Spin noise spectroscopy in GaAs

We observe the noise spectrum of electron spins in bulk GaAs by Faraday rotation noise spectroscopy. The experimental technique enables the undisturbed measurement of the electron spin dynamics in semiconductors. We measure exemplarily the electron spin relaxation time and the electron Lande g-factor in n-doped GaAs at low temperatures and find good agreement of the measured noise spectrum with an unpretentious theory based on Poisson distribution probability.Comment: 4 pages, 4 figure

Anomalous Spin Dephasing in (110) GaAs Quantum Wells: Anisotropy and Intersubband Effects

A strong anisotropy of electron spin decoherence is observed in GaAs/(AlGa)As quantum wells grown on (110) oriented substrate. The spin lifetime of spins perpendicular to the growth direction is about one order of magnitude shorter compared to spins along (110). The spin lifetimes of both spin orientations decrease monotonically above a temperature of 80 and 120 K, respectively. The decrease is very surprising for spins along (110) direction and cannot be explained by the usual Dyakonov Perel dephasing mechanism. A novel spin dephasing mechanism is put forward that is based on scattering of electrons between different quantum well subbands.Comment: 4 pages, 3 postscript figures, corrected typo

Physical Activity for Adults with Visual Impairments: Impact of Socio-Demographic Factors

Little is known about what factors influence physical activity participation for adult-aged individuals with visual impairments. Therefore, the purpose of this study was to explore the impact of socio-demographic factors on the physical activity participation of adults with visual impairments. The international physical activity questionnaire-short form and a socio-demographic factor questionnaire were distributed to individuals with visual impairments. A total of 176 adults (Mage = 47.04, 52.8% female) completed the questionnaires. Physical activity and socio-demographic variables were analyzed descriptively and relationships were explored using correlation analysis and multiple regression analysis. On average, participants reported 413.79 minutes of moderate-to-vigorous physical activity and 2058.52 minutes of sedentary active per week. A significant amount of variance of physical activity was explained by the socio-demographic variables in this study. Of the socio-demographic variables measured, only gender emerges as a significant positive predictor of total weekly physical activity. The results of this study both affirm and conflict with previous research. Unlike previous research focusing on those with visual impairments, this study demonstrated that gender was an important predictor of physical activity. This finding is consistent with population-wide data on individuals without disabilities in the United States

Lower Extremity Joint Stiffness During Running in Adolescents with Autism Spectrum Disorder

During late adolescence, children undergo rapid skeletal growth changes leaving the child more vulnerable to injury during physical activity. This is consistent for autistic youth, who reportedly enjoy individual activities, such as running, more than team-based sports [1-3]. Inadequate joint stiffness is one of several factors that may influence injury risk [4]. The purpose of this study was to examine lower extremity joint stiffness in autistic and non-autistic matched controls at self-selected and matched running speeds. Twenty-two persons with a confirmed autism spectrum disorder (ASD) diagnosis and seventeen age, sex, and body mass index controls (CON) were enrolled into the study. Position and force data were collected in the Neuromechanics Laboratory using the motion capture system. Participants were asked to complete a series of over-ground running trials at their self-selected speed and a standardized speed of 3.0 m/s. Joint stiffness was calculated as the quotient of the change in joint moment and the change in joint angle during the energy absorption period of stance. Statistical analyses were performed in SPSS (version 27, IBM Corp.). Stiffness and changes in joint moments were analyzed using 2 (group) x 2 (speed) analyses of variance. There were no significant interactions between groups and speeds (p\u3e0.05) for any variable. Persons with ASD had reduced knee and ankle joint stiffness (all p Persons with ASD had reduced lower extremity stiffness, which was due to their reduced joint moments. Decreased joint stiffness by those with ASD could be indicative of a less efficient running style whereby the elastic recoil is not being optimally utilized.https://digitalcommons.odu.edu/gradposters2022_education/1006/thumbnail.jp

Walking Biomechanics and Energetics of Individuals with a Visual Impairment: A Preliminary Report

