Effects of bifenthrin on Daphnia magna during chronic toxicity test and the recovery test

The acute and chronic toxic effects of bifenthrin on Daphnia magna were studied. The results showed that 24 h-EC 50 , 48 h-LC 50 and 96 h-LC 50 of bifenthrin on D. magna were 3.24, 12.40 and 1.40 μg/L respectively. And the LOEC and NOEC of bifenthrin were 0.02 and 0.004 μg/L respectively. The recovery test of bifenthrin on Daphnia magna was presented. Daphnia magna(F 0 generation) were exposed during 21 d to different bifenthrin concentrations. Offspring(animals from the first and third brood: F 1(1st) and F 1(3rd), respectively) were transferred to a free pesticide medium during a 21 d recovery period. In this recovery study, survival, growth, reproduction(mean total young per female, onset of reproduction and number broods per female) and the intrinsic rate of natural increase (r) were assessed as parameters. Reproduction such as number of young per female as well as length was still reduced in F 1(1st) generation daphnids from parentals(F 0) exposed to the bifenthrin. However F 1(3rd) individuals from parentals exposed to pesticide concentrations were able to restore reproduction when a recovery period of 21 d was allowed, but the length of F 1(3rd) from parentals exposed to the 0.5 and 0.75 μg/L bifenthrin concentration was still significantly effected(P<0.05).

The differences and similarities between two-sample t-test and paired t-test

临床研究中经常遇到比较实验组和对照组之间的结果。双样本t检验(又称为独立样本t检验)和配对t检验可能是运用于比较两个样本之间均值的最广泛的统计方法。然而,这两种方法的运用会产生混淆,从而导致使用不当。本文中,我们讨论了这两种t检验之间的异同性,并运用三个范例来阐述双样本t检验和配对t检验的计算过程。

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.

The Statistical Significance Test of Regional Climate Change Caused by Land Use and Land Cover Variation in West China

The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database （GLCCD） that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are： （1） The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. （2） The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. （3） The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. （4） The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.

Comparison of T-2 Toxin and HT-2 Toxin Distributed in the Skeletal System with That in Other Tissues of Rats by Acute Toxicity Test

Twelve healthy rats were divided into the T-2 toxin group receiving gavage of 1 mg/kg T-2 toxin and the control group receiving gavage of normal saline. Total relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system（thighbone, knee joints, and costal cartilage） were significantly higher than those in the heart, liver, and kidneys（P 〈 0.05）. The relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system（thighbone and costal cartilage） were also significantly higher than those in the heart, liver, and kidneys. The rats administered T-2 toxin showed rapid metabolism compared with that in rats administered HT-2 toxin, and the metabolic conversion rates in the different tissues were 68.20%-90.70%.

An Analysis of English Listening Test-taking Skills and Strategies for College Entrance Examination under A New Field of View

As we all know, listening has always been a weak point in students' English learning. Doing English listening tests often encounter some difficulties. At the same time, many students have a serious fear of listening test, and listening itself has a transient effect, so students should be able to calmly cope with the listening test to play the best level. In addition, students need to understand the types of the college entrance examination listening test , listen to more listening practice and lay a solid foundation. Students should also master some listening skills, so as to obtain high scores.

The Danger within:Covid-19 Affinity for ACE2 Receptors in Adipose Tissue and Testes.The Protective Effects of Estradiol,Fitness,and Weight Management

The imminent danger of the Covid-19 pandemic has accelerated research in pharmaceuticals that either target the viral Spike proteins fusion with ACE2 receptors,or the infectious RNA replication that often overwhelms immune defences.The scope of this review was to elucidate the main human vulnerabilities to Covid-19,including the accumulation of ACE2 receptors in testes,adipose tissue,thyroid,heart and kidneys that escalate viral affinity in males,the aged,and certain medical conditions,including diabetes,CVD,and pulmonary diseases.Pre-existing inflammation inherent in obesity may exacerbate the“cytokine storm,”a rampaging immune reaction during the course of Covid-19 that is deleterious to the host.We examined the molecular dynamics illustrating the action of new therapeutics necessary for Covid-19 patients;the estradiol advantage hypothesis;alternative therapies including hormone replacement procedures and mesenchymal stem cells;plus preventive and protective interventions.The current perspective also explored the primary components of dysregulated health predisposing individuals to Covid-19,including hormonal imbalance,increased lipids and lipoproteins,thyroid dysfunction,degraded fitness,and age-related testosterone decline accompanied by cortisol increase that provokes stress eating behaviours and weight accumulation.Obesity increases the probability of Covid-19 infection due to its abundance of ACE2 receptors;while physical activity may decrease Covid-19 vulnerability,by reducing fat and increasing muscle mass that manifests a relatively inhibited ACE2 expression.Several weight management solutions feature lasers and radiofrequency which diminish subcutaneous adiposity but do not enhance fitness.A data metanalysis of seven recently published clinical studies on 95 obese individuals,73 males and 22 females with an average BMI of 30.9,demonstrated visceral fat reduction combined with increased skeletal muscle mass.It also revealed a statistically significant decrease in BMI,lipids,lipoproteins,inflammation and toxicity as measured by CRP,Creatinine and Bilirubin respectively,juxtaposed by optimally healthier levels of Cortisol,Testosterone,Free T3,IGF-1,Insulin,and the appetite controlling hormones Leptin and Ghrelin.

