Robuste Indizes für Projection Pursuit

Die moderne und hoch komplexe Fertigung, z.B. in der Halbleiterindustrie, erfordert für die dabei anfallenden Messdaten der Anlagen- bzw. Prozessparameter multivariate Analysemethoden. Eine dieser m?glichen Analysemethoden ist Projection Pursuit (PP). Dieses Verfahren ist durch geschickte Wahl des so genannten Projektionsindex in der Lage, verschiedenste Datencharakteristika zu detektieren und diese auf anschauliche Weise zu visualisieren. Bei den Projektionsindizes handelt es sich um Funktionen, die eine Projektion auf unterschiedliche Merkmale hin bewerten und dabei jeder Projektion einen Funktionswert zuweisen. Dieser Funktionswert spiegelt die Aussagekraft der Projektion (in Abh?ngigkeit vom verwendeten Index) wider. Die Auswahl bzw. der Aufbau dieser Indizes ist hierbei von entscheidender Bedeutung. Alle hier vorgestellten Indizes zeichnen sich vor allem durch ihren robusten Charakter gegenüber durch Ausrei?er kontaminierte Daten, wie sie in realen Datenszenarien vorkommen, aus. Die durch Anwendung dieser Indizes gewonnenen Einblicke in die komplexe Struktur der Daten erm?glichen es, hochdimensionale Parameterabweichungen und komplexe Zusammenh?nge innerhalb der Daten zu finden.     

Teaching groups as midlevel sociocultural contexts for developing teaching and learning: a case study and comparison to microcultures

Using a case-study approach, the structures, interactions and cultures in four teaching groups at a New Zealand university are explored. The aim of the research is to better understand the potential of teaching groups for assisting academic development. To contextualize this work, the case-study outcomes are compared to research on microcultures. Similarities between strong teaching groups and strong microcultures are found, pointing to the potential of drawing on findings from microculture research. In particular, the use of social commons as a theoretical framework seems indicated, presenting teaching quality as a group and not just individual concern. Differences between the contexts stem from the sole focus of teaching groups on teaching compared to the combined research and teaching mandate of microcultures. As research often dominates teaching, the suggestion is made that teaching groups provide more suitable contexts for addressing teaching issues. The research recommends that organizational units in higher education should identify and analyse teaching groups and build on those groups in addressing teaching quality.     

诺贝尔奖得主寄语中国未来的科学发展

5月25—26日,在纪念国家自然科学基金委员会成立20周年的“21世纪科学前沿与中国的机遇”高层论坛上,6位诺贝尔奖得主做了精彩报告。在对中国科学的未来发展寄予殷切期望的同时,他们也对中国的科技政策提出了具有启发性的建议。现摘编如下:诺贝尔化学奖得主、美国耶鲁大学教授S     

Effect of environmental feedbacks on pacing strategy and affective load during a self-paced 30 min cycling time trial

The purpose of this study was to analyze the pacing strategy and its affective consequences during self-paced cycling time trials (TT) performed at different severity of hypoxia. Eight competitive cyclists performed five 30 min self-paced TTs at their best performance in the following conditions: 1) normobaric normoxia (NN_SL); 2) normobaric hypoxia under two simulated altitudes: 2000 m (NH₂₀₀₀) and 3500 m (NH₃₅₀₀) and 3) normobaric hypoxia but the cyclists were deceived and thought to be at sea level for 2000 m (DecNH₂₀₀₀) and 3500 m (DecNH₃₅₀₀). Power Output (PO), oxygen uptake (VO₂), and blood lactate concentration ([La]) were recorded to assess exercise intensity and physiological adaptations. The rate of perceived exertion (RPE) and pleasure were measured with a CR10 Borg scale to evaluate the affective load (AL). PO and VO₂ decreased with the severity of hypoxia but no significantly difference on performance was measured between deceived and real conditions, except for pacing strategy. The started intensity depends on the exercise expectations, but PO was rapidly adjusted with the physiological constraints and the rate of increase of RPE. Finally, AL did not reach maximal values so that the athletes sustained a physiological and emotional reserve to perform a final spurt.     

The effects of an enhanced quality Physical Education programme on the physical activity levels of Grade 7 learners in Potchefstroom,South Africa

Background: The absence of Physical Education (PE) from the South African school curriculum before its reintroduction in recent years contributed to health concerns regarding the low physical activity (PA) levels of children and adolescents in South Africa.

Purpose: This study evaluated the effects of a once-a-week enhanced quality PE programme on the PA levels of South African Grade 7 learners.

