A macro-element based practical model for seismic analysis of steel-concrete composite high-rise buildings

This is the post-print version of the final paper published in Engineering Structures. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.Seismic behaviour of steel–concrete composite high-rise buildings, composed of external steel frames (SFs) and internal concrete tube (CT), with rectangular plan is investigated in this paper. A macro-element based model is established for seismic analysis of composite high-rise buildings aiming at predicting their global responses under earthquakes. By employing this macro-element based model, natural frequencies and vibration modes, storey and inter-storey drifts, overturning moments and storey shear forces of composite structures, induced by earthquakes, are able to be obtained with much less computation time and cost compared with using micro-element based analytical models. To validate its efficiency and reliability, the macro-element based model is employed to analyse a 1/20 scaled-down model of a 25-storey steel–concrete composite high-rise building subjected to simulated earthquakes with various intensities through a shaking table. Natural frequencies and storey drifts of the model structure are obtained from numerical analyses and compared with those from shaking table test results. It has been found that the calculated dynamic responses of the composite model structure subjected to minor, basic, major and super strong earthquakes agree reasonably well with those obtained from experiments, suggesting that the proposed macro-element based model is appropriate for inelastic time-history analyse for global responses of steel–concrete composite high-rise structures subjected to earthquakes with satisfactory precision and reliability. This research thus provides a practical model for elastic and inelastic deformation check of high-rise composite buildings under earthquakes.Ministry of Science and Technology of Chin

Prediction of uncomplicated pregnancies in obese women: A prospective multicentre study

BACKGROUND: All obese pregnant women are considered at equal high risk with respect to complications in pregnancy and birth, and are commonly managed through resource-intensive care pathways. However, the identification of maternal characteristics associated with normal pregnancy outcomes could assist in the management of these pregnancies. The present study aims to identify the factors associated with uncomplicated pregnancy and birth in obese women, and to assess their predictive performance. METHODS: Data form obese women (BMI ≥ 30 kg/m 2 ) with singleton pregnancies included in the UPBEAT trial were used in this analysis. Multivariable logistic regression was used to identify sociodemographic, clinical and biochemical factors at 15 +0 to 18 +6 weeks' gestation associated with uncomplicated pregnancy and birth, defined as delivery of a term live-born infant without antenatal or labour complications. Predictive performance was assessed using area under the receiver operating characteristic curve (AUROC). Internal validation and calibration were also performed. Women were divided into fifths of risk and pregnancy outcomes were compared between groups. Sensitivity, specificity, and positive and negative predictive values were calculated using the upper fifth as the positive screening group. RESULTS: Amongst 1409 participants (BMI 36.4, SD 4.8 kg/m 2 ), the prevalence of uncomplicated pregnancy and birth was 36% (505/1409). Multiparity and increased plasma adiponectin, maternal age, systolic blood pressure and HbA1c were independently associated with uncomplicated pregnancy and birth. These factors achieved an AUROC of 0.72 (0.68-0.76) and the model was well calibrated. Prevalence of gestational diabetes, preeclampsia and other hypertensive disorders, preterm birth, and postpartum haemorrhage decreased whereas spontaneous vaginal delivery increased across the fifths of increasing predicted risk of uncomplicated pregnancy and birth. Sensitivity, specificity, and positive and negative predictive values were 38%, 89%, 63% and 74%, respectively. A simpler model including clinical factors only (no biomarkers) achieved an AUROC of 0.68 (0.65-0.71), with sensitivity, specificity, and positive and negative predictive values of 31%, 86%, 56% and 69%, respectively. CONCLUSION: Clinical factors and biomarkers can be used to help stratify pregnancy and delivery risk amongst obese pregnant women. Further studies are needed to explore alternative pathways of care for obese women demonstrating different risk profiles for uncomplicated pregnancy and birth

Time course, predictors and clinical implications of stent thrombosis following primary angioplasty. Insights from the DESERT cooperation

