206 research outputs found

    A Helium-Surface Interaction Potential of Bi2_2Te3_3(111) from Ultrahigh-Resolution Spin-Echo Measurements

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    We have determined an atom-surface interaction potential for the He-Bi2_2Te3_3(111) system by analysing ultrahigh resolution measurements of selective adsorption resonances. The experimental measurements were obtained using 3^3He spin-echo spectrometry. Following an initial free-particle model analysis, we use elastic close-coupling calculations to obtain a three-dimensional potential. The three-dimensional potential is then further refined based on the experimental data set, giving rise to an optimised potential which fully reproduces the experimental data. Based on this analysis, the He-Bi2_2Te3_3(111) interaction potential can be described by a corrugated Morse potential with a well depth D=(6.22±0.05) meVD=(6.22\pm0.05)~\mathrm{meV}, a stiffness κ=(0.92±0.01) A˚1\kappa =(0.92\pm0.01)~\mathrm{\AA}^{-1} and a surface electronic corrugation of (9.6±0.2)(9.6\pm0.2)% of the lattice constant. The improved uncertainties of the atom-surface interaction potential should also enable the use in inelastic close-coupled calculations in order to eventually study the temperature dependence and the line width of selective adsorption resonances

    Waiting time distribution in public health care: empirics and theory

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    Excessive waiting times for elective surgery have been a long-standing concern in many national healthcare systems in the OECD. How do the hospital admission patterns that generate waiting lists affect different patients? What are the hospitals characteristics that determine waiting times? By developing a model of healthcare provision and analysing empirically the entire waiting time distribution we attempt to shed some light on those issues. We first build a theoretical model that describes the optimal waiting time distribution for capacity constraint hospitals. Secondly, employing duration analysis, we obtain empirical representations of that distribution across hospitals in the UK from 1997–2005. We observe important differences on the ‘scale’ and on the ‘shape’ of admission rates. Scale refers to how quickly patients are treated and shape represents trade-offs across duration-treatment profiles. By fitting the theoretical to the empirical distributions we estimate the main structural parameters of the model and are able to closely identify the main drivers of these empirical differences. We find that the level of resources allocated to elective surgery (budget and physical capacity), which determines how constrained the hospital is, explains differences in scale. Changes in benefits and costs structures of healthcare provision, which relate, respectively, to the desire to prioritise patients by duration and the reduction in costs due to delayed treatment, determine the shape, affecting short and long duration patients differently

    Herd-level risk factors associated with Leptospira Hardjo seroprevalence in Beef/Suckler herds in the Republic of Ireland

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    <p>Abstract</p> <p>Background</p> <p>The aim of the present study was to investigate risk factors for herd seropositivity to <it>Leptospira </it>Hardjo in Irish suckler herds. Herds were considered eligible for the study if they were unvaccinated and contained ≥ 9 breeding animals of beef breed which were ≥ 12 months of age. The country was divided into six regions using county boundaries. Herd and individual animal prevalence data were available from the results of a concurrent seroprevalence study. Herds were classified as either "Free from Infection" or "Infected" based on a minimum expected 40% within-herd prevalence.</p> <p>Questionnaires were posted to 320 farmers chosen randomly from 6 regions, encompassing 25 counties, of the Republic of Ireland. The questionnaire was designed to obtain information about vaccination; reproductive disease; breeding herd details; the presence of recognized risk factors from previous studies; and husbandry on each farm. Data collected from 128 eligible herds were subjected to statistical analysis.</p> <p>Results</p> <p>Following the use of Pearson's Chi-Square Test, those variables associated with a herd being "infected" with a significance level of P < 0.2 were considered as candidates for multivariable logistic regression modelling. Breeding herd size was found to be a statistically significant risk factor after multivariable logistic regression. The odds of a herd being positive for leptospiral infection were 5.47 times higher (P = 0.032) in herds with 14 to 23 breeding animals compared with herds with ≤ 13 breeding animals, adjusting for Region, and 7.08 times higher (P = 0.033) in herds with 32.6 to 142 breeding animals.</p> <p>Conclusions</p> <p>Breeding herd size was identified as a significant risk factor for leptospiral infection in Irish suckler herds, which was similar to findings of previous studies of leptospirosis in dairy herds.</p

