Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
BACKGROUND: The insecticide chlordecone was extensively used in the French West Indies to control banana root borer. Its persistence in soils has led to the widespread pollution of the environment, and human beings are still exposed to this chemical. Chlordecone has been shown to impair neurological and behavioural functions in rodents when exposed gestationally or neonatally. OBJECTIVES: The aim of the study was to evaluate the impact of prenatal and postnatal exposure to chlordecone on the cognitive, visual, and motor development of 7-month-old infants from Guadeloupe. METHODS: Infants were tested at 7 months (n=153). Visual recognition memory and processing speed were assessed with the Fagan Tests of Infant Intelligence (FTII), visual acuity with the Teller Acuity Card, and fine motor development with the Brunet-Lezine. Samples of cord blood and breast milk at 3 months (n=88) were analyzed for chlordecone concentrations. Postnatal exposure was determined through breast feeding and frequency of contaminated food consumption by the infants. RESULTS: Cord chlordecone concentrations in tertiles were associated with reduced novelty preference on the FTII in the highly exposed group (β=-0.19, p=0.02). Postnatal exposure through contaminated food consumption was marginally related to reduced novelty preference (β=-0.14, p=0.07), and longer processing speed (β=0.16, p=0.07). Detectable levels of chlordecone in cord blood were associated with higher risk of obtaining low scores on the fine motor development scale (OR=1.25, p<0.01). CONCLUSION: These results suggest that pre- and postnatal low chronic exposure to chlordecone is associated with negative effects on cognitive and motor development during infancy.
ISSN: 0013-9351

hal-00875939
https://hal.archives-ouvertes.fr/hal-00875939
DOI : 10.1016/j.envres.2012.07.006
PUBMED : 22910562

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Several studies suggest that exposure to organophosphate insecticides (OP) during pregnancy impairs neurodevelopment in children. OBJECTIVES: We evaluated associations between biomarkers of prenatal and postnatal OP exposure and cognitive function of 6-year-olds in a French longitudinal birth cohort. METHODS: In 2002-2006, the PELAGIE mother-child cohort enrolled pregnant women from Brittany. For a random subcohort, we measured nonspecific dialkylphosphate metabolites (DAP) of OP in one maternal urine sample, collected before 19 weeks' gestation, and in one urine sample collected from their 6-year-old children. Six subtests of the Wechsler Intelligence Scale for Children-4th edition (WISC-IV) was administered at 6 years to evaluate cognitive function (n=231). Linear regression models controlling for factors including maternal intelligence and the Home Observation for Measurement of the Environment score were used. RESULTS: WISC-IV scores were not significantly associated with prenatal or childhood total DAP metabolites. WISC verbal comprehension score was significantly higher in association with the highest maternal urinary concentrations of diethylphosphate metabolites (DE) (5.5; 95% CI: 0.8, 10.3 for extgreater 13.2 nmol/L versus extlessLOQ), while WISC working memory score was significantly lower in association with the highest urinary concentrations of DE metabolites at age 6 years (-3.6; 95% CI: -7.8, -0.6 for extgreater 11.1 nmol/L versus extlessLOD). CONCLUSION: This study found no evidence that prenatal OP exposure adversely affected cognitive function in 6-year-olds, perhaps because of the higher population's socioeconomic status than in previous studies though other causal and non-causal explanations are also possible. The negative association between WISC score and concurrent DE urinary concentrations requires replication by longitudinal studies investigating childhood OP exposure
Environmental Health Perspectives

hal-01207282
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01207282
DOI : 10.1289/ehp.1409472
PUBMED : 26394442

Éditeur(s) : Jamaica Observer Jamaica Observer ( Kingston, Jamaica )
Résumé : Dr Stephanie McKenzie is an associate professor, English Programme, Grenfell Campus, Memorial University, Newfoundland, Canada.

