1,040 research outputs found
Impact of Obstacles on the Degree of Mobile Ad Hoc Connection Graphs
What is the impact of obstacles on the graphs of connections between stations
in Mobile Ad hoc Networks? In order to answer, at least partially, this
question, the first step is to define both an environment with obstacles and a
mobility model for the stations in such an environment. The present paper
focuses on a new way of considering the mobility within environments with
obstacles, while keeping the core ideas of the well-known Random WayPoint
mobility model (a.k.a RWP). Based on a mesh-partitioning of the space, we
propose a new model called RSP-O-G for which we compute the spatial
distribution of stations and analyse how the presence of obstacles impacts this
distribution compared to the distribution when no obstacles are present.
Coupled with a simple model of radio propagation, and according to the density
of stations in the environment, we study the mean degree of the connection
graphs corresponding to such mobile ad hoc networks
Evaluation des informations préopératoires et du consentement signé en chirurgie pédiatrique
1. Abstract
Au XXème siècle la médecine a passablement évolué et la question de l'implication du patient dans le processus de décision thérapeutique devient petit à petit une nécessité. La théorie du consentement éclairé apparaît en Suisse à la fin des années 70 et l'information du patient devient un thème incontournable. C'est dans cette perspective que le formulaire de consentement vient progressivement s'imposer.
Dans la première partie de ce travail, nous avons cherché à mettre en évidence qu'elles pouvaient être les directives éthiques et juridiques en matière de formulaire de consentement en vue d'une intervention chirurgicale. Pour que ce formulaire soit validé, il doit être accompagné d'une information claire et appropriée afin obtenir un consentement libre et éclairé du patient tant du point de vue éthique que juridique.
Dans la deuxième partie, nous nous sommes intéressés à l'usage et l'utilisation du formulaire de consentement employé au sein du service de chirurgie pédiatrique au CHUV et à l'HEL. Afin d'en avoir un bon reflet, nous avons soumis un questionnaire à des chirurgiens cadres ou chefs de cliniques du service de chirurgie pédiatrique. Ce questionnaire se base sur des questions soulevées par la littérature traitant du sujet ainsi que sur l'article 21 de la loi sur la Santé publique du canton de Vaud qui dit, en résumé, que le minimum requis est le droit à l'information afin de donner valablement un consentement. Il est composé de trois parties. Dans la première partie, il en ressort qu'en règle générale les chirurgiens s'accordent sur la définition du formulaire de consentement. Ils sont dans l'ensemble satisfaits du formulaire en vigueur et n'en modifieraient pas la structure. Dans la deuxième partie, la signature du formulaire est vue comme une obligation mais la raison de cette obligation n'a pas la même signification pour chacun et les avis divergent quant il s'agit de savoir qui cela protège. Dans la troisième partie, ils s'accordent tous sur le contenu de l'information jugé nécessaire à donner aux parents des futurs opérés.
En conclusion, les chirurgiens pédiatres semblent globalement satisfaits du formulaire
actuel et peu le modifieraient. Nous trouvons important de mentionner que peu soulèvent le fait que le principal concerné par l'intervention est l'enfant et que son avis n'est pas toujours sollicité. A l'avenir, il sera important d'impliquer l'enfant dans cette démarche tout en tenant compte de son degré de maturité
GraphStream: A Tool for bridging the gap between Complex Systems and Dynamic Graphs
The notion of complex systems is common to many domains, from Biology to
Economy, Computer Science, Physics, etc. Often, these systems are made of sets
of entities moving in an evolving environment. One of their major
characteristics is the emergence of some global properties stemmed from local
interactions between the entities themselves and between the entities and the
environment. The structure of these systems as sets of interacting entities
leads researchers to model them as graphs. However, their understanding
requires most often to consider the dynamics of their evolution. It is indeed
not relevant to study some properties out of any temporal consideration. Thus,
dynamic graphs seem to be a very suitable model for investigating the emergence
and the conservation of some properties. GraphStream is a Java-based library
whose main purpose is to help researchers and developers in their daily tasks
of dynamic problem modeling and of classical graph management tasks: creation,
processing, display, etc. It may also be used, and is indeed already used, for
teaching purpose. GraphStream relies on an event-based engine allowing several
event sources. Events may be included in the core of the application, read from
a file or received from an event handler
DynamicScore: a Novel Metric for Quantifying Graph Dynamics
This study introduces a new metric called ''DynamicScore'' to evaluate the
dynamics of graphs. It can be applied to both vertices and edges. Unlike
traditional metrics, DynamicScore not only measures changes in the number of
vertices or edges between consecutive time steps, but also takes into account
the composition of these sets. To illustrate the possible contributions of this
metric, we calculate it for increasing networks of preferential attachment
(Barab{\'a}si-Albert model) and Edge-Markovian graphs. The results improve our
understanding of the dynamics inherent in these generated evolving graphs
Dynamic Graphs Generators Analysis : an Illustrative Case Study
In this work, we investigate the analysis of generators for dynamic graphs,
which are defined as graphs whose topology changes over time. We introduce a
novel concept, called ''sustainability,'' to qualify the long-term evolution of
dynamic graphs. A dynamic graph is considered sustainable if its evolution does
not result in a static, empty, or periodic graph. To measure the dynamics of
the sets of vertices and edges, we propose a metric, named ''Nervousness,''
which is derived from the Jaccard distance.As an illustration of how the
analysis can be conducted, we design a parametrized generator, named D3G3
(Degree-Driven Dynamic Geometric Graphs Generator), which generates dynamic
graph instances from an initial geometric graph. The evolution of these
instances is driven by two rules that operate on the vertices based on their
degree. By varying the parameters of the generator, different properties of the
dynamic graphs can be produced.Our results show that in order to ascertain the
sustainability of the generated dynamic graphs, it is necessary to study both
the evolution of the order and the Nervousness for a given set of parameters
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