Medien in pädagogischen Kontexten     

Friederike von Gross  Anna-Maria Kamin  Prof. Dr. Uwe Sander  Dr. Thomas Walden 《Zeitschrift für Erziehungswissenschaft》2013,16(4):777-782

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辅助变元之于命题与量化布尔公式的作用     

乌维·布贝克  汉斯·克莱那·布吕宁 《中山大学学报论丛》2010,3(3)

使用辅助变元来引入定义,在知识表达中是一个流行和有力的技巧,能够得到更短、更自然的编码而无需冗长的重复.这篇论文中,我们形式地定义了辅助变元的概念,检验了其表达力并讨论了有趣的相关应用.我们把以下两者联系起来:一是,反复使用中间结果而不通过定义重复;二是,布尔函数其他表达中的相似概念.特别的,我们表明带定义的命题逻辑与具有任意输出端的布尔线路以及约束变元满足Horn性质的存在量化布尔公式(记作(E)HORNb)具有相同的表达力.本文还考虑了定义结构的限制,以及命题定义的扩充.特别的,我们检验了正命题定义与带存在量化的正定义之间的关系(或等价地,检验了(E)HORNb公式和约束变元未被Horn限定的存在量化的CNF公式(记作(E)CNF*)之间的关系).对命题定义的进一步扩充,是允许在定义中使用任意的量词,或等价地,允许布尔公式的嵌入.我们还证明了,量化CNF公式中的约束变元的表达力,是由子句中被约束部分的极小不可满足子公式或极小假子公式的结构所决定的.  相似文献   

4. Finkbeiner, Claudia; Schnaitmann, Gerhard W.: Lehren und Lernen im Kontext empirischer Forschung und Fachdidaktik     

Uwe Hericks  Ingrid Kunze 《Zeitschrift für Erziehungswissenschaft》2001,4(3):478-480

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Predictor variables of performance in recreational male long-distance inline skaters     

Knechtle B  Knechtle P  Rüst CA  Senn O  Rosemann T  Lepers R 《Journal of sports sciences》2011,29(9):959-966

We investigated the associations between selected anthropometric and training characteristics with race time in 84 recreational male long-distance inline skaters at the longest inline marathon in Europe, the 'Inline One-eleven' over 111 km in Switzerland, using bi- and multivariate analysis. The mean (s) race time was 264 (41) min. The bivariate analysis showed that age (r = 0.30), body mass (r = 0.42), body mass index (r = 0.35), circumference of upper arm (r = 0.32), circumference of thigh (r = 0.29), circumference of calf (r = 0.38), skin-fold of thigh (r = 0.22), skin-fold of calf (r = 0.27), the sum of skin-folds (r = 0.43), percent body fat (r = 0.45), duration per training unit in inline skating (r = 0.33), and speed during training (r = -0.46) were significantly and positively correlated to race time. Stepwise multiple regression showed that duration per training unit (P = 0.003), age (P = 0.029) and percent body fat (P = 0.016) were the best correlated with race time. Race time in a long-distance inline race such as the 'Inline One-eleven' over 111 km with a mean race time of ～260 min might be predicted by the following equation (r(2) = 0.41): Race time (min) = 114.91 + 0:51* (duration per training unit, min) + 0:85* (age, years) +3:78* (body fat, %) for recreational long-distance inline skaters.  相似文献   

Ein Hoarding-Verfahren für ortsbezogene Informationen     

Uwe Kubach und Kurt Rothermel 《Informatik - Forschung und Entwicklung》2001,16(4):189-199

Zusammenfassung.   Mit der zunehmenden Verbreitung mobiler Endger?te w?chst auch der Bedarf in mobilen Umgebungen auf entfernt gespeicherte Informationen zuzugreifen. Da dieser Informationszugriff meist über drahtlose Netzwerke erfolgt, treten in mobilen Informationssystemen h?ufig Probleme wie geringe Bandbreite, gro?e Verz?gerungen oder Verbindungsausf?lle auf. Hoarding-Verfahren versuchen diese Probleme zu l?sen, indem sie Informationen, auf die der Benutzer voraussichtlich zugreifen wird, im voraus übertragen. Dazu müssen sie jedoch vorhersagen, welche Informationen der Benutzer ben?tigen wird. In diesem Beitrag stellen wir ein Hoarding-Verfahren vor, das für diese Vorhersage die Ortsabh?ngigkeit von Informationszugriffen ausnutzt. Wie wir durch Simulationen zeigen, wird der Speicherplatz auf dem Endger?t dadurch sehr effizient genutzt. (Die hier vorgestellte Arbeit ist mit Unterstützung der DFG im Rahmen der Forschergruppe Nexus sowie des Graduiertenkollegs Parallele und Verteilte Systeme entstanden. Eingegangen am 2. Februar 2001 / Angenommen am 1. Juni 2001  相似文献   

Using accelerometry to quantify deceleration during a high-intensity soccer turning manoeuvre     

Niels Jensby Nedergaard  Uwe Kersting 《Journal of sports sciences》2014,32(20):1897-1905

Abstract

The mechanics of cutting movements have been investigated extensively, but few studies have considered the rapid deceleration phase prior to turning which has been linked to muscle damage. This study used accelerometry to examine the influence of turning intensity on the last three steps of a severe turn.

