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31.
Matthias Bender Sebastian Michel Gerhard Weikum Christian Zimmer 《Informatik - Forschung und Entwicklung》2005,12(5):152-166
In diesem Artikel wird MINERVA pr?sentiert, eine prototypische Implementierung einer verteilten Suchmaschine basierend auf
einer Peer-to-Peer (P2P)-Architektur. MINERVA setzt auf die in der P2P-Welt verbreitete Technik verteilter Hash-Tabellen auf
und benutzt diese zum Aufbau eines verteilten Verzeichnisses. Peers in unserem Ansatz entsprechen v?llig autonomen Benutzern mit ihren lokalen Suchm"oglichkeiten, die bereit sind, ihr lokales
Wissen und ihre lokalen Suchm?glichkeiten im Rahmen einer Kollaboration zur Verfügung zu stellen. Wir formalisieren unsere
Systemarchitektur und beschreiben das zentrale Problem einer effizienten Suche nach vielversprechenden Peers für eine konkrete
Anfrage innerhalb des Verbundes. Wir greifen dabei auf existierende Methoden zurück and passen diese an unseren Systemkontext
an. Wir pr?sentieren Experimente auf realen Daten, die verschiedene dieser Ans?tze vergleichen. Diese Experimente zeigen,
dass die Qualit?t der Ans?tze variiert und untermauern damit die Wichtigkeit und den Einfluss einer leistungsstarken Methode
zur Auswahl guter Datenbanken. Unsere Experimente deuten an, dass eine geringe Anzahl sorgf?ltig ausgew?hlter Datenbanken
typischerweise bereits einen Gro?teil aller relevanten Ergebnisse des Gesamtsystems liefert. 相似文献
32.
33.
Miarka B Panissa VL Julio UF Del Vecchio FB Calmet M Franchini E 《Journal of sports sciences》2012,30(9):899-905
The aim of this study was to compare time-motion indicators during judo matches performed by athletes from different age groups. The following age groups were analysed: Pre-Juvenile (13-14 years, n = 522), Juvenile (15-16 years, n = 353); Junior (19 years, n = 349) and Senior (>20 years, n = 587). The time-motion indicators included: Total Combat Time, Standing Combat Time, Displacement Without Contact, Gripping Time, Groundwork Combat Time and Pause Time. Analysis of variance (ANOVA) one-way and the Tukey test, as well as the Kruskal-Wallis test and Mann-Whitney (for non-parametric data), were conducted, using P < 0.05 as significance level. The results showed that all analysed groups obtained a median of 7 (first quantile - 3, third quantile - 12) sequences of combat/pause cycles. In total time of combat, the result was: for Total Combat Time, Standing Combat Time and Gripping Time: Pre-Juvenile and Senior were significantly longer than Juvenile and Junior. Considering Displacement Without Contact, Junior was significantly longer than all other age groups. For Groundwork Combat Time, Senior was significantly longer than all other age groups and Pre-Juvenile was longer than Junior. These results can be used to improve the physiological performance in intermittent practices, as well as technical-tactical training during judo sessions. 相似文献
34.
Schmitt KU Wider D Michel FI Brügger O Gerber H Denoth J 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(1):57-72
Wrist injuries are frequently observed after falls in snowboarding. In this study, laboratory experiments mimicking forward and backward falls were analysed. In six different falling scenarios, participants self-initiated falls from a static initial position. Eighteen volunteers conducted a total of 741 trials. Measurements were taken for basic parameters describing the kinematics as well as the biomechanical loading during impact, such as impact force, impact acceleration, and velocity. The effective mass affecting the wrist in a fall also was determined. The elbow angle at impact showed a more extended arm in backward falls compared to forward falls, whereas the wrist angle at impact remained similar in forward and backward falls. The study results suggest a new performance standard for wrist guards, indicating the following parameters to characterize an impact: an effective mass acting on one wrist of 3-5 kg, an impact angle of 75 degrees of the forearm relative to the ground, and an impact velocity of 3 m/s. 相似文献
35.
