Task switching effects in anticipation timing     

Fairbrother JT  Brueckner S 《Research quarterly for exercise and sport》2008,79(1):116-121

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Information and announcements     

K. L. Sebastian 《Resonance》2017,22(11):1099-1102

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Are there differences in ethnic majority and minority adolescents’ friendships preferences and social influence with regard to their academic achievement?     

Tobias H. Stark  Lars Leszczensky  Sebastian Pink 《Zeitschrift für Erziehungswissenschaft》2017,20(3):475-498

Research has established that adolescents both befriend peers based on their academic achievement and adjust their own achievement to that of their friends’ over time. However, these processes may be different for ethnic minority students, because some of them may adhere to an oppositional culture that rejects striving for academic success. We examine respective differences between self-identified ethnic minority and majority students using longitudinal social network analysis (stochastic actor-oriented models) in a sample of 1175 students (aged 13) from 12 grade-level networks in Germany secondary schools. Among the students, we find that academically successful students in particular prefer friends with high grades, but that students with poor grades exert more social influence on their friends to adjust their performance. Moreover, while minority students are indeed less inclined to select friends with higher grades, both ethnic majority and minority youth prefer friends with similar academic achievement and are similarly influenced by their friends’ achievement. However, social influence is stronger from same-ethnic than from inter-ethnic friends. In sum, there is mixed evidence for an oppositional culture among ethnic minority students in our sample.  相似文献   

Effect of foster care on young children's language learning     

Windsor J  Benigno JP  Wing CA  Carroll PJ  Koga SF  Nelson CA  Fox NA  Zeanah CH 《Child development》2011,82(4):1040-1046

This report examines 174 young children's language outcomes in the Bucharest Early Intervention Project, the first randomized trial of foster placement after institutional care. Age of foster placement was highly correlated with language outcomes. Placement by 15 months led to similar expressive and receptive language test scores as typical age peers at 30 and 42 months. Placement from 15 to 24 months also led to dramatic language improvement. In contrast, children placed after 24 months had the same severe language delays as children in institutional care. Language samples at 42 months confirmed that placement after 24 months led to lower expressive skill.  相似文献   

Knots and links     

K. L. Sebastian 《Resonance》2006,11(3):25-35

Knots appear in a variety of contexts in physics, chemistry and biology. This article is an introduction to the science of knots and links for the uninitiated and it outlines why scientists find them fascinating.  相似文献   

Elitenrekrutierung in Frankreich und Deutschland     

Sebastian Braun  Giselher Spitzer 《Sportwissenschaft》2002,32(2):217-220

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Das MINERVA-Projekt: Datenbankselektion für Peer-to-Peer-Websuche     

Matthias Bender  Sebastian Michel  Gerhard Weikum und Christian Zimmer 《Informatik - Forschung und Entwicklung》2005,20(3):152-166

Zusammenfassung 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.

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This paper presents the MINERVA project that protoypes a distributed search engine based on P2P techniques. MINERVA is layered on top of a Chord-style overlay network and uses a powerful crawling, indexing, and search engine on every autonomous peer. We formalize our system model and identify the problem of efficiently selecting promising peers for a query as a pivotal issue. We revisit existing approaches to the database selection problem and adapt them to our system environment. Measurements are performed to compare different selection strategies using real-world data. The experiments show significant performance differences between the strategies and prove the importance of a judicious peer selection strategy. The experiments also present first evidence that a small number of carefully selected peers already provide the vast majority of all relevant results.

CR Subject Classification H.4,H.3.3,H3.4  相似文献   

Das MINERVA-Projekt: Datenbankselektion für Peer-to-Peer-Websuche     

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   

Formation of embryoid bodies using dielectrophoresis     

Agarwal S  Sebastian A  Forrester LM  Markx GH 《Biomicrofluidics》2012,6(2):24101-2410111

Embryoid body (EB) formation forms an important step in embryonic stem cell differentiation invivo. In murine embryonic stem cell (mESC) cultures EB formation is inhibited by the inclusion of leukaemic inhibitory factor (LIF) in the medium. Assembly of mESCs into aggregates by positive dielectrophoresis (DEP) in high field regions between interdigitated oppositely castellated electrodes was found to initiate EB formation. Embryoid body formation in aggregates formed with DEP occurred at a more rapid rate-in fact faster compared to conventional methods-in medium without LIF. However, EB formation also occurred in medium in which LIF was present when the cells were aggregated with DEP. The optimum characteristic size for the electrodes for EB formation with DEP was found to be 75-100 microns; aggregates smaller than this tended to merge, whilst aggregates larger than this tended to split to form multiple EBs. Experiments with ESCs in which green fluorescent protein (GFP) production was targeted to the mesodermal gene brachyury indicated that differentiation within embryoid bodies of this size may preferentially occur along the mesoderm lineage. As hematopoietic lineages during normal development derive from mesoderm, the finding points to a possible application of DEP formed EBs in the production of blood-based products from ESCs.  相似文献   

A high resolution laser scanning model of the Roman theater in Pinara,Turkey – comparison to previous measurements and search for the causes of damage     

Klaus-G. Hinzen  Stephan Schreiber  Sebastian Rosellen 《Journal of Cultural Heritage》2013,14(5):424-430

The archaeological site Pinara, southwest Turkey, which includes several remarkable objects of cultural heritage, has been the focus of several previous archaeoseismic studies. One of these examined the setting of the Roman theater in the east of Pinara by a lidar survey. A gross inclination of the stone rows of the auditorium of 0.81° towards N 314°E was interpreted as a consequence of recent coseismic tectonic movements. A new survey of the theater with a terrestrial phase laser scanner is the basis for a model with 15 times higher resolution and 28 times more data points. Parallel to the fieldwork in this study, the process and accuracy of the leveling of the 3D point clouds produced by the scanner was tested in a series of experiments. Based on the orientation of the blocks forming the seats of the theater, we suggest six sections with changing average inclination of the seats and a fault line separating a northern and a southern section. While the previously found overall inclination of the auditorium is confirmed by the new model and the dip direction agrees, the inclination is 0.58° compared to previously determined 0.81°. The almost perfect increase of inclination with the height of the first 10 entire seating rows and the nearly constant inclination from row 11 onward, makes systematic measurement errors during the construction a possible cause. This is an alternative scenario to the interpretation of a coseismic displacement of the conglomerate block on which the theater was built.  相似文献