Egger’s test与Begg’s test的功效差异比较与原因分析

目的比较Meta分析中Egger’s test、Begg’s test方法在检测发表偏倚时的功效(检验效能)差异并探讨其原因。方法收集28篇相关文献建立数据库,采用倾向性缺失手段产生11份新的Meta分析资料样本,然后行Egger’stest、Begg’s test检验其发表偏倚,比较结果的差异,并同时做纳入研究的异质性和样本含量的正态性检验,寻找影响发表偏倚检验功效的因素。结果①11个倾向性缺失样本中,Begg’s test有5项的P值小于0.05,而Egger’s test的P值都大于0.27;②异质性检验P值全部小于0.05,正态性检验有9项P值小于0.05。结论①倾向性缺失导致发表偏倚,此时Begg’s test较Egger’s test更容易检出发表偏倚的真实情况,而Egger’s test的检验效能此时并不高;②导致Egger’s test对发表偏倚的检验效能下降的可能因素有样本含量非正态和异质性等。

稳健统计和Grubbs检验法在实验室间能力验证结果分析中的应用——以海洋生物体中总汞测定结果为例

报道了用稳健统计技术(Robust statistical technique)和Grubbs检验法,在实验室间能力验证海洋生物体样品总汞含量检测结果评定分析中的应用。结果分析表明,用稳健统计技术和Grubbs检验法,对多家实验室参加的海洋生物体样品总汞含量检测能力验证数据中的离群值进行评定,其结果具有一致性,相比而言,稳健统计技术的数据处理和计算程序更加科学、直观和简洁方便,可很好地反映多个实验室能力验证的数据统计分析和结果评价。

异常值检测中GRUBBS法的改进

GRUBBS检验法在异常值检测中一种较常用的质控方法.本文针对其易出现假受控和假失控现象,提出一种改进算法,即对前4次数据进行修匀处理,合理采集两次有效数据,减少了方差过大过小出现的现象,从第5次开始进行质控.理论分析和实验均表明,新方法减少了假受控与假失控的机会,仿真结果也表明了改进算法的有效性.

基于Grubbs检验法的沉降监测数据粗差探测及剔除

介绍了Grubbs检验法的基本理论,提出了基于Grubbs检验法的粗差探测实现方法,利用该方法对某市地面沉降监测数据进行粗差探测及剔除,并对处理结果进行了探讨分析。研究结果表明,基于Grubbs检验法的粗差探测与剔除方法能快速识别出异常数据,可有效应用于大量数据中的粗差探测及剔除。

基于Grubbs的雷达精度检测数据分析

运用数理统计的理论、观点和方法,针对试验次数有限的情况,阐述了一种基于Grubbs法则的均方差校验方法,解决了雷达精度的检验、判定和决策问题,为指挥决策提供了依据,使雷达精度检验理性化。实例验证了该方法的正确性、严谨性。

基于grubbs检验的中水压力数据清洗

在优化中水动力配置策略中,中水水压监控是其中重要的一环,在水压监控中,如何能够正确的分辨出异常的测量水压值是由于水头损失过大,还是设备误报的原因,关系到此后的数据分析结果是否准确合理。通过将高校中水数据中中水的压力数据按照日期进行聚集查询、对查询结果进行Grubbs检验,通过Grubbs检验识别异常数据,并根据识别结果将原始的压力数据中的异常数据删除,从而达到数据清洗的目的,为中水给水的后续研究提供了完整准确的数据支持。该研究方法不但能够为水压监控中异常数据的数据处理提供参考,对其他测量设备出现类似异常的数据清洗也具有一定的借鉴意义。

Validity Consideration in Designing an Oral English Test

To make oral test accurately reflect the actual English spoken ability of candidates and play its role in guiding and promoting the improvement of English learners in the teaching, we must ensure that the design of scientific questions, the feasibility and validity of judgments to make an accurate and fair measurement of testers' language ability.

