287 research outputs found

    Energy cost and return for hunting in African wild dogs and Cheetahs

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    African wild dogs (Lycaon pictus) are reported to hunt with energetically costly long chase distances. We used high-resolution GPS and inertial technology to record 1,119 high-speed chases of all members of a pack of six adult African wild dogs in northern Botswana. Dogs performed multiple short, high-speed, mostly unsuccessful chases to capture prey, while cheetahs (Acinonyx jubatus) undertook even shorter, higher-speed hunts. We used an energy balance model to show that the energy return from group hunting and feeding substantially outweighs the cost of multiple short chases, which indicates that African wild dogs are more energetically robust than previously believed. Comparison with cheetah illustrates the trade-off between sheer athleticism and high individual kill rate characteristic of cheetahs, and the energetic robustness of frequent opportunistic group hunting and feeding by African wild dogs

    Analysis of the seismic performance of a two storey log house

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    The dearth of knowledge on the load resistance mechanisms of log houses and the need for developing numerical models that are capable of simulating the actual behaviour of these structures has pushed efforts to research the relatively unexplored aspects of log house construction. The aim of the research that is presented in this paper is to build a working model of a log house that will contribute toward understanding the behaviour of these structures under seismic loading. The paper presents the results of a series of shaking table tests conducted on a log house and goes on to develop a numerical model of the tested house. The finite element model has been created in SAP2000 and validated against the experimental results. The modelling assumptions and the difficulties involved in the process have been described and, finally, a discussion on the effects of the variation of different physical and material parameters on the results yielded by the model has been drawn up.The research leading to these results has received funding from the European Union‘s Seventh Framework Programme [FP7/2007-2013] under grant agreement n°227887 (SERIES)

    Drinking beer, wine or spirits – does it matter for inequalities in alcohol-related hospital admission? A record-linked longitudinal study in Wales

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    Background: Alcohol-related harm has been found to be higher in disadvantaged groups, despite similar alcohol consumption to advantaged groups. This is known as the alcohol harm paradox. Beverage type is reportedly socioeconomically patterned but has not been included in longitudinal studies investigating record-linked alcohol consumption and harm. We aimed to investigate whether and to what extent consumption by beverage type, BMI, smoking and other factors explain inequalities in alcohol-related harm. Methods: 11,038 respondents to the Welsh Health Survey answered questions on their health and lifestyle. Responses were record-linked to wholly attributable alcohol-related hospital admissions (ARHA) eight years before the survey month and until the end of 2016 within the Secure Anonymised Information Linkage (SAIL) Databank. We used survival analysis, specifically multi-level and multi-failure Cox mixed effects models, to calculate the hazard ratios of ARHA. In adjusted models we included the number of units consumed by beverage type and other factors, censoring for death or moving out of Wales. Results: People living in more deprived areas had a higher risk of admission (HR 1.75; 95% CI 1.23–2.48) compared to less deprived. Adjustment for the number of units by type of alcohol consumed only reduced the risk of ARHA for more deprived areas by 4% (HR 1.72; 95% CI 1.21–2.44), whilst adding smoking and BMI reduced these inequalities by 35.7% (HR 1.48; 95% CI 1.01–2.17). These social patterns were similar for individual-level social class, employment, housing tenure and highest qualification. Inequalities were further reduced by including either health status (16.6%) or mental health condition (5%). Unit increases of spirits drunk were positively associated with increasing risk of ARHA (HR 1.06; 95% CI 1.01–1.12), higher than for other drink types. Conclusions: Although consumption by beverage type was socioeconomically patterned, it did not help explain inequalities in alcohol-related harm. Smoking and BMI explained around a third of inequalities, but lower socioeconomic groups had a persistently higher risk of (multiple) ARHA. Comorbidities also explained a further proportion of inequalities and need further investigation, including the contribution of specific conditions. The increased harms from consumption of stronger alcoholic beverages may inform public health policy

    Singlet oxygen luminescence as an in vivo photodynamic therapy dose metric: validation in normal mouse skin with topical amino-levulinic acid

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    Although singlet oxygen (1O2) has long been proposed as the primary reactive oxygen species in photodynamic therapy (PDT), it has only recently been possible to detect it in biological systems by its luminescence at 1270 nm. Having previously demonstrated this in vitro and in vivo, we showed that cell survival was strongly correlated to the 1O2 luminescence in cell suspensions over a wide range of treatment parameters. Here, we extend this to test the hypothesis that the photobiological response in vivo is also correlated with 1O2 generation, independent of individual treatment parameters. The normal skin of SKH1-HR hairless mice was sensitised with 20% amino-levulinic acid-induced protoporophyrin IX and exposed to 5, 11, 22 or 50 J cm−2 of pulsed 523 nm light at 50 mW cm−2, or to 50 J cm−2 at 15 or 150 mW cm−2. 1O2 luminescence was measured during treatment and the photodynamic response of the skin was scored daily for 2 weeks after treatment. As observed by other authors, a strong irradiance dependence of the PDT effect was observed. However, in all cases the responses increased with the 1O2 luminescence, independent of the irradiance, demonstrating for the first time in vivo an unequivocal mechanistic link between 1O2 generation and photobiological response

