Asian Journal of Andrology (2011) 13, 254-265; doi:10.1038/aja.2010.99; published online 20 December 2010″
“Bituminaria bituminosa (L) C.H. Stirton (Fabaceae) accumulates high concentrations of the furanocoumarins (FCs) angelicin and psoralen, which

protect against infection and herbivory. The effects on FC accumulation of the exposure of two populations of B. bituminosa to abiotic stress (cold, heat and drought) under field conditions were determined, as well as the effect of temperature under controlled conditions, in hydroponic culture. In field conditions, psoralen and angelicin levels in the leaf dry matter were 400-6000 and 1500-11,000 Dibutyryl-cAMP concentration mu g g(-1), respectively. There were significant effects of population on the psoralen concentration and psoralen:angelicin ratio. In hydroponic culture, exposure to a diurnal temperature of 33 degrees C increased FC levels in population Calnegre but not in Llano del Beal, compared with plants grown at 22 degrees C; however, high summer temperatures in the field (>30 degrees C) did not coincide with the highest leaf FC levels, since the plants accumulated FCs preferentially in the fruits. Hence, leaf FC levels were higher in winter. Irrigation, to alleviate water stress in the semi-arid conditions, increased the fruit psoralen

concentration but produced only minor decreases in leaf FC levels. There was a significant, positive correlation (P < 0.001) between GSK1904529A research buy the FC and nitrogen concentrations in the plant organs analysed (both increased in the order: fruits > growing leaves > mature leaves), reflecting their respective

contributions to plant fitness. The genetically- and developmentally-regulated accumulation of FCs by B. bituminosa is altered by short-term variations in environmental conditions, particularly temperature. (C) 2012 Elsevier Masson selleck inhibitor SAS. All rights reserved.”
“Hot-electron transport theory of standard semiconductor layered structures predicts the occurrence of negative differential resistance (NDR) associated with inter-valley electron transfer, negative effective mass, and real-space transfer. An analysis of the growth of quantized space-charge waves in single and double heterostructures in which no real-space transfer occurs is presented. It is shown that, in contrast to the situation in bulk material, growth is a complicated function of wavevector because of quantization effects. As a consequence, growth is limited by quantization effects and diffusion to small wave-vectors. To illustrate the effect of quantization clearly, the analysis is limited to growth within the lowest sub-band. In spite of quantization differences, a quantitative comparison can be made by a simple rescaling. Growth is shown to be severely limited to small wave-vectors and its rate turns out to be independent of the details of quantization, being that for extreme confinement.