基于数据流的K-S变化检测的动态多目标规划算法

为了更加准确地判断环境是否发生变化并快速追踪动态多目标规划问题(dynamicmulti-objectiveoptimization problem,DMOP)当前时刻的Pareto前沿,提出了一种基于数据流的Kolmogorov-Smirnov(K-S)变化检测的动态多目标规划(DSK-SDMOP)算法。该算法以NSGA-Ⅱ为基础,通过数据流建立2个时刻的检验窗口,再利用K-S检验基于数据流的Pareto最优前沿是否发生变化,检测2个窗口的数据是否服从同一分布来判断环境是否发生变化,并就环境变化的剧烈程度实行相应的应答机制,以提高对环境的适应程度。利用基于数据流的K-S检测方法,对环境变化不会过于敏感,而且不用提前假设对应目标值的分布,易于操作。通过5个动态多目标规划标准测试函数对该算法进行测试,并和现有的2种算法进行对比分析,结果表明该算法处理动态多目标规划问题具有良好的性能。

New fecal test for non-invasive Helicobacter pylori detection:A diagnostic accuracy study

AIM To assess the diagnostic accuracy of a new fecal test for detecting Helicobacter pylori(H. pylori), using ^(13)Curea breath test as the reference standard, and explore bacterial antibiotic resistance. METHODS We conducted a prospective two-center diagnostic test accuracy study. We enrolled consecutive people≥ 18 years without previous diagnosis of H. pylori infection, referred for dyspepsia between February and October 2017. At enrollment, all participants underwent 13 C-urea breath test. Participants aged over 50 years were scheduled to undergo upper endoscopy with histology. Participants collected stool samples 1-3 d after enrollment for a new fecal investigation(THD fecal test). The detection of bacterial 23 S rRNA subunit gene indicated H. pylori infection. We also used the index diagnostic test to examine mutations conferring resistance to clarithromycin and levofloxacin. Independent investigators analyzed index test and reference test standard results blinded to the other test findings. We estimated sensitivity, specificity, positive(PPV) and negative(NPV) predictive value, diagnostic accuracy, positive and negative likelihood ratio(LR), together with 95% confidence intervals(CI).RESULTS We enrolled 294 consecutive participants(age: Median 37.0 years, IQR: 29.0-46.0 years; men: 39.8%). Ninetyfive(32.3%) participants had a positive ^(13)C-urea breath test. Twenty-three(7.8%) participants underwent upper endoscopy with histology, with a full concordance between ^(13)C-urea breath test and histology in detecting H. pylori infection. Four(1.4%) out of the 294 participants withdrew from the study after the enrollment visit and did not undergo THD fecal testing. In the 290 participants who completed the study, the THD fecal test sensitivity was 90.2%(CI: 84.2%-96.3%), specificity 98.5%(CI:96.8%-100%), PPV 96.5%(CI: 92.6%-100%), NPV 95.6%(CI: 92.8%-98.4%), accuracy 95.9%(CI: 93.6%-98.2%), positive LR 59.5(CI: 19.3-183.4), negative LR 0.10(CI: 0.05-0.18). Out of 83 infected participants identified with the THD fecal test, 34(41.0%) had bacterial genotypic changes consistent with antibiotic-resistant H. pylori infection. Of these, 27(32.5%) had bacterial strains resistant to clarithromycin, 3(3.6%) to levofloxacin, and 4(4.8%) to both antibiotics. CONCLUSION The THD fecal test has high performance for the non-invasive diagnosis of H. pylori infection while additionally enabling the assessment of bacterial antibiotic resistances.

Increased intestinal permeability in inflammatory bowel diseases assessed by iohexol test

