511 research outputs found

    Trajectories of childhood neighbourhood cohesion and adolescent mental health: evidence from a national Canadian cohort.

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    BACKGROUND: The objective of this study was to examine associations between trajectories of childhood neighbourhood social cohesion and adolescent mental health and behaviour. METHOD: This study used data from the National Longitudinal Survey of Children and Youth, a nationally representative sample of Canadian children. The sample included 5577 children aged 0-3 years in 1994-1995, prospectively followed until age 12-15 years. Parental perceived neighbourhood cohesion was assessed every 2 years. Latent growth class modelling was used to identify trajectories of neighbourhood cohesion. Mental health and behavioural outcomes were self-reported at age 12-15 years. Logistic regression was used to examine associations between neighbourhood cohesion trajectories and outcomes, adjusting for potential confounders. RESULTS: Five distinct trajectories were identified: 'stable low' (4.2%); 'moderate increasing' (9.1%); 'stable moderate' (68.5%); 'high falling' (8.9%); and 'stable high' (9.3%). Relative to those living in stable moderately cohesive neighbourhoods, those in stable low cohesive neighbourhoods were more likely to experience symptoms of anxiety/depression [odds ratio (OR) = 1.73, 95% confidence interval (CI) 1.04-2.90] and engage in indirect aggression (OR = 1.62, 95% CI 1.07-2.45). Those with improvements in neighbourhood cohesion had significantly lower odds of hyperactivity (OR = 0.67, 95% CI 0.46-0.98) and indirect aggression (OR = 0.69, 95% CI 0.49-0.96). In contrast, those with a decline in neighbourhood cohesion had increased odds of hyperactivity (OR = 1.67, 95% CI 1.21-2.29). Those in highly cohesive neighbourhoods in early childhood were more likely to engage in prosocial behaviour ('high falling': OR = 1.93, 95% CI 1.38-2.69; 'stable high': OR = 1.89, 95% CI 1.35-2.63). CONCLUSIONS: These results suggest that neighbourhood cohesion in childhood may have time-sensitive effects on several domains of adolescent mental health and behaviour

    Verified and potential pathogens of predatory mites (Acari: Phytoseiidae)

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    Several species of phytoseiid mites (Acari: Phytoseiidae), including species of the genera Amblyseius, Galendromus, Metaseiulus, Neoseiulus, Phytoseiulus and Typhlodromus, are currently reared for biological control of various crop pests and/or as model organisms for the study of predator¿prey interactions. Pathogen-free phytoseiid mites are important to obtain high efficacy in biological pest control and to get reliable data in mite research, as pathogens may affect the performance of their host or alter their reproduction and behaviour. Potential and verified pathogens have been reported for phytoseiid mites during the past 25 years. The present review provides an overview, including potential pathogens with unknown host effects (17 reports), endosymbiotic Wolbachia (seven reports), other bacteria (including Cardinium and Spiroplasma) (four reports), cases of unidentified diseases (three reports) and cases of verified pathogens (six reports). From the latter group four reports refer to Microsporidia, one to a fungus and one to a bacterium. Only five entities have been studied in detail, including Wolbachia infecting seven predatory mite species, other endosymbiotic bacteria infecting Metaseiulus (Galendromus, Typhlodromus) occidentalis (Nesbitt), the bacterium Acaricomes phytoseiuli infecting Phytoseiulus persimilis Athias-Henriot, the microsporidium Microsporidium phytoseiuli infecting P. persimilis and the microsporidium Oligosproridium occidentalis infecting M. occidentalis. In four cases (Wolbachia, A. phytoseiuli, M. phytoseiuli and O. occidentalis) an infection may be connected with fitness costs of the host. Moreover, infection is not always readily visible as no obvious gross symptoms are present. Monitoring of these entities on a routine and continuous basis should therefore get more attention, especially in commercial mass-production. Special attention should be paid to field-collected mites before introduction into the laboratory or mass rearing, and to mites that are exchanged among rearing facilities. However, at present general pathogen monitoring is not yet practical as effects of many entities are unknown. More research effort is needed concerning verified and potential pathogens of commercially reared arthropods and those used as model organisms in research

    The Pioneer Anomaly

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    Radio-metric Doppler tracking data received from the Pioneer 10 and 11 spacecraft from heliocentric distances of 20-70 AU has consistently indicated the presence of a small, anomalous, blue-shifted frequency drift uniformly changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was interpreted as a constant sunward deceleration of each particular spacecraft at the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of the Newton's gravitational inverse-square law has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. In this review, we summarize the current knowledge of the physical properties of the anomaly and the conditions that led to its detection and characterization. We review various mechanisms proposed to explain the anomaly and discuss the current state of efforts to determine its nature. A comprehensive new investigation of the anomalous behavior of the two Pioneers has begun recently. The new efforts rely on the much-extended set of radio-metric Doppler data for both spacecraft in conjunction with the newly available complete record of their telemetry files and a large archive of original project documentation. As the new study is yet to report its findings, this review provides the necessary background for the new results to appear in the near future. In particular, we provide a significant amount of information on the design, operations and behavior of the two Pioneers during their entire missions, including descriptions of various data formats and techniques used for their navigation and radio-science data analysis. As most of this information was recovered relatively recently, it was not used in the previous studies of the Pioneer anomaly, but it is critical for the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living Reviews in Relativit

    Can Systemic Interventions Designed to Reduce Reoffending by Youth also Reduce their Victimization?

