纵向压力对受压弯曲构件沿斜截面强度的影响

研究证明,纵向压力对构件沿斜截面的强度有很大影响。当纵向压力作用于截面中心时,则对受横向力作用的构件强度起积极作用;当纵向压力作用线偏离中心时,则使构件沿斜截面强度受到影响。显然,这不仅取决于纵向压力,而且还与相对偏心距的符号和数值有关。为了揭示各种因素对构件斜截面强度的影响程度,对矩形截面的重砼试件进行试验。试件尺寸为15×30×240cm,砼试块强度为20～30MPa,纵向配筋为A-Ⅲ级钢筋,其直径为16、20、25和28mm。

Bending performance of TRC-strengthened RC beams with secondary load under chloride erosion

Textile reinforced concrete(TRC)has good bearing capacity,crack resistance and corrosion resistance and it is suitable for repairing and reinforcing concrete structures in harsh marine environments.The four-point bending method was used to analyze the influence of the salt concentration,the damage degree and the coupled effect of the environment and load on the bending performance of TRC-strengthened beams with a secondary load.The results showed that as the salt concentration increased,the crack width and mid-span deflection of the beam quickly increased,and its bearing capacity decreased.As the damage degree increased,the early-stage crack development and mid-span deflection of the beam were less affected and the ultimate bearing capacity significantly decreased.In addition,the coupled effect of the environment and load on the beams with a secondary load was significant.As the sustained load increased,the ultimate bearing capacity of the strengthened beam decreased,and cracks developed faster in the later stage.In addition,the mid-span deflection of the beam decreased at the same load level because of the influence of the initial deflection due to the sustained load corrosion.

Treatment of portal hypertension

Portal hypertension is the main complication of cirrhosis and is defined as an hepatic venous pressure gradient （HVPG） of more than 5 mmHg. Clinically significant portal hypertension is defined as HVPG of 10 mmHg or more. Development of gastroesophageal varices and variceal hemorrhage are the most direct consequence of portal hypertension. Over the last decades significant advancements in the field have led to standard treatment options. These clinical recommendations have evolved mostly as a result of rando.mized controlled trials and consensus conferences among experts where existing evidence has been reviewed and future goals for research and practice guidelines have been pro- posed. Management of varices/variceal hemorrhage is based on the clinical stage of portal hypertension. No specific treatment has shown to prevent the formation of varices. Prevention of first variceal hemorrhage depends on the size/characteristics of varices. In patients with small varices and high risk of bleeding, nonselective β-blockers are recommended, while patients with medium/large varices can be treated with either β-blockers or esophageal band ligation. Standard ofcare for acute variceal hemorrhage consists of vasoacrive drugs, endoscopic band ligation and antibiotics prophylaxis. Transjugular intrahepatic portosystemic shunt （TIPS） is reserved for those who fail standard of care or for patients who are likely to fail （＂early TIPS＂）. Prevention of recurrent variceal hemorrhage consists of the combination of β-blockers and endoscopic band ligation.

Upper gastrointestinal bleeding etiology score for predicting variceal and non-variceal bleeding

AIM： To identify clinical parameters, and develop an Upper Gastrointesinal Bleeding （UGIB） Etiology Score for predicting the types of UGIB and validate the score. METHODS： Patients with UGIB who underwent endoscopy within 72 h were enrolled. Clinical and basic laboratory parameters were prospectively collected. Predictive factors for the types of UGIB were identified by univariate and multivariate analyses and were used to generate the UGIB Etiology Score. The best cutoff of the score was defined from the receiver operating curve and prospectively validated in another set of patients with UGIB. RESULTS： Among 261 patients with UGIB, 47 （18%） had variceal and 214 （82%） had non-variceal bleeding. Univariate analysis identified 27 distinct parameters significantly associated with the types of UGIB. Logistic regression analysis identified only 3 independent factors for predicting variceal bleeding; previous diagnosis of cirrhosis or signs of chronic liver disease （OR 22.4, 95% CI 8.3-60.4, P 〈 0.001）, red vomitus （OR 4.6, 95% CI 1.8-11.9, P = 0.02）, and red nasogastric （NG） aspirate （OR 3.3, 95% CI 1.3-8.3, P = 0.011）. The UGIB Etiology Score was calculated from （3.1× previous diagnosis of cirrhosis or signs of chronic liver disease） ＋ （1.5× red vomitus） ＋ （1.2× red NG aspirate）, when 1 and 0 are used for the presence and absence of each factor, respectively. Using a cutoff ≥ 3.1, the sensitivity, specificity, accuracy, positive predictive value （PPV）, and negative predictive value （NPV） in predicting variceal bleeding were 85%, 81%, 82%, 50%, and 96%, respectively. The score was prospectively validated in cases （46 variceal and 149 another set of 195 UGIB non-variceal bleeding）. The PPV and NPV of a score ≥ 3.1 for variceal bleeding were 79% and 97%, respectively. CONCLUSION： The UGIB Etiology Score, composed of 3 parameters, using a cutoff ≥ 3.1 accurately predicted variceal bleeding and may help to guide the choice of initial therapy for UGIB before endoscopy.

