Thèses sur le sujet « Risques multiples »
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Scarmure, Patrick. « Essais sur la demande d'assurance en présence de risques multiples ». Toulouse 1, 1992. http://www.theses.fr/1992TOU10036.
Texte intégralWe characterize in this research the properties of optimal insurance coverage under multiple sources of insurable risks. The idea is that the insurance decision about a particular risky asset can not be made without considering the other insurable risky assets of the portfolio. We first consider the effect of a better diversification of the total property at risk on the demand for insurance. We show that the importance of the diversification effect depends on the presence of a positive or a negative correlation between the risky assets as well as the homogeneity of these risky assets. Finally, we analyze how a compulsory insurance requirement or the presence of uninsurable risks affects the non-constrained demand for insurance
Loschmann, Ronald. « Contribution à l'élaboration d'une méthode d'analyse prévisionnelle de la sécurité de systèmes à risques multiples : application à un site industriel urbain ». Aix-Marseille 3, 2002. http://www.theses.fr/2002AIX30050.
Texte intégralThe work presented in this thesis is in the scope of organisational safety and knowledge engineering. It contributes to the elaboration of a computerized method for the provisional analysis on safety of Urban Industrial Sites (UIS). The method consists in foreseeing the critical behaviour of UIS, given accident scenarios, by means of an hybrid model simulator. The simulator rests on the UIS and the accident conceptual models, elaborated from ontological studies and the KOD method. The UIS model renders an account of technical, human and organisational aspects. The accident model, inspired from the J. Dumaine model, permits to assess the consequences of the three industrial accident types : the release of toxic substances, fire and explosion. The conceptual models are formalized using UML-RT extended for hybrid systems and implemented with Anylogic. Our experimentations were carried out on the UIS of Marseilles St Menet
Bastit, Félix. « An economic approach to multiple risks in forests ». Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0256.
Texte intégralForests are a major natural resource in Europe. It covers 33% of the territory, accounts for 0.2% of European GDP and provides 3.6 million jobs. European forests are also the source of numerous ecosystem services such as wood production and carbon storage. However, they are subject to numerous hazards: wildfires, windstorms, droughts, insect outbreaks, etc., which threaten the provision of these services. In addition, climate change is increasing the probability and intensity of these hazards, as well as their interactions. From an economic point of view, two main risks arise from the occurrence of natural hazards: a production risk (wood and carbon storage) and a market risk (price volatility).The literature has focused on wood production risk at stand scale, since this is the relevant scale for forest management decisions. However, this is not the right scale for modeling large-scale natural hazards, nor for modeling the effects of price changes. In this thesis, we have therefore decided to work at several different spatial scales: stand, regional, country and continent. Furthermore, potential interactions between natural hazards have rarely been considered, even though they could lead to phenomena of unprecedented magnitude. Price risk has also been studied extensively in the literature, but generally independently of production risk, even though there is a strong correlation between the two, as demonstrated by price falls after major historical storms. In this thesis, we will try to take this correlation into account.This work is divided into four parts. Firstly, a review of the forest economics literature shows the current limitations and the most promising avenues of research. The main conclusion of this work is that natural hazards are generally considered independent in forest economics, whereas ecological models are more inclusive.In response to this, in the second chapter we decided to abandon the classical forest economics model to study the resilience of a self-sufficient regional timber market to generic hazards of catastrophic magnitude. We have studied the levels of hazards and acceptable return times to ensure the stability of long-term market equilibrium.In the third chapter, we applied this model more precisely to the French forestry sector, using a recursive partial equilibrium model (French Forest Sector Model). A spatially explicit simulation module for windstorms and insect outbreaks was developed. This enabled us to establish results on the strategies of the various economic actors in the sector in the event of the occurrence of interacting natural hazards. We also studied the desirable public policies to be implemented in anticipation of the occurrence of major storms. We then discussed the robustness of public policies to mitigate climate change, such as intended nationally determined contributions from the Paris Agreement, facing natural disturbances.In the final chapter, the potential cost of climate change based on wood production at European level was estimated, including the four economically significant tree species in Europe. We have shown that losses due to catastrophic natural hazards are likely to increase significantly as a result of climate change, but that some of these losses will be offset by gains in forest productivity. These effects are, however, spatially very heterogeneous, leading to winners and losers, for whom climate change mitigation strategies could prove all the more complicated to implement in the event of a reduction in their forest carbon sink
Herquelot, Eleonore. « Facteurs de risque professionnels des troubles musculo−squelettiques aux coudes et aux genoux ». Thesis, Versailles-St Quentin en Yvelines, 2015. http://www.theses.fr/2015VERS004V/document.
Texte intégralMusculoskeletal disorders (MSDs) are a leading cause of absenteeism from work. In addition to their major economic impact, musculoskeletal disorders have important consequences on individuals with the persistence of pain, disability and potential job loss. Many occupational exposures were highlighted to explain these symptoms, but certain relationships between occupational exposures and MSDs should be examined further.The aim of this thesis is to investigate the association between occupational exposures, especially biomechanical exposures, and elbow or knee MSDs. The elbow MSDs are studied with the prevalence of symptoms and lateral epicondylitis, and the incidence of lateral epicondylitis. The incidence of knee pain is examined according to its duration.The methodologies and theories appropriate to this type of work is briefly presented - a section focuses on the causal diagrams and methods of handling missing data.The population used is a cohort of 3710 subjects representative of the French workforce. Subjects were selected from workers undergoing a mandatory annual health examination between 2002 and 2005 and were followed between 2007 and 2010. For each phase of the study, a self-administered questionnaire on working conditions was completed and a clinical examination was performed in order to evaluate the presence of musculoskeletal disorders. In conclusion, repetitive movements involving the joints studied such as wrist-twisting, flexion/extension of the elbows or kneeling are associated with MSDs. The notion of force, such as load handling and physical exertion, and the notion of repetitive tasks are also identified as predictors of subsequent MSDs
Kariche, Jugurtha. « Rôle des transferts multiples de contraintes, déficit de sismicité et caractéistiques physiques des ruptures sismiques ». Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAH015/document.
Texte intégralThis thesis consists in six chapters that describe the characteristics of active tectonics and stress transfer related to major earthquakes. The aim of this thesis is a better estimate of the seismic hazard and risk in northern Algeria and Morocco. After an introduction, Chapter II presents the methodology adopted for the development of stress transfer models. Chapter III deals with the interaction between faults in the Algerian Tell Atlas. Chapter IV develops the aspects of stress transfer and poroelastic deformation in the Rif and the Alboran Sea. Chapter V presents a large development of the poroelastic deformation and the physical characteristics of seismic ruptures. Chapter VI consists of a general conclusion with presentation of the main results including the perspectives and futur researchs
Zara-Meylan, Valérie. « Modalités de gestion du milieu temporel dans une conduite de processus multiples en situation dynamique : une recherche dans des entreprises horticoles ». Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00795233.
Texte intégralBani-Mustafa, Tasneem. « Multi-Hazards Risk Aggregation Considering the Trustworthiness of the Risk Assessment ». Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC096.
