Electric-Field-Induced Resonant Spin Polarization in a Two-Dimensional Electron Gas

Electric response of spin polarization in two-dimensional electron gas with structural inversion asymmetry subjected to a magnetic field was studied by means of the linear and non-linear theory and numerical simulation with the disorder effect. It was found by Kubo linear reponse theory that an electric resonant response of spin polarization occurs when the Fermi surface is located near the crossing of two Landau levels, which is induced from the competition between the spin-orbit coupling and Zeeman splitting. The scaling behavior was investigated with a simplified two-level model by non-linear method, and the resonant peak value is reciprocally proportional to the electric field at low temperatures and to temperature for finite electric fields. Finally numerical simulation illustrated that impurity potential opens an enegy gap near the resonant point and suppresses the effect gradually with the increasing strength of disorder. This resonant effect may provide an efficient way to control spin polarization by an external electric field.Comment: 6 pages, 5 figure

Influences of stress, individual and family processes on rural low-income children’s internalizing and externalizing behaviors

Contextual stress (e.g., economic pressure, acculturative stress) places rural children at risk for adverse outcomes. Prior studies using rural samples to understand the stress processes at the individual and family levels have been predominantly dyadic in focus. Given family members are interdependent, it is interesting to explore whether family variables of particular interest on the family process as a whole can help explain the stress process. Guided by the family stress model, this dissertation used structural equation modeling to explore the relationships among contextual stress (i.e., economic pressure, acculturative stress), individual process (e.g., maternal depressive symptoms), family process (e.g., family rituals) and child behavior outcomes among rural low-income families in general as well as rural low-income families of Latinx origin. Data were collected from rural low-income mothers who participated in a multi-state project Rural Families Speak about Health (RFSH) and an outgrowth project focusing on rural Latinx immigrant families in the Midwest. Overall, the findings confirmed the significant roles of individual and family processes in the relation between contextual stress and rural low-income child behavior outcomes. In particular, the findings provided empirical evidence, albeit preliminary, to support the extension and elaboration of the FSM in ways that include family rituals as a mediator and acculturative stress as a contextual stressor specific to culture. In the first study, economic pressure was associated with more maternal depressive symptoms, which in turn was related to weaker co-parenting alliance. Family rituals might serve as a mediator between co-parenting alliance and child externalizing behaviors for rural low-income families in general. The economic stress process did not vary by families with different age groups of children (i.e., younger vs. older children). In the second study, maternal depressive symptoms, as influenced by economic pressure and acculturative stress, was associated with lower levels of parenting competence, which in turn was related to less meaning ascribed in family rituals and heightened risk for child externalizing behaviors for low-income Latinx immigrant families in the rural Midwest. Implications, including recommendations for future research and suggestions for practice and policy were also discussed

Reflexiones en torno a las características formales de los útiles líticos: una visión desde el análisis traceológico

Desde los inicios, los estudiosos de la Prehistoria han hecho esfuerzos considerables por caracterizar los objetos arqueológicos que aparecían en los yacimientos. La detallada descripción formal de la industria lítica, de la cerámica, de los útiles de metal, etc., han llenado páginas y páginas de artículos y libros. Unas descripciones que, sin embargo, no han cesado en la actualidad. No hay trabajo que se precie que no dedique una parte importante de su contenido a dar a conocer cómo es el registro arqueológico que se está tratando. Aunque la clasificación es un modo de ordenar una realidad para que pueda ser reconocida por el resto de arqueólogos, las propuestas tipológicas han tenido y siguen teniendo a menudo una finalidad prioritaria: proponer al lector los elementos de base a partir de los cuales encajonar los restos arqueológicos a unas culturas y cronologías preestablecidas