2,441 research outputs found

    The distribution and breeding performance of the buzzard Buteo buteo in relation to habitat: an application using remote sensing and Geographical Information Systems

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    The British uplands support a rich assemblage of a number of predatory and scavenging birds, including golden eagle, merlin, red kite, hen harrier, raven and buzzard, with nationally and internationally important populations of some of these species. A feature all these species have in common is the requirement for large foraging ranges by individuals which means that large tracts of suitable habitat are necessary to support viable populations. Current changes in upland land use such as afforestation and changing agricultural practices give cause for concern. The conservation of these species and others like them requires a greater understanding of how these birds interact with the landscape and how their distribution and breeding performance reflects their habitat. Ecologists are becoming increasingly aware of the potential of Geographical Information Systems (GIS) for exploring these relationships between animal species and their habitat. In this thesis, the buzzard was chosen as a model species to explore ways of predicting bird distributions and breeding performance from readily available data using GIS. This study was carried out in mid-Argyll, Scotland. The distribution and breeding performance of buzzards was determined for a number of study areas, chosen to represent the full spectrum of habitats to be encountered in mid-Argyll, during 1989 and 1990. Parameters of breeding performance used were laying date, clutch size, initial brood size and fledging success. Brood quality was also assessed, based on nestling growth. The breeding performance of buzzards in mid-Argyll was included in a comparison of published data from studies elsewhere in Britain. Laying dates were found to be consistent throughout the country while clutch size, initial brood size and fledging success were seen to differ between studies. No patterns which might relate to latitudinal or climatic trends were apparent and differences were considered to be due to overall habitat differences between the regions considered. While buzzards in mid-Argyll tended to produce low clutch sizes the population as a whole showed high fledging success. While buzzards nestlings in mid-Argyll had good survival rates the high fledging success is probably best explained by absence of human interference, malicious or otherwise in this area. An important consideration when looking at the distribution of a bird size such as the buzzard is whether this might be influenced by nest site availability. Buzzards in mid-Argyll used a number of distinct nest site habitats. While the majority of buzzards nested in trees, a substantial proportion were found nesting on steep banks and crags. Considering the adaptability of buzzards in their choice of nest site and the abundance of acceptable sites it was considered that the availability of potential nest sites was unlikely to influence buzzard distribution in mid-Argyll

    Houve um holocausto chileno? Campos de concentração, genocídio político e a ditadura de Pinochet

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    This essay discusses the Pinochet Dictatorship’s human rights violations. We argue that the Chilean military’s torture, disappearance, and execution of a significant part of its population, with development of a State terrorism and institutionalized racist practices constitute a holocaust. The U.S.-sponsored military regime killed with an allconsuming ideological obsession, and displayed a bureaucratic dedication to eliminating communism.Este ensaio discute as violações de direitos humanos na ditadura Pinochet. Argumentamos que a tortura, desaparecimento e execução de milhares de chilenos pelos militares, com implantação de terrorismo de Estado e práticas racistas institucionalizadas, constituem um “holocausto”. Patrocinado pelos EUA, o regime militar matou com uma obsessão ideológica destruidora e mostrou eficiência burocrática para eliminar o comunismo

    The Marco Gonzalez Maya site, Ambergris Caye, Belize: assessing the impact of human activities by examining diachronic processes at the local scale

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    Research at the Maya archaeological site of Marco Gonzalez on Ambergris Caye in Belize is socio-ecological because human activities have been a factor in the formation and fluctuation of the local marine and terrestrial environments over time. The site is one of many on Belize's coast and cayes that exhibit anomalous vegetation and dark-coloured soils. These soils, although sought for cultivation, are not typical 'Amazonian Dark Earths' but instead are distinctive to the weathering of carbonate-rich anthropogenic deposits. We tentatively term these location-specific soils as Maya Dark Earths. Our research seeks to quantify the role of human activities in long-term environmental change and to develop strategies, specifically Life Cycle Assessment (LCA), that can be applied to environmental impact modelling today

    Selection for Increased Natural Antibody Levels to Improve Disease Resilience in Pigs

