LES modelling of flow in a simple airway model

Detailed information about the flow field pattern is highly important in accurately predicting particle deposition sites in the human airway. Flow in the upper airway during heavy breathing can have a Reynolds number as high as 9300, and therefore presents turbulent features. Although turbulence is believed to have an important effect on the airflow and other transport processes in the bronchial tree, to date both theoretical and numerical studies have predominantly assumed the flow to be laminar. In this paper, transitional/turbulent flow during inspiration is studied using a large eddy simulation (LES) in a single asymmetric bifurcation model of human upper airway. The influence of the non-laminar flow on the patterns and the particle paths is investigated in both 2D and 3D models. Throughout the investigation, comparisons with the laminar and conventional k- models for the same configuration and flow conditions are made. The LES model is also carefully validated against published experimental data in a stenotic tube model. The results demonstrate that the LES model is capable of capturing instantaneous eddy formation and flow separation in (almost) laminar, transitional and turbulent flow regimes, and hence may be used as a powerful and practical tool to provide much of the detailed flow information required for tracing the particle trajectories and particle deposition in human airways.     

Laser doppler imaging of menstrual symptoms

In this paper, the skin blood flow for the stomach and forehead regions of 36 female patients with menstrual symptoms was studied using a moorLDI laser Doppler imager in which the results of 6 typical patients are included. The patterns obtained at the two sites are common to all women in the sample who have menstrual symptoms. Cold stress testing was also investigated to see if it was effective in bringing out any skin blood flow fluctuation at these regions caused by menstrual symptoms. Each patient attended two scanning sessions: one before and the other during menstruation. During each session, the patient was scanned three consecutive times, each on the stomach and the forehead skin regions. For each region, the first measurement was a bare scanning whereas for the second and the third, 85% denatured ethanol (cold stress test) was applied onto the required scan areas. It was found that cold stress testing was able to bring out distinct differences in LDI perfusion images before and during menstruation. Results were best captured when perfusion images were taken approximately after 85% denatured ethanol had been applied in two layers for 30 s, allowed to evaporate over the next 5 min (approximately the time taken to obtain one image), reapplied for another 30 s and then finally over the next 30 s allowed to evaporate further. However, it was impossible to deduce conclusively any correlation regarding migraine and skin blood flow since all the patients for this work had menstrual cramps only.     

A survey of technical considerations in the construction of intestinal stomas

Reported complications rates for the construction of intestinal stomas are high. Many of these complications result from improper construction, improper location, or other technical errors. In order to sample the techniques of stoma construction currently in use, a survey was conducted at the 69th Annual Clinical Congress of the American College of Surgeons in Atlanta in conjunction with our scientific exhibit "Complications of Intestinal Stomas." A total of 245 surgeons completed the questionnaire with a mean age of 47.8 years. The routine use of fascial-seromuscular tacking sutures and primary maturation of a loop colostomy in the presence of distal obstruction were among the most controversial technical points considered. Many other subtle but important principles of stoma construction were also discussed. In addition, the authors contend that many of the techniques currently in use result from an underemphasis on the importance of proper stoma construction in many surgical training programs.     

Assessing the Impact of Salt Reduction Initiatives on the Chronic Disease Burden of Singapore

Globally, many countries are facing an increasing burden of chronic disease due to ageing populations, of which cardiovascular disease forms a large proportion. Excess dietary sodium contributes to cardiovascular disease risk and requires intervention at a population level. This study aimed to quantify the impact of several salt reduction initiatives on population health over a 30-year horizon using GeoDEMOS, a population model from Singapore. Four interventions were modelled in four demographic groups in 2020 for a total of 16 intervention scenarios. The effect of 0.5, 2.0, and 4.0 g/day reductions in daily salt consumption, along with adherence to the World Health Organization guidelines of a maximum of 5.0 g of salt each day, was modelled in the entire population, including the overweight and obese, the elderly, and diabetics. In each scenario, the number of averted incident cases of acute myocardial infarction and stroke, along with the disability-adjusted life years up to 2050, was monitored. We found 4.0 g/day reductions in salt consumption were the most effective when implemented across the entire population, resulting in 24,000 averted incident cases of cardiovascular disease and 215,000 disability-adjusted life years over 30 years. This is a large figure when compared with the 29,200 projected annual incident cases of cardiovascular disease in 2050. When targeted at specific high-risk demographic groups, the largest effects were observed in the overweight and obese, with the same intervention yielding 10,500 averted incident cases of cardiovascular disease and 91,500 disability-adjusted life years. Quantifying the benefits of salt reduction initiatives revealed a significant impact when administered across the entire population or the overweight and obese. Health promotion efforts directed toward sustainably reducing salt consumption will help to lower the chronic disease burden on the healthcare system in years to come.     

