2,343 research outputs found

    Propagation of Transient Perturbations into a Planet's Exosphere: Molecular Kinetic Simulations

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    The upper atmospheres of Mars and Titan, as well as those on many other planetary bodies, exhibit significant density variations vs. altitude that are interpreted as gravity waves. Such data is then used to extract vertical temperature profiles, even when such perturbations propagate through the transition region from a collision dominated regime and into a planet's exosphere. Since the temperature profile is critical for describing the upper atmospheric heating and evolution, we use molecular kinetic simulations to describe transient perturbations in a Mars-like upper atmosphere. We show that the standard methods for extracting the temperature profile can fail dramatically so that molecular kinetic simulations, calibrated to observed density profiles, are needed in this region of a planet's atmosphere

    Lakes in a new light: Indirect effects of ultraviolet radiation

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    Stratospheric ozone concentrations are not expected to recover to pre-ozone hole levels until the mid-21st century and, even after ozone recovery, climate and other anthropogenic changes will continue to alter ultraviolet radiation (UV) exposure regimes in aquatic ecosystems.  Although our understanding of the ecology of UV continues to move towards a new paradigm that emphasises complex interactive and indirect effects of UV on communities of organisms, rather than simple direct negative effects on individuals, considerable uncertainty remains regarding the impacts of sustained or changing UV stress on aquatic ecosystems. In this synthesis we examine the importance of indirect UV effects for some key ecosystem level characteristics and processes in lakes.  We draw particular attention to the implications of UV for disease dynamics, contaminant toxicity, biodiversity, and carbon cycling in lakes. Although UV has strong lethal mutagenic and chronic physiological effects on organisms, we suggest that indirect effect pathways, including UV effects on animal behaviour, food quality, and trophic interactions are likely to be important in lake ecosystem dynamics

    Changing an Unfavorable Employer Reputation: The Roles of Recruitment Message-Type and Familiarity with Employer

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    An unfavorable employer reputation can impair an organization’s ability to recruit job seekers. The present research employed a four-week longitudinal experimental design to investigate whether recruitment messages can positively change an existing unfavorable employer reputation. Two hundred and twenty-two (222) job seekers rated their perceptions of an organization before and after being randomly assigned to receive a series of high- or low-information recruitment messages. As expected, job seekers receiving high-information messages changed their perceptions more than job seekers who were exposed to low-information messages. In addition, job seekers’ initial familiarity with the employer was negatively related to change in their perceptions of employer reputation. Finally, there was some evidence that job seekers’ familiarity with the employer influenced the impact of different recruitment messages. Implications for research and practice are discussed

    Perspectives on safety culture

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    Overviewing selected elements from the literature, this paper locates the notion of safety culture within its parent concept of organisational culture. A distinction is drawn between functionalist and interpretive perspectives on organisational culture. The terms ‘culture’ and ‘climate’ are clarified as they are typically applied to organisations and to safety. A contrast is drawn between strategic top down and data-driven bottom up approaches to human factors as an illustrative aspect of safety. A safety case study is used to illustrate two measurement approaches. Key issues for future study include valid measurement of safety culture and developing methods to adequately represent mechanisms through which safety culture might influence, and be influenced by, other safety factors

    A Bifactor Model of the Polish Version of the Hare Self-Report Psychopathy Scale

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    The 64-item Hare Self-Report Psychopathy Scale was translated into Polish with the aim to test construct validity and dimensionality, incremental validity, and composite reliability of the measure in a sample of working adults (N = 319). Confirmatory factor analyses revealed that the best fitting model was the bifactor conceptualization containing six latent factors; two general factors of psychopathy and four grouping factors represented by interpersonal, affective, antisocial, and lifestyle latent variables (compared to a 2-factor, 4-factor, and 4-factor with 2 hierarchical factors). The scores of the Polish version of Hare SRP evidenced good composite reliability and incremental validity in terms of predicting scores on aggression scale. Implications for theory and future research are discussed