驱梅汤联合多西环素对梅毒患者免疫炎症反应及外周血单核细胞TLR2、Foxp3 mRNA的影响

目的探讨驱梅汤联合多西环素对梅毒患者免疫炎症反应及外周血单核细胞(PBMCs)Toll样受体2(TLR2)、叉头框蛋白3(Foxp3)mRNA水平的影响。方法选取2016年12月至2020年12月邢台市第二医院收治的107例梅毒患者作为研究对象。采用随机信封法分为常规组(n=53)和实验组(n=54)。常规组采用多西环素治疗,实验组采用多西环素联合驱梅汤治疗。比较两组梅毒滴度快速血浆反应素试验(RPR)转阴率、临床疗效、T淋巴细胞亚群(CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+))、PBMCs TLR2、Foxp3 mRNA相对表达量及不良反应发生情况。结果实验组治疗后3、6个月RPR转阴率高于常规组(P<0.05);实验组总有效率高于常规组(P<0.05);治疗30 d后实验组CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)高于常规组(P<0.05);治疗30 d后实验组PBMCs TLR2、Foxp3 mRNA相对表达量低于常规组(P<0.05);实验组不良反应发生率低于常规组(P<0.05)。结论驱梅汤联合多西环素治疗梅毒患者能提高转阴率,疗效确切,且安全性较高,这可能与抑制PBMCs TLR2、Foxp3 mRNA表达有关。

Teaching ,Learning &Testing-Reconsideratios on the Pathway for Improving College English Teaching and Learning

The persistent and indefatigable efforts of all the College English teachers have brought about great changes in colle ge English teaching and learning in t he past few years.These changes,however,may be summa rized within the framework of a shift from one form of test -oriented teaching and learnin g to another.In reality,much has yet to be done to improve the language abilities of the studen ts.Under such circumstances,nationwi de English examinations or unified e xaminations at var-ious levels,are bound to make things even worse by misleading college and university teachers in their teaching practice.In this p aper,the author claims that College English teachers and their students should be freed from t he confinement of the unified examin ations so that they will be able to build a real learner -centr ed curriculum as far as possible according to their own needs.Finally,some tentative ideas are presented on the pathway for imp roving the quality of the College English teaching and learning.

A Novel Approach for Developing a Linear Regression Model within Logistic Cluster Using Scikit-Learn

Due to the rapid development of logistic industry, transportation cost is also increasing, and finding trends in transportation activities will impact positively in investment in transportation infrastructure. There is limited literature and data-driven analysis about trends in transportation mode. This thesis delves into the operational challenges of vehicle performance management within logistics clusters, a critical aspect of efficient supply chain operations. It aims to address the issues faced by logistics organizations in optimizing their vehicle fleets’ performance, essential for seamless logistics operations. The study’s core design involves the development of a predictive logistics model based on regression, focused on forecasting, and evaluating vehicle performance in logistics clusters. It encompasses a comprehensive literature review, research methodology, data sources, variables, feature engineering, and model training and evaluation and F-test analysis was done to identify and verify the relationships between attributes and the target variable. The findings highlight the model’s efficacy, with a low mean squared error (MSE) value of 3.42, indicating its accuracy in predicting performance metrics. The high R-squared (R2) score of 0.921 emphasizes its ability to capture relationships between input characteristics and performance metrics. The model’s training and testing accuracy further attest to its reliability and generalization capabilities. In interpretation, this research underscores the practical significance of the findings. The regression-based model provides a practical solution for the logistics industry, enabling informed decisions regarding resource allocation, maintenance planning, and delivery route optimization. This contributes to enhanced overall logistics performance and customer service. By addressing performance gaps and embracing modern logistics technologies, the study supports the ongoing evolution of vehicle performance management in logistics clusters, fostering increased competitiveness and sustainability in the logistics sector.

