762 research outputs found

    Zeeman Slowers for Strontium based on Permanent Magnets

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    We present the design, construction, and characterisation of longitudinal- and transverse-field Zeeman slowers, based on arrays of permanent magnets, for slowing thermal beams of atomic Sr. The slowers are optimised for operation with deceleration related to the local laser intensity (by the parameter ϵ\epsilon), which uses more effectively the available laser power, in contrast to the usual constant deceleration mode. Slowing efficiencies of up to ≈\approx 1818 % are realised and compared to those predicted by modelling. We highlight the transverse-field slower, which is compact, highly tunable, light-weight, and requires no electrical power, as a simple solution to slowing Sr, well-suited to spaceborne application. For 88^{88}Sr we achieve a slow-atom flux of around 6×1096\times 10^9 atoms \,s−1^{-1} at 3030 ms−1^{-1}, loading approximately 5×1085\times 10^8 atoms in to a magneto-optical-trap (MOT), and capture all isotopes in approximate relative natural abundances

    Characterization of Milk Constituents of \u3ci\u3eBos Taurus\u3c/i\u3e and \u3ci\u3eBos Indicus\u3c/i\u3e × \u3ci\u3eBos Taurus\u3c/i\u3e Breed Types

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    Milk from eight Bos Taurus and Bos indicus × Bos Taurus breed types (n=128) was evaluated for percentage butterfat, protein, lactose and solids- non-fat. Milk samples were collected at approximately 60, 105, and 150 d after the onset of lactation by hand-milking the left front quarter following a 30-IU injection of oxytocin. Breed type variation was significant for some milk component traits at each stage of lactation. Brahman × Angus dams increased in component yields (kg) as lactation progressed; production levels of other breed types remained approximately the same or declined. Sex of calf influenced (P\u3c.05) yield (kg) of protein, butterfat and solids-non-fat at 105 d only. Mastitis effects caused a reduction (P\u3c.01) in percentage of lactose. Residual correlations between yield (kg) of milk components and weaning weight were all positive and significant

    A Randomized Trial Evaluating a Parent Based Intervention to Reduce College Drinking

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    This study evaluated the effectiveness of a parent based intervention (PBI) in reducing drinking among first year college students (N = 443). Students were assigned to one of three conditions: PBI, PBI plus booster brochures (PBI-B), and an assessment only control group (CNT). At a 4-month post-intervention follow-up, results indicated students in the PBI-B group reported significantly less drinking to intoxication and peak drinking relative to the PBI group and CNT group. No significant differences were found between the PBI group and CNT group. Results provide further support for PBIs to reduce college student drinking and suggest that a booster brochure increases the effectiveness of PBIs

    Chronic viral infection promotes sustained Th1-derived immunoregulatory IL-10 via BLIMP-1

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    During the course of many chronic viral infections, the antiviral T cell response becomes attenuated through a process that is regulated in part by the host. While elevated expression of the immunosuppressive cytokine IL-10 is involved in the suppression of viral-specific T cell responses, the relevant cellular sources of IL-10, as well as the pathways responsible for IL-10 induction, remain unclear. In this study, we traced IL-10 production over the course of chronic lymphocytic choriomeningitis virus (LCMV) infection in an IL-10 reporter mouse line. Using this model, we demonstrated that virus-specific T cells with reduced inflammatory function, particularly Th1 cells, display elevated and sustained IL-10 expression during chronic LCMV infection. Furthermore, ablation of IL-10 from the T cell compartment partially restored T cell function and reduced viral loads in LCMV-infected animals. We found that viral persistence is needed for sustained IL-10 production by Th1 cells and that the transcription factor BLIMP-1 is required for IL-10 expression by Th1 cells. Restimulation of Th1 cells from LCMV-infected mice promoted BLIMP-1 and subsequent IL-10 expression, suggesting that constant antigen exposure likely induces the BLIMP-1/IL-10 pathway during chronic viral infection. Together, these data indicate that effector T cells self-limit their responsiveness during persistent viral infection via an IL-10-dependent negative feedback loop.This work was supported by an Australian NHMRC Overseas Biomedical Postdoctoral Fellowship (to I.A. Parish); a Yale School of Medicine Brown-Coxe Postdoctoral Fellowship (to I.A. Parish); the Alexander von Humboldt Foundation (SKA2010, to P.A. Lang); a CIHR grant (to P.S. Ohashi); and by the Howard Hughes Medical Institute and NIH grant RO1AI074699 (to S.M. Kaech). P.S. Ohashi holds a Canada Research Chair in Autoimmunity and Tumor immunity

    Microvolt T-Wave Alternans and the Risk of Death or Sustained Ventricular Arrhythmias in Patients With Left Ventricular Dysfunction

