301 research outputs found

    Male age mediates reproductive investment and response to paternity assurance.

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    addresses: Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, , Cornwall Campus, Penryn TR10 9EZ, UK, Department of Genetics, University of Georgia, , Athens, GA 30602, USA.types: Journal ArticleTheory predicts that male response to reduced paternity will depend on male state and interactions between the sexes. If there is little chance of reproducing again, then males should invest heavily in current offspring, regardless of their share in paternity. We tested this by manipulating male age and paternity assurance in the burying beetle Nicrophorus vespilloides. We found older males invested more in both mating effort and parental effort than younger males. Furthermore, male age, a component of male state, mediated male response to perceived paternity. Older males provided more prenatal care, whereas younger males provided less prenatal care, when perceived paternity was low. Adjustments in male care, however, did not influence selection acting indirectly on parents, through offspring performance. This is because females adjusted their care in response to the age of their partner, providing less care when paired with older males than younger males. As a result offspring, performance did not differ between treatments. Our study shows, for the first time, that a male state variable is an important modifier of paternity-parental care trade-offs and highlights the importance of social interactions between males and females during care in determining male response to perceived paternity

    Formation of unique nanocrystalline Cu-In-Se bulk pn homojunctions for opto-electronic devices

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    Semiconductor pn junctions, integrated in optoelectronic devices require high quality crystals, made by expensive, technically difficult processes. Bulk heterojunction (BHJ) structures offer practical alternatives to circumvent the cost, flexibility and scale-up challenges of crystalline planar pn junctions. Fabrication methods for the current organic or inorganic BHJ structures invariably create interface mismatch and low doping issues. To overcome such issues, we devised an innovative approach, founded on novel inorganic material system that ensued from single-step electrodeposited copper-indium-selenide compounds. Surface analytical microscopies and spectroscopies reveal unusual phenomena, electro-optical properties and quantum effects. They support the formation of highly-ordered, sharp, abrupt 3-dimensional nanoscale pn BHJs that facilitate efficient charge carrier separation and transport, and essentially perform the same functions as crystalline planar pn junctions. This approach offers a low-cost processing platform to create nanocrystalline films, with the attributes necessary for efficient BHJ operation. It allows roll-to-roll processing of flexible devices in simple thin-film form factor.Partial funding for this work is provided by customers of Xcel Energy through a grant from the Renewable Development Fund. The authors gratefully acknowledge sample preparation, analytical contributions and useful discussions with Sharmila Menezes and Yan Li (InterPhases Solar); Senli Guo (Brucker Nano); Terrence McGuckin (Ephemeron Labs); and Nassim Rahimi (HORIBA Scientific). A. Samantilleke acknowledges Prof. L. M. Peter (Bath University, UK) for introducing EER technique

    Scientific Opinion on the evaluation of the safety in use of Yohimbe (Pausinystalia yohimbe (K. Schum.) Pierre ex Beille)

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    The Panel on Food Additives and Nutrient Sources added to Food provides a scientific opinion evaluating the safety in use of yohimbe bark and its preparations originating from Yohimbe (Pausinystalia yohimbe (K. Schum.) Pierre ex Beille when used in food, e.g. in food supplements. The bark of the plant contains a number of indole alkaloids of biological relevance and preparations of yohimbe bark have been traditionally used as general tonic, performance enhancer and as an aphrodisiac. Food supplements containing yohimbe bark preparations are available nowadays, especially via internet retail. Yohimbine, the major alkaloid of yohimbe bark and raubasine, another alkaloid occurring in lower concentrations in the bark, are used as active ingredients in a number of medicinal products for which adverse effects are described. The Panel reviewed the available scientific data on a possible association between the intake of yohimbe bark and its preparations and potential harmful effects on health. When those data were not available, priority was given to yohimbine, as the only alkaloid for which occurrence had been shown and quantified in food supplements containing yohimbe bark. The Panel concluded that the chemical and toxicological characterisation of yohimbe bark and its preparations for use in food are not adequate to conclude on their safety as ingredients of food, e.g. in food supplements. Thus the Panel could not provide advice on a daily intake of yohimbe bark and its preparations that do not give rise to concerns about harmful effects to health. An estimation of exposure to yohimbine from food supplements was performed showing that theoretical maximum daily intake may exceed the maximum approved daily dose of yohimbine from use as a medicinal product

    Effect of discriminative plant-sugar feeding on the survival and fecundity of Anopheles gambiae

