Research on the Content Validity of the CET-4 Fast Reading Test

Content validity is an important part of language testing.In this paper,the content validity of the CET-4 fast reading test is analyzed in terms of expected response and text input.The result of final research shows that the content validity of the fast reading test is high with some limitations proposed.

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.

Nondestructive testing method of wood moisture content based on a planar capacitance sensor model

For our research, a new hybrid experimental-computational method is presented. We applied a least squares fitting method （LSFM） to reconstruct the wood moisture content （WMC） from the data measured with a planar capacitance sensor. A boundary element method （BEM） was used to compute the relationship between capacitance and the dielectric constant. A functional relationship between MC and the dielectric constant was identified by LSFM. The agreement of this final computation result with the experimental data indicates that this method can be used to estimate the WMC quickly and effectively with engineering analysis. Compared with popular statistical methods, a large number of experiments are avoided, some costs of testing are reduced and the efficiency of testing is enhanced.

ADPRT-MEDIATED DECREASE OF CELLULAR NAD CONTENT AND THE DETECTION OF CHEMICALLY INDUCED DNA DAMAGE DEVELOPMENT OF A NEW SHORT-TERM SCREENING TEST FOR MUTAGENS

It was found that the DNA-damaging agents N-methyl-N’-nitro-N-nitrosoguanidine（MNNG）,methyl-methanesulphonate（MMS）and 4-nitroquinoline-N-oxide（4NQO）could stimulate ADP-ribosyl transferase（ADPRT）activity and reduce the cellular NAD content in a dose-dependent way.The reduction of NAD after DNA damage could be partially or completelyprevented by ADPRT inhibitors,3-aminobenzamide or nicotinamide,which showed noinfluence on reduction of NAD induced by metabolic blocking agents.Therefore,a simpleand specific method to detect DNA-damaging mutagens by measuring ADPRT-mediateddecrease of cellular NAD content was explored.Using β-naphthofiavone,a mixed functionoxygenase inducer,together with induced or uninduced human amnion FL cells,it was foundthat aflatoxin B1,benzo（a）pyrene,2-acetylaminofluorene,9,10-dimethylanthracene andethylcarbamate could induce the ADPRT-mediated decrease of cellular NAD content,while4-acetylaminofluorene,anthracene,isopropyl-N-（3-chlorophenyl）-carbamate,β-propiolactone,γ-butyrolactone,cyclophosphamide and safrol could not.The results indicate that this isa cheap and specific method to detect DNA damage caused by chemical carcinogens/mutagenswith a spccificity approaching that of the unscheduled DNA synthesis assay.

Effects of Sodium Chloride Stress on Growth of Sweet Potato Plantlets in vitro and Ion Content

[Objective] This study aimed to investigate the salt-tolerance mechanism of sweet potato.[Method]Two sweet potato varieties of Xu 25-2(salt-tolerant cultivar)and Triumph 100(salt-sensitive cultivar)were treated by sodium chloride with the concentration of 0 mmol/L and 100 mmol/L.After 20 days,Na+ content and Na+/K+ ratio in the roots,shoots and leave were determined by the flame photometer,while dry weight and fresh weight of roots,shoots and leave in different varieties were also studied.[Result]The growth of two sweet potato varieties was inhibited under salt stress,so the plant became shorter,leaf and root became fewer,dry weight of roots and leave decreased,but seedlings of Xu 25-2 were inhibited slightly.Furthermore,Na+ content and Na+/K+ ratio in roots,shoots and leaves of two sweet potato varieties increased.Na+ content of salt-tolerant Xu 25-2 was low in roots,shoots and leaves,while Na+ content of salt-sensitive Triumph 100 was high in shoots and leave of seedlings,but the change range of Xu 25-2 was less than that of Triumph 100.[Conclusion]The lower Na+ content and Na+/K+ ratio in leaves under salt stress were the most important characteristics for salt-tolerance of sweet potato varieties.

Validation Study on Listening Test in Newly Reformed CET- 6： A Case Study of CET-6 Official Sample

Listening Comprehension test of CET-6 has a great adjustment in its item types and weighting of score since December,2015, however, there have been few researches concerning the validity of newly innovated CET-6 listening comprehension test.This paper tries to explore the construct validity and content validity of it. Based on the comparison between the test contents of lis-tening and the test requirements in CET syllabus,it is found that CET-6 listening shows good content relevance. Structural equa-tion modeling(SEM) was used to investigate the construct validity of CET-6 listening, which demonstrates that it mainly tests stu-dents' ability to understand details and inference, while ignoring socio-linguistic competence and psych-physiological compe-tence. Therefore, certain changes are desirable to increase the validity of the listening part of CET-6.