    Study of thin film poly-crystalline CdTe solar cells presenting high acceptor concentrations achieved by in-situ arsenic doping

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    Doping of CdTe using Group-V elements (As, P, and Sb) has gained interest in pursuit of increasing the cell voltage of CdTe thin film solar devices. Studies on bulk CdTe crystals have shown that much higher acceptor concentration than the traditional copper treatment is possible with As, P or Sb, enabled by high process temperature and/or rapid thermal quenching under Cd overpressure. We report a comprehensive study on in-situ As doping of poly-crystalline CdTe solar cells by MOCVD, whereby high acceptor densities, approaching 3 × 1016 cm−3 were achieved at low growth temperature of 390 °C. No As segregation could be detected at grain boundaries, even for 1019 As cm−3. A shallow acceptor level (+0.1 eV) due to AsTe substitutional doping and deep-level defects were observed at elevated As concentrations. Devices with variable As doping were analysed. Narrowing of the depletion layer, enhancement of bulk recombination, and reduction in device current and red response, albeit a small near infrared gain due to optical gap reduction, were observed at high concentrations. Device modelling indicated that the properties of the n-type window layer and associated interfacial recombination velocity are highly critical when the absorber doping is relatively high, demonstrating a route for obtaining high cell voltage

    Habitual Physical Activity in Mitochondrial Disease

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    Mitochondrial disease is the most common neuromuscular disease and has a profound impact upon daily life, disease and longevity. Exercise therapy has been shown to improve mitochondrial function in patients with mitochondrial disease. However, no information exists about the level of habitual physical activity of people with mitochondrial disease and its relationship with clinical phenotype.Habitual physical activity, genotype and clinical presentations were assessed in 100 patients with mitochondrial disease. Comparisons were made with a control group individually matched by age, gender and BMI. = −0.49; 95% CI −0.33, −0.63, P<0.01). There were no systematic differences in physical activity between different genotypes mitochondrial disease.These results demonstrate for the first time that low levels of physical activity are prominent in mitochondrial disease. Combined with a high prevalence of obesity, physical activity may constitute a significant and potentially modifiable risk factor in mitochondrial disease

    Extreme behavioural shifts by baboons exploiting risky, resource-rich, human-modified environments

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    Abstract A range of species exploit anthropogenic food resources in behaviour known as ‘raiding’. Such behavioural flexibility is considered a central component of a species’ ability to cope with human-induced environmental changes. Here, we study the behavioural processes by which raiding male chacma baboons (Papio ursinus) exploit the opportunities and mitigate the risks presented by raiding in the suburbs of Cape Town, South Africa. Ecological sampling and interviews conducted with ‘rangers’ (employed to manage the baboons’ space use) revealed that baboons are at risk of being herded out of urban spaces that contain high-energy anthropogenic food sources. Baboon-attached motion/GPS tracking collars showed that raiding male baboons spent almost all of their time at the urban edge, engaging in short, high-activity forays into the urban space. Moreover, activity levels were increased where the likelihood of deterrence by rangers was greater. Overall, these raiding baboons display a time-activity balance that is drastically altered in comparison to individuals living in more remote regions. We suggest our methods can be used to obtain precise estimates of management impact for this and other species in conflict with people

    Improvement of the Trivalent Inactivated Flu Vaccine Using PapMV Nanoparticles

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    Commercial seasonal flu vaccines induce production of antibodies directed mostly towards hemaglutinin (HA). Because HA changes rapidly in the circulating virus, the protection remains partial. Several conserved viral proteins, e.g., nucleocapsid (NP) and matrix proteins (M1), are present in the vaccine, but are not immunogenic. To improve the protection provided by these vaccines, we used nanoparticles made of the coat protein of a plant virus (papaya mosaic virus; PapMV) as an adjuvant. Immunization of mice and ferrets with the adjuvanted formulation increased the magnitude and breadth of the humoral response to NP and to highly conserved regions of HA. They also triggered a cellular mediated immune response to NP and M1, and long-lasting protection in animals challenged with a heterosubtypic influenza strain (WSN/33). Thus, seasonal flu vaccine adjuvanted with PapMV nanoparticles can induce universal protection to influenza, which is a major advancement when facing a pandemic
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