Convergence Rate Analysis for Deep Ritz Method

Using deep neural networks to solve PDEs has attracted a lot of attentions recently. However, why the deep learning method works is falling far behind its empirical success. In this paper, we provide a rigorous numerical analysis on deep Ritz method (DRM) [47] for second order elliptic equations with Neumann boundary conditions. We establish the first nonasymptotic convergence rate in $H^1$ norm for DRM using deep networks with ${\rm ReLU}^2$ activation functions. In addition to providing a theoretical justification of DRM, our study also shed light on how to set the hyperparameter of depth and width to achieve the desired convergence rate in terms of number of training samples. Technically, we derive bound on the approximation error of deep ${\rm ReLU}^2$ network in $C^1$ norm and bound on the Rademacher complexity of the non-Lipschitz composition of gradient norm and ${\rm ReLU}^2$ network, both of which are of independent interest.     

火针治疗非哺乳期乳腺炎评介

火针疗法是一种独特的中医传统外治方法,具有以针代刀提脓泻毒等多种功效。非哺乳期乳腺炎是一种常见的难治性乳腺良性疾病,其病情复杂多变,易形成脓肿和窦道、瘘管,迁移难愈,适合火针治疗,但相关研究较少。在总结古今医家运用火针治疗非哺乳期乳腺炎临床经验的基础上,对火针治疗非哺乳期乳腺炎的适应证、禁忌证、操作方法及注意事项进行了规范。     

The applicability of Willems' method for age estimation in southern Turkish children: A preliminary study

The aims of the present study were to evaluate the applicability and accuracy of Willems' method for assessing southern Turkish children and to analyze the practicability of this method in different age groups for both genders.Panoramic radiographs of 756 children (378 females, 378 males) aged between 5 and 14.99 years were examined by one observer. This retrospective study involved a contemporary southern Turkish population. The chronological ages of the subjects were divided into 10 groups. These 10 groups consisted of children of the following ages 5 and 14.99. Relationships between continuous variables were examined using Pearson's correlation coefficient. The paired t-test was used to compare all data according to gender and age groups. A p-value of less than 0.05 was considered significant for all statistical data.According to the results, a very high correlation was found for both girls (r² = 0.946) and for boys (r² = 0.940). Dental age (DA) and chronological age (CA) were consistent for girls in the four age groups (5–5.99, 6–6.99, 12–12.99, and 14–14.99) and for boys in the three age groups (5–5.99,13–13.99, 14–14.99).The maturity score of Willems' Belgian samples of the DA was applicable to seven groups of the southern Turkish children. The present study reports that Willems' method is more accurate for girls than for boys.     

A quantitative comparison analysis of diatoms in the lung tissues and the drowning medium as an indicator of drowning

The presence of diatoms in the lung tissues, internal organs and bone marrow is considered as the supportive evidence in the diagnosis of death by drowning. Generally, the diatoms detected in the lung tissues are regarded as insignificant since these diatoms can be detected in the lung tissues of the postmortem immersion bodies. In this study, we analyzed the relationships between the numbers of the diatoms in the lung tissues and the drowning medium. We made a comparison analysis between the diatoms in the lung tissues and the drowning medium using the ratio of diatom numbers in both samples (L/D ratio), utilizing Microwave Digestion - Vacuum Filtration - Automated Scanning Electron Microscopy method. Our data indicate that the L/D ratios in victims of the drowning group were higher than the postmortem immersion group. A higher L/D ratio provides valuable information about the cause of death in drowning victims. Quantitative diatom analysis in the lung tissues, especially combined with the diatom analysis of the drowning medium, provides supportive evidence in determining if a body recovered in water was due to drowning or not.     

Experimental and Numerical Investigation of an Axial Rotary Blood Pump

Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near‐wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds‐averaged Navier–Stokes simulations‐computational fluid dynamics (URANS‐CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall‐particle image velocimetry technique, and the visualization of near‐wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS‐CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal.     

飞行员头盔质量特性测量设备和方法

目的研制一套飞行员头盔质量特性测量设备,满足飞行员头盔加装显示器、夜视镜以及头盔上配挂供氧面罩时质量特性的精确测量,为飞行头盔的设计、使用、评价提供试验条件和方法。方法根据飞行头盔的功能拓展,采用标准头模和两面垂直的开放式框架,按照静力平衡的原理设计三支点平衡的头盔质量和重心测量平台,按照扭摆原理设计头盔转动惯量测量的磁悬浮扭摆装置;研究制订头盔质量、重心和转动惯量的测量方法。结果研制了一套飞行员头盔质量、重心和转动惯量测量系统,建立了用于头盔重心和转动惯量测量的坐标体系,测量系统精度高,量程大,操作简便。结论飞行员头盔质量、重心和转动惯量测量系统设计科学、构造合理、使用可靠,可满足常规飞行保护头盔、加装显示器和夜视镜的飞行头盔、配挂供氧面罩飞行头盔质量特性的精确测量。     