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    Breeding animals are typically raised under high health conditions in nucleus herds, but their offspring are often exposed to multiple disease challenges in commercial production facilities. Because breeding animals are not exposed to many common swine pathogens, it is difficult to select for resilience to disease. A possible solution is selecting for levels of natural antibodies (NAb), which can be measured in a high health environment and in this study are shown to correlate with disease resilience and to be heritable (h2 = 0.11 to 0.39). Therefore, breeding for increased NAb levels in clean conditions could be a valuable method to improve resilience and decrease mortality in market pigs. Work is ongoing to verify the potential of this prediction

    Correlations in Cosmic String Networks

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    We investigate scaling and correlations of the energy and momentum in an evolving network of cosmic strings in Minkowski space. These quantities are of great interest, as they must be understood before accurate predictions for the power spectra of the perturbations in the matter and radiation in the early Universe can be made. We argue that Minkowski space provides a reasonable approximation to a Friedmann background for string dynamics and we use our results to construct a simple model of the network, in which it is considered to consist of randomly placed segments moving with random velocities. This model works well in accounting for features of the two-time correlation functions, and even better for the power spectra.Comment: 20pp Plain LaTeX, 11 EPS figures, uses epsf.st

    Diet and physical activity in pregnancy to prevent gestational diabetes:A protocol for an individual participant data (IPD) meta-analysis on the differential effects of interventions with economic evaluation

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    Introduction: Mothers with gestational diabetes mellitus (GDM) are at increased risk of pregnancy-related complications and developing type 2 diabetes after delivery. Diet and physical activity-based interventions may prevent GDM, but variations in populations, interventions and outcomes in primary trials have limited the translation of available evidence into practice. We plan to undertake an individual participant data (IPD) meta-analysis of randomised trials to assess the differential effects and cost-effectiveness of diet and physical activity-based interventions in preventing GDM and its complications. Methods: The International Weight Management in Pregnancy Collaborative Network database is a living repository of IPD from randomised trials on diet and physical activity in pregnancy identified through a systematic literature search. We shall update our existing search on MEDLINE, Embase, BIOSIS, LILACS, Pascal, Science Citation Index, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects and Health Technology Assessment Database without language restriction to identify relevant trials until March 2021. Primary researchers will be invited to join the Network and share their IPD. Trials including women with GDM at baseline will be excluded. We shall perform a one and two stage random-effect meta-analysis for each intervention type (all interventions, diet-based, physical activity-based and mixed approach) to obtain summary intervention effects on GDM with 95% CIs and summary treatment–covariate interactions. Heterogeneity will be summarised using I2 and tau2 statistics with 95% prediction intervals. Publication and availability bias will be assessed by examining small study effects. Study quality of included trials will be assessed by the Cochrane Risk of Bias tool, and the Grading of Recommendations, Assessment, Development and Evaluations approach will be used to grade the evidence in the results. A model-based economic analysis will be carried out to assess the cost-effectiveness of interventions to prevent GDM and its complications compared with usual care. Ethics and dissemination: Ethics approval is not required. The study is registered on the International Prospective Register of Systematic Reviews (CRD42020212884). Results will be submitted for publication in peer-reviewed journals

    The what and where of adding channel noise to the Hodgkin-Huxley equations

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    One of the most celebrated successes in computational biology is the Hodgkin-Huxley framework for modeling electrically active cells. This framework, expressed through a set of differential equations, synthesizes the impact of ionic currents on a cell's voltage -- and the highly nonlinear impact of that voltage back on the currents themselves -- into the rapid push and pull of the action potential. Latter studies confirmed that these cellular dynamics are orchestrated by individual ion channels, whose conformational changes regulate the conductance of each ionic current. Thus, kinetic equations familiar from physical chemistry are the natural setting for describing conductances; for small-to-moderate numbers of channels, these will predict fluctuations in conductances and stochasticity in the resulting action potentials. At first glance, the kinetic equations provide a far more complex (and higher-dimensional) description than the original Hodgkin-Huxley equations. This has prompted more than a decade of efforts to capture channel fluctuations with noise terms added to the Hodgkin-Huxley equations. Many of these approaches, while intuitively appealing, produce quantitative errors when compared to kinetic equations; others, as only very recently demonstrated, are both accurate and relatively simple. We review what works, what doesn't, and why, seeking to build a bridge to well-established results for the deterministic Hodgkin-Huxley equations. As such, we hope that this review will speed emerging studies of how channel noise modulates electrophysiological dynamics and function. We supply user-friendly Matlab simulation code of these stochastic versions of the Hodgkin-Huxley equations on the ModelDB website (accession number 138950) and http://www.amath.washington.edu/~etsb/tutorials.html.Comment: 14 pages, 3 figures, review articl

