1,002 research outputs found

    A globally accurate theory for a class of binary mixture models

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    Using the self-consistent Ornstein-Zernike approximation (SCOZA) results for the 3D Ising model, we obtain phase diagrams for binary mixtures described by decorated models. We obtain the plait point, binodals, and closed-loop coexistence curves for the models proposed by Widom, Clark, Neece, and Wheeler. The results are in good agreement with series expansions and experiments.Comment: 16 pages, 10 figure

    Investigation of prediction methods for the loads and stresses of Apollo type spacecraft parachutes. Volume 1: Loads

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    An analysis was conducted with the objective of upgrading and improving the loads, stress, and performance prediction methods for Apollo spacecraft parachutes. The subjects considered were: (1) methods for a new theoretical approach to the parachute opening process, (2) new experimental-analytical techniques to improve the measurement of pressures, stresses, and strains in inflight parachutes, and (3) a numerical method for analyzing the dynamical behavior of rapidly loaded pilot chute risers

    Up-scaling orange-fleshed sweetpotato (Ipomoea batatas (L) Lam) technologies in western Kenya.

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    Vitamin A deficiency is a major nutritional problem in Kenya, leading to night blindness and high mortality rate in infants. Consumption of orange-fleshed sweetpotato (OFSP) that is high in -carotene (pro-vitamin A), can reduce the risk of the deficiency. The utilization of the OFSP in Kenya despite its nutritional advantage is limited. Efforts by the Government extension service to promote the crop has had limited impact. The Kenya Agricultural Research Institute in collaboration with the International Potato Centre and farmers developed a number of OFSP technologies that can enhance its utilization. The ASARECA/AfDB-supported project “Dissemination of New Agricultural Technologies in Africa” (DONATA) for Orange-fleshed sweetpotato (OFSP) was initiated in Bungoma and Busia counties of Western Kenya in 2008. The project used the Innovation Platforms for Technology Adoption (IPTAs) approach in up-scale the proven OFSP technologies. IPTA acts as the institutional mechanism bringing together different stakeholders for scaling out and scaling-up of OFSP technologies along the value chain. Within three years 29 technologies on seed systems, agronomic practises, postharvest processing and marketing were promoted to 7500 beneficiaries. This was achieved through training of 215 extension agents and 1250 farmers on different aspects of OFSP. Thirteen information products were made available to the users through 15 different uptake pathways. Area under OFSP root production increased by over 600% while productivity per unit area increased from 8 to 16 tons/ha in the project countie

    Solar feature tracking in both spatial and temporal domains

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    A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. The reliability of this technique was tested with TRACE 171A observations. The application of this technique to a flare-induced kink-mode oscillation, revealed a 3500 km spatial periodicity which occur along the loop edge. We establish a reduction in oscillatory power, for these spatial periodicities, of 45% over a 322 s interval. We relate the reduction in oscillatory power to the physical damping of these loop-top oscillations

    Effect of seasonal diet composition changes on the characteristics of the gastrointestinal tract contents of the Eurasian beaver (Castor fiber).

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    The goal of the study was to compare chemical and physical parameters of the content of various gastrointestinal (GI) tract segments of adult beavers and to relate the obtained results to seasonal changes in the composition of natural diet. The study was conducted on 36 adult beavers originated from the natural environment that were captured in winter, summer and autumn. The obtained results demonstrated that pH, redox potential (Eh), dry matter (DM), short-chain fatty acids (SCFA) and distribution of food particles varied along the beaver GI tract during the year. The lowest value of pH was observed in stomach whereas the highest in the small intestine and cecum. The reverse pattern of changes was found for the value of redox potential. The research indicated that anaerobic conditions were predominant in the cecum and so contributed to development of microbial population. Also, the increase in the SCFA contents in the cecum and colon indicated that beavers belong both to hindgut fermenters as well as to the mixed moderate type animals. In summary, the obtained results indicated that seasonal changes in the diet composition affected physical and chemical parameters as well as microbial activity of the GI tract of beaver

    On the period ratio P<sub>1</sub>/2P<sub>2</sub> in the oscillations of coronal loops

