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   

Editorial     

Prof. Dr. W. Dörfler 《Educational Studies in Mathematics》1993,24(1):v-v

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Qualitative research methods in education     

Jan-Ingvar Löfstedt 《Interchange》1990,21(4):73-80

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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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Elite football on artificial turf versus natural grass: movement patterns, technical standards, and player impressions     

Andersson H  Ekblom B  Krustrup P 《Journal of sports sciences》2008,26(2):113-122

The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.  相似文献   

Controlling the field of academic economics in Hungary, 1953–1976     

György Péteri 《Minerva》1996,34(4):367-380

Conclusions On the basis of these findings, I suggest that the structure and organisation of the field of Hungarian economics under state socialism should be described as a case of partitioned bureaucracy.⁹ The compromise between research economists and the political elite in the New Course era between 1953 and 1955¹⁰ survived the post-1956 reaction in so far as political economy, with its predominantly legitimatory and ideological functions, remained partitioned from the other sectors in the field through the remainder of the state-socialist period. This secured considerable protection both for Marxist-Leninist political economy—which faced the destabilising effects of exposure to the findings of serious empirical research—and for the other sectors, which were professionally oriented and earnestly interested in the pursuit of unbiased empirical research, free from stifling agitprop interference. Our data concerning the reputational control of the field reflects only one, although very important, aspect of this partitioning. Another and much plainer aspect is that, from the early 1960s, the Agitation and Propaganda Department of the Central Committee no longer exercised control over the field, except in the political economy sector.The proposition about the mechanism paradigm should not be taken seriously as a statement of a Kuhnian type of intellectual organisation of Hungarian economics, with reform economics at its hard theoretical core. But it should certainly be taken seriously as a reflection of the sociopolitical structure which emerged and developed from the mid-1950s onwards. Neither the politicians nor the economists saw as necessary or even contemplated the integration of Hungarian economic research with Western mainstream economic thought. In exchange for the professional expertise and socio-economic intelligence necessary for the exercise of power, Hungary's state-socialist political class offered their economists relative autonomy and freedom from interference. The price the economists had to pay was partly to refrain from openly and systematically challenging the beliefs perpetuated by the political economy of socialism, and partly to accept in their research the paramountcy of policy orientation. But this burden they assumed willingly since it made them the only group within Hungary's academic intelligentsia—indeed, the only group in Hungarian society outside the political class—with the privilege of being coopted to the institutions with power over some restricted domains of policymaking. After 1989, especially under the conservative Antall government, this proved less than advantageous.¹¹ Although the benevolence of many critics is open to question, it could greatly benefit the field if the economists' expulsion from contemporary politics went hand in hand with provision of the material, intellectual and institutional conditions for a new approach where a fundamentally scientific orientation is paramount.  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   

Health science libraries in Sweden: new directions,expanding roles          下载免费PDF全文

Lotta Haglund  Annikki Roos  Petra Wallgren‐Björk 《Health information and libraries journal》2018,35(3):251-255

Librarians in Sweden are facing huge challenges in meeting the demands of their organisations and users. This article looks at four key areas: coping with open science/open access initiatives; increasing demands from researchers for support doing systematic reviews; understanding user experiences in Swedish health science libraries; and the consequences of expanding roles for recruitment and continuing professional development. With regard to changing roles, there is an increasing shift from the generalist towards the expert role. The authors raise the issue as to how to prepare those new to the profession to the changing environment of health science libraries.  相似文献   

The Formation of Swedish Media Studies, 1960–1980     

Mats Hyvönen  Pelle Snickars  Per Vesterlund 《Media History》2018,24(1):86-98

Around 1960, the politics of the emerging media society in Sweden tended to fixate the formative functions of mass communication. The monopoly of public service broadcast media, press subsidies and new tendencies in film policy were some of the issues around which uncertainty prevailed. New methods to provide reliable data were sought by politicians, since empirical facts were required as arguments for an updated media policy. This article examines the different ways that the field of media studies was introduced in Sweden between 1960 and 1980. We argue that Swedish academic media studies departed from, and emerged within, a rather diffuse borderland between industry, politics and academia. The formation of national media research in Sweden can partly be seen as an effect of politicians and the media industry wanting to be better informed on issues such as media influence, media ownership and the habits and composition of the media audience.  相似文献