Dynamical properties of a trapped dipolar Fermi gas at finite temperature

We investigate the dynamical properties of a trapped finite-temperature normal Fermi gas with dipole-dipole interaction. For the free expansion dynamics, we show that the expanded gas always becomes stretched along the direction of the dipole moment. In addition, we present the temperature and interaction dependences of the asymptotical aspect ratio. We further study the collapse dynamics of the system by suddenly increasing the dipolar interaction strength. We show that, in contrast to the anisotropic collapse of a dipolar Bose-Einstein condensate, a dipolar Fermi gas always collapses isotropically when the system becomes globally unstable. We also explore the interaction and temperature dependences for the frequencies of the low-lying collective excitations.Comment: 11 pages, 7 figure

Pretreatment of seed with H2O2 enhances drought tolerance of wheat (Triticum aestivum L.) seedlings

Drought is an important environmental constraint limiting the productivity of many crops worldwide. Seedling tolerance to drought is crucial for crop growth and development through the whole season under water-limited condition. Experiments were conducted to investigate the effects of seedpretreatment by hydrogen peroxide (H2O2) on drought tolerance in wheat (Triticum aestivum L.) seedlings. H2O2-pretreated seeds exhibited 56% higher in germination rate than the water-pretreated seeds (control) under PGE-induced drought condition. Level of H2O2 in seedlings arising from H2O2- treated seeds grown under drought stress was markedly lower than the controls, indicating the operation of antioxidant system in them. These seedlings exhibited increased growth characteristics including higher net photosynthetic rate, leaf area and dry weight. Moreover, H2O2 treatment improved water use efficiency (WUE) and proline level. H2O2 pretreatment enhanced the membrane stability, as revealed from greatly reduced membrane damage rate (MDA) and malondialdehyde (MDA) content. Theseedlings showed the higher expression of antioxidative enzyme such as catalase (CAT) and ascorbate peroxidase (APX). The present data suggest that H2O2, a stress signal, could trigger the activation of antioxidants in seeds, which persists in the seedlings to alleviate the oxidative damage, leading to improvements in physiological attributes for the seedling growth under drought