AIM:To study intestinal permeability(IP) and its relationship to the disease activity in patients with inflammatory bowel diseases(IBD)-Crohn's disease(CD) and ulcerative colitis(UC).METHODS:Fifty-eight patients with active IBD(32 with CD and 26 with UC) and 25 healthy controls consented to participate in the study.The clinical activity of CD was estimated using the Crohn's Disease Activity Index(CDAI),and the endoscopic activity of UC using the Mayo scoring system.IP was assessed by the rise in levels of iohexol,which was administered orally(25 mL,350 mg/mL) 2 h after breakfast.Three and six hours later serum(SIC mg/L) and urine(UIC g/mol) iohexol concentrations were determined by a validated HPLC-UV technique.RESULTS:In the CD group,SIC values at 3 h(2.95 ± 2.11 mg/L) and at 6 h after ingestion(2.63 ± 2.18 mg/L) were significantly higher compared to those of healthy subjects(1.25 ± 1.40 mg/L and 1.11 ± 1.10 mg/L,respectively,P < 0.05).UIC(g/mol) values were also higher in patients,but the differences were significant only for UIC at 6 h.Significant positive correlation(P < 0.05) was found between the CDAI and IP,assessed by SIC at 3 h(r = 0.60) and 6 h(r = 0.74) after the ingestion.In comparison to controls,SIC and UIC of UC patients were higher in the two studied periods,but the differences were significant at 6 h only.Significantly higher values of SIC(P < 0.05) were found in patients with severe endoscopic activity of UC compared to those of patients with mild and moderate activity(3.68 ± 3.18 vs 0.92 ± 0.69 mg/L).CONCLUSION:Serum levels of iohexol at 3 h and 6 h after its ingestion reflect increased IP,which is related to the disease activity in patients with IBD.

Mechanical Characterization of Electroplated Ni Films by Micro-tensile Testing

Mechanical properties of structural materials are particularly important for design, performance realization and reliability analysis of microelectromechanical systems （MEMS）. Furthermore, accurate database of mechanical properties at the micro scale can provide indispensable reference for establishing MEMS standard. Electroplated nickel film is one of the most favored structural materials used in MEMS, thus its mechanical properties has been studied for many years. However, the measured values show large scatter in Yotmg＇s modulus of nickel film. Young＇s modulus and yield stress of electroplated nickel film are measured by using a micro-tensile testing instrument. The tensile load applied on the specimen is measured by a load cell with accuracy 0.25 mN directly, without additional friction. Through measuring the axial stiffness coefficient of the tensile instnunent in situ, the tensile strain of the specimen is obtained by using two-serial spring model. The electroplated nickel films were fabricated from sulfarnate baths, and the gauge section is 500μm long and 10μm wide nominally, and thickness range between 25 μm and 50μm. The obtained Young＇s modulus from tensile testing is 83＋6 GPa for nickel specimens electroplated at current density of 20 mA/cm2 and it increases to 124＋5 GPa as current density is decreased to 10 mA/cm2. The phenomena are interpreted in terms of porosity of microstructure. The higher current density produced rnicrostucture with low density and high volume fraction of pores, and the microstructure of high porosity corresponds to a lower modulus. The measured values of Young＇s modulus are consistent with those of calculated from the exponential empirical formula between Young＇s modulus and porosity. The micro-tensile testing instrument can also be used for mechanical measurement of other MEMS films.

Study on soil-pile-structure-TMD interaction system by shaking table model test

The success of the tuned mass damper (TMD) in reducing wind-induced structural vibrations has been well established. However, from most of the recent numerical studies, it appears that for a structure situated on very soft soil, soil-structure interaction (SSI) could render a damper on the structure totally ineffective. In order to experimentally verify the SSI effect on the seismic performance of TMD, a series of shaking table model tests have been conducted and the results are presented in this paper. It has been shown that the TMD is not as effective in controlling the seismic responses of structures built on soft soil sites due to the SSI effect. Some test results also show that a TMD device might have a negative impact if the SSI effect is neglected and the structure is built on a soft soil site. For structures constructed on a soil foundation, this research verifies that the SSI effect must be carefully understood before a TMD control system is designed to determine if the control is necessary and if the SSI effect must be considered when choosing the optimal parameters of the TMD device.