基于Gitest Ⅲ的听力过关测试试题项目分析

通过利用GitestⅢ软件,作者对湖南城市学院英语专业2009年1月听力过关测试全部客观题进行了较为详细的项目分析,检测了试题的信度和效度,并针对分析结果提出在设计听力测试客观题方面应注意的问题及建议。

A new shear rheological model for a soft interlayer with varying water content

The rheological behavior of a soft interlayer is critical to understanding slope stability, which is closely related to the water content of the soft interlayer. This study used the soft interlayer of the Permian Maokou Formation in Southwest China as an example to perform ring shear creep tests with different water content amounts. The effect of water content on the creep properties of the soft interlayer was analyzed, and a new shear rheological model was established. This research produced several findings. First, the ring shear creep deformation of the soft interlayer samples varied with the water content and the maximum instantaneous shear strain increment occurred near the saturated water content. As the water content increased, the cumulative creep increment of the samples increased. Second, the water content significantly affected the long-term strength of the soft interlayer, which decreased with the increase of water content, exhibiting a negative linear correlation. Third, a constitutive equation for the new rheological model was derived, and through fitting of the ring shear creep test data, the validity and applicability of the constitutive equation were proven. This study has developed an important foundation for studying the long-term deformation characteristics of a soft interlayer with varying water content.

Effects of water content on the shear behavior and critical state of glacial till in Tianmo Gully of Tibet, China

Glacial tills are widely distributed in Tibet, China, and are highly susceptible to landslides under intense rainfalls. Failures of the slope during rainfall are closely related to the shear behavior of glacial tills at different moisture conditions. This study investigates the shear behavior and critical state of saturated and unsaturated glacial tills through a series of drained direct shear tests. The tests were conducted on two types of compacted glacial tills with different water contents and total normal stresses. A strain softening mode of failure is observed for all water content conditions accompanied by noticeable dilation. Dilatancy is found to decrease with increasing water content. Unsaturated samples showed increased rates of dilation as water content is decreased for all applied normal stresses a behavior which cannot be predicted well by classical stressdilatancy models. Furthermore, it was found that the Critical State Line(CSL), plotted on the(e-ln) plane, can be used to define the shear behavior of unsaturated glacial tills at different water contents.The CSL of saturated glacial tills run parallel to this line. The experimental results in this study are aimed to provide a basic understanding to the underlying failure mechanisms of glacial tills.

SiteTesting with IRA-935 Hygrometer and Statistical Analyses

A brief description of infrared IRA-935 water vapour measuring instrument is presented and integrated vertical water vapour content W 0 in the atmosphere at Gaomeigu and Fenghuangshan sites and precision analyses are given in the paper. The daily variation and distributions of W 0 in a whole year and monthly average W 0 measurements at these two sites are discussed in more detail. The statistical results of the observational data in the whole year are also analysed and discussed.

Validity Considerations in Designing an English Reading Test

Validity is one of the essential factors in evaluating test quality. In order to design a high-quality reading test paper, such aspects should be taken much more considerations as test specification, theoretical construct, test content and test tasks & item types.

Mechanical Characterization of Rubber Latex-Based Carpets (Hevea bresiliensis): Influence of Rubber Latex Content and Fiber Fabrics (Cotton and Mosquito Nets) on Wear Resistance of Rubber Latex-Based Carpets

This work focuses on the development of carpets from sand, fabrics of cotton fiber and mosquito nets and rubber latex. Following a study on the choice of the best formulations, the quantity of rubber latex used for shaping varies between 14% and 18% (latex/sand + latex ratio) for the carpet with the fabric of mosquito nets and between 16% and 18% for the one made with the fabric of cotton fiber. Thus, with a mixture of sand, fiber fabrics (cotton and mosquito nets) and rubber latex, carpets were developed. In addition, the wear test carried out on these samples indicates that it is possible to produce carpets with the new material made of rubber sand and latex: SABLATEX At room temperature. Following the characterization test, it resorts to only 16% latex with cotton fiber fabric, allowing to have carpets with good mechanical characteristics.