T3 Loop Test试验误起柴油机原因分析及改进

基于TRICON平台的反应堆保护系统T3 Loop Test试验主要验证Tricon机柜与非安全相关一层DCS系统及第三方系统的硬接线连接的正确性。在方家山机组调试期间发生了T3试验误起柴油机的事件,通过对事件的分析,发现了T3 Loop Test试验程序存在的设计隐患,并进行了改进,成功消除了该项设计隐患,保障了核电站的安全稳定运行。

A New Maximum Test via the Dependent Samples t-Test and the Wilcoxon Signed-Ranks Test

A maximum test in lieu of forcing a choice between the two dependent samples t-test and Wilcoxon signed-ranks test is proposed. The maximum test, which requires a new table of critical values, maintains nominal α while guaranteeing the maximum power of the two constituent tests. Critical values, obtained via Monte Carlo methods, are uniformly smaller than the Bonferroni-Dunn adjustment, giving it power superiority when testing for treatment alternatives of shift in location parameter when data are sampled from non-normal distributions.

An Approximate Hotelling T²-Test for Heteroscedastic One-Way MANOVA

In this paper, we consider the general linear hypothesis testing (GLHT) problem in heteroscedastic one-way MANOVA. The well-known Wald-type test statistic is used. Its null distribution is approximated by a Hotelling T2 distribution with one parameter estimated from the data, resulting in the so-called approximate Hotelling T2 (AHT) test. The AHT test is shown to be invariant under affine transformation, different choices of the contrast matrix specifying the same hypothesis, and different labeling schemes of the mean vectors. The AHT test can be simply conducted using the usual F-distribution. Simulation studies and real data applications show that the AHT test substantially outperforms the test of [1] and is comparable to the parametric bootstrap (PB) test of [2] for the multivariate k-sample Behrens-Fisher problem which is a special case of the GLHT problem in heteroscedastic one-way MANOVA.

Statistical Tests of Hypothesis Based Color Image Retrieval

This paper proposes a novel method based on statistical tests of hypotheses, such as F-ratio and Welch’s t-tests. The input query image is examined whether it is a textured or structured. If it is structured, the shapes are segregated into various regions according to its nature;otherwise, it is treated as textured image and considered the entire image as it is for the experiment. The aforesaid tests are applied regions-wise. First, the F-ratio test is applied, if the images pass the test, then it is proceeded to test the spectrum of energy, i.e. means of the two images. If the images pass both tests, then it is concluded that the two images are the same or similar. Otherwise, they differ. Since the proposed system is distribution-based, it is invariant for rotation and scaling. Also, the system facilitates the user to fix the number of images to be retrieved, because the user can fix the level of significance according to their requirements. These are the main advantages of the proposed system.

Comparison of the results of T-Test from different versions of Epi Info

Objective： To take advantage of Epi Info to manage and analyze disease data. Methods： After selecting the living examples for independent sample T-Test, Epi Info 5.00, 5.01a（Chinese）, 6.00, 6.04 b, 6.04 d, 2000, 2002（Chinese）were used to do the independent sample T-Test on the two living examples. Then, Intercooled StataT, Microsoft Excel（2002） and SPSS 10.0 for Windows were used to verify the results. Results： The statistical results from the Epi Info 5.00, 5.01a（Chinese） and 6.00 were the same while that from Epi Info 6.04 b, 6.04 d, 2000,2002 （Chinese）, Intercooled StataT, Microsoft Excel（2002） and SPSS 10.0 for Windows were identical In independent sample T-Test,. But the former result is different with the latter. Conclusion： There was an error in the result of T-Test from Epi Info 6.00 and former versions. Thus, it＇s important to be alert to select the versions of Epi Info to manage and analyze disease data. On the other hand, it＇s also quite pivotal to distinguish the adopted Epi Info versions when referring to the articles ane use the statistical results.

FY-2F Satellite In-orbit Test Review Passed

The FY-2F satellite recently passed its in-orbit test review and can be put into operational use. Experts from Chinese Academy of Sciences, China Meteorological Administration, CASC, China Electronics Technology Group Corporation, State Administration of Science, Technology and Industry for National Defense,

线性回归模型偏F检验与t检验等价性的一种证明方法

在运用线性回归模型进行预测或控制之前,必须首先对线性回归模型中每个自变量对因变量影响程度的统计显著性进行逐个分析。可通过构造偏F统计量进行F检验或构造t统计量进行t检验,而对线性回归模型来说,本质上偏F检验和t检验是等价的,可使用矩阵分块的方法展现这一结论的原理和证明过程。

