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Search Results: 1 - 4 of 4 matches for " EJM Veling "
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An efficient optimisation method in groundwater resource management
JM Ndambuki, FAO Otieno, CBM Stroet, T Terlaky, EJM Veling
Water SA , 2003,
Abstract: Uncertainty in input parameters to groundwater flow problems has been recognised as an impediment to designing efficient groundwater management strategies. The most popular approach to tackling this problem has been through the Monte Carlo approach. However, this approach is generally too expensive in terms of computer time because of the number of scenarios required to ensure reliable statistics. Furthermore, solutions obtained through this approach are not necessarily robust. In this paper, it is shown how groundwater management problems, where input parameters are uncertain can be reformulated as second-order cone optimisation (SOCO) problems, which are efficiently solved by recently developed interior-point methods. Results for a real-world case application of a groundwater aquifer found in Kenya are presented. Water SA Vol.29(4): 359-363
When unconscious rewards boost cognitive task performance inefficiently: the role of consciousness in integrating value and attainability information
Claire M. Zedelius,Harm Veling,Henk Aarts
Frontiers in Human Neuroscience , 2012, DOI: 10.3389/fnhum.2012.00219
Abstract: Research has shown that high vs. low value rewards improve cognitive task performance independent of whether they are perceived consciously or unconsciously. However, efficient performance in response to high value rewards also depends on whether or not rewards are attainable. This raises the question of whether unconscious reward processing enables people to take into account such attainability information. Building on a theoretical framework according to which conscious reward processing is required to enable higher level cognitive processing, the present research tested the hypothesis that conscious but not unconscious reward processing enables integration of reward value with attainability information. In two behavioral experiments, participants were exposed to mask high and low value coins serving as rewards on a working memory (WM) task. The likelihood for conscious processing was manipulated by presenting the coins relatively briefly (17 ms) or long and clearly visible (300 ms). Crucially, rewards were expected to be attainable or unattainable. Requirements to integrate reward value with attainability information varied across experiments. Results showed that when integration of value and attainability was required (Experiment 1), long reward presentation led to efficient performance, i.e., selectively improved performance for high value attainable rewards. In contrast, in the short presentation condition, performance was increased for high value rewards even when these were unattainable. This difference between the effects of long and short presentation time disappeared when integration of value and attainability information was not required (Experiment 2). Together these findings suggest that unconsciously processed reward information is not integrated with attainability expectancies, causing inefficient effort investment. These findings are discussed in terms of a unique role of consciousness in efficient allocation of effort to cognitive control processes.
Promising High Monetary Rewards for Future Task Performance Increases Intermediate Task Performance
Claire M. Zedelius, Harm Veling, Erik Bijleveld, Henk Aarts
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042547
Abstract: In everyday life contexts and work settings, monetary rewards are often contingent on future performance. Based on research showing that the anticipation of rewards causes improved task performance through enhanced task preparation, the present study tested the hypothesis that the promise of monetary rewards for future performance would not only increase future performance, but also performance on an unrewarded intermediate task. Participants performed an auditory Simon task in which they responded to two consecutive tones. While participants could earn high vs. low monetary rewards for fast responses to every second tone, their responses to the first tone were not rewarded. Moreover, we compared performance under conditions in which reward information could prompt strategic performance adjustments (i.e., when reward information was presented for a relatively long duration) to conditions preventing strategic performance adjustments (i.e., when reward information was presented very briefly). Results showed that high (vs. low) rewards sped up both rewarded and intermediate, unrewarded responses, and the effect was independent of the duration of reward presentation. Moreover, long presentation led to a speed-accuracy trade-off for both rewarded and unrewarded tones, whereas short presentation sped up responses to rewarded and unrewarded tones without this trade-off. These results suggest that high rewards for future performance boost intermediate performance due to enhanced task preparation, and they do so regardless whether people respond to rewards in a strategic or non-strategic manner.
Le Syndrome de Denys-Drash, une Cause Rare de Syndrome Néphrotique : à Propos d’un Cas en Milieu Pédiatrique Tropical
LY Adonis-Koffy, KV Assê, F Kouassi, G Diarrassouba, EJM Koutou, E Niamien, P Coulibaly, G Desch enes
Clinics in Mother and Child Health , 2011,
Abstract: Le syndrome de Denys-Drash (DD) est une affection génétique rare due à la mutation du gène WT1, impliqué dans la morphogenèse des organes génitaux externes et du rein. Il associe un syndrome néphrotique congénital et une ambigu té sexuelle. Les premiers signes surviennent dès les 3 premiers mois de vie sous forme d’une sclérose mésangiale diffuse posant un véritable problème thérapeutique. L’évolution spontanée se fait vers une insuffisance rénale terminale et vers une tumeur de Wilms et/ou un gonadoblastome. Dans cet article, nous rapportons le cas d’un syndrome de DD chez un nourrisson de race noire agé de 6 mois dans l’unité de néphrologie pédiatrique du CHU de Yopougon. Nous discutons `a partir d’une revue de la littérature les principaux aspects diagnostics, thérapeutiques et évolutifs de ce syndrome. Nous insistons sur la nécessité d’une collaboration multidisciplinaire incluant les obstétriciens, néonatalogistes, chirurgien pédiatres et néphropédiatres pour un diagnostic précoce et une prise en charge adaptée. Mots Clés syndrome néphrotique congénital ; syndrome de Denys-Drash ; C te d’Ivoire
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