Strengthening reinforced concrete beams using prestressed glass fiber-reinforced polymer-Part II:Analytical study

INTRODUCTION When the flexural load-carrying capacities of existing R. C. or P. C. structures are not sufficient for the service loads, structural strengthening becomes necessary. Using steel plates to strengthen concrete members is a traditional method (Raithby, 1980) and is still an important and popular way at the present time. Fiber-reinforced polymer (FRP) sheets and plates have been used recently as an alternative to steel plates for strengthening concrete structures be-cause th…     

What time-series designs may have to offer educational researchers

The promise of time-series designs for educational research and evaluation is reviewed. Ten time-series designs are presented and discussed in the context of threats to internal and external validity. The advantages and disadvantages of various visual and statistical data-analysis techniques are presented. It is argued that time-series research paradigms are useful when researchers (a) wish to involve a single subject in experimental research (individuals as units of analysis) or conduct program-evaluation studies (aggregates as units of analysis), (b) are interested in nearly continuous measurement, (c) cannot meet conventional design and statistical assumptions, or (d) wish to specify individual differences through N = 1 research strategies. It is also suggested that more research endeavors be devoted to combining unique characteristics of time-series research with conventional multi-unit paradigms.     

能量转化与守恒定律的建立

该文介绍了能量转化与守恒定律发现的背景,并以迈耳、亥姆霍兹、焦耳等重要人物为线索,论述了能 量转化与守恒定律的发现过程.     

Expression of TGF-β1 and TGF-β R II in colorectal adenomas of varying stages

To study the function of transforming growth factor β₁ (TGF-β₁) and transforming growth factor-β type II receptor (TGF-βR II) in varying stages of colorectal adenoma during neoplastic transformation, fiftyfive cases of resected colorectal adenomas were examined immunohistochemically. Our results showed that the expression of TGF-β₁ ranged from high to low, with the progression of low-grade to high-grade dysplasia of adenomas to carcinoma. And there was significantly different expression of TGF-β₁ between moderate and high dysplasia adenomas (P<0.05), but no significantly different expression of TGF-β R II was found among varying stages of adenomas. Our results suggested that the quantities of TGF-β₁ secreted by adenoma cells decrease dramatically in moderate to severe dysplasia colorectal adenomas. It is the decreased secretion of TGF-β₁, rather than the mutated TGF-βR II that may play an important role in transforming colorectal adenomas to adenocarcinomas.     

Numerical Modeling of the Performance of R22 and R290 in Adiabatic Capillary Tubes Considering Metastable Two-Phase Region--Flow Characteristics and Parametric Analysis of R22 and R290

Characteristics of R22 and its new alternative refrigerant R290 flowing through adiabatic capillary tubes are investigated based on the homogeneous model.Extensive flow variables along tube length such as pressure, temperature, viscosity, velocity, Reynolds number, friction factor and vapor quality etc are compared between the two fluids under the same operating condition. Two cases are considered, namely, either the same tube length or the same mass flow rate as inlet condition. The results show that the mass flow rate in the capillary tube of R290 is 40% lower than that of R22 due to the differences of physical properties between the two fluids. Further, a parametric analysis is performed and it appears that effects of geometric and thermodynamic parameters on mass flow rate of R290 are weaker than that of R22. When the condensing temperature is increased from 40 ℃ to 50 ℃, the mass flow rate for R22 is increased by 16%, while the increasing rate for R290 is 13%.     

如何通过泛读提高英语学习能力--谈谈《大学英语》的学习方法

本文主要通过简要分析泛读对我国英语学习者的重要性，重点介绍SQ3R的方式，以帮助大学生提高学习大学英语的效率。     

A comparison of sentence-learning errors in children of different achievement levels

Theoretical analyses of the multiple-choice test format suggest that a test constructor should give serious consideration to the form in which correct and incorrect alternatives are presented. In this experiment, third and fourth graders were tested for previously exposed information by multiple-choice items in which: (a) correct alternatives were stated in either verbatim or synonym form; and (b) incorrect alternatives consisted of plausible responses that were either familiar or new. Comparisons of errors and error patterns were made between high and low achieving students who had been given one of two different information-processing strategies. Based on a dual test function argument, it was concluded that synonym correct alternatives combined with plausible new responses are the most desirable of the four multiple-choice variations studied here. In particular, such items were sensitive to achievement level and strategy differences without systematically increasing students' likelihood of retaining misinformation.     

含参量积分连续的一个充分条件

研究了含参量积分的连续性的问题，利用一致（R）可积的定义，给出了一个新的可积充分条件，推广了通常的连续性条件．     

Locus of control, academic achievement, and Follow Through in Appalachia

The present study explored the development of locus of control in rural Appalachian Follow Through participants and in lower and middle-class comparison groups. The IAR was administered to 249 first-, third-, and sixth-grade children along with standardized achievement tests. Contrary to previous research, participation in Follow Through did not enhance internality; no social class differences were revealed. A significant social class by sex interaction was found. Strong support was not found for a developmental trend. The patterns of correlations between locus of control and achievement indicated a stronger relationship for the lower-class samples rather than for the middle-class as has been previously reported. Implications concerning different developmental antecedents in Appalachian homes as a function of sex-role socialization as well as the nature of future intervention research are discussed.     

Intestinal microflora in rats with ischemia／reperfusion liver injury

Objectives:To investigate the intestinal microflora status related to ischemia/reperfusion(I/R)liver injury and explorethe possible mechanism.Methods:Specific pathogen free grade Sprague-Dawley rats were randomized into three groups:Controlgroup(n=8),sham group(n=6)and I/R group(n=10).Rats in the control group did not receive any treatment,rats in the I/R groupwere subjected to 20 min of liver ischemia,and rats in the sham group were only subjected to sham operation.Twenty-two hourslater,the rats were sacrificed and liver enzymes and malondialdehyde(MDA),superoxide dismutase(SOD),serum endotoxin,intestinal bacterial counts,intestinal mucosal histology,bacterial translocation to mesenteric lymph nodes,liver,spleen,andkidney were studied.Results:Ischemia/reperfusion increased liver enzymes,MDA,decreased SOD,and was associated withplasma endotoxin elevation in the I/R group campared to those in the sham group.Intestinal Bifidobacteria and Lactobacillidecreased and intestinal Enterobacterium and Enterococcus