优化T-SPOT.TB在区分脊柱结核与其他脊柱感染中的诊断效能

目的 探讨结核感染T细胞斑点试验(T-SPOT.TB)在脊柱结核(STB)鉴别诊断中的效能,并通过受试者工作特征(ROC)曲线最佳截断值优化诊断效能。方法 收集2010年1月—2019年5月某院脊柱感染患者的临床资料,包括术前T-SPOT.TB检测结果、白细胞计数、C-反应蛋白、血沉、降钙素原和结核抗体等相关数据,根据诊断标准进行临床诊断,分析T-SPOT.TB在术前诊断STB与其他脊柱感染中的灵敏度和特异度,评价优化后的T-SPOT.TB指标的诊断效能。结果 共纳入132例患者,其中78例(59.09%)为STB,54例(40.91%)为非结核脊柱感染。T-SPOT.TB在鉴别诊断STB方面的灵敏度为67.68%,特异度为66.67%。单因素logistic回归分析显示,与非结核脊柱感染比较,T-SPOT.TB检测诊断STB的OR值为4.188(95%CI:1.847~9.974,P<0.001)。优化T-SPOT.TB评价指标,通过绘制ROC曲线,确定ESAT-6、CFP-10、CFP-10+ESAT-6在STB和非结核脊柱感染鉴别诊断中的最佳截断值,分别为12.5、19.5、36,曲线下面积(AUC)分别是0.765 6、0.741 5、0.778 6,均具有较好的诊断性能,其中以CFP-10+ESAT-6的AUC最高。CFP-10+ESAT-6特异性斑点数在脊柱结核诊断中性能更佳,其诊断准确度为75.56%,较优化前T-SPOT.TB的67.42%高。结论 T-SPOT.TB检测在区分STB与非结核脊柱感染方面显示出较高的诊断效能,T-SPOT.TB检测呈阳性,尤其是当CFP-10+ESAT-6的斑点数超过36时,提示脊柱结核的可能性较大。

腹腔镜下卵巢囊肿剔除术对患者卵巢功能、炎症因子及T淋巴细胞亚群水平的影响

【目的】探讨腹腔镜下卵巢囊肿剔除术对患者卵巢功能、炎症因子及T淋巴细胞亚群水平的影响。【方法】选取2019年1月至2023年1月本院妇科收治的76例卵巢囊肿患者,根据手术方法不同分为对照组和观察组,每组38例。对照组行开腹卵巢囊肿剔除术治疗,观察组行腹腔镜下卵巢囊肿剔除术治疗,比较两组手术前后卵巢功能[雌二醇(E 2)、促卵泡激素(FSH)、黄体生成素(LH)]、炎症因子[白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、C反应蛋白(CRP)]及T淋巴细胞亚群水平(CD3^(+)、CD4^(+)及CD4^(+)/CD8^(+))。【结果】两组术后3个月FSH、LH均升高,但观察组低于对照组(P<0.05);两组术后3个月E 2均降低,但观察组高于对照组(P<0.05)。观察组患者术后IL-6、TNF-α、CRP水平低于对照组,差异有统计学意义(P<0.05)。两组患者术前CD4^(+)、CD4^(+)/CD8^(+)比较,差异无统计学意义(P>0.05);术后1 d,两组患者血清CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)均较术前明显降低,但观察组高于对照组,差异均有统计学意义(P<0.05);观察组患者术后3 d血清CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)恢复至术前水平。【结论】腹腔镜下卵巢囊肿剔除术可有效促进患者卵巢功能恢复,并减轻机体炎症反应,提高T淋巴细胞亚群水平,减轻对机体细胞免疫功能的抑制,有利于患者术后康复。

胸痛发作时床边即时检测心肌钙蛋白T诊断急性心肌梗死的价值

目的确定胸痛症状发作后不同时间间隔内,床边心肌肌钙蛋白T(point of care troponin-T testing,POCT-cTnT)对急性心肌梗死(acute myocardial infarction,AMI)的诊断性能,了解其在快速排除AMI方面的意义。方法这项回顾性研究包括了2019年1月至2022年12月期间出现胸痛症状的6024例患者。在入院时测量了POCT-cTnT和中心实验室cTnI水平。通过按时间窗口划分的受试者工作特征(receiver operating characteristics,ROC)分析,评估POCT-cTnT在诊断AMI时的准确性。结果总体而言,POCT-cTnT诊断AMI的AUC为0.826(95%CI:0.816~0.836),灵敏度和特异度分别为72.81%和86.26%。根据胸痛发作的时间进行区间分组(<3 h、3~6 h、6~12 h、12~24 h、24~72 h和≥72 h),6~12 h以后的分组AUC值分别为0.918、0.928、0.920和0.908,差异无统计学意义(P>0.05),均要高于6 h时以内的组(P<0.001);根据胸痛发作时间点进行分组,≥8 h组的AUC为0.921,阴性预测值(negative predictive value,NPV)98.1%和阴性似然比(negative likelihood ratio,-LR)0.11,其AUC高于≥3 h、≥2 h、≥1 h和overall组(P<0.05),而与≥4 h以后的各时间组相比,差异无统计学意义(P>0.05)。结论胸痛发作时间对单次检测POCT-cTnT诊断AMI的性能存在一定的影响,结合胸痛发作至就诊时间,可能提高其诊断或排除AMI的可靠性。在胸痛发作4 h后,单次POCT-cTnT检测能可靠地诊断或排除AMI;当胸痛发作8 h后,其诊断或排除AMI方面具有更高的可靠性。