The effect of caffeine ingestion on human neutrophil oxidative burst responses following time-trial cycling

Following fixed-duration exercise of submaximal intensity, caffeine ingestion is associated with an attenuation of the exercise-induced decline in N-formyl-methionyl-phenyl-alanine (f-MLP) stimulated neutrophil oxidative burst. However, the response following high-intensity exhaustive exercise is unknown. Nine endurance-trained male cyclists ingested 6 mg caffeine or placebo per kilogram of body mass 60 min before cycling for 90 min at 70% of maximal oxygen consumption (VO2max) and then performing a time-trial requiring an energy expenditure equivalent to 30 min cycling at 70% maximum power output. Time-trial performance was 4% faster in the caffeine than in the placebo trial (P = 0.043). Caffeine was associated with an increased plasma adrenaline concentration after 90 min of exercise (P = 0.046) and immediately after the time-trial (P = 0.02). Caffeine was also associated with an increased serum caffeine concentration (P < 0.01) after 90 min of exercise and immediately after the time-trial, as well as 1 h after the time-trial. However, the f-MLP-stimulated neutrophil oxidative burst response fell after exercise in both trials (P = 0.002). There was no effect of caffeine on circulating leukocyte or neutrophil counts, but the lymphocyte count was significantly lower on caffeine (20%) after the time-trial (P = 0.003). Our results suggest that high-intensity exhaustive exercise negates the attenuation of the exercise-induced decrease in neutrophil oxidative burst responses previously observed when caffeine is ingested before exercise of fixed duration and intensity. This may be associated with the greater increase in adrenaline concentration observed in the present study.     

An activity theoretical perspective towards the design of an ICT‐enhanced after‐school programme for academically at‐risk students

This paper examines how a game‐like 3D Multi‐User Virtual Environment (MUVE), Quest Atlantis (QA), is used in an after‐school programme to engage a group of 14 academically at‐risk primary students in their learning. It adopts an activity theoretical perspective to identify the disturbances and contradictions during the implementation of the after‐school programme. Based on the analysis of these disturbances and contradictions, the main findings highlight: (1) the importance of the less visible social mediators – the rules, community, and division of labour – in the programme; (2) the pivotal role of the teacher; and (3) the role of QA as both a tool and an object to the students. The findings suggest the importance of the social context where information and communication technology (ICT) is used and the possible use of its engaging elements to first extrinsically motivate these students in their learning.

Eine theoretische Perspektive: Aktivität in Richtung des Designs eines ICT verbesserten ausserschulischen Programms für Risikostudenten

Dieses Papier prüft, wie eine spielähnliche 3D‐Multibenutzer Umgebung (MUVE), “Quest Atlantis (QA)” bei einem außerhalb der Schule benutzten Programms verwendet wird, um eine wissenschaftlich gefährdete 14‐er Studentengruppe in ihrem Lernen anzusprechen. Die Analyse auf Basis der Störungen und Widersprüche zeigt die (1) Wichtigkeit von weniger sichtbaren Sozialmediatoren – die Regeln, die Gemeinschaft und Arbeitsteilung – im Programm, (2) die entscheidende Rolle der Lehrer und (3) die Funktion des Spiels QA sowohl als Werkzeug als auch als Gegenstand für die Studenten. Die Ergebnisse zeigen die Wichtigkeit des sozialen Kontexts wo Informations‐ und Kommunikationstechnologie (ICT) benutzt und gebraucht werden und der mögliche Gebrauch seiner verbindenden Elemente erstmals von außen motivieren das Lernen dieser Studenten.

Perspective théorique sur une activité visant à la conception d’un programme extra scolaire renforcé par les TICE et destiné aux élèves en difficulté

Cet article examine comment on utilise un environnement virtuel à utilisateurs multiples (MUVE) Quest Atlantis (QA) en 3D dans un programme extra scolaire pour impliquer dans leur apprentissage un groupe de 14 élèves en difficulté scolaire. On a adopté une perspective théorique de l’activité pour identifier les troubles et les contradictions rencontrés pendant la mise en place de l’activité extra scolaire. En se fondant sur l’analyse de ces troubles et contradictions, les résultats obtenus font principalement ressortir: (1) l’importance des médiateurs sociaux moins visibles comme_les règles, le groupe, et la répartition des tâches_dans le programme; (2) le rôle central de l’enseignant et (3) le rôle de QA à la fois comme outil et comme objet pour les élèves. Ces observations font apparaître l’importance du contexte social là o[ugrave] on utilise les technologies de l’information et de la communication et le recours possible à leurs facteurs d’implication pour commencer de l’extérieur à motiver ces élèves pour leur apprentissage.

