Optimality of Group Testing with Differential Misclassification

Group testing is a method that can be used to estimate the prevalence of rare infectious diseases,which can effectively save time and reduce costs compared to the method of random sampling.However,previous literature only demonstrated the optimality of group testing strategy while estimating prevalence under some strong assumptions.This article weakens the assumption of misclassification rate in the previous literature,considers the misclassification rate of the infected samples as a differentiable function of the pool size,and explores some optimal properties of group testing for estimating prevalence in the presence of differential misclassification conforming to this assumption.This article theoretically demonstrates that the group testing strategy performs better than the sample by sample procedure in estimating disease prevalence when the total number of sample pools is given or the size of the test population is determined.Numerical simulation experiments were conducted to evaluate the performance of group tests in estimating prevalence in the presence of dilution effect.

Can environmental sustainability be decoupled from economic growth? Empirical evidence from Eastern Europe using the common correlated effect mean group test

The European Union(EU) and Organisation for Economic Co-operation and Development(OECD) aim to develop long-term policies for their respective member countries. Having observed increasing dangers to the environment posed by rising economic growth, they are seeking pathways to enable policy action on economic growth and environmental sustainability. Given the facts in theoretical and empirical studies, this study assessed the validity of the decoupling hypothesis by investigating asymmetricity in the relationship between environmental sustainability and economic growth in nine Eastern European countries from 1998 to 2017 using the cross-section augmented Dickey-Fuller(CADF) unit root, panel corrected standard error(PCSE), common correlated effect mean group(CCEMG), and Dumitrescu Hurlin causality approaches. Both population growth and drinking water are used as controlled variables. The outcomes establish strong cointegration among all the variables of interest. According to the results of CCEMG test, economic growth exerts short-term environmental degradation but has long-term environmental benefits in Eastern Europe;and population growth and drinking water exert a positive effect on environmental sustainability in both the short-and long-run. The results of Dumitrescu Hurlin causality test indicate that environmental sustainability is unidirectionally affected by economic growth. Based on these outcomes, we suggest the following policies:(1) the EU and OECD should implement member-targeted policies on economic growth and fossil-fuel use towards regulating industrial pollution, water use, and population control;and(2) the EU and OECD member countries should invest in environmental technologies through green research and development(R&D) to transform their dirty industrial processes and ensure productive energy use.

Nested Group Testing Procedure

We investigated the false-negative,true-negative,false-positive,and true-positive predictive values from a general group testing procedure for a heterogeneous population.We show that its false(true)-negative predictive value of a specimen is larger(smaller),and the false(true)-positive predictive value is smaller(larger)than that from individual testing procedure,where the former is in aversion.Then we propose a nested group testing procedure,and show that it can keep the sterling characteristics and also improve the false-negative predictive values for a specimen,not larger than that from individual testing.These characteristics are studied from both theoretical and numerical points of view.The nested group testing procedure is better than individual testing on both false-positive and false-negative predictive values,while retains the efficiency as a basic characteristic of a group testing procedure.Applications to Dorfman’s,Halving and Sterrett procedures are discussed.Results from extensive simulation studies and an application to malaria infection in microscopy-negative Malawian women exemplify the findings.

SARS-CoV-2 Pooled Testing Methodology for PCR Testing Applied in Private Laboratory in Armenia