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    Previous research indicates considerable overlap between populations of boys who are victimized and boys who victimize others. This study was concerned with whether a systems-focused treatment program designed to address individual and systemic risk factors associated with the perpetration of sexual and violent crimes might also be successful in reducing boys’ victimization by others. Boys adjudicated for sexual offences who received ‘treatment as usual’ (TAU; n = 335) were compared with similarly adjudicated boys who completed the treatment program (n = 200) on their histories of contact with police either as offenders or victims. Despite their higher rates of pre-intervention victimization, the treatment group were victimized less frequently post-intervention than the TAU group. Continued offending was the strongest predictor of victimization post-intervention. These findings suggest that offending and victimization share common risk factors that may be addressed simultaneously within offence-focused treatment

    Quantitative imaging of concentrated suspensions under flow

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    We review recent advances in imaging the flow of concentrated suspensions, focussing on the use of confocal microscopy to obtain time-resolved information on the single-particle level in these systems. After motivating the need for quantitative (confocal) imaging in suspension rheology, we briefly describe the particles, sample environments, microscopy tools and analysis algorithms needed to perform this kind of experiments. The second part of the review focusses on microscopic aspects of the flow of concentrated model hard-sphere-like suspensions, and the relation to non-linear rheological phenomena such as yielding, shear localization, wall slip and shear-induced ordering. Both Brownian and non-Brownian systems will be described. We show how quantitative imaging can improve our understanding of the connection between microscopic dynamics and bulk flow.Comment: Review on imaging hard-sphere suspensions, incl summary of methodology. Submitted for special volume 'High Solid Dispersions' ed. M. Cloitre, Vol. xx of 'Advances and Polymer Science' (Springer, Berlin, 2009); 22 pages, 16 fig

    Mating dynamics in a nematode with three sexes and its evolutionary implications

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    Nematodes have diverse reproductive strategies, which make them ideal subjects for comparative studies to address how mating systems evolve. Here we present the sex ratios and mating dynamics of the free-living nematode Rhabditis sp. SB347, in which males, females and hermaphrodites co-exist. The three sexes are produced by both selfing and outcrossing, and females tend to appear early in a mother’s progeny. Males prefer mating with females over hermaphrodites, which our results suggest is related to the female-specific production of the sex pheromones ascr#1 and ascr#9. We discuss the parallels between this system and that of parasitic nematodes that exhibit alternation between uniparental and biparental reproduction

    Value of hospital antimicrobial stewardship programs [ASPs]:a systematic review

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    Abstract Background Hospital antimicrobial stewardship programs (ASPs) aim to promote judicious use of antimicrobials to combat antimicrobial resistance. For ASPs to be developed, adopted, and implemented, an economic value assessment is essential. Few studies demonstrate the cost-effectiveness of ASPs. This systematic review aimed to evaluate the economic and clinical impact of ASPs. Methods An update to the Dik et al. systematic review (2000–2014) was conducted on EMBASE and Medline using PRISMA guidelines. The updated search was limited to primary research studies in English (30 September 2014–31 December 2017) that evaluated patient and/or economic outcomes after implementation of hospital ASPs including length of stay (LOS), antimicrobial use, and total (including operational and implementation) costs. Results One hundred forty-six studies meeting inclusion criteria were included. The majority of these studies were conducted within the last 5 years in North America (49%), Europe (25%), and Asia (14%), with few studies conducted in Africa (3%), South America (3%), and Australia (3%). Most studies were conducted in hospitals with 500–1000 beds and evaluated LOS and change in antibiotic expenditure, the majority of which showed a decrease in LOS (85%) and antibiotic expenditure (92%). The mean cost-savings varied by hospital size and region after implementation of ASPs. Average cost savings in US studies were 732perpatient(range:732 per patient (range: 2.50 to $2640), with similar trends exhibited in European studies. The key driver of cost savings was from reduction in LOS. Savings were higher among hospitals with comprehensive ASPs which included therapy review and antibiotic restrictions. Conclusions Our data indicates that hospital ASPs have significant value with beneficial clinical and economic impacts. More robust published data is required in terms of implementation, LOS, and overall costs so that decision-makers can make a stronger case for investing in ASPs, considering competing priorities. Such data on ASPs in lower- and middle-income countries is limited and requires urgent attention

    Caracol, Belize, and Changing Perceptions of Ancient Maya Society

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    Conservation genetics of the annual hemiparasitic plant Melampyrum sylvaticum (Orobanchaceae) in the UK and Scandinavia

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    Melampyrum sylvaticum is an endangered annual hemiparasitic plant that is found in only 19 small and isolated populations in the United Kingdom (UK). To evaluate the genetic consequences of this patchy distribution we compared levels of diversity, inbreeding and differentiation from ten populations from the UK with eight relatively large populations from Sweden and Norway where the species is more continuously distributed. We demonstrate that in both the UK and Scandinavia, the species is highly inbreeding (global F IS = 0.899). Levels of population differentiation were high (F’ST = 0.892) and significantly higher amongst UK populations (F’ST = 0.949) than Scandinavian populations (F’ST = 0.762; P < 0.01). The isolated populations in the UK have, on average, lower genetic diversity (allelic richness, proportion of loci that are polymorphic, gene diversity) than Scandinavian populations, and this diversity difference is associated with the smaller census size and population area of UK populations. From a conservation perspective, the naturally inbreeding nature of the species may buffer the species against immediate effects of inbreeding depression, but the markedly lower levels of genetic diversity in UK populations may represent a genetic constraint to evolutionary change. In addition, the high levels of population differentiation suggest that gene flow among populations will not be effective at replenishing lost variation. We thus recommend supporting in situ conservation management with ex situ populations and human-mediated seed dispersal among selected populations in the UK
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