无线移动数字图书馆系统中多媒体检索的同步模式

1IntroductionRecent advances in wireless communication,digitallibrary,distributed multi media,massive storage,andmobile computing technologies are sti mulating the de-velopment of mobile multi media digital library systems(M2DLS)that allow mobile clients to access multi me-dia material anywhere and anyti me over a cellular ra-dio network[1,2].In M2DLS,multi media objects,ingeneral,can be composed of multiple media streamssuch as audio and video,whose retrieval must proceedso as to not only …     

Academic socialization,parental educational expectations,and academic self‐efficacy among Latino adolescents

This study examined the direct association between parental educational expectations and adolescents’ academic self‐efficacy, as well as the moderating influence of parental academic socialization messages. Participants were 148 Latino parent–adolescent dyads with the majority of Mexican origin (80.4%). Most of the parent participants were mothers (85.8%). Adolescents were 13 (46%) or 14 (54%) years of age, and 53% identified as female. Adolescents reported their academic self‐efficacy and perceptions of their parents’ educational expectations; parents reported on their academic socialization messages of shame/pressure and effort regarding academics. The results suggest that, after accounting for parents’ level of education and immigrant status, parental educational expectations were positively associated with adolescent academic self‐efficacy. This association was stronger among adolescents whose parents reported transmitting fewer messages of shame/pressure and academic effort. These results point to the importance of nuances in the content and type of academic socialization messages within Latino families.     

Mathematical Modeling in the Primary School: Children's Construction of a Consumer Guide

This paper examines 6th grade children's local conceptual development and mathematization processes as they worked a comprehensive mathematical modeling problem (creating a consumer guide for deciding the best snack chip) over several class periods. The children and their teachers were participating in a 3-year longitudinal teaching experiment in which sequences of mathematical modeling problems were implemented from the 5th grade (10 years of age) though to the 7th grade. In contrast to traditional problem solving, mathematical modeling requires children to generate and develop their own mathematical ideas and processes, and to form systems of relationships that are generalizable and reusable. Reported here is a detailed analysis of the iterative cycles of development of one group of children as they worked the problem, followed by a summary of the mathematization processes displayed by all groups. Children's critical reflections on their models are also reported. The results show how children can independently develop constructs and processes through meaningful problem solving. Children's development included creating systems for operationally defining constructs; selecting, categorizing, and ranking factors; quantifying quantitative and qualitative data; and transforming quantities.     

Can research on science learning and instruction inform standards for science education?

We contrast the current science education reform effort with the reforms of the 1960s and suggest how the current effort could be enhanced. We identify insights from recent research that we believe can inform the reform process, in particular, to reach all science students and also impart a cohesive view of science. We propose an alternative models view of scientific explanation and show how this view would contribute to reforms of (1) course goals, (2) social aspects of science learning, (3) instructional practices, and (4) roles for technology.This paper summarizes discussions and debates that the authors have had over the last few years. The dialogue stems, in part, from our joint participation in the American Educational Research Association Special Interest Group on Education in Science and Technology (AERA SIG:EST) leadership. This paper communicates the spirit of our thinking and does not necessarily reflect the view of SIG:EST, or any other organization.We gratefully acknowledge the support of National Science Foundation Grant MDR-9253462 in work related to this paper. We appreciate helpful comments from Eileen Lewis and the Computer as Learning Partner group.This material is based upon research supported by the National Science Foundation under grant RED-9155744. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and not necessarily reflect the views of the National Science Foundation.     

Familial patterns of learning disabilities

Extended families of 12 young adults (9 LD, 3 non-LD) were given a battery of tests and questionnaires, and 131 persons, ranging in age from 6 to 85, were classified as LD or non-LD on the basis of subtest scores 1 SD below the mean or less on subtests of the PIAT and WRAT achievement tests. Pedigree analysis indicated that LD was strongly familial, with the most probable mode involving a major gene effect, but the type of disability (reading/ math) was not directly inherited. Autoimmune disorders were significantly correlated (P<.005) with LD, especially in families in which LD remained a major handicap into adulthood, a trait that also varied between families. In two of the LD families, adults showed little evidence of the reading/spelling deficits they had shown when tested as children, while adults in other families failed to make gains in reading and spelling.     

Classroom observation systems in context: A case for the validation of observation systems

Educational Assessment, Evaluation and Accountability - Researchers and practitioners sometimes presume that using a previously “validated” instrument will produce “valid”...