Since the beginning of COVID-19 pandemics many countries were facing challenges with testing capacity recourse limitations. Throughout the waves of the pandemic countries were trying to address the existing constrains exploring solutions to increase the testing capacity with more cost-effective approaches. Pooled methodology was one of the methods which many have validated and used. It is evident that in case of pooled sample testing the sensitivity becomes lower, however the variation highly depends on the pool size as well as the incidence rate at the certain point. Armenia as well as many other countries has adopted regulations for mandatory COVID-19 PCR testing for all the travelers. Current study aimed to explore the efficiency of COVID-19 pooled PCR testing for nasopharyngeal swabs of individuals with no symptoms in a time period with good epidemiological state of the infection. Nasopharingeal swab samples from individuals were collected. The manual extraction of RNAs of samples was performed after pooling up to 5 samples. The pools with Cycle Threshold (CT) of < 37 were considered positive and were retested individually. In total 28,015 samples were grouped in 667 pools of which 57 were positive. The total number of positive samples was 65. The median difference (CT-pool–CT samples) was 2.4 (ranging from–3.0 to 8.9). The correlation of CT of pools and positive samples was positive. The correlation coefficient r = 0.84, P < 0.000, 95% CI range 0.7423 to 0.9243). The total economic saving when using pools compared to the individual testing was 72%. The minor difference between CT values of pools and samples can be explained by the dilution effect in the pool. However, the positive correlation between the values as well as the amount of cost saving demonstrate that pooling on nasopharyngeal samples for COVID-19 PCR testing can be a good method for efficient screening with significant resource saving. One of the most important advantages of the proposed method is the fact that samples are pooled prior extraction, which avoids the possibilities with misinterpretation of IC due to low yield of RNA in the extraction process.

Aquifer Test求群孔抽水试验水文地质参数

在水文地质条件复杂的地区,往往采用大型的群孔抽水试验充分揭露含水层特征,获取水文地质参数。用Aquifer Test软件求解水文地质参数,则方便实用、简捷高效,可快速输出拟合图形和求参结果。Aquifer Test提供了丰富的求参方案,求参必须结合当地当时的水文地质条件实际情况考虑,选择适合的方案和时空数据求取水文地质参数。

Modelling the utility of group testing for public health surveillance

In epidemic or pandemic situations,resources for testing the infection status of individuals may be scarce.Although group testing can help to significantly increase testing capabilities,the(repeated)testing of entire populations can exceed the resources of any country.We thus propose an extension of the theory of group testing that takes into account the fact that definitely specifying the infection status of each individual is impossible.Our theory builds on assigning to each individual an infection status(healthy/infected),as well as an associated cost function for erroneous assignments.This cost function is versatile,e.g.,it could take into account that false negative assignments are worse than false positive assignments and that false assignments in critical areas,such as health care workers,are more severe than in the general population.Based on this model,we study the optimal use of a limited number of tests to minimize the expected cost.More specifically,we utilize information-theoretic methods to give a lower bound on the expected cost and describe simple strategies that can significantly reduce the expected cost over currently known strategies.A detailed example is provided to illustrate our theory.

A Group Testing Problem on a n- Item Set Containing Two Defective Ones

In this paper we study a group testing model ФX, Y,, XY. In other words, we consider a n-item set containing exactly two defective ones. The purpose of this paper is to find out the two defective items with a worst-case minimum number of tests, each of which will indicates whether the subset being tested contains all good （normal） items or not and in the latter case, it is not sure that the tested subset is of one defective （bad） item or two. Based on the M-sharp algorithm obtained in the previous paper and some combinatorial skills, we derive an almost optimal algorithm for the so called n-problem.

A New Algorithm for a Group Testing Problem on a n-Coin Set Containing One Defective One

In this paper we study further on a group testing problem of identifying the defective from a n-coin set containing one defective coin with a balance without weight. The defective coin is not of the same weight as each of the normal ones. We derive a new testing algorithm which can tell out the defective from the n-coin set with the worst-case minimum number of tests.

Shake table test of soil-pile groups-bridge structure interaction in liquefiable ground

This paper describes a shake table test study on the seismic response of low-cap pile groups and a bridge structure in liquefiable ground. The soil profile, contained in a large-scale laminar shear box, consisted of a horizontally saturated sand layer overlaid with a silty clay layer, with the simulated low-cap pile groups embedded. The container was excited in three E1 Centro earthquake events of different levels. Test results indicate that excessive pore pressure （EPP） during slight shaking only slightly accumulated, and the accumulation mainly occurred during strong shaking. The EPP was gradually enhanced as the amplitude and duration of the input acceleration increased. The acceleration response of the sand was remarkably influenced by soil liquefaction. As soil liquefaction occurred, the peak sand displacement gradually lagged behind the input acceleration; meanwhile, the sand displacement exhibited an increasing effect on the bending moment of the pile, and acceleration responses of the pile and the sand layer gradually changed from decreasing to increasing in the vertical direction from the bottom to the top. A jump variation of the bending moment on the pile was observed near the soil interface in all three input earthquake events. It is thought that the shake table tests could provide the groundwork for further seismic performance studies of low-cap pile groups used in bridges located on liquefiable groun.