Una perspectiva teórica sobre una actividad conduciendo a un programa posescolar apoyado por las TICs dedicado a los alumnos «en peligro»

Este artículo examina como se utiliza un entorno lúdico virtual en 3D, Quest Atlantis (QA) para usuarios multiples (MUVE) dentro de un programa posescolar para incentivar a un grupo de alumnos «en peligro» para que aprenden. Se adoptó una perspectiva teórica activa para identificar los trastornos y contradicciones encontradas durante la implantación del programa posescolar. Basandose en el análisis de esos trastornos y contradicciones, los principales resultados han destacado (1) la importancia de los mediadores sociales menos visibles, las reglas, la comunidad y la división del trabajo_dentro del programa (2) el papel fundamental del profesor y (3) el papel de QA a la vez como herramienta y como objeto para los alumnos. Esas observaciones resaltan la importancia del contexto social cuando se usan las tecnologías de la información y de la comunicación (TIC) y el posible uso de sus elementos cautivadores para dar a esos alumnos el primer incentivo externo de su aprendizaje.     

Direction dependence of displacement time for two-fluid electroosmotic flow

Electroosmotic flow that involves one fluid displacing another fluid is commonly encountered in various microfludic applications and experiments, for example, current monitoring technique to determine zeta potential of microchannel. There is experimentally observed anomaly in such flow, namely, the displacement time is flow direction dependent, i.e., it depends if it is a high concentration fluid displacing a low concentration fluid, or vice versa. Thus, this investigation focuses on the displacement flow of two fluids with various concentration differences. The displacement time was determined experimentally with current monitoring method. It is concluded that the time required for a high concentration solution to displace a low concentration solution is smaller than the time required for a low concentration solution to displace a high concentration solution. The percentage displacement time difference increases with increasing concentration difference and independent of the length or width of the channel and the voltage applied. Hitherto, no theoretical analysis or numerical simulation has been conducted to explain this phenomenon. A numerical model based on finite element method was developed to explain the experimental observations. Simulations showed that the velocity profile and ion distribution deviate significantly from a single fluid electroosmotic flow. The distortion of ion distribution near the electrical double layer is responsible for the displacement time difference for the two different flow directions. The trends obtained from simulations agree with the experimental findings.     

基于大学生成功学习的美国本科新生体验计划

美国新生体验计划不是一个单独的项目、活动或课程,而是新生们在本科第一年中的经验总和。新生这些体验大都来自于大学为他们设计的课程以及课外活动,最终是为了让学生们更好地适应大学学习和生活并获得成功。     

Understanding the relationship between Singapore preservice teachers’ ICT course experiences and technological pedagogical content knowledge (TPACK) through ICT course evaluation

Teacher education institutions conduct information and communications technology (ICT) courses to prepare preservice teachers (or initial teacher education candidates) to support their teaching practice with appropriate ICT tools. ICT course evaluations based on preservice teachers’ perception of course experiences are limited in indicating the kinds of ICT integration knowledge or technological pedagogical content knowledge (TPACK) preservice teachers have gained throughout the course. Preservice teachers’ ICT course experiences was found to influence their intentions to integrate ICT but its influence on their TPACK perceptions, if better understood, can inform teacher education institutions about the design of ICT courses. This study describes the design and validation of an ICT course evaluation instrument that examines preservice teachers’ perceptions of ICT course experiences and TPACK. Hierarchical regression analysis was performed on survey results collected from a graduating cohort of 869 Singapore preservice teachers who had undergone a compulsory ICT course during their teacher training program. These preservice teachers were being prepared to teach the different subject areas at primary, secondary, and junior colleges (or postsecondary institutions for 17–19 year olds) in Singapore. The regression model showed that preservice teachers’ perceived TPACK was first influenced by their perceptions of course experiences that supported the development of intermediary TPACK knowledge components such as technological knowledge and technological pedagogical knowledge. The methodological implications for the design of ICT course evaluation surveys and the practical applications of survey results to the refinement of ICT course curriculum are discussed.