65 research outputs found

    INSTALLATION OF THE LHC EXPERIMENTAL INSERTIONS

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    The installation of the LHC experimental insertions, and particularly the installation of the Low-Beta quadrupoles, raises many technical challenges due to the stringent alignment specifications and to the difficulty of access in very confined areas. The compact layout with many lattice elements, vacuum components, beam control instrumentation and the presence of shielding does not allow for any improvisation in the installation procedure. This paper reviews all the constraints that need to be taken into account when installing the experimental insertions. It describes the chronological sequence of installation and discusses the technical solutions that have been adopted

    Design of the 70 mm twin aperture superconducting quadrupole for the LHC dump insertion

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    The LHC dump insertion features a pair of superconducting quadrupoles located on either side of a 340 m long straight section. Two horizontally deflecting kickers, located in between the quadrupole pairs, and a septum in the centre of the insertion, vertically deflect the two counter-rotating beams past the quadrupoles on the downstream sides, and into the dump areas. Due to the layout, the optical ß function in the quadrupoles is around 640 m, the largest around the LHC at injection. The quadrupoles must therefore have enlarged aperture and specially designed cryostats to allow for the safe passage of both the circulating and ejected beams. In this paper we present the design of the twin aperture dump quadrupole based on the 70 mm four layer coil proposed for the LHC low-ß quadrupoles. In preparation for model construction, we report on improvements of the coil design and a study of the retaining structures

    Association Between Frailty and Atrial Fibrillation in Older Adults: The Framingham Heart Study Offspring Cohort

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    Background: Frailty is associated bidirectionally with cardiovascular disease. However, the relations between frailty and atrial fibrillation (AF) have not been fully elucidated. Methods and Results: Using the FHS (Framingham Heart Study) Offspring cohort, we sought to examine both the association between frailty (2005-2008) and incident AF through 2016 and the association between prevalent AF and frailty status (2011-2014). Frailty was defined using the Fried phenotype. Models adjusted for age, sex, and smoking. Cox proportional hazards models, adjusted for competing risk of death, assessed the association between prevalent frailty and incident AF. Logistic regression models assessed the association between prevalent AF and new-onset frailty. For the incident AF analysis, we included 2053 participants (56% women; mean age, 69.7+/-6.9 years). By Fried criteria, 1018 (50%) were robust, 903 (44%) were prefrail, and 132 (6%) were frail. In total, 306 incident cases of AF occurred during an average 9.2 (SD, 3.1) follow-up years. After adjustment, there was no statistically significant association between prevalent frailty status and incident AF (prefrail versus robust: hazard ratio [HR], 1.22 [95% CI, 0.95-1.55]; frail versus robust: HR, 0.92 [95% CI, 0.57-1.47]). At follow-up, there were 111 new cases of frailty. After adjustment, there was no statistically significant association between prevalent AF and new-onset frailty (odds ratio, 0.48 [95% CI, 0.17-1.36]). Conclusions: Although a bidirectional association between frailty and cardiovascular disease has been suggested, we did not find evidence of an association between frailty and AF. Our findings may be limited by sample size and should be further explored in other populations

    Lifetime risk of atrial fibrillation according to optimal, borderline, or elevated levels of risk factors: cohort study based on longitudinal data from the Framingham Heart Study