Comparative Analysis of Group Sequential Designs Tests for Randomized Controlled Clinical Trials: A Model Study on Two-Sided Tests for Comparing Two Treatments

Clinical trials are usually long term studies and it seems impossible to reach all required subjects at the same time. Performing interim analyses and monitoring results may provide early termination of trial after obtaining significant results. The aim of this study is comparing group sequential tests in respect to advantage of sample size reduction and early termination. In this study, 4 test types used in group sequential designs were compared with fixed sample size design test and each other. Comparisons were done according to two-sided tests for comparing two treatments. In this sense, 1080 models were performed. In models, 2 different Type I errors, 2 different powers, 5 different analysis groups, 6 different effect sizes and 9 different variances selections were considered. All test types increased the maximum sample size in different manner, compared with fixed sample size design. Each test had different critical values to reject H0 hypothesis, at the same type I error rate and number of analyses conditions. Selection of test type used in group sequential designs depends on a few characteristics, as reducing sample size, early termination and detecting minimal effect size. Test performance is highly related with selected Type I error rate, power and number of analyses. In addition to these statistical characteristics, researchers should decide test type with respect to other trial conditions as the issue of trial, reaching subjects easy or not and importance of early termination.

A Study on Unified Testing Method for IEC 61850 Based Server with Focus on Setting Group Function

The digital substation system consists of an Intelligent Electronic Device (IED) which requires information for the supervision, protection, and control, as well as a client operating system for substation operation. IEC 61850 communication standard has been defined for information exchange between heterogeneous digital devices in such substations. Currently, the Korea Electric Power Corporation (KEPCO) digital substation system uses unbuffered reporting and Generic Object Oriented Substation Events (GOOSE) communication functions for monitoring, protection and control automation. However, it is expected that the Setting Group function will be needed to operate adaptive intelligent substation system. The Setting Group function is advantageous in that it is possible to change the setting of the IED in one unified way through the client operating system, rather than changing the correction value of an IED through different manufacturer-based engineering tools. In order to utilize the Setting Group function of the IED in real substation scenario, it is necessary to test both the communication function with the host operating device and the electric functional test to ensure that correction value is properly changed. In this paper, we introduce the IEC 61850 Setting Group function, and propose a method that can integrate communication function and electrical function test of an IED conforming to the setting group functionality. We also tested the Setting Group function of the actual IED device through the proposed integrated functional test method and analyzed the results. We were able to simplify the process of testing both the electrical and communication signals in digital substations.

On the Power Performance of Test Statistics for the Generalized Rayleigh Interval Grouped Data

In this paper, the weighted Kolmogrov-Smirnov, Cramer von-Miss and the Anderson Darling test statistics are considered as goodness of fit tests for the generalized Rayleigh interval grouped data. An extensive simulation process is conducted to evaluate their controlling of type 1 error and their power functions. Generally, the weighted Kolmogrov-Smirnov test statistics show a relatively better performance than both, the Cramer von-Miss and the Anderson Darling test statistics. For large sample values, the Anderson Darling test statistics cannot control type 1 error but for relatively small sample values it indicates a better performance than the Cramer von-Miss test statistics. Best selection of the test statistics and highlights for future studies are also explored.

