Effect of different loading conditions on running mechanics at different velocities     

Germán Carretero-Navarro  Doménico Cherubini  Wolfgang Taube 《European Journal of Sport Science》2019,19(5):595-602

Weighted vests are widely used to improve running economy and performance. However, it is not well-studied how running mechanics are adapted to counteract the higher peak vertical ground reaction forces (Fpeak) while running with such a device. Therefore, the present study aimed to investigate the effects of different loading conditions on running mechanics at different velocities. Thirteen subjects participated in two separate sessions one week apart. In the first session, maximal aerobic speed (MAS) was determined through a maximal incremental running test while in the second session, they were instructed to run during one minute under different loading (0%, +10% and +20% of body mass [BM]) and velocity (60%, 80% and 100% of MAS) conditions in a random order. Spatiotemporal data were recorded and then running mechanics modelled using the spring-mass model. The main results indicated that vertical and leg stiffness (Kvert and Kleg, respectively) were increased (P?P?>?.05) when load was changed. At the same time, alterations of the running kinematics were observed such as longer contact times, reduced flight times, stride frequencies and step lengths, as well as an increase of the centre of mass dynamics. Based on these results it is assumed that runners maintain a certain stiffness level for each velocity despite different loading conditions. As a consequence, Fpeak increases and this probably causes spatiotemporal adjustments in the movement kinematics.  相似文献   

REAL: Ein ressourcenadaptierendes mobiles Navigationssystem     

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   

Emergent rationality in technological policy: Nuclear energy in the Federal Republic of Germany     

Wolfgang Fach  Edgar Grande 《Minerva》1992,30(1):14-27

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Editorial     

Donsbach  Wolfgang; Noelle-Neumann  Elisabeth; Traugott  Michael W.; Worcester  Robert 《Int. Journal of Public Opinion Research》2006,18(3):273-274

This issue of the Journal contains three interesting articlesabout central aspects of public opinion research, as well asan equal number of research notes that reflect the range oftopics that interest all public opinion researchers. Toshio Takeshita takes a turn at reconceptualizing agenda-settingstudies, using a taxonomy  相似文献   

Channel adaptive rate control for energy optimization     

Blanch Carolina  Pollin Sofie  Lafruit Gauthier  Eberle Wolfgang 《浙江大学学报(A卷英文版)》2006,7(1):82-88

Low energy consumption is one of the main challenges for wireless video transmission on battery limited devices. The energy invested at the lower layers of the protocol stack involved in data communication, such as link and physical layer, represent an important part of the total energy consumption. This communication energy highly depends on the channel conditions and on the transmission data rate. Traditionally, video coding is unaware of varying channel conditions. In this paper, we propose a cross-layer approach in which the rate control mechanism of the video codec becomes channel-aware and steers the instantaneous output rate according to the channel conditions to reduce the communication energy. Our results show that energy savings of up to 30% can be obtained with a reduction of barely 0.1 dB on the average video quality. The impact of feedback delays is shown to be small. In addition, this adaptive mechanism has low complexity, which makes it suitable for real-time applications.  相似文献   

Zivilgesellschaftliche Beteiligung in der Altersspanne von 13 und 32?Jahren �C Entwicklung, Bedingungsfaktoren, Kontexte     

Martina Gille  Johann de Rijke  Dr. Wolfgang Gaiser 《Zeitschrift für Erziehungswissenschaft》2011,14(4):551-579

Being active in civic organizations can be expressed in multifarious forms of participation and commitment. With regard to individuals, the learning context it provides fosters personal development, sympathy for other perspectives, and social competencies in general and is, thus, particularly meaningful for young people in their second and third decades. With regard to organizations, civic participation strengthens the integration and dynamic adaptation of institutions to changing environments and, on a macro-level, raises social cohesion. The contexts of participation are various: not only in educational institutions and the world of work, but also in clubs, organizations and less formal groups, which are involved in social and political issues. Socio-structural and motivational factors, but also belonging to social networks determine the involvement in such forms of civic participation. Additionally, there is evidence of a mutual reinforcement of participation in different contexts. This is shown by the results of the DJI-Survey AID:A 2009.  相似文献   

Current Trends in Educational Research in Europe     

Wolfgang Mitter 《欧洲师范教育杂志》1992,15(1-2):53-64

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Children''s Understanding of Cognitive Cuing: How to Manipulate Cues to Fool a Competitor     

Beate Sodian  Wolfgang Schneider 《Child development》1990,61(3):697-704

4-6-year-old children's understanding of cognitive cuing was studied in 2 experiments using a strategic interaction paradigm. Children could fool a competitor by hiding targets in locations that were labeled with semantically weakly associated cues and help a cooperative partner by hiding them in semantically highly associated locations. Very few 4-year-olds, half the 5-year-olds, and almost all 6-years-olds appropriately chose semantically highly vs. weakly associated hiding places to make the targets easy vs. difficult to find. The second experiment showed that 4-year-olds did not strategically manipulate cues as sources of information, although they themselves proficiently used them as such in a search task. These findings are discussed with regard to research on children's developing understanding of origins of knowledge and belief and with regard to recent claims that young preschoolers possess a metacognitive understanding of cognitive cuing.  相似文献   

Factors influencing the incidence of utilization deficiencies and other patterns of recall/strategy-use relations in a strategic memory task     

Schwenck C  Bjorklund DF  Schneider W 《Child development》2007,78(6):1771-1787

Factors that influence the incidence of utilization deficiencies and other recall/strategy-use patterns on a strategic memory task were evaluated in two hundred and fourteen 7- and 9-year-old children. Both utilization deficiencies and the incidence of children showing increases in both recall and strategy use over phases were more likely to be observed on phase transitions involving prompting or when different lists of items were included on consecutive trials; in contrast, increases in recall in the absence of increases in strategy use were more likely to be found between trials consisting of the same stimulus items. This research clearly indicates that patterns of recall/strategy-use relations, including utilization deficiencies, vary meaningfully with the age of the child and a variety of contextual factors.  相似文献   

Editorial     

Donsbach  Wolfgang; Traugott  Michael W. 《Int. Journal of Public Opinion Research》2007,19(3):285-286

This issue of the International Journal of Public Opinion Researchassembles six contributions—three articles and three researchnotes—that represent the diversity of subjects, methods,and research sites that we aim at. The first article is by agroup of (mostly) Ohio State University scholars (Lindsay H.Hoffman, Carroll J. Glynn, Michael E. Huge, Rebecca Border Sietman,and Tiffany Thomson) who used two surveys about a school districtballot issue to study the process of opinion formation. Drawingon  相似文献