Texte intégralThis PhD thesis addresses the problem of Multi-Hazards Risk Aggregation (MHRA), which aims at aggregating the risk estimates from Probabilistic Risk Assessment (PRA) models for the different contributors. The current practice of MHRA is based on a simple arithmetic summation of the risk estimates. However, the risk estimates are obtained from PRA models that have different degrees of trustworthiness, because of the different background knowledge they are based on. Ignoring this difference in MHRA could lead to misleading results for Decision-Making (DM). In this thesis, a structured framework is proposed to assess the level of trustworthiness, which risk assessment results are based on and to integrate it in the process of MHRA. The original scientific contributions are: (i) Factors contributing to the trustworthiness of risk assessment outcomes are identified and their criticalities are analyzed under different frameworks, to understand their influence on the risk results; (ii) An integrated hierarchical framework is developed for assessing the trustworthiness of risk analysis, based on the identified factors and related attributes; (iii) A reduced order model-based method is proposed to efficiently evaluate the trustworthiness of risk assessment in practice. Through the reduced-order model, the proposed method can limit the number of elements considered in the original risk assessment; (iv) A technique that combines Dempster Shafer Theory and the Analytic Hierarchy Process (namely, DSTAHP) is applied to the developed framework to assess the trustworthiness by a weighted average of the attributes in the framework: the AHP method is used to derive the weights of the attributes and the DST is used to account for the subjective uncertainty in the experts’ judgments for the evaluation of the weights; (v) A MHRA technique is developed based on Bayesian model averaging, to overcome the limitations of the current practice of risk aggregation that neglects the trustworthiness of the risk assessment of individual hazard groups; (vi) The developed framework is applied to real case studies from the Nuclear Power Plants (NPP) industry
Drouet, Jessica Boog Georges. « Facteurs de risque de césarienne sur le deuxième jumeau ». [S.l.] : [s.n.], 2007. http://castore.univ-nantes.fr/castore/GetOAIRef?idDoc=20716.
Texte intégralBou, Nader Raymond. « Modélisation du management des risques industriels et de la responsabilité sociale des entreprises : Cas des entreprises libanaises ». Electronic Thesis or Diss., Toulon, 2017. http://www.theses.fr/2017TOUL2001.
Texte intégralThe aim of our thesis is to study the current practice of CSR in the context of the Lebanese industrial companies and to examine the relationship between CSR practices and risk management, using statistical techniques as inferential tests, factor analysis and multiple linear regression models. It is in the latter that the main contribution of this research has been made. This research has made it possible to perceive CSR as more than just a marketing and public relations tool but also a real tool influencing risk in companies. Our research broadens the knowledge base in this field in the Lebanese context, focusing on the management and practices of the company in terms of risk management, in order to better manage the social, environmental, and community based activities by CSR. The results of this study will enable researchers to create a stronger theoretical and empirical basis on which future research on the subject of CSR and risk management through CSR can be developed
Sadefo, Kamdem Jules. « Méthodes analytiques pour le risque des portefeuilles financiers ». Reims, 2004. http://www.theses.fr/2004REIMS023.
Texte intégralIn this PhD thesis, we are concerned by the analytically and numerically estimation for Value-at-Risk and Expected Shortfall for linear or quadratic portfolios with the mixture of elliptically distributed risk factors. As illustration, we provide some explicit estimation of the Value-at-Risk and Expected Shortfall, when the risk factors change with mixture of generalized Laplace distribution or the mixture of t-distributions. Also, some numerical tests have been done, by using dta from CAC 40 french market
Bou, Nader Raymond. « Modélisation du management des risques industriels et de la responsabilité sociale des entreprises : Cas des entreprises libanaises ». Thesis, Toulon, 2017. http://www.theses.fr/2017TOUL2001/document.
Texte intégralThe aim of our thesis is to study the current practice of CSR in the context of the Lebanese industrial companies and to examine the relationship between CSR practices and risk management, using statistical techniques as inferential tests, factor analysis and multiple linear regression models. It is in the latter that the main contribution of this research has been made. This research has made it possible to perceive CSR as more than just a marketing and public relations tool but also a real tool influencing risk in companies. Our research broadens the knowledge base in this field in the Lebanese context, focusing on the management and practices of the company in terms of risk management, in order to better manage the social, environmental, and community based activities by CSR. The results of this study will enable researchers to create a stronger theoretical and empirical basis on which future research on the subject of CSR and risk management through CSR can be developed
Masoud, Khaldoun. « Développement d'une approche multiplexe pour l'évaluation du risque d'intoxination staphylococcique ». Strasbourg, 2010. http://www.theses.fr/2010STRA6149.
Texte intégralThe potential hazard of staphylococci to the public health is mainly characterized by staphylococcal food poisoning (SFP) and staphylococcal toxic shock. They result from a mitogenic activation of lymphocytes T leading to a massive pro-inflammatory cytokines release, an immune response triggered by recognizing the superantigenic staphylococcal enterotoxins (SEs). Diseases severity depends on the toxin; its serotype, the dose administrated, its affinity to T cells receptors (TCR), etc…, and also depending on the age of the patient, its immune state, the clonotype of the TCR, etc…According to the new European Criteria (EC 1441/2007 of 5 December 2007), staphylococcal risk assessment requires a reference method for the detection of SEs. Such a method should be time and cost effective, and also applicable for analysis of proteinous matrices such as dairy products, meat, human biologic fluids, supernatant of SE positive staphylococci, etc…My work introduces a microsphere (Luminex®) -based multiplex suspension immunoassay with the possibility to analyze quantitatively and qualitatively eight serotypes of SEs, which two are the most-cited over food poisoning epidemics in France and in the world (SEA and SED), another is referred as a potential biological weapon (SEB) and others may be implicated in non-menstrual toxic shock (SEA-E, H, and I). Different genes expressing the eight enterotoxins are cloned into expression plasmids and the recombinant proteins are purified and identified. Maximal conditions of purification were taken on for preparation anatoxins from stable and highly purified enterotoxins, for rabbit's immunization. Polyclonal antibodies for each of the enterotoxins are treated separately, purified and only the specific ones are recovered for specific immune detection. Antigenic characteristics of enterotoxins in the presence of their own antibodies were evaluated by Dot-blot. Thereafter, eight sandwich immunoasays were developed (with optimized concentrations) and standard curves were plotted. A model of regression analysis of five parameters was adopted for best curve fitting with 95% degree of confidence for all the parameters. A confidence interval (CI) obtained was between 0. 002 and 0. 005 with a high determination level; R2 = 0. 98. The overall limit of detection was less than 30 pg/ml with a coefficient of variation between 4 and 33%. Our participation in a research program of the Agence Nationale de la Recherche (ANR) named SEFRO allowed us to use this new method of SEs detection for food safety improvement concerning SEs expression within the different steps of cheese manufacture and for different types of French cheese. Additionally, we evaluated the test for the analysis of enterotoxins expression in staphylococcal supernatants during the different phases of bacterial growth. By profiting from the picomolar sensitivity of our test, there is no longer need to a prior concentration of enterotoxins before dairy samples analysis (referring to the dialysis in the official method agreed by the AFSSA), with limits of detection between 100 and 200 pg per gram of cheese. Its application might be enlarged to other nutrient products. Epidemiologic approaches and the results of bacterial analysis support the possibility to use this test as a phenotyping tool for the investigation of Staphylococcus aureus strains isolated from patients or from healthy persons. In the absence of a reference method for SEs measurement, our test might be an alternative choice for specific, quantitative, sensible and rapid assessment of a potential biological threat and for food hazard control concerning the staphylococcal danger
Guseva, Canu Irina. « Etude épidémiologique des travailleurs exposés au risque d'incorporation d'uranium ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00812524.
