Terahertz Hall Measurements On Optimally Doped Single Crystal Bi-2212

The infrared Hall angle in optimally doped single crystal $\rm Bi_2 Sr_2 Ca Cu_2 O_{8+x}$ was measured from 3.05 to 21.75 meV as a continuous function of temperature from 25 to 300\,K. In the normal state, the temperature dependence of the real part of the cotangent of the infrared Hall angle obeys the same power law as dc measurements. The measured Hall frequency $\rm \omega_H$ is significantly larger than the expected value based upon ARPES data analyzed in terms of the relaxation time approximation. This discrepancy as well as the temperature dependence of $\rm Re(\cot{\theta_H})$ and $\omega_H$ is well described by a Fermi liquid theory in which current vertex corrections produced by electron-magnon scattering are included.Comment: 10 pages, 2 figure

Infrared Hall effect in high Tc superconductors: Evidence for non-Fermi liquid Hall scattering

Infrared (20-120 cm-1 and 900-1100 cm-1) Faraday rotation and circular dichroism are measured in high Tc superconductors using sensitive polarization modulation techniques. Optimally doped YBCO thin films are studied at temperatures down to 15 K and magnetic fields up to 8 T. At 1000 cm-1 the Hall conductivity varies strongly with temperature in contrast to the longitudinal conductivity which is nearly independent of temperature. The Hall scattering rate has a T^2 temperature dependence but, unlike a Fermi liquid, depends only weakly on frequency. The experiment puts severe constraints on theories of transport in the normal state of high Tc superconductors.Comment: 8 pages, 3 figure

Mid-infrared Hall effect in thin-film metals: Probing the Fermi surface anisotropy in Au and Cu

A sensitive mid-infrared (MIR, 900-1100 cm-1, 112-136 meV) photo-elastic polarization modulation technique is used to measure simultaneously Faraday rotation and circular dichroism in thin metal films. These two quantities determine the complex AC Hall conductivity. This novel technique is applied to study Au and Cu thin films at temperatures down to 20 K and magnetic fields up to 8 T. The Hall frequency is consistent with band theory predictions. We report the first measurement of the MIR Hall scattering rate, which is significantly lower than that derived from Drude analysis of zero magnetic field MIR transmission measurements. This difference is qualitatively explained in terms of the anisotropy of the Fermi surface in Au and Cu.Comment: 14 pages of text, 5 figure

Sum rule for the optical Hall angle

We consider the optical Hall conductivity of a general electronic medium and prove that the optical Hall angle obeys a new sum rule. This sum rule governs the response of an electronic fluid to a Lorentz electric field and can thought of as the transverse counterpart to the f-sum rule in optical conductivity. The physical meaning of this sum rule is discussed, giving a number of examples of its application to a variety of of electronic media.Comment: Four pages. Latex file with two postscript figure

Navigating Autism: Parent Experiences with Coping and Service Connection

This presentation shares findings from a qualitative study exploring the experiences of parents of youth and young adults with ASD and service providers. Themes from interviews and focus groups are discussed. The presenters explore the implications of the study for providing services to individuals with ASD in relation to research, policy and practice

Testing the Tripartite Influence Model Among Heterosexual, Bisexual, and Lesbian Women

This cross-sectional study explored similarities and differences between heterosexual, bisexual, and lesbian women in levels of, and relationships between, the following constructs using a Tripartite Influence Model framework: family, peer, and media appearance pressures, thin- and muscular-ideal internalization, and eating disorder (ED) pathology. Self-identified heterosexual (n = 1,528), bisexual (n = 89), and lesbian (n = 278) undergraduate women completed the Sociocultural Attitudes Towards Appearance Questionnaire-4 and the Eating Disorder Examination-Questionnaire. Sexual orientation differences in appearance pressures, appearance-ideal internalization, and ED pathology were examined via analysis of variance tests. Relationships between these variables were examined with multi-group path analyses, controlling for age, race/ethnicity, and body mass index. Compared with lesbian women, heterosexual and bisexual women reported higher levels of peer appearance pressures. Paths from peer appearance pressures and thin-ideal internalization to shape/weight overvaluation and body dissatisfaction were strongest for bisexual women. Overall, results indicate notable similarities between heterosexual, bisexual, and lesbian women. However, preliminary evidence for potential differences highlights the importance of examining variation in ED risk between sexual minority subgroups

Effective Lorentz Force due to Small-angle Impurity Scattering: Magnetotransport in High-Tc Superconductors

We show that a scattering rate which varies with angle around the Fermi surface has the same effect as a periodic Lorentz force on magnetotransport coefficients. This effect, together with the marginal Fermi liquid inelastic scattering rate gives a quantitative explanation of the temperature dependence and the magnitude of the observed Hall effect and magnetoresistance with just the measured zero-field resistivity as input.Comment: 4 pages, latex, one epsf figure included in text. Several revisions and corrections are included. Major conclusions are the sam

Does the Tripartite Influence Model of Body Image and Eating Pathology Function Similarly Across Racial/Ethnic Groups of White, Black, Latina, and Asian Women?

