1,769 research outputs found

    Optical vault: reconfigurable bottle beam by conically refracted light

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    We employ conical refraction of light in a biaxial crystal to create an optical bottle for trapping and manipulation of particles. We show that by just varying the polarization of the input light the bottle can be opened and closed at will. We experimentally demonstrate stable photophoretic trapping and controllable loading and unloading of light absorbing particles in the trap.Comment: 4 pages, 5 figure

    The burden of multiple sclerosis: A community health survey

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    © 2008 Jones et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

    Improving welfare and production in the peri-weaning period: Effects of co-mingling and intermittent suckling on the stress response, performance, behaviour, and gastrointestinal tract carbohydrate absorption in young pigs

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    We investigated the effect of different pre-weaning interventions on performance, aspects of behaviour, and selected neuroendocrine, inflammatory and immune indices in 593 weanling pigs (59 litters, weaning age 22 ± 1.7). Measurements were taken at various time points two weeks before and after weaning. Sugar absorption tests (20% mannitol and 20% galactose solutions) were used to assess gastrointestinal tract (GIT) absorptive capacity. One week before weaning, litters were either co-mingled (CoM) for 8 h daily with another litter or not co-mingled (NoCoM). Half of the litters were also subjected to intermittent suckling (IS) involving separation from their sow for 8 h daily and the other half remained with their sow (NoIS). Hence, four treatments were produced in a 2×2 factorial design; (1) CoM IS (n = 16 litters), (2) CoM NoIS (n = 14 litters), (3) NoCoM IS (n = 16 litters), (4) NoCoM NoIS (n = 13 litters). Measurements are compared within each of the main effects (CoM or IS) unless otherwise stated. Acute weaning stress was evidenced by increases in cortisol, haptoglobin and N: L ratios when data were combined (P < 0.001). However, there were tendencies (P < 0.1) for lower cortisol in IS pigs and higher N: L ratios in CoM pigs at weaning. While CoM did not affect performance before weaning, growth (P < 0.05), feed intake (P < 0.05) and body weight (P < 0.05) were reduced in CoM pigs 7-14 days after weaning. One week of IS before weaning improved feed intake before weaning (P < 0.01), resulting in better growth (P = 0.01) and a tendency (P < 0.1) for a higher feed intake 2-7 days after weaning. Co-mingled piglets had more scratches 4 days before weaning (P < 0.001), but tended to have fewer scratches 2 days after weaning (P < 0.1). Pigs exposed to either IS or CoM displayed more sleeping behaviour the day after weaning (P < 0.01 and P < 0.001). A higher mannitol absorption was evident in CoM NoIS pigs 3 days after weaning (P < 0.01), and galactose absorption was reduced in IS pigs 3 days before weaning (P < 0.05) and tended to be reduced 3 days after weaning (P < 0.1), likely reflecting a GIT adaptive response. Overall, despite improvements in mannitol absorption and behaviour, there was no beneficial effect of CoM on performance after weaning. Alternatively, IS improved behaviour and performance during the first week after weaning

    Structure–Function Mapping: Variability and Conviction in Tracing Retinal Nerve Fiber Bundles and Comparison to a Computational Model

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    yesPurpose: We evaluated variability and conviction in tracing paths of retinal nerve fiber bundles (RNFBs) in retinal images, and compared traced paths to a computational model that produces anatomically-customized structure–function maps. Methods: Ten retinal images were overlaid with 24-2 visual field locations. Eight clinicians and 6 naïve observers traced RNFBs from each location to the optic nerve head (ONH), recording their best estimate and certain range of insertion. Three clinicians and 2 naïve observers traced RNFBs in 3 images, 3 times, 7 to 19 days apart. The model predicted 10° ONH sectors relating to each location. Variability and repeatability in best estimates, certain range width, and differences between best estimates and model-predictions were evaluated. Results: Median between-observer variability in best estimates was 27° (interquartile range [IQR] 20°–38°) for clinicians and 33° (IQR 22°–50°) for naïve observers. Median certain range width was 30° (IQR 14°–45°) for clinicians and 75° (IQR 45°–180°) for naïve observers. Median repeatability was 10° (IQR 5°–20°) for clinicians and 15° (IQR 10°–29°) for naïve observers. All measures were worse further from the ONH. Systematic differences between model predictions and best estimates were negligible; median absolute differences were 17° (IQR 9°–30°) for clinicians and 20° (IQR 10°–36°) for naïve observers. Larger departures from the model coincided with greater variability in tracing. Conclusions: Concordance between the model and RNFB tracing was good, and greatest where tracing variability was lowest. When RNFB tracing is used for structure–function mapping, variability should be considered

