system that has a non-parabolic dispersion relation as in a Bi${}_{1-x}$Sb${}_{x}$ thin film system

Retaining young people in a longitudinal sexual health survey: a trial of strategies to maintain participation

Background: There is an increasing trend towards lower participation in questionnaire surveys. This reduces representativeness, increases costs and introduces particular challenges to longitudinal surveys, as researchers have to use complex statistical techniques which attempt to address attrition. This paper describes a trial of incentives to retain longitudinal survey cohorts from ages 16 to 20, to question them on the sensitive topic of sexual health.Methods: A longitudinal survey was conducted with 8,430 eligible pupils from two sequential year groups from 25 Scottish schools. Wave 1 (14 years) and Wave 2 (16 years) were conducted largely within schools. For Wave 3 (18 years), when everyone had left school, the sample was split into 4 groups that were balanced across predictors of survey participation: 1) no incentive; 2) chance of winning one of twenty-five vouchers worth 20; pound 3) chance of winning one 500 pound voucher; 4) a definite reward of a 10 pound voucher sent on receipt of their completed questionnaire. Outcomes were participation at Wave 3 and two years later at Wave 4. Analysis used logistic regression and adjusted for clustering at school level.Results: The only condition that had a significant and beneficial impact for pupils was to offer a definite reward for participation (Group 4). Forty-one percent of Group 4 participated in Wave 3 versus 27% or less for Groups 1 to 3. At Wave 4, 35% of Group 4 took part versus 25% or less for the other groups. Similarly, 22% of Group 4 participated in all four Waves of the longitudinal study, whereas for the other three groups it was 16% or less that participated in full.Conclusions: The best strategy for retaining all groups of pupils and one that improved retention at both age 18 and age 20 was to offer a definite reward for participation. This is expensive, however, given the many benefits of retaining a longitudinal sample, we recommend inclusion of this as a research cost for cohort and other repeat-contact studies