Développement et vieillissement des transferts intermodaux d'information

L'intégration de l'information sensorielle est au centre de nombreux travaux en psychologie cognitive. Dans ce travail, nous considérons cette question sous l'angle des interactions intermodales entre vision (V) et toucher (T). Deux types d'appariements sont étudiés : les transferts intramodaux, qui correspondent aux situations de reconnaissance classique au cours desquelles le sujet explore des cibles dans une modalité sensorielle puis doit les reconnaître dans une modalité différente. Ce dernier type d'épreuve nécessite soit une traduction des informations d'un code sensoriel vers un autre (traitement modal), soit la mobilisation d'un code unique commun aux différents sens (traitement amodal). Les études que nous avons menées portent plus précisément sur les effets de l'âge et de la condition de transfert sur les performances, intervenant au cours du développement et du vieillissement. Trois expériences ont été réalisées. La première étude, à laquelle ont participé quatre vingt quinze sujets (enfants, adultes, jeunes et âgés), contraste deux situations de transferts à entrée visuelle, la première correspond à un transfert intramodal (V-V) et la seconde à un transfert intermodal entre vision et touché (V-T). Cent treize personnes (enfants, adultes jeunes et âgés) ont participé à la deuxième expérience qui porte sur les transferts à entrée tactile et contraste deux conditions, l'une de transfert intramodal (T-T) et l'autre de transfert intermodal (T-V). Les résultats de ces deux premières études indiquent un effet significatif du facteur âge sur les performances des sujets, les jeunes adultes obtenant des scores supérieurs aux autres groupes de sujets. De plus, les résultats indiquent un effet significatif de la condition de transfert sur les performances des sujets, allant dans le sens d'une supériorité des performances à entrée visuelle. La troisième expérience porte sur les processus cognitifs susceptibles de médiatiser l'effet de l'âge sur les performances de transfert dans les conditions T-T et T-V. Quarante sujets adultes, jeunes et âgés ont participé à cette étude. Les résultats de cette dernière montrent que des processus différents interviennent dans chaque condition. D'une part, la vitesse de traitement médiatise les effets de l'âge dans la situation intramodale T-T. D'autre part, les facteurs "mémoire de travail verbale" et "imagerie mentale" médiatisent les effets de l'âge sur le transfert intermodal T-V. Ce travail montre que les processus impliqués dans le transfert d'information sensoriel se modifie au cours de la vie. Il indique également que différents facteurs cognitifs sont impliqués selon la nature des transferts réalisés (intramodal ou intermodal) et l'âge des sujets considérés.The sensory information integration concern several studies in cognitive psychology. In this work, we focus on the question of intramodal and cross modal interactions between vision (V) and touch (T). Two types of matching are studied : the first correspond to a classical recognition task in which objects are explored and recognized using the same sensory modality. The second concern cross modal transfer, in which participants explore the target with a modality and recognize it using another modality. This type of task require the information to be translated from a sensory modality to the other (amodal integration), or the use of a single code which is common to different senses (modal integration). Our studies focus on age effect and transfer condition effect on subject's performances, from childhood to elderly. Three experiments were carried out. The first concern 95 subjects (children, young and old adults) took part in the second experiment which concerns two transfers with tactual exploration (T-T and T-V). The results of these two studies indicate a significant age effect on performances, young adults obtain better scores than other groups.Moreover, results indicate a significant transfer condition effect on performances : scores are better when vision is used during the exploration phase. The third esperiment focus on cognitive processes that are plausibly mediate age effect on T-T and T-V conditions. 40 participants (young and old adults) took part in this study. The results show that different processes are involved in each condition. Integration speed mediate age effect in T-T condition, working memory and mental imagery mediate age effect in cross modal transfer T-V condition. This study show that sensory information transfer process changes along life and indicates that different cognitive factors are involved in this process according to transfer condition and people condition and people age-linked experience.TOURS-BU Lettres (372612102) / SudocSudocFranceF

A New Time Delay Model of human granulopoiesis

In this paper the modeling of the human granulopoiesis is carried out. This modeling is an impor tant par t of the fur ther development of a decision support system to assist medical doctor in the treatment of ir2 diation injur es. Refering to an existing model of Fliedner and Steinbach we derive a new nonlinear time delay model of the human granulopoiesis with state dependent delays. Simulations showing the excellent agreement between our new model and the Fliedner-Steinbach model conclude the paper

Development of a Decision Support . . .

In this paper the modeling of the human granulopoiesis is investigated. We present an existing model of Fliedner and Steinbach and show how this biomathematical model is used to predict the sever ness of the injur of an irN diated perN n. In orU r to impr ve the p r diction a new model containing time delays ispr sented. The der ivation of this model is carM ed out using partial differential equations. Fu r herCr e the r al time problems that occur during the prediction will be pointed out

Grosser Systeme Echtzeitoptimierung Schwerpunktprogramm Der Deutschen Forschungsgemeinschaft

In this paper the development of a simulation envir nment for time delay di#er ential equations will bepr sented. After the analysis of the mathematical foundations, the pr ctical implementation using the C++ pr gr amming language will be discussed. Simulations of a biomathematical time delay model of the human gr nulopoiesis ar pr sented and the paper concludes with an er2 r analysis and a discussion of simulation execution times. 1 Introducti6 Delay di#erential equations (DDE) are used to model a variety of phenomena in the physical andnaturalsciences[1,2,3,4,5,6,7,8,9,10,11]. Alsointhemodelingofbiological systems time delays occur which can be modeled using DDEs.BC7 use of this large number of applications it is of special interest to develop a simulation tool for DDEs. In previous work of Feldstein and Neves [1] high-order methods for the integration of DDEs with time and state dependent time delays have been derived. In this paper we concentrate on the numerical implementation of these methods using the C++ programming language where the class concept will be presented. The analysis of dicretization errors will show high accuracy while simulation results show excellent e#ciency of our implementation. We consider time delay di#erential equations with state vector x(t)=(x 1 (t), ..., x n (t)) T and state space representation x i (t)=f i (t, x(t),x(# 1 (t, x(t))),...,x(# r (t, x(t)))) for t [t 0 ,t e ] ,i=1, ..., n (1) with r retarding functions # j (t, x(t)) [t 0 ,t e ],j =1, ..., r (2) # Cor79 onding author Phone ++49 731 50-26323, Fax ++49 731 50-26301, Email frank.lehn@ chnik.uni-ulm.de which are allowed to depend on time and state. The initial value problem is given by an initial function x(t)=#(t)fort t 0 (3) which describes the history of th..