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    OBJECTIVE: To examine the association between risk factor burdens-categorized as optimal, borderline, or elevated-and the lifetime risk of atrial fibrillation. DESIGN: Community based cohort study. SETTING: Longitudinal data from the Framingham Heart Study. PARTICIPANTS: Individuals free of atrial fibrillation at index ages 55, 65, and 75 years were assessed. Smoking, alcohol consumption, body mass index, blood pressure, diabetes, and history of heart failure or myocardial infarction were assessed as being optimal (that is, all risk factors were optimal), borderline (presence of borderline risk factors and absence of any elevated risk factor), or elevated (presence of at least one elevated risk factor) at index age. MAIN OUTCOME MEASURE: Lifetime risk of atrial fibrillation at index age up to 95 years, accounting for the competing risk of death. RESULTS: At index age 55 years, the study sample comprised 5338 participants (2531 (47.4%) men). In this group, 247 (4.6%) had an optimal risk profile, 1415 (26.5%) had a borderline risk profile, and 3676 (68.9%) an elevated risk profile. The prevalence of elevated risk factors increased gradually when the index ages rose. For index age of 55 years, the lifetime risk of atrial fibrillation was 37.0% (95% confidence interval 34.3% to 39.6%). The lifetime risk of atrial fibrillation was 23.4% (12.8% to 34.5%) with an optimal risk profile, 33.4% (27.9% to 38.9%) with a borderline risk profile, and 38.4% (35.5% to 41.4%) with an elevated risk profile. Overall, participants with at least one elevated risk factor were associated with at least 37.8% lifetime risk of atrial fibrillation. The gradient in lifetime risk across risk factor burden was similar at index ages 65 and 75 years. CONCLUSIONS: Regardless of index ages at 55, 65, or 75 years, an optimal risk factor profile was associated with a lifetime risk of atrial fibrillation of about one in five; this risk rose to more than one in three a third in individuals with at least one elevated risk factor

    A Validated Risk Prediction Model for Breast Cancer in US Black Women

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    PURPOSE Breast cancer risk prediction models are used to identify high-risk women for early detection, targeted interventions, and enrollment into prevention trials. We sought to develop and evaluate a risk prediction model for breast cancer in US Black women, suitable for use in primary care settings. METHODS Breast cancer relative risks and attributable risks were estimated using data from Black women in three US population-based case-control studies (3,468 breast cancer cases; 3,578 controls age 30-69 years) and combined with SEER age- and race-specific incidence rates, with incorporation of competing mortality, to develop an absolute risk model. The model was validated in prospective data among 51,798 participants of the Black Women’s Health Study, including 1,515 who developed invasive breast cancer. A second risk prediction model was developed on the basis of estrogen receptor (ER)–specific relative risks and attributable risks. Model performance was assessed by calibration (expected/observed cases) and discriminatory accuracy (C-statistic). RESULTS The expected/observed ratio was 1.01 (95% CI, 0.95 to 1.07). Age-adjusted C-statistics were 0.58 (95% CI, 0.56 to 0.59) overall and 0.63 (95% CI, 0.58 to 0.68) among women younger than 40 years. These measures were almost identical in the model based on estrogen receptor–specific relative risks and attributable risks. CONCLUSION Discriminatory accuracy of the new model was similar to that of the most frequently used questionnaire-based breast cancer risk prediction models in White women, suggesting that effective risk stratification for Black women is now possible. This model may be especially valuable for risk stratification of young Black women, who are below the ages at which breast cancer screening is typically begun

    Positive Study on the Tactics How to Tackle Section 337 Investigation in USA —— From the Answer Examples of Chinese Export Enterprises

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    当前美国337条款调查已经成为中国出口产品进入美国市场的重要障碍。本文以中国出口企业历年来的应诉实例为切入点,探讨这些案例所反映的调查特征,发现存在的主要问题,结合法律规定和具体案例研究“337调查”程序与实体方面的应对策略,从具体案例中吸取教训,总结经验。取材主要是涉中案例,更具说服力,特别是成功案例,希望借此增强国内企业应诉的信心。 除前言和结论外,本文共分四章,主要内容如下: 第一章介绍了中国出口企业应诉美国“337调查”的现状和存在的问题。详细统计了历年来中国企业的出庭情况,案件的审理结果以及产生这些结果的主要原因。虽然整体来看,中国企业的应对情况并不理想,但出庭案件绝大部分都没有...Currently Section 337 investigation of USA has already become an obstacle to Chinese products to enter into American market. The text takes the answer examples of Chinese enterprises as cut-in point, discusses the character and problems reflecting from these cases, combines rules of law and case study to research the countermeasures about procedure and entity aspects of Section 337 Investigation, ...学位:法学硕士院系专业:法学院法律系_民商法学(含劳动法学、社会保障法学)学号:20040804

    Renal artery stenosis-when to screen, what to stent?

