Developing and evaluating a strategy for learning from animations

Based on current theories of multimedia learning, we propose a strategy for learning from animations. Two different experimental studies were conducted in order to evaluate the strategy. In the first study, 22 sixth graders learned from an animation without the strategy while 21 students were encouraged to make use of the proposed strategy during learning; use of the strategy was not monitored. The students who were encouraged to take advantage of the strategy learned significantly more than the students who were not asked to do so. In the second study, three groups of sixth graders were investigated. The first group consisted of 49 students who learned from an animation without the strategy. The second group consisted of 52 students who were encouraged to make use of the strategy during learning; but use of the strategy was not monitored. The third group consisted of 53 students who were also encouraged to make use of the strategy during learning and their use of the strategy was monitored. The results of the second study replicated the findings of the first study. Furthermore, learning was most successful when the students' use of the learning strategy was monitored.     

The impacts of new governance on teaching at German universities. Findings from a national survey

In this article we will present findings from a national survey questioning the actual impact of the new governance structures at German universities on academic teaching. To begin with, we give a theoretical underpinning to the economization of higher education institutions (HEIs) according to Principal-Agent Theory. This allows for the development of hypotheses about the influence of new selective incentives (merit pay, performance-related budgeting, Management by Objectives, teaching awards) on the professors’ academic teaching behavior. Instructed by critical considerations on Principal-Agent Theory we extended the axiomatics of this economic theory by incorporating concepts like work task motivation and academic socialization for a supposedly more comprehensive explanation. Data from a nationwide German survey allows us then to test our theory-driven assumptions. Our target population was the entire collectivity of all professors at German universities from which we could draft a sample 8,000 individuals. An estimation of four different OLS-regression models shows that the hypotheses derived from Principal-Agent Theory must be rejected whereas the hypotheses based on motivational aspects and socialization processes can be confirmed. Based on our analysis we can conclude that for the status quo of implementation there are no direct influences of new selective incentives on the actual teaching performance whereas we have strong indications for altered mechanisms of enculturation in the field of universities. New Public Management (NPM) seems to produce a new breed of professors whose preferences and practice are conditioned by the imperatives evoked by this new managerialism.     

辅助变元之于命题与量化布尔公式的作用

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.     

Ein Hoarding-Verfahren für ortsbezogene Informationen

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     

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

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.     

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

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.     

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

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.