Ten soccer players performed 135° “V” cuts at five different intensities. Resultant decelerations were recorded from a trunk-mounted tri-axial accelerometer. Lower limb kinematics and ground reaction forces (GRF) from the pivot foot-ground contact (FGC) were also monitored.

Average peak trunk decelerations were larger at the two preceding steps (4.37 ± 0.12 g and 4.58 ± 0.11 g) compared to the PIVOT step (4.10 ± 0.09 g). Larger peak joint flexion angular velocities were observed at PRE step (ankle: 367 ± 192 deg.s^?1; knee 493 ± 252 deg.s^?1) compared to PIVOT step (ankle 255 ± 183 deg.s^?1; knee 377 ± 229 deg.s^?1). Turn intensity did not influence peak GRF at PIVOT step.

This study highlights the importance of steps prior to turning and their high-frequency loading characteristics. It is suggested that investigations of lower limb loading during turning should include this deceleration phase and not focus solely on pivot FGC.  相似文献   

Age and gender interactions in short distance triathlon performance     

Franziska Etter  Arkadiusz Bukowski  Christoph Alexander Rüst  Thomas Rosemann  Romuald Lepers 《Journal of sports sciences》2013,31(9):996-1006

Abstract

This study investigated the participation and performance trends as well as the age and gender interaction at the Olympic distance ‘Zürich Triathlon’ (1.5?km swim, 40?km cycle and 10?km run) from 2000 to 2010 in 7,939 total finishers (1,666 females and 6,273 males). Female triathletes aged from 40 to 54 years significantly (P?<?0.05) increased their participation while the participation of younger females and males remained stable. Males of 50–54 years of age and females of 45–49 years of age improved their total race time. For elite top five overall triathletes, mean gender differences in swimming, cycling, running and overall race time were 15.2?±?4.6%, 13.4?±?2.3%, 17.1?±?2.5%, and 14.8?±?1.8%, respectively. For both elite and age group athletes, the gender difference in cycling time was significantly (P?<0.001) lower than for swimming and running. The gender difference in overall Olympic distance triathlon performance increased after the age of 35 years, which appeared earlier compared to long distance triathlon as suggested by previous studies. Future investigations should compare gender difference in performance for different endurance events across age to confirm a possible effect of exercise duration on gender difference with advancing age.  相似文献   

The Role of Motor Competences in Predicting Working Memory Maintenance and Preparatory Processing     

Sebastian Ludyga  Manuel Mücke  Keita Kamijo  Christian Andrä  Uwe Pühse  Markus Gerber  Christian Herrmann 《Child development》2020,91(3):799-813

The purpose of the study was the examination of the longitudinal association between motor competences and changes in preparatory processing during a task requiring working memory maintenance. At baseline, 52 Caucasian children aged 10–12 years completed the MOBAK-5 test battery and a Sternberg task, whereas the cue-P300 and the initial contingent negative variation (iCNV) were recorded via electroencephalography. After 9 months, the Sternberg task was administered again to assess changes in these neurophysiological indices and behavioral performance. Path analyses revealed that motor competences predicted the change in cue-P300 and iCNV from baseline to follow-up. The present findings indicate that the cognitive control strategy during a task demanding working memory maintenance changes as a function of children's baseline motor competences.  相似文献   

Moderate-to-vigorous physical activity,executive functions and prefrontal brain oxygenation in children: A functional near-infrared spectroscopy study     

Manuel Mücke  Christian Andrä  Markus Gerber  Uwe Pühse 《Journal of sports sciences》2018,36(6):630-636

Despite accumulating evidence that regular exercise improves executive functioning, the underlying neurophysiological mechanisms have rarely been investigated. The present study aimed to compare cognitive performance as well as task-specific concentration changes in oxygenated haemoglobin in the prefrontal cortex between children with higher and lower moderate-to-vigorous physical activity (MVPA). Physical activity was measured over 7 consecutive days using actigraphy. Afterwards, participants (N = 50) completed verbal fluency tests (VFTs) and mental arithmetic (MA) for the assessment of cognitive flexibility and working memory capacity. During the tasks, changes of oxygenated haemoglobin were measured with functional near-infrared spectroscopy. Using average MVPA of 11-year-old children as cut-point, the sample was divided into children with lower and higher MVPA. Analyses of variance revealed no significant differences in correct and false responses on the cognitive tests between groups. With regard to oxygenated haemoglobin, no group differences were found for concentration changes in response to the cognitive tasks. In conclusion, VFTs and MA increased children’s activation in prefrontal regions associated with cognitive flexibility and working memory, respectively. However, these executive functions and cortical activation were not different between children with lower and higher MVPA.  相似文献   

Science in the Third Reich: Margit Szöllösi-Janze (ed.), <Emphasis Type="Italic">Science in the Third Reich (German Historical Perspectives,XII</Emphasis>) (Oxford/New York: Berg, 2001), 289 pp., ISBN: 1-85973-421-9     

Wolfgang?Uwe?EckartEmail author 《Minerva》2004,42(4):451-454

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