Zusammenfassung. Wir pr?sentieren in dieser Arbeit das ObjectGlobe-System, ein offenes und verteiltes Anfragebearbeitungssystem auf Internet-Datenquellen.
ObjectGlobe erweitert die begrenzten F?higkeiten des Internets bezüglich Anfragebearbeitung, indem es einen offenen Marktplatz
schafft, in dem eine Vielzahl von Anbietern Rechenzeit, Daten und Anfrageoperatoren bereitstellen. Den Schwerpunkt dieses
Beitrags bildet die im Rahmen des ObjectGlobe-Projekts entwickelte Metadatenverwaltung MDV, ein verteiltes Metadaten-Management-System.
Es besitzt eine 3-schichtige Architektur und unterstützt Caching und Replikation in der Mittelschicht, so dass Anfragen lokal
ausgewertet werden k?nnen. Benutzer spezifizieren die Informationen, die sie ben?tigen und die repliziert werden, mit Hilfe
einer besonderen Regelsprache. Um Replikate aktuell zu halten und die Replikation von neuen und relevanten Informationen anzusto?en,
verwendet das MDV-System einen neuartigen Publish & Subscribe-Algorithmus. Wir beschreiben diesen Algorithmus im Detail und
zeigen, wie er mit Hilfe eines normalen relationalen Datenbanksystems implementiert werden kann.
Eingegangen am 19. November 2001 / Angenommen am 30. Juli 2002 相似文献
Educational technology research and development - Authentic project-based learning (APBL) is a highly effective way for instructors to help students learn disciplinary skills, modes of thinking,... 相似文献
This paper presents empirical evidence on the adoption, implementation and the perceived effectiveness of quality management in teaching and learning in German higher education institutions. Theoretically, the article combines two new institutionalist approaches: institutional isomorphism and institutional entrepreneurship. Empirically, the study refers to qualitative interview data and quantitative survey data. The analysis reveals that isomorphism is a leading driver behind the adoption of quality management in German higher education institutions, whereas institutional entrepreneurship plays an important role in quality management implementation. While isomorphism can be regarded as a conclusive reason behind the absence of a perception of quality management’s effectiveness, institutional entrepreneurship may function as a corrective towards the overall negative impact of isomorphic conformity by institutionalizing quality management in a sustainable manner.
This study examined the psychometric properties of the Sexual Orientation Counselor Competency Scale (SOCCS), an instrument that measures the attitudes, skills, and knowledge of counselors who work with lesbian, gay, and bisexual individuals. Internal consistency of the SOCCS was .90, and 1‐week test‐retest reliability was .84. Criterion, concurrent, and divergent validity tests established the SOCCS as a psychometrically sound instrument. 相似文献
Instructional Science - Extensive research has established that successful learning from an example is conditional on an important learning activity: self-explanation. Moreover, a model for... 相似文献
Decades of research produced inconsistent findings on whether study time can lead to achievement gains in mathematics. Data generated by more than six thousand students from three different countries who solved more than 1.1 million problem sets using a dedicated mathematics software are analyzed regarding the effect of study time on students’ achievements in mathematics. Results showed that more study time led to higher performance scores in mathematics. Further analyses revealed that low-performing students in the first school year (2017-2018) who increased their study time in the following year (2018-2019) revealed greatest gains in performance in the same school year (2018-2019) and even in the year after (2019-2020). Finally, results replicated previous observations of robust performance scores within students over the three school years, with performance scores in 2017-2018 predicting those of 2018-2019 which predicted those of 2019-2020. These results support the idea that students, in particular low-performing students, can boost their academic abilities to upper levels when increasing their study time.
Learning that takes place outside the formal classroom, called informal learning, has been a difficult parameter to assess due to the heterogeneous nature of the subjects and everyday learning situations. To date, no instrument has been developed to effectively examine the wide variety of informal experiences a child may encounter. Central to this study was the development and field testing of such an instrument, the Informal Learning Opportunities Assay (ILOA). The ILOA was administered to a total of 2128 middle and high school students and was found to be ethnically neutral, easily scored, and flexible in design to accommodate practitioners and researchers. The instrument was found to provide a reliable assessment of informal learning opportunities. 相似文献
This study investigated the effects of three instructional conditions on precursors to successful reading for Spanish‐speaking English language learners (ELL). The study was conducted using a randomized, alternate treatment control group design specifically targeting phonological awareness (PA) listening comprehension (LC), and decoding in a sample of ELL (N= 82) including students who were and were not at risk for later reading failure. Two randomly assigned experimental intervention groups and one treatment control group were created to test the effectiveness of three instructional interventions that differed in the relative amount of time used for instructing the word‐ and text‐level targeted skills. Specifically, the two experimental intervention groups received different doses of LC relative to PA instruction, creating a LC Concentration group and a PA Concentration group. The treatment control group received only PA and alphabet knowledge instruction (word‐level skills). Results indicated that both at‐risk and not‐at‐risk ELLs in the LC Concentration group outperformed students in the other groups on almost all measures, including PA skills, despite minimal amounts of instructional time‐targeting word‐level skills. These data extend the existing literature by lending empirical support to the use of a LC component in early reading interventions for young ELL. 相似文献
It has been shown (Lawrence, S. (2001). Online or invisible? Nature, 411, 521) that journal articles which have been posted without charge on the internet are more heavily cited than those which have not been. Using data from the NASA Astrophysics Data System (ads.harvard.edu) and from the ArXiv e-print archive at Cornell University (arXiv.org) we examine the causes of this effect. 相似文献
We examined (1) the prevalence of childhood sexual abuse (CSA) experiences as a function of cohort and gender, (2) the prevalence of factors associated with CSA as a function of cohort and whether the association of these factors with CSA remained the same irrespective of cohort, and (3) whether any cohort differences could be explainable by cohort differences in reporting bias.
Method
We used the responses of 4,561 men (M = 29, SD = 7 years) and 8,361 female (M = 29, SD = 7 years) Finnish participants who responded to the Childhood Trauma Questionnaire-Short Form as well as questions regarding family structure.
Results
The prevalence of CSA experiences varied between 0.7-4.6% for men and 1.8-7.5% for women depending on the item. Younger cohorts reported less CSA as well as less of the risk factors (physical neglect and abuse, emotional neglect and abuse, parental substances abuse, not growing up with both biological parents) that were positively associated with the likelihood of CSA. The effects of these risk factors did not vary as a function of the cohort. Also, the declining trend was not explainable by social desirability being higher in the younger cohorts.
Conclusions
The results suggest that there is a real decline in the prevalence of CSA and it is associated with a simultaneous decline in factors associated with CSA. 相似文献
