Antiviral activities of extracts from Hong Kong seaweeds     

Engchoon Vincent OOI  Put O. ANG Jr. 《Journal of Zhejiang University. Science. B》2008,9(12):969-976

We extracted six Hong Kong brown seaweed species with hot water for their antiviral properties. The cytotoxicity and antiviral activity of these extracts were tested by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenlytetrezolium bromide] method, cytopathic effect reduction assay, and plaque reduction assay. The antiviral effect was further determined by flow cytometric analysis. The results showed that most of these extracts inhibited the propagation of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) standard strains with very low cytotoxicity to the host cells. The extracts ofHydroclathrus clathratus and Lobophora variegata showed more potential anti-HSV activities than the extracts of the other four seaweeds. They also had moderate anti-respiratory syncytial virus (RSV) activities but could not inhibit influenza A virus. Hydroclathrus clathratus was further extracted by diluted acid and alkali and the antiviral effects of the extracts were also detected. The result showed that the hot water extract contained the main carbohydrate components that exhibited the antiviral activities against various strains of HSV, including the acyclovir-resistant strain. HI-3, a compound fractionated from this hot water extract, showed a dose-dependent anti-HSV activity in flow cytometric analysis and plaque reduction assay.  相似文献   

Conceptions of Science Teacher Mentoring and Mentoring Practice in an Alternative Certification Program     

Thomas R. Koballa Jr.  Leslie Upson Bradbury  Shawn M. Glynn  Cynthia Minchew Deaton 《Journal of Science Teacher Education》2008,19(4):391-411

Conceptions of mentoring held by six mentors and six beginning science teachers in an alternative certification program were explored qualitatively by means of case studies and phenomenography. Interviews with the six mentors and six beginning teachers produced 379 statements that were grouped into six conceptual categories. The categories of apprenticeship, personal support, and colearning revealed the variation in how mentors and beginning teachers conceptualized school-based mentoring. The conceptions functioned as referents for their mentoring practice. Mentoring as apprenticeship was the dominant conception among both the beginning teachers and mentors. The findings of this study imply that conceptions of mentoring held by mentors and beginning science teachers should be considered when organizing the school-based component of alternative certification programs.  相似文献   

Ecological Factors in Human Development          下载免费PDF全文

William E. Cross Jr. 《Child development》2017,88(3):767-769

Urie Bronfenbrenner (1992) helped developmental psychologists comprehend and define “context” as a rich, thick multidimensional construct. His ecological systems theory consists of five layers, and within each layer are developmental processes unique to each layer. The four articles in this section limit the exploration of context to the three innermost systems: the individual plus micro‐ and macrolayers. Rather than examine both the physical features and processes, the articles tend to focus solely on processes associated with a niche. Processes explored include social identity development, social network dynamics, peer influences, and school‐based friendship patterns. The works tend to extend the generalization of extant theory to the developmental experience of various minority group experiences.  相似文献   

Measuring approaches to learning in preschoolers: validating the structure of an instrument for teachers and parents     

Otilia C. Barbu  Ronald W. Marx  David B. Yaden Jr.  Deborah Levine-Donnerstein 《Education 3-13》2016,44(6):698-714

This study examined a 13-item instrument measuring approaches to learning (AtL) as a component of school readiness in the context of early childhood socio-emotional development. Few instruments, limited to preschool teacher ratings, measure AtL among kindergarteners with short easy-to-use questionnaires. We investigated psychometric properties of the instrument designed to provide practical measures of AtL behaviours identified in the Arizona Early Learning Standards with teacher (n?=?205) and guardian (n?=?1025) samples. We found a one-factor structure via exploratory factor analysis and confirmatory factor analysis (CFA). The multi-group CFA for combined teacher and guardian models indicated a good fit, which demonstrated the structure validity of the AtL instrument. This finding, combined with evidence of reliability of the instrument, supported the educational utility of the AtL as a new tool for measuring school readiness among kindergarteners in Arizona.  相似文献   

A study of the “environments” of Japanese universities     

James M. Richards Jr. 《Research in higher education》1973,1(1):87-99

A limitation of most past studies of university environments is that they have been restricted to institutions in the United States. Accordingly, as a first step in providing a broader context for such studies, this study applied two approaches to the measurement of environments to 124 Japanese universities: factor analysis of statistical data and classification of faculties according to Holland's personality typology. Both procedures yielded a reasonably clear and meaningful pattern of results that was generally similar to the pattern of results in the United States, but with differences that appear related to the organization of higher education in Japan. More generally, the results tend to support the conclusions that size, wealth, and technical emphasis are key dimensions for describing universities, and that an organization can be measured through a census of its personality types.  相似文献   

