Modeling and simulation in supersonic three-temperature carbon dioxide turbulent channel flow

This paper pioneers the direct numerical simulation (DNS) and physical analysis in supersonic three-temperature carbon dioxide (CO2) turbulent channel flow. CO2 is a linear and symmetric triatomic molecular, with the thermal non-equilibrium three-temperature effects arising from the interactions among translational, rotational and vibrational modes under room temperature. Thus, the rotational and vibrational modes of CO2 are addressed. Thermal non-equilibrium effect of CO2 has been modeled in an extended three-temperature BGK-type model, with the calibrated translational, rotational and vibrational relaxation time. To solve the extended BGK-type equation accurately and robustly, non-equilibrium high-accuracy gas-kinetic scheme is proposed within the well-established two-stage fourth-order framework. Compared with the one-temperature supersonic turbulent channel flow, supersonic three-temperature CO2 turbulence enlarges the ensemble heat transfer of the wall by approximate 20%, and slightly decreases the ensemble frictional force. The ensemble density and temperature fields are greatly affected, and there is little change in Van Driest transformation of streamwise velocity. The thermal non-equilibrium three-temperature effects of CO2 also suppress the peak of normalized root-mean-square of density and temperature, normalized turbulent intensities and Reynolds stress. The vibrational modes of CO2 behave quite differently with rotational and translational modes. Compared with the vibrational temperature fields, the rotational temperature fields have the higher similarity with translational temperature fields, especially in temperature amplitude. Current thermal non-equilibrium models, high-accuracy DNS and physical analysis in supersonic CO2 turbulent flow can act as the benchmark for the long-term applicability of compressible CO2 turbulence.Comment: Carbon dioxide flow, Vibrational modes, Three-temperature effects, Supersonic turbulent channel flow

Off-hour admission and mortality risk for 28 specific diseases: A systematic review and meta-analysis of 251 cohorts

Background: A considerable amount of studies have examined the relationship between off-hours (weekends and nights) admission and mortality risk for various diseases, but the results remain equivocal. Methods and Results: Through a search of EMBASE, PUBMED, Web of Science, and Cochrane Database of Systematic Reviews, we identified cohort studies that evaluated the association between off-hour admission and mortality risk for disease. In a random effects meta-analysis of 140 identified articles (251 cohorts), off-hour admission was strongly associated with increased mortality for aortic aneurysm (odds ratio [OR], 1.52; 95% confidence interval, 1.30-1.77), breast cancer (1.50, 1.21-1.86), leukemia (1.45, 1.17-1.79), respiratory neoplasm (1.32, 1.20-1.26), pancreatic cancer (1.32, 1.12-1.56), malignant neoplasm of genitourinary organs (1.27, 1.08-1.49), colorectal cancer (1.26, 1.07-1.49), pulmonary embolism (1.20, 1.13-1.28), arrhythmia and cardiac arrest (1.19, 1.09-1.29), and lymphoma (1.19, 1.06-1.34). Weaker (OR<1.19) but statistically significant association was noted for renal failure, traumatic brain injury, heart failure, intracerebral hemorrhage, subarachnoid hemorrhage, stroke, gastrointestinal bleeding, myocardial infarction, chronic obstructive pulmonary disease, and bloodstream infections. No association was found for hip fracture, pneumonia, intestinal obstruction, aspiration pneumonia, peptic ulcer, trauma, diverticulitis, and neonatal mortality. Overall, Off-hour admission was associated with increased mortality for 28 diseases combined (OR, 1.11; 95% confidence interval, 1.10-1.13).Conclusions: Off-hour admission is associated with increased mortality risk, and the associations varied substantially for different diseases. Specialists, nurses, as well as hospital administrators and health policy makers can take these findings into consideration to improve the quality and continuity of medical services