Calorific values and ash contents of different parts of Masson pine trees in southern China

Calorific value of plants is an important parameter for evalu- ating and indexing material cycles and energy conversion in forest eco- systems. Based on mensuration data of 150 sample sets, we analyzed the calorific value （CV） and ash content （AC） of different parts of Masson pine （Pinus massoniana） trees in southern China using hypothesis testing and regression analysis. CV and AC of different tree parts were almost significantly different （P〈0.05）. In descending order, ash-free calorific value （AFCV） ranked as foliage 〉 branch 〉 stem bark 〉 root 〉 stem wood, and AC ranked as foliage 〉 stem bark 〉 root 〉 branch 〉 stem wood. CV and AC of stem wood from the top, middle and lower sections of trees differed significantly. CV increased from the top to the lower sections of the tnmk while AC decreased. Mean gross calorific value （GCV） and AFCV of aboveground parts were significantly higher than those of belowground parts （roots）. The mean GCV, AFCV and AC of a whole tree of Masson pine were 21.54 kJ/g, 21.74 kJ/g and 0.90%, re- spectively. CV and AC of different tree parts were, to some extent, cor- related with tree diameter, height and origin.

中子成像技术在元素分析中的应用

中子成像作为一种快速、直观的无损检测技术,在核工业、航空航天、新能源、地质、考古、先进制造等多个领域得到广泛应用。中子成像利用中子不带电、穿透能力强、对轻元素敏感、可区分同位素和近邻元素等特性,非常适合开展含氢元素、近邻元素和同位素等材料的无损检测。通过概述中子成像技术的基本原理及特点,并结合中国先进研究堆(CARR)中子成像装置上的应用案例,重点综述了国内外中子成像技术在储氢材料、燃料电池、岩石、核燃料元件、古代文物等领域的典型应用。随着中子成像技术的不断发展和广泛应用,有望为我国更多领域研究提供更强有力的技术支撑。

黄土盾构隧道开挖围岩扰动特性模型试验研究

为了探究不同含水率和埋深等工况下的黄土盾构隧道开挖对围岩的扰动作用特征,采用相似模型试验,首先通过三轴试验测定了不同含水率下原状黄土物理参数及强度指标,通过大量试配得到了不同含水率下与原状黄土强度指标参数相似的试验用土。其后,考虑盾构隧道盾尾间隙特征,开展不同含水率及埋深等组合工况下盾构开挖模拟试验,通过微型土压力传感器、百分表等监测元件以及数字图像技术等手段,分析了不同工况下地层变形、地表沉降和围岩应力的变化规律。研究发现:含水率较低时,围岩的自稳能力强;含水率越高,埋深越大,开挖对地层的扰动作用也越大;地表最大沉降值与含水率呈正相关,与埋深呈负相关;围岩剩余应力随含水率和埋深的增大而增大,但当含水率增大至一定值(26.6%)时,围岩剩余应力骤减;基于不同含水率下的围岩应力及变形发展规律,可将黄土含水率分为自稳、形变以及松动含水率,基于含水率和埋深引起的围岩松动情况,可将不同工况下的黄土盾构隧道围岩压力作用模式按照形变压力和松动压力计算,以更加适应黄土地层的特性。

含泥量对砂类硫酸盐渍土工程特性的影响分析

为了明确含泥量对砂类硫酸盐渍土的盐胀和力学特性的影响,人工配制了不同细粒土含量的砂类硫酸盐渍土,在1%和3%(质量分数,下同)含盐量单向冻结盐胀试验的基础上,选取了细粒土含量为5%、15%、30%和40%的砂样进行常温、低温三轴剪切试验。研究结果表明:此试验条件下,不同级配砂类硫酸盐渍土的冻结温度为-0.7~-0.1℃,当砂样孔隙溶液浓度在冻结温度之上达到饱和时,降温过程中会首先生成盐结晶;1%含盐量条件下,高细粒土含量(≥30%)砂样的起胀温度在4~9℃之内,而低细粒土含量砂样的起胀温度在0℃附近,3%含盐量砂样的起胀温度为20~23℃;试验含水率和细粒土含量通过影响土体中自由水的含量对盐冻胀产生显著影响。在力学特性方面,随着细粒土掺量的增加,砂类硫酸盐渍土的抗剪强度表现出先增大后减小的趋势,细粒土由增强摩擦转变为颗粒间的“润滑”作用;此外,冻结后砂土转变为承载能力更强的“土-盐-冰骨架结构”,抗剪强度大幅提高,并呈现出明显的脆性破坏特征,由于冻结砂土受相对温度的影响,随着含盐量的增加,破坏应力呈先减小后增大的趋势。

