Suchergebnisse

The analysis of the health risks associated with electromagnetic waves cannot be reduced solely to aspects of judicial expertise and compliance with regulatory exposure thresholds. It involves returning to the very foundations of the right of proof and articulating the length of time for the emergence of scientific knowledge and the time taken for the action to which the lawyer belongs. ; International audience ; The analysis of the health risks associated with electromagnetic waves cannot be reduced solely to aspects of judicial expertise and compliance with regulatory exposure thresholds. It involves returning to the very foundations of the right of proof and articulating the length of time for the emergence of scientific knowledge and the time taken for the action to which the lawyer belongs. ; L'analyse des risques sanitaires associés aux ondes électromagnétiques ne saurait être réduite aux seuls aspects de l'expertise judiciaire et du franchissement des seuils réglementaires d'exposition. Elle suppose de revenir aux fondements mêmes du droit de la preuve et d'articuler le temps long de l'émergence de la connaissance scientifique et le temps de l'action dans lequel s'inscrit le juriste.

In military environments, especially land field, high frequencies (HF, 3 - 30 MHz), very high frequencies (VHF, 30 - 300 MHz) and ultra high frequencies (UHF, 300 - 3000 MHz) have been used for long range and shortrange communications, for communication interference or for detection. To have all those functions on the same carrier, they require many antennas, therefore they are increasing the operator's electromagnetic overexposure risk. Civilian and military standards were published providing limits on external electromagnetic fields and dosimetric quantities (specific absortion rate SAR, current density and internal electric field) to limit this overexposure risk between 0 and 300 GHz. The PhD thesis project has two main objectives. First, civilian and military standards are studied to understand how they were developed and if they are really suited for HF and VHF frequencies. Second, a new validation method of Thales radio product is proposed and validated. This PhD thesis project have characterized numerically the human body electromagnetic and thermal behavior during electromagnetic exposure in HF and VHF. Then, by studying couplings between external electromagnetic fields, induced current and human body, formulas to calculate both whole-body averaged SAR and local SAR 10 g in homogeneous body are proposed for the first time. ; Dans les environnements militaires, et plus particulièrement dans le domaine terrestre, de nombreux systèmes radioélectriques HF (de 3 à 30 MHz), VHF (de 30 à 300 MHz) et UHF (de 300 à 3000 MHz) sont utilisés. Ces systèmes remplissent plusieurs fonctions (communication longue et courte distance, brouillage, radar, etc .) et peuvent parfois cohabiter sur un même porteur. Ces différentes fonctions utilisent plusieurs antennes et augmentent les risques de surexposition électromagnétique des opérateurs. Des normes civiles et militaires proposent des limites sur les champs électromagnétiques appliqués et sur des grandeurs dosimétriques (débit d'absorption spécifique DAS, densité de ...

In military environments, especially land field, high frequencies (HF, 3 - 30 MHz), very high frequencies (VHF, 30 - 300 MHz) and ultra high frequencies (UHF, 300 - 3000 MHz) have been used for long range and shortrange communications, for communication interference or for detection. To have all those functions on the same carrier, they require many antennas, therefore they are increasing the operator's electromagnetic overexposure risk. Civilian and military standards were published providing limits on external electromagnetic fields and dosimetric quantities (specific absortion rate SAR, current density and internal electric field) to limit this overexposure risk between 0 and 300 GHz. The PhD thesis project has two main objectives. First, civilian and military standards are studied to understand how they were developed and if they are really suited for HF and VHF frequencies. Second, a new validation method of Thales radio product is proposed and validated. This PhD thesis project have characterized numerically the human body electromagnetic and thermal behavior during electromagnetic exposure in HF and VHF. Then, by studying couplings between external electromagnetic fields, induced current and human body, formulas to calculate both whole-body averaged SAR and local SAR 10 g in homogeneous body are proposed for the first time. ; Dans les environnements militaires, et plus particulièrement dans le domaine terrestre, de nombreux systèmes radioélectriques HF (de 3 à 30 MHz), VHF (de 30 à 300 MHz) et UHF (de 300 à 3000 MHz) sont utilisés. Ces systèmes remplissent plusieurs fonctions (communication longue et courte distance, brouillage, radar, etc .) et peuvent parfois cohabiter sur un même porteur. Ces différentes fonctions utilisent plusieurs antennes et augmentent les risques de surexposition électromagnétique des opérateurs. Des normes civiles et militaires proposent des limites sur les champs électromagnétiques appliqués et sur des grandeurs dosimétriques (débit d'absorption spécifique DAS, densité de courant et champs électriques internes) pour limiter ces risques entre 0 et 300 GHz. Ces travaux de thèse ont deux objectifs principaux. Le premier est d'étudier les normes civiles et militaires afin de comprendre comment elles ont été développées et si elles sont réellement adaptées aux fréquences HF et VHF. Le deuxième est de proposer et valider une nouvelle méthode de validation des produits radio Thales. Pour cela, nous caractérisons numériquement le comportement électromagnétique et thermique du corps humain lors d'une exposition électromagnétique en bandes HF et VHF. L'étude des couplages entre le corps et les champs électromagnétiques externes nous permet de proposer pour la première fois des formules calculant les DAS dans le corps d'un fantôme homogène à partir, soit des courants induits le long du corps pour une exposition quelconque, soit du champ électrique appliqué pour une exposition en onde plane.

