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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East Meets West in Assessment Development: Western Technical Assistance to Eastern Needs. Part III. Reform of an Examination System: Shoulder to Shoulder in the Polish SMART Project     

Annemarie de Knecht-van Eekelen  Steven Bakker  Gerben van  Lent 《Educational Measurement》2001,20(3):33-35

This is Part III of a three part series describing the consultancy and training demands that are encountered in technical assistance projects in Central and Eastern Europe. Part I dealt with strategic issues for a successful delivery of "Western Technical Assistance to Eastern Needs." Part II highlighted project management and co-operation aspects in delivering support to the Romanian Assessment and Examination Service. In this part, we address training of Polish subject experts who were preparing to take on responsibility for a decentralized and strongly innovative final exam, the Matura.  相似文献   

Coordination variability and skill development in expert triple jumpers   总被引：1，自引：0，他引：1  

Wilson C  Simpson SE  van Emmerik RE  Hamill J 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(1):2-9

The aim of this study was to examine the influence of skill of expert triple jumpers on the coordination variability of lower extremity intra-limb couplings. In contrast to the traditional motor learning perspective, we hypothesized that as skill and thus performance increases, movement coordination variability will also increase. Three-dimensional kinematic and ground reaction force data were collected during the hop-step transition phase of the triple jump. Relative motion plots and a modified vector coding technique were used to quantify the coordination variability across the trials. The results were consistent with a U-shaped curve, representing coordination variability, as skill increases. The high coordination variability in less skilled athletes is present while the appropriate characteristics defining the movement coordination patterns are acquired. This coordination variability may not be beneficial to performance. As the refinement of these characteristics is achieved, coordination variability decreases, resulting in a more consistent or regulated performance. In the final stages of developing a skilled performance, a functional variability is accessed that brings flexibility to the system allowing it to cope with perturbations. This study highlights the need to address the learning effect when analysing coordination variability from a dynamical systems perspective.  相似文献   

The condition is critical: continuing professional development of library and information services staff     

John van Loo  MARGARET REDFERN 《Health information and libraries journal》1995,12(1):13-21

The Dynamics of Opinion Formation in Local Popular Referendums: Why the Dutch Always Say No   总被引：1，自引：0，他引：1  

Neijens  Peter; van Praag  Philip 《Int. Journal of Public Opinion Research》2006,18(4):445-462

There is growing research on voting behavior in referendums.However, the dynamics of opinion formation in popular referendums,referendums initiated by the electorate to approve or rejectdecisions made by representative bodies, has not yet been studied.This is especially unfortunate as voting decisions in popularreferendums differ from those in other referendums in interestingways. Opinion formation can be a very dynamic process in popularreferendums, making the referendum campaign crucial. This paperstudies the dynamics of opinion formation in popular referendumsand relates them to particular characteristics of the campaignsand the issues at hand. Based on the literature, we consideredthe effects of the intensity of the yes and no campaigns, familiaritywith the issue, and partisan cues. Our study uses content analysisdata and data from public opinion surveys dealing with variouspopular referendums held in the Netherlands. The study revealedseveral factors that contributed to the volatility of opinionsin the referendum campaigns: the issue (new and did not fittraditional political schemes), lack of support from societaland community organizations for the position of the local authorities,and low profile campaigns on the part of local authorities.While some of these factors are general and may play a rolein referendums everywhere, some can be considered ‘typicallyDutch’, related to the characteristics of popular referendumsin the Netherlands and the country’s political system.  相似文献   

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   

Recording and Accounting for Stakeholder Involvement in Systematic Reviews          下载免费PDF全文

Marieke C. Saan  Hennie R. Boeije  Jane N. T. Sattoe  Marjolijn I. Bal  Marjolein Missler  Floryt van Wesel 《Health information and libraries journal》2015,32(2):95-106

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Neuroanatomy Learning: Augmented Reality vs. Cross-Sections     

Dylan J.H.A. Henssen  Loes van den Heuvel  Guido De Jong  Marc A.T.M. Vorstenbosch  Anne-Marie van Cappellen van Walsum  Marianne M. Van den Hurk  Jan G.M. Kooloos  Ronald H.M.A. Bartels 《Anatomical sciences education》2020,13(3):353-365

Neuroanatomy education is a challenging field which could benefit from modern innovations, such as augmented reality (AR) applications. This study investigates the differences on test scores, cognitive load, and motivation after neuroanatomy learning using AR applications or using cross-sections of the brain. Prior to two practical assignments, a pretest (extended matching questions, double-choice questions and a test on cross-sectional anatomy) and a mental rotation test (MRT) were completed. Sex and MRT scores were used to stratify students over the two groups. The two practical assignments were designed to study (1) general brain anatomy and (2) subcortical structures. Subsequently, participants completed a posttest similar to the pretest and a motivational questionnaire. Finally, a focus group interview was conducted to appraise participants’ perceptions. Medical and biomedical students (n = 31); 19 males (61.3%) and 12 females (38.7%), mean age 19.2 ± 1.7 years participated in this experiment. Students who worked with cross-sections (n = 16) showed significantly more improvement on test scores than students who worked with GreyMapp-AR (P = 0.035) (n = 15). Further analysis showed that this difference was primarily caused by significant improvement on the cross-sectional questions. Students in the cross-section group, moreover, experienced a significantly higher germane (P = 0.009) and extraneous cognitive load (P = 0.016) than students in the GreyMapp-AR group. No significant differences were found in motivational scores. To conclude, this study suggests that AR applications can play a role in future anatomy education as an add-on educational tool, especially in learning three-dimensional relations of anatomical structures.  相似文献