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We analyze the impact of exercising sports during childhood and adolescence on educational attainment. The theoretical framework is based on models of allocation of time and educational productivity. Using the rich information from the German Socio-Economic Panel (GSOEP), we apply generalized ordered probit models to estimate the effect of participation in sport activities on secondary school degrees and professional degrees. Even after controlling for important variables and selection into sport, we find strong evidence that the effect of sport on educational attainment is statistically significant and positive. 相似文献
23.
Elke Achtert Christian B?hm Peer Kr?ger Peter Kunath Alexey Pryakhin Matthias Renz 《Informatik - Forschung und Entwicklung》2007,15(3):179-195
The reverse k-nearest neighbor (RkNN) problem, i.e. finding all objects in a data set the k-nearest
neighbors of which include a specified query object, has received increasing attention recently. Many
industrial and scientific applications call for solutions of the RkNN problem in arbitrary metric spaces
where the data objects are not Euclidean and only a metric distance function is given for specifying
object similarity. Usually, these applications need a solution for the generalized problem where the
value of k is not known in advance and may change from query to query. In addition, many applications
require a fast approximate answer of RkNN-queries. For these scenarios, it is important to generate
a fast answer with high recall. In this paper, we propose the first approach for efficient approximative
RkNN search in arbitrary metric spaces where the value of k is specified at query time. Our approach
uses the advantages of existing metric index structures but proposes to use an approximation of the
nearest-neighbor-distances in order to prune the search space. We show that our method scales significantly
better than existing non-approximative approaches while producing an approximation of the true query
result with a high recall. 相似文献
24.
25.
Christian Köhler 《Research Policy》2012,41(8):1344-1356
The shift toward more open and interconnected innovation activities has been a major topic in recent academic and practitioner discussions. Firms must connect their in-house R&D activities with external partners, such as leading customers or universities, to increase the effectiveness of their innovation activities. Hence, management needs to define where to search for valuable knowledge in its environment. In this paper we argue that knowledge search has to reflect the heterogeneity of various knowledge sources with regard to the knowledge they can provide and how these sources can be activated. We hypothesize that search strategies driven by science, suppliers and the product market will contribute differently to innovation success with new-to-market versus imitated products. Moreover, we explore the effect of these types of knowledge search within different sectoral patterns of innovation. Our empirical analysis rests on a sample of almost 5000 firms from five Western European countries. The results support our hypotheses and highlight the potentials and shortcomings of different types of knowledge search. 相似文献
26.
Stephan Sorichter Johannes Mair Arnold Koller Erich Muller Christian Kremser Werner Judmaier 《Journal of sports sciences》2013,31(9):687-691
The aim of this study was to examine the relationship between myosin heavy chain (MHC) release as a specific marker of slow-twitch muscle fibre breakdown and magnetic resonance imaging (MRI) of skeletal muscle injury after eccentric exercise. The effects of a single series of 70 high-intensity eccentric contractions of the quadriceps femoris muscle group (single leg) on plasma concentrations of creatine kinase and MHC fragments were assessed in 10 young male sport education trainees before and 1 and 4 days after exercise. To visualize muscle injury, MRI of the loaded thigh was performed before and 4 days after the eccentric exercise. All participants recorded an increase ( P ? 0.05) in creatine kinase after exercise. In five participants, T2 signal intensity was unchanged post-exercise compared with pre-exercise and MHC plasma concentration was normal; however, they showed an increase ( P ? 0.05) in creatine kinase after exercise. For the remaining five participants, there was an increase in T2 signal intensity of the loaded vastus intermedius and vastus lateralis. These changes in MRI were accompanied by an increase in MHC plasma concentration ( P ? 0.01) as well as an increase in creatine kinase ( P ? 0.01). We suggest that changes in MRI T2 signal intensity after muscle damage induced by eccentric exercise are closely related to damage to structurally bound contractile filaments of some muscle fibres. Additionally, MHC plasma release indicates that this damage affects not only fast-twitch fibres but also some slow-twitch fibres. 相似文献
27.