Shaul SHALVI Matthijs BAAS Michel J. J. HANDGRAAF Carsten K.W. DE DREU 《Learned Publishing》2010,23(2):117-123
At a top psychology journal, Psychological Science (PS), submissions peak during the summer months. We tested whether this seasonal submission bias decreases the likelihood of a paper being accepted in that period. Month of submission data was obtained for all 575 publications in PS for the period 2003–2006. Whereas submissions to PS were higher in the summer, there was no evidence that most accepted publications were originally submitted in the summer. Thus, contributors submit to PS when the likelihood of acceptance is the lowest – creating their own entrance barrier. A similar seasonal pattern was not identified for Personality and Social Psychology Bulletin, another top psychology journal. Using the Web of Knowledge database, we further assessed whether overcoming the seasonal entrance barrier influences the number of citations a paper receives in subsequent years. We discuss the possibility that the different rejections policies in the two journals, employing desk rejections or not, may explain this discrepancy, and explore a range of alternative hypotheses. 相似文献
36.
Michel Zitt 《Journal of Informetrics》2010,4(3):392-406
The principle of a new type of impact measure was introduced recently, called the “Audience Factor” (AF). It is a variant of the journal impact factor where emitted citations are weighted inversely to the propensity to cite of the source. In the initial design, propensity was calculated using the average length of bibliography at the source level with two options: a journal-level average or a field-level average. This citing-side normalization controls for propensity to cite, the main determinant of impact factor variability across fields. The AF maintains the variability due to exports–imports of citations across field and to growth differences. It does not account for influence chains, powerful approaches taken in the wake of Pinski–Narin's influence weights. Here we introduce a robust variant of the audience factor, trying to combine the respective advantages of the two options for calculating bibliography lengths: the classification-free scheme when the bibliography length is calculated at the individual journal level, and the robustness and avoidance of ad hoc settings when the bibliography length is averaged at the field level. The variant proposed relies on the relative neighborhood of a citing journal, regarded as its micro-field and assumed to reflect the citation behavior in this area of science. The methodology adopted allows a large range of variation of the neighborhood, reflecting the local citation network, and partly alleviates the “cross-scale” normalization issue. Citing-side normalization is a general principle which may be extended to other citation counts. 相似文献
37.
Alexandre J. S. Morin Christophe Maïano Benjamin Nagengast Herbert W. Marsh Julien Morizot Michel Janosz 《Structural equation modeling》2013,20(4):613-648
Substantively, this study investigates potential heterogeneity in the developmental trajectories of anxiety in adolescence. Methodologically, this study demonstrates the usefulness of general growth mixture analysis (GGMA) in addressing these issues and illustrates the impact of untested invariance assumptions on substantive interpretations. This study relied on data from the Montreal Adolescent Depression Development Project (MADDP), a 4-year follow-up of more than 1,000 adolescents who completed the Beck Anxiety Inventory each year. GGMA models relying on different invariance assumptions were empirically compared. Each of these models converged on a 5-class solution, but yielded different substantive results. The model with class-varying variance–covariance matrices was retained as providing a better fit to the data. These results showed that although elevated levels of anxiety might fluctuate over time, they clearly do not represent a transient phenomenon. This model was then validated in relation to multiple predictors (mostly related to school violence) and outcomes (grade-point average, school dropout, depression, loneliness, and drug-related problems). 相似文献
38.
39.
Danica G. Hays Stephanie A. Crockett Rebecca Michel 《Counselor Education & Supervision》2021,60(1):51-72
Counselor educators are well‐equipped to serve as academic leaders, yet little is known about what factors influence their engagement experiences. This grounded theory provides a theoretical model of academic leadership engagement based on interviews with 20 counselor educators with academic leadership experience. Implications for facilitating academic leadership engagement are provided. 相似文献
40.