In Benin, terrestrial ecosystems are polluted by a widespread presence of pesticide residues released by an intensive use of plant protection products in agriculture, mainly those sprayed on cotton crops. In order to assess the exposure of producers to pesticides and predict the potential impact on human health, field observation of local practices coupled with semi-structured surveys were conducted among 150 cotton growers in Gogounou, Kandi and Banikoara in Northern Benin, the main cotton production area of the country. Seventy-five percent of producers never received an education nor instructions of use, while only 5% have been trained in the safe use of pesticides on cotton crops. Among pesticides used by farmers, only 19% belong to the approved list of plant protection products in Benin. The most frequently used active substances are insecticides such as acetamiprid, lambda-cyhalothrin, chlorpyrifos-ethyl, emamectin benzoate, profenofos or cypermethrin. All are known to be more or less toxic and may have detrimental effects on health after exposure. Seventy-five percent of producers use higher amounts of insecticides than recommended on the labels and 80% do not wear personal protective equipment during mixing, loading and spraying. Empty pesticide containers are often left in cotton fields (73% of observations) or sometimes used for domestic purposes (25% of observations). Field observations were translated into reliable scenarios to estimate the exposure levels of producers, using the UK-POEM predictive model. Total exposures without personal protective equipment vary from 0.099 to 0.546 mg/kg body weight/day. Exposure values far exceed the Acceptable Operator Exposure Levels, indicating a potential risk.

Nowadays, timber structures are well on the way to democratization as regards building uses. They, indeed, present many advantages including light weight, speed of implementation and contribution to sustainable development. These structures are made of timber elements connected together using metal components such as bolts, dowels and nails forming the mechanical joints, which is sometimes reinforced with metal plates. Consequently, the joints are vulnerable areas when exposed to fire. Understanding their mechanical behavior, therefore, is essential, not only as regards fire exposure, but also as regards the coupling of the thermal and hydric fluxes within the connections.As we know, wood is an anisotropic material and relatively humid. The combination of the architectural demand and the material mechanical resistance requires wood materials to cohabit with other materials like steel fasteners. With the presence of steel members, thermo -hydric heat transfer phenomena within joints under fire exposure increase in speed and complexity [4 e7].This complexity comes from the difference between the materials regarding mechanical rigidity and thermo -hydric permeability. It affects the mechanical and thermo-physical properties of the materials eventually, in particular, thermal conductivity and specific heat subjected to the thermal action of fire. With this aim in view, the present research provides important experimental and numerical data, which are needed in the field of understanding and quantifying thermos-hydric transfer phenomenon within timber-steel connections.The objective of this thesis is to present the findings of the investigations carried out to study experimental and numerical thermo-hydric transfer of timber connections subjected to the ISO-834 standard conditions of fire exposure. The experimental part starts by the study of a sin gle bolt or single dowel timber-timber connections under fire. The temperature-time evolutions are measured at different places of the connections. Then two studies are ...

An improbable scandal. Asbestos exposures : from an occupational disease to a « public health crisis » Combining information science and media studies, sociology and political science, this thesis attempts to understand the processes that transform an issue from a socially ignored question to a public scandal, and at the same time to show the importance of its framing in stabilized discursive patterns of « scandalisation » by media. The issue of asbestos exposures is a privileged ground of observation since it is the only contemporary example of public crisis made up starting from mainly occupational diseases. After the analysis of the way in which, from 1980 to 1994, are normalized the consequences of asbestos exposures by a double mechanism of social containment of the sufferings and localization of the knowledge, this work accounts for the history of the development of the public crisis around this problem over the period 1994-1996 in France. The aim is to avoid two kinds of explanation having often course to analyze the emergence of public crises : the granting of a central role to the group of journalists presented like building in an autonomous way discourses on an issue and the recourse to a conspiracy theory explaining the periods of silence and strong publicity by the occult influence of lobbies. To avoid these explanatory frames, it is necessary to give greater importance to the analysis of the regular interactions between journalists and the social groups mobilized or concerned about a problem, to show the dependence of the group of journalists on their sources, and to replace the question of publicizing or no-publicizing in games of knowledge/lack of knowledge and interest/disinterest implying very vast fields of the society. Lastly, this thesis reconsiders the question of agenda-setting and reviews the consequences of the publicizing process of an issue on its answer by political and administrative actors. ; A l'intersection des sciences de l'information et de la communication, de la sociologie et ...

