988 resultados para heavy rainfall events
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We numerically simulate planar shock wave collisions in anti-de Sitter space as a model for heavy ion collisions of large nuclei. We uncover a crossover between two different dynamical regimes as a function of the collision energy. At low energies the shocks first stop and then explode in a manner approximately described by hydrodynamics, in close similarity with the Landau model. At high energies the receding fragments move outwards at the speed of light, with a region of negative energy density and negative longitudinal pressure trailing behind them. The rapidity distribution of the energy density at late times around midrapidity is not approximately boost invariant but Gaussian, albeit with a width that increases with the collision energy.
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OBJECTIVE: The objective was to determine the risk of stroke associated with subclinical hypothyroidism. DATA SOURCES AND STUDY SELECTION: Published prospective cohort studies were identified through a systematic search through November 2013 without restrictions in several databases. Unpublished studies were identified through the Thyroid Studies Collaboration. We collected individual participant data on thyroid function and stroke outcome. Euthyroidism was defined as TSH levels of 0.45-4.49 mIU/L, and subclinical hypothyroidism was defined as TSH levels of 4.5-19.9 mIU/L with normal T4 levels. DATA EXTRACTION AND SYNTHESIS: We collected individual participant data on 47 573 adults (3451 subclinical hypothyroidism) from 17 cohorts and followed up from 1972-2014 (489 192 person-years). Age- and sex-adjusted pooled hazard ratios (HRs) for participants with subclinical hypothyroidism compared to euthyroidism were 1.05 (95% confidence interval [CI], 0.91-1.21) for stroke events (combined fatal and nonfatal stroke) and 1.07 (95% CI, 0.80-1.42) for fatal stroke. Stratified by age, the HR for stroke events was 3.32 (95% CI, 1.25-8.80) for individuals aged 18-49 years. There was an increased risk of fatal stroke in the age groups 18-49 and 50-64 years, with a HR of 4.22 (95% CI, 1.08-16.55) and 2.86 (95% CI, 1.31-6.26), respectively (p trend 0.04). We found no increased risk for those 65-79 years old (HR, 1.00; 95% CI, 0.86-1.18) or ≥ 80 years old (HR, 1.31; 95% CI, 0.79-2.18). There was a pattern of increased risk of fatal stroke with higher TSH concentrations. CONCLUSIONS: Although no overall effect of subclinical hypothyroidism on stroke could be demonstrated, an increased risk in subjects younger than 65 years and those with higher TSH concentrations was observed.
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It has been shown in recent ALICE@LHC measurements that the odd flow harmonics, in particular, a directed flow v1, occurred to be weak and dominated by random fluctuations. In this work we propose a new method, which makes the measurements more sensitive to the flow patterns showing global collective symmetries. We demonstrate how the longitudinal center of mass rapidity fluctuations can be identified, and then the collective flow analysis can be performed in the event-by-event center of mass frame. Such a method can be very effective in separating the flow patterns originating from random fluctuations, and the flow patterns originating from the global symmetry of the initial state.
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In this paper we consider a stochastic process that may experience random reset events which suddenly bring the system to the starting value and analyze the relevant statistical magnitudes. We focus our attention on monotonic continuous-time random walks with a constant drift: The process increases between the reset events, either by the effect of the random jumps, or by the action of the deterministic drift. As a result of all these combined factors interesting properties emerge, like the existence (for any drift strength) of a stationary transition probability density function, or the faculty of the model to reproduce power-law-like behavior. General formulas for two extreme statistics, the survival probability, and the mean exit time, are also derived. To corroborate in an independent way the results of the paper, Monte Carlo methods were used. These numerical estimations are in full agreement with the analytical predictions.
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Background: In longitudinal studies where subjects experience recurrent incidents over a period of time, such as respiratory infections, fever or diarrhea, statistical methods are required to take into account the within-subject correlation. Methods: For repeated events data with censored failure, the independent increment (AG), marginal (WLW) and conditional (PWP) models are three multiple failure models that generalize Cox"s proportional hazard model. In this paper, we revise the efficiency, accuracy and robustness of all three models under simulated scenarios with varying degrees of within-subject correlation, censoring levels, maximum number of possible recurrences and sample size. We also study the methods performance on a real dataset from a cohort study with bronchial obstruction. Results: We find substantial differences between methods and there is not an optimal method. AG and PWP seem to be preferable to WLW for low correlation levels but the situation reverts for high correlations. Conclusions: All methods are stable in front of censoring, worsen with increasing recurrence levels and share a bias problem which, among other consequences, makes asymptotic normal confidence intervals not fully reliable, although they are well developed theoretically.