The tripartite influence model suggests that appearance pressures from family, peers, and the media contribute to thin-ideal internalization, which leads to increased body dissatisfaction and subsequent eating disorder pathology. The tripartite influence model was initially developed and tested among primarily White samples, and emerging research suggests racial/ethnic differences in mean levels of particular model constructs. Consequently, the model\u27s appropriateness for understanding eating disorder risk in racial/ethnic minorities warrants investigation to determine its usefulness in explicating eating disorder risk in diverse populations. Participants in the current study were White (n = 1167), Black (n = 212), Latina (n = 203), and Asian (n = 176) women from five geographically disparate college campuses in the United States. Participants completed the Sociocultural Attitudes Towards Appearance Questionnaire-4, the Multidimensional Body-Self Relations Questionnaire - Appearance Evaluation Subscale, and the Eating Disorder Examination-Questionnaire. Analysis of variance was used to compare mean levels of each construct across racial/ethnic groups. Multigroup structural equation modeling was used to assess the appropriateness of the tripartite influence model for each racial/ethnic group, and to examine differences in the strength of the model pathways across groups. There were significant mean level differences across groups for most model constructs. However, results indicated similar model fit across racial/ethnic groups, with few differences in the strength of model pathways. Findings suggest that although some groups report lower levels of proposed risk factors, the sociocultural risk processes for eating pathology identified through the tripartite influence model are similar across racial/ethnic groups of young adult women. Such information can be used to inform culturally-sensitive interventions

Mapping Lesion-Related Epilepsy to a Human Brain Network

Importance: It remains unclear why lesions in some locations cause epilepsy while others do not. Identifying the brain regions or networks associated with epilepsy by mapping these lesions could inform prognosis and guide interventions. Objective: To assess whether lesion locations associated with epilepsy map to specific brain regions and networks. Design, setting, and participants: This case-control study used lesion location and lesion network mapping to identify the brain regions and networks associated with epilepsy in a discovery data set of patients with poststroke epilepsy and control patients with stroke. Patients with stroke lesions and epilepsy (n = 76) or no epilepsy (n = 625) were included. Generalizability to other lesion types was assessed using 4 independent cohorts as validation data sets. The total numbers of patients across all datasets (both discovery and validation datasets) were 347 with epilepsy and 1126 without. Therapeutic relevance was assessed using deep brain stimulation sites that improve seizure control. Data were analyzed from September 2018 through December 2022. All shared patient data were analyzed and included; no patients were excluded. Main outcomes and measures: Epilepsy or no epilepsy. Results: Lesion locations from 76 patients with poststroke epilepsy (39 [51%] male; mean [SD] age, 61.0 [14.6] years; mean [SD] follow-up, 6.7 [2.0] years) and 625 control patients with stroke (366 [59%] male; mean [SD] age, 62.0 [14.1] years; follow-up range, 3-12 months) were included in the discovery data set. Lesions associated with epilepsy occurred in multiple heterogenous locations spanning different lobes and vascular territories. However, these same lesion locations were part of a specific brain network defined by functional connectivity to the basal ganglia and cerebellum. Findings were validated in 4 independent cohorts including 772 patients with brain lesions (271 [35%] with epilepsy; 515 [67%] male; median [IQR] age, 60 [50-70] years; follow-up range, 3-35 years). Lesion connectivity to this brain network was associated with increased risk of epilepsy after stroke (odds ratio [OR], 2.82; 95% CI, 2.02-4.10; P \u3c .001) and across different lesion types (OR, 2.85; 95% CI, 2.23-3.69; P \u3c .001). Deep brain stimulation site connectivity to this same network was associated with improved seizure control (r, 0.63; P \u3c .001) in 30 patients with drug-resistant epilepsy (21 [70%] male; median [IQR] age, 39 [32-46] years; median [IQR] follow-up, 24 [16-30] months). Conclusions and relevance: The findings in this study indicate that lesion-related epilepsy mapped to a human brain network, which could help identify patients at risk of epilepsy after a brain lesion and guide brain stimulation therapies

Near-Earth plasma sheet boundary dynamics during substorm dipolarization.

We report on the large-scale evolution of dipolarization in the near-Earth plasma sheet during an intense (AL ~ -1000 nT) substorm on August 10, 2016, when multiple spacecraft at radial distances between 4 and 15 R E were present in the night-side magnetosphere. This global dipolarization consisted of multiple short-timescale (a couple of minutes) B z disturbances detected by spacecraft distributed over 9 MLT, consistent with the large-scale substorm current wedge observed by ground-based magnetometers. The four spacecraft of the Magnetospheric Multiscale were located in the southern hemisphere plasma sheet and observed fast flow disturbances associated with this dipolarization. The high-time-resolution measurements from MMS enable us to detect the rapid motion of the field structures and flow disturbances separately. A distinct pattern of the flow and field disturbance near the plasma boundaries was found. We suggest that a vortex motion created around the localized flows resulted in another field-aligned current system at the off-equatorial side of the BBF-associated R1/R2 systems, as was predicted by the MHD simulation of a localized reconnection jet. The observations by GOES and Geotail, which were located in the opposite hemisphere and local time, support this view. We demonstrate that the processes of both Earthward flow braking and of accumulated magnetic flux evolving tailward also control the dynamics in the boundary region of the near-Earth plasma sheet.Graphical AbstractMultispacecraft observations of dipolarization (left panel). Magnetic field component normal to the current sheet (BZ) observed in the night side magnetosphere are plotted from post-midnight to premidnight region: a GOES 13, b Van Allen Probe-A, c GOES 14, d GOES 15, e MMS3, g Geotail, h Cluster 1, together with f a combined product of energy spectra of electrons from MMS1 and MMS3 and i auroral electrojet indices. Spacecraft location in the GSM X-Y plane (upper right panel). Colorcoded By disturbances around the reconnection jets from the MHD simulation of the reconnection by Birn and Hesse (1996) (lower right panel). MMS and GOES 14-15 observed disturbances similar to those at the location indicated by arrows