BOOTSTRAP TECHNIQUE FOR ROC ANALYSIS: A STABLE EVALUATION OF FISHER CLASSIFIER PERFORMANCE

This paper presents a novel bootstrap based method for Receiver Operating Characteristic (ROC) analysis of Fisher classifier. By defining Fisher classifier’s output as a statistic, the bootstrap technique is used to obtain the sampling distributions of the outputs for the positive class and the negative class respectively. As a result, the ROC curve is a plot of all the (False Positive Rate (FPR), True Positive Rate (TPR)) pairs by varying the decision threshold over the whole range of the boot- strap sampling distributions. The advantage of this method is, the bootstrap based ROC curves are much stable than those of the holdout or cross-validation, indicating a more stable ROC analysis of Fisher classifier. Experiments on five data sets publicly available demonstrate the effectiveness of the proposed method.

浅析受电弓静态特性曲线

对电力机车受电弓原因造成的故障进行了分析,指出了这些故障和受电弓静态特性曲线的本质联系,提出了解决问题的办法。

Forced Resonance of a Slightly-Curved Hydraulic Pipe Fixed at Two Ends

The ideally straight hydraulic pipe is inexistent in reality. The initial curve caused by the manufacturing or the creep deformation during the service life will change the dynamic character of the system. The current work discusses the effect of the initial curve on the hydraulic pipe fixed at two ends for the first time. Based on the governing equation obtained via the generalized Hamilton’s principle,the potential energy changing with the height of the initial curve is discussed. The initial curve makes the potential energy curve asymmetric,but the system is always monostable. The initial curve also has very important influence on natural frequencies. It hardens the stiffness of the first natural mode at first and then has no effect on this mode after a critical value. On the contrast,the second natural frequency is constant before the critical value but increases while the height of the initial curve exceeds the critical value. On account of the initial value,the quadratic nonlinearity appears in the system. Forced resonance is very different from that of the ideally straight pipe under the same condition. Although the 2∶1 internal resonance is established by adjusting the height of the initial curve and the fluid speed,the typical double-jumping phenomenon does not occur under the initial curve given in the current work. This is very different from the straight pipe in the supercritical region. The work here claims that the initial curve of the hydraulic pipe should be taken into consideration. Besides,more arduous work is needed to reveal the dynamic characters of it.

Development of Morphological Awareness through English Songs:A Case Study

The present study investigated the effects of English songs on morphological development-- inflection, derivation, and compound words. Fifty Chinese EFL students were involved in this study. Two tests were administered to each learner immediately before and after the study. Results from the pre-tests revealed that all three groups with different vocabulary sizes brought some morphological knowledge to the study. The findings exhibited some evidence to support the fact that teaching through English songs can lead to the development of learner＇s receptivity to morphology. However, exposure to the song was insufficient to develop productive knowledge in most of the learners. The study also revealed that groups with smaller vocabulary tended to achieve lower scores than groups with larger vocabulary. Based on these results and previous findings, pedagogical implications were made.

