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81.
Changes in students' achievement values in mathematics and reading were examined in a sample of children and early adolescents. Hierarchical linear modeling techniques were used to account for both classroom- and student-level effects. At the student level, positive changes in students' achievement values were associated positively with self-concept of ability and the previous year's achievement values in both reading and math. Measures of teachers' mastery- and performance-oriented instructional practices were included in the full HLM model. Students experienced decrements in achievement values, after controlling for other student and classroom-level variables, in classrooms where performance-oriented instructional practices were used. In the full model, self-concept of ability was related positively to increases in achievement values, whereas gender was unrelated to changes in achievement values. Copyright 2001 Academic Press.  相似文献   
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This study addresses the communication apprehension of the non‐native English speaker in the U.S. Previous studies which have examined the implications of communication apprehension (CA) for bilingual, non‐native communicators have generated results which indicate that trait‐like CA is consistent across first and second language‐speaking situations. However, none of these studies have probed the cause of the cross‐linguistic consistency of CA. This research is designed to provide a scientific explanation for the etiology of CA by applying the communibiological paradigm to CA theory and research. By selecting the situational constraints of international students, this study tests a theory based on proposition 4 of the communibiological paradigm (Beatty & McCroskey w/Valencic, 2001, p. 128): “Environment or ‘situation’ has only a negligible effect on interpersonal behavior.” The results of this study replicate the strong relationship previously observed between CA in a first language and CA in a second language. It also found that the genetic markers employed (Eysenck's Big 3 temperament variables) predicted first and second language CA approximately equally. The results indicate that, although both first and second languages are learned, the CA associated with them most likely is not.  相似文献   
85.
Korean students have shown relatively little interest and confidence in learning science, despite being ranked in the top percentile in international evaluations of academic achievement in science such as the Trends in International Mathematics and Science Study. Although research indicates a positive relationship between student perceptions of science and their science learning, this area has not been sufficiently explored in Korea. Particularly, even though both students' perceptions of scientific practice and their understanding of the nature of science (NOS) are influenced by their science learning experiences at schools, little research examines how this perception, understanding, and experience are related to one another. This study aimed to uncover Korean students' perceptions of school scientific practice through exploring their drawings, writings, and responses to questionnaires. Participants were 500 Korean students in 3rd, 7th, and 10th grades who were asked to complete an open-ended questionnaire. The results indicated that Korean students typically viewed school scientific practices as experimental activities or listening to lecture; and that most participants held an insufficient understanding of the NOS. Overall, no significant relationship emerged between students' perceptions of school scientific practice and their understanding of the NOS. Our findings highlight the need to help both teachers and students understand the potential breadth of school scientific practices, beyond simple ‘activity mania.’ This study also suggests that teachers must balance implicit and explicit instructional approaches to teaching about the NOS through scientific practices in school science contexts.  相似文献   
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While there has been a remarkable worldwide convergence in the emphases of primary science curricula over the last four decades, the cognitive and knowledge demands that they make on learners have not been well-researched. Without knowing what these intellectual or epistemic requirements are when learning science in school, issues concerning curricular alignment and access to abstract disciplinary knowledge are also likely to occur. To highlight the value of such forms of analyses, we examine the intended primary science curricula from Korea and Singapore using revised Bloom's taxonomy, as well as describe some of their general features for teaching. The results contribute insights into the complexities of the science curriculum among two similar yet different educational systems that have performed well in international science achievement tests at primary levels.  相似文献   
87.
According to the national survey of science education, science educators in the USA currently face many challenges such as lack of qualified secondary Earth and Space Science (ESS) teachers. Less qualified teachers may have difficulty teaching ESS because of a lack of conceptual understanding, which leads to diminished confidence in content knowledge. More importantly, teachers’ limited conceptual understanding of the core ideas automatically leads to a lack of pedagogical content knowledge. This mixed methods study aims to explore the ways in which current secondary schooling, especially the small numbers of highly qualified ESS teachers in the USA, might influence students’ learning of the discipline. To gain a better understanding of the current conditions of ESS education in secondary schools, in the first phase, we qualitatively examined a sample middle and high school ESS textbook to explore how the big ideas of ESS, particularly geological time, are represented. In the second phase, we quantitatively analyzed the participating college students’ conceptual understanding of geological time by comparing those who had said they had had secondary school ESS learning experience with those who did not. Additionally, college students’ perceptions on learning and teaching ESS are discussed. Findings from both the qualitative and quantitative phases indicate participating students’ ESS learning experience in their secondary schools seemed to have limited or little influence on their conceptual understandings of the discipline. We believe that these results reflect the current ESS education status, connected with the declining numbers of highly qualified ESS teachers in secondary schools.  相似文献   
88.
Associative classification methods have been recently applied to various categorization tasks due to its simplicity and high accuracy. To improve the coverage for test documents and to raise classification accuracy, some associative classifiers generate a huge number of association rules during the mining step. We present two algorithms to increase the computational efficiency of associative classification: one to store rules very efficiently, and the other to increase the speed of rule matching, using all of the generated rules. Empirical results using three large-scale text collections demonstrate that the proposed algorithms increase the feasibility of applying associative classification to large-scale problems.  相似文献   
89.
An emulsion system was simulated under simple shear rates to analyze its rheological characteristics using a hierarchical multi-scale approach. The molecular dynamics (MD) simulation was used to describe the interface of droplets in an emulsion. The equations derived from the MD simulation relative to interfacial tension, temperature, and surfactant concentration were applied as input parameters within lattice Boltzmann method (LBM) calculations. In the LBM simulation, we calculated the relative viscosity of an emulsion under a simple shear rate along with changes in temperature, shear rate, and surfactant concentration. The equations from the MD simulation showed that the interfacial tension of the droplets tended to decrease with an increase in temperature and surfactant concentration. The relative viscosity from the LBM simulation decreased with an increase in temperature. The shear thinning phenomena explaining the inverse proportion between shear rate and viscosity were observed. An increase in the surfactant concentration caused an increase in the relative viscosity for a decane-in-water emulsion, because the increased deformation caused by the decreased interfacial tension significantly influenced the wall shear stress.  相似文献   
90.
Inertial microfluidics is an emerging class of technologies developed to separate circulating tumor cells (CTCs). However, defining design parameters and flow conditions for optimal operation remains nondeterministic due to incomplete understanding of the mechanics, which has led to challenges in designing efficient systems. Here, we perform a parametric study of the inertial focusing effects observed in low aspect ratio curvilinear microchannels and utilize the results to demonstrate the isolation of CTCs with high purity. First, we systematically vary parameters including the channel height, width, and radius of curvature over a wide range of flow velocities to analyze its effect on size dependent differential focusing and migration behaviors of binary (10 μm and 20 μm) particles. Second, we use these results to identify optimal flow regimes to achieve maximum separation in various channel configurations and establish design guidelines to readily provide information for developing spiral channels tailored to potentially arbitrary flow conditions that yield a desired equilibrium position for optimal size based CTC separation. Finally, we describe a fully integrated, sheath-less cascaded spiral microfluidic device to continuously isolate CTCs. Human breast cancer epithelial cells were successfully extracted from leukocytes, achieving 86.76% recovery, 97.91% depletion rate, and sustaining high viability upon collection to demonstrate the versatility of the device. Importantly, this device was designed without the cumbersome trail-and-error optimization process that has hindered the development of designing such inertial microfluidic systems.  相似文献   
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