    Identification of dfrA14 in two distinct plasmids conferring trimethoprim resistance in Actinobacillus pleuropneumoniae

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    OBJECTIVES: The objective of this study was to determine the distribution and genetic basis of trimethoprim resistance in Actinobacillus pleuropneumoniae isolates from pigs in England. METHODS: Clinical isolates collected between 1998 and 2011 were tested for resistance to trimethoprim and sulphonamide. The genetic basis of trimethoprim resistance was determined by shotgun WGS analysis and the subsequent isolation and sequencing of plasmids. RESULTS: A total of 16 (out of 106) A. pleuropneumoniae isolates were resistant to both trimethoprim (MIC >32 mg/L) and sulfisoxazole (MIC ≥256 mg/L), and a further 32 were resistant only to sulfisoxazole (MIC ≥256 mg/L). Genome sequence data for the trimethoprim-resistant isolates revealed the presence of the dfrA14 dihydrofolate reductase gene. The distribution of plasmid sequences in multiple contigs suggested the presence of two distinct dfrA14-containing plasmids in different isolates, which was confirmed by plasmid isolation and sequencing. Both plasmids encoded mobilization genes, the sulphonamide resistance gene sul2, as well as dfrA14 inserted into strA, a streptomycin-resistance-associated gene, although the gene order differed between the two plasmids. One of the plasmids further encoded the strB streptomycin-resistance-associated gene. CONCLUSIONS: This is the first description of mobilizable plasmids conferring trimethoprim resistance in A. pleuropneumoniae and, to our knowledge, the first report of dfrA14 in any member of the Pasteurellaceae. The identification of dfrA14 conferring trimethoprim resistance in A. pleuropneumoniae isolates will facilitate PCR screens for resistance to this important antimicrobial

    Increased risk of A(H1N1)pdm09 influenza infection in UK pig industry workers compared to a general population cohort.

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    BACKGROUND: Pigs are mixing vessels for influenza viral reassortment but the extent of influenza transmission between swine and humans is not well understood. OBJECTIVES: To assess whether occupational exposure to pigs is a risk factor for human infection with human and swine-adapted influenza viruses. METHODS: UK pig industry workers were frequency-matched on age, region, sampling month, and gender with a community-based comparison group from the Flu Watch study. HI assays quantified antibodies for swine and human A(H1) and A(H3) influenza viruses (titres≥40 considered seropositive and indicative of infection). Virus-specific associations between seropositivity and occupational pig exposure were examined using multivariable regression models adjusted for vaccination. Pigs on the same farms were also tested for seropositivity. RESULTS: 42% of pigs were seropositive to A(H1N1)pdm09. Pig industry workers showed evidence of increased odds of A(H1N1)pdm09 seropositivity compared to the comparison group, albeit with wide confidence intervals (CI), Adjusted Odds Ratio after accounting for possible cross reactivity with other swine A(H1) viruses (aOR) 25.3, 95% CI [1.4-536.3], p=0.028. CONCLUSION: The results indicate that A(H1N1)pdm09 virus was common in UK pigs during the pandemic and subsequent period of human A(H1N1)pdm09 circulation, and occupational exposure to pigs was a risk factor for human infection. Influenza immunization of pig industry workers may reduce transmission and the potential for virus reassortment. This article is protected by copyright. All rights reserved

    Analysis of human performance as a measure of mental fatigue

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    In our day to day, we often experience a sense of being tired due to mental or physical workload. Along with that, there is also a feeling of degrading performance, even after the completion of simple tasks. These mental states however, are often not felt consciously or are ignored. This is an attitude that may result in human error, failure, and may lead to potential health problems together with a decrease in quality of life. States of acute mental fatigue may be detected with the close monitoring of certain indicators, such as productivity, performance and health indicators. In this paper, a model and prototype are proposed to detect and monitor acute acute fatigue, based on non-invasive Humancomputer Interaction (HCI). This approach will enable the development of better working environments, with an impact on the quality of life and the work produced.This work was developed in the context of the project CAMCoF - Contextaware Multimodal Communication Framework funded by ERDF - European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT - Funda ção para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within project FCOMP-01-0124-FEDER-028980