Droits : Copyright by Creator. Permission granted to University of Florida to digitize and display this item for research and educational uses. Permission to reuse, publish or reproduce this item for purposes other than what is allowed by fair use or other copyright exemptions must be obtained from the copyright holder.
http://ufdc.ufl.edu/AA00025661/00001

Éditeur(s) : HAL CCSD
Résumé : International audience
Pen-based interfaces allow users to interact with the help of a stylus and/or fingers. Thanks to a recognition system, users can execute commands by drawing gestures. Because of the complexity of the software, the set of gesture commands can be very large. Consequently, it becomes difficult for the users to remember all the commands. In this paper we introduce "Semicustomizable gestural commands". The idea is to take into account the commands usage frequency: to facilitate the memorization of the most used commands we leave users the freedom/liberty to define their associated gestures (by) themselves. The remaining gesture commands will be automatically generated on the base of the defined gestures according to their hierarchical categorization. Several comparative tests demonstrate that this new approach improved the progressive memorization of the gestural commands.
ICFHR 2012 - International Conference on Frontiers in Handwriting Recognition
Bari, Italy

hal-00708750
https://hal.inria.fr/hal-00708750
https://hal.inria.fr/hal-00708750/document
https://hal.inria.fr/hal-00708750/file/ICFHR_LI_IEEE.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Chlordecone is a persistent organochlorine pesticide that was used in the French West Indies until the early 1990s for banana weevil borer control. Human exposure to this chemical in this area still occurs nowadays due to consumption of contaminated food. Although adverse effects on neurodevelopment, including tremors and memory deficits, have been documented in experimental studies conducted with rodents exposed during the gestational and neonatal periods, no study has been conducted yet to determine if chlordecone alters child development. This study examines the relation of gestational and postnatal exposure to chlordecone to infant development at 18 months of age in a birth-cohort of Guadeloupean children. In a prospective longitudinal study conducted in Guadeloupe (Timoun mother-child cohort study), exposure to chlordecone was measured at birth from an umbilical cord blood sample (n=141) and from a breast milk sample collected at 3 months postpartum (n=75). Toddlers were assessed using an adapted version of the Ages and Stages Questionnaire. Higher chlordecone concentrations in cord blood were associated with poorer fine motor scores. When analyses were conducted separately for boys and girls, this effect was only observed among boys. These results suggest that prenatal exposure to chlordecone is associated with specific impairments in fine motor function in boys, and add to the growing evidence that exposure to organochlorine pesticides early in life impairs child development.
ISSN: 0161-813X

hal-00875907
https://hal.archives-ouvertes.fr/hal-00875907
PUBMED : 23376090
DOI : 10.1016/j.neuro.2013.01.007

Éditeur(s) : Diana Paton Diana Paton ( United Kingdom )
Résumé : From: http://obeahhistories.org/project/ The website is part of the project ‘Spiritual Politics in Caribbean History’, led by Diana Paton and funded by the Arts and Humanities Research Council, which ran from January 2012 to January 2013. Diana Paton is Reader in Caribbean History at the School of History, Classics and Archaeology at Newcastle University. She is the author of No Bond but the Law: Punishment, Race, and Gender in Jamaican State Formation, 1780-1870 (Durham: Duke University Press, 2004), and co-editor, with Pamela Scully, of Gender and Slave Emancipation in the Atlantic World (Durham: Duke University Press 2005). For her publications on obeah and Caribbean religion, please see the publications page. Gemma Romain specialises in researching Caribbean and Black British history. She currently works as a Research Associate for The Equiano Centre, Department of Geography, UCL and also undertakes freelance historical research and public engagement. She was Vera Douie Fellow at the Women’s Library during 2011, documenting interwar Black histories within the collections of the Women’s Library and was previously Leverhulme Early Career fellowship at Newcastle University. Her publications include Connecting Histories: A Comparative Exploration of African-Caribbean and Jewish History and Memory in Modern Britain (Kegan Paul, 2006) and co-edited with David Cesarani, Jews and Ports Cities, 1590-1990: Commerce, Community and Cosmopolitanism (Vallentine Mitchell, 2006). Gemma wrote the initial drafts of most of the text on the website. Maarit Forde worked with Diana on an earlier phase of this project, funded by the Leverhulme Trust. She researched obeah prosecutions and prosecutions under the Shouters Prohibition Ordinance in the Port of Spain Gazette, co-organized the conference that led to the publication of Obeah and Other Powers, and co-edited the book. Previous research on this project has also been funded by Newcastle University and the British Academy.

