La modélisation des événements et de leurs propriétés temporelles concerne des types variés d’utilisateurs et de communautés scientifiques. Nous nous plaçons dans le cadre du paradigme Objet et construisons un méta modèle opérationnel servant de représentation pivot, indépendante du métier pour représenter des événements composites avec leurs propriétés structurelles et temporelles. Le méta modèle PTOM (Periodic Temporal Occurrence Metamodel) prend en compte l’expression de contraintes structurelles sur les événements, ou géométriques, topologiques et relationnelles sur la temporalité de leurs occurrences. Il privilégie la représentation en intension (vs extension) des occurrences d’événements périodiques. PTOM étend la norme ISO 19108 et s’adapte aux standards EventsML G2 et iCalendar. Sur un plan théorique, nous étendons les algèbres d’intervalles d’ALLEN et de LIGOZAT, et proposons un système de relations topologiques entre intervalles non convexes (ALLEN*) dont nous étudions les propriétés. Ces résultats sont intégrés dans PTOM. La première application de PTOM est la spécification de la sémantique du calendrier grégorien. Les éléments calendaires sont réintroduits en tant qu’événements périodiques dans PTOM, ce qui renforce son pouvoir expressif. PTOM a été mis en œuvre lors d’un projet ANR sur des corpus d’événements journalistiques (agences de presse) concernant les loisirs et la culture. L’Ingénierie Dirigée par les Modèles a été utilisée pour la conception et l’exploitation de PTOM. Cela permet de gérer la complexité, d’assurer la maintenabilité et la cohérence de l’ensemble et enfin, de générer automatiquement des interfaces pour les pourvoyeurs ou utilisateurs de données. / Modelling events with their temporal properties concerns many users and scientific communities. We adopted the Object paradigm and designed an operational metamodel which stands as a pivot business independent representation for composite events accompanied with their structural and temporal properties. PTOM metamodel (Periodic Temporal Occurrence Metamodel) accounts for structural constraints upon events and geometric, topologic or relational constraints upon their temporal occurrences. It gives prominence to intensional representations of periodic events occurrences vs extensional ones. PTOM extends ISO 19108 standard and fits EventsML G2 and iCalendar. From a theoretical viewpoint, we extend ALLEN’s and LIGOZAT’s interval algebras and propose a special set of topological relations between non convexintervals (ALLEN*), and study its properties. These results are part of PTOM. The first application of PTOM results in a specification of the Gregorian calendar semantics. Calendar elements are reinserted as periodic events in PTOM thus enhancing its expressiveness. PTOM was also experimented upon a corpus of journalistic (press agencies) events dedicated to leisure and culture at the occasion of an ANR project. Model Driven Engineering was extensively used for PTOM design and use.It allows to manage complexity and to ensure maintainability, consistency and eventually can automatically generate data provider or end user interfaces as well.

Summarized the results of previous studies, the body size of Niviventer coxingi seemed to be correlated with altitude. For more exact evidence, geographic variations of body lengths and appendage sizes among areas were examined. Moreover, Freckleton et al. (2003) indicated that phylogenetic relationships may affect the results of one¡¦s study while variation of body size is discussed. Therefore, the phylogeographic variation among different areas was also examined in this study. The body lengths of N. coxingi in higher altitude (Fong-gang, 1700 m) were shorter than in lower altitude (Shan-ping 700 m). Body lengths of N. coxingi in Shan-ping were longer than other areas but Wu-shih-kang; and N. coxingi in Fong-gang were longer than those in Wu-tou Mountain; but no significant differences were found among other areas. No significant differences were found in appendage sizes but hind-foot length. Significant differences of the hind-foot length were only found between Shan-ping which had the longest hind-foot lengths in average and those in Wu-tou Mountain which had the shortest. No correlations were found between altitudes and the body length or appendage sizes of N. coxingi. The phylogenetic relationships based on D-loop region of N. coxingi were reconstructed by neighbor-joining, maximum parsimony and maximum-likelihood methods. An N. culturatus was used to be an outgroup. All three trees represented similar patterns. Although some individuals from neighborhood grouped together, some individuals from the same area represented distantly. Moreover, many branches represented in the root of the consensus trees because of the low bootstrap value. The results revealed the geographic variations did not correlated with their phylogenetic relationships and the heat conservation/ dissipation mechanism, which was the traditional explanation of Bergmann¡¦s rule, was not appropriate for N. coxingi, either.