    Factors Associated with Bovine Neonatal Pancytopenia (BNP) in Calves: A Case-Control Study

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    Bovine neonatal pancytopenia (BNP; previously known as idiopathic haemorrhagic diathesis and commonly known as bleeding calf syndrome) is a novel haemorrhagic disease of young calves which has emerged in a number of European countries during recent years. Data were retrospectively collected during June to November 2010 for 56 case calves diagnosed with BNP between 17 March and 7 June of the same year. These were compared with 58 control calves randomly recruited from herds with no history of BNP. Multivariable logistic regression analysis showed that increased odds of a calf being a BNP case were associated with its dam having received PregSure® BVD (Pfizer Animal Health) vaccination prior to the birth of the calf (odds ratio (OR) 40.78, p<0.001) and its herd of origin being located in Scotland (OR 9.71, p = 0.006). Decreased odds of a calf being a BNP case were associated with the calf having been kept outside (OR 0.11, p = 0.006). The longer that a cattle herd had been established on the farm was also associated with decreased odds of a calf in that herd being a BNP case (OR 0.97, p = 0.011)

    Geographic determinants of reported human Campylobacter infections in Scotland

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    &lt;p&gt;&lt;b&gt;Background:&lt;/b&gt; Campylobacteriosis is the leading cause of bacterial gastroenteritis in most developed countries. People are exposed to infection from contaminated food and environmental sources. However, the translation of these exposures into infection in the human population remains incompletely understood. This relationship is further complicated by differences in the presentation of cases, their investigation, identification, and reporting; thus, the actual differences in risk must be considered alongside the artefactual differences.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methods:&lt;/b&gt; Data on 33,967 confirmed Campylobacter infections in mainland Scotland between 2000 and 2006 (inclusive) that were spatially referenced to the postcode sector level were analysed. Risk factors including the Carstairs index of social deprivation, the easting and northing of the centroid of the postcode sector, measures of livestock density by species and population density were tested in univariate screening using a non-spatial generalised linear model. The NHS Health Board of the case was included as a random effect in this final model. Subsequently, a spatial generalised linear mixed model (GLMM) was constructed and age-stratified sensitivity analysis was conducted on this model.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Results:&lt;/b&gt; The spatial GLMM included the protective effects of the Carstairs index (relative risk (RR) = 0.965, 95% Confidence intervals (CIs) = 0.959, 0.971) and population density (RR = 0.945, 95% CIs = 0.916, 0.974. Following stratification by age group, population density had a significant protective effect (RR = 0.745, 95% CIs = 0.700, 0.792) for those under 15 but not for those aged 15 and older (RR = 0.982, 95% CIs = 0.951, 1.014). Once these predictors have been taken into account three NHS Health Boards remain at significantly greater risk (Grampian, Highland and Tayside) and two at significantly lower risk (Argyll and Ayrshire and Arran).&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusions:&lt;/b&gt; The less deprived and children living in rural areas are at the greatest risk of being reported as a case of Campylobacter infection. However, this analysis cannot differentiate between actual risk and heterogeneities in individual reporting behaviour; nevertheless this paper has demonstrated that it is possible to explain the pattern of reported Campylobacter infections using both social and environmental predictors.&lt;/p&gt

    Иммунно-нейроэндокринные взаимосвязи в развитии перименопаузальной патологии

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    Представлен современный патогенетический взгляд на происходящие в перименопаузальном периоде системные нарушения. Показано, что имунно-нейроэндокринный гомеостаз имеет определенные отличия в зависимости от клинической формы и степени тяжести перименопаузальных нарушений, что необходимо учитывать при проведении терапевтических мероприятий.Представлено сучасний патогенетичний погляд на системні порушення, що відбуваються в перименопаузальному періоді. Показано, що імунно-нейроендокринний гомеостаз має певні відмінності залежно від клінічної форми і ступеня тяжкості перименопаузальних порушень, що необхідно враховувати під час проведення терапевтичних заходів.A modern pathogenetic opinion about the systemic perimenopausal disorders is presented. It is shown that immunoneuroendocrine homeostatsis differs depending on the clinical form and degree of severity of perimenopausal disorders, which should be taken into consideration when taking therapeutic measures
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