钙质砂地基中群桩基础荷载传递特性研究

为研究钙质砂地基中群桩基础承载过程中的性能特征,开展不同桩距条件下群桩基础静载试验.得到不同桩距条件下群桩的Q-S曲线和S-lgt曲线,测得3d、4.5d、6d(d为桩径)群桩在静载条件下的极限承载力F_(u),研究各个桩段的桩身轴力、桩侧摩阻力以及桩端阻力的变化趋势.研究结果表明:群桩的Q-S曲线为缓变型,S-lgt曲线为渐变型,桩基承载变形大致分为稳定、渐进以及破坏3个阶段,相较于3d群桩,4.5d、6d群桩沉降发展更缓慢,F_(u)更高;同等桩距下,钙质砂地基表现出比陆源砂地基更强的群桩效应,钙质砂地基中群桩最佳桩距应在4.5d~6d之间.该研究为群桩在钙质砂地基中的应用提供数据支撑和理论参考.

基于群桩基础改进的变径微型桩承载特征研究

为改善输电杆塔微型桩基础的承载特性、降低用料成本,提出基于微型群桩改进的变径微型桩基础型式。通过高原山区等截面微型群桩原型试验与数值反演模型相互验证,对3种变径微型单桩进行模拟,并与微型群桩承载效果进行对比分析,揭示变径微型桩的承载特征与变形机理。结果表明:微型群桩基础(2×2单桩)由于承台和群桩效应的影响,其抗压和抗拔承载力分别大于和小于对应的单桩承载力总和;双扩径微型桩(扩径部分直径=2×等截面桩身直径)的极限抗拔和抗压承载力约为等截面微型桩的3.8倍和2.7倍,土体变形集中于扩径部位,且变形量较大,表现为多支点摩擦-端承桩特性;于桩顶增设承台可有效改善双扩径单桩的下压及水平承载性能,与未增设承台相比,承载力分别提高了2.1倍和2.2倍。研究表明,通过扩展部分桩径并增设承台使微型单桩性能提升至等截面群桩水平的方法可行,对送变电建设具有工程意义。

成组法疲劳试件个数选取方法研究

目的 在成组法疲劳试验过程中,确定最少疲劳试件个数判据,获取有效可靠的疲劳试验结果。方法基于疲劳可靠性的基本原理,在疲劳寿命对数正态分布的假设下,根据t分布理论,结合船舶及海洋工程一般构件具有95%置信度和可靠度p=97.72%下的P-S-N曲线的基本要求,推算出相应置信度和可靠度下5%误差限度内的疲劳试件个数与允许的最大变异系数数值的对应关系,以此作为成组法疲劳试验最少试件个数的判据,开展典型节点的疲劳试验。结果 得到了具有95%置信度的百位估计值Np,并通过线性相关系数r,判断对数疲劳应力Y=lg S与X=lg Np之间线性相关的程度,采用最小二乘法对对数疲劳寿命lg Np和对数疲劳应力lg S进行线性拟合,得到了具有95%置信度的P-S-N曲线,与IIW规范中相应的曲线一致。结论 文中给出的成组法疲劳试验个数确定方法是合理、可靠的,为船舶与海洋工程结构物典型焊接接头成组法疲劳试验个数的确定提供了依据。

微型木桩的群桩效应研究

木材广泛存在于我国村镇中,其取材加工方便,价格低廉,用作村镇住宅的基础结构,可有效减少村镇住宅的能源消耗,符合绿色建筑理念。本文以微型木桩为研究对象,通过离心机模型试验和有限元数值分析,研究了微型木桩在砂土和粉质黏土土层条件下的群桩承载力和群桩效应系数。结果表明,微型木桩的群桩效应系数η在砂土中大于1,在黏土中小于1,受桩土刚度比的影响较小;桩径减小改变了群桩最优桩间距,砂土中微型木桩η随着桩的距径比Sa/D的增大逐渐增大,在Sa/D=6时出现峰值,常规桩在Sa/D=3时达到最大,微型木桩最优桩间距大于常规桩;黏土中,微型木桩η峰值对应的Sa/D=4小于常规桩η峰值对应的Sa/D=6,微型木桩最优桩间距小于常规桩;微型木桩群桩效应系数随内摩擦角和不排水抗剪强度的增大而减小,随距径比的增大先增加后减小,随桩数的增加而增大。