Serum 1,3-beta-D-glucan as a noninvasive test to predict histologic activity in patients with inflammatory bowel disease

BACKGROUND 1,3-beta-D-glucan(BG)is a ubiquitous cell wall component of gut microorganisms.We hypothesized that the serum levels of BG could reflect active intestinal inflammation in patients with inflammatory bowel disease.AIM To determine whether the serum BG concentrations correlate with intestinal inflammation.METHODS A prospective observational study was performed in a tertiary referral center,from 2016 to 2019,in which serum BG was determined in 115 patients with Crohn’s disease(CD),51 with ulcerative colitis(UC),and 82 controls using a photometric detection kit.Inflammatory activity was determined by ileocolonoscopy,histopathology,magnetic resonance enterography,and biomarkers,including fecal calprotectin(FC),C-reactive protein,and a panel of cytokines.The ability of BG to detect active vs inactive disease was assessed using the area under the receiver operating characteristic curve.In subgroup analysis,serial BG was used to assess the response to therapeutic interventions.RESULTS The serum BG levels were higher in CD patients than in controls(P=0.0001).The BG levels paralleled the endoscopic activity in CD patients and histologic activity and combined endoscopic and histologic activity in both CD and UC patients.The area under the curve(AUC)in receiver operating characteristic analysis to predict endoscopic activity was 0.694[95%confidence interval(CI):0.60-0.79;P=0.001]in CD,and 0.662(95%CI:0.51-0.81;P=0.066)in UC patients.The AUC in receiver operating characteristic analysis to predict histologic activity was 0.860(95%CI:0.77-0.95;P<0.001)in CD,and 0.786(95%CI:0.57-0.99;P=0.015)in UC patients.The cut-off values of BG for both endoscopic and histologic activity were 60μg/mL in CD,and 40μg/mL in UC patients.Performance analysis showed that the results based on BG of 40 and 60μg/mL were more specific for predicting endoscopic activity(71.8%and 87.2%for CD;and 87.5%and 87.5%for UC,respectively)than FC(53.3%and 66.7%for CD;and 20%and 80%for UC,respectively);and also histologic activity(60.5%and 76.3%for CD;and 90.0%and 95.0%for UC,respectively)than FC(41.7%and 50.0%for CD;and 25%and 50%for UC,respectively).Regarding the clinical,endoscopic,and histologic activities,the BG levels were reduced following therapeutic intervention in patients with CD(P<0.0001)and UC(P=0.003).Compared with endoscopic(AUC:0.693;P=0.002)and histologic(AUC:0.868;P<0.001)activity,no significant correlation was found between serum BG and transmural healing based on magnetic resonance enterography(AUC:0.576;P=0.192).Positive correlations were detected between BG and IL-17 in the CD(r:0.737;P=0.001)and the UC group(r:0.574;P=0.005),and between BG and interferon-gamma in the CD group(r:0.597;P=0.015).CONCLUSION Serum BG may represent an important novel noninvasive approach for detecting mucosal inflammation and therapeutically monitoring inflammatory bowel diseases,particularly in CD.

Property changes of anchor grout calcined ginger nuts admixed with fly ash and quartz sand after accelerated ageing tests

Calcined ginger nuts admixed by fly ash and quartz sand (CGN-(F+S)) has been validated to be basically compatible to earthen sites as an anchor grout. Accelerated ageing tests including water stability test, temperature and humidity cycling test, soundness test and alkali resistance test are conducted with the objective to further research the property changes of CGN-(F+S) grout. Density, surface hardness, water penetration capacity, water permeability capacity, soluble salt, scanning electron microscopy (SEM) images and energy dispersive spectrometry (EDS) spectrum of these samples have been tested after accelerated ageing tests. The results show that densities of samples decrease, surface hardness, water penetration capacity and water permeability capacity of samples increase generally. Besides, soluble salt analysis, SEM and EDS results well corroborate the changes. Based on the results it can be concluded that property changes are most serious after temperature and humidity cycling test, followed by water stability, soundness and alkali resistance test in sequence. But in general, CGN-(F+S) still has good durability.

