Effect of plasma rotation on the resonance magnetic perturbations at the edge of tokamak plasmas

In the frame of one-fluid MHD the pressure perturbation resonant excitation by external low frequency helical magnetic perturbations near the plasma edge is investigated. The plasma rotation plays a key role in this phenomenon. The plasma response has been taken into account. These pressure perturbations may affect stability of the ballooning and peeling modes.В рамках одножидкостной МГД исследовано резонансное возбуждение возмущений давления у края плазмы внешними низкочастотными винтовыми возмущениями магнитного поля. Вращение плазмы играет ключевую роль в этом явлении. Учтен отклик плазмы. Эти возмущения давления могут влиять на устойчивость баллонных и пилинг-мод.У рамках однорідинної МГД досліджено резонансне збудження збурень тиску біля краю плазми зовнішніми низькочастотними гвинтовими збуреннями магнітного поля. Обертання плазми відіграє ключову роль у цьому явищі. Враховано відгук плазми. Ці збурення тиску можуть впливати на стійкість балонних та пілінг-мод

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.

Role of Ectonucleotidases in the Synapse Formation During Brain Development: Physiological and Pathological Implications

Extracellular adenine nucleotides and nucleosides, such as ATP and adenosine, are among the most recently identified and least investigated diffusible signaling factors that contribute to the structural and functional remodeling of the brain, both during embryonic and postnatal development. Their levels in the extracellular milieu are tightly controlled by various ectonucleotidases: ectonucleotide pyrophosphatase/phosphodiesterases (E-NPP), alkaline phosphatases (AP), ectonucleoside triphosphate diphosphohydrolases (E-NTPDases) and ecto-5'-nucleotidase (eN). During central nervous system development and in adulthood all ectonucleotidases have diverse expression pattern, cell specific localization and function. Formation, maturation, and refinement of synaptic contacts are influenced by neurotransmitters and neuromodulators, and control of extracellular adenine nucleotide levels by ectonucleotidases are important for understanding the role of purinergic signaling in developing tissues and potential targets in developmental disorders such as autism