Texte intégralRaboun, Oussama. « Multiple Criteria Spatial Risk Rating ». Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLED066.
Texte intégralThe thesis is motivated by an interesting case study related to environmental risk assessment. The case study problem consists on assessing the impact of a nuclear accident taking place in the marine environment. This problem is characterized by spatial characteristics, different assets characterizing the spatial area, incomplete knowledge about the possible stakeholders, and a high number of possible accident scenarios. A first solution of the case study problem was proposed where different decision analysis techniques were used such as lotteries comparison, and MCDA (Multiple Criteria Decision Analysis) tools. A new MCDA rating method, named Dynamic-R, was born from this thesis, aiming at providing a complete and convincing rating. The developed method provided interesting results to the case study, and very interesting theoretical properties that will be presented in chapters 6 and 7 of this manuscript
Van, Meenen Jean-Marc. « La violence paroxystique en milieu scolaire : approche cindynique et opérationnelle d'anticipation du risque ». Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0026/document.
Texte intégralThis doctoral thesis proposes a rational and scientific approach to the phenomenon of paroxysmal violence in schools. Through the prism of urban “cindynics” (risk science), we first highlight the possible motivations of violent reaction against the school system and its actors. Are they sufficient to explain the use of extreme violence ? We secondly offer some consolidated elements to answer, based on 156 events spread over a century across 5 continents and 25 countries. After extensive focus on spaces of commission, a typology of the perpetrators is precisely established. The analysis then focuses on socio-cultural determinants of these criminal actions in a single, cyclical and societal combination.This detailed review then allows the modeling of criminal processes at work, gender and age of the perpetrators. Criticality levels of identified risk factors are estimated to bring out the “minimum cuts” of a causal tree (pre-accident phase). It aggregates to a tree consequences (post-accident phase) around the “central event dreaded” that is the act of school shooting. The interest of the “bow tie” thus formed extends beyond the stage of diagnosis. This discursive model assumes ultimately declination barriers of risk mitigation that prefigure, in a transactional approach to security, a comprehensive and multidisciplinary strategy of anticipation to mass murders in French and European schools or universities
Poba-Nzaou, Placide. « Processus d'adoption et réduction du risque d'implantation des PGI dans les PME : une étude de cas multiples ». Thèse, Université du Québec à Trois-Rivières, 2008. http://depot-e.uqtr.ca/1877/1/030105355.pdf.
Texte intégralRODE, GUICHARD SYLVIE. « Neoplasie endocrinienne multiple de type 1 : etude clinique, biologique et genetique d'une famille ; identification des sujets sains et des sujets a risque ». Lyon 1, 1994. http://www.theses.fr/1994LYO1M016.
Texte intégralCohen, Carole. « Considérations bioéthiques sur les grossesses multiples : la réduction embryonnaire ». Paris 5, 1996. http://www.theses.fr/1996PA05P078.
Texte intégralFaverjon, Céline. « Risk based surveillance for vector-borne diseases in horses : combining multiple sources of evidence to improve decision making ». Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22604/document.
Texte intégralEmerging vector-borne diseases are a growing concern, especially for horse populations, which are at particular risk for disease spread. In general, horses travel widely and frequently and, despite the health and economic impacts of equine diseases, effective health regulations and biosecurity systems to ensure safe equine movements are not always in place. The present work proposes to improve the surveillance of vector-borne diseases in horses through the use of different approaches that assess the probability of occurrence of a newly introduced epidemic. First, we developed a spatiotemporal quantitative model which combined various probabilities in order to estimate the risk of introduction of African horse sickness and equine encephalosis. Such combinations of risk provided more a detailed picture of the true risk posed by these pathogens. Second, we assessed syndromic surveillance systems using two approaches: a classical approach with the alarm threshold based on the standard error of prediction, and a Bayesian approach based on a likelihood ratio. We focused particularly on the early detection of West Nile virus using reports of nervous symptoms in horses. Both approaches provided interesting results but Bayes’ rule was especially useful as it provided a quantitative output and was able to combine different epidemiological information. Finally, a Bayesian approach was also used to quantitatively combine various sources of risk estimation in a multivariate syndromic surveillance system, as well as a combination of quantitative risk assessment with syndromic surveillance (applied to West Nile virus and equine encephalosis, respectively). Combining evidence provided promising results. This work, based on risk estimations, strengthens the surveillance of VBDs in horses and can support public health decision making. It also, however, highlights the need to improve data collection and data sharing, to implement full performance assessments of complex surveillance systems, and to use effective communication and training to promote the adoption of these approaches
Subbotin, Alexander. « Horizons d'investissement multiples et dynamique des prix des titres ». Phd thesis, Université Panthéon-Sorbonne - Paris I, 2010. http://tel.archives-ouvertes.fr/tel-00510035.
Texte intégralMouchet, Le Moal Julie. « Vaccination et risque de démyélinisation : existe-t-il un lien ? Exemples des vaccins anti-hépatite B et anti-papillomavirus ». Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0015/document.
Texte intégralWhile vaccines represent a great achievement for public health, the risk of adverse effects is a real threat for vaccine acceptability by both the population and healthcare professionals. France still ranks as the country having the highest vaccine defiance. This often turned into poor vaccination coverages. This origin of this mistrust in vaccines is probably related to the intense polemic around anti-hepatitis B (HB) vaccination and the risk of multiple sclerosis in the 1990’s. The main aim of this thesis was to assess the putative link between vaccination and demyelinating disorders by considering two examples: anti-HB and anti-papillomavirus (HPV) vaccines. For both vaccines, methods adopted a stepwise evidence-based approach. Hypothesis generation was based on evidence regarding the biological plausibility, the published case reports, the disproportionality analyses conducted in the US Vaccine Adverse Event Reporting System (VAERS) and the analysis of signals detected by spontaneous reporting systems, if any. For the research question centered on the anti-HB vaccination, observed-to-expected analyses based on all confirmed cases reported to the French pharmacovigilance in the 1990’s were also conducted. Systematic reviews of all individual studies having assessed the possible association between demyelination and either anti-HB or HPV vaccines were then conducted while meta-analyses brought pooled risk estimates of all evidence published so far. Results were non-conclusive for both vaccines. For anti-HB vaccination, several elements could give credence to an association with central demyelination: a weak and indirect biological plausibility, the analysis of the French signal detected in the 1990’s which revealed a complete disjunction between the target and the joint populations, and the results of the disproportionality analyses in VAERS. Nevertheless, neither the meta-analysis nor the observed-to-expected analyses (although might be easily reversed by a moderate degree of underreporting), provided statistically significant findings. If the excess risk actually existed, it would be weak and would be a concern for adults only. The current recommendations which are minimizing the probability of the French population to be exposed at an adult age, are therefore more than justified. For the anti-HPV vaccination, after reviewing all materials available, the risk of central demyelination seems, at this date, unlikely. Nevertheless, a doubt remains regarding a possible excess risk of Guillain Barré Syndrome (GBS) in the follow of an anti-HPV immunization. More specific studies would be needed, although the rarity of this event renders its evaluation difficult. From the studies already conducted, it was estimated that this excess risk, if any, would be lower than 1 per 1,000,000 doses sold. To conclude, a strong association with a risk of central demyelination can be ruled out for both vaccines, making the benefit and risk balances still largely positive for both products if used in their current target populations. In that context, an independent, clear and scientifically-based communication is the key element to promote vaccination programmes and to generate the confidence and adherence of the general population. Political decisions also carry a heavy responsibility in ensuring trust towards vaccination programmes, as the suspension of national immunization campaigns which could have long-lasting deleterious consequences. The future of vaccine pharmacovigilance could rely on the implementation of a collaborative GP-patient network-based solution using SMS and smartphones, as already experimented in Australia. While collecting potential adverse effects of vaccines, it would also be a unique opportunity to place the patients at the heart of the surveillance system, giving them a voice and potentially contributing to restore their confidence in vaccines and even, in the decision-makers in the field of public health
Rouatbi, Wael. « Essays on the governance role of multiple large shareholders ». Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC0104.