6个橡胶树新品种在德宏州的区域性试验研究

为筛选出适宜德宏植胶区的橡胶树新品种,引进了热研879、热垦628、热研73397、IAN873、热垦525、湛试32713这6个橡胶树新品种,在瑞丽市进行生产性试种,并对引进品种的茎围、产量、干胶含量、死皮率、抗寒性等指标进行了评价。结果表明:(1)开割前热垦628、热研73397、IAN873的茎围增粗表现较好,第8年达开割标准;开割后湛试32713,热垦628、热研73397和热垦525的茎围平均净增粗较高、速生特性好。(2)平均株次干胶产量表现为热研879极显著高于对照,热垦628显著高于对照;单位面积干胶产量以热垦628与热研879较高,均与对照之间差异极显著;热垦628的平均干胶含量较低,显著低于对照,其他品种与对照之间差异不显著。(3)死皮率表现为热垦628>湛试32713>IAN873>热研879>热研525>云研77-4(CK)>热研73397,4、5级死皮率表现为热垦525>热垦628>热研73397>IAN873>热研879>湛试32713>云研77-4(CK)。(4)热垦628和湛试32713的抗寒性表现较好,IAN873、热研879和热垦525的抗寒性表现较差。鉴于6个橡胶品种在德宏州种植的综合表现,立地环境较好林段可优先选择种植高产品种热研879,以往有轻微寒害发生的林段可选择高产抗寒品种热垦628。

The microbial content of unexpired pasteurized milk from selected supermarkets in a developing country

Objective:To determine the presence and levels of microbes in unexpired pasteurized milk from randomly selected supermarkets in Kingston,Jamaica.Methods:The quantitative study used a stratified random sampling technique in the selection of the 20 representative milk samples from six(6) supermarkets.Microbiological tests such as methylene blue reduction,standard plate count(SPC),coliform plate count(CPC),purity plate culture,gram staining and biochemical tests were performed to examine the microbes in purchased unexpired pasteurized milk.Results:One sample(BCr016) had a pH of 4.0.a rancid odour and curdled appearance.It decolourized within one hour during the methylene blue reduction test and was classified as class 4 milk.Seven of the samples were sterile with no microbe growth on the plate count agar and violet red bile salt agar(VRBA).The milk samples that appeared to be safe for consumption were all 10,11,12 and 13 days before expiration.The VRBA sample BCr016,had a colony count of 13 400 CFU/ mL.There was the presence of Escherichia coli in sample LCr021 which had a standard plate count of 1 580 SPC/mL and a coliform count of 500 CFU/mL.Enterobacter sp.was present in colonies from BCr016 and all the other milk samples.Conclusions:Unacceptable levels of Entembacter spp.and Escherichia coli were found in most of the samples.Effective measures to ensure safe milk for human consumption such as the phosphatase test and methylene blue reduction test should be routinely performed on each batch of milk processed by dairy plants.

基于固结试验的高原湖相沉积泥炭土渗透特性研究

随着中国昆明地区的快速发展,泥炭土地基的处置需求日益增多。为了明确高原湖相沉积泥炭土在固结过程中的渗透特性及其影响因素,通过固结试验方法测定六个场地的渗透系数kv,分析固结压力P、孔隙比e及有机质含量wu等因素对其渗透性能的影响并建立了渗透模型。试验结果表明:在逐级加载条件下,泥炭土的渗透系数kv和孔隙比e随固结压力P增大而减小,P越大,kv和e下降幅度越小,且kv的下降主要发生在主、次固结阶段;泥炭土渗透系数kv随有机质含量wu增加而增大,但kv并非单一受wu的影响,还会受到有机质的分解度的影响,不同分解度的泥炭土其孔隙特征和渗透性能均不同;高原湖相沉积泥炭土的渗透系数可选用lg(1+e)-lgkv渗透模型进行计算,能较好反映出e与kv的变化关系。