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    <p>Abstract</p> <p>Background</p> <p>A previous study showed for <it>Anopheles gambiae s.s</it>. a gradation of feeding preference on common plant species growing in a malaria holoendemic area in western Kenya. The present follow-up study determines whether there is a relationship between the mosquito's preferences and its survival and fecundity.</p> <p>Methods</p> <p>Groups of mosquitoes were separately given <it>ad libitum </it>opportunity to feed on five of the more preferred plant species (<it>Hamelia patens</it>, <it>Parthenium hysterophorus</it>, <it>Ricinus communis</it>, <it>Senna didymobotrya</it>, and <it>Tecoma stans</it>) and one of the less preferred species (<it>Lantana camara</it>). The mosquitoes were monitored daily for survival. Sugar solution (glucose 6%) and water were used as controls. In addition, the fecundity of mosquitoes on each plant after (i) only one blood meal (number of eggs oviposited), and (ii) after three consecutive blood meals (proportion of females ovipositing, number of eggs oviposited and hatchability of eggs), was determined. The composition and concentration of sugar in the fed-on parts of each plant species were determined using gas chromatography. Using SAS statistical package, tests for significant difference of the fitness values between mosquitoes exposed to different plant species were conducted.</p> <p>Results and Conclusion</p> <p><it>Anopheles gambiae </it>that had fed on four of the five more preferred plant species (<it>T. stans</it>, <it>S. didymobotrya</it>, <it>R. communis </it>and <it>H. patens</it>, but not <it>P. hysterophorus</it>) lived longer and laid more eggs after one blood meal, when compared with <it>An. gambiae </it>that had fed on the least preferred plant species <it>L. camara</it>. When given three consecutive blood-meals, the percentage of females that oviposited, but not the number of eggs laid, was significantly higher for mosquitoes that had previously fed on the four more preferred plant species. Total sugar concentration in the preferred plant parts was significantly correlated with survival and with the proportion of females that laid eggs. This effect was associated mainly with three sugar types, namely glucose, fructose, and gulose. Except for <it>P. hysterophorus</it>, the results suggest that feeding by mosquitoes on preferred plant species under natural conditions results in higher fitness-related benefits, and that the sugar content in preferred plant parts is largely responsible for these effects.</p

    Emergence of a Novel Avian Pox Disease in British Tit Species

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    Avian pox is a viral disease with a wide host range. In Great Britain, avian pox in birds of the Paridae family was first diagnosed in a great tit (Parus major) from south-east England in 2006. An increasing number of avian pox incidents in Paridae have been reported each year since, indicative of an emergent infection. Here, we utilise a database of opportunistic reports of garden bird mortality and morbidity to analyse spatial and temporal patterns of suspected avian pox throughout Great Britain, 2006–2010. Reports of affected Paridae (211 incidents) outnumbered reports in non-Paridae (91 incidents). The majority (90%) of Paridae incidents involved great tits. Paridae pox incidents were more likely to involve multiple individuals (77.3%) than were incidents in non-Paridae hosts (31.9%). Unlike the small wart-like lesions usually seen in non-Paridae with avian pox in Great Britain, lesions in Paridae were frequently large, often with an ulcerated surface and caseous core. Spatial analyses revealed strong clustering of suspected avian pox incidents involving Paridae hosts, but only weak, inconsistent clustering of incidents involving non-Paridae hosts. There was no spatial association between Paridae and non-Paridae incidents. We documented significant spatial spread of Paridae pox from an origin in south-east England; no spatial spread was evident for non-Paridae pox. For both host clades, there was an annual peak of reports in August/September. Sequencing of the avian poxvirus 4b core protein produced an identical viral sequence from each of 20 great tits tested from Great Britain. This sequence was identical to that from great tits from central Europe and Scandinavia. In contrast, sequence variation was evident amongst virus tested from 17 non-Paridae hosts of 5 species. Our findings show Paridae pox to be an emerging infectious disease in wild birds in Great Britain, apparently originating from viral incursion from central Europe or Scandinavia

    Healthcare-associated viral and bacterial infections in dentistry

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    Infection prevention in dentistry is an important topic that has gained more interest in recent years and guidelines for the prevention of cross-transmission are common practice in many countries. However, little is known about the real risks of cross-transmission, specifically in the dental healthcare setting. This paper evaluated the literature to determine the risk of cross-transmission and infection of viruses and bacteria that are of particular relevance in the dental practice environment. Facts from the literature on HSV, VZV, HIV, Hepatitis B, C and D viruses, Mycobacterium spp., Pseudomonas spp., Legionella spp. and multi-resistant bacteria are presented. There is evidence that Hepatitis B virus is a real threat for cross-infection in dentistry. Data for the transmission of, and infection with, other viruses or bacteria in dental practice are scarce. However, a number of cases are probably not acknowledged by patients, healthcare workers and authorities. Furthermore, cross-transmission in dentistry is under-reported in the literature. For the above reasons, the real risks of cross-transmission are likely to be higher. There is therefore a need for prospective longitudinal research in this area, to determine the real risks of cross-infection in dentistry. This will assist the adoption of effective hygiene procedures in dental practice
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