Sur l'analyse de réseaux de sociabilité de la société paysanne médiévale

National audienceL'histoire des sociétés rurales médiévales que nous connaissons a été construite à partir des traces qui nous sont parvenues, très souvent issues de la noblesse ou l'église de cette époque. De ce fait, le monde paysan, qui représente 90% de la population, est assez mal connu. L'étude d'une de ces sociétés, focalisée sur une zone géographique restreinte couverte par une documentation abondante, nous permet de reconstituer des réseaux de sociabilités. Nous analysons ces réseaux à l'aide d'outils de visualisation et nous montrons à la fois les changements structurels liés à des événements tels que les guerres et des analogies entre les graphes associés à ces réseaux et les graphes " petit monde "

Dosimetrie appliquee aux techniques d'ionisation par faisceaux d'electrons

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : TD 80873 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Absorbed dose to water determination for kilo-voltage X-rays using alanine/EPR dosimetry systems

International audienceAlanine's relative response to kilo-voltage X-rays, compared to 60 Co reference quality beam, was studied in this work, in order to determine correction factors to be applied to alanine's response when irradiated with low to medium energy X-rays (up to 300 keV). The relative response to kilo-voltage X-rays of Aerial's alanine dosimeters was determined by three distinct methods: experimental measurements using alanine dosimeters and a calibrated PTW Farmer 30013 ion chamber, Monte Carlo simulations using MCNPX code and finally, analytical calculations based on weighting of X-ray spectra by NIST's published mass energy absorption coefficients. Two sets of X-ray beam qualities, covering high voltages ranging from 50 kV up to 280 kV, were used to study the energy dependence of the alanine dosimeter's response. Obtained results were consistent within 2.1% (average standard deviation at k = 1)

Detection of irradiated ingredients included in low quantity in non-irradiated food matrix. 1. Extraction and ESR analysis of bones from mechanically recovered poultry meat

Protocol EN 1786 for the detection of irradiated food by electron spin resonance (ESR) spectroscopy was not conceived for the detection of irradiated bone-containing ingredients included in low concentration in non-irradiated food. An enzymatic hydrolysis method, realized at 55 degrees C, has been developed for the extraction of the bone fraction. When followed by a purification of the extracts by an aqueous solution of sodium polytungstate, this method made possible the detection of irradiated mechanically recovered poultry meat at very low inclusions (0.5%, wt/wt by ESR) in various meals (quenelles and precooked meals)

Detection of irradiated ingredients included in low quantity in non-irradiated food matrix. 2. ESR analysis of mechanically recovered poultry meat and TL analysis of spices

Protocols EN 1786 and EN 1788 for the detection of irradiated food by electron spin resonance spectroscopy (ESR) and thermoluminescence (TL) were not conceived for the detection of irradiated ingredients included in low concentration in nonirradiated food. An enzymatic hydrolysis method, realized at 55 degrees C, has been developed for the extraction of silicate minerals and bone fragments. When followed by a purification of the extracts by an aqueous solution of sodium polytungstate, this method made it possible to detect very low inclusions of irradiated spices (0.05%, wt/wt by TL) included in various meals (cheeses and precooked meals). Even for food containing together two ingredients (spices and mechanically recovered meat), it was possible to detect and identify them simultaneously

Degradation of profenofos in aqueous solution and in vegetable sample by electron beam radiation

International audienceIn this study, the role of accelerated electron irradiation on the removal of profenofos in aqueous solution and in peas was investigated. The samples were irradiated with a Rhodotron E-beam accelerator with 10 MeV energy at doses of 0 (control), 4.6, 12 and 32 kGy. Irradiated vegetable samples were extracted using a QuEChERS protocol (quick, easy, cheap, effective, rugged, and safe), allowing analysis of pesticide traces. Quantification of profenofos in aqueous solution was performed by using GC-MS in SIM mode and GC-MS/MS in MRM mode in vegetable sample. Degradation of profenofos increased with the E-beam dose and was much more important in aqueous solution than in vegetable. In irradiated aqueous solution, one degradation product was detected

Radical detection and electron‐spin resonance (<scp>ESR)</scp> monitoring in polymer materials irradiated with gamma and X‐rays: Polyethylene and polypropylene

International audienceWhen ionizing radiations interact with polymers, free radicals are generated and are known to be the initiating species for the modification in materials. Monitoring and identifying free radicals after irradiation allow assessing the impact of X-rays and gamma rays on materials. A comparative study has bee

Effects of a metallic implant on radiotherapy planning treatment—experience on a human cadaver

International audienceBackground: Metallic implants (MIs) complicate radiotherapy planning. Several studies have worked on tissue-equivalent phantoms as experimental models to estimate dose distributions in this context. The application of these results to clinical practice remains disputable because the inhomogeneity of human tissue densities is a difficult factor to integrate into dose calculation software. In this work, we evaluate the impact of human tissue inhomogeneities by assessing the discrepancies between treatment planning system (TPS) dose calculations and measured delivered doses on a human cadaver with hip prostheses.Methods: A total of 143 alanine dosimeters were positioned in contact with the prostheses (bones group), soft tissues (soft tissues group), skin surfaces (skin group) and natural cavities (cavities group) of a human cadaver. The planning target volume (PTV) corresponded to a standard endometrial cancer treatment. The irradiation was performed with 6 MV X-ray tomotherapy at the one fraction-dose of 10 Gy.Results: A total of 140 dosimeters were analyzed. After applying a temperature correction coefficient to the measured doses, the global analysis of all dosimeters showed a significant difference between the calculated doses and the measured doses (P<0.001). For dosimeters of the bones, soft tissues, skin and cavities groups, this difference was also significant (P<0.001 for each group). The mean measured doses were 21.9% lower than the mean calculated doses in the global analysis and 17.0%, 21.2%, 33.0% and 19.0% lower for the bones, soft tissues, skin and cavities groups, respectively.Conclusions: This study showed that the received doses were significantly lower than the calculated doses and suggested the need to improve the understanding of this discrepancy