Purpose. Although walking gait in sighted populations is well researched, few studies have investigated persons with visual impairments (VIs). Given the lack of physical activity in people with VIs, it is possible that reduced efficiency in walking could adversely affect activity. The purposes of this preliminary study were to (1) examine the biomechanics and energetics utilized during independent and guided walking in subjects with VIs, and (2) compare gait biomechanics between people with VIs and sighted controls. Methods. Three-dimensional motion capture and force platforms were used during independent and guided walking at self-selected speeds. Joint angles, moments, external work, and recovery were compared. Results. The VI group performed independent walking slower and with reduced stride lengths compared with guided walking and sighted controls. Hip range of motion and peak joint moments were reduced during independent walking in the VI group compared with guided walking and controls. Work was greater by 114%, 32%, and 16% in the VI group during independent than during guided walking. Recovery was 11% greater in guided vs. independent walking. Conclusions. In the presented preliminary study among 3 persons with congenital VIs, independent walking was a less efficient mode of walking compared with guided walking and that of sighted controls

Stop fearing blindness! Visually impaired people reflect on the ethics of sighted prospective teachers simulating visual impairment

Disability simulations have developed as a popular profes- sional development tool to help increase knowledge and awareness of disability and facilitate pedagogical learning among prospective and pre-service teachers. The aim of this research is to explore the ethics of sighted people simulating visual impairment from the perspective of visually impaired people. Participants were nine visually impaired adults who read vignettes narrating simulation experiences of prospective physical education teachers in a university setting before being interviewed about their perceptions of what they had read. Interviews were conducted via telephone, and were recorded, transcribed, and subjected to thematic analysis. The themes constructed and discussed in this article from an ethical perspective are: (1) involving visually impaired people in simulated experiences; (2) reinforcing negative attitudes about visually impaired people; (3) tensions involvng touch for pedagogical purposes; and (4) adapting activities and grouping pupils in relation to ‘ability’

Orbital Configurations and Magnetic Properties of Double-Layered Antiferromagnet Cs3_3Cu2_2Cl4_4Br3_3

We report the single-crystal X-ray analysis and magnetic properties of a new double-layered perovskite antiferromagnet, Cs$_3$Cu$_2$Cl$_4$Br$_3$. This structure is composed of Cu$_2$Cl$_4$Br$_3$ double layers with elongated CuCl$_4$Br$_2$ octahedra and is closely related to the Sr$_3$Ti$_2$O$_7$ structure. An as-grown crystal has a singlet ground state with a large excitation gap of $\Delta/k_{\rm B}\simeq 2000$ K, due to the strong antiferromagnetic interaction between the two layers. Cs$_3$Cu$_2$Cl$_4$Br$_3$ undergoes a structural phase transition at $T_{\rm s}\simeq330$ K accompanied by changes in the orbital configurations of Cu$^{2+}$ ions. Once a Cs$_3$Cu$_2$Cl$_4$Br$_3$ crystal is heated above $T_{\rm s}$, its magnetic susceptibility obeys the Curie-Weiss law with decreasing temperature even below $T_{\rm s}$ and does not exhibit anomalies at $T_{\rm s}$. This implies that in the heated crystal, the orbital state of the high-temperature phase remains unchanged below $T_{\rm s}$, and thus, this orbital state is the metastable state. The structural phase transition at $T_{\rm s}$ is characterized as an order-disorder transition of Cu$^{2+}$ orbitals.Comment: 6pages. 6figures, to appear in J. Phys. Soc. Jpn. Vol.76 No.

Bruchlinien der Inklusion

This paper will call for action in one space that is commonly among the first to act as a testing ground for integrated education, physical education. The purposes of this article are twofold: (1) to provide a brief review of research examining integrated physical education from the viewpoints of those with disabilities and (2) to provide several points of reference for future research in this area of inquiry. In addressing these purposes, we first present a review of scholarship salient to the subjective experiences of students with disabilities in integrated physical education. Then, to illustrate and extend this research, an exemplar is provided which highlights a quickly growing line of inquiry into the physical education experiences of students with visual impairments. Finally, we propose and discuss a call for further research transcending any one disability or geographic context and include specific foci for four primary areas of research: understanding placement decisions, examining exemplars, converging or diverging viewpoints, and intersectional perspectives