Texte intégralThe present dissertation is a collection of three essays. The first one investigates the role of multiple large shareholders (MLS) in corporate risk-taking. Using a sample of publicly listed French family firms over the period 2003‒2012, we show that the presence, number and voting power of MLS, beyond the controlling owner, are associated with higher risk-taking. Our results suggest that MLS help restrain the propensity of family owners to undertake low-risk investments. This effect is much stronger in firms that are more susceptible to agency conflicts. The results highlight the important governance role played by MLS in family firms and may explain why MLS are associated with higher firm performance.The second essay studies the relation between MLS, beyond the controlling owner, and corporate debt maturity. We employ a large data set of French publicly traded firms during the period 1998–2013 and we find strong evidence that firms with MLS exhibit shorter debt maturity. This result indicates that MLS curb the extraction of private benefits by the controlling owner and reduce her preference for less monitoring through the use of longer maturity debt. The findings are robust to a number of checks, including addressing endogeneity concerns and using alternative sample compositions and alternative regression frameworks.The third essay examines the effect of MLS on the choice of debt source. Using a sample of 6,238 firm–year observations covering 654 French listed firms from 1998 to 2013, we show that reliance on bank debt financing increases with the presence of MLS and with their contestability of the controlling owner’s power. Moreover, we find that the effect of MLS on debt choice is more pronounced when agency problems between controlling and minority shareholders are more severe. Taken together, our results suggest that the presence of MLS reduces the incentive of the controlling owner to avoid scrutiny and to insulate herself from bank monitoring, leading to more reliance on bank debt
Cholley, Pascal. « Analyse génétique des souches multi-résistantes de Pseudomonas aeruginosa dans l'Est de la France : apport prédictif sur le risque infectieux ». Besançon, 2010. http://www.theses.fr/2010BESA0012.
Texte intégralPseudomonas aeruginosa has become an important hospital pathogen because of the number and severity of infections. The objective of this thesis was to describe the hospital epidemiology of P. Aeruginosa, including that of multi-resistant strains by using various tools of molecular biology. The first part of this thesis is devoted to an overview of the literature, the second part describes the different techniques used and the third part has different work. Genotyping by PFGE allowed us to evaluate the role of the inert environment in the epidemiology of P. Aeruginosa in adult intensive care units. This technique has also highlighted the role of cross-transmission as a vehicle for dissemination of strains of P. Aeruginosa multi-resistant to antibiotics. The MultiLocus Sequence Typing of a wide range of multi-resistant strains isolated throughout the inter-region has provided important information : there are international epidemic clones that have the capacity to accumulate resistance mechanisms and spread in hospitals. The hypothesis of a panmictic population for this bacterium is being challenged for the sub-population " multidrug-resistant P. Aeruginosa hospital ". Molecular epidemiology is essential to characterize these strains and to define control strategies. Our work suggests that these control strategies should involve at least a policy fo antibiotic use, prevention of cross-transmission involving screening and hygiene measures. Control of multi-resistant bacteria represents a challenge of today and tomorrow for the different health actors
Morisot, Adeline. « Méthodes d’analyse de survie, valeurs manquantes et fractions attribuables temps dépendantes : application aux décès par cancer de la prostate ». Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTT010/document.
Texte intégralThe term survival analysis refers to methods used for modeling the time of occurrence of one or more events taking censoring into account. The event of interest may be either the onset or the recurrence of a disease, or death. The causes of death may have missing values, a status that may be modeled by imputation methods. In the first section of this thesis we made a review of the methods used to deal with these missing data. Then, we detailed the procedures that enable multiple imputation of causes of death. We have developed these methods in a subset of the ERSPC (European Randomized Study of Screening for Prostate Cancer), which studied screening and mortality for prostate cancer. We proposed a theoretical formulation of Rubin rules after a complementary log-log transformation to combine estimates of survival. In addition, we provided the related R code. In a second section, we presented the survival analysis methods, by proposing a unified writing based on the definitions of crude and net survival, while considering either all-cause or specific cause of death. This involves consideration of censoring which can then be informative. We considered the so-called traditional methods (Kaplan-Meier, Nelson-Aalen, Cox and parametric) methods of competing risks (considering a multistate model or a latent failure time model), methods called specific that are corrected using IPCW (Inverse Ponderation Censoring Weighting) and relative survival methods. The classical methods are based on a non-informative censoring assumption. When we are interested in deaths from all causes, this assumption is often valid. However, for a particular cause of death, other causes of death are considered as a censoring. In this case, censoring by other causes of death is generally considered informative. We introduced an approach based on the IPCW method to correct this informative censoring, and we provided an R function to apply this approach directly. All methods presented in this chapter were applied to datasets completed by multiple imputation. Finally, in a last part we sought to determine the percentage of deaths explained by one or more variables using attributable fractions. We presented the theoretical formulations of attributable fractions, time-independent and time-dependent that are expressed as survival. We illustrated these concepts using all the survival methods presented in section 2, and compared the results. Estimates obtained with the different methods were very similar
Padié, Sophie. « Réponse des cervidés à la chasse : stratégies d’utilisation de l’espace à multiples échelles et conséquences sur la végétation ». Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20185.
Texte intégralHunting – similarly to natural predation – induces behavioural responses of hunted individuals which aims at avoiding or reducing risk. Particularly, changes in space use are frequently observed, but the articulation and determinants of these changes at multiple spatial scales are still poorly understood. Also, although it has been suggested that these changes might cascade on the vegetation, this remains to be tested. To fill these gaps, I (1) studied a hunted roe deer population living in an agricultural landscape in southern France where roe deer can find open risky habitats and woody covers; and (2) tested black-tailed deer behavioural response to an experimental hunt in a predator- and hunting-free population in the Haïda-Gwaii archipelago (BC, Canada). I also investigated the possible cascading effects on the vegetation. I showed that roe deer responded to increased hunting pressure at multiple scales, reducing their use of the risky habitats and, in specific situations, their distance to the nearest cover. At day-time those two responses were coupled at the individual level. Generally, landscape openness constrained individual responses and strategies. In the hunting-for-fear experiment conducted on Haida Gwaii, I found that only the deer less-tolerant to human disturbance avoided the hunting area. A simultaneous reduction in browsing pressure on two out of the four plant species monitored was found however. I integrated these results in a general discussion on the possible role of hunting as a tool to manage abundant deer populations and their impacts on the vegetation
Abdallah, Mouhammed. « Vulnérabilité des ouvrages en maçonnerie à des mouvements de terrain : méthodologie d'analyse par méthodes statistiques et par plans d'expériences numériques sur les données de la ville de Joeuf ». Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL019N/document.