Droits : Applicable rights reserved.
http://ufdc.ufl.edu/AA00013897/00001

Éditeur(s) : HAL CCSD D-side publications, Evere, Belgium
Résumé : International audience
This article underlines the learning and discrimination capabilities of a model of associative memory based on artificial networks of spiking neurons. Inspired from neuropsychology and neurobiology, the model implements top-down modulations, as in neocortical layer V pyramidal neurons, with a learning rule based on synaptic plasticity (STDP), for performing a multimodal association learning task. A temporal correlation method of analysis proves the ability of the model to associate specific activity patterns to different samples of stimulation. Even in the absence of initial learning and with continuously varying weights, the activity patterns become stable enough for discrimination.
Proceedings of 14 European Symposium on Artificial Neural Networks (ESANN 2006)

hal-00115420
https://hal.archives-ouvertes.fr/hal-00115420
https://hal.archives-ouvertes.fr/hal-00115420/document
https://hal.archives-ouvertes.fr/hal-00115420/file/esann06_HAL.pdf
ARXIV : cs.NE/0611104

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
BACKGROUND: A prospective study of infectious encephalitis was conducted in France in 2007. In total, 253 patients were enrolled with a proven etiological diagnosis for 52%. The cohort of surviving patients with encephalitis was assessed for sequelae and impairment 3 years after enrollment. METHODS: Patients, their family, and general practitioners (GPs) were interviewed by phone to document persisting symptoms, return to work, and past and current leisure activities, with standardized questionnaires. The IQCODE (Informant Questionnaire on Cognitive Decline in the Elderly) was completed with relatives. The global outcome was determined in all patients with the Glasgow outcome scale. RESULTS: In 2010, 20 patients (10%) were unavailable for follow-up, 2 (1%) were excluded, and 18 (9%) had died since hospital discharge. Data were available for 167 survivors and 9 patients whose death was related to the encephalitis. The outcome was favorable in 108 of 176 patients (61%) (71 with complete resolution), 31 (18%) were mildly impaired, 25 (14%) were severely impaired, and 3 (1%) were in a vegetative state. The most frequent symptoms were difficulty concentrating (42%), behavioral disorders (27%), speech disorders (20%), and memory loss (19%). Fifteen of 63 patients (24%) previously employed were still unable to resume work. Long-term outcome was significantly associated with comorbid conditions, age, level of education, and the causative agent of encephalitis. CONCLUSIONS: Most patients with encephalitis experienced a favorable outcome 3 years after hospital discharge. However, minor to severe disability persists in a high number of cases with consequences for everyday life. Physical and mental impairment should be evaluated in all patients with encephalitis, and neuropsychological rehabilitation implemented whenever needed.
ISSN: 1058-4838

hal-00875190
https://hal.archives-ouvertes.fr/hal-00875190
DOI : 10.1093/cid/cis226
PUBMED : 22460967

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Mixtures of polybrominated diphenyl ethers (PBDEs) are present in indoor environments. Studies of the developmental effects of exposure to these chemicals in large prospective mother-child cohorts are required, with data on prenatal exposure and long-term follow-up of the children. We aimed to investigate the relationship between prenatal and childhood exposure to PBDEs and neurodevelopment at the age of six years. We determined the levels of PBDEs and other neurotoxicants in cord blood and dust collected from the homes of children for 246 families included in the PELAGIE mother-child cohort in France. We assessed two cognitive domains of the six-year-old children using the Wechsler Intelligence Scale for Children-IV. Verbal comprehension scores were lower in children from homes with higher concentrations of BDE99 (βDetects < median_vs_NonDetects = −1.6; 95% CI: −6.1, 2.9; βDetects≥median_vs_NonDetects = −5.4; −9.9, −1.0; ptrend = 0.02) and of BDE209 (β2nd_vs₁st_tertile = −1.8; 95% CI: −6.1, 2.5; β3rd_vs₁st_tertile = −3.2; −7.5, 1.2; ptrend = 0.15) in dust, particularly for boys (ptrend = 0.02 and 0.04, respectively). Working memory scores seemed to be lower in children with higher BDE99 concentrations in dust (ptrend = 0.10). No association was observed with cord blood levels of BDE209. Our findings are in agreement with those of four previous studies suggesting adverse cognitive outcomes among children associated with early-life exposure to penta-BDE mixtures, and provide new evidence for the potential neurotoxicity of BDE209. Several countries are in the process of banning the use of PBDE mixtures as flame-retardants. However, these compounds are likely to remain present in the environment for a long time to come
ISSN: 0161-813X

