212 research outputs found

    Trophic Dynamics of the Boreal Forests of the Kluane Region

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    The trophic dynamics of the Yukon boreal forest have been under investigation at the Kluane Lake Research Station since 1973. We monitored and conducted experiments on the major species in this ecosystem, except the large mammals (for logistic reasons). The central problem has been to determine the causes of the 9 – 10 year cycle of snowshoe hares, and to achieve this we carried out several large-scale experiments manipulating food supplies, predator pressure, and soil nutrient availability to test hypotheses that food, predation, or habitat quality regulate populations. The hare cycle is driven top-down by predators, and most hares die because they are killed by predators. Predators also cause stress in female hares, and the stress response seems to be responsible for the loss of reproductive potential in the decline and low phases of the hare cycle. Many of the specialist predators and some herbivores in this ecosystem fluctuate with the hare cycle. Arctic ground squirrels do, but red squirrels do not, being linked closely to white spruce seed masting years. Small rodents fluctuate in numbers in two patterns. Red-backed voles and four species of Microtus voles have a 3 – 4 year cycle that seems to be driven by food supplies and social behaviour. Deer mice, in contrast, have fluctuated dramatically in the 38 years we have monitored them, but not cyclically. White spruce seed production varies with temperature and rainfall, but was not affected by adding nutrients in fertilizer. Global warming and reduced hare browsing in the last 20 years have helped to increase the abundance of shrubs in these forests. It will be challenging to predict how this system will change as climatic warming proceeds, because even closely related species in the same trophic level respond differently to perturbations. We recommend continued monitoring of the major species in these boreal forests.La dynamique trophique de la forêt boréale du Yukon fait l’objet d’une étude à la station de recherche du lac Kluane depuis 1973. Nous avons fait des expériences et surveillé les espèces importantes de cet écosystème, sauf en ce qui a trait aux principaux mammifères (pour des raisons de logistique). Le problème central a consisté à déterminer les causes du cycle de 9 à 10 ans du lièvre d’Amérique. Pour ce faire, nous avons effectué plusieurs expériences à grande échelle dans le cadre desquelles nous avons manipulé les disponibilités alimentaires, la pression exercée par les prédateurs et la disponibilité en nutriments dans le sol afin de mettre à l’épreuve les hypothèses selon lesquelles la nourriture, la prédation ou la qualité de l’habitat régularisent les populations. Le cycle du lièvre est dicté par les prédateurs de haut en bas, et la plupart des lièvres meurent parce qu’ils sont tués par les prédateurs. Par ailleurs, les prédateurs sont une source de stress chez les lièvres femelles, et la réaction au stress semble responsable de la perte de capacité de reproduction dans la phase du déclin et la phase basse du cycle du lièvre. Grand nombre des prédateurs spécialistes et certains herbivores de cet écosystème fluctuent en fonction du cycle du lièvre. C’est le cas du spermophile arctique, mais ce n’est pas le cas de l’écureuil roux, car il est étroitement lié aux années de paisson de graines d’épinette blanche. Le nombre de petits rongeurs fluctue en fonction de deux modèles. Le campagnol à dos roux et quatre espèces de campagnols Microtus ont un cycle de trois à quatre ans qui semble dicté par les disponibilités alimentaires et le comportement social, tandis que la souris sylvestre a connu d’énormes fluctuations pendant les 38 années qui ont fait l’objet d’une surveillance, sans toutefois afficher de cycles. La production de graines d’épinette blanche varie en fonction des températures et des chutes de pluie, mais n’a pas été influencée par l’ajout de nutriments au fertilisant. Le réchauffement planétaire et le broutage réduit des lièvres ces 20 dernières années ont aidé à accroître l’abondance d’arbustes dans ces forêts. Il sera difficile de prévoir comment ce système changera au fur et à mesure du réchauffement climatique, car même les espèces étroitement liées du même niveau trophique réagissent aux perturbations de manière différente. Nous recommandons la surveillance continue des principales espèces de ces forêts boréales