    Pre- and post- prandial appetite hormone levels in normal weight and severely obese women

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    <p>Abstract</p> <p>Background</p> <p>Appetite is affected by many factors including the hormones leptin, ghrelin and adiponectin. Ghrelin stimulates hunger, leptin promotes satiety, and adiponectin affects insulin response. This study was designed to test whether the pre- and postprandial response of key appetite hormones differs in normal weight (NW) and severely obese (SO) women.</p> <p>Methods</p> <p>Twenty three women ages 25–50 were recruited for this study including 10 NW (BMI = 23.1 ± 1.3 kg/m<sup>2</sup>) and 13 SO (BMI = 44.5 ± 7.1 kg/m<sup>2</sup>). The study was conducted in a hospital-based clinical research centre. Following a 12-hour fast, participants had a baseline blood draw, consumed a moderately high carbohydrate meal (60% carbohydrate, 20% protein, 20% fat) based on body weight. Postprandially, participants had six blood samples drawn at 0, 15, 30, 60, 90, and 120 minutes. Primary measures included pre- and post-prandial total ghrelin, leptin, adiponectin and insulin. A repeated measures general linear model was used to evaluate the hormone changes by group and time (significance p ≤ 0.05).</p> <p>Results</p> <p>There were significant differences between the NW and the SO for all hormones in the preprandial fasting state. The postprandial responses between the SO versus NW revealed: higher leptin (p < 0.0001), lower adiponectin (p = 0.04), trend for lower ghrelin (p = 0.06) and insulin was not different (p = 0.26). Postprandial responses over time between the SO versus NW: higher leptin (p < 0.001), lower ghrelin and adiponectin (p = 0.004, p = 0.015, respectively), and trend for higher insulin (p = 0.06).</p> <p>Conclusion</p> <p>This study indicates that significant differences in both pre- and selected post- prandial levels of leptin, ghrelin, adiponectin and insulin exist between NW and SO women. Improving our understanding of the biochemical mechanisms accounting for these differences in appetite hormones among individuals with varying body size and adiposity should aid in the development of future therapies to prevent and treat obesity.</p

    Factors Associated with Artificial-Reef Fish Assemblages

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    Visual census (5-min point-count, 100 m2) was used to estimate fish assemblage parameters associated with artificial reef variables from 64 reefs over a 3-yr period in the northern Gulf of Mexico. Dependent variables, recorded by divers [i.e., number of species, number of individuals, length (TL in cm), and species diversity (H\u27)], were analyzed for their associations with potentially underlying environmental attributes using stepwise regression, TWINSPAN, and canonical correspondence analyses (CCA). The fish assemblages (dominated by haemulids, labrids, and serranids) were qualitatively and quantitatively similar to the assemblages described by others from the same general area. Pelagic fishes (carangids and scombrids) associated with the reefs were among the most numerous and were the largest predators in the assemblage. The stepwise regression analysis was able to account for fairly high percentages of the variation in number of species (37%), number of red snapper (43%), and size of red snapper (52%). TWINSPAN allowed the recognition of fish assemblages based on their inshore-offshore biotopes. Vermilion snapper was identified as a key indicator species. The CCA helped identify species groups and factors associated with them. The affinity of pinfish and spottail pinfish with rock jetty was evident, as was the association of triggerfish with vertical steel structure. Although the axis loadings using CCA did not identify a clear species/factor relationship, this analytical method should prove useful in recognizing environmental factors that can be controlled to optimize species-specific artificial reef construction

    The teaching of creativity in information systems programmes at South African higher education institutions

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    The development of problem solving skills is a shared goal in science, engineering, mathematics and technology education. In the applied sciences, problems are often open-ended and complex, requiring a multidisciplinary approach as well as new designs. In such cases, problem solving requires not only analytical capabilities, but also creativity and the ability to innovate. The development of an information system entails problem solving by means of design, hence creativity is integral to the task of an Information Systems (IS) professional. However, it appears that the teaching of creativity in IS programmes is under-researched and possibly neglected. This study investigates what is being done to foster creative ability of South African undergraduate IS students. At the same time, a theoretical framework for creativity teaching is developed. We find that the fostering of creative ability involves more than just the teaching of creativity techniques, and that creativity can be indirectly nurtured in multiple ways.http://www.tandfonline.com/loi/rmse202016-11-30hb201
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