hal-01286255
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01286255
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01286255/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01286255/file/Childhood%20exposure%20to%20polybrominated%20diphenyl-accepted.pdf
DOI : 10.1016/j.neuro.2016.03.002

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : À travers les expositions universelles récentes et passées et plus particulièrement les expositions de Milan 2015 et de Port-au-Prince 1949, nous rappelons que cette pratique touristique du voyage d’agrément dans une grande ville remonte au xixe siècle, elle accompagne les origines de notre tourisme moderne, tout en devenant un instrument de géopolitique et de marketing touristique de première importance pour les villes et les pays hôtes. Les expositions peuvent être considérées comme un levier urbanistique, mais aussi un moyen de faire voyager et de comprendre notre monde à travers un système de représentation des identités locales et mondiales proposant toujours une mise en valeur de la découverte scientifique et de l’expérience culturelle à travers les pavillons nationaux. Ces manifestations géantes reposent sur une mise en scène et en récit à partir d’un thème universel questionnant généralement le concept du développement durable et de l’attractivité touristique renouvelée de la destination. Notre analyse porte sur la plus récente des expositions universelles et une exposition oubliée appartenant à l’aire culturelle des caraïbes permettant de dégager trois dynamiques associant le tourisme de méga-événement et l’utopie des voyages initiatiques, à savoir : les expositions universelles se réinventent et retrouvent un certain succès de fréquentation impliquant une redéfinition des champs et des usages d’une utopie contrariée. Faire voyager est un acte à la fois scénographique et symbolique à travers le pavillon impliquant des artifices et des déclinaisons de plus en plus numériques, la quête de cette pratique durable du voyage se confronte à son héritage et à son souvenir à différentes échelles et temporalités.  
Through the recent and past universal exhibitions and more particularly the world’s fair of Milan 2015 and Port-au-Prince 1949, we recall that this tourist practice of the pleasure trip in a large city dates back to the xixth century, it accompanies the origins of Our modern tourism, while becoming an instrument of geopolitics and tourist marketing of prime importance to cities and host countries. Exhibitions can be seen as an urban lever, but also a way to make travel and understand our world through a system of representation of local and global identities that always emphasizes scientific discovery and cultural experience through the national pavilion. These giant events are based on a staging and narrative based on a universal theme generally questioning the concept of sustainable development and the renewed attractiveness of the destination. Our analysis focuses on the most recent of the universal exhibitions and a forgotten exhibition belonging to the cultural area of the Caribbean, which reveals three dynamics associating mega-event tourism with the utopia of initiatory journeys, namely: reinvent and regain a certain success of frequentation implying a redefinition of the fields and uses of a disrupted utopia; to make travel is an act both scenographic and symbolic through the pavilion involving artifices and more and more digital declensions, the quest for this sustainable practice of travel is confronted with its heritage and its memory at different scales and temporalities.
A través de las exposiciones universales recientes y pasados y, especialmente, la Feria de Milán en 2015 y Puerto Príncipe en 1949, recordamos que esta práctica de turismo de viaje de placer a una gran ciudad se remonta al siglo xix, que acompaña a los orígenes de turismo moderno, mientras que convertirse en un instrumento geopolítico y comercialización del turismo de las principales ciudades y países anfitriones. Las exposiciones pueden considerarse una palanca urbana, sino también una manera de viajar y entender nuestro mundo a través de un sistema de representación de las identidades locales y globales que todavía ofrece el desarrollo de los descubrimientos científicos y la experiencia cultural a través pabellones nacionales. Estas manifestaciones gigantes basados en una puesta en escena y la narrativa de un tema universal en general, cuestionando el concepto de desarrollo sostenible y renovada atractivos turísticos del destino. Nuestro análisis se centra en las últimas exposiciones universales y una exposición olvidado que pertenecen a la zona cultural del Caribe para identificar tres dinámico entre el turismo mega-evento y la utopía de los viajes iniciáticos, a saber: las exposiciones universales reinventar y encontrar un cierto éxito de asistencia que implica una redefinición de campos y utiliza una utopía alterada, para viajar es un acto tanto teatral y simbólico a través del pabellón y declinaciones cada vez más digitales, las la búsqueda de este viaje práctica sostenible se enfrenta a su artificialidad y su memoria en diferentes escalas y marcos de tiempo.
Europe
Caraïbes
Italie
Haïti
France
Milan
Port-au-Prince
New York
Osaka