基于Grubbs通信系统试验数据处理

通信系统试验数据的异常值不能随意舍弃,只能舍弃确定性因素导致的异常数据,本文基于Grubbs准则判断异常数据与剔除方法。同时,采用Grubbs准则对通信系统的试验数据进行了数据处理,并结合Matlab给出了应用示例。

Non-Contact Stress Measurement during Tensile Testing Using an Emat for SH₀-Plate Wave and Lamb Wave

The stress on a test specimen during tensile testing is generally measured by a strain gauge. This method has some problems in that it would influence the measurement conditions of the tensile test and can evaluate only the position at which the strain gauge is attached. The acoustoelastic method is proposed as a method replacing the strain gauge method. However, an ultrasonic sensor with a piezoelectric oscillator requires a coupling medium to inject an ultrasonic wave into a solid material. This condition, due to the error factor of the stress measurement, makes it difficult for the ultrasonic sensor to move on the specimen. We then tried to develop a non-contact stress measurement system during tensile testing using an electromagnetic acoustic transducer (EMAT) with an SH0-plate wave and S0-Lamb wave. The EMAT can measure the propagation time in which the ultrasonic wave travels between a receiver and a transmitter without a coupling medium during the tensile testing and can move easily. The interval between the transmitter and the receiver is 10mm and can be moved along the parallel direction or the vertical direction of the tensile load. The transit time was measured by a cross-correlation method and converted into the stress on the test specimen using the acoustoelastic method. We confirmed that the stress measurement using an SH0-plate wave was superior to that with an S0-Lamb wave.

探索Grubbs、F及T检验法在人造板能力验证中的运用

文章利用数理统计中Grubbs、F及T检验法对4家实验室能力验证结果进行分析评价。以中密度纤维板中甲醛释放量测试为案例,采用Grubbs、F及T检验组合的方法进行数据统计分析,验证了利用Grubbs、F及T检验法统计分析能力验证中数据过少的情况是可行的。

Model test of negative Poisson’s ratio cable for supporting super-largespan tunnel using excavation compensation method

In recent years,there is a scenario in urban tunnel constructions to build super-large-span tunnels for traffic diversion and route optimization purposes.However,the increased size makes tunnel support more difficult.Unfortunately,there are few studies on the failure and support mechanism of the surrounding rocks in the excavation of supported tunnel,while most model tests of super-large-span tunnels focus on the failure characteristics of surrounding rocks in tunnel excavation without supports.Based on excavation compensation method(ECM),model tests of a super-large-span tunnel excavation by different anchor cable support methods in the initial support stage were carried out.The results indicate that during excavation of super-large-span tunnel,the stress and displacement of the shallow surrounding rocks decrease,following a step-shape pattern,and the tunnel failure is mainly concentrated on the vault and spandrel areas.Compared with conventional anchor cable supports,the NPR(negative Poisson’s ratio)anchor cable support is more suitable for the initial support stage of the super-large-span tunnels.The tunnel support theory,model test materials,methods,and the results obtained in this study could provide references for study of similar super-large-span tunnels。

Determination of reduced Young s modulus of thin films using indentation test

The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method （FEM） aimed to reveal the effect of punch size on the indentation behavior of the film/substrate system. Based on the FEM results analysis, two methods was proposed to separate film＇s reduced Young＇s modulus from a film/substrate system. The first method was based on a new weight function that quantifies film＇s and substrate＇s contributions to the overall mechanical properties of the film/substrate system in the flat cylindrical indentation test. The second method, a numerical approach, including fitting and extrapolation procedures was put forward. Both of the results from the two methods showed a reasonable agreement with the one input FE model. At last, the effect of maximum indentation depth and the surface micro-roughness of the thin film on the reduced Young＇s modulus of the film/substrate system were discussed. The methods proposed in the present study provide some new conceptions on evaluating other properties of thin films, e.g. creep, for which a flat-ended punch is also employed.

Information content method for evaluating diagnostic tests and its comparison of power with other methods

This paper derives the variance of the information content and develops its statistical inference method. We describe the relations between information content and sensitivity, specificity, efficiency, prevalence rate. If sensitivity, specificity and efficiency are fixed, the closer to 0. 5 the prevalence rate is, the more the information content. If prevalence rate and efficiency are fixed, the closer to each other the sensitivity and specificity are, the more the information content. We compare the power of information content method, efficiecy test, Youden's index test and kappa coefficient method. The information content method has higher power than the other methods in most conditions. It is especially sensitive to the difference between two sensitivities. It comes to conclusion that the information content method has more virtues than the other methods mentioned in this paper.