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AIMS: The aims of the study are to compare the outcome with and without major bleeding and to identify the independent correlates of major bleeding complications and mortality in patients described in the ATOLL study. METHODS: The ATOLL study included 910 patients randomly assigned to either 0.5 mg/kg intravenous enoxaparin or unfractionated heparin before primary percutaneous coronary intervention. Incidence of major bleeding and ischemic end points was assessed at 1 month, and mortality, at 1 and 6 months. Patients with and without major bleeding complication were compared. A multivariate model of bleeding complications at 1 month and mortality at 6 months was realized. Intention-to-treat and per-protocol analyses were performed. RESULTS: The most frequent bleeding site appears to be the gastrointestinal tract. Age >75 years, cardiac arrest, and the use of insulin or >1 heparin emerged as independent correlates of major bleeding at 1 month. Patients presenting with major bleeding had significantly higher rates of adverse ischemic complications. Mortality at 6 months was higher in bleeders. Major bleeding was found to be one of the independent correlates of 6-month mortality. The addition or mixing of several anticoagulant drugs was an independent factor of major bleeding despite the predominant use of radial access. CONCLUSIONS: This study shows that major bleeding is independently associated with poor outcome, increasing ischemic events, and mortality in primary percutaneous coronary intervention performed mostly with radial access.
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AIM: To estimate the statistical interactions between alcohol policy strength and the person-related risk factors of sensation-seeking, antisocial personality disorder and attention-deficit/hyperactivity disorder related to heavy alcohol use. DESIGN: Cross-sectional survey. SETTING: Young Swiss men living within 21 jurisdictions across Switzerland. PARTICIPANTS: A total of 5701 Swiss men (mean age 20 years) participating in the Cohort Study on Substance Use Risk Factors (C-SURF). MEASUREMENTS: Outcome measures were alcohol use disorder (AUD) as defined in the DSM-5 and risky single-occasion drinking (RSOD). Independent variables were sensation-seeking, antisocial personality disorder (ASPD), attention-deficit/hyperactivity disorder (ADHD) and an index of alcohol policy strength. FINDINGS: Alcohol policy strength was protective against RSOD [odds ratio (OR) = 0.91 (0.84-0.99)], while sensation-seeking and ASPD were risk factors for both RSOD [OR = 1.90 (1.77-2.04); OR = 1.69 (1.44-1.97)] and AUD [OR = 1.58 (1.47-1.71); OR = 2.69 (2.30-3.14)] and ADHD was a risk factor for AUD [OR = 1.08 (1.06-1.10)]. Significant interactions between alcohol policy strength and sensation-seeking were identified for RSOD [OR = 1.06 (1.01-1.12)] and AUD [OR = 1.06 (1.01-1.12)], as well as between alcohol policy strength and ASPD for both RSOD [OR = 1.17 (1.03-1.31)] and AUD [OR = 1.15 (1.02-1.29)]. These interactions indicated that the protective effects of alcohol policy strength on RSOD and AUD were lost in men with high levels of sensation-seeking or an ASPD. No interactions were detected between alcohol policy strength and ADHD. CONCLUSION: Stronger alcohol legislation protects against heavy alcohol use in young Swiss men, but this protective effect is lost in individuals with high levels of sensation-seeking or having an antisocial personality disorder.
