La formation des doctorants à l'information scientifique et technique

La formation des doctorants aux problématiques de l'information scientifique et technique représente un enjeu particulièrement sensible pour l'enseignement supérieur et la recherche en France. Doublement affectée par de profondes transformations institutionnelles ainsi que par l'évolution accélérée des technologies numériques, la culture de l'information scientifique demeure l'un des piliers fondamentaux de la recherche et un élément incontournable dans la mise en œuvre d'une politique éclairée. La plupart des domaines d'activité du chercheur sont concernés : l'investigation, la propriété intellectuelle, la recherche documentaire, l'écriture scientifique, la publication, la communication scientifique, l'évaluation, les évolutions et les opportunités offertes par les outils numériques, la vulgarisation scientifique… Cet ouvrage se propose de poser quelques jalons afin d'alimenter la réflexion des divers protagonistes, universitaires, documentalistes, bibliothécaires, qui interviennent auprès du doctorant pour l'informer ou le guider tout au long de son parcours : quels seraient les attentes des doctorants et les besoins du monde académique ? Quelles connaissances et compétences les formateurs ont-ils à mobiliser ? Quels enseignements tirer des expériences et dispositifs mis en place ? Autant de questions pour approcher une thématique à la morphologie complexe. Le débat qu'elles suscitent met en lumière un bilan riche en interrogations et fécond pour l'avenir

Étude numérique de la répartition des contraintes dans des plaques de gousset de pylônes à treillis

Ce document présente un projet de recherche de maîtrise portant sur l’étude de la répartition des contraintes dans les plaques de gousset de pylônes à treillis, à la suite du souhait des partenaires industriels Hydro-Québec et RTE cherchant à mieux évaluer la résistance mécanique des pylônes à treillis. La fiabilité des plaques de gousset est questionnée, dû à l’absence de méthodes d’analyse détaillées de ces plaques de gousset, et dans le contexte où de nombreux efforts cheminent par ces plaques. L’intérêt est alors de représenter le plus fidèlement possible, le comportement des plaques de gousset de pylônes à treillis pour permettre de vérifier les règles de dimensionnement actuelles communément utilisées pour le dimensionnement des plaques de gousset, et d’améliorer par la suite ces règles. Les plaques de gousset sont généralement dimensionnées selon des règles d’ingénierie empiriques dépendant des gestionnaires de réseaux. Ces règles de dimensionnement ne permettent pas de faire une conception optimisée ni de connaître le niveau de fiabilité réel des plaques, qui peut être très variable selon la géométrie de la plaque et la complexité du chargement. Les règles de dimensionnement fournies que ce soit par l’Eurocode, le CSA S16-14 ou encore l’ASCE 10-15 ne sont pas adaptées aux plaques de gousset de pylônes à treillis, car les quelques calculs sommaires qui y sont proposés ne tiennent pas compte de l’ensemble des modes de ruines potentiels et de la complexité de la répartition des contraintes dans ces éléments structuraux. Ainsi compte tenu de l’importance des pylônes à treillis de transport d’énergie électrique, une recherche plus poussée sur le comportement des assemblages boulonnés de plaques de gousset est à prendre en considération. L’objectif de ce projet est de réaliser une modélisation numérique par éléments finis décrivant avec le plus de fiabilité la répartition des contraintes internes dans une plaque de gousset de pylône à treillis. Le développement de cette stratégie de modélisation se base sur le logiciel CODE_ASTER. Une validation du modèle numérique à l’aide des résultats de la bibliographie a permis de vérifier l’effet de certaines hypothèses simplificatrices sur le modèle. Ensuite, une étude paramétrique sur l’influence de plusieurs paramètres sur le comportement des plaques de gousset de pylônes à treillis a permis d’extraire les paramètres géométriques clés pour l’évaluation du comportement des contraintes dans les plaques. Cela a permis une d’obtenir une meilleure compréhension de la répartition des contraintes dans les plaques de gousset de pylônes à treillis