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.11239
http://journals.openedition.org/etudescaribeennes/11239

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Pyrethroid insecticides are widely used in agriculture and in homes. Despite the neurotoxicity of these insecticides at high doses, few studies have examined whether lower-level exposures could adversely affect children's neurodevelopment. The PELAGIE cohort included 3421 pregnant women from Brittany, France between 2002 and 2006. When their children reached their sixth birthday, 428 mothers from the cohort were randomly selected, successfully contacted and found eligible. A total of 287 (67%) mothers agreed to participate with their children in the neuropsychological follow-up. Two cognitive domains were assessed by the Wechsler Intelligence Scale for Children: verbal comprehension and working memory. Five pyrethroid and two organophosphate insecticide metabolites were measured in maternal and child first-void urine samples collected between 6 and 19 gestational weeks and at 6 years of age, respectively. Linear regression models were used to estimate associations between cognitive scores and urinary pyrethroid metabolite concentrations, adjusting for organophosphate metabolite concentrations and potential confounders. Maternal prenatal pyrethroid metabolite concentrations were not consistently associated with any children's cognitive scores. By contrast, childhood 3-PBA and cis-DBCA concentrations were both negatively associated with verbal comprehension scores (P-trend = 0.04 and P-trend < 0.01, respectively) and with working memory scores (P-trend = 0.05 and P-trend < 0.01, respectively). No associations were observed for the three other childhood pyrethroid metabolite concentrations (4-F-3-PBA, cis-DCCA, and trans-DCCA). Low-level childhood exposures to deltamethrin (as cis-DBCA is its principal and selective metabolite), in particular, and to pyrethroid insecticides, in general (as reflected in levels of the 3-PBA metabolite) may negatively affect neurocognitive development by 6 years of age. Whatever their etiology, these cognitive deficits may be of importance educationally, because cognitive impairments in children interfere with learning and social development. Potential causes that can be prevented are of paramount public health importance
ISSN: 0160-4120

hal-01162374
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01162374
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01162374/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01162374/file/Pyrethroid%20insecticide%20exposure.pdf
DOI : 10.1016/j.envint.2015.05.009

Éditeur(s) : HAL CCSD Elsevier
Résumé : We present the hierarchical matrix (H-matrix) technique combined with the adaptive cross-approximation (ACA) applied to a three-dimensional (3D) elastostatic problem using the boundary element method (BEM). This is used in structural geology and geomechanics for the evaluation of the deformation and perturbed stress field associated with surfaces of displacement discontinuity. Such optimization significantly reduces (i) the time and memory needed for the resolution of the system of equations, but more importantly (ii) the time needed for the post-processing at observation points where the deformation and the perturbed stress field are evaluated. Specifically, it is shown that the H-matrix structure used with the ACA, clearly captures the kernel smoothness during the post-processing stage according to the field point positions, and optimizes the computation accordingly. Combined with the parallelization on multi-core processors, this technique allows intensive computations to be done on personal desktop and laptop computers. Numerical simulations are presented, showing the advantages of such optimizations compared to the standard method.
ISSN: 0955-7997

hal-00561032
https://hal.archives-ouvertes.fr/hal-00561032
DOI : 10.1016/j.enganabound.2009.10.016