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Snow cover is an important control in mountain environments and a shift of the snow-free period triggered by climate warming can strongly impact ecosystem dynamics. Changing snow patterns can have severe effects on alpine plant distribution and diversity. It thus becomes urgent to provide spatially explicit assessments of snow cover changes that can be incorporated into correlative or empirical species distribution models (SDMs). Here, we provide for the first time a with a lower overestimation comparison of two physically based snow distribution models (PREVAH and SnowModel) to produce snow cover maps (SCMs) at a fine spatial resolution in a mountain landscape in Austria. SCMs have been evaluated with SPOT-HRVIR images and predictions of snow water equivalent from the two models with ground measurements. Finally, SCMs of the two models have been compared under a climate warming scenario for the end of the century. The predictive performances of PREVAH and SnowModel were similar when validated with the SPOT images. However, the tendency to overestimate snow cover was slightly lower with SnowModel during the accumulation period, whereas it was lower with PREVAH during the melting period. The rate of true positives during the melting period was two times higher on average with SnowModel with a lower overestimation of snow water equivalent. Our results allow for recommending the use of SnowModel in SDMs because it better captures persisting snow patches at the end of the snow season, which is important when modelling the response of species to long-lasting snow cover and evaluating whether they might survive under climate change.
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In the context of globalized competition among territories, cities, regions and countries have to find new ways to be attractive to companies, investors, tourists and residents. In that perspective, major sports events (such as the Olympic Games or the FIFA World Cup) are often seen as a lever for territorial development. Based on that idea, many sports events hosting strategies have emerged in the 1980s and 1990s. However, the growing competition in the sports events' market and the gigantism of those major events, forced some territories to turn to smaller events. This necessary resize of their strategy raises the question of their capacity to meet the initial objectives, which aim usually at developing the economy and promoting the image of the host destination. This essay sketches out the evolution of a sports events hosting strategy in a city that does not have the resources (either financial, human or in terms of infrastructures) to attract major international sports events. The challenges they have to face and a possible solution based on the event portfolio perspective are discussed through the article.
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In cancer patients treated for venous thromboembolism (VTE), including deep-vein thrombosis (DVT) and pulmonary embolism (PE), analyzing mortality associated with recurrent VTE or major bleeding is needed to determine the optimal duration of anticoagulation.This was a cohort study using the Registro Informatizado de Enfermedad TromboEmbólica (RIETE) Registry database to compare rates of fatal recurrent PE and fatal bleeding in cancer patients receiving anticoagulation for VTE.As of January 2013, 44,794 patients were enrolled in RIETE, of whom 7911 (18%) had active cancer. During the course of anticoagulant therapy (mean, 181 ± 210 days), 178 cancer patients (4.3%) developed recurrent PE (5.5 per 100 patient-years; 95% CI: 4.8-6.4), 194 (4.7%) had recurrent DVT (6.2 per 100 patient-years; 95% confidence interval [CI]: 5.3-7.1), and 367 (8.9%) bled (11.3 per 100 patient-years; 95% CI: 10.2-12.5). Of 4125 patients initially presenting with PE, 43 (1.0%) died of recurrent PE and 45 (1.1%) of bleeding; of 3786 patients with DVT, 19 (0.5%) died of PE, and 55 (1.3%) of bleeding. During the first 3 months of anticoagulation, there were 59 (1.4%) fatal PE recurrences and 77 (1.9%) fatal bleeds. Beyond the third month, there were 3 fatal PE recurrences and 23 fatal bleeds.In RIETE cancer patients, the rate of fatal recurrent PE or fatal bleeding was much higher within the first 3 months of anticoagulation therapy.
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Everyday tasks seldom involve isolate actions but sequences of them. We can see whether previous actions influence the current one by exploring the response time to controlled sequences of stimuli. Specifically, depending on the response-stimulus temporal interval (RSI), different mechanisms have been proposed to explain sequential effects in two-choice serial response tasks. Whereas an automatic facilitation mechanism is thought to produce a benefit for response repetitions at short RSIs, subjective expectancies are considered to replace the automatic facilitation at longer RSIs, producing a cost-benefit pattern: repetitions are faster after other repetitions but they are slower after alternations. However, there is not direct evidence showing the impact of subjective expectancies on sequential effects. By using a fixed sequence, the results of the reported experiment showed that the repetition effect was enhanced in participants who acquired complete knowledge of the order. Nevertheless, a similar cost-benefit pattern was observed in all participants and in all learning blocks. Therefore, results of the experiment suggest that sequential effects, including the cost-benefit pattern, are the consequence of automatic mechanisms which operate independently of (and simultaneously with) explicit knowledge of the sequence or other subjective expectancies.