Orocline and syntaxes formation during subduction and collision

International audiencepresent work investigates the formation of curved ranges and syntaxes with scaled laboratory experiments. We simulated subduction and collision processes comparable to India-Asia configuration involving a continental upper plate and a subducting plate composed of an oceanic lithosphere and a continental indenter. The experiments reveal that the shape of the mountain range (concave, straight, or convex) and the development of syntaxes are controlled by the subduction interface, the buoyancy number (Fb) of the upper plate (i.e., thickness and viscosity), and the boundary conditions. Four end-members regimes of indentation can be defined depending on the range shape and dynamics of the upper plate. The curvature of the range is convex toward the subducting plate with syntaxes for a weak subduction fault and concave without syntaxes for a strong subduction fault. Convex curvature and syntaxes form by overthrusting of upper plate material on the subducting plate, which is faster at the center than at the extremities. They are associated with a rather flat slab (underthrusting) during continental collision. Low-Fb experiments show less pronounced curvatures associated to thickening comparable to the early stages of the India-Asia collision. In contrast, a thick and weak upper plate (high Fb) leads to gravity collapse that increases the amplitude of the curvature and lateral escape, similar to the late evolution of the Himalaya-Tibet system. Important lateral decoupling on the sides of the indenter enhances the indentation and produces sharper syntaxes

Worse Outcomes of Patients With HFE Hemochromatosis With Persistent Increases in Transferrin Saturation During Maintenance Therapy

International audienceBACKGROUND and AIMS: Even if patients with hemochromatosis maintain low serum levels of ferritin, they still have an increased risk of general and joint symptoms, which reduce quality of life. This could be related to persistently increased transferrin saturation. We assessed whether duration of exposure to increased transferrin saturation during maintenance therapy is associated with more severe general and joint symptoms.METHODS: We performed a longitudinal cohort study of 266 individuals homozygous for the C282Y substitution in HFE, seen at a tertiary reference center in Rennes, France, and followed for 3 or more years after initial iron removal. Serum ferritin and transferrin saturation were measured at the same time points; values were used to calculate duration of exposure to serum ferritin 50 mu g/L or more (FRT50exp) and to determine transferrin saturation 50% or greater (SAT50exp). Clinical and biochemical follow-up data were recorded from log books completed during maintenance therapy. The primary outcome was change in general and joint symptoms, determined from answers to a self-administered questionnaire.RESULTS: Patients were followed for 13.5 +/- 5.9 years. FRT50exp (3.2 +/- 3.5 years) and SAT50exp (4.5 +/- 3.4 years) values correlated (r = 0.38; P less than .0001), but each associated with different variables in multivariate analysis. We found independent associations, regardless of follow-up time, between SAT50exp >= 6 years and worsened joint symptoms (odds ratio [OR], 4.19; 95% confidence interval [CI], 1.88-9.31), and between SAT50exp >= 6 years and decreased athletic ability (OR, 2.35; 95% CI, 1.16-4.73). SAT50exp >= 8 years associated independently with decreased work ability (OR, 3.20; 95% CI, 1.40-7.30) and decreased libido (OR, 3.49; 95% CI, 1.56-7.80).CONCLUSIONS: In a longitudinal study of patients treated for hemochromatosis, we associated duration of exposure to increased transferrin saturation (longer than 6 years) with more severe general and joint symptoms. Maintenance of serum levels of ferritin at 50 mu g/L or less does not indicate control of transferrin saturation, so guidelines on the management of hemochromatosis require revision

The iron reabsorption index: a new phenotypic and pathophysiological descriptor in HFE hemochromatosis.

International audienceBACKGROUND: The current phenotypic descriptors of high Fe gene hemochromatosis are hardly specific and time dependent in a context of highly variable expressivity. We hypothesized that the rate of iron removed during maintenance therapy and corresponding to the iron reabsorption index (IRI) could be patient specific and may then represent a new useful phenotypic marker. AIM: The present study aimed to describe IRI with respect to its phenotypic specificity and to its potential usefulness. METHODS: We studied a cohort of 316 p.Cys282Tyr homozygous patients with stable low serum ferritin levels on maintenance therapy for at least 12 months. Characteristics at diagnosis, date and volume of phlebotomies, and parameters of iron metabolism throughout maintenance therapy were determined. RESULTS: IRI ranged from 1.3 to 6.1 mg/day (median: 2.44). It was lower in women (difference: 1.26 mg/day), mainly explained by physiological blood loss, weight, and alcohol consumption. IRI was correlated to iron burden and fibrosis stage at diagnosis, was stable over time (variation: 11.5%), and depended on serum ferritin level during therapy. CONCLUSION: Its independence from disease duration, its stability, its wide distribution, and its significant correlation with iron burden markers make IRI a valuable potential phenotypic indicator of the daily iron overabsorption in hemochromatosis. Moreover, IRI provides a conceptual frame for empiric adaptation of maintenance therapy

