Sliding gastric hiatal hernia diagnosis by transabdominal ultrasonography: An easy,reliable and non-invasive procedure

Objective. Data in the literature suggest the possibility of using ultrasonography to diagnose sliding gastric hiatal hernia. The aim of this study was to confirm the diagnostic accuracy of transabdominal ultrasonography for the diagnosis of sliding gastric hiatal hernia, using endoscopy as the reference test. The latter procedure was used since it also recognizes the presence of esophagitis and/or varices, two pathological conditions that could per se influence ultrasonographic evaluation, based on measurement of the esophageal diameter. Material and methods. A total of 180 consecutive patients, admitted to our hospital for endoscopy, were examined. Of these, 12 patients were not included in the final study. After fasting, the remaining 168 patients were first evaluated by ultrasonography and later by endoscopy. Esophageal diameter was measured by ultrasonography at the level of the diaphragmatic hiatus. Results. Using a diameter?≥?18 mm as the sensitivity threshold, 29 patients potentially affected by hiatal hernia were identified by ultrasonography. Upper endoscopy examination confirmed the presence of hiatal hernia in 24 of these patients and documented 4 additional hernias in the group of patients with a transdiaphragmatic esophageal diameter <18 mm (positive and negative predictive values were 82.7% and 97%, respectively). Analysis of the distribution of esophageal varices and esophagitis in all 168 excluded the possibility that these pathological conditions could influence the esophageal diameter. Conclusions. Ultrasonography represents a simple and well-tolerated diagnostic approach in sliding gastric hiatal hernia. The good diagnostic accuracy suggests its potential use in clinical and epidemiological settings.     

Robust sliding mode design for uncertain stochastic systems based on H∞ control method

In this paper, the design problem of sliding mode control (SMC) is addressed for uncertain stochastic systems modeled by Itô differential equations. There exist the parameter uncertainties in both the state and input matrices, as well as the unmatched external disturbance. The key feature of this work is the integration of SMC method with H_∞ technique such that the robust stochastic stability with a prescribed disturbance attenuation level γ can be achieved. A sufficient condition for the existence of the desired sliding mode controller is obtained via linear matrix inequalities. The reachability of the specified sliding surface is proven. Finally, a numerical simulation example is presented to illustrate the proposed method. Copyright © 2009 John Wiley & Sons, Ltd.     

Sliding ferroelectricity in 2D van der Waals materials: Related physics and future opportunities

Near the 100th anniversary of the discovery of ferroelectricity, so-called sliding ferroelectricity has been proposed and confirmed recently in a series of experiments that have stimulated remarkable interest. Such ferroelectricity exists widely and exists only in two-dimensional (2D) van der Waals stacked layers, where the vertical electric polarization is switched by in-plane interlayer sliding. Reciprocally, interlayer sliding and the “ripplocation” domain wall can be driven by an external vertical electric field. The unique combination of intralayer stiffness and interlayer slipperiness of 2D van der Waals layers greatly facilitates such switching while still maintaining environmental and mechanical robustness at ambient conditions. In this perspective, we discuss the progress and future opportunities in this behavior. The origin of such ferroelectricity as well as a general rule for judging its existence are summarized, where the vertical stacking sequence is crucial for its formation. This discovery broadens 2D ferroelectrics from very few material candidates to most of the known 2D materials. Their low switching barriers enable high-speed data writing with low energy cost. Related physics like Moiré ferroelectricity, the ferroelectric nonlinear anomalous Hall effect, and multiferroic coupling are discussed. For 2D valleytronics, nontrivial band topology and superconductivity, their possible couplings with sliding ferroelectricity via certain stacking or Moiré ferroelectricity also deserve interest. We provide critical reviews on the current challenges in this emerging area.     

动力髋螺钉内固定治疗股骨粗隆部骨折滑动钉切出16例原因分析

目的探讨运用动力髋固定股骨粗骨隆间骨折,切出股骨头的原因及预防措施。方法总结自1998~2004年应用动力髋内固定173例股骨粗隆间骨折的治疗经验,对16例动力髋螺钉切出失败病例进行分类及分析。结果173例病人获得随访。其中,16例发生切出股骨头颈(9.24%),分析失败病例,钉的位置显示钉位置于颈中者6例(37.5%),偏后者10例(62.5%)。结论未能解剖复位、滑动钉位置不良、尖顶距过大、骨质疏松及不当功能锻炼,是内固定失败的重要因素。     

Skin sliding closure technique is effective for management of infected prostheses in cases of arterial reconstruction with synthetic grafts

A clinical review of 400 prosthetic arterial reconstructions, carried out in the Second Department of Surgery of Kyushu University Hospital during a period from 1965 to 1981, revealed 10 graft infections (2.5 per cent). There were two out of 120 abdominal aneurysms (1.7 per cent) and 8 out of 260 aorto-femoral occlusive diseases (3.1 per cent). The contributing factors included intraoperative contamination with duodenal juice during surgery for abdominal aneurysms ruptured into the duodenum (2 cases), minor hematoma and/or lymphorrhoea at the groin or lower abdominal wall (5 cases), wound infection (1 case), compression necrosis of the sigmoid colon by the implanted graft (1 case) or perityphlitic abscess due to a perforating appendicitis (1 case). Bacteriologic examination revealed a predominance of a variety of staphylococcus at the groin or lower abdominal wall and E. coli in the abdominal cavity. Four patients expired. Limb amputation had to be done in 2, and 4 were cured. In the management of infected graft at the groin or lower abdominal wall, we used with success a skin sliding closure technique after continuous wound lavage in 3 patients.     

