An isotope dilution model for partitioning of phenylalanine and tyrosine uptake by the liver of lactating dairy cows

An isotope dilution model to describe the partitioning of phenylalanine (PHE) and tyrosine (TYR) in the bovine liver was developed. The model comprises four intracellular and six extracellular pools and various flows connecting these pools and external blood. Conservation of mass principles were applied to generate the fundamental equations describing the behaviour of the system in the steady state. The model was applied to datasets from multi-catheterised dairy cattle during a constant infusion of [1-13C] phenylalanine and [2,3,5,6-2H] tyrosine tracers. Model solutions described the extraction of PHE and TYR from the liver via the portal vein and hepatic artery. In addition, the exchange of free PHE and TYR between extracellular and intracellular pools was explained and the hydroxylation of PHE to TYR was estimated. The model was effective in providing information about the fates of PHE and TYR in the liver and could be used as part of a more complex system describing amino acid metabolism in the whole animal

A mechanistic model of small intestinal starch digestion and glucose uptake in the cow

The high contribution of postruminal starch digestion (up to 50%) to total-tract starch digestion on energy-dense, starch-rich diets demands that limitations to small intestinal starch digestion be identified. A mechanistic model of the small intestine was described and evaluated with regard to its ability to simulate observations from abomasal carbohydrate infusions in the dairy cow. The 7 state variables represent starch, oligosaccharide, glucose, and pancreatic amylase in the intestinal lumen, oligosaccharide and glucose in the unstirred water layer at the intestinal wall, and intracellular glucose of the enterocyte. Enzymatic hydrolysis of starch was modeled as a 2-stage process involving the activity of pancreatic amylase in the lumen and of oligosaccharidase at the brush border of the enterocyte confined within the unstirred water layer. The Na+-dependent glucose transport into the enterocyte was represented along with a facilitative glucose transporter 2 transport system on the basolateral membrane. The small intestine is subdivided into 3 main sections, representing the duodenum, jejunum, and ileum for parameterization. Further subsections are defined between which continual digesta flow is represented. The model predicted nonstructural carbohydrate disappearance in the small intestine for cattle unadapted to duodenal infusion with a coefficient of determination of 0.92 and a root mean square prediction error of 25.4%. Simulation of glucose disappearance for mature Holstein heifers adapted to various levels of duodenal glucose infusion yielded a coefficient of determination of 0.81 and a root mean square prediction error of 38.6%. Analysis of model behavior identified limitations to the efficiency of small intestinal starch digestion with high levels of duodenal starch flow. Limitations to individual processes, particularly starch digestion in the proximal section of the intestine, can create asynchrony between starch hydrolysis and glucose uptake capacity

Security and Privacy as Hygiene Factors of Developer Behavior in Small and Agile Teams

Part 3: Peace, War, Cyber-Security and ICTInternational audienceUser motivations are often considered in human computer relations. The analysis of developer behavior often lacks this perspective. Herzberg’s distinction of motivators and hygiene factors adds a level for the analyses of those sociotechnical phenomena that lead to skipping of security and privacy requirements especially in agile development projects. Requirements of security and privacy are not considered nice-to-have, but as necessary hygiene factors of systems attractiveness, motivation for extra effort is low with respect to those requirements. The motivators for developers – functionality that makes a system special and which is valued by customers and users are dominant for the decisions about priorities of development – hygiene factors like many security requirements get a lower priority. In this paper we introduce this theory with relation to known problems of (agile) development projects with respect to implementing security and privacy. We present this with a case study of mobile app development in a research project that we analyzed by security and privacy aspects

The economic impact of major sports events : a review of ten events in the UK

Over recent years there has been a marked contrast between the discussions around the economic impact of major sports events in North America on the one hand and most of the rest of the world on the other. In the USA the sports strategies of cities in the USA have largely been based on infrastructure (stadium) investment for professional team sports, in particular, American football, baseball, basketball, and ice hockey. Over the last decade cities have offered greater and greater incentives for these professional teams to move from their existing host cities by offering to build a new stadium to house them. The teams sit back and let the host and competing cities bid up the price. They either move to the city offering the best deal or they accept the counter offer invariably put to them by their existing hosts. This normally involves the host city building a brand new stadium to replace the existing one which may only be ten or fifteen years old. The result is that at the end of the 1990s there were thirty major stadium construction projects in progress, around one-third of the total professional sports infrastructure, but over half of all professional teams in the USA have expressed dissatisfaction with their current facilities