Bergmann’s and Allen’s rule suggest that for the same species individuals found further north, tend to have larger body sizes and smaller appendages compared to individuals further south, respectively, due to constraints for thermal regulation. This has shown especially true for birds and mammals.  In this paper, I test to see if global warming has led to a change in morphology for birds, i.e. body weight and wing size. We use year as a proxy for temperature as global warming has on average lead to an increase in the earth’s surface temperature over the last century with most of the change occurring since the 1980’s.  To test the hypothesis, I gathered data of male, young of the year birds during autumn migration for a select number of species with different wintering strategies, i.e. resident to long-distance migration. This data came from two Swedish bird observatories where standardized wing and weight measurements have been collected since 1986, coincident with the observed climate warming. The results of this study show that during this period, changes in body mass and wing length did not support the hypothesis that global warming has had a broad impact on the morphology of birds. Given that these results contradict that of other studies, analysis from species across a much wider latitudinal breadth of Europe, including, additional species and different age and sex classes should be investigated.

No description available.

Récemment, plusieurs applications, dans lesquelles différentes entités interagissent dans un environnement dynamique, soulignent l’intérêt de l’utilisation des architectures multi-agents. Ces architectures offrent, dans ce cadre, un certain nombre d’avantages, tels que l’autonomie, la réactivité et la capacité de prise de décision. Elles manquent cependant de capacité sociale et de connaissances sur son environnement, notamment lorsqu’il s’agit d’un environnement dynamique. En effet, quand un agent interagit avec le monde réel, il doit prendre en compte les évènements qui peuvent survenir tout en considérant centaines contraintes telles que le temps et l’espace. En outre, les agents doivent faire face à l’incertitude liée aux applications réelles afin de fournir une représentation fidèle du monde réel. Dans le cadre de cette thèse, nous proposons un modèle formel de recommandation des plans qui améliore le processus de prise de décision des agents dans un environnement spatio-temporel et incertain. Pour formaliser les comportements cognitifs des agents dans notre système nommé CARS, en anglais ``Cognitive Agent-based Recommender System '', nous avons étendu l’architecture BDI qui se base sur le modèle `` Croyance-Désir-Intention'' pour prendre en compte les différents contextes liés à des applications réelles en particulier le contexte social. Par ailleurs, nous avons également utilisé la théorie possibiliste afin de considérer l’incertitude dans l’état motivationnel d’un agent (c’est à dire ses croyances, désirs, objectifs ou intentions). Pour répondre aux besoins des applications réelles, tels que les systèmes de recommandation relatives au trafic et navigation, nous proposons une représentation spatiotemporelle des croyances et des intentions d’un agent. Cette représentation permettra l’anticipation de certaines intentions, de manière à recommander un plan qui sera optimal pour un utilisateur. Compte tenu l’incomplétude/l’imprécision liée aux données spatiotemporelles, nous avons étendu le modèle proposé pour raisonner avec des croyances et intentions floues. Une évaluation du modèle proposé a été menée en utilisant une simulation multi-agent, dans un scenario réel de circulation routière. Cette simulation a offert un environnement virtuel qui a mis en lumière, après avoir testé les différentes fonctionnalités du modèle, les principaux points forts ainsi que leslacunes liées à l’architecture multi-agents proposée. / Recently, many real-world applications where different entities interact in a dynamic environment, consider the use of agents in their architectures due principally to their autonomy, reactivity and decision-making abilities. Though these systems can be made intelligent, using Artificial Intelligence (AI) techniques, agents still lack of social abilities and have limited knowledge of their environment and in particular when it comes to a dynamic environment. In fact, when operating in the real world, agents need to deal with unexpected events considering both changes in time and space. Moreover, agents must face the uncertainty, which pervades real-world scenarios in order to provide an accurate representation of the world. In this thesis, we introduce and evaluate a formal framework for recommending plans to agents in the decision making process, when they deal with uncertain spatio-temporal information. The agent-based architecture we propose to address this issue, called CARS (Cognitive Agent-based Recommender System), has been designed by extending the well-known Belief-Desire-Intention (BDI) architecture to incorporate further capabilities to support reasoning with different types of contextual information, including the social context. Uncertainty on the agent's beliefs, desires and intentions is modeled using possibility theory. To meet the requirements of real-world applications, e.g., traffic and navigation recommendation systems, we define a spatio-temporal representation of the agents' beliefs and intentions. Using such a formal framework, anticipatory reasoning about intentional dynamics can be performed with the aim to recommend an optimal plan to a certain user. Since spatio-temporal data is often considered as incomplete and/or vague, we extended the formal framework with a fuzzy representation of spatio-temporal beliefs and intentions. The framework is evaluated through an Agent Based Simulation (ABS) in a real-world traffic scenario. This ABS allowed us to create a virtual environment to test the impact of the different features of our framework as well as to evaluating the main strengths and weaknesses of the proposed agent architecture.

