248 research outputs found

    The Precursors and Products of Justice Climates: Group Leader Antecedents and Employee Attitudinal Consequences

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    Drawing on the organizational justice, organizational climate, leadership and personality, and social comparison theory literatures, we develop hypotheses about the effects of leader personality on the development of three types of justice climates (e.g., procedural, interpersonal, and informational), and the moderating effects of these climates on individual level justice- attitude relationships. Largely consistent with the theoretically-derived hypotheses, the results showed that leader (a) agreeableness was positively related to procedural, interpersonal and informational justice climates, (b) conscientiousness was positively related to a procedural justice climate, and (c) neuroticism was negatively related to all three types of justice climates. Further, consistent with social comparison theory, multilevel data analyses revealed that the relationship between individual justice perceptions and job attitudes (e.g., job satisfaction, commitment) was moderated by justice climate such that the relationships were stronger when justice climate was high

    Assessing potential sources of clustering in individually randomised trials

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    Recent reviews have shown that while clustering is extremely common in individually randomised trials (for example, clustering within centre, therapist, or surgeon), it is rarely accounted for in the trial analysis. Our aim is to develop a general framework for assessing whether potential sources of clustering must be accounted for in the trial analysis to obtain valid type I error rates (non-ignorable clustering), with a particular focus on individually randomised trials

    Nutritional correlates of koala persistence in a low-density population

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    It is widely postulated that nutritional factors drive bottom-up, resource-based patterns in herbivore ecology and distribution. There is, however, much controversy over the roles of different plant constituents and how these influence individual herbivores and herbivore populations. The density of koala (Phascolarctos cinereus) populations varies widely and many attribute population trends to variation in the nutritional quality of the eucalypt leaves of their diet, but there is little evidence to support this hypothesis. We used a nested design that involved sampling of trees at two spatial scales to investigate how leaf chemistry influences free-living koalas from a low-density population in south east New South Wales, Australia. Using koala faecal pellets as a proxy for koala visitation to trees, we found an interaction between toxins and nutrients in leaves at a small spatial scale, whereby koalas preferred trees with leaves of higher concentrations of available nitrogen but lower concentrations of sideroxylonals (secondary metabolites found exclusively in eucalypts) compared to neighbouring trees of the same species. We argue that taxonomic and phenotypic diversity is likely to be important when foraging in habitats of low nutritional quality in providing diet choice to tradeoff nutrients and toxins and minimise movement costs. Our findings suggest that immediate nutritional concerns are an important priority of folivores in low-quality habitats and imply that nutritional limitations play an important role in constraining folivore populations. We show that, with a careful experimental design, it is possible to make inferences about populations of herbivores that exist at extremely low densities and thus achieve a better understanding about how plant composition influences herbivore ecology and persistence.IW and WF received a grant from New South Wales (NSW) Department of Environment, Climate Change & Water

    Linkage Group Selection: Towards Identifying Genes Controlling Strain Specific Protective Immunity in Malaria

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    Protective immunity against blood infections of malaria is partly specific to the genotype, or strain, of the parasites. The target antigens of Strain Specific Protective Immunity are expected, therefore, to be antigenically and genetically distinct in different lines of parasite. Here we describe the use of a genetic approach, Linkage Group Selection, to locate the target(s) of Strain Specific Protective Immunity in the rodent malaria parasite Plasmodium chabaudi chabaudi. In a previous such analysis using the progeny of a genetic cross between P. c. chabaudi lines AS-pyr1 and CB, a location on P. c. chabaudi chromosome 8 containing the gene for merozoite surface protein-1, a known candidate antigen for Strain Specific Protective Immunity, was strongly selected. P. c. chabaudi apical membrane antigen-1, another candidate for Strain Specific Protective Immunity, could not have been evaluated in this cross as AS-pyr1 and CB are identical within the cell surface domain of this protein. Here we use Linkage Group Selection analysis of Strain Specific Protective Immunity in a cross between P. c. chabaudi lines CB-pyr10 and AJ, in which merozoite surface protein-1 and apical membrane antigen-1 are both genetically distinct. In this analysis strain specific immune selection acted strongly on the region of P. c. chabaudi chromosome 8 encoding merozoite surface protein-1 and, less strongly, on the P. c. chabaudi chromosome 9 region encoding apical membrane antigen-1. The evidence from these two independent studies indicates that Strain Specific Protective Immunity in P. c. chabaudi in mice is mainly determined by a narrow region of the P. c. chabaudi genome containing the gene for the P. c. chabaudi merozoite surface protein-1 protein. Other regions, including that containing the gene for P. c. chabaudi apical membrane antigen-1, may be more weakly associated with Strain Specific Protective Immunity in these parasites

    Chronic non-specific low back pain - sub-groups or a single mechanism?

