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We have previously demonstrated that dopamine agonist, SKF38396 (SKF), can substitute for progesterone in the facilitation of female reproductive behaviour in oestradiol benzoate-primed female rats and mice. We also reported that both progesterone- and SKF-initiated signalling were mediated by the cAMP-dependent protein kinase A signal transduction cascade. As the rapid effects of progesterone are also mediated by calcium-dependent kinases, calcium- and calmodulin-dependent kinase (CaMKII) and protein kinase (PKC), we sought to determine whether SKF-initiated signalling also recruited calcium as a second messenger. We measured the changes in the activation of CaMKII and PKC in the ventromedial nucleus (VMN) of the hypothalamus and preoptic area (POA) of the rat brain, which are the two regions implicated in the regulation of female reproductive behaviour in rodents. We measured the basal activities representing the activation of the kinases by in vivo treatments, as well as the total kinase activities assayed in the presence of exogenous cofactors in vitro. We report that, in contrast to progesterone-initiated signalling, there was no recruitment of calcium by SKF in the hypothalamus, as shown by the absence of changes in CaMKII activities in the VMN and POA. Furthermore, SKF-treatment resulted in a rapid increase in calcium-independent basal PKC activity in the VMN but not the POA. These rapid changes were not the result of changes in PKC protein levels or phosphorylation status. These data indicate that progesterone- and SKF-recruit distinct signalling molecules within the same regions of the brain to activate region-specific signal transduction pathways.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 944-946, GaAsN materials grown by chemical beam epitaxy (CBE) were investigated, as a preliminary step to realizing super-high efficiency four junction solar cells. We achieved the reduction of residual impurity concentration by chemical reaction control on the growing surface by modifying flow sequence of precursors and by increasing step density on the surface by using a vicinal GaAs substrate. Furthermore, the improvement in carrier mobility was observed, and it was suggested that the reduction of both residual impurities and N-related defects leads this improvement. The residual acceptor concentration is also decreased by decreasing residual impurities, and n-type doping was enabled. We have successfully controlled electron concentration from 1015 to 1018 cm–3 by Si doping using a SiH4 gas. Based on these results GaAsN homo-junction solar cells were fabricated by CBE.

The paper presents the results of an optimization study of an automotive fuel cell propulsion system equipped with a fuel reformer. Based on a set of fuel cell polarization curves determined experimentally by running a prototype fuel cell stack at a variety of operating pressures and temperatures, a numerical steady state model was used to determine the optimal operating pressure and temperature. The optimization criteria were the size of individual components and the entire propulsion system as well as its total efficiency at both full power and partial load. The results suggested that an automotive system should be operated at relatively high pressure (308 kPa), but an expander must be used to recover most of the power used for compression. A surprising result of this analysis is that a relatively low temperature (∼60°C) results in smallest heat rejection equipment if neutral water balance is mandated. The efficiency of the system is about 33% at full power and about 38% at 25% of the load. Higher efficiencies may be achieved by selecting a higher fuel cell operating voltage, but that would result in larger fuel cell stacks, which may be a limiting factor for automotive application with the state-of-the-art fuel cells.

This article 'Biological Studies of the Population Dynamics of Rice Brown Planthopper and Green Leafhopper' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.

The objective of this paper is to provide a general overview on optimizing a PEM fuel cell system for backup power applications based on a set of key input and design parameters such as temperature, pressure, humidification, water management, and cell voltage. Low temperature and low pressure is beneficial for system simplicity and efficiency. It is possible to relax water management and humidification requirements at low pressures by selecting low operating temperatures. Higher selected nominal cell voltage does not necessarily mean higher operating efficiency particularly if the stack is operated at partial loads most of the time. So selection of nominal cell voltage must be based collectively on factors such as cost of the stack, cost of fuel consumed, load profile and capacity factor, lifetime, etc.

The paper presents the results of an optimization study of an automotive fuel cell propulsion system equipped with a fuel reformer. Based on a set of fuel cell polarization curves determined experimentally by running a prototype fuel cell stack at a variety of operating pressures and temperatures, a numerical steady state model was used to determine the optimal operating pressure and temperature. The optimization criteria were the size of individual components and the entire propulsion system as well as its total efficiency at both full power and partial load. The results suggested that an automotive system should be operated at relatively high pressure (308 kPa), but an expander must be used to recover most of the power used for compression. A surprising result of this analysis is that a relatively low temperature (~60°C) results in smallest heat rejection equipment if neutral water balance is mandated. The efficiency of the system is about 33% at full power and about 38% at 25% of the load. Higher efficiencies may be achieved by selecting a higher fuel cell operating voltage, but that would result in larger fuel cell stacks, which may be a limiting factor for automotive application with the state-of-the-art fuel cells.