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    &lt;p&gt;Aims. With strong evidence of fast and slow magnetoacoustic modes arising in the solar atmosphere there is scope for improved determinations of coronal parameters through coronal seismology. Of particular interest is the ratio P&lt;sub&gt;1&lt;/sub&gt;/2P&lt;sub&gt;2&lt;/sub&gt;between the period P&lt;sub&gt;1&lt;/sub&gt; of the fundamental mode and the period P&lt;sub&gt;2&lt;/sub&gt; of its first harmonic; in an homogeneous medium this ratio is one, but in a more complex configuration it is shifted to lower values.&lt;/p&gt; &lt;p&gt;Methods. We consider analytically the effects on the different magnetohydrodynamic modes of structuring and stratification, pointing out that transverse or longitudinal structuring or gravitational stratification modifies the ratio P&lt;sub&gt;1&lt;/sub&gt;/2P&lt;sub&gt;2&lt;/sub&gt;.&lt;/p&gt; &lt;p&gt;Results. The deviations caused by gravity and structure are studied for the fast and slow modes. Structure along the loop is found to be the dominant effect.&lt;/p&gt; &lt;p&gt;Conclusions. The departure of P&lt;sub&gt;1&lt;/sub&gt;/2P&lt;sub&gt;2&lt;/sub&gt; from unity can be used as a seismological tool in the corona. We apply our technique to the observations by Verwichte et al. (2004), deducing the density scale height in a coronal loop.&lt;/p&gt

    Saltation transport on Mars

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    We present the first calculation of saltation transport and dune formation on Mars and compare it to real dunes. We find that the rate at which grains are entrained into saltation on Mars is one order of magnitude higher than on Earth. With this fundamental novel ingredient, we reproduce the size and different shapes of Mars dunes, and give an estimate for the wind velocity on Mars.Comment: 4 pages, 3 figure

    Do South African international cricket pace bowlers have similar bowling volume and injury risk associates compared to other elite fast bowlers?

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    BACKGROUND While many cricket-playing nations have conducted research on bowling volume (BV) and injury risk, this relationship among international South African pace bowlers is yet to be investigated. Environmental, socio-economic, and training strategy differences warrant similar research in a South African context. The purpose of this preliminary study was to establish if South African pace bowlers have similar bowling volume and injury associates compared to other elite fast bowlers. METHODS This study was a prospective, observational, cohort study that monitored match and training BV and injuries among pace bowlers playing for the South African national team between April 2017 and April 2019. A sample of convenience that included fourteen bowlers was selected. Bowling volume was quantified as the number of deliveries bowled during training and competition. Acute-, chronic- and acute: chronic bowling volume ratios were independently modeled as association variables. RESULTS There were 39 injuries with the most being to the lumbar spine (25.64%). Moderate-to-low and a moderate-to-high acute: chronic bowling load ratios were associated with a lower risk of injury. Chronic bowling load was associated with injury (z = 2.82, p = 0.01). A low acute workload, low chronic workload, moderate-high chronic workload, and moderate-low acute: chronic ratio was also associated with an increased risk of injury. CONCLUSION These findings confirm that there appears to be a dose-response effect between training bowling volume and the likelihood of an injury occurring with a moderate-to-low and a moderate-to-high bowling volume ratio being optimal. Considering the small sample size, the findings should be interpreted with caution

    Short-wave infrared barriode detectors using InGaAsSb absorption material lattice matched to GaSb

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    Short-wave infrared barriode detectors were grown by molecular beam epitaxy. An absorption layer composition of In0.28Ga0.72As0.25Sb0.75 allowed for lattice matching to GaSb and cut-off wavelengths of 2.9 μm at 250 K and 3.0 μm at room temperature. Arrhenius plots of the dark current density showed diffusion limited dark currents approaching those expected for optimized HgCdTe-based detectors. Specific detectivity figures of around 7×1010 Jones and 1×1010 Jones were calculated, for 240 K and room temperature, respectively. Significantly, these devices could support focal plane arrays working at higher operating temperatures
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