Browsing by Author "Wu, YT"

Now showing 1 - 9 of 9

A new quorum-based replica control protocol
(1997)
Wu, YT
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Chang, YJ
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Yuan, SM
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Chang, HK
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資訊工程學系
Data replication if an important issue in distributed systems. Many protocols are designed to achieve high availability, but some of them have restrictions on N, the number of nodes in the system. This motivates us to design a protocol suitable for arbitrary N. In this paper, we present a new quorum-based replica control protocol whose quorum size is O(root N), which is the same as that of the grid protocol. Moreover; the proposed protocol is almost symmetric, i.e., each node nearly bears the same responsibility. In particular, our protocol performs well in systems where read operations are requested more frequently than write ones.
Development of elementary school students' cognitive structures and information processing strategies under long-term constructivist-oriented science instruction
(2005-09-01)
Wu, YT
;
Tsai, CC
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教育研究所
;
師資培育中心
;
Institute of Education
The main purpose of this study was to explore the effects of long-term constructivist-oriented science instruction on elementary school students' process of constructing cognitive structures. Furthermore, such effects on different science achievers were also investigated. The subjects of this study were 69 fifth graders in Taiwan, while they were assigned to either a constructivist-oriented instruction group or a traditional teaching group. The research treatment was conducted for 5 months, including six instructional units, and students' cognitive structures were probed through interviews coupled with a "metalistening technique" after the instruction of each unit. The interview narratives were transcribed into the format of "flow maps." In addition, the information processing modes shown in the flow maps were also investigated through a series of content analyses. The findings showed that the students in the constructivist-oriented instruction group attained significantly better learning outcomes in terms of the extent and integration of their cognitive structures, metacognition engagement, and the usage of information processing strategies. Moreover, it was also revealed that both high achievers and low achievers benefited from the constructivist-oriented instructional activities, but in different ways. For example, both high achievers and low achievers in the constructivist-oriented instruction group attained better usage of information processing strategies than their counterparts in traditional teaching group did; but only high achievers displayed better usage of higher order information processing modes (i.e., inferring or explaining) than their counterparts in traditional teaching group did. The results in this study finally suggest a four-stage model for students' process of constructing cognitive structure under the constructivist-oriented science instruction, including "cognitive structure acquisition," "metacognition enrichment," "cognitive structure integration," and "cognitive structure refinement." (c) 2005 Wiley Periodicals, Inc.
Discovery of different types of inhibition between the human and Thermotoga maritima alpha-fucosidases by fuconojirimycin-based derivatives
(2006-05-09)
Ho, CW
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Lin, YN
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Chang, CF
;
Li, ST
;
Wu, YT
An efficient method for examining the selectivity of inhibitors on two alpha-fucosidases, one from Thermotoga maritima and the other from human, was established. The X-ray crystal structure of the former enzyme makes possible the homology modeling of the human alpha-fucosidase, indicating the major difference between both enzymes in the periphery of the catalytic site. To investigate the difference at the molecular level, a variety of fuconojirimycin (FNJ) derivatives with substitution at Cl, C2, C6, or N were rapidly prepared in microplates and screened without purification for the inhibition activities of the two alpha-fucosidases. Among the molecules that were tested, only the substitution at Cl can significantly enhance the inhibitory potency, in contrast to the control (no substitution) and compounds with substitution at other positions. The majority of Cl-substituted FNJs were found to be slow tight-binding inhibitors of the Thermotoga enzyme, while acting as the reversible inhibitors of the human fucosidase. The best inhibitor exhibited 13700-fold difference in affinity between the two enzymes, which was attributed to the dissimilar aglycon binding site. Further investigations were carried out, including site-directed mutagenesis, the comparison of K-i values among the wild type and mutants, and the intrinsic fluorescence change upon inhibitor titration, all supporting the idea that Tyr64 and Tyr267 of the Thermotoga alpha-fucosidase are critically involved in closely interacting with the aglycon of inhibitors. The increased level of contact thus induced conformational change, leading to the observed slow tight-binding inhibition.
Effects of constructivist-oriented instruction on elementary school students' cognitive structures
(2005-06-01)
Wu, YT
;
Tsai, CC
;
教育研究所
;
師資培育中心
;
Institute of Education
The purpose of this study was primarily to explore the effects of constructivist-oriented instruction on fifth graders' cognitive structures about biological reproduction. Furthermore, such effects on different science achievers were also investigated. The subjects of this study were 69 eleven year olds in Taiwan, who were assigned to either a constructivist-oriented instruction group or a traditional teaching group. The research treatment was conducted for three weeks, and the interview data were gathered a week later after the instruction about biological reproduction. The interview narratives were transcribed into 'flow maps'. The information processing modes shown in the flow maps were also investigated through a series of content analysis. The results of this study revealed that students in the constructivist-oriented instruction group, in general, attained better learning outcomes about biological reproduction after instruction, both in terms of the extent of concepts and in the richness within their cognitive structures. Furthermore, the students in this group were probably better organised and stored their ideas in a higher-level mode of information processing, especially in the mode of 'inferring or explaining'. However, high achievers and low achievers in the constructivist-oriented instruction attained better usage of information processing modes in somewhat different ways; only high achievers in the constructivist-oriented instruction group attained significantly better usage of high-order information processing modes.