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    ObjectivesThis study hypothesized that microvolt T-wave alternans (MTWA) improves selection of patients for implantable cardioverter-defibrillator (ICD) prophylaxis, especially by identifying patients who are not likely to benefit.BackgroundMany patients with left ventricular dysfunction are now eligible for prophylactic ICDs, but most eligible patients do not benefit; MTWA testing has been proposed to improve patient selection.MethodsOur study was conducted at 11 clinical centers in the U.S. Patients were eligible if they had a left ventricular ejection fraction (LVEF) ≤0.40 and lacked a history of sustained ventricular arrhythmias; patients were excluded for atrial fibrillation, unstable coronary artery disease, or New York Heart Association functional class IV heart failure. Participants underwent an MTWA test and then were followed for about two years. The primary outcome was all-cause mortality or non-fatal sustained ventricular arrhythmias.ResultsIschemic heart disease was present in 49%, mean LVEF was 0.25, and 66% had an abnormal MTWA test. During 20 ± 6 months of follow-up, 51 end points (40 deaths and 11 non-fatal sustained ventricular arrhythmias) occurred. Comparing patients with normal and abnormal MTWA tests, the hazard ratio for the primary end point was 6.5 at two years (95% confidence interval 2.4 to 18.1, p < 0.001). Survival of patients with normal MTWA tests was 97.5% at two years. The strong association between MTWA and the primary end point was similar in all subgroups tested.ConclusionsAmong patients with heart disease and LVEF ≤0.40, MTWA can identify not only a high-risk group, but also a low-risk group unlikely to benefit from ICD prophylaxis

    B(E1) Strengths from Coulomb Excitation of 11Be

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    The BB(E1;1/2+→1/2−1/2^+\to1/2^-) strength for 11^{11}Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the excitation cross section for 11^{11}Be+208^{208}Pb at 38.6 MeV/nucleon is reported. The BB(E1) strength of 0.105(12) e2^2fm2^2 derived from this measurement is consistent with those made previously at 60 and 64 MeV/nucleon, i n contrast to an anomalously low result obtained at 43 MeV/nucleon. By coupling a multi-configuration description of the projectile structure with realistic reaction theory, the XCDCC model provides for the first time a fully quantum mechanical description of Coulomb excitation. The XCDCC calculations reveal that the excitation process involves significant contributions from nuclear, continuum, and higher-order effects. An analysis of the present and two earlier intermediate energy measurements yields a combined B(E1) strength of 0.105(7) e2^2fm2^2. This value is in good agreement with the value deduced independently from the lifetime of the 1/2−1/2^- state in 11^{11}Be, and has a comparable p recision.Comment: 5 pages, 2 figures, accepted for publication in Phys. Lett.

    PrEP use and unmet PrEP-need among men who have sex with men in London prior to the implementation of a national PrEP programme, a cross-sectional study from June to August 2019

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    BACKGROUND: Access to prevention options, including HIV pre-exposure prophylaxis (PrEP), remains a public health priority for gay, bisexual, and other men who have sex with men (MSM), especially in London. We describe PrEP use in a London community sample of MSM before the introduction of a national PrEP programme in October 2020. METHODS: From June-August 2019, MSM aged ≥ 18 recruited from London commercial venues were asked to self-complete a sexual health questionnaire and provide an oral fluid sample for anonymous HIV antibody testing. Descriptive analyses of demographic characteristics, service engagement and outcomes, as well as sexual risk and prevention behaviours were examined in the survey population and in those reporting current PrEP use. We performed sequential, multivariate analyses examining current PrEP use in MSM of self-perceived HIV-negative/unknown status with identified PrEP-need defined as the report of condomless anal sex (CAS) in the last three months, or the report of CAS (in the last year) with an HIV-positive/unknown status partner not known to be on HIV treatment, in reflection of UK PrEP guidelines. RESULTS: One thousand five hundred and thirty-fifth questionnaires were completed across 34 venues, where 1408 were analysed. One in five MSM of self-perceived HIV-negative/unknown status reported current PrEP use (19.7%, 242/1230). In men with PrEP-need, 68.2% (431/632) did not report current use. Current PrEP use was associated with age (aOR: 3.52, 95% CI: 1.76-7.02 in men aged 40-44 vs men aged 18-25) and education (aOR: 1.72, 95% CI: 1.01-2.92 in men with ≥ 2 years/still full-time vs no/ < 2 years of education since age 16). CONCLUSION: Among MSM in London, PrEP use is high but there is indication of unmet PrEP-need in men of younger age and lower levels of post-16 education. National programme monitoring and evaluation will require continued community monitoring to guide interventions ensuring equitable PrEP access and uptake in those who could most benefit from PrEP
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