Texte intégralThe context of our study concerns ground movements that may occur in Lorraine as a result of mining subsidence events and their impact on traditional masonry houses. When such an event occurs, houses suffer disorders resulting from efforts in the structure caused by the movement of the ground. The response that characterizes the state of the structure depends on the geometrical, physical and mechanical characteristics. However, the discontinuous nature of the masonry and the interactions complexity between masonry blocks makes it difficult to determine that response. The same is true about the soil-structure interaction. The purpose of this research is to study, by numerical modelling with the distinct element method, experimental design planning and response surfaces, the behaviour of masonry structures subjected to a typical mining subsidence event and to define from this study some criteria making possible the estimation of the vulnerability of all the buildings of a city. A first simplified analysis describes the principle of the used methodology which is then applied to the study of all houses of the city of Joeuf, used as a pilot site. This methodology is based on an analysis of the total length of the opened joints, which are considered as similar to cracks in the structure. Then, a typology analysis helps first to distinguish 4 groups (types) of houses which have similar characteristics. On each of these groups, the methodology is applied consistently, based on the geometrical characteristics of the houses facades and then leads to the formulation of vulnerability functions that use the technique of orthogonal regression
Marti, soler Helena. « Modélisation des données d'enquêtes cas-cohorte par imputation multiple : Application en épidémiologie cardio-vasculaire ». Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00779739.
Texte intégralScavo, Linda. « Effet de la mélatonine sur le risque d’ostéoporose, le métabolisme énergétique cérébrale et la remyélinisation dans un modèle expérimental de souris EAE Melatonin Therapy Modulates Cerebral Metabolism and Enhances Remyelination by Increasing PDK4 in a Mouse Model of Multiple Sclerosis ». Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS108.
Texte intégralMultiple Sclerosis (MS) is a chronic auto-immune demyelinating and neurodegenerative disease of the CNS. It represents the leading cause of non-traumatic disability in young adults and especially women. Despite all the efforts of researchers, the exact cause of MS remains unknown to this day. According to them, MS is considered a disease that occurs in the presence of environmental factors combined with genetic factors. Current therapy uses drugs that suppress immunological attacks without suppressing the entire immune system. Melatonin has been shown to be a potent neuroprotective candidate to reduce the loss of myelin.The aim of this work is to examine the clinical correlation between serum melatonin and proCT in MS patients and to assess the effect of melatonin on osteoporosis, metabolic pathways and remyelination in the brain. in vivo. To do this, different molecular and cellular biology techniques were used in the experimental model of autoimmune encephalomyelitis (EAE).The results obtained are divided into three parts. In the first part, the data showed a significant increase in serum proCT levels in MS patients, inversely correlated with melatonin and osteocalcin OCN levels compared to healthy subjects. In the second part, we demonstrated that melatonin decreased the average clinical scores, significantly reduced serum proCT levels and increased the level of 25-hydroxyvitamin D, calcium and OCN in EAE mice compared to control EAE mice. In the third part, the results showed that melatonin increased the level of anti-inflammatory cytokines (interleukin-10 (IL-10) and interleukin-4 (IL-4)) and decreased the rate of pro-inflammatory cytokines (tumor necrosis factor – alpha (TNF-α) and interleukin 1-beta (IL-1β)) in EAE mice compared to control EAE mice. We also demonstrated that the level of myelin oligodendrocyte glycoprotein (MOG), the level of myelin basic protein (MBP) and the level of myelin oligodendrocytic basic protein (MOBP) wereincreased by it. In addition, it has led to a significant increase in brain concentrations of acetate, N-acetylaspartate (NAA) and 3-hydroxy-3-methylglutaryl-Coenzyme-A reductase (HMGCR). Expression levels of mRNA and pyruvate dehydrogenase kinase-4 (PDK-4) proteins also increased in melatonin-treated mice compared to untreated EAE mice. Treatment with melatonin resulted in increased lactate levels in the brain, while the activity of the active and total pyruvate dehydrogenase (PDC) complex, an enzyme under the control of PDK-4, was suppressed.In conclusion, this study suggests that ProCT may be a biomarker in patients with MS. The results obtained on melatonin-treated EAE mice demonstrate its importance in reducing the severity of the disease and intracerebral inflammation, as well as improving bone metabolism, which consequently reduces osteoporosis. Likewise, this treatment is important for the reduction of inflammatory mediators while stimulating oligodendrogenesis. Thus, melatonin exerts a modulatory effect on the metabolic pathways involved in brain metabolism and improves mitochondrial dysfunction
Dieudonne, Maël. « Une société pathogène ? : les hypersensibilités environnementales au prisme de la sociologie cognitive ». Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE2134/document.
Texte intégralFor about two decades, the number of people claiming to suffer from multiple chemical sensitivity or electromagnetic hypersensitivity has been steadily increasing in France.T hese persons experience various and sometimes quite disabling somatic symptoms, which they attribute to exposure either to chemicals or to anthropogenic electromagnetic fields. The definition, and even the existence of these diseases are controversial. They are not legally recognized and their victims resort to self-diagnosis. However, this is not a cognitively easy task. Its implications are also far-reaching: it results in a radical change in their views of themselves, their environment and their community, as well as significant alterations in their daily lives and behaviour. It is thus an interesting phenomenon to explain for a cognitive sociology concerned with how mental representations evolve and influence conduct. Such is the purpose of this thesis. The analysis relies mostly on ethnographic materials and is conducted in a comprehensive and ecological perspective. It falls into three stages. The first one is devoted to an exploration of the controversies aroused by environmental sensitivities, so as to clarify their lack of legitimacy. The second one deals with the subjective experience and biographical trajectories of environmentally sensitive persons. The last one tries to explain the appearance and persistence of their conviction that they are hypersensitive with a utilitarian model in which emotions play a prominent role. To conclude, a comparison is outlined with other epidemics of medically unexplained symptoms
Nguyen, Thi hai yen. « Multiple exposures and co-exposures to chemical neurotoxic agents and intense physical constraints among male blue-collar workers in the agriculture, manufacturing, and construction sectors in France Multiple Exposures and Co-exposures to Occupational Hazards among Agricultural Workers : A Systematic Review of Observational Studies ». Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0065.