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    Copyright 2008 Wand and O'Connell; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Low back pain is a substantial health problem and has subsequently attracted a considerable amount of research. Clinical trials evaluating the efficacy of a variety of interventions for chronic non-specific low back pain indicate limited effectiveness for most commonly applied interventions and approaches. Discussion: Many clinicians challenge the results of clinical trials as they feel that this lack of effectiveness is at odds with their clinical experience of managing patients with back pain. A common explanation for this discrepancy is the perceived heterogeneity of patients with chronic non-specific low back pain. It is felt that the effects of treatment may be diluted by the application of a single intervention to a complex, heterogeneous group with diverse treatment needs. This argument presupposes that current treatment is effective when applied to the correct patient. An alternative perspective is that the clinical trials are correct and current treatments have limited efficacy. Preoccupation with sub-grouping may stifle engagement with this view and it is important that the sub-grouping paradigm is closely examined. This paper argues that there are numerous problems with the sub-grouping approach and that it may not be an important reason for the disappointing results of clinical trials. We propose instead that current treatment may be ineffective because it has been misdirected. Recent evidence that demonstrates changes within the brain in chronic low back pain sufferers raises the possibility that persistent back pain may be a problem of cortical reorganisation and degeneration. This perspective offers interesting insights into the chronic low back pain experience and suggests alternative models of intervention. Summary: The disappointing results of clinical research are commonly explained by the failure of researchers to adequately attend to sub-grouping of the chronic non-specific low back pain population. Alternatively, current approaches may be ineffective and clinicians and researchers may need to radically rethink the nature of the problem and how it should best be managed

    Community-associated Methicillin-resistant Staphylococcus aureus Bacteremia and Endocarditis among HIV Patients: A cohort study

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    <p>Abstract</p> <p>Background</p> <p>HIV patients are at increased risk of development of infections and infection-associated poor health outcomes. We aimed to 1) assess the prevalence of USA300 community-associated methicillin-resistant <it>Staphylococcus aureus </it>(CA-MRSA) among HIV-infected patients with <it>S. aureus </it>bloodstream infections and. 2) determine risk factors for infective endocarditis and in-hospital mortality among patients in this population.</p> <p>Methods</p> <p>All adult HIV-infected patients with documented <it>S. aureus </it>bacteremia admitted to the University of Maryland Medical Center between January 1, 2003 and December 31, 2005 were included. CA-MRSA was defined as a USA300 MRSA isolate with the MBQBLO spa-type motif and positive for both the arginine catabolic mobile element and Panton-Valentin Leukocidin. Risk factors for <it>S. aureus</it>-associated infective endocarditis and mortality were determined using logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI). Potential risk factors included demographic variables, comorbid illnesses, and intravenous drug use.</p> <p>Results</p> <p>Among 131 episodes of <it>S. aureus </it>bacteremia, 85 (66%) were MRSA of which 47 (54%) were CA-MRSA. Sixty-three patients (48%) developed endocarditis and 10 patients (8%) died in the hospital on the index admission Patients with CA-MRSA were significantly more likely to develop endocarditis (OR = 2.73, 95% CI = 1.30, 5.71). No other variables including comorbid conditions, current receipt of antiretroviral therapy, pre-culture severity of illness, or CD4 count were significantly associated with endocarditis and none were associated with in-hospital mortality.</p> <p>Conclusions</p> <p>CA-MRSA was significantly associated with an increased incidence of endocarditis in this cohort of HIV patients with MRSA bacteremia. In populations such as these, in which the prevalence of intravenous drug use and probability of endocarditis are both high, efforts must be made for early detection, which may improve treatment outcomes.</p

    The Prevalence of the Term Subluxation in Chiropractic Degree Program Curricula Throughout the World

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    Background: The subluxation construct generates debate within and outside the profession. The International Chiropractic Education Collaboration, comprised of 10 chiropractic programs outside of North America, stated they will only teach subluxation in a historical context. This research sought to determine how many chiropractic institutions worldwide still use the term in their curricula and to expand upon the previous work of Mirtz & and Perle. Methods: Forty-six chiropractic programs, 18 United States (US) and 28 non-US, were identified from the World Federation of Chiropractic Educational Institutions list. Websites were searched by multiple researchers for curricular information September 2016–September 2017. Some data were not available on line, so email requests were made for additional information. Two institutions provided additional information. The total number of mentions of subluxation in course titles, technique course (Tech) descriptions, principles and practice (PP) descriptions, and other course descriptions were reported separately for US and non-US institutions. Means for each category were calculated. The number of course titles and descriptions using subluxation was divided by the total number of courses for each institution and reported as percentages. Results: Means for use of subluxation by US institutions were: Total course titles = .44; Tech = 3.83; PP = 1.50; other = 1.16. For non-US institutions, means were: Total course titles = .07; Tech = .27; PP = .44; other = 0. The mean total number of mentions was 6.94 in US vs. 0.83 in non-US institutions. Similarly, the mean course descriptions was 6.50 in US vs. 0.72 in non-US institutions. Conclusions: The term subluxation was found in all but two US course catalogues. The use of subluxation in US courses rose from a mean of 5.53 in 2011 to 6.50 in 2017. US institutions use the term significantly more frequently than non-US. Possible reasons for this were discussed. Unscientific terms and concepts should have no place in modern education, except perhaps in historical context. Unless these outdated concepts are rejected, the chiropractic profession and individual chiropractors will likely continue to face difficulties integrating with established health care systems and attaining cultural authority as experts in conservative neuro-musculoskeletal health care.https://doi.org/10.1186/s12998-018-0191-