Methods: Using a pre-test and post-test control-group design, 110 Grade 7 learners aged 12–13 years (experimental school, n?=?40; control schools, n?=?70) from two primary schools in Potchefstroom, South Africa, were studied. They participated in a 12-week PE intervention programme based on the guidelines of the South African Curriculum and Assessment Policy Statement, which allocates one hour per week to PE teaching. The intervention included five quality-enhancing components, namely well-trained teachers, homework activities, a reward system, hand-made apparatus and the monitoring of activity intensity. In the experimental school, 40 learners were randomly assigned from the total Grade 7 class (n?=?124) to the experimental group, while two control groups (n?=?37 and n?=?33) were used, one from the same school as the experimental school and the other from a different school. Additionally, to control for PE teacher interaction effect, the experimental group was divided into 4 experimental sub-groups of 10 learners each, which were taught by 4 different PE teachers, and the pre-test and post-test data of these experimental sub-groups were also analysed. Children's PA levels were measured before and after the intervention using a validated Children's Leisure Activities Study Survey questionnaire. The Kruskal–Wallis and Wilcoxon signed-rank tests were used to evaluate the effects of the intervention programme.

Results: No significant differences were found within the experimental group between the 4 experimental sub-groups and between the 2 control groups at pre- and post-test measurements (p?>?.05). There was a significant effect for the experimental group as a whole, as results of the total experimental group showed statistically significant increases in moderate PA (ES?=?0.47; p?=?.014), vigorous PA (ES?=?0.48; p?=?.012) and total PA (ES?=?0.51; p?=?.008) as well as decreases in sedentary behaviours (ES?=?0.39; p?=?.041) after the 12-week intervention programme, whereas no significant changes were found in the control group. Statistically significant improvements were also found in all 4 experimental sub-groups between pre- and post-tests for the time spent in moderate PA (p?=?.028–.05; ES?=?0.23–0.64), vigorous PA (p?=?.018–.036; ES?=?0.23–0.63), total PA (p?=?.017–.05; ES?=?0.30–0.68) and sedentary time (p?=?.014–.049; ES?=?0.26–0.66), whereas no marked changes were observed among the two control groups, indicating no PE teacher interaction effect on the results.

Conclusions: The enhanced quality PE programme can be used as a valuable framework for PE implementation targeted at promoting learners’ PA levels, even in the presence of restricted time allocation, and limited teaching and learning resources.     

The Effects of a Stress Management Course on Counselors‐in‐Training

The effects of a stress management course on the stress knowledge and coping techniques of 101 graduate students in counseling were examined. Participants, drawn from various racial groups, were typically female (79%) and 21 to 55 years of age. Seven of the 8 null hypotheses were rejected. There were significant differences on 6 of the 7 dependent variables (overall knowledge of stress, perceived state and trait anxiety, stress response to positive and negative self‐statements, and general and current stress level). The treatment group learned and implemented stress management strategies to better cope with stress. Recommendations and further directions for research are offered.     

The potential of toe flexor muscles to enhance performance

Abstract

The metatarsal phalangeal joint (MPJ) and its crossing toe flexor muscles (TFM) represent the link between the large energy generating leg extensor muscles and the ground. The purpose of this study was to examine the functional adaptability of TFM to increased mechanical stimuli and the effects on walking, running and jumping performance.

Fifteen men performed a heavy resistance TFM strength training with 90% of the maximal voluntary isometric contraction (MVIC) for 7 weeks (560 contractions) for the left and right foot. Maximal MPJ and ankle plantar flexion moments during MVICs were measured in dynamometers before and after the intervention. Motion analyses (inverse dynamics) were performed during barefoot walking, running, and vertical and horizontal jumping. Athletic performance was determined by measuring jump height and distance.

Left (0.21 to 0.38 Nm · kg^?1; P < 0.001) and right (0.24 to 0.40 Nm · kg^?1; P < 0.001) MPJ plantar flexion moments in the dynamometer, external MPJ dorsiflexion moments (0.69 to 0.75 Nm · kg^?1; P = 0.012) and jump distance (2.25 to 2.31 m; P = 0.006) in horizontal jumping increased significantly.

TFM responded highly to increased loading within a few weeks. The increased force potential made a contribution to an athlete's performance enhancement.     

Three dimensional musculoskeletal modelling of the abdominal crunch resistance training exercise

Abstract

The aim of this study was to evaluate the benefits and limitations of using three dimensional (3D) musculoskeletal modelling (LifeModeler^TM) in assessing the safety and efficacy of exercising on an abdominal crunch resistance training machine. Three anthropometric cases were studied, representing a 5^th percentile female, and 50^th percentile and 95^th percentile male. Results indicated that the LifeModeler^TM default model was capable of solving the forward dynamics simulations without adjustments. The modelling was able to indicate high risk for back injury when performing the abdominal crunch exercise as a result of the unacceptable intervertebral joint loading that occurs during the exercise. Individuals with small anthropometric dimensions such as some females and children cannot be accommodated suitably on the abdominal crunch machine which negatively impacts exercise posture and technique. Hip flexor muscle contribution in the execution of the exercise for the 5^th percentile female was substantial thus reducing the efficacy of the exercise in isolating the abdominal muscles.