    Identifying avian malaria vectors: sampling methods influence outcomes

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    Background The role of vectors in the transmission of avian malaria parasites is currently understudied. Many studies that investigate parasite-vector relationships use limited trapping techniques and/or identify potential competent vectors in the field in such ways that cannot distinguish between an infected or infectious vector. Without the use of multiple trapping techniques that address the specific biology of diverse mosquito species, and without looking at the infection status of individual mosquitoes, it is not possible to make dependable conclusions on the role of mosquitoes in the transmission of avian malaria parasites. Methods We conducted two years of mosquito collections at a riparian preserve in California where a wide diversity of species were collected with multiple trap types. We hypothesized that competent mosquito species can influence the distribution and diversity of avian malaria parasites by acting as a compatibility filter for specific Plasmodium species. To determine the infection status of all individual mosquitoes for Plasmodium species/lineages, amplification within the cytochrome b gene was carried out on over 3000 individual mosquito thoraxes, and for those that tested positive we then repeated the same process for abdomens and salivary glands. Results Our data show heterogeneity in the transmissibility of Plasmodium among ornithophillic mosquito species. More specifically, Culex stigmatosoma appears to not be a vector of Plasmodium homopolare, a parasite that is prevalent in the avian population, but is a vector of multiple other Plasmodium species/lineages. Conclusions Our results suggest that conclusions made on the role of vectors from studies that do not use different mosquito trapping methods should be re-evaluated with caution, as we documented the potential for trapping biases, which may cause studies to miss important roles of specific mosquito species in the transmission of avian malaria. Moreover, we document heterogeneity in the transmission of Plasmodium spp. by mosquitoes can influence Plasmodium diversity and prevalence in specific locations to Plasmodium-vector incompatibilities

    Associations with intraocular pressure across Europe: The European Eye Epidemiology (E3) Consortium

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    Raised intraocular pressure (IOP) is the most important risk factor for developing glaucoma, the second commonest cause of blindness globally. Understanding associations with IOP and variations in IOP between countries may teach us about mechanisms underlying glaucoma. We examined cross-sectional associations with IOP in 43,500 European adults from 12 cohort studies belonging to the European Eye Epidemiology (E3) consortium. Each study conducted multivariable linear regression with IOP as the outcome variable and results were pooled using random effects meta-analysis. The association of standardized study IOP with latitude was tested using meta-regression. Higher IOP was observed in men (0.18 mmHg; 95 % CI 0.06, 0.31; P = 0.004) and with higher body mass index (0.21 mmHg per 5 kg/m2; 95 % CI 0.14, 0.28; P < 0.001), shorter height (−0.17 mmHg per 10 cm; 95 % CI –0.25, −0.08; P < 0.001), higher systolic blood pressure (0.17 mmHg per 10 mmHg; 95 % CI 0.12, 0.22; P < 0.001) and more myopic refraction (0.06 mmHg per Dioptre; 95 % CI 0.03, 0.09; P < 0.001). An inverted U-shaped trend was observed between age and IOP, with IOP increasing up to the age of 60 and decreasing in participants older than 70 years. We found no significant association between standardized IOP and study location latitude (P = 0.76). Novel findings of our study include the association of lower IOP in taller people and an inverted-U shaped association of IOP with age. We found no evidence of significant variation in IOP across Europe. Despite the limited range of latitude amongst included studies, this finding is in favour of collaborative pooling of data from studies examining environmental and genetic determinants of IOP in Europeans

    Bringing emotion to work: Emotional intelligence, resistance, and the reinvention of character