顶舌法联合刮舌法对舌系带过短患儿术后舌尖音训练效果的分析

目的：探讨顶舌法联合刮舌法对舌系带过短患儿术后舌尖音训练效果的影响。方法采用随机对照研究设计,将50例舌系带过短术后仅有舌尖音发音障碍的患儿（4～8岁）随机分为实验组25例,对照组25例。实验组在常规语音训练的基础上配合顶舌刮舌法训练,对照组采用常规语音训练,分别测试两组患儿在语音治疗前和治疗3个疗程后的语音清晰度,比较两组结果。结果实验组及对照组患儿治疗前的语音清晰度分别约为37．91％、37．69％,治疗后分别为87．69％、72．99％,两组患儿治疗前语音清晰度差异无统计学意义（t＝0．726,P ＞0．05）,治疗后两组患儿语音清晰度均较治疗前明显提高,差异有统计学意义（P ＜0．001）,且实验组患儿语音清晰度显著高于对照组。结论顶舌法联合刮舌法可以促进舌系带过短患儿术后仅有舌尖音发音障碍患儿语音清晰度的提高。     

掌侧与背侧手法复位石膏固定治疗Colles骨折的疗效分析

目的探讨掌侧与背侧手法复位石膏固定治疗Colles骨折的临床疗效。方法回顾性分析自2012-06—2015-05采用手法复位石膏固定治疗的142例Colles骨折,72例采用掌侧复位方法治疗(观察组),70例采用背侧复位方法治疗(对照组)。比较2组一次性复位上位率,复位上位时和复位后4周掌倾角、尺偏角、桡骨茎突高度,骨折愈合时间,末次随访Gartland-Werley腕关节功能评分。结果观察组一次性上位70例,一次性上位率97.2%;对照组一次性上位58例,一次性上位率82.9%;观察组一次性上位率优于对照组,差异有统计学意义(χ~2=8.241,P=0.004)。复位上位后X线片显示2组掌倾角、尺偏角、桡骨茎突高度比较差异无统计学意义(P0.05)。复位后4周随访X线片显示对照组掌倾角、桡骨茎突高度较观察组丢失更大,差异有统计学意义(P0.05);对照组尺偏角丢失大于观察组,但差异无统计学意义(P0.05)。观察组腕关节功能评分优良率明显高于对照组,差异有统计学意义(χ~2=3.877,P=0.049)。结论掌侧手法复位治疗Colles骨折优于背侧手法复位,一次性复位上位率高,桡骨短缩及角度丢失更小,腕关节功能恢复好,患者满意度高。     

276例皮试仪皮试法阳性反应结果判断与影响因素分析

目的探讨皮试仪皮试法阳性反应的结果判断与影响因素。方法对276例皮试仪法皮试阳性患者以皮内注射法进行复测,验证皮试仪皮试法的准确性,并分析假阳性结果的原因。结果 276例阳性反应患者中,非典型阳性反应72例,占26.09%;患者复测后阳性200例,假阳性76例,患者用药后均无药物反应。不同性别、年龄段、最近3d有无连续使用同种类抗生素、有无同类药物过敏史的患者假阳性率比较,差异有统计学意义(均P0.01);不同药物种类、其他过敏史、家族过敏史比较,差异无统计学意义(均P0.05)。结论皮试仪说明书上的阳性结果判断标准有待于进一步修正和完善;临床需严格按照操作规程皮试,并重点观察婴幼儿、妇女及未使用过同类抗生素人群,积极预防过敏反应。     

基于文献的我国脑梗死中医护理研究现状分析

目的了解和分析我国脑梗死中医护理研究现状,为中医护理临床及研究提供参考。方法从4个中文数据库中检索建库至2016年3月脑梗死中医护理文献,采用计量分析及关键词共词矩阵分析法进行文献特征分析。结果共检出脑梗死中医护理文献5 441篇(硕博士论文681篇,会议论文90篇,期刊论文4 670篇;1963~1994年1~10篇,1995~2004年15~86篇,2005~2015年102~965篇),4 670篇论文分布在484种期刊,其中475篇(10.17%)发表在27种护理期刊;446篇(8.20%)有基金支持;有核心作者318人,平均发文6篇;研究机构共2 572个,排序前10的均为中医药院校及其附属医院;研究内容主要包括心理干预,肢体、神经、运动及认知康复护理,康复期症状护理,并发症及合并疾病护理,急性期溶栓护理5个方面。结论我国脑梗死中医护理研究经历了缓慢发展期,现处于兴盛时期,研究数量已成规模但质量偏低,研究内容覆盖全面但欠深入细化,载文期刊分布广泛但护理期刊载文偏少,应加以改进,以提升脑梗死中医护理研究质量。