Reduced phenotypic expression in genetic hemochromatosis with time role of exposure to nongenetic modifiers

International audienceBackground & aims - Genetic hemochromatosis is mainly related to the homozygous p.Cys282Tyr (C282Y) mutation in the HFE gene, which causes hepcidin deficiency. Its low penetrance suggests the involvement of cofactors that modulate its expression. We aimed to describe the evolution of disease presentation and of non-genetic factors liable to impact hepcidin production in the long term. Methods - Clinical symptoms, markers of iron load, and risk factors according to the year of diagnosis were recorded over 30 years in a cohort of adult C282Y homozygotes. A total of 2,050 patients (1,460 probands [804 males and 656 females] and 542 relatives [244 males and 346 females]) were studied. Results - Over time: (i) the proband-to-relative ratio remained roughly stable; (ii) the gender ratio tended towards equilibrium among probands; (iii) age at diagnosis did not change among males and increased among females; (iv) the frequency of diabetes and hepatic fibrosis steadily decreased while that of chronic fatigue and distal joint symptoms remained stable; (v) transferrin saturation, serum ferritin and the amount of iron removed decreased; and (vi) the prevalence of excessive alcohol consumption decreased while that of patients who were overweight increased. Tobacco smoking was associated with increased transferrin saturation. Conclusion - Genetic testing did not alter the age at diagnosis, which contrasts with the dramatic decrease in iron load in both genders. Tobacco smoking could be involved in the extent of iron loading. Besides HFE testing, which enables the diagnosis of minor forms of the disease, the reduction of alcohol consumption and the increased frequency of overweight patients may have played a role in the decreased long-term iron load, as these factors are likely to improve hepcidin production. Lay summary - Genetic hemochromatosis is an inherited disorder that leads to progressive iron overload in the body. It results in chronic fatigue and in potential liver (cirrhosis), pancreas (diabetes) and joint (arthritis) damage in adulthood. The present study showed that tobacco smoking may aggravate iron loading, but that hemochromatosis has become less and less severe over the last 30 years despite patients being older at diagnosis, likely because of the protective effects of lower alcohol consumption and of increased weight in the French population

Decreased iron burden in overweight C282Y homozygous women: Putative role of increased hepcidin production.

International audienceAn excess of visceral adipose tissue could be involved as a modulator of the penetrance of HFE hemochromatosis since fat mass is associated with overexpression of hepcidin and low transferrin saturation was found to be associated with being overweight in women. This study was aimed at assessing the relationship between body mass index (BMI), a surrogate marker of insulin resistance, and iron burden in HFE hemochromatosis. In all, 877 patients from a cohort of C282Y homozygotes were included in the study when BMI at diagnosis and amount of iron removed (AIR) by phlebotomy were available. No relationship between AIR and BMI was found in men, whereas 15.1% (52/345) of women with AIR <6 g had BMI ≥28 versus 3.9% (2/51) of women with AIR ≥6 g (P = 0.03). At multivariate analysis, BMI was an independent factor negatively associated with AIR (odds ratio: 0.13; 95% confidence interval [CI]: 0.03-0.71) together with serum ferritin, serum transferrin, transferrin saturation, hemoglobin, and alanine aminotransferase. In a control group of 30 C282Y homozygous women, serum hepcidin was significantly higher in overweight (14.3 mmoL/L ± 7.1) than in lean (7.9 mmoL/L ± 4.3) women (P = 0.0005). Conclusion: In C282Y homozygous women, BMI ≥28 kg/m(2) is independently associated with a lower amount of iron removed by phlebotomy. BMI is likely a modulator factor of the phenotypic expression of C282Y homozygosity, likely through an increase of circulating levels of hepcidin. (HEPATOLOGY 2013;)

A multi-disciplinary approach to treating hepatitis C with interferon and ribavirin in alcohol-dependent patients with ongoing abuse.