超级英雄     

Nathaniel Bronner  菜菜 《英语辅导》2008,(8)

年纪还很小的时候,我在一家药店工作。由于工作时间长,活儿也累,所以我非常珍惜午休时间,因为每到那个时候我就可以看很多漫画书。超人、蝙蝠侠、蜘蛛侠和钢铁侠都是我的英雄。  相似文献   

Examining Rater Errors in the Assessment of Written Composition With a Many-Faceted Rasch Model   总被引：2，自引：0，他引：2  

George Engelhard  Jr 《Journal of Educational Measurement》1994,31(2):93-112

This study describes several categories of rater errors (rater severity, halo effect, central tendency, and restriction of range). Criteria are presented for evaluating the quality of ratings based on a many-faceted Rasch measurement (FACETS) model for analyzing judgments. A random sample of 264 compositions rated by 15 raters and a validity committee from the 1990 administration of the Eighth Grade Writing Test in Georgia is used to illustrate the model. The data suggest that there are significant differences in rater severity. Evidence of a halo effect is found for two raters who appear to be rating the compositions holistically rather than analytically. Approximately 80% of the ratings are in the two middle categories of the rating scale, indicating that the error of central tendency is present. Restriction of range is evident when the unadjusted raw score distribution is examined, although this rater error is less evident when adjusted estimates of writing competence are used  相似文献   

Genetic Influences on Perceptions of Childhood Family Environment: A Reared Apart Twin Study     

Yoon-Mi Hur  Thomas J. Bouchard Jr. 《Child development》1995,66(2):330-345

This study estimates the extent to which heredity influences perceptions of childhood family environment in a sample of 58 monozygotic and 46 dizygotic pairs of adult twins who were reared apart. The measures used to assess family environments were the Family Environment Scale (FES) and Block Environmental Questionnaire (BEQ). A principal component factor analysis with a VARIMAX rotation of the FES and BEQ yielded 2 major factors—Support, and Organization and Cultural Orientation. Single and multiple indicator model-fitting techniques were applied to the reared apart twin data on the 2 factors. Perceived support in childhood family environments was fitted best by a model incorporating additive genetic and unshared environmental factors. Perceived organization was fitted most adequately by a model which includes only unshared environmental factors. Maximum-likelihood estimates of heritability from model-fitting analyses suggest that genetic factors explain 44% of the variance of perceptions of support dimension in childhood family environments.  相似文献   

International demand for American higher education: An extension     

Dr. J. Wilson Mixon Jr.  Weidong Wan 《Research in higher education》1990,31(2):129-134

This article reports the estimated effects of a country's population and income on its citizens' demand for American higher education. Data are from 1978, 1982, and 1987. With the behavioral variables, the model includes binary variables for Organization of Petroleum Exporting Countries (OPEC) and Asian countries. Population significantly affects demand, but the effect is not proportional: A 10% increase in population causes demand for American higher education to rise by about 2%. The impact of income is similar; for this variable, the estimated elasticity is about 0.1. Together, these findings suggest that countries meet the majority of any change in their citizens' demand with domestic supply. For 1978 and 1982, OPEC provided considerably more students than other countries, other things being equal. By 1987. This difference had vanished. At the same time, Asian countries were providing more students than other countries, other things being equal, and the difference increased monotonically through time.  相似文献   

Examining Drivers of Course Performance: An Exploratory Examination of an Introductory CIS Applications Course     

Rhonda A. Syler  Casey G. Cegielski  Sharon L. Oswald  R. Kelly Rainer  Jr. 《Decision Sciences Journal of Innovative Education》2006,4(1):51-65

The accelerating diffusion of broadband Internet access provides many opportunities for the development of pedagogically robust Web‐based instruction (WBI). While the supporting technology infrastructure of broadband disseminates, the attention of academic researchers focuses upon issues such as the drivers of student usage of WBI. Specifically, the research presented herein examined the impact of WBI on a student's aggregate course performance. We hypothesized that learning independence (LI) is a determinate factor in a student's use of WBI. In this study, we employed structural equation modeling techniques to examine the data and assess the direct and indirect effects of LI on WBI usage. The subjects, students in an introductory Computer Information Systems applications course, used a Web‐based tutorial program for skills instruction. The findings of this study suggest that WBI usage has a significant impact on a student's course performance. Despite its plausibility, the effect of LI on WBI usage was not significant. However, we did conclude that two of the second order factors of the LI construct have a direct effect on a student's performance in the course.  相似文献