Éditeur(s) : HAL CCSD
Résumé : Point processes are often used as spatial or spatio-temporal distribution models of occurrences. In this PhD dissertation, we focus first on Cox processes driven by a hidden process associated with a Dirichlet process. This model corresponds to hidden occurrences influencing the stochastic intensity of observed occurrences. We generalize the notion of "Shot noise Cox process" introduced by M{o}ller and develop its bayesian analysis by a Gibbs sampler combined with a Metropolis-Hastings algorithm. We show that our MCMC method is a reversible jump one. The model takes into account a random number of hidden contributions producing effects on the observed point process intensity. Therefore the parameter space has a variable dimension. We focus the statistical inference on the estimation of the hidden contribution expected value, the hidden contribution expected number, the spatial influence and correlation parameters. The contribution equality test and contribution independence test are proposed. Applications in epidemiology and ecology are shown from extit{Rubus fruticosa} data, extit{Ibicella lutea} data and death number data in counties of Georgia, USA. Two situations are considered with respect to available data~: firstly, the spatial positions of occurrences are observed between several pairs of consecutive dates; secondly, counts are carried out over a fixed time interval in several spatial sampling units. Secondly, we focus on point processes with memory introduced by Kagan, Ogata and Vere-Jones, pioneers in statistical seismology. In fact, spatio-temporal point processes play an important role in the studies of earthquake catalogs since they consist of seismic events with their dates and spatial locations. We studied an ETAS (Epidemic Type Aftershock Sequence) model with time independent background intensity and several triggering functions taking into account previous events. We illustrate our approach with a seismicity study of the Lesser Antilles arc. A comparaison study of Gamma, Weibull, Log-Normal and modified Omori law triggering function models is also carried out. We show that the modified Omori law does not fit the Lesser Antilles seismic data and the best adjusted triggering function is the Weibull model. Consequently, the waiting time between aftershocks is weaker in the Lesser Antilles zone compared to the one in regions with seismicity described by the modified Omori law. In other words, aftershock aggregativity is higher in the Lesser Antilles region. The stochastic background intensity following a Dirichlet process centered on a spatial log-normal process is discussed.
Les processus ponctuels sont souvent utilisés comme modèles de répartitions spatiales ou spatio-temporelles d'occurrences. Dans cette thèse, nous nous intéressons tout d'abord à des processus de Cox dirigés par un processus caché associé à un processus de Dirichlet. Ce modèle correspond à des occurrences cachées influençant l'intensité stochastique des occurrences observées. Nous généralisons la notion de " Shot noise Cox process " introduite par Moller et développons le traitement bayésien par un échantillonneur de Gibbs combiné à un algorithme de Metropolis-Hastings. Nous montrons que cette méthode MCMC est à sauts réversibles. Le modèle prend en compte, en effet, un nombre aléatoire de contributions cachées influençant l'intensité du processus ponctuel observé donc a un espace paramétrique de dimension variable. Nous focalisons l'inférence statistique sur l'estimation de la valeur espérée de chaque contribution cachée, le nombre espéré de contributions cachées, le degré d'influence spatiale de ces contributions et leur degré de corrélation. Le test d'égalité des contributions et celui de leur indépendance sont ainsi développés. L'utilité en épidémiologie et en écologie est alors démontrée à partir de données de Rubus fruticosa, Ibicella lutea et de mortalité dans les cantons de Georgia, USA. En termes de données observées, deux situations sont considérées: premièrement, les positions spatiales des occurrences sont observées entre plusieurs paires de dates consécutives; deuxièmement, des comptages sont effectués, au cours d'une période fixée, dans des unités d'échantillonnage spatiales. D'autre part, nous nous intéressons aux processus ponctuels à mémoire introduits par Kagan, Ogata et Vere-Jones, précurseurs de la statistique sismologique. En effet, les processus ponctuels spatio-temporels ont une place importante dans l'étude des catalogues sismiques puisque ces derniers sont généralement constitués d'événements sismiques datés et géo-référencés. Nous avons étudié un modèle ETAS (Epidemic Type Aftershock Sequence) avec une intensité d'arrière-plan indépendante du temps et plusieurs fonctions déclenchantes permettant d'intégrer les événements antérieurs récents. Cette approche est utilisée pour étudier la sismicité de l'arc des Petites Antilles. Une étude comparative des modèles Gamma, Weibull, Log-Normal et loi d'Omori modifiée pour les fonctions déclenchantes est menée. Nous montrons que la loi d'Omori modifiée ne s'ajuste pas aux données sismiques des Petites Antilles et la fonction déclenchante la plus adaptée est le modèle de Weibull. Cela implique que le temps d'attente entre répliques dans la zone des Petites Antilles est plus faible que celui des régions à sismicité décrite par la loi d'Omori modifiée. Autrement dit, l'agrégation des répliques après un événement majeur est plus prononcée dans la zone des Petites Antilles. La possibilité d'inclure une intensité d'arrière-plan suivant un processus de Dirichlet centré sur un processus spatial log-gaussien est discutée.
https://tel.archives-ouvertes.fr/tel-00841146