Texte intégralA wide range of studies has demonstrated the relationships between diverse types of occupational exposures,taken independently, and adverse health outcomes. Yet, the prevalence and impact of multiple occupational exposures or co-exposures have rarely been explored despite the ubiquity of numerous hazards. Therefore, multiple occupational exposures/co-exposures and their impact on health are considered as a major challenge of epidemiologic research inthe occupational health and safety area. A systematic review concerning the agriculture sector was carried out based on the titles, abstracts and fulltexts screening of 36,404 initial articles from 5 well-known databases and 2 North American complementary sources. The findings from the 15 papers finally included suggested that multiple chemical exposures were significantly associated with an increased risk of respiratory diseases, cancers, DNA and cytogenetic damages. Multiple physical exposures were shown to increase the risk of hearing loss while co-exposures to physical and biomechanical hazardswere associated with an increased risk of musculoskeletal disorders. However, no studies included in the systematic review explored either occupational co-exposures to both physical and chemical factors or occupational co-exposures to biomechanical and chemical factors.The results described in the systematic review raised the necessity to conduct further studies multipleoccupational exposures and co-exposures among workers. Therefore, multiple occupational exposures and coexposures’ prevalences to chemical neurotoxic agents (CNAs) and intense physical constraints (IPCs) were examined among 5,587 French male blue-collar workers (BCWs) in the agriculture, manufacturing, and construction sectors based on the cross-sectional and national SUMER 2010 survey. About 6% of male BCWs were co-exposed to IPCs andCNAs in these three sectors (p=0.29). Multiple exposures to IPCs was predominantly observed (35%, p <0.001), while multiple exposures to CNAs was much lower (2%, p <0.001) among male BCWs in three sectors.The findings highlight the necessity to carry out further studies on multiple occupational exposures/coexposures to diverse hazards and their impact on workers’ health. These further researches are required to improve occupational safety and the efficiency of health care surveillance and occupational disease prevention
Becam, Adrien. « Mesure de performance et liquidité dans l'industrie des hedge funds ». Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLED074.
Texte intégralThe hedge fund industry experienced a fast growth of its assets under management. However, its poor performance during the 2008 financial crisis and the recent years questioned the absolute character of hedge fund returns.My thesis work aims to explicit the sources of the measured performance of hedge funds.The first chapter demonstrates a positive link between the magnitude of serial correlation in hedge funds returns and their outperformance. In accordance with the hypothesis of a bias in the estimates, the most serially correlated funds also have the lowest measured risk exposures.The second chapter shows that serial correlation in hedge fund returns comes only really partially from liquidity issues, and so returns smoothing by fund managers is pervasive.Finally, the third chapter highlights that the risk on the capital of financial intermediaries is a new risk factor strongly explaining the cross-section of hedge fund returns. A portion of the alpha comes in fact from a risk premia for bearing an exposure to this factor
Moreno, Betancur Margarita. « Regression modeling with missing outcomes : competing risks and longitudinal data ». Thesis, Paris 11, 2013. http://www.theses.fr/2013PA11T076/document.
Texte intégralMissing data are a common occurrence in medical studies. In regression modeling, missing outcomes limit our capability to draw inferences about the covariate effects of medical interest, which are those describing the distribution of the entire set of planned outcomes. In addition to losing precision, the validity of any method used to draw inferences from the observed data will require that some assumption about the mechanism leading to missing outcomes holds. Rubin (1976, Biometrika, 63:581-592) called the missingness mechanism MAR (for “missing at random”) if the probability of an outcome being missing does not depend on missing outcomes when conditioning on the observed data, and MNAR (for “missing not at random”) otherwise. This distinction has important implications regarding the modeling requirements to draw valid inferences from the available data, but generally it is not possible to assess from these data whether the missingness mechanism is MAR or MNAR. Hence, sensitivity analyses should be routinely performed to assess the robustness of inferences to assumptions about the missingness mechanism. In the field of incomplete multivariate data, in which the outcomes are gathered in a vector for which some components may be missing, MAR methods are widely available and increasingly used, and several MNAR modeling strategies have also been proposed. On the other hand, although some sensitivity analysis methodology has been developed, this is still an active area of research. The first aim of this dissertation was to develop a sensitivity analysis approach for continuous longitudinal data with drop-outs, that is, continuous outcomes that are ordered in time and completely observed for each individual up to a certain time-point, at which the individual drops-out so that all the subsequent outcomes are missing. The proposed approach consists in assessing the inferences obtained across a family of MNAR pattern-mixture models indexed by a so-called sensitivity parameter that quantifies the departure from MAR. The approach was prompted by a randomized clinical trial investigating the benefits of a treatment for sleep-maintenance insomnia, from which 22% of the individuals had dropped-out before the study end. The second aim was to build on the existing theory for incomplete multivariate data to develop methods for competing risks data with missing causes of failure. The competing risks model is an extension of the standard survival analysis model in which failures from different causes are distinguished. Strategies for modeling competing risks functionals, such as the cause-specific hazards (CSH) and the cumulative incidence function (CIF), generally assume that the cause of failure is known for all patients, but this is not always the case. Some methods for regression with missing causes under the MAR assumption have already been proposed, especially for semi-parametric modeling of the CSH. But other useful models have received little attention, and MNAR modeling and sensitivity analysis approaches have never been considered in this setting. We propose a general framework for semi-parametric regression modeling of the CIF under MAR using inverse probability weighting and multiple imputation ideas. Also under MAR, we propose a direct likelihood approach for parametric regression modeling of the CSH and the CIF. Furthermore, we consider MNAR pattern-mixture models in the context of sensitivity analyses. In the competing risks literature, a starting point for methodological developments for handling missing causes was a stage II breast cancer randomized clinical trial in which 23% of the deceased women had missing cause of death. We use these data to illustrate the practical value of the proposed approaches
Graff, Kevin. « Contribution à la cartographie multirisques de territoires côtiers : approche quantitative des conséquences potentielles et des concomitances hydrologiques (Normandie, France) Analysis and quantification of potential consequences in multirisk coastal context at different spatial scales (Normandy, France) Characterization of elements at risk in the multirisk coastal context and at different spatial scales : Multi-database integration (normandy, France) ». Thesis, Normandie, 2020. http://www.theses.fr/2020NORMC001.
Texte intégralThe coastal environment in Normandy is conducive to a convergence of multiple hazards (erosion, marine submersion, flooding by overflowing streams or upwelling of a water table, turbid flooding by runoff, coastal or continental slope movement). Because of their interface positions, important regressive dynamics go between the marine and continental processes. This interaction will occur within the slopes and valleys where coastal populations and their activities have tended to become more densified since the 19th century. In this context, it is necessary to adopt a multi-hazard and multi-risk approach considering the spatial or temporal confluence of several hazards and their possible cascading effects and to assess the multi-sector impacts generated. by these vagaries.As part of this thesis, as well as in the ANR RICOCHET program, three study sites were selected at the outlet of the coastal rivers: from Auberville to Pennedepie, from Quiberville to Dieppe and from Criel-sur-Mer to Ault due to significant issues and strong interactions between hydrological and gravitational phenomena. Two main objectives have been carried out: (1) an methodological development on analyses of potential consequences by considering all the elements at risk within a study territory through a multiscaling approach; (2) an analysis of hydrological concomitances through a both statistical and spatial approach
Suescun, Juliana Ruiz. « Courbes de fragilité pour les ponts au Québec tenant compte du sol de fondation ». Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/1576.
Texte intégralCohen, Laurence. « Le co-investissement par des Business Angels et des Capital-investisseurs dans les jeunes entreprises technologiques et trajectoires de croissance : approche en termes de gouvernance d'entreprise et études de cas comparatives ». Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE3073.