    Metabolic Factors Limiting Performance in Marathon Runners

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    Each year in the past three decades has seen hundreds of thousands of runners register to run a major marathon. Of those who attempt to race over the marathon distance of 26 miles and 385 yards (42.195 kilometers), more than two-fifths experience severe and performance-limiting depletion of physiologic carbohydrate reserves (a phenomenon known as ‘hitting the wall’), and thousands drop out before reaching the finish lines (approximately 1–2% of those who start). Analyses of endurance physiology have often either used coarse approximations to suggest that human glycogen reserves are insufficient to fuel a marathon (making ‘hitting the wall’ seem inevitable), or implied that maximal glycogen loading is required in order to complete a marathon without ‘hitting the wall.’ The present computational study demonstrates that the energetic constraints on endurance runners are more subtle, and depend on several physiologic variables including the muscle mass distribution, liver and muscle glycogen densities, and running speed (exercise intensity as a fraction of aerobic capacity) of individual runners, in personalized but nevertheless quantifiable and predictable ways. The analytic approach presented here is used to estimate the distance at which runners will exhaust their glycogen stores as a function of running intensity. In so doing it also provides a basis for guidelines ensuring the safety and optimizing the performance of endurance runners, both by setting personally appropriate paces and by prescribing midrace fueling requirements for avoiding ‘the wall.’ The present analysis also sheds physiologically principled light on important standards in marathon running that until now have remained empirically defined: The qualifying times for the Boston Marathon

    Impact of Orthologous Gene Replacement on the Circuitry Governing Pilus Gene Transcription in Streptococci

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    The evolutionary history of several genes of the bacterial pathogen Streptococcus pyogenes strongly suggests an origin in another species, acquired via replacement of the counterpart gene (ortholog) following a recombination event. An example of orthologous gene replacement is provided by the nra/rofA locus, which encodes a key regulator of pilus gene transcription. Of biological importance is the previous finding that the presence of the nra- and rofA-lineage alleles, which are approximately 35% divergent, correlates strongly with genetic markers for streptococcal infection at different tissue sites in the human host (skin, throat).In this report, the impact of orthologous gene replacement targeting the nra/rofA locus is experimentally addressed. Replacement of the native nra-lineage allele with a rofA-lineage allele, plus their respective upstream regions, preserved the polarity of Nra effects on pilus gene transcription (i.e., activation) in the skin strain Alab49. Increased pilus gene transcription in the rofA chimera correlated with a higher rate of bacterial growth at the skin. The transcriptional regulator MsmR, which represses nra and pilus gene transcription in the Alab49 parent strain, has a slight activating effect on pilus gene expression in the rofA chimera construct.Data show that exchange of orthologous forms of a regulatory gene is stable and robust, and pathogenicity is preserved. Yet, new phenotypes may also be introduced by altering the circuitry within a complex transcriptional regulatory network. It is proposed that orthologous gene replacement via interspecies exchange is an important mechanism in the evolution of highly recombining bacteria such as S. pyogenes

    Health behaviors and risk factors in those who use complementary and alternative medicine

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    <p>Abstract</p> <p>Background</p> <p>Surveys have generally found that individuals more likely to use complementary and alternative medicine are female, live in the western United States, are likely to have a health complaint, and have a higher socioeconomic status than do nonusers. What is not known is the extent to which those who use complementary and alternative medicine also engage in positive health behaviors, such as smoking cessation or increased physical activity and/or exhibit fewer health risk factors such as obesity. This has been identified as a key research question in a recent Institute of Medicine report. In the present study we sought to determine whether the use of complementary and alternative medicine is associated with health behaviors or risk factors known to impact on health status.</p> <p>Methods</p> <p>The current study is a cross-sectional regression analysis using data from the 2002 National Health Interview Survey. Data were collected in-person from 31,044 adults throughout the 50 states and the District of Columbia.</p> <p>Results</p> <p>After controlling for a range of other factors, we found that engaging in leisure-time physical activity, having consumed alcohol in one's life but not being a current heavy drinker, and being a former smoker are independently associated with the use of CAM. Obese individuals are slightly less likely to use CAM than individuals with a healthy body-mass index. No significant associations were observed between receipt of an influenza vaccine and CAM use.</p> <p>Conclusion</p> <p>Those engaging in positive health behaviors and exhibiting fewer health risk factors are more likely to use CAM than those who forgo positive health behaviors or exhibit more health risk factors. The fact that users of CAM tend to pursue generally healthy lifestyles suggests that they may be open to additional recommendations toward optimizing their health.</p
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