737 research outputs found

    Stability of Spinmotive Force in Perpendicularly Magnetized Nanowires under High Magnetic Fields

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    Spinmotive force induced by domain wall motion in perpendicularly magnetized nanowires is numerically demonstrated. We show that using nanowires with large magnetic anisotropy can lead to a high stability of spinmotive force under strong magnetic fields. We observe spinmotive force in the order of tens of microvolt in a multilayered Co/Ni nanowire and in the order of several hundred microvolt in a FePt nanowire; the latter is two orders of magnitude greater than that in permalloy nanowires reported previously. The narrow structure and low mobility of a domain wall under magnetic fields in perpendicularly magnetized nanowires permits downsizing of spinmotive force devices.Comment: submitted to Applied Physics Letter

    Effects of mechanical rotation on spin currents

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    We study the Pauli--Schr\"odinger equation in a uniformly rotating frame of reference to describe a coupling of spins and mechanical rotations. The explicit form of the spin-orbit interaction (SOI) with the inertial effects due to the mechanical rotation is presented. We derive equations of motion for a wavepacket of electrons in two-dimensional planes subject to the SOI. The solution is a superposition of two cyclotron motions with different frequencies and a circular spin current is created by the mechanical rotation.Comment: 4 pages, 2 figure

    Revisiting substorm events with preonset aurora

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    Nishimura et al. (2010) proposed a new plasma intrusion or preonset aurora scenario of substorm triggering. In this scenario, a substorm is triggered by a fast earthward flow generated at the distant neutral line which corresponds to a preonset auroral streamer or arc in the ionosphere propagating from the auroral poleward boundary to the initial auroral brightening site, i.e., preonset aurora. In the present paper, we revisited three substorm events reported as being triggered by such a mechanism related to preonset auroras, based on THEMIS ground-based all-sky imager data. Unlike previous studies, we examined the arrival timing of the preonset aurora relative to the three steps of auroral onset arc development (initial brightening, enhancement of the wave-like structure, and poleward expansion) to make the role of the preonset aurora in the auroral steps clearer. Our detailed timing analysis found that preonset auroral streamers reached the auroral onset arc but away from the initial brightening site after initial brightening for two events, while no preonset aurora reaching the initial brightening site could be identified for the other event. This result suggests that the processes associated with auroral streamers are unlikely to affect at least initial brightening, even if we consider not only the presence and arrival timing and location of the auroral streamers but also the scale of the corresponding flow and flow vortices. We list a series of open questions for testing the preonset aurora scenario further in future studies.</p

    Multicomponent Bright Solitons in F = 2 Spinor Bose-Einstein Condensates

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    We study soliton solutions for the Gross--Pitaevskii equation of the spinor Bose--Einstein condensates with hyperfine spin F=2 in one-dimension. Analyses are made in two ways: by assuming single-mode amplitudes and by generalizing Hirota's direct method for multi-components. We obtain one-solitons of single-peak type in the ferromagnetic, polar and cyclic states, respectively. Moreover, twin-peak type solitons both in the ferromagnetic and the polar state are found.Comment: 15 pages, 8 figure

    O espectro das falências ovarianas ligadas ao cromossomo X

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    Clinically ovarian failure is presented by primary or secondary amenorrhea and high levels of pituitary gonadotropins mainly FSH. Monossomy or X-chromosome rearrangements are among a variable number of suggested etiopathogenic factors of ovarian failure in young women. Besides in Turner syndrome (X-monossomy or mosaicism), where the short stature and sexual infantilism point to the diagnosis, X-chromosome long arm (Xq) rearrangements, or genetic mutations of genes mapped at this segment are related with ovarian failure presented in prepubertal girls and in young women without other clinical signal. The present revision focuses these chromosomal abnormalities, some of them disclosed by conventional cytogenetic methods and other only disclosed by means of molecular biological toolsA falência ovariana manifesta-se clinicamente por amenorréia primária ou secundária, e do ponto de vista hormonal caracteriza-se pelos níveis elevados de gonadotrofinas hipofisárias, principalmente FSH, cuja etiologia pode ser atribuída a varias causas, como redução numérica ou rearranjos do cromossomo X, entre outras. Além da síndrome de Turner (monossomia do cromossomo X, com ou sem mosaicismo cromossômico), cujo principal estigma - a baixa estatura - e o infantilismo sexual apontam o diagnóstico, rearranjos do braço longo de X (Xq), ou mutações instaladas em genes mapeados neste cromossomo estão relacionados com a falência ovariana em meninas pré-púberes e em mulheres adultas jovens, sem outros sinais clínicos. Neste cromossomo, nos segmentos da falência ovariana precoce (FOP1 e FOP2) situam-se genes já relacionados à insuficiência ovariana de instalação precoce. Esta revisão trata destas alterações, algumas detectadas pelas técnicas citogenéticas convencionais, outras somente por meio de recursos de biologia molecularUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Disciplina de Endocrinologia e MetabologiaUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de GinecologiaUNIFESP, EPM, Disciplina de Endocrinologia e MetabologiaUNIFESP, EPM, Depto. de GinecologiaSciEL

    Effect of the FACs distribution on the middle and low latitude ionospheric current patterns deduced by a 2-D ionospheric potential solver (GEMSIS-POT)

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    第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月15日(火) 国立極地研究所 2階大会議室前フロ

    Pressure-driven instability in auroral images to create auroral patches

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    第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月27日(火) 国立極地研究所 2階大会議
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