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    Renal artery stensosis (RAS) continues to be a problem for clinicians, with no clear consensus on how to investigate and assess the clinical significance of stenotic lesions and manage the findings. RAS caused by fibromuscular dysplasia is probably commoner than previously appreciated, should be actively looked for in younger hypertensive patients and can be managed successfully with angioplasty. Atheromatous RAS is associated with increased incidence of cardiovascular events and increased cardiovascular mortality, and is likely to be seen with increasing frequency. Evidence from large clinical trials has led clinicians away from recommending interventional revascularisation towards aggressive medical management. There is now interest in looking more closely at patient selection for intervention, with focus on intervening only in patients with the highest-risk presentations such as flash pulmonary oedema, rapidly declining renal function and severe resistant hypertension. The potential benefits in terms of improving hard cardiovascular outcomes may outweigh the risks of intervention in this group, and further research is needed

    Impact of Reporting Bias in Network Meta-Analysis of Antidepressant Placebo-Controlled Trials

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    BACKGROUND: Indirect comparisons of competing treatments by network meta-analysis (NMA) are increasingly in use. Reporting bias has received little attention in this context. We aimed to assess the impact of such bias in NMAs. METHODS: We used data from 74 FDA-registered placebo-controlled trials of 12 antidepressants and their 51 matching publications. For each dataset, NMA was used to estimate the effect sizes for 66 possible pair-wise comparisons of these drugs, the probabilities of being the best drug and ranking the drugs. To assess the impact of reporting bias, we compared the NMA results for the 51 published trials and those for the 74 FDA-registered trials. To assess how reporting bias affecting only one drug may affect the ranking of all drugs, we performed 12 different NMAs for hypothetical analysis. For each of these NMAs, we used published data for one drug and FDA data for the 11 other drugs. FINDINGS: Pair-wise effect sizes for drugs derived from the NMA of published data and those from the NMA of FDA data differed in absolute value by at least 100% in 30 of 66 pair-wise comparisons (45%). Depending on the dataset used, the top 3 agents differed, in composition and order. When reporting bias hypothetically affected only one drug, the affected drug ranked first in 5 of the 12 NMAs but second (n = 2), fourth (n = 1) or eighth (n = 2) in the NMA of the complete FDA network. CONCLUSIONS: In this particular network, reporting bias biased NMA-based estimates of treatments efficacy and modified ranking. The reporting bias effect in NMAs may differ from that in classical meta-analyses in that reporting bias affecting only one drug may affect the ranking of all drugs

    Extent of non-publication in cohorts of studies approved by research ethics committees or included in trial registries

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    Background: The synthesis of published research in systematic reviews is essential when providing evidence to inform clinical and health policy decisionmaking. However, the validity of systematic reviews is threatened if journal publications represent a biased selection of all studies that have been conducted (dissemination bias). To investigate the extent of dissemination bias we conducted a systematic review that determined the proportion of studies published as peerreviewed journal articles and investigated factors associated with full publication in cohorts of studies (i) approved by research ethics committees (RECs) or (ii) included in trial registries. Copyright:Methods and Findings: Four bibliographic databases were searched for methodological research projects (MRPs) without limitations for publication year, language or study location. The searches were supplemented by handsearching the references of included MRPs. We estimated the proportion of studies published using prediction intervals (PI) and a random effects meta-analysis. Pooled odds ratios (OR) were used to express associations between study characteristics and journal publication. Seventeen MRPs (23 publications) evaluated cohorts of studies approved by RECs; the proportion of published studies had a PI between 22% and 72% and the weighted pooled proportion when combining estimates would be 46.2% (95% CI 40.2%-52.4%, I2594.4%). Twenty-two MRPs (22 publications) evaluated cohorts of studies included in trial registries; the PI of the proportion published ranged from 13% to 90% and the weighted pooled proportion would be 54.2% (95% CI 42.0%-65.9%, I2598.9%). REC-approved studies with statistically significant results (compared with those without statistically significant results) were more likely to be published (pooled OR 2.8; 95% CI 2.2-3.5). Phase-III trials were also more likely to be published than phase II trials (pooled OR 2.0; 95% CI 1.6- 2.5). The probability of publication within two years after study completion ranged from 7% to 30%.Conclusions: A substantial part of the studies approved by RECs or included in trial registries remains unpublished. Due to the large heterogeneity a prediction of the publication probability for a future study is very uncertain. Non-publication of research is not a random process, e.g., it is associated with the direction of study findings. Our findings suggest that the dissemination of research findings is biased
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