The concept “Psychosocial Resources in Sport” (Sygusch, Ein sportartenorientiertes Förderkonzept für Schule und Verein. Schorndorf: Hofmann, 2007) substantiates methodical measures to systematically promote resources such as self-concept, self-efficacy, group cohesion, and social competence. In the PRimus-study this concept was implemented in handball and apparatus gymnastics over 7 months in 29 training groups (age: 12–16 years). The aim, amongst others, was to evaluate whether the concept is effective in child and youth sport. For this purpose a mixed-method design was chosen. The development of resources were measured through qualitative trainer interviews (n?=?39) as well as quantitative surveys of athletes (IG: n?=?374; KG: n?=?270) over three measurement times. The trainer statements show that the intervention initiated resource strengthening processes which indicate a promotion of resources. The quantitative measurements, however, do not reveal substantial changes throughout the intervention period. The change in behavior of coaches and athletes – regardless of the intervention measures – influences the development of resources. Overall, it must be noted that broad-based intervention concepts, which are also feasible, had difficulty proving the effects and the effectiveness. 相似文献
28.
Academic Functioning and Peer Influences: A Short‐Term Longitudinal Study of Network–Behavior Dynamics in Middle Adolescence 下载免费PDF全文
J. Ashwin Rambaran Andrea Hopmeyer David Schwartz Christian Steglich Daryaneh Badaly René Veenstra 《Child development》2017,88(2):523-543
In this study, the associations between peer effects and academic functioning in middle adolescence (N = 342; 14–15 years old; 48% male) were investigated longitudinally. Similarity in achievement (grade point averages) and unexplained absences (truancy) was explained by both peer selection and peer influence, net of acceptance, and connectedness. Friendships were formed and maintained when adolescents had low levels of achievement or high levels of truancy. Friends influenced one another to increase rather than decrease in achievement and truancy. Moreover, friends’ popularity moderated peer influences in truancy in reciprocal friendships but not in unilateral friendships, whereas friends’ acceptance moderated peer influences in achievement in both unilateral and reciprocal friendships. The findings illustrate the dynamic interplay between peer effects and academic functioning. 相似文献
29.
Wolfgang Wahlster J?rg Baus Christian Kray und Antonio Krüger 《Informatik - Forschung und Entwicklung》2001,16(4):233-241
Zusammenfassung. Die intelligente Ressourcenadaption ist eine der gro?en Herausforderungen für die n?chste Generation mobiler Navigationssysteme.
Da man typischerweise mehrere Fortbewegungsarten oder Verkehrsmittel kombinieren muss, um an einen Zielort zu gelangen, muss
sichergestellt werden, dass mobile, allgegenw?rtige Navigationshilfen dies über eine jeweils situationsangepasste Benutzerschnittstelle
unterstützen. Der notwendige Wechsel zwischen verschiedenen Positionierungstechnologien soll für den Endbenutzer m?glichst
unbemerkt bleiben. Im folgenden wird ein hybrides Personennavigationssystem vorgestellt, das die in bestimmten Fortbewegungssituationen
verfügbaren Positionierungstechnologien und deren Genauigkeit optimal nutzt, um die Pr?sentation der Wegbeschreibung auf verschiedene
Endger?te und Ausgabemodalit?ten sowie die kognitive Ressourcenlage des Benutzers zu adaptieren.
Eingegangen am 28. Februar 2001 / Angenommen am 8. August 2001 相似文献
30.
Christian Walsh 《Decision Sciences Journal of Innovative Education》2023,21(1):37-46
Failure has an important role to play in learning how to navigate highly uncertain organizational environments. But “failing fast” just for its own sake may in fact undermine learning if not set up or handled correctly. Using failure-based pedagogy, including generative failure, whole-person learning, and entrepreneurial thinking, an MBA course was designed and experienced by 48 students in three instances. Structured around a novel guiding framework of “brains, bravery, and belief,” the course has resulted in highly impactful learning for students. Student experiments are typically based around either exploring an entrepreneurial idea, developing or enhancing a particular skill, or applying skills and knowledge to help improve a societal problem. In each case, students are supported but also challenged to go beyond their comfort zones and encounter some intelligent failure in the journey. Regular reflection on their experiences, both from a cognitive and an affective perspective, is an essential element built into the course experience. The course, which itself was an experiment and not without its own instructive failures, is now an essential part of the MBA experience. 相似文献