Spin pumping and magnetization dynamics in metallic multilayers

We study the magnetization dynamics in thin ferromagnetic films and small ferromagnetic particles in contact with paramagnetic conductors. A moving magnetization vector causes \textquotedblleft pumping\textquotedblright of spins into adjacent nonmagnetic layers. This spin transfer affects the magnetization dynamics similar to the Landau-Lifshitz-Gilbert phenomenology. The additional Gilbert damping is significant for small ferromagnets, when the nonmagnetic layers efficiently relax the injected spins, but the effect is reduced when a spin accumulation build-up in the normal metal opposes the spin pumping. The damping enhancement is governed by (and, in turn, can be used to measure) the mixing conductance or spin-torque parameter of the ferromagnet--normal-metal interface. Our theoretical findings are confirmed by agreement with recent experiments in a variety of multilayer systems.Comment: 10 pages, 6 figure

Seed dormancy and germination in Dodonaea viscosa (Sapindaceae) from south-western Saudi Arabia

Dodonaea viscosa (Sapindaceae) is widespread in the mountainous highlands of the southwestern part of the Kingdom of Saudi Arabia, where it is a medicinally important species for the people of Saudi Arabia. Seeds of this species were collected from Mount Atharb in the Al-Baha region, at an altitude of 2100 m. The aims of this study were to determine if the seeds of D. viscosa have physical dormancy (i.e. a water-impermeable seed coat) and, if so, what treatments would break dormancy, and what conditions promote germination after dormancy has been broken. The dormancy-breaking treatments included: soaking of seeds in concentrated sulfuric acid (H2SO4) for 10 minutes, immersion in boiling water for 10 minutes and exposure to 50 °C for 1 minute. After seeds had been pre-treated with H2SO4, to break dormancy, they were incubated at constant temperatures from 5 to 35°C, under 12-h photoperiods or in continuous darkness, and germination recorded. Salinity tolerance was investigated by incubating acid-scarified seeds in 0, 100, 200 and 300 mM NaCl in the light at 25°C. Untreated seeds had low final germination (30%). Seeds that had been acid-scarified, immersed in boiling water or exposed to 50 °C all achieved 91% subsequently when incubated at 25°C. Thus, seeds of this species in Saudi Arabia have physical dormancy, which can be broken by all three treatments designed to increase the permeability of the testa. After pre-treatment, there was a broad optimum constant temperature for germination that ranged between 5-25°C but germination was inhibited by higher temperatures (30 and 35°C). Light had little effect on this germination response. Scarified seeds were also sensitive to salinity, with the highest germination in distilled water and complete inhibition in 400 mM NaCl. Seeds that failed to germinate in saline treatments were mostly able to germinate on transfer to distilled water, suggesting osmotic inhibition

Diversity of butterflies (Lepidoptera: Papilionoidea and Hesperoidea) of Dachigam National Park, Jammu and Kashmir, India

This preliminary study documented the diversity of butterflies of Dachigam National Park from 2004 to 2007.The field investigation was confined mostly to lower areas of the National Park and 27 species of butterflies were recorded. Except Hesperiidae, all the families were mostly active from April to August. 18 species showed mud puddling behaviour. Junonia orithya (Linnaeus) (Blue Pansy) and Neptis sappho Pallas (Pallas’ Sailer) are reported for the first time from Kashmir Valley

Real-time control of a microfluidic channel for size-independent deformability cytometry

10.1088/0960-1317/22/10/105037Journal of Micromechanics and Microengineering2210-JMMI

Size-independent deformability cytometry with active feedback control of microfluidic channels

15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 201121053-105

Corporate governance structure and performance of Malaysian listed companies.

NoThis study investigates the relationship between the corporate governance structure and performance of 347 companies listed on the Kuala Lumpur Stock Exchange (KLSE) between 1996 and 2000. We found board size and top five substantial shareholdings to be significantly associated with both market and accounting performance measures. In addition, we found a significant relationship between multiple directorships and market performance while role duality and managerial shareholdings are significantly associated with accounting performance. The result is robust with respect to controls for gearing, company size, industry membership and growth opportunities