Boltzmann Equations for Spin and Charge Relaxations in Superconductors

In a superconductor coupled with a ferromagnetic metal, spin and charge imbalances can be induced by injecting spin-polarized electron current from the ferromagnetic metal. We theoretically study a nonequilibrium distribution of quasiparticles in the presence of spin and charge imbalances. We show that four distribution functions are needed to characterize such a nonequilibrium situation, and derive a set of linearized Boltzmann equations for them by extending the argument by Schmid and Sch\"{o}n based on the quasiclassical Green's function method. Using the Boltzmann equations, we analyze the spin imbalance in a thin superconducting wire weakly coupled with a ferromagnetic electrode. The spin imbalance induces a shift $\delta\mu$ ($- \delta \mu$) of the chemical potential for up-spin (down-spin) quasiparticles. We discuss how $\delta \mu$ is relaxed by spin-orbit impurity scattering.Comment: 16 pages, 2 figure

‘Teachers’ to ‘academics’: the implementation of a modernisation project at one UK post-92 university

Among the many external forces that have impacted upon institutions, league tables have been the dynamic to which universities across the world are now responding. Following the appointment of a new vice-chancellor at one post-92 UK university, a modernisation project was introduced aimed at maximising the institutions’ research standing. For the institutional actors, the university’s lecturers, this modernisation project demanded a change in their working practices from one which had focused on teaching related activities to a situation where an emphasis was to be placed upon research. This study examines how university teachers at this institution understood and responded to the modernisation project to acquire research skills and provides an insight into a path-breaking strategic plan that was enacted within an historically dependent setting. It muses on the dialectics of institutional path dependency and the path breaking effect of a modernisation project that was stimulated by new managerialism

Stomata regulation by tissue-specific expression of the Citrus sinensis MYB61 transcription factor improves water-use efficiency in Arabidopsis

Water-use efficiency (WUE) is a quantitative measurement of biomass produced per volume of water transpired by a plant. WUE is an important physiological trait for drought response to mitigate the water deficiency. In this work, a cisgenic construction from Citrus sinensis was developed and its function in the improvement of WUE was evaluated in Arabidopsis. Sequences of the CsMYB61 coding region, a transcription factor implicated in the closure of stomata, together with a putative stomata-specific promoter from CsMYB15, were identified and cloned. The protein encoded in the CsMYB61 locus harbors domains and motifs characteristic of MYB61 proteins. In addition, a 1.2 kb promoter region of the gene CsMYB15 (pCsMYB15) containing regulatory elements for expression in guard cells and in response to Abscisic Acid (ABA) and light was isolated. In Arabidopsis, pCsMYB15 directs the expression of the reporter gene GUS in stomata in the presence of light. In addition, transgenic lines expressing the CsMYB61 coding region under transcriptional control of pCsMYB15 have a normal phenotype under in vitro and greenhouse conditions. These transgenic lines exhibited a smaller opening of the stomata pore, lower stomatal conductance and respiration rate, enhanced sensitivity to exogenous ABA, and high drought stress tolerance. Our results indicate that stomata-specific expression of CsMYB61 enhances water use efficiency under drought conditions in Arabidospi

Kerr effect of two-medium layered systems

Detailed and practical expressions are given for the magneto-optical Kerr effect (MOKE) for various configurations of two media. One is a magneto-optic (MO) one, and the other is a nonmagnetic (NM) medium. For a system of two thick media with a single interface, with a first-order approximation in MOKE term Q, the Kerr function is determined by the product of a MOKE term Q and an optical term η. A second type of system includes a thin MO (or NM) layer deposited on a thick NM (or MO) substrate. For a MO/(NM-substrate) configuration, the Kerr function is related to the Kerr effects from the air/MO and MO/NM interfaces, and to the Faraday effects of the MO layer, as well as to interference effects. The enhancement factor can be expected to be large by proper choice of materials. For a NM/(MO-substrate) configuration, the total Kerr function is related to the Kerr effect from the NM/MO interface and can be enhanced by interference. The enhancement factor is expected to be less than one if the NM layer is strongly absorbing. Calculations of Kerr effects for examples of the PtMnSb/AuAl2 and Fe/Cu configurations are given. These indicate that the peaks shown in the onset region of the interband transitions of Cu can be attributed to a dramatic change of the refractive index in that region. The merits of a MO/(NM-metallic) structure have been evaluated, and indicate that a better Kerr enhancement effect can be achieved if the refractive index of the MO layer is larger than one and is much larger than that of the metallic material. A drawback to this configuration comes from the fact that a MO material with a large refractive index value usually is not expected to have a large intrinsic Kerr effect. Journal of Applied Physics is copyrighted by The American Institute of Physics