Item does not contain fulltextPrimary percutaneous coronary intervention (pPCI) has improved survival as compared to thrombolysis. Concerns still remain regarding the risk of stent thrombosis in the setting of STEMI, especially after drug-eluting stent (DES) implantation. Therefore, the aim of this study was to report on the timing of stent thrombosis (ST) with both DES and bare metal stents (BMS) and its prognostic significance in patients undergoing pPCI. The Drug-Eluting Stent in Primary Angioplasty (DESERT) cooperation is based on a pooled database including individual data of randomised trials that evaluate the long-term safety and effectiveness of DES as compared to BMS in patients undergoing pPCI for STEMI. Follow-up data were collected for 3-6 years after the procedure. ST was defined as definite or probable, based on the ARC definition. The study population consists of 6,274 STEMI patients undergoing primary angioplasty with BMS or DES. At 1201 +/- 440 days, ST occurred in 267 patients (4.25%). Most of the events were acute or subacute (within 30 days) and very late (> 1 years), with different distribution between DES vs BMS. Patients with ST were more often diabetic (21.7% vs 15.1%, p=0.005), more frequently had post-procedural TIMI 0-2 flow (14.0% vs 9.3%, p = 0.01), and were less often treated with dual antiplatelet therapy at one year follow-up. Diabetes (p = 0.036), post-procedural TIMI 0-2 Flow (p = 0.013) and ischaemia time > 6 hours (p = 0.03) were independent predictors of ST. Post-procedural TIMI 0-2 flow (p = 0.001) and ischaemia time > 6 hours (p 6 hours (p = 0.05) was independent predictor of late ST, whereas diabetes (p = 0.022) and use of DES (p = 0.002) were independent predictors of very late ST. ST was associated with a significantly higher mortality (23.6% vs 6%, p < 0.001). The greatest impact on mortality was observed with subacute (40.4%) and late (20.9%) ST, as compared to acute (12.5%) and very late (9.1%) ST. ST was an independent predictor of mortality (HR [95%CI] = 3.73 [2.75-5.07], p < 0.001). In conclusion, ST occurs relatively frequently also beyond the first year for up to six years after pPCI in STEMI, with higher late occurrence rates among patients treated with first generation DES. ST after pPCI is a powerful predictor of mortality, especially subacute ST

Meta-analysis comparing efficacy and safety of first generation drug-eluting stents to bare-metal stents in patients with diabetes mellitus undergoing primary percutaneous coronary intervention

Item does not contain fulltextSeveral concerns have emerged regarding the higher risk for stent thrombosis (ST) after drug-eluting stent (DES) implantation, especially in the setting of ST-segment elevation myocardial infarction (STEMI). Few data have been reported so far in patients with diabetes mellitus, which is associated with high rates of target vessel revascularization after bare-metal stent (BMS) implantation but also higher rates of ST after DES implantation. Therefore, the aim of this study was to perform a meta-analysis of individual patients' data to evaluate the long-term safety and effectiveness of DES compared with BMS in patients with diabetes who undergo primary percutaneous coronary intervention for STEMI. Published reports were scanned by formal searches of electronic databases (MEDLINE and CENTRAL). All completed randomized trials of DES for STEMI were examined. No language restrictions were enforced. Individual patients' data were obtained from 11 of 13 trials, including a total of 972 patients with diabetes (616 [63.4%] randomized to DES and 356 [36.6%] to BMS). At long-term follow-up (median 1,095 days, interquartile range 1,087 to 1,460), DES significantly reduced the occurrence of target vessel revascularization (hazard ratio 0.42, 95% confidence interval 0.29 to 0.59, p 1 year) with DES. In conclusion, this meta-analysis, based on individual patients' data from 11 randomized trials, showed that among patients with diabetes with STEMIs who undergo primary percutaneous coronary intervention, sirolimus-eluting stents and paclitaxel-eluting stents, compared with BMS, are associated with a significant reduction in target vessel revascularization at long-term follow-up, without any apparent concern in terms of mortality, despite the trend toward higher rates of reinfarction and ST

Adoption and correlates of Postgraduate Hospital Educational Environment Measure (PHEEM) in the evaluation of learning environments – A systematic review^*

<p><b>Background:</b> The Postgraduate Hospital Educational Environment Measure (PHEEM) is a highly reliable and valid instrument to measure the educational environment during post graduate medical training. This review extends earlier reports by evaluating the extant adoption of PHEEM in various international clinical training sites, and its significant correlations in order to expand our understanding on the use of PHEEM and facilitate future applications and research.</p> <p><b>Method:</b> A systematic literature review was conducted on all articles between 2005 and October 2015 that adopted and reported data using the PHEEM.</p> <p><b>Results:</b> Overall 30 studies were included, encompassing data from 14 countries internationally. Notable differences in the PHEEM scores were found between different levels of training, disciplines, and clinical training sites. Common strengths and weaknesses in learning environments were observed and there were significant correlations between PHEEM scores and In-Training Exam (ITE) performance (positive correlation) and level of burnout (negative correlation), respectively.</p> <p><b>Conclusions:</b> PHEEM is widely adopted in different learning settings, and is a useful tool to identify the strengths and weaknesses of an educational environment. Future research can examine other correlates of PHEEM and longitudinal changes in interventional studies.</p