The arteriolar vasodilatation model of vibrio cholerae induced diarrhoeal disease

Secretory diarrhoeal disease caused by enterotoxins produced by pathogenic bacteria is characterised by severe fluid loss into the intestine. A prevalent explanation for such high rates of loss, such as occur in episodes of cholera, is that intestinal epithelial cells (enterocytes) actively secrete chloride ion into the lumen. Fluid is drawn into the lumen because of the osmotic pressure difference that is created across the mucosa. Widely proposed as the cause of many forms of secretory diarrhoea, the enterocyte based paradigm displaced an earlier model of secretion i.e. fluid filtration caused by increased capillary hydrostatic pressure, possibly coupled with increased hydraulic conductivity. This would be aggravated by any concurrent inhibition of fluid absorption if it occurred. In the earlier and alternative paradigm, pathophysiological reductions in smooth muscle tone elevate capillary pressure, thereby increasing the hydrostatic pressure gradient that forces fluid from the capillary into the interstitial space and thence into the lumen. In this review, the present and historical evidence for the vasodilatation view of secretory diarrhoeal disease is presented, together with past challenges of this concept, particularly those involving the erroneous equating of solute permeability with hydraulic conductivity. It can be seen that the physical forces model of altered Starling forces combined with enhanced fluid permeation explains more experimental findings than the cellular based enterocyte model can. Several key past papers advocating enterocyte secretion in which the capillary vasodilatation model was also discounted, were examined for the inherent fallacies within the arguments that were proposed. Where possible, quantitative arguments are proposed that indicate that is it the combination of capillary vasodilatation combined with increased tight junctional hydraulic conductivity that causes profuse secretion, made worse by any concurrent inability to absorb fluid. To assist the general physiological reader, an appendix reviews Bernoulli’s principle of flow within tubes and explains the arguably counter-intuitive phenomenon that vasodilatation increases capillary pressure because of a velocity reduction within a dilated segment

Technology Mapping for Circuit Optimization Using Content-Addressable Memory

The growing complexity of Field Programmable Gate Arrays (FPGA's) is leading to architectures with high input cardinality look-up tables (LUT's). This thesis describes a methodology for area-minimizing technology mapping for combinational logic, specifically designed for such FPGA architectures. This methodology, called LURU, leverages the parallel search capabilities of Content-Addressable Memories (CAM's) to outperform traditional mapping algorithms in both execution time and quality of results. The LURU algorithm is fundamentally different from other techniques for technology mapping in that LURU uses textual string representations of circuit topology in order to efficiently store and search for circuit patterns in a CAM. A circuit is mapped to the target LUT technology using both exact and inexact string matching techniques. Common subcircuit expressions (CSE's) are also identified and used for architectural optimization---a small set of CSE's is shown to effectively cover an average of 96% of the test circuits. LURU was tested with the ISCAS'85 suite of combinational benchmark circuits and compared with the mapping algorithms FlowMap and CutMap. The area reduction shown by LURU is, on average, 20% better compared to FlowMap and CutMap. The asymptotic runtime complexity of LURU is shown to be better than that of both FlowMap and CutMap

An investigation into the relationship between small intestinal fluid secretion and systemic arterial blood pressure in the anesthetized rat

In the absence of an ability to absorb fluid by cellular uptake mechanisms, fluid movement in vivo from the perfused rat intestine is absorptive when the diastolic blood pressure is normal or very low but is secretory when blood pressure falls below normal. This pattern of fluid movement is consistent with changes in capillary pressure within the villus. Whether flow moves into or out of the intestine is determined by changes in the Starling forces across intestinal capillaries. These observations indicate that secretion caused by some bacterial enterotoxins may act solely on the vasculature of the small intestine. This contradicts a major current theory of secretion that requires the source of the fluid to be from the epithelial cell. The significance of this work is that the intestinal arterioles rather than the epithelial cells may determine secretion. If substantiated, this may allow the development of the effective anti-secretory drugs that have not been forthcoming with development strategies based on the enterocyte model of deranged intestinal secretion

Small and medium sized enterprises (SMEs) and their cost of capital

Existing finance literature is inadequate with respect to its coverage of the capital structure of small and medium sized enterprises (SMEs). This lack of coverage means that SMEs are provided with little or no guidance for optimising their cost of capital. This paper is an attempt to provide such guidance. For unlisted SMEs the cost of equity cannot be derived from the capital market, nor can it be ascertained by asking the entrepreneurs, since their decision to invest is usually driven by many other factors, over and above the simple (financial) return on investment requirement. A further problem in quantifying cost of equity results from the fact that entrepreneurs can be asked to provide additional (informal) investment in the form of personal guarantees. We put forward a model that attempts to solve these problems. Firstly, our model determines a 'legitimate' expected return for the entrepreneur, by considering the probability of liquidation of the venture and the loss incurred by the entrepreneur in this event. The former can be derived by looking at the specific survival rate of firms; the latter, is based on how much the potential bankruptcy affects the wealth of the entrepreneur. Secondly, we suggest taking into consideration the personal collateral provided by the entrepreneur, as if it were additional equity invested in the venture. To calculate such an amount, we suggest taking into account only the amount of collateralised debt that cannot be covered by the revenue from the sales of the firm's assets in case of liquidation

Production Practices of Arkansas Beef Cattle Producers

This report contains information from a 1996 survey on production practices of Arkansas beef cattle producers. While several studies have been completed on the profitability of retained ownership of beef cattle, few empirical data are available on production practices of cow/calf and stocker operations in Arkansas. This report shows that there are some differences in production methods across operation types. Further, the report summarizes demographic characteristics of Arkansas cow/calf and stocker operations. The results of this study can be particularly helpful in providing the needed data for studying the potential economic impact of feeding weaned calves to heavier weights in Arkansas as a value-added production alternative to selling calves at weaning. It should also prove helpful in the formulation of budgets and simulation models

Collaborative Collective Algorithms to Coordinate UGVs

Sentel/Brilliant Innovations has developed autonomous UGVs (unmanned ground vehicles) capable of generating a map of an unknown location through exploration using local software and the power of Google Tango technology. This project was tasked with developing an efficient and capable map-stitching solution allowing multiple UGVs to coordinate their movements and share information in order to greatly improve the speed at which these drones can be used to generate maps. The solution utilizes the processing power of a Raspberry Pi to pull maps from a Redis server and stitch them together. Once stitched, the maps are redistributed via the Redis server back through the network, providing every UGV the opportunity to obtain the global map. All of this stitching is performed on a single UGV, freeing the other drones to focus on generating and uploading their own unique maps to the server. The drones can use this new information to better inform their next move to prevent multiple drones from generating a map of the same location. In the future, Sentel/Brilliant Innovations hopes to take this technology and attach more advanced sensors to the drones, allowing them to add greater detail of the environment to the map rather than simply drawing boundaries. These drones have many potential applications, such as search and rescue, seeking out potential hazards, and intelligence for military and civil use.https://scholarscompass.vcu.edu/capstone/1187/thumbnail.jp

Financing SMEs: a model for optimising the capital structure

This paper argues that the existing finance literature is inadequate with respect to its cov-erage of capital structure of small and medium sized enterprises (SMEs). In particular it is argued that the cost of equity (being both conceptually ill defined and empirically non quantifiable) is not applicable to the capital structure decisions for a large proportion of SMEs and the optimal capital structure depends only on the mix of short and long term debt. The paper then presents a model for optimising the debt mix and demonstrates its practical application using an Italian firm’s debt structure as a case study