Birefringent dispersive FDTD subgridding scheme

A novel 2D finite difference time domain (FDTD) subgridding method is proposed, only subject to the Courant limit of the coarse grid. By making mu or epsilon inside the subgrid dispersive, unconditional stability is induced at the cost of a sparse, implicit set of update equations. By only adding dispersion along preferential directions, it is possible to dramatically reduce the rank of the matrix equation that needs to be solved

Arsenic in drinking water wells on the Bolivian high plain: field monitoring and effect of salinity on removal efficiency of iron-oxides-containing filters

In the rural areas around Oruro (Bolivia), untreated groundwater is used directly as drinking water. This research aimed to evaluate the general drinking water quality, with focus on arsenic (As) concentrations, based on analysis of 67 samples from about 16 communities of the Oruro district. Subsequently a filter using Iron Oxide Coated Sand (IOCS) and a filter using a Composite Iron Matrix (CIM) were tested for their arsenic removal capacity using synthetic water mimicking real groundwater. Heavy metal concentrations in the sampled drinking water barely exceeded WHO guidelines. Arsenic concentrations reached values up to 964 mu g L-1 and exceeded the current WHO provisional guideline value of 10 mu g L-1 in more than 50% of the sampled wells. The WHO guideline of 250 mg L-1 for chloride and sulphate was also exceeded in more than a third of the samples, indicating high salinity in the drinking waters. Synthetic drinking water could be treated effectively by the IOCS- and CIM-based filters reducing As to concentrations lower than 10 mu g L-1. High levels of chloride and sulphate did not influence As removal efficiency. However, phosphate concentrations in the range from 4 to 24 mg L-1 drastically decreased removal efficiency of the IOCS-based filter but had no effects on removal efficiency of the CIM-based filter. Results of this study can be used as a base for further testing and practical implementation of drinking water purification in the Oruro region

Influences of dietary linoleic acid on coronary flow, left ventricular work, and prostaglandin synthesis in the isolated rat heart

Because of the frequent occurrence of ischemic heart disease, interest in the consequences of dietary fat intake for the heart has increased strongly. and many studies have shown the importance of dietary fat for the heart. Most studies deal with the role of dietary fat in coronary atherosclerosis and the incidence of ischemic or coronary heart disease due to the obstruction of the coronary arteries by atherosclerotic plaques. Several studies have shown that dietary fat can also affect the myocardial muscle cell directly. The best known and most extensive studies in this field are those of essential fatty acid deficienCy and dietary rapeseed oil containing a high amount of erucic acid. Onty few studies on the effects of other dietary fats on the heart. in which athAosclerosis is not involved. have appeared. However. the interest in direct effects of dietary fat on the heart is growing. The final objective of the present study is to gain information about possible favourable and unfavourable properties of dietary fats used for human consumption. The particular objectives of the study were to investigate influences of fats fed to rats for a short period of time on coronary flow rate and external left ventricular work in their isolated. perfused hearts. As the effects found could be ascribed to dietary linoleic acid. which is the ultimate precursor of the prostaglandins of the 1- and 2-series. it was investigated whether prostaglandin synthesis in the isolated heart waS involved. The build-up of the thesis is as follows. Chapter I gives a review of the effects of dietary fat on the heart (excluding atherosclerosis). as well as a review of the differences found in the heart in the oxidation rates and metabolism of various long-chain fatty acids. Chapter 2 contains methods and procedures and a discussion on the use of the isolated. working rat heart for physiological investigations. A discussion on expressing the heart function parameters used per unit of dry heart mass is given in chapter 3. The investigations into the effects of various dietary fats and of prostaglandins in the isolated heart are presented in chapters 4-6 and in the Addenda. Tbe overall discussion on the influences of the dietary fats used on coronary flow rate and external left ventricular work. and on the role of prostaglandins is given in chapter 7

Simulation of Phosphorus Transport in Soil Under Municipal Wastewater Application Using Hydrus-1D

Today, wastewater irrigation is one of the best options to reduce the stress on limited availability of fresh water and to meet the nutrient requirements of crops. In the present study, the simulation accuracy and performance of the HYDRUS-1D model to predict phosphorus leaching have been evaluated and compared to lysimeter data. More specifically, the effects of irrigation using four types of water (wastewater, effluent, mixture of freshwater and effluent, and freshwater) on three types of soil (sandy loam, loam, and clay loam) have been investigated both experimentally and numerically. Barley was planted as a common agricultural crop. The leachates from lysimeters have been collected and sampled at the beginning, middle, and end of the growing season. These samples have then been analyzed for phosphorous. The results show that the trend of change in nutrient concentration (P) was a function of plant requirement. Maximum process of leaching occurred concurrent with minimum plant requirement. The average phosphorus leaching into the root depths turns out to be insignificant, as it amounts to only 0.65–1.65%. This reassuring result means that wastewater with high concentrations of phosphorus compounds (up to 5–10.3 PO4-P mgl−1) can just be treated through an intermittent application to the land surface. Overall, a good agreement between experimental- and numerical-model results is obtained, wherefore the model overestimates the mean phosphate leaching during the growing season of the crop slightly. On the basis of these results, soil with loamy texture was considered to be the most suitable type for irrigation with wastewater and effluent. The results of this research indicate that with a proper management program in regard to the types of soil to be used, crops to be cultivated, water quality, and timing maneuver, the negative impacts of low quality water on soil/plant/groundwater systems can be minimized

Dietary conjugated linoleic acid differentially alters fatty acid composition and increases conjugated linoleic acid content in porcine adipose tissue

Conjugated linoleic acids (CLA) have been shown to decrease body fat content in pigs. It is possible that feeding pigs diets rich in CLA may increase carcass lipid CLA to levels that could provide health benefits when included as a part of a healthy diet. Therefore, the aim of the present study was to determine whether dietary CLA supplementation has any effect on the fatty acid composition of subcutaneous and intramuscular adipose tissue in pigs. Thirty-five female cross bred (Large White X Landrace) pigs (initial weight 57&middot;2 kg and initial P2 back fat 11&middot;5 mm) were used in the present study. Pigs were housed individually and randomly allocated to one of six dietary treatments (0&middot;00, 1&middot;25, 2&middot;50, 5&middot;00, 7&middot;50 and 10&middot;00 g CLA55 (55 g CLA isomers/100 g total fatty acids; Natural Lipids Ltd, Hovdebygda, Norway)/kg)and fed their respective diets for 8 weeks. Twelve CLA isomers in the diet and in pig tissue lipids were separated by Ag&thorn;-HPLC. CLA was incorporated at fivefold higher levels in subcutaneous fat as compared with intramuscular fat and in a dose-dependant manner. Overall, the transfer efficiency of CLA was maximized at 5&middot;00 g CLA55/kg. However, there was clear selectivity in the uptake or incorporation of cis,trans-9,11 isomer over the trans,cis-10,12 isomer. In general, CLA supplementation produced significant changes in skeletal muscle and adipose tissue fatty acid composition, indicating that dietary CLA had a potent affect on lipid transport and metabolism in vivo. Significant increases in myristic, palmitic and palmitoleic acids and a reduction in arachidonic acid were observed, suggesting an alteration inactivity of &Delta;5-, &Delta;6- and &Delta;9-desaturases in pig adipose tissue. In conclusion, feeding pigs diets supplemented with CLA increases carcass lipid CLA, but also results in changes in the fatty acid profile in pig fat that could potentially outweigh the benefits of CLA.<br /