    Preventing Cardiac Damage in Patients Treated for Breast Cancer and Lymphoma: The PROACT Clinical Trial

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    \ua9 2024 The AuthorsBackground: Cardiotoxicity is a concern for cancer survivors undergoing anthracycline chemotherapy. Enalapril has been explored for its potential to mitigate cardiotoxicity in cancer patients. The dose-dependent cardiotoxicity effects of anthracyclines can be detected early through the biomarker cardiac troponin. Objectives: The PROACT (Preventing Cardiac Damage in Patients Treated for Breast Cancer and Lymphoma) clinical trial assessed the effectiveness of enalapril in preventing cardiotoxicity, manifesting as myocardial injury and cardiac function impairment, in patients undergoing high-dose anthracycline-based chemotherapy for breast cancer or non-Hodgkin lymphoma. Methods: This prospective, multicenter, open-label, randomized controlled trial employed a superiority design with observer-blinded endpoints. A total of 111 participants, scheduled for 6 cycles of chemotherapy with a planned dose of ≥300 mg/m2 doxorubicin equivalents, were randomized to receive either enalapril (titrated up to 20 mg daily) or standard care without enalapril. Results: Myocardial injury, indicated by cardiac troponin T (≥14 ng/L), during and 1 month after chemotherapy, was observed in 42 (77.8%) of 54 patients in the enalapril group vs 45 (83.3%) of 54 patients in the standard care group (OR: 0.65; 95% CI: 0.23-1.78). Injury detected by cardiac troponin I (>26.2 ng/L) occurred in 25 (47.2%) of 53 patients on enalapril compared with 24 (45.3%) of 53 in standard care (OR: 1.10; 95% CI: 0.50-2.38). A relative decline of more than 15% from baseline in left ventricular global longitudinal strain was observed in 10 (21.3%) of 47 patients on enalapril and 9 (21.9%) of 41 in standard care (OR: 0.95; 95% CI: 0.33-2.74). An absolute decline of >10% to <50% in left ventricular ejection fraction was seen in 2 (4.1%) of 49 patients on enalapril vs none in patients in standard care. Conclusions: Adding enalapril to standard care during chemotherapy did not prevent cardiotoxicity in patients receiving high-dose anthracycline-based chemotherapy. (PROACT: Can we prevent Chemotherapy-related Heart Damage in Patients With Breast Cancer and Lymphoma?; NCT03265574

    Wilson Lines and a Canonical Basis of SU(4) Heterotic Standard Models

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    The spontaneous breaking of SU(4) heterotic standard models by Z_3 x Z_3 Wilson lines to the MSSM with three right-handed neutrino supermultiplets and gauge group SU(3)_C x SU(2)_L x U(1) x U(1) is explored. The two-dimensional subspace of the Spin(10) Lie algebra that commutes with su(3)_C + su(2)_L is analyzed. It is shown that there is a unique basis for which the initial soft supersymmetry breaking parameters are uncorrelated and for which the U(1) x U(1) field strengths have no kinetic mixing at any scale. If the Wilson lines "turn on" at different scales, there is an intermediate regime with either a left-right or a Pati-Salam type model. We compute their spectra directly from string theory, and adjust the associated mass parameter so that all gauge parameters exactly unify. A detailed analysis of the running gauge couplings and soft gaugino masses is presented.Comment: 59 pages, 9 figure
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