Optimizing LLM Queries in Relational Workloads

Analytical database providers (e.g., Redshift, Databricks, BigQuery) have rapidly added support for invoking Large Language Models (LLMs) through native user-defined functions (UDFs) to help users perform natural language tasks, such as classification, entity extraction, and translation, inside analytical workloads. For instance, an analyst might want to extract customer sentiments on millions of product reviews. However, LLM inference is highly expensive in both computational and economic terms: for example, an NVIDIA L4 GPU running Llama2-7B can only process 6 KB of text per second. In this paper, we explore how to optimize LLM inference for analytical workloads that invoke LLMs within relational queries. We show that relational queries present novel opportunities for accelerating LLM inference, including reordering rows to maximize key-value (KV) cache reuse within the LLM inference engine, reordering columns within a row to further increase cache reuse, and deduplicating redundant inference requests. We implement these optimizations in Apache Spark, with vLLM as the model serving backend and achieve up to 4.4x improvement in end-to-end latency on a benchmark of diverse LLM-based queries on real datasets. To the best of our knowledge, this is the first work to explicitly address the problem of optimizing LLM invocations within SQL queries

Association between exposure to noise and risk of hypertension: A meta-analysis of observational epidemiological studies

Background and Objective: An increasing amount of original studies suggested that exposure to noise could be associated with the risk of hypertension, but the results remain inconsistent and inconclusive. We aimed to synthesize available epidemiological evidence about the relationship between various types of noise and hypertension, and to explore the potential dose-response relationship between them in an up-to-date meta-analysis. Methods: We conducted a literature search of PubMed and Embase from these databases’ inception through December 2016 to identify observational epidemiological studies examining the association between noise and risk of hypertension. A Random-effects model was used to combine the results of included studies. Dose-response meta-analysis was conducted to examine the potential dose-response relationship. Results: Thirty-two studies (five cohort studies, one case-control study, and twenty-six cross-section Studies) involving 264,678 participants were eligible for inclusion. Pooled result showed that living or working in environment with noise exposure was significantly associated with increase risk of hypertension (OR 1.62; 95% CI: 1.40 to 1.88). We found no evidence of a curve linear association between noise and risk of hypertension. Dose-response analysis suggested that, for an increment of per 10 dB(A) of noise, the combined odds ratio of hypertension was 1.06 (95% CI: 1.04 to 1.08). Conclusions: Integrated epidemiological evidence supports the hypothesis that exposure to noise may be a risk factor of hypertension, and there is a positive dose-response association between them

Meta-analysis on the association between the frequency of tooth brushing and diabetes mellitus risk

BACKGROUND AND OBJECTIVE: Epidemiological studies suggested that the frequency of tooth brushing might be associated with the risk of diabetes mellitus (DM), but the results were inconsistent and no systematic review was conducted to focus on this topic. In this meta-analysis, we synthesized available observational epidemiological evidences to identify the association between tooth brushing and DM risk and investigate the potential dose-response relationship of them. METHODS: We searched PubMed and Embase from their inception through December 2017 to identify observational studies examining the association between tooth brushing and the risk of DM. Reference lists from retrieved articles were also reviewed. We quantitatively combined results of the included studies using a random-effects model. Dose-response meta-analysis was conducted to further examine the effect of tooth brushing frequency on DM risk. RESULTS: We identified 20 relevant studies (one cohort study, 14 case-control studies, and five cross-sectional studies) involving161,189 participants and 10,884 patients with DM. Compared with the highest tooth brushing frequency, the lowest level was significantly associated with an increased risk of DM (OR 1.32, 95% CI: 1.19 to 1.47), and there was no significant heterogeneity across the included studies (P = 0.119, I2 = 28.1%). Exclusion of any single study did not materially alter the combined risk estimate. The dose-response analysis indicated that the summary odds of DM for an increment of one time of tooth brushing per day was 1.20 (95% CI: 1.16-1.24). CONCLUSIONS: Integrated epidemiological evidence supports the hypothesis that low frequency of tooth brushing may be a risk factor of DM, and lower frequencies of tooth brushing were significantly associated with higher risk of DM