Composite failure prediction of π-joint structures under bending

In this article, the composite π-joint is investigated under bending loads. The ＂L＂ preform is the critical component regard- ing composite π-joint failure. The study is presented in the failure detection of a carbon fiber composite π-joint structure under bending loads using fiber Bragg grating （FBG） sensor. Firstly, based on the general f＇mite element method （FEM） software, the 3-D finite element （FE） model of composite π-joint is established, and the failure process and every lamina failure load of composite π-joint are investigated by maximum stress criteria. Then, strain distributions along the length of FBG are extracted, and the reflection spectra of FBG are calculated according to the strain distribution. Finally, to verify the numerical results, a test scheme is performed and the experimental spectra of FBG are recorded. The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions, and the computational error of failure load is less than 6.4%. Furthermore, it also verifies the feasibility of the damage detection system.

Recent advances in the management of variceal bleeding

Acute haemorrhage from ruptured gastroesophageal varices is perhaps the most serious consequence of uncontrolled portal hypertension in cirrhotic patients.It represents a medical emergency and is associated with a high morbidity and mortality.In those who survive the initial bleeding event,the risks of further bleeding and other decompensated events remain high.The past 30 years have seen a slow evolution of management strategies that have greatly improved the chances of surviving a variceal haemorrhage.Liver cirrhosis is a multi-staged pathological process and we are moving away from a one-size-fits-all therapeutic approach.Instead there is an increasing recognition that a more nuanced approach will yield optimal survival for patients.This approach seeks to risk stratify patients according to their disease stage.The exact type and timing of treatment offered can then be varied to suit individual patients.At the same time,the toolbox of available therapy is expanding and there is a continual stream of emerging evidence to support the use of endoscopic and pharmacological therapies.In this review,we present a summary of the treatment options for a variety of different clinical scenarios and for when there is failure to control bleeding.We have conducted a detailed literature review and presented up-to-date evidence from either primary randomized-controlled trials or meta-analyses that support current treatment algorithms.

A Xanthomonas oryzae pv. oryzae effector, Xop R, associates with receptor-like cytoplasmic kinases and suppresses PAMP-triggered stomatal closure

Receptor-like kinases(RLKs) play important roles in plant immunity signaling; thus, many are hijacked by pathogen effectors to promote successful pathogenesis. Xanthomonas oryzae pv. oryzae(Xoo) is the causal agent of rice leaf blight disease. The strain PXO99 A has 18 non-TAL(transcription activation-like) effectors; however, their mechanisms of action and host target proteins remain largely unknown. Although the effector XopR from the Xoo strain MAFF311018 was shown to suppress PAMP-triggered immune responses in Arabidopsis, its target has not yet been identified. Here, we show that PXO99 A XopR interacts with BIK1 at the plasma membrane. BIK1 is a receptor-like cytoplasmic kinase(RLCK) belonging to the RLK family of proteins and mediates PAMP-triggered stomatal immunity. In turn, BIK1 phosphorylates XopR. Furthermore, XopR suppresses PAMP-triggered stomatal closure in transgenic Arabidopsis expressing XopR. In addition, XopR is able to associate with RLCKs other than BIK1. These results suggest that XopR likely suppresses plant immunity by targeting BIK1 and other RLCKs.

Topography of spinal column and kidney receptors as illustrated by microsystem of the foot

OBJECTIVE:To test the accuracy of the distribution of reflective zones on the feet as proposed by William Fitzgerald using the spine and kidney receptors as reference points.METHODS:Spine and feet lengths were measured first along straight lines and then again,taking into consideration the anatomical curves.The spinal column was further measured with regard to its individual regions(cervical,thoracic,lumbar,sacrum-coccyx).Straight-line measurements were taken with the help of an anthropometer.Measurements that took into account all of the curves were performed with the opisometer(also known as a "map measurer").All the measurements were accurate to within 1 mm.The study subjects were a healthy,physically fit 16-year-old female student and a 53-year-old male office employee exposed to an average dose of physical exercise.RESULTS:The kidney receptor in the foot did not reflect onto the predetermined lumbar section of the spinal column as measured along the straight line or with regard to curves.Instead,in both subjects the kidney receptor reflected onto the thoracic spine.CONCLUSION:Te particular level of the spinal cord that innervates the given organ controls the distribution of receptors of individual organs in the foot.