大学体育课堂协同体测项群同源教学的实践探索

根据体测项群的运动性质即动作发力、技术促进、技能辅助、成绩提高等基础练习具有交叠之处,研究速度、耐力、力量、柔韧与灵敏素质等同源因子在教学中对身体素质的影响有重要意义.选取大学体育课选项班作为实验研究对象,查找体测成绩进行统计学分析,所得结果作为课题研究的参考值;实验课上匹配体测项群同源因子的对比教学,结果显示5项身体素质均有明显提高:对同源因子俯冲弹体、蜻蜓点水、乾坤大挪移能够有效提高仰卧起坐、坐位体前屈、立定跳远成绩(P<0.01),而对引体向上成绩无统计学意义上的提高(P>0.05);五向星形跑对短跑、耐力速度800 m、1000 m及肺活量成绩有非常显著(P<0.01)的影响;课上进行同源教学程序简易,便于把控运动强度及运动量,尤其在提高学生体测成绩方面发挥重要作用,同源教学可以激发练习热情,使学生自觉主动参与,适合在其他选项课推广应用.

2022年辽宁省水稻中熟组区试铁岭点参试品种的农艺性状与产量的相关分析

选择2022年辽宁省水稻中熟组区试铁岭点参试的14个品种,通过观测其株高、总粒数、穗长、每穴穗数、结实率、千粒重及产量,采用相关性分析、差异显著性分析等方法研究参试品种的农艺性状与产量的关系。结果表明:每穗总粒数与穗长正相关,每穗总粒数与每穴穗数负相关,产量与千粒重负相关。铁岭地区选择分蘖数适中的每穗总粒数多的大穗小粒品种可能更容易高产,但是也容易出现穗下部二次枝梗籽粒灌浆变差、结实率降低的情况,需要改良水稻种植方法与栽培技术,提高结实率,可以更进一步的提高水稻产量。

变刚度地基上隔震结构群桩基础动力响应试验研究

通过控制输入地震动持时压缩比和强度的方法,提出了变刚度地基上桩基基础隔震结构振动台模型试验方法,并结合已完成的不同地基上桩基基础隔震结构系列振动台模型试验,分析了地基刚度变化对隔震结构群桩基础动力学特性的影响规律。结果表明,结构-土体相对刚度比和输入地震动强度显著影响隔震结构群桩基础弯矩反应,强震下结构-土体相对刚度比越大,隔震结构群桩基础中间桩体上部弯矩反应幅值增大越显著,而中间桩体下部弯矩幅值较小。当输入加速度峰值和结构-土体相对刚度比R大于一定限值时,群桩基础震陷显著增加,群桩基础承台转动反应强烈,同时群桩基础桩顶水平位移在主震后出现明显的单边累积水平位移,说明强震作用下地基刚度变化过程中隔震结构群桩基础上部更易出现地震破坏,而群桩基础震陷与基础承台强烈转动反应的共同作用可能是导致隔震结构群桩基础上部弯矩骤增的主因。

扩底桩竖向承载特性及群桩效应研究

为探明扩底群桩竖向承载特性,采用扩底桩筏结构,开展单桩(扩径比分别为1.5、2.0、2.5、3.0)和桩筏(扩径比为2)基础静载模型试验,分析其荷载传递规律,并建立桩间距为3.75、4.00、4.50、5.00倍桩直径时扩底桩筏基础有限元模型,研究桩间距对群桩效应影响。结果表明:扩底单桩和扩底桩筏结构荷载沉降曲线均为缓变型;扩底桩极限承载力随扩径比增大而逐渐增大,扩径比2.5~3.0时极限承载力增幅变缓,建议扩底桩扩径比取2.5~3.0;由于桩土共同沉降,桩间土压缩,桩土作用更充分,扩底桩筏基础中心桩侧摩阻力荷载分担比比扩底单桩增大了17.71%;群桩效应系数随桩间距增大而逐渐增大,桩间距为4.5~5.0倍桩直径时群桩效应系数增幅较小,群桩效应较弱,建议扩底桩筏基础桩间距取值不小于4.5倍桩直径。