There is a revolutionary change in the world of work that impacts on the individual, work and society. The future of work suggests flexibility, boundary less communities and change in work, as we know it today. As the world of work changes from a worker intensive industrial society towards an automated information society, the retention of technological advantages e.g., human, intellect and knowledge capital is no longer assured. Employers struggle to retain their valuable high technology employees due to a general shortage of experienced candidates and aggressive recruitment tactics by others in the high technology arena. The purpose of this study is to investigate specific retention factors that induce organisational commitment and can thus increase the retention of high technology employees. High technology industries operate in volatile market and experience accelerating growth and rates of change. High technology employees are educated, have a strong preference for independence and hold a large portion of the organisation's intellectual capital. A core belief in human resources is to retain and develop employees to obtain a competitive advantage. In order to retain these valuable employees it has become necessary for organisations to transform from using an employee controlling to a more employee commitment driven strategy. To gain employees' commitment to the organisation and increase retention, the employer needs to identify which retention factors induce organisational commitment. Compensation, job characteristics, training and development opportunities, supervisor support, career opportunities and work/life policies were identified as the top six retention factors in the content analysis done on high technology literature. Organisational commitment has been defined as a mindset, which ties the individual to the organisation. Different forms and foci of organisational commitment are discussed with the approach developed by Meyer and Allen's three component model (1991). The consequences of organisational commitment benefit the organisation in terms of increased job performance, intention to stay, increase in attendance, loyalty, decrease in turnover, greater creativity, more co-operation (particularly across discipline specialities), more volunteerism and more time devoted to productive work on behalf of the organisation. This study focused on a 100% South African owned telecommunications company based in the Gauteng province. A questionnaire was developed and a population of 94 telecommunications professionals, technicians and associated professionals were selected to investigate the influence of various identified retention factors on organisational commitment. The statistical analysis of the data culminated in a regression analysis that measured the significance and the strength of the relationship between the identified retention factors and organisational commitment. The main conclusions were that compensation, job characteristics, supervisor support and work/life policies were significantly related to organisational commitment. On the other hand, in this study training, development and career opportunities were not related. High technology organisations are not just interested in the retention of employees but also creating a mutually beneficial interdependence with employees. The identified retention factors might serve as a means to demonstrate the organisation's support for, or commitment to, their employees and in turn cultivate a reciprocal attachment by employees. Employees' organisational commitment is related to their belief that the identified retention factors are motivated by the desire to retain good employees and to be fair in the treatment of employees. Future research needs are discussed. / Dissertation (MCom (Human Resources Management))--University of Pretoria, 2004. / Human Resource Management / unrestricted