Modelling and performance of a small siphonic hydropower system

A siphon turbine is a low-head, axial-flow hydropower device that can be installed across an impound structure, such as a weir. A laboratory-scale siphon turbine and generator system is built from both off-the-shelf components and bespoke components designed using well-documented guidance. This paper proposes a modelling method for the system, which allows performance to be assessed as a function of operating variables including head, electric load, runner speed and flow rate. An un-modified, commercially available propeller is used for the runner, whose blade geometry is defined within the model as a set of polynomials. This enables flow angles at any radial position on a blade to be determined as a function of the system operating point. Consequently, the impact of design changes on system performance can be quantified, such as part-load efficiency for example. Testing using the laboratory-scale system is conducted up to a maximum gross head of 0.25 m, to validate the component models and then to demonstrate that the final system model provides satisfactory agreement with experiments over the operational speed and head range. The model therefore permits rapid conceptual design to be carried out without the need for computationally intensive co-optimisation of components.     

Subject Choice and Occupational Aspirations among Pupils at Girls' Schools

Various studies have found that British girls' curriculum subject preferences and future aspirations have changed and diversified in recent years. Other work has suggested that girls educated in single-sex schools might have a different (perhaps less gender-stereotypical) experience of education in comparison with their contemporaries at co-educational schools. This article draws on a study of the preferences of girls in English single-sex schools to explore these issues of subject choice and occupational aspiration further. It is argued that, like girls in mixed-sex secondary schools, single-sex schoolgirls' subject preferences have become more diverse and less gender-stereotypical than was the case twenty years ago. But where single-sex schoolgirls might have been expected to rate maths and science more highly than their counterparts in mixed-sex schools, the reverse was the case. Our findings support the argument that girls are now significantly more academically focused and ambitious for their future occupations than they were twenty years ago. However, we argue that a gender dichotomy remains evident in the types of future occupation chosen by girls.     

Effect of the initial dose of foot-and-mouth disease virus on the early viral dynamics within pigs

This paper investigates the early viral dynamics of foot-and-mouth disease (FMD) within infected pigs. Using an existing within-host model, we investigate whether individual variation can be explained by the effect of the initial dose of FMD virus. To do this, we consider the experimental data on the concentration of FMD virus genomes in the blood (viral load). In this experiment, 12 pigs were inoculated with one of three different doses of FMD virus: low; medium; or high. Measurements of the viral load were recorded over a time course of approximately 11 days for every 8 hours. The model is a set of deterministic differential equations with the following variables: viral load; virus in the interstitial space; and the proportion of epithelial cells available for infection, infected and uninfected. The model was fitted to the data for each animal individually and also simultaneously over all animals varying only the initial dose. We show that the general trend in the data can be explained by varying only the initial dose. The higher the initial dose the earlier the development of a detectable viral load.     

Temperature-jump experiments on thin lipid membranes in the presence of valinomycin

Temperature jump relaxation experiments on planar lipid membranes in the presence of valinomycin were performed using the absorption of a strong light flash as an energy source for the generation of the T-jump. The relaxation of the current carried by valinomycin/Rb+ complexes was measured. The results were interpreted on the basis of a transport model which was also analyzed by voltage jump relaxation experiments. The study shows that the application of the T-jump technique provides valuable information about transport kinetics as well as the dynamics of the membrane structure. At the given experimental conditions the relaxation of the current is believed to reflect a temperature-dependent transition of the membrane to a new conformational state of low order. The relaxation could be resolved with the present technique only at low temperatures and for membranes of high microviscosity.     

Peer preferences and social interaction among third-grade children in an integrated school district.

Assessed social interaction among Black and White 3rd-grade children in 9 classrooms. The children were in integrated schools since kindergarten. Two methods were employed: a roster-and-rating sociometric technique and a classroom behavioral observation procedure using sequential time sampling. Sociometric data were obtained for 179 White and 48 Black children. Observational data were obtained for 39 White and 39 Black children. Both race and sex were found to be significant determinants of sociometric ratings for play and work. Omega-squared analyses, however, indicated that sex accounted for 43.2% of the variance on play and 35.2% on work, while race accounted for only about 1% of the variance on each measure. The observational data indicate a positive pattern of classroom interaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Liquid Chromatography–Tandem Mass Spectrometry Multiclass Method for 46 Antibiotics Residues in Milk and Meat: Development and Validation

A screening method for analysis of 46 antibiotics residues, belonging to different classes, such as tetracyclines, sulfonamides, fluoroquinolones, β-lactams, cephalosporins, macrolides and other minority groups was developed and validated for application in bovine milk and bovine, swine, poultry, equine, fish and shrimp meat samples. Sample preparation consists in solvent extraction followed by clean up with C18 bulk and low temperature purification. Instrumental analysis was performed using liquid chromatography coupled to tandem mass spectrometry system. Chromatographic separation was achieved using a C18 column. Mobile phase was composed by methanol and water. The method was validated according to Commission Decision 2002/657/EC criteria. Validation parameters such as specificity and detection capability (CCβ) were determined and considered suitable to the established criteria. Values of CCβ ranged from 1.0 to 50.0 μg L^?1 or μg Kg^?1, depending on the compound and the matrix. The proposed method has been applied into Brazilian National Residue Control Plan since 2013 for the determination of antibiotic residues. A total of 3833 samples were analyzed until the current date and 13 samples showed positive results with concentrations above the permitted. The method is fast, easy and adequate for high throughput analysis in routine laboratories.