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
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.
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
International Journal of Science and Mathematics Education - The burden placed by human activities on Earth is ever-increasing. Global environmental changes have profoundly affected the... 相似文献
We analysed the decisions of major European public funding organisations to fund or not to fund synthetic biology (SB) and related ethical, legal and social implication (ELSI) studies. We investigated the reaction of public organisations in six countries (Austria, France, Germany, the Netherlands, Switzerland and the U.K.) towards SB that may influence SB's further development in Europe. We examined R&D and ELSI communities and their particular funding situation. Our results show that the funding situation for SB varies considerably among the analysed countries, with the U.K. as the only country with an established funding scheme for R&D and ELSI that successfully integrates these research communities. Elsewhere, we determined a general lack of funding (France), difficulties in funding ELSI work (Switzerland), lack of an R&D community (Austria), too small ELSI communities (France, Switzerland, Netherlands), or difficulties in linking existing communities with available funding sources (Germany), partly due to an unclear SB definition. 相似文献
One common application of structural equation modeling (SEM) involves expressing and empirically investigating causal explanations. Nonetheless, several aspects of causal explanation that have an impact on behavioral science methodology remain poorly understood. It remains unclear whether applications of SEM should attempt to provide complete explanations or partial explanations. Moreover, it remains unclear what sorts of things researchers can best take as causes and effects. Finally, the meaning of causal assertions itself remains poorly understood. Attempting to clarify the use of structural equations as causal explanations by addressing these issues has implications for behavioral science methodology because applications of SEM typically remain vague about causation and thus about their substantive conclusions. Research aimed at clarifying these issues can lead to a sharper and more refined use of SEM for causal explanation, and by extension, clarify behavioral science methodology more generally. 相似文献