Texte intégralIn their seed, young technological ventures seeking resources to finance their development may seek business angels (BAs) and venture capitalists (VCs). Our research shall include the type of investment (only BAs, BAs and VCs in sequential or simultaneous co-investment) implemented and this leads to the question of the nature and the quality of the relations and interactions among various categories of investors and the entrepreneur, in the sense that these investors may influence the dynamic of growth, and be themselves influenced by that dynamic. It implies that the pace and intensity of the venture growth of the young technological ventures do not have any kind of determinism, but they develop rather in a dynamic manner within the field of the interaction between the main providers of resources. We jointly mobilize agency theory and cognitive and effectual approaches in order to analyse the co-investment of BAs and VCs. We conducted a multiple-case study with a comparative aim concerning three young companies of the Rhône-Alpes Region. We have shown that, when the cognitive schemes of the BAs and / or the entrepreneur are close to that of the VC, the relations and interrelations can occur to a lesser cognitive cost during the pre-investment phase and that the sequential or simultaneous co-investment may take place. Our results indicate that a funding by BAs is associated with a slower venture growth and that a sequential co-investment allows the stabilisation of the venture growth without a very high growth for the company. We are also highlighting that when the BAs and / or the VCs recognize the high growth potential of the young company very early in the investment process the VCs really need to integrate the BAs who have a specific experience, like their entrepreneurial past and their knowledge of the sector. The predictive approach of these three stakeholders: entrepreneur, VCs and BAs promotes the implementation of a simultaneous co-investment. In this context, the investors (BAs and VCs) can serve as active partners alongside the entrepreneur and help ensure that the young company follows a high venture growth, or even a hyper growth
Bahuaud, Mathilde. « Vaccination anti-pneumococcique chez les sujets à risque d'infections invasives à pneumocoques et prévention de l'hyporéponse Immunogenicity and persistence of the 13-valent pneumococcal conjugate vaccine (PCV13) in patients with untreated smoldering multiple myeloma (SMM) : a pilot study Immunogenicity and persistence of a prime-boost re-vaccination strategy for pneumococcal vaccines in patients with rheumatoid arthritis Pneumococcal vaccination in patients with systemic lupus erythematosus : a multicenter placebo-controlled randomized double-blind study Prevention of hyporesponsiveness by modulation of schedule and doses of pneumococcal vaccine immunization ». Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCB067.
Texte intégralTwo vaccines are currently available for the prevention of invasive pneumococcal diseases (IPD): a polysaccharide vaccine, Pneumovax® (PPV23) and a conjugate vaccine, Prevenar13® (PCV13), inducing protection against 23 and 13 serotypes, respectively. PPV23 is considered to be weakly immunogenic, particularly in the elderly and immunocompromised patients. PCV13, however, due to the conjugation to a carrier protein, has the advantage of inducing a T-dependent immune response, not observed with PPV23 vaccine. In our work, we therefore evaluated the impact of vaccine strategies using PCV13 and PPV23 on different populations of patients at risk of IPD. In a first study, our results on anti-pneumococcal vaccination in patients with smoldering myeloma (SMM) showed that a single dose of PCV13 induces a transient immune response and long term persistence. These results suggested the use of a vaccination schedule including several doses of PCV13 or association with the PPV23. Since 2013, this combined strategy of PCV13 and PPV23 is recommended by la Haute Autorité de Santé (HAS) for patients at risk, with the following delays: a dose of PCV13 followed by a dose of PPV23, 8 weeks later. We then studied this combined vaccine strategy in patients at risk of IPD: patients with systemic lupus erythematosus (SLE) and patients with rheumatoid arthritis (RA). Our results show a short-term immunogenicity of the combined strategy, but a protection that does not persist beyond two years. Surprisingly, antibody levels 2 years after vaccination are lower than pre-vaccine levels for RA patients. This negative effect of PPV23 on PCV13-induced immune response is called hyporesponsiveness. This phenomenon, observed in RA patients, is not found in SLE patients who received PPV23 vaccination at distance from PCV13. These results suggest that the delayed vaccination schedule (ie, PPV23 vaccination six months after PCV13 instead of two months) could inhibit the hyporesponsiveness phenomenon. In a third study, we compared different vaccine strategies modulating vaccine doses and injection times in healthy volunteers but also in a mouse model of hyporesponsiveness developed in our laboratory. Our hypothesis was that modulation of the vaccine schedule using both vaccines could both induce long-term protection and prevent hyporesponsiveness. Our results showed that decreased doses of PPV23 or concomitant injection of both vaccines did not prevent hyporesponsiveness. However, by increasing the delay between PCV13 and PPV23, the phenomenon of hyporesponsiveness is limited. Clinical studies in patients at risk of IPD are needed to evaluate a delayed combined strategy, where PPV23 would be received at least 6 to 12 months after PCV13
Gauthier, François. « Analyse de descendances : une approche bio-informatique pour estimer le risque d'hypertension et d'obésité ». Thèse, 2007. http://hdl.handle.net/1866/7964.
Texte intégralKaveh, Nazanin. « Modélisation toxicocinétique d’un mélange de composés organiques volatils dans l’eau potable ». Thèse, 2012. http://hdl.handle.net/1866/9104.
Texte intégralRisk assessment focusing on exposure to mixtures by multiple routes can be improved with an understanding of the changes in internal doses due to interaction among chemicals. Physiologically based pharmacokinetic (PBPK) models are proven tools to predict the magnitude of interaction in various scenarios. In this study, four volatile organic compounds (VOCs) (toluene, nhexane, cyclohexane and isooctane) were chosen to represent petroleum products that could contaminate the drinking water (e.g. gasoline). PBPK models were used first to simulate exposure to a single chemical by a single route (inhalation, gavage) and simulate exposure to a mixture by multiple routes. PBPK models were validated by comparing simulations with in vivo data. These data were collected from groups of male Sprague-Dawley rats (n=5) exposed by inhalation (50 ppm of toluene, hexane; 300 ppm of cyclohexane and isooctane; 2-hr) or gavage (8.3, 5.5, 27.9, and 41.27 mg/kg, respectively, for toluene, hexane, cyclohexane and isooctane). For exposure to the mixture by multiple routes, same doses were used. The AUCs (mg/L x min) based on experimental data were 157.25, 18.77, 159.58 and 176.54 and the AUCs of the PBPKs model were 121.73, 21.91, 19.55 and 170.54, respectively, for toluene, hexane, cyclohexane and isooctane. Results from both PBPK models and in vivo data (single VOC, multiple routes vs. mixture, multiple routes) showed interactions between VOCs in the case of exposure to the mixture by multiple routes. This study demonstrated that the PBPK model is an effective tool to simulate exposure to mixtures of VOCs by multiple routes.
Allami, Youssef. « Profils de joueurs à problèmes : un test empirique du modèle des parcours multiples ». Thèse, 2017. http://hdl.handle.net/1866/21153.
Texte intégralAlamian, Arsham. « Individual and social determinants of multiple chronic disease behavioural risk factors in Canadian children and adolescents ». Thèse, 2010. http://hdl.handle.net/1866/4737.
