Diversité des approches de modélisation statistique en analyse de réseaux sociaux multiniveaux

Cet article présente différentes approches statistiques combinant l’analyse multiniveau et l’analyse de réseaux sociaux, allant des modèles p2 multiniveau pour l’analyse de données de réseaux égocentrées aux Exponential Random Graph Models (ERGM) pour des données multiniveaux néostructurales. Nous développons premièrement les modèles stochastiques basés sur une dépendance dyadique, intégrant l’approche hiérarchique par une mise en parallèle de différentes expériences. Après avoir présenté la modélisation de type ERGM, nous nous demandons explicitement comment introduire de la dépendance « multiniveau » dans ces derniers. Nous terminons alors sur la formalisation proposée par Robins et Wang [2010] qui semble la plus aboutie pour traiter la dépendance verticale entre ces deux réseaux de niveaux différents, mais partiellement emboités

De la relación inter-individual a la relación inter-organizacional : un análisis de redes multinivel de un mercado de programas de televisión en África subsahariana

Hoy, el encastramiento de las actividades económicas en las relaciones sociales no parece ser un hecho a demostrar en el campo de la sociología económica. Sin embargo, ¿podemos concluir que un contrato comercial entre dos empresas está necesariamente encastrado en las relaciones sociales de sus miembros? Sobre la base de los conceptos de encastramiento y desacoplamiento de White, intentaremos analizar cómo las relaciones inter-individuales pueden convertirse en relaciones inter-organizacionales. El análisis de redes sociales multinivel constituye un marco teórico y metodológico para captar este fenómeno. Describiremos a través del estudio de una red multinivel de un salón de distribución de programas audiovisuales en África, la dinámica entre encastramiento y desacoplamiento que podemos observar en un mercado. Demostramos que en la medida en que los individuos participan más en este salón, más serán los contratos entre las empresas que están encastrados en sus redes.L'encastrement des activités économiques dans les relations sociales ne semble plus aujourd'hui un fait à prouver dans le champ de la sociologie économique. Pourtant, pouvons-nous en conclure qu'un contrat commercial entre deux entreprises est nécessairement encastré dans les relations sociales de leurs membres ? En nous inspirant des concepts d'encastrement et découplage de White, nous chercherons ainsi à analyser comment des relations inter-individuelles peuvent devenir des relations inter-organisationnelles. L'analyse de réseaux sociaux multiniveaux constitue un cadre théorique et méthodologique permettant de saisir ce phénomène. Nous décrirons ainsi à travers une étude de réseau multiniveaux d'un salon de distribution de programmes audiovisuels en Afrique, les dynamiques entre encastrement et découplage observables sur un marché. Nous montrons entre autres que plus les individus participent à ces salons, plus les contrats entre leurs entreprises sont encastrés dans leurs réseaux

Calibration and evaluation of optical systems for full-field strain measurement

The design and testing of a reference material for the calibration of optical systems for strain measurement is described, together with the design and testing of a standardized test material that allows the evaluation and assessment of fitness for purpose of the most sophisticated optical system for strain measurement. A classification system for the steps in the measurement process is also proposed and allows the development of a unified approach to diagnostic testing of components or sub-systems in an optical system for strain measurement based on any optical technique. The results described arise from a European study known as SPOTS whose objectives were to begin to fill the gap caused by a lack of standards

Strategic outsourcing and precision agriculture: towards a silent reorganization of agricultural production in France ?

