Search results for "TASK"

Genetic Algorithms Applied to the Design of 3D Photonic Crystals

2011

We aim at determining the optimal configuration of photonic crystal structures capable of carrying out a certain optical task. An exhaustive search would require a high computational cost, in this work we show how genetic algorithms can be applied to reliably find an optimal topology of threedimensional photonic crystals. The fitness, representing the performance of each potential configuration, is calculated by means of finite element analysis. Different experiments are presented in order to illustrate the potential of this 3D design approach.

Understanding Action and Adventure Sports Participation—An Ecological Dynamics Perspective

2017

© 2017, The Author(s). Previous research has considered action and adventure sports using a variety of associated terms and definitions which has led to confusing discourse and contradictory research findings. Traditional narratives have typically considered participation exclusively as the pastime of young people with abnormal characteristics or personalities having unhealthy and pathological tendencies to take risks because of the need for thrill, excitement or an adrenaline ‘rush’. Conversely, recent research has linked even the most extreme forms of action and adventure sports to positive physical and psychological health and well-being outcomes. Here, we argue that traditional framewor…

A dosimetric study on the Ir-192 high dose rate Flexisource

2006

In this work, the dose rate distribution of a new Ir-192 high dose rate source (Flexisource used in the afterloading Flexitron system, Isodose Control, Veenendaal, The Netherlands) is studied by means of Monte Carlo techniques using the GEANT4 code. The dosimetric parameters of the Task Group No. 43 Report (TG43) formalism and two-dimensional rectangular look-up tables have been obtained.

Monte Carlo calculation of the TG-43 dosimetric parameters of a new BEBIG Ir-192 HDR source

2005

Background and purpose: High dose rate (HDR) brachytherapy is a highly extended practice in clinical brachytherapy today. Quality dose rate distribution datasets of the HDR sources used in a clinical treatment are required. Because of the different source designs, a specific dosimetry dataset is required for each source model. In the recently published BRAPHYQS-ESTRO Report, an overview of available dosimetric data for all HDR Ir-192 sources is given, pointing out the lack of data for one of the sources that is used by the BEBIG MultiSource afterloading system (BEBIG GmbH, Germany). The purpose of this study is to obtain detailed dose rate distributions in liquid water media around this sou…

Understanding the limits of self-control: Positive affect moderates the impact of task switching on consecutive self-control performance

2013

Performing consecutive self-control tasks typically leads to deterioration in self-control performance. This effect can be explained within the strength model of self-control or within a cognitive control perspective. Both theoretical frameworks differ in their predictions with regard to the impact of affect and task characteristics on self-control deterioration within a two-task paradigm. Whereas the strength model predicts decrements in self-control performance whenever both tasks require a limited resource, under a cognitive control perspective, decrements should only occur when people switch to a different response conflict in the second task. Moreover, only the cognitive control model …

2017

Moving and acting underwater within recreational or occupational activities requires intact executive functions, since they subserve higher cognitive functions such as successful self-regulation, coping with novel situations, and decision making; all of which could be influenced by nitrogen narcosis due to elevated partial pressure under water. However, specific executive functions that could provide a differentiated view on humans’ cognitive performance ability have not yet been systematically analyzed in full-water immersion, which is a research gap addressed within this approach to contribute to a better understanding of nitrogen narcosis. In this study, 20 young, healthy, and certified …

Dynamics between student vs. teacher perceptions of mathematics task-orientation and mathematics performance among adolescents

2017

This study examined the dynamics between perceptions of mathematics task-orientation and mathematics performance among Finnish adolescents over a period of two last years of secondary school. Task-orientation in math was assessed at the beginning of grade 8 and again at the end of grade 9 using both student and teacher-reports. At the same time points, students' mathematics performance was evaluated via standardized test. The cross-lagged associations of task-orientation and mathematics performance were examined taking account the possible impacts of general cognitive ability, technical reading skills, reading comprehension and gender. The results showed that a high level of mathematics per…

Tasks for enriching the understanding of the concept of linear span

2018

International audience; The concept of linear span is one of the first abstract notions that students encounter in a course on Linear Algebra. Using the theoretical construct of concept image and concept definition (Tall & Vinner, 1981) along with observations about teaching and learning Linear Algebra, we present two tasks designed to enrich students' concept image regarding linear span. These tasks could be included in a problem workshop of an introductory university course on Linear Algebra. Each task is carefully created and/or selected so as to foster the ground for potential conflict factors to arise and be confronted. A preliminary evaluation shows that the tasks are well received by…

Mediating Mathematics Teaching Development and Pupils’ Mathematics Learning: The Life Cycle of a Task

2011

A developmental research project in Norway, Learning Communities in Mathematics (LCM), a collaboration between university and schools, uses mathematical tasks as a basis for developing community in project workshops and for teachers’ design of tasks for classrooms. An aim in the project is that teachers and didacticians, through inquiry into design and use of tasks and reflection on and analysis of their use, will learn more about creating effective learning situations for pupils in mathematics. The processes involved are exemplified through an account of the design and use of the Mirror Task. An activity theory analysis traces the elements of learning of participants, teachers and didactic…

The influence of intra-team conflict on work teams' affective climate: A longitudinal study

2008

We analysed whether relationship conflict mediates the link between task conflict and shared affect at the team level of analysis. Moreover, we tested the hypothesis that the relationship between these two types of intra-team conflict would be moderated by team members' interaction. The sample was composed of 156 bank branches. Data were gathered at two points in time. Two affect dimensions (tension and enthusiasm) were measured. The results obtained supported our hypotheses. Relationship conflict fully mediated the relationship between task conflict and team affect. Team members' interaction about team issues moderated the relationship between task conflict and relationship conflict, so th…