    1-Aminocyclopropane-1-carboxylic acid (ACC) concentration and ACC synthase expression in soybean roots, root tips, and soybean cyst nematode (Heterodera glycines)-infected roots

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    Colonization of plant roots by root knot and cyst nematodes requires a functional ethylene response pathway. However, ethylene plays many roles in root development and whether its role in nematode colonization is direct or indirect, for example lateral root initiation or root hair growth, is not known. The temporal requirement for ethylene and localized synthesis of ethylene during the life span of soybean cyst nematode (SCN) on soybean roots was further investigated. Although a significant increase in ethylene evolution was not detected from SCN-colonized roots, the concentration of the immediate precursor to ethylene, 1-aminocyclopropane-1-carboxylic acid (ACC), was higher in SCN-colonized root pieces and root tips than in other parts of the root. Moreover, expression analysis of 17 ACC synthase (ACS) genes indicated that a select set of ACS genes is expressed in SCN-colonized root pieces that is clearly different from the set of genes expressed in non-colonized roots or root tips. Semi-quantitative real-time PCR indicated that ACS transcript accumulation correlates with the high concentration of ACC in root tips. In addition, an ACS-like sequence was found in the public SCN nucleotide database. Acquisition of a full-length sequence for this mRNA (accession GQ389647) and alignment with transcripts for other well-characterized ACS proteins indicated that the nematode sequence is missing a key element required for ACS activity and therefore probably is not a functional ACS. Moreover, no significant amount of ACC was found in any growth stage of SCN that was tested

    The Blanco Cosmology Survey: Data Acquisition, Processing, Calibration, Quality Diagnostics and Data Release

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    The Blanco Cosmology Survey (BCS) is a 60 night imaging survey of \sim80 deg2^2 of the southern sky located in two fields: (α\alpha,δ\delta)= (5 hr, 55-55^{\circ}) and (23 hr, 55-55^{\circ}). The survey was carried out between 2005 and 2008 in grizgriz bands with the Mosaic2 imager on the Blanco 4m telescope. The primary aim of the BCS survey is to provide the data required to optically confirm and measure photometric redshifts for Sunyaev-Zel'dovich effect selected galaxy clusters from the South Pole Telescope and the Atacama Cosmology Telescope. We process and calibrate the BCS data, carrying out PSF corrected model fitting photometry for all detected objects. The median 10σ\sigma galaxy (point source) depths over the survey in grizgriz are approximately 23.3 (23.9), 23.4 (24.0), 23.0 (23.6) and 21.3 (22.1), respectively. The astrometric accuracy relative to the USNO-B survey is 45\sim45 milli-arcsec. We calibrate our absolute photometry using the stellar locus in grizJgrizJ bands, and thus our absolute photometric scale derives from 2MASS which has 2\sim2% accuracy. The scatter of stars about the stellar locus indicates a systematics floor in the relative stellar photometric scatter in grizgriz that is \sim1.9%, \sim2.2%, \sim2.7% and\sim2.7%, respectively. A simple cut in the AstrOmatic star-galaxy classifier {\tt spread\_model} produces a star sample with good spatial uniformity. We use the resulting photometric catalogs to calibrate photometric redshifts for the survey and demonstrate scatter δz/(1+z)=0.054\delta z/(1+z)=0.054 with an outlier fraction η<5\eta<5% to z1z\sim1. We highlight some selected science results to date and provide a full description of the released data products.Comment: 23 pages, 23 figures . Response to referee comments. Paper accepted for publication. BCS catalogs and images available for download from http://www.usm.uni-muenchen.de/BC
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