In France as in other European countries, farm outsourcing has been developing for the past twenty years. Today, this phenomenon concerns both small and large farms. What is surprising is the growing number of farmers who outsource precision farming operations that involve sophisticated technologies and specialized expertise. This stylized fact is rather counter-intuitive to the known result of transaction cost theory, according to which in the presence of specific assets, ownership prevails over outsourcing. The objective of our study is to analyze the determinants of these new agricultural outsourcing practices associated with precision agriculture. We start with the transaction costs and property rights frameworks, then discuss recent theoretical contributions of relational contracts to explain the possibility of outsourcing in the presence of high asset specificity. Empirical evidences are provided for France using a mixed research methodology. Based on original data from surveys of 1200 farmers and of 20 of medium and large custom operators, our methodology combines an estimation of discrete choice models of outsourcing for different levels of asset specificity and case studies of major farm outsourcing organizational schemes. Our results show that in the presence of high specific assets, outsourcing can be preferred to ownership for strategic reasons. This phenomenon is counter-intuitive from the point of view of transaction cost theory, but is possible when one considers possible ex-ante incentive mechanisms (expectation of specialization gains, inclusion of a bonus based on the value of the output in the formal contract, participation of a third party), and informal incentive mechanisms built through repeated interactions

Геологическое строение, нефтегазоносность и подсчет запасов газа пласта ПК1 Антипаютинского газового месторождения (ЯНАО)

На основе комплексной интерпретации данных сейсморазведки 3D, данных ГИС и испытания пласта в разведочных скважинах обосновано геологическое строение газовой залежи пласта ПК1 Антипаютинского месторождения. Проведен обобщающий анализ результатов лабораторных исследований кернов, пластовых флюидов, промыслово-геофизических и газогидродинамических исследований изучаемого объекта. Построены карты кровли коллекторов пласта ПК1, поверхности межфлюидного контакта, эффективных газонасыщенных толщин пласта. Дано обоснование подсчётных параметров, определяемых по данным ГИС (коэффициенты пористости, газонасыщенности, эффективные газонасыщенные толщины). На основе построенной детальной геологической модели проведён дифференцированный подсчёт запасов газа.On the basis of complex interpretation this seismic exploration 3D, data of GIS and test of layer in prospecting wells the geological structure of a gas deposit of PK1 layer of the Antipayutinsky field is proved. The generalizing analysis of results of laboratory researches of cores, formation fluids, trade and geophysical and gas-hydrodynamic researches of the studied object is carried out. Cards of a roof of collectors of PK1 layer, a surface of interfluid contact, effective gas-saturated thickness of layer are constructed. Justification of the subcalculating parameters determined by data of GIS (coefficients of porosity, gas saturation, effective gas-saturated thickness) is given. On the basis of the constructed detailed geological model the differentiated calculation of reserves of ga

Inhibin B and anti-Müllerian hormone as markers of gonadal function after hematopoietic cell transplantation during childhood

<p>Abstract</p> <p>Background</p> <p>It is difficult to predict the reproductive capacity of children given hematopoietic cell transplantation (HCT) before pubertal age because the plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are not informative and no spermogram can be done.</p> <p>Methods</p> <p>We classified the gonadal function of 38 boys and 34 girls given HCT during childhood who had reached pubertal age according to their pubertal development and FSH and LH and compared this to their plasma inhibin B and anti-Müllerian hormone (AMH).</p> <p>Results</p> <p>Ten (26%) boys had normal testicular function, 16 (42%) had isolated tubular failure and 12 (32%) also had Leydig cell failure. All 16 boys given melphalan had tubular failure. AMH were normal in 25 patients and decreased in 6, all of whom had increased FSH and low inhibin B.</p> <p>Seven (21%) girls had normal ovarian function, 11 (32%) had partial and 16 (47%) complete ovarian failure. 7/8 girls given busulfan had increased FSH and LH and 7/8 had low inhibin B. AMH indicated that ovarian function was impaired in all girls.</p> <p>FSH and inhibin B were negatively correlated in boys (P < 0.0001) and girls (P = 0.0006). Neither the age at HCT nor the interval between HCT and evaluation influenced gonadal function.</p> <p>Conclusion</p> <p>The concordance between FSH and inhibin B suggests that inhibin B may help in counselling at pubertal age. In boys, AMH were difficult to use as they normally decrease when testosterone increases at puberty. In girls, low AMH suggest that there is major loss of primordial follicles.</p