Combining information science and media studies, sociology and political science, this thesis attempts to understand the processes that transform an issue from a socially ignored question to a public scandal, and at the same time to show the importance of its framing in stabilized discursive patterns of « scandalisation » by media. The issue of asbestos exposures is a privileged ground of observation since it is the only contemporary example of public crisis made up starting from mainly occupational diseases. After the analysis of the way in which, from 1980 to 1994, are normalized the consequences of asbestos exposures by a double mechanism of social containment of the sufferings and localization of the knowledge, this work accounts for the history of the development of the public crisis around this problem over the period 1994-1996 in France. The aim is to avoid two kinds of explanation having often course to analyze the emergence of public crises : the granting of a central role to the group of journalists presented like building in an autonomous way discourses on an issue and the recourse to a conspiracy theory explaining the periods of silence and strong publicity by the occult influence of lobbies. To avoid these explanatory frames, it is necessary to give greater importance to the analysis of the regular interactions between journalists and the social groups mobilized or concerned about a problem, to show the dependence of the group of journalists on their sources, and to replace the question of publicizing or no-publicizing in games of knowledge/lack of knowledge and interest/disinterest implying very vast fields of the society. Lastly, this thesis reconsiders the question of agenda-setting and reviews the consequences of the publicizing process of an issue on its answer by political and administrative actors. ; A l'intersection des sciences de l'information et de la communication, de la sociologie et de la science politique, cette thèse s'attache à comprendre les mécanismes qui font passer un problème ...

Combining information science and media studies, sociology and political science, this thesis attempts to understand the processes that transform an issue from a socially ignored question to a public scandal, and at the same time to show the importance of its framing in stabilized discursive patterns of « scandalisation » by media. The issue of asbestos exposures is a privileged ground of observation since it is the only contemporary example of public crisis made up starting from mainly occupational diseases. After the analysis of the way in which, from 1980 to 1994, are normalized the consequences of asbestos exposures by a double mechanism of social containment of the sufferings and localization of the knowledge, this work accounts for the history of the development of the public crisis around this problem over the period 1994-1996 in France. The aim is to avoid two kinds of explanation having often course to analyze the emergence of public crises : the granting of a central role to the group of journalists presented like building in an autonomous way discourses on an issue and the recourse to a conspiracy theory explaining the periods of silence and strong publicity by the occult influence of lobbies. To avoid these explanatory frames, it is necessary to give greater importance to the analysis of the regular interactions between journalists and the social groups mobilized or concerned about a problem, to show the dependence of the group of journalists on their sources, and to replace the question of publicizing or no-publicizing in games of knowledge/lack of knowledge and interest/disinterest implying very vast fields of the society. Lastly, this thesis reconsiders the question of agenda-setting and reviews the consequences of the publicizing process of an issue on its answer by political and administrative actors. ; A l'intersection des sciences de l'information et de la communication, de la sociologie et de la science politique, cette thèse s'attache à comprendre les mécanismes qui font passer un problème ...

Uranium is a radioactive heavy metal found in the environment. Due to its natural presence and to civil and militaries activities, general population can be exposed to U throughout drinking water or contaminated food. The pro/anti-oxidative system is a defense system which is often implicated in case of acute exposure to U. The aim of this thesis is to study the role of the pro/anti-oxidative system after chronic exposure to U in the liver and the kidney. After chronic exposure of rats to different U concentrations, this radionuclide accumulated in the organs in proportion to U intake; until 6 µg.g-1 of kidney tissues. U is localized in nucleus of the proximal tubular cells of the kidney. No nephrotoxicity was described even for the higher U level in drinking water and a reinforcement of the pro/anti-oxidative system with an increase in glutathione is observed. The study of U internal contamination in Nrf2 deficient mice, a cytoprotective transcription factor involved in the anti-oxidative defense has been realized. U accumulate more in Nrf2 -/- mice than in WT mice but the biologic effects of U on the pro/anti-oxidative system did not seem to implicate Nrf2. At the cell level, a correlation between U distribution in HepG2 cells and the biological effects on this system is observed after U exposure at low concentrations. Soluble distribution of U is observed in cell nucleus. The apparition of U precipitates is correlated to the establishment of the adaptive mechanisms overtime which are overwhelmed and lead to a cellular toxicity at higher U level. In conclusion, these results suggest that the reinforcement of pro/anti-oxidative system could be an adaptive mechanism after chronic exposure at low U concentration. ; L'Uranium (U) est un métal lourd radioactif dispersé dans l'environnement. Du fait de cette présence naturelle mais aussi de ses applications civiles et militaires, la population générale peut être exposée à l'U par ingestion d'eau de boisson ou d'aliments contaminés. Le système pro/anti-oxydant est un ...