推力滑动轴承结构参数的数值研究

以推力轴承扇形瓦块为研究对象,采用柱面坐标,通过对二维雷诺方程进行离散化求解,得出推力滑动轴承的无量纲压力分布,并通过数值计算研究方法,详细研究了瓦高比、长宽比和瓦块数对轴承润滑性能的影响规律,指出了推力滑动轴承最佳结构参数的确定方法,为推力滑动轴承的结构设计提供了理论支撑。     

鼻咽癌动态和静态调强方式的剂量学比较

目的：探讨鼻咽癌动态调强方式（Sliding window）和静态调强方式（Step and shoot）2种调强方式的剂量学差异.方法：采用CADPLAN 6.4.7（helios） 治疗计划系统,对15例鼻咽癌需调强治疗的患者用Sliding window和Step and shoot 2种调强方式4种强度水平（Intensity Level）进行剂量学差异的比较.按强度水平分为SW、SSL10、SSL7、SSL5组.对4组的剂量学评估参数：PTV最大剂量（PTVDmax）、PTV平均剂量（PTVDmean）、PTV最小剂量（PTVDmin）、剂量体积直方图（DVH） 、适型指数（Conformity index,CI）、剂量不均匀性指数（Heterogeneity Index ,HI）、机器跳数（MU） 、子野数目（Segment）等数据进行评价.结果：（1）SW组PTV Dmax与SSL10、SSL7、SSL5组间比较差异有统计学意义（P＜0.05）,而SSL10、SSL7、SSL5组比较差异无统计学意义（P＞0.05）,随着强度水平的降低,最大剂量增高;（2）SW组MU与 SSL10、SSL7、SSL5组比较差异有统计学意义（P＜0.01）,而SSL10、SSL7、SSL5组间差异无统计学意义（P＞0.05）;（3）各组间Segment差异均有统计学意义（P＜0.01）;（4）各组间CI比较差异均无统计学意义（P＞0.05）;（5）各组间HI比较差异均无统计学意义（P＞0.05）.结论：鼻咽癌不同调强方式和强度水平的治疗计划均能为临床提供较满意的剂量学分布,Sliding window方式略优于不同强度水平的Step and shoot方式,但MU和Segment较多.     

Three-dimensional finite element analysis of the mechanical stress on root from orthodontic tooth movement by sliding mechanics

Summary In order to study mechanical stress on root from orthodontic tooth movement by sliding mechanics, a 3-dimensional finite element model incorporating all layers of a human mandibular dental arch with orthodontic appliance has been developed to simulate mechanical stress on root from the orthodontic tooth movement. Simulated orthodontic force of 2 N at 0, 30 and 45 degree from the horizontal axis was applied to the crown of the teeth. The finite element analysis showed when orthodontic forces were applied to the tooth, the stress was mainly concentrated at the neck of the tooth decreasing uniformly to the apex and crown. The highest stress on the root was 0.621 N/mm² for cervical margin of the canine, and 0.114 N/mm² for apical region of the canine. The top of canine crown showed the largest amount of displacement (2.417 μm), while the lowest amount of displacement was located at the apical region of canine (0.043 μm). In conclusion, this model might enable one to simulate orthodontic tooth movements clinically. Sliding force at 2 N is ideal to ensure the bodily orthodontic tooth movement. The highest stress concentration in the roots was always localized at the cervical margin when orthodontic force of 2 N at 0, 30 and 45 degree from the horizontal axis, so there may be the same risk of root resorption when orthodontic force of 2 N at 0, 30 and 45 degree was used in clinic cases.     

Tying a loop-to-strand suture: is it safe?

OBJECTIVE: This study was undertaken to evaluate the integrity of the loop-to-strand knot when tied with square and nonidentical sliding knots. STUDY DESIGN: The synthetic absorbable monofilament suture poliglecaprone 25 in 0 and 2-0 suture gauges was used in this experiment. For each suture gauge, 3 groups of knots were tested: (1) single strand-to-single strand, flat square knot, (2) loop-to-single strand, flat square knot, and (3) loop-to-single strand, nonidentical sliding knot. All knots were tied with 6 throws. The proportion of knots becoming untied was compared among the 3 groups for each suture gauge. Ultimate load required to untie or break knots within each group was also evaluated. RESULTS: The loop-to-strand knot performed well in both suture gauges tested as long as it was tied with a flat square knot. The loop-to-strand knot tied with a nonidentical sliding knot had an unacceptably high failure rate. CONCLUSION: The loop-to-strand termination of a continuous suture may be acceptable when tied with a 6-throw flat square knot but not acceptable if tied with sliding knots.