Promotion of knowledge transfer and retention in year 2 medical students using an online training exercise

Advances in Health Sciences Education - It was recently shown that novice medical students could be trained to demonstrate the speed-to-diagnosis and diagnostic accuracy typical of System-1-type...     

远视性屈光不正儿童屈光状态远期变化

目的探讨远视性屈光不正儿童屈光状态远期变化规律.方法对162例(324只眼)3～12岁远视性屈光不正儿童进行5～12.5年的观察,分别按性别、眼别、子午线、远视程度及不同年龄阶段进行分级,计算各组的年均下降远视屈光度,用u检验和方差分析.结果男女两组年均下降屈光度分别为0.34±0.17D和0.35±0.17D,左右眼为0.35±0.L7D、0.33±0.16D,平均90°和180°子午线轴为0.35±0.L6D、0.36±0.17D,无显著性差异;轻、中、高度远视为0.45±0.19D、0.27±0.16D、0.36±0.17D,中度远视下降最慢,轻、高度远视差异无显著性;＜6岁,6～9岁和≥9岁三组分别为0.46±0.15、0.37±020D、0.15±0.06D,有显著性差异.结论远视性屈光不正儿童的屈光随年龄的增长逐年下降,9岁以后趋于稳定,但散光无明显改变;远视下降速度以中度远视最慢,高度和轻度远视下降较快,后者易发展为近视眼.下降速度与性别、眼别无关.     

Risk Factors and Effect of Acute Kidney Injury on Outcomes Following Total Hip and Knee Arthroplasty

BackgroundDevelopment of acute kidney injury (AKI) following primary total joint arthroplasty (TJA) is a potentially avoidable complication associated with negative outcomes including discharge to facilities and mortality. Few studies have identified modifiable risk factors or strategies that the surgeon may use to reduce this risk.MethodsWe identified all patients undergoing primary TJA at a single hospital from 2005 to 2017, and collected patient demographics, comorbidities, short-term outcomes, as well as perioperative laboratory results. We defined AKI as an increase in creatinine levels by 50% or 0.3 points. We compared demographics, comorbidities, and outcomes between patients who developed AKI and those who did not. Multivariate regressions identified the independent effect of AKI on outcomes. A stochastic gradient boosting model was constructed to predict AKI.ResultsIn total, 814 (3.9%) of 20,800 patients developed AKI. AKI independently increased length of stay by 0.26 days (95% confidence interval [CI] 0.14-0.38, P < .001), in-hospital complication risk (odds ratio = 1.73, 95% CI 1.45-2.07, P < .001), and discharge to facility risk (odds ratio = 1.26, 95% CI 1.05-1.53, P = .012). Forty-one predictive variables were included in the predictive model, with important potentially modifiable variables including body mass index, perioperative hemoglobin levels, surgery duration, and operative fluids administered. The final predictive model demonstrated excellent performance with a c-statistic of 0.967.ConclusionOur results confirm that AKI has adverse effects on outcome metrics including length of stay, discharge, and complications. Although many risk factors are nonmodifiable, maintaining adequate renal perfusion through optimizing preoperative hemoglobin, sufficient fluid resuscitation, and reducing blood loss, such as through the use of tranexamic acid, may aid in mitigating this risk.