ICA-based spatiotemporal approach for single-trial analysis of postmovement MEG beta synchronization
(2003-12-01)
Lee, PL
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Wu, YT
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Chen, LF
;
Chen, YS
;
Cheng, CM
The extraction of event-related oscillatory neuromagnetic activities from single-trial measurement is challenging due to the non-phase-locked nature and variability from trial to trial. The present study presents a method based on independent component analysis (ICA) and the use of a template-based correlation approach to extract Rolandic beta rhythm from magnetoencephalographic (MEG) measurements of right finger lifting. A single trial recording was decomposed into a set of coupled temporal independent components and corresponding spatial maps using ICA and the reactive beta frequency band for each trial identified using a two-spectrum comparison between the postmovement interval and a reference period. Task-related components survived dual criteria of high correlation with both the temporal and the spatial templates with an acceptance rate of about 80%. Phase and amplitude information for noise-free MEG beta activities were preserved not only for optimal calculation of beta rebound (event-related synchronization) but also for profound penetration into subtle dynamics across trials. Given the high signal-to-noise ratio (SNR) of this method, various methods of source estimation were used on reconstructed single-trial data and the source loci coherently anchored in the vicinity of the primary motor area. This method promises the possibility of a window into the intricate brain dynamics of motor control mechanisms and the cortical pathophysiology of movement disorder on a trial-by-trial basis. (C) 2003 Elsevier Inc. All rights reserved.
Information commitments: evaluative standards and information searching strategies in web-based learning environments
(2005-10-01)
Wu, YT
;
Tsai, CC
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教育研究所
;
師資培育中心
;
Institute of Education
'Information commitments' include both a set of evaluative standards that Web users utilize to assess the accuracy and usefulness of information in Web-based learning environments (implicit component), and the information searching strategies that Web users use on the Internet (explicit component). An 'Information Commitment Survey' (ICS), consisting of aforementioned components, was developed. The participants of this study were 610 university students, coming from four universities in Taiwan, and their information commitments were surveyed. Through a series of structural equation modelling (SEM) analyses with Linear Structure RELationships (LISREL), this study confirmed the reliability and validity of ICS. More importantly, the causal relationships between the two components of ICS were also examined. The findings showed that learners' evaluative standards on Web materials (implicit component) had significant effects on their information searching strategies in Web-based learning environments (explicit component). For example, learners who utilized an advanced evaluative standard, such as using multiple sources to judge the accuracy of Web materials, were significantly more oriented toward using a sophisticated information searching strategy, such as carefully exploring and elaborating information in Web-based learning environments. In other words, learners' evaluative standards for Web materials should be viewed as important predictors for their searching strategies in Web-based learning environments.
Modeling and simulation of motorcycle traffic flow
(2004)
Cho, HJ
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Wu, YT
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
Mixed-traffic that contains motorized and nonmotorized vehicles become more common in urban areas. Compare with motorized traffic, nonmotorized traffic flow theory isn't mature enough. In this study, a motorcycle traffic flow model is proposed It contains longitudinal and lateral movement models. The motorcycle traffic flow is influenced by driver characteristics, vehicle interactions, and the external environment all of which the proposed model will take into account. Finally, a motorcycle traffic flow simulation is presented. The simulation result indicates that the proposed model is reasonable, and it can reflect some motorcycle traffic flow phenomena The behaviors of bicycles and pedestrians are similar to motorcycles; the result of this study could be the basis of bicycle or pedestrian flow model.
Sheathless capillary electrophoresis/electrospray ionization mass spectrometry using a pulled bare fused-silica capillary as the electrospray emitter
(2005-04-01)
Wu, YT
;
Chen, YC
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應用化學系
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Department of Applied Chemistry
It has always been assumed that electrical contact at the capillary outlet is a necessary requirement when coupling capillary electropboresis (CE) with electrospray ionization mass spectrometry (ESI-MS). In this study, we used a pulled bare-capillary tip as the ESI emitter, but neither was it coated with any electrically conductive materials nor was a high external voltage applied on its outlet. In this paper, we demonstrate that this straightforward approach may be used to generate multiply charged ions of proteins and peptides through electrospray ionization. Our results indicate that peptides and proteins, including bradykinin, cytochrome c, myoglobin, and tryptic digest products that elute from a pulled bare-capillary tip can be detected directly by ESI-MS using the tapered bare-capillary interface. Thus, we have demonstrated that CE and ESI-MS may be combined successfully without the need to modify the outlet of the capillary tip with an electrically contacting material.
University students' self-efficacy and their attitudes toward the Internet: the role of students' perceptions of the Internet
(2006-03-01)
Peng, HY
;
Tsai, CC
;
Wu, YT
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教育研究所
;
師資培育中心
The attitudes and the self-efficacy that characterize learners relative to the Internet have been identified as important factors that affect learners' motivation, interests and performance in Internet-based learning environments. Meanwhile, learners' perceptions of the Internet may shape learners' attitudes and online behaviours. This study investigates university students' attitudes and self-efficacy towards the Internet, and explores the role that university students' perceptions of the Internet may play in their Internet attitudes and self-efficacy. The results indicate that university students demonstrate positive attitudes and adequate Internet self-efficacy and that these students are more inclined to view the Internet as a functional tool - a functional technology. Gender differences exist in university students' attitudes towards, and perceptions of, the Internet; that is, male students demonstrate Internet attitudes that are more positive than those of their female peers. Furthermore, students who perceive the Internet as a leisure tool ( e. g. as a tour or a toy) show more positive attitudes and communicative self-efficacy than students who use the Internet as a functional technology. Educators and researchers need to be aware of these differences and to take them into consideration in their instruction. Lastly, this study serves as a starting-point for research that more broadly explores learners' perceptions of the Internet.