Texte intégralBackground: Behavioural risk factors including physical inactivity, sedentary behaviour, cigarette smoking, alcohol drinking, and being overweight are major modifiable causes of chronic diseases such as cancer, cardiovascular diseases and diabetes. These lifestyle risk factors also co-occur in individuals and lead to increased risks of chronic diseases morbidity and mortality. Although single behavioural risk factors have been extensively studied, little is known about the distribution, clustering patterns and potential determinants of multiple behavioural risk factors for chronic diseases, particularly in children and adolescents. Objectives: This thesis aims 1) to describe the prevalence and clustering patterns of multiple chronic disease behavioural risk factors in Canadian children and adolescents; 2) to explore potential individual, social and school correlates of multiple chronic disease behavioural risk factors in Canadian children and adolescents; and 3) to assess, based on the conceptual framework of this study, the longitudinal influence of selected individual (sense of self, sense of achievement), social (social relations, others’ behaviours) and school (collective commitment to success, comprehension of rules) distal variables (variables situated at an intermediate distance from behaviours), as well as selected individual (demographics and personality traits), social (parental socioeconomic characteristics) and school (type of school, supportive environment, disciplinary climate) ultimate variables (variables situated at an utmost distance from behaviours) on the rate of occurrence of multiple chronic disease behavioural risk factors in Canadian children and adolescents. Methods: Cross-sectional data (n = 4724) from Cycle 4 (2000-2001) of the National Longitudinal Survey of Children and Youth (NLSCY) were used to describe the prevalence and clustering patterns of multiple behavioural risk factors in Canadian youth aged 10-17 years. Clustering was assessed using an observed to expected ratio method. Ordinal logistic regression was used to explore correlates of multiple behavioural risk factors in a cross-sectional sample (n = 1747) of Canadian youth aged 10-15 years from Cycle 4 (2000-2001) of the NLSCY. Prospective data (n = 1135) from Cycle 4 (2000-2001), Cycle 5 (2002-2003) and Cycle 6 (2004-2005) of the NLSCY were used to assess the longitudinal influence of selected distal and ultimate variables (as described above in the objectives) on the rate of occurrence of multiple behavioural risk factors in Canadian youth aged 10-15 years; this analysis was performed using longitudinal Poisson models. Results: Sixty-five percent of Canadian youth had two or more behavioural risk factors compared to only 10% with no risk factor. Behavioural risk factors clustered in multiple combinations. Specifically, the simultaneous occurrence of all five risk factors was 120% greater in males (observed/expected (O/E) ratio = 2.20, 95% confidence interval (CI): 1.31-3.09) and 94% greater in females (O/E ratio = 1.94, 95% CI: 1.24-2.64) than expected by chance. Older age (odds ratio (OR) = 1.95, 95% CI: 1.21-3.13), caregiver smoking (OR = 1.49, 95% CI: 1.09-2.03), reporting that most/all of one’s peers smoked (OR = 7.31, 95% CI: 4.00-13.35) or drank alcohol (OR = 3.77, 95% CI: 2.18-6.53), and living in a lone-parent family (OR = 1.94, 95% CI: 1.31-2.88) increased the likelihood of having multiple health risk behaviours. Youth with high self-esteem (OR = 0.92, 95% CI: 0.85-0.99) and youth from families with post-secondary education (OR = 0.58, 95% CI: 0.41-0.82) were less likely to have a higher number of behavioural risk factors. Finally, social distal variables (caregiver smoking, peer smoking, peer drinking) (Log-likelihood ratio (LLR) = 187.86, degrees of freedom = 8, P < 0.001) and individual distal variables (such as self-esteem) (LLR = 76.94, degrees of freedom = 4, P < 0.001) significantly influenced the rate of occurrence of multiple behavioural risk factors. Individual ultimate variables (age, sex, anxiety) and social ultimate variables (parental education, household income, family structure) exerted a less pronounced influence on the rate of co-occurrence of behavioural risk factors among youth. Conclusion: The results suggest that public health interventions should primarily target the individual distal (such as self-esteem) and social distal variables (such as parental smoking, peer smoking and peer drinking) to reduce or prevent the occurrence of multiple behavioural risk factors among youth. However, since distal variables (such as psychosocial characteristics and others’ behaviours) may be influenced by ultimate variables (such as demographic and socioeconomic characteristics), prevention programs and policies should also aim to improve the socioeconomic conditions of children and adolescents, particularly those of youth from less affluent families.
Taamouti, Abderrahim. « Problèmes d'économétrie en macroéconomie et en finance : mesures de causalité, asymétrie de la volatilité et risque financier ». Thèse, 2007. http://hdl.handle.net/1866/1507.
Texte intégralLeclerc, Bernard-Simon. « Facteurs de risque de chutes chez les aînés vivant dans la communauté et ayant recours aux services de soutien à domicile : covariables dépendantes du temps et événements récurrents ». Thèse, 2010. http://hdl.handle.net/1866/4286.
Texte intégralFalls in the elderly represent a major problem. It is therefore not surprising that the identification of factors that may increase the risk of falls has received much attention. Frailer seniors who need support to live in the community remained nonetheless poorly documented, although more recently, the Québec authorities have given high priority to interventions that target this population. Risk factors for falls are usually identified by observational prospective studies. Their optimal identification is however complicated by the fact that exposure may vary during the follow-up, and that an individual may experience more than one event. Twenty years ago, some researchers attempted to sensitize their peers in this respect, but their efforts were vain. Researchers continue today to neglect these considerations and to use improper statistical techniques, focusing on the proportion of fallers or the time to first fall. In doing so, we discard a significant amount of relevant information. In this thesis, we review the existing methods and propose a Cox hazards extension. We apply it in the study of potential fall-risk factors associated with 959 community-dwelling seniors using home-care services. Finally, we compare the results of the proposed Wei, Lin, & Weissfeld (WLW) method with those of several other techniques, notably the conventional logistic regression, the pooled logistic regression, the negative binomial regression and the Andersen & Gill regression. At baseline and every six months thereafter, participants were visited at home in order to ascertain information about potential risk factors. Falls were monitored by use of a calendar and monthly phone calls. Baseline exposure variables and updated time-varying exposures include socio-demographic characteristics, BMI, nutritional risk, gait and balance, alcohol consumption, home hazards, and medications. Almost all (99.6%) of participants showed at least one high risk factor. Exposure to multiple risks was frequent, with an average of 2.7 different high-risk factors per participant. The risk factors significantly associated to the risk of falling include male sex, age, history of falling, Berg balance score, BMI, use of benzodiazepines, number of home hazards and residential facility for seniors. Results demonstrate that the usual methods of analyzing risk factors for falling (any sort of fall as well as those leading to medical consultations) are inappropriate, as they produce considerable biases relative to the WLW model using time-dependent covariates. Bias for the considered effect measures comes from the manner in which the observed data (both measured exposures and health outcomes) was measured and defined as well as the way in which the statistical analysis took into account this information. An additional part of the thesis was undertaken to identify risk profiles of subjects regarding the recurrence of falling, defined as participants who reported at least two falls within six months of initial assessment at entry in the study. A classification and regression tree analysis classified the population into five groups differing in risk of recurrent falling, based on history of falls in the three months prior to the initial interview, Berg balance score, type of housing, and usual alcohol consumption in the six months preceding study entry. The relative risks varied from 0.7 to 5.1. A subsequent survival analysis showed that the length of time before becoming a recurrent faller varies among risk profiles. This thesis discusses highly topical subjects about a target population and a fall-risk screening activity which are priorities in the public health sector in Québec. We encourage researchers interested in the identification of risk of falls among the elderly to use the statistical method of Wei, Lin and Weissfeld because it takes into account updated time-varying exposures and multiple events. More research will be necessary to determine the best screening test for a given risk-factor in this setting and population.