Droits : info:eu-repo/semantics/OpenAccess
NNT : 2012AGUY0555
tel-00841146
https://tel.archives-ouvertes.fr/tel-00841146
https://tel.archives-ouvertes.fr/tel-00841146/document
https://tel.archives-ouvertes.fr/tel-00841146/file/these_VALMY.pdf

Résumé : Les processus ponctuels sont souvent utilisés comme modèles de répartitions spatiales ou spatio-temporelles d'occurrences Dans cette thèse, nous nous intéressons à des processus de Cox dirigés par un processus caché associé à un processus de Dirichlet. Ce modèle correspond à des occurrences cachées influençant l'intensité stochastique des occurrences observées. Nous généralisons la notion de Shot noise Cox process et développons le traitement bayésien. Nous focalisons l'inférence statistique sur l'estimation de la valeur espérée de chaque contribution cachée, leur nombre espéré, degré d'influence spatiale et degré de corrélation L'utilité en épidémiologie et en écologie est démontrée à partir de données de Rubus fruticosa, lbicella lutea et de mortalité dans les cantons de Georgie, USA. En termes de données observées, deux situations sont considérées: d'abord, les positions spatiales des occurrences sont observées entre plusieurs paires de dates consécutives; puis, des comptages sont effectués dans des unités d'échantillonnage spatiales. D'autre part, nous nous intéressons aux processus ponctuels à mémoire introduits par Kagan, Ogata et Vere-Jones. En effet, les processus ponctuels ont une place importante dans l'étude des catalogues sismiques. Nous avons étudié un modèle Epidemie Type Aftershock Sequence avec une intensité d'arrière-plan indépendante du temps et plusieurs fonctions déclenchantes permettant d'intégrer les événements antérieurs récents. Cette approche est utilisée pour étudier la sismicité des Petites Antilles. Une étude comparative des modèles Gamma, Weibull, Log-Normal et loi d'Omori modifiée pour les fonctions déclenchantes est menée.
Point processes are often used as spatial or spatio-temporal distribution models of occurrences. In this Phd dissertation, we focus first on Cox processes driven by a hidden process associated with a Dirichlet process. This model corresponds to hidden occurrences influencing the stochastic intensity of observed occurrences. We generalize the notion of Shot noise Cox process and develop its bayesian analysis. We focus the statistical inference on the estimation of the hidden contribution expected value, the hidden contribution expected number, the spatial influence and correlation parameters. Applications in epidemiology and ecology are shown from Rubus fruticosa data, Ibicella lutea data and death number data in counties of Georgia, USA. Two situations are considered with respect to available data: firstly, the spatial positions of occurrences are observed between several pairs of consecutive dates; secondly, counts are carried out over a fixed time interval in several spatial sampling units. Secondly, we focus on point processes with memory intr oduced by Kagan, Ogata and Vere-Jones. Spatio-temporal point processes play an important role in the studies of earthquake catalogs since they consist of seismic events with their dates and spatial locations. We studied an Epidemic Type Aftershock Sequence model with time independent background intensity and several triggering functions taking into account previous events. We illustrate our approach with a seismicity study of the Lesser Antilles arc. A comparaison study of Gamma, Weibull, Log-Normal and modified Omori law triggering function models is also carried out

http://www.theses.fr/2012AGUY0555/document