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    This article centrally examines the sociological significance of emotional intelligence (EI) as a nascent managerial discourse. Through developing a three-way reading of the writers Richard Sennett, Daniel Goleman, and George Ritzer, it is contended that EI can be understood to signal ‘new rules’ for work involving demands for workers to develop moral character better attuned to the dynamics of the flexible workplace - character that is more ‘intelligent’, adaptive, and reflexive. Furthermore, it is argued that while EI appears in some important respects to open the scope for worker discretion, it might also signal diminished scope for worker resistance. However, ultimately, the case of EI is used to problematise recent discussions of worker resistance - to suggest the possibility of ‘resistant’ worker agency exercised through collusion with, as well as transgression of, corporate norms and practices

    Gendering the careers of young professionals: some early findings from a longitudinal study. in Organizing/theorizing: developments in organization theory and practice

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    Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales

    Age at first birth in women is genetically associated with increased risk of schizophrenia

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    Prof. Paunio on PGC:n jäsenPrevious studies have shown an increased risk for mental health problems in children born to both younger and older parents compared to children of average-aged parents. We previously used a novel design to reveal a latent mechanism of genetic association between schizophrenia and age at first birth in women (AFB). Here, we use independent data from the UK Biobank (N = 38,892) to replicate the finding of an association between predicted genetic risk of schizophrenia and AFB in women, and to estimate the genetic correlation between schizophrenia and AFB in women stratified into younger and older groups. We find evidence for an association between predicted genetic risk of schizophrenia and AFB in women (P-value = 1.12E-05), and we show genetic heterogeneity between younger and older AFB groups (P-value = 3.45E-03). The genetic correlation between schizophrenia and AFB in the younger AFB group is -0.16 (SE = 0.04) while that between schizophrenia and AFB in the older AFB group is 0.14 (SE = 0.08). Our results suggest that early, and perhaps also late, age at first birth in women is associated with increased genetic risk for schizophrenia in the UK Biobank sample. These findings contribute new insights into factors contributing to the complex bio-social risk architecture underpinning the association between parental age and offspring mental health.Peer reviewe

    Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

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    We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe

    Combination of searches for Higgs boson pairs in pp collisions at \sqrts = 13 TeV with the ATLAS detector

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    This letter presents a combination of searches for Higgs boson pair production using up to 36.1 fb(-1) of proton-proton collision data at a centre-of-mass energy root s = 13 TeV recorded with the ATLAS detector at the LHC. The combination is performed using six analyses searching for Higgs boson pairs decaying into the b (b) over barb (b) over bar, b (b) over barW(+)W(-), b (b) over bar tau(+)tau(-), W+W-W+W-, b (b) over bar gamma gamma and W+W-gamma gamma final states. Results are presented for non-resonant and resonant Higgs boson pair production modes. No statistically significant excess in data above the Standard Model predictions is found. The combined observed (expected) limit at 95% confidence level on the non-resonant Higgs boson pair production cross-section is 6.9 (10) times the predicted Standard Model cross-section. Limits are also set on the ratio (kappa(lambda)) of the Higgs boson self-coupling to its Standard Model value. This ratio is constrained at 95% confidence level in observation (expectation) to -5.0 &lt; kappa(lambda) &lt; 12.0 (-5.8 &lt; kappa(lambda) &lt; 12.0). In addition, limits are set on the production of narrow scalar resonances and spin-2 Kaluza-Klein Randall-Sundrum gravitons. Exclusion regions are also provided in the parameter space of the habemus Minimal Supersymmetric Standard Model and the Electroweak Singlet Model. For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2019.135103</p

    Searches for lepton-flavour-violating decays of the Higgs boson in s=13\sqrt{s}=13 TeV pp\mathit{pp} collisions with the ATLAS detector

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    This Letter presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → μτ , performed with the ATLAS detector at the LHC. The searches are based on a data sample of proton–proton collisions at a centre-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 36.1 fb−1. No significant excess is observed above the expected background from Standard Model processes. The observed (median expected) 95% confidence-level upper limits on the leptonflavour-violating branching ratios are 0.47% (0.34+0.13−0.10%) and 0.28% (0.37+0.14−0.10%) for H → eτ and H → μτ , respectively.publishedVersio
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