International audienceBACKGROUND & AIMS: Guidelines recommend 6 months of alcohol abstinence before treating hepatitis C (HCV). Abstinence is difficult for alcohol-dependent patients to achieve. This study evaluated HCV treatment in alcoholic patients with ongoing consumption or less than 6 months of abstinence. METHODS: A multidisciplinary management model was built by a liver unit and two centers involved in the care of addict patients. Patients were included in a prospective observational study of treatment with pegylated interferon and ribavirin if they presented alcohol dependence with ongoing intoxication or abstinence of less than 6 months. Pre-therapeutic evaluation and follow-up were multidisciplinary, and addiction care was personalized to patient condition and willingness. Alcohol abstinence or reduction was encouraged but not mandatory. The primary end point was sustained virological response (SVR). Results were compared to a control group of patients matched for genotype, viral load, fibrosis stage, sex, and age. RESULTS: A total of 73 patients treated between 2002 and 2008 were included in the study. Intent to treat analysis showed an SVR in 48% (35/73) of patients versus 49% (36/73) of controls. Low viral load and length of abstinence during treatment were independently associated with SVR. During treatment, 20 (27%) patients were abstinent, 23 (32%) had controlled consumption, and 24 (33%) had excessive consumption. At the end of the follow-up, 22 (30%) patients were durably abstinent. CONCLUSIONS: A multidisciplinary approach allowed HCV treatment in alcohol-dependent patients with a satisfactory SVR rate and positive effects on addiction behavior

Decreased Cardiovascular and Extrahepatic Cancer-Related Mortality In Treated Patients with Mild HFE Hemochromatosis.

International audienceBackground & aims - Mortality studies in patients with hemochromatosis give conflicting results especially with respect to extrahepatic causes of death. Our objective was to assess mortality and causes of death in a cohort of patients homozygous for the C282Y mutation in the HFE gene, diagnosed since the availability of HFE testing. Methods - We studied 1085 C282Y homozygotes, consecutively diagnosed from 1996 to 2009, and treated according to current recommendations. Mortality and causes of death were obtained from death certificates and compared to those of the general population. Standardized mortality ratios (SMRs) were used to assess specific causes of death and the Cox model was used to identify prognostic factors for death. Results - Patients were followed for 8.3±3.9 years. Overall the SMR was the same as in the general population (0.94 CI: 0.71-1.22). Patients with serum ferritin⩾2000 μg/L had increased liver-related deaths (SMR: 23.9 CI: 13.9-38.2), especially due to hepatic cancer (SMR: 49.1 CI: 24.5-87.9). Patients with serum ferritin between normal and 1000 μg/L had a lower mortality than the general population (SMR: 0.27 CI: 0.1-0.5), due to a decreased mortality, related to reduced cardiovascular events and extrahepatic cancers in the absence of increased liver-related mortality. Age, diabetes, alcohol consumption, and hepatic fibrosis were independent prognostic factors of death. Conclusions - In treated HFE hemochromatosis, only patients with serum ferritin higher than 2000 μg/L have an increased mortality, mainly related to liver diseases. Those with mild iron burden have a decreased overall mortality in relation to reduced cardiovascular and extrahepatic cancer-related events. These results support a beneficial effect of early and sustained management of patients with iron excess, even when mild

Acoustic radiation force impulse imaging for assessing liver fibrosis in alcoholic liver disease

International audienceAIM: To evaluate the performance of elastography by ultrasound with acoustic radiation force impulse (ARFI) in determining fibrosis stage in patients with alcoholic liver disease (ALD) undergoing alcoholic detoxification in relation to biopsy. METHODS: Eighty-three patients with ALD undergoing detoxification were prospectively enrolled. Each patient underwent ARFI imaging and a liver biopsy on the same day. Fibrosis was staged according to the METAVIR scoring system. The median of 10 valid ARFI measurements was calculated for each patient. RESULTS: Sixty-nine males and thirteen females (one patient excluded due to insufficient biopsy size) were assessed with a mean alcohol consumption of 132.4 ± 128.8 standard drinks per week and mean cumulative year duration of 17.6 ± 9.5 years. Sensitivity and specificity were respectively 82.4% (0.70-0.95) and 83.3% (0.73-0.94) (AUROC = 0.87) for F ≥ 2 with a cut-off value of 1.63m/s; 82.4% (0.64-1.00) and 78.5% (0.69-0.89) (AUROC = 0.86) for F ≥ 3 with a cut-off value of 1.84m/s; and 92.3% (0.78-1.00] and 81.6% (0.72-0.90) (AUROC = 0.89) for F = 4 with a cut-off value of 1.94 m/s. CONCLUSION: ARFI is an accurate, non-invasive and easy method for assessing liver fibrosis in patients with ALD undergoing alcoholic detoxificatio