Mammary blood flow and metabolic activity are linked by a feedback mechanism involving nitric oxide synthesis

To test which, if any, of the major milk precursors can elicit a rapid change in the rate of mammary blood flow (MBF) and to define the time course and magnitude of such changes, 4 lactating cows were infused with glucose, amino acids, or triacylglycerol into the external iliac artery feeding one udder half while iliac plasma flow (IPF) was monitored continuously by dye dilution. Adenosine and saline were infused as positive and negative controls, respectively, and insulin was infused to characterize the response to a centrally produced anabolic hormone. To test the roles of cyclooxygenase, NO synthase and ATP-sensitive K (K) channels in nutrient-mediated changes in blood flow, their respective inhibitors-indomethacin, N-nitro-L-arginine methyl ester hydrochloride (L-NAME), and glibenclamide-were infused simultaneously with glucose. Each day, 1 infusate was given twice to each cow, over a 20-min period each time, separated by a 20-min washout period. In addition, each treatment protocol was administered on 2 separate days. A 73% increase in IPF during adenosine infusion showed that the mammary vasodilatory response was quadratic in time, with most changes occurring in the first 5min. Glucose infusion decreased IPF by 9% in a quadratic manner, most rapidly in the first 5min, indicating that a feedback mechanism of local blood flow control, likely through adenosine release, was operative in the mammary vasculature. Amino acid infusion increased IPF 9% in a linear manner, suggesting that mammary ATP utilization was stimulated more than ATP production. This could reflect a stimulation of protein synthesis. Triacylglycerol only tended to decrease IPF and insulin did not affect IPF. A lack of IPF response to glibenclamide indicates that K channels are not involved in MBF regulation. Indomethacin and L-NAME both depressed IPF. In the presence of indomethacin, glucose infusion caused a quadratic 9% increase in IPF. Indomethacin is an inhibitor of mitochondrial function, so the glucose-induced increase in IPF was interpreted as feedback on mammary adenosine release from an anabolic response to glucose. Because NO synthase was not inhibited during indomethacin infusion, the feedback system is postulated to act through endothelial NO synthase. In the presence of L-NAME, glucose infusion had no effect on IPF, indicating that endothelial cyclooxygenase is not involved in glucose-induced changes in MBF

Kafirin structure and functionality

The structural and functional properties of kafirins are reviewed. Three classes of kafirin: the a, ß and ? forms have been identified at the protein level and one, the d, has been identified only at the gene and transcript levels. All forms show high homology with the equivalent zein proteins. By analogy with the zeins it is believed that the a-kafirins probably have an extended hairpin structure in solution, comprising elements of a-helix, ß-sheet and turns folded back on itself. Kafirins are the most hydrophobic of the prolamins as shown by their solubility, and calculated hydration free energies. The proteins exhibit extensive cross-linking by disulphide bonds and on cooking form indigestible aggregates which are not solubilised by reduction of disulphide bonds. In spite of continuing studies, the reasons for the low digestibility of the protein remain uncertain and there may be several factors involved. Other research has shown that kafirins may have non-food uses and may be used to form films

The roles of the formal and informal sectors in the provision of effective science education

For many years, formal school science education has been criticised by students, teachers, parents and employers throughout the world. This article presents an argument that a greater collaboration between the formal and the informal sector could address some of these criticisms. The causes for concern about formal science education are summarised and the major approaches being taken to address them are outlined. The contributions that the informal sector currently makes to science education are identified. It is suggested that the provision of an effective science education entails an enhanced complementarity between the two sectors. Finally, there is a brief discussion of the collaboration and communication still needed if this is to be effective

The economic value of conditioning harvest start date on long-lead seasonal climate forecasts

Seasonal climate forecasts can now predict climate with significant skill and lead times in the major cane growing regions of Australia. However, despite these meteorological advancements relatively little research has examined the 'on-the-ground economic impact of these forecasts. This lack of quantitative knowledge creates an atmosphere of uncertainty about whether cane growers should alter their behaviour in response to the forecast. To address this issue, we developed an agronomic-economic model of the average cane farm the Herbert River District to determine the economic value of scheduling the annual harvest start date based on seasonal climate forecasts. Results indicate that the value of seasonal forecasts when used in this manner is modest with respect to the farmer's annual profits. The central limiting factor appears to be the reasonably high degree of climatic variability that can still occur within each climate phase predicted by the forecast.The forecast value is also dependent on soil type and therefore likely to be highly variable spatially. This highlights the need to better understand how the forecast would be communicated and changes implemented within the context of the harvest scheduling framework and other farm management decisions

The economic value of conditioning harvest start date\ud on long-lead seasonal climate forecasts

Seasonal climate forecasts can now predict climate with significant skill and lead times in the major cane growing regions of Australia. However, despite these meteorological advancements relatively little research has examined the 'on-the-ground economic impact of these forecasts. This lack of quantitative knowledge creates an atmosphere of uncertainty about whether cane growers should alter their behaviour in response to the forecast. To address this issue, we developed an agronomic-economic model of the average cane farm the Herbert River District to determine the economic value of scheduling the annual harvest start date based on seasonal climate forecasts. Results indicate that the value of seasonal forecasts when used in this manner is modest with respect to the farmer's annual profits. The central limiting factor appears to be the reasonably high degree of climatic variability that can still occur within each climate phase predicted by the forecast.The forecast value is also dependent on soil type and therefore likely to be highly variable spatially. This highlights the need to better understand how the forecast would be communicated and changes implemented within the context of the harvest scheduling framework and other farm management decisions

Computing Nash equilibria through computational intelligence methods

Nash equilibrium constitutes a central solution concept in game theory. The task of detecting the Nash equilibria of a finite strategic game remains a challenging problem up-to-date. This paper investigates the effectiveness of three computational intelligence techniques, namely, covariance matrix adaptation evolution strategies, particle swarm optimization, as well as, differential evolution, to compute Nash equilibria of finite strategic games, as global minima of a real-valued, nonnegative function. An issue of particular interest is to detect more than one Nash equilibria of a game. The performance of the considered computational intelligence methods on this problem is investigated using multistart and deflection