Changes in metabolic parameters and cardiovascular risk factors after therapeutic control of acromegaly vary with the treatment modality. Data from the Bicêtre cohort, and review of the literature

CONTEXT: Untreated acromegaly is associated with increased morbidity and mortality due to malignant, cardiovascular, and cerebrovascular disorders. Effective treatment of acromegaly reduces excess mortality, but its impact on cardiovascular risk factors and metabolic parameters are poorly documented. AIM: We analyzed changes in cardiovascular risk factors and metabolic parameters in patients receiving various treatment modalities. PATIENTS AND METHODS: We retrospectively studied 96 patients with acromegaly, both at diagnosis and after IGF-I normalization following surgery alone (n = 51) or medical therapy with first generation somatostatin analogues (SSA, n = 23), or pegvisomant (n = 22). Duration of follow-up was 77 (42-161) months, 75 (42-112) months, and 62 (31-93) months, in patients treated with surgery alone, SSA, and pegvisomant, respectively. In all the cases except four, patients treated medically had underwent previous unsuccessful surgery. RESULTS: IGF-I normalization was associated with increased body weight, decreased systolic blood pressure (SBP) in hypertensive patients, decreased fasting plasma glucose (FPG) and HOMA-IR and HOMA-B levels, increased HDL cholesterol (HDLc); whereas, LDL cholesterol (LDLc) was not significantly different. Plasma PCSK9 levels were unchanged in patients with available values. Cardiovascular and metabolic changes varied with the treatment modality: surgery, but not pegvisomant, had a beneficial effect on SBP; FPG decreased after surgery but increased after SSA; the decline in HOMA-IR was only significant after surgery; pegvisomant significantly increased LDLc and total cholesterol; whereas SA increased HDLc and had no effect on LDLc levels. CONCLUSION: Treatments used to normalize IGF-I levels in patients with acromegaly could have differential effects on cardiovascular risk factors and metabolic parameters

Hypothalamic-pituitary-ovarian Axis Reactivation by Kisspeptin-10 in Hyperprolactinemic Women with Chronic Amenorrhea

CONTEXT : Hyperprolactinemia-induced hypogonadotropic amenorrhea (hPRL-HA) is a major cause of hypothalamic gonadotrophin-releasing hormone (GnRH) deficiency in women. In hyperprolactinemic mice, we previously demonstrated that hypothalamic kisspeptin (Kp) expression was diminished and that Kp administration restored hypothalamic GnRH release, gonadotropin secretion, and ovarian cyclicity, suggesting that Kp neurons could also play a role in hPRL-HA. OBJECTIVE : To study the effect of Kp-10 on the gonadotropic-ovarian axis in women with hPRL-HA. PATIENTS : Two women (32 and 36 years old) with chronic hPRL-HA (prolactin: between 94 and 102 and 98 and 112 ng/mL, respectively) caused by cabergoline-resistant microprolactinomas. INTERVENTIONS : Cabergoline was discontinued 6 months before inclusion. Blood samples were taken every 10 minutes for 12 hours during 2 consecutive days to evaluate luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion. Serum estradiol (E2), testosterone (T), and inhibin B (IB) levels were also measured. Vehicle or Kp-10 (1.5 mg/kg/h) was infused intravenously for 12 hours. RESULTS : Kp-10 induced a significant increase in LH and FSH levels and increased LH pulses. E2, T, and IB serum levels were also significantly increased. CONCLUSIONS : In this exploratory study, we demonstrated that administration of Kp-10 reactivated gonadotropin secretion in women with hPRL-HA and increased ovarian activity. Our data suggest that, as in rodents, GnRH deficiency in hPRL-HA is also mediated by an impairment of hypothalamic Kp secretion. Kp-10 or its analogues could have therapeutic application as an alternative approach to restore ovarian function and fertility in women with hPRL-HA resistant to dopamine agonists and in whom pituitary surgery is not possible.https://academic.oup.com/jesam2018ImmunologyPhysiolog