Reporting quality and statistical analysis of published dose-response meta-analyses was suboptimal: A cross-sectional literature survey

Objective To investigate the characteristics, methodological quality, and reporting of statistical analyses of published dose-response meta-analyses (DRMAs). Study Design and Setting We searched PubMed to identify DRMAs published in 2017. The reporting characteristics and methodological qualities were assessed by the PRISMA (27 items) and AMSTAR (11 items) respectively. We also summarized the reporting of statistical analyses of included DRMAs. Results We identified 93 DRMAs, most of which (59/93) were conducted by Chinese researchers, the main outcome was the incidence of cancers. Of the PRISMA and AMSTAR items, twenty and five were well complied (80% or more) respectively. The compliance rates of several PRISMA checklist items, such as structured summary, objectives, protocol and registration, and funding, were less than 50%. There were no criteria to estimate the doses for the open-ended intervals of exposure or intervention doses. When the restricted cubic splines were used to fit nonlinear dose-response relationships, there were also no criteria to determine the fixed knots. Conclusion The adherence to the methodological items of reporting guidelines and statistical analysis of published DRMAs were suboptimal. Development of reporting guidelines to assist authors in writing and readers in critically appraising the reports of DRMAs is timely

Prevalence of metabolic syndrome among middle-aged and elderly adults in China: current status and temporal trends

Background: Metabolic syndrome (MetS) is a cluster of major risk factors for cardiovascular diseases. We aimed to estimate prevalence and distribution of MetS among middle-aged and elderly adults in China. Methods: The present analysis used data from a national study in 2014–2015. We defined MetS by different definitions, and compared results of the present study and previous nationally representative studies to illustrate possible temporal changes in MetS prevalence. Results: The estimated prevalence of MetS was 18.4% by the ATP III criteria, 34.0% by the revised ATP III criteria, and 26.9% by IDF criteria. The prevalence was higher in women, older adults, those with lower education level, and in economically developed regions. Contrasting with previous national studies, adults in urban areas had a lower rate of MetS than those in rural areas (odds ratio 0.94; 95% CI 0.92−0.97). Rural adults had worse deterioration or less improvement in abdominal obesity, overweight, hypertension, and high fasting plasma glucose, than urban adults, which was particularly striking for women. Conclusion: While measures to prevent and control cardiovascular diseases need to be strengthened in China, rapid increasing risk factors among rural residents and women should be prioritized in making public health policy decisions

Carotid Atherosclerosis Detected by Ultrasonography: A National Cross‐Sectional Study

Background: Carotid atherosclerosis (CA) is a reflector of generalized atherosclerosis that is associated with systemic vascular disease. Data are limited on the epidemiology of carotid lesions in a large, nationally representative population sample. We aimed to evaluate the prevalence of CA detected by carotid ultrasonography and related risk factors based on a national survey in China. Methods and Results: A total of 107 095 residents aged ≥40 years from the China National Stroke Prevention Project underwent carotid ultrasound examination. Participants with carotid endarterectomy or carotid stenting and those with stroke or coronary heart disease were excluded. Data from 84 880 participants were included in the analysis. CA was defined as increased intima–media thickness (IMT) ≥1 mm or presence of plaques. Of the 84 880 participants, 46.4% were men, and the mean age was 60.7±10.3 years. The standardized prevalence of CA was 36.2% overall, increased with age, and was higher in men than in women. Prevalence of CA was higher among participants living in rural areas than in urban areas. Approximately 26.5% of participants had increased IMT, and 13.9% presented plaques. There was an age‐related increase in participants with increased IMT, plaque presence, and stenosis. In multiple logistic regression analysis, older age, male sex, residence in rural areas, smoking, alcohol consumption, physical inactivity, obesity, hypertension, diabetes mellitus, and dyslipidemia were associated with CA. Conclusions: CA was highly prevalent in a middle‐aged and older Chinese population. This result shows the potential clinical importance of focusing on primary prevention of atherosclerosis progression