2,021 research outputs found

    In Situ Measurement of the Aerosol Size Distribution in Stratospheric Solid Rocket Motor Exhaust Plumes

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    The concentration and size distribution of aerosol in the stratospheric exhaust plumes of two Space Shuttle rockets and one Titan IV rocket were measured using a two component aerosol sampling system carried aboard a WB‐57F aircraft. Aerosol size distribution in the 0.01 ”m to 4 ”m diameter size range was measured using a two component sampling system. The measured distributions display a trimodal form with modes near 0.005 ”m, 0.09 ”m, and 2.03 ”m and are used to infer the relative mass fractionation among the three modes. While the smallest mode has been estimated to contain as much as 10% of the total mass of SRM exhaust alumina, we find show that the smallest mode contains less than 0.05% of the alumina mass. This fraction is so small so as to significantly reduce the likelihood that heterogeneous reactions on the SRM alumina surfaces could produce a significant global impact on stratospheric chemistry

    Disease associated polymorphisms within the conserved ECR1 enhancer differentially regulate the tissue specific activity of the cannabinoid‐1 receptor gene promoter; implications for cannabinoid pharmacogenetics

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    EH was funded by Medical Research Scotland (PhD-719-2013) and GW Pharmaceuticals. AMcE was funded by BBSRC project grant (BB/N017544/1). PB and DW are funded by the Scottish Government Rural and Environment Science and Analytical Services Division to the Rowett Institute. The authors declare no conflicts of interest.Peer reviewedPublisher PD

    Genome Sequence of Geobacillus stearothermophilus DSM 458, an Antimicrobial-Producing Thermophilic Bacterium, Isolated from a Sugar Beet Factory

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    peer-reviewedThis paper reports the full genome sequence of the antimicrobial-producing bacterium Geobacillus stearothermophilus DSM 458, isolated in a sugar beet factory in Austria. In silico analysis reveals the presence of a number of novel bacteriocin biosynthetic genes

    Robustness analysis of culturing perturbations on Escherichia coli colony biofilm beta-lactam and aminoglycoside antibiotic tolerance

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    <p>Abstract</p> <p>Background</p> <p>Biofilms are ubiquitous. For instance, the majority of medical infections are thought to involve biofilms. However even after decades of investigation, the <it>in vivo </it>efficacy of many antimicrobial strategies is still debated suggesting there is a need for better understanding of biofilm antimicrobial tolerances. The current study's goal is to characterize the robustness of biofilm antibiotic tolerance to medically and industrially relevant culturing perturbations. By definition, robust systems will return similar, predictable responses when perturbed while non-robust systems will return very different and potentially unpredictable responses. The predictability of an antibiotic tolerance response is essential to developing, testing, and employing antimicrobial strategies.</p> <p>Results</p> <p>The antibiotic tolerance of <it>Escherichia coli </it>colony biofilms was tested against beta-lactam and aminoglycoside class antibiotics. Control scenario tolerances were compared to tolerances under culturing perturbations including 1) different nutritional environments 2) different temperatures 3) interruption of cellular quorum sensing and 4) different biofilm culture ages. Here, antibiotic tolerance was defined in terms of culturable biofilm cells recovered after a twenty four hour antibiotic treatment.</p> <p>Colony biofilm antibiotic tolerances were not robust to perturbations. Altering basic culturing parameters like nutritional environment or temperature resulted in very different, non-intuitive antibiotic tolerance responses. Some minor perturbations like increasing the glucose concentration from 0.1 to 1 g/L caused a ten million fold difference in culturable cells over a twenty four hour antibiotic treatment.</p> <p>Conclusions</p> <p>The current study presents a basis for robustness analysis of biofilm antibiotic tolerance. Biofilm antibiotic tolerance can vary in unpredictable manners based on modest changes in culturing conditions. Common antimicrobial testing methods, which only consider a single culturing condition, are not desirable since slight culturing variations can lead to very different outcomes. The presented data suggest it is essential to test antimicrobial strategies over a range of culturing perturbations relevant to the targeted application. In addition, the highly dynamic antibiotic tolerance responses observed here may explain why some current antimicrobial strategies occasionally fail.</p

    Throwing more light on the dark side of psychopathy: An extension of previous findings for the revised Reinforcement Sensitivity Theory

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    a b s t r a c t Despite previous studies of psychopathy and the motivational systems of the Reinforcement Sensitivity Theory (RST) of personality, few have examined psychopathy in light of the revised RST model. In a large sample (N = 779) of young adults, we expand on Hughes, Moore, Morris, and Corr&apos;s (2012) preliminary findings relating primary/secondary psychopathy to revised RST&apos;s three systems: Flight-Flight-Freeze System (FFFS), Behavioral Inhibition System (BIS), and Behavioral Approach System (BAS). Converging results between Hughes et al. and the current study emphasize three major findings: (1) primary psychopathy is negatively related to the BIS as well as the FFFS; (2) primary psychopathy is positively related to goal-driven behavior of the BAS; and, (3) secondary psychopathy is positively related to impulsivity reflected in the BAS. The FFFS was incrementally predictive of primary but not secondary psychopathy. No evidence for a BAS Â BIS interaction in psychopathy was found. Results are discussed in terms of future research directions

    Larger colony sizes favoured the evolution of more worker castes in ants

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    The size–complexity hypothesis is a leading explanation for the evolution of complex life on earth. It predicts that in lineages that have undergone a major transition in organismality, larger numbers of lower-level subunits select for increased division of labour. Current data from multicellular organisms and social insects support a positive correlation between the number of cells and number of cell types and between colony size and the number of castes. However, the implication of these results is unclear, because colony size and number of cells are correlated with other variables which may also influence selection for division of labour, and causality could be in either direction. Here, to resolve this problem, we tested multiple causal hypotheses using data from 794 ant species. We found that larger colony sizes favoured the evolution of increased division of labour, resulting in more worker castes and greater variation in worker size. By contrast, our results did not provide consistent support for alternative hypotheses regarding either queen mating frequency or number of queens per colony explaining variation in division of labour. Overall, our results provide strong support for the size–complexity hypothesis
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