Turbulent Couette-Taylor flows with endwall effects: a numerical benchmark

International audienceThe accurate prediction of fluid flow within rotating systems has a primary role for the reliability and performance of rotating machineries. The selection of a suitable model to account for the effects of turbulence on such complex flows remains an open issue in the literature. This paper reports a numerical benchmark of different approaches available within commercial CFD solvers together with results obtained by means of in-house developed or open-source available research codes exploiting a suitable Reynolds Stress Model (RSM) closure, Large Eddy Simulation (LES) and a direct numerical simulation (DNS). The predictions are compared to the experimental data of Burin et al. (2010) in an original enclosed Couette-Taylor apparatus with endcap rings. The results are discussed in details for both the mean and turbulent fields. A particular attention has been turned to the scaling of the turbulent angular momentum G with the Reynolds number Re. By DNS, G is found to be proportional to Rea, the exponent a = 1.9 being constant in our case for the whole range of Reynolds numbers. Most of the approaches predict quite well the good trends apart from the k-w SST model, which provides relatively poor agreement with the experiments even for the mean tangential velocity profile. Among the RANS models, even though no approach appears to be fully satisfactory, the RSM closure offers the best overall agreement

Caractérisation de l'influence des instabilités de surface d'un film d'eau ruisselant sur le transfert de chaleur pariétal

Les films d'eau ruisselants sont utilisés dans un grand nombre d'applications industrielles. Ils permettent en impliquant une faible masse de fluide d'obtenir des transferts de chaleur importants. En général, ces films sont sujets à des instabilités de surface. Nous proposons ici une étude de l'influence de celles-ci sur le transfert convectif pariétal. Le problème est abordé numériquement en utilisant un maillage mobile épousant la forme de la surface libre. Une étude statistique nous permet de conclure sur l'importance des fluctuations de hauteur du film sur le flux pariétal transféré

Transferts de chaleur et de masse dans de ecoulements turbulents de Taylor-Couette avec flux axial

International audienceNous nous intéressons ici aux transferts de chaleur et de masse dans unsys eme de Taylor-Couette avec flux axial. Un dispositif permettant des mesures de vitesse et de coefficients de transferts á eté développé. Les régime etudiés sont turbulents : nombre de Reynolds axial entre 5600 et 11200 et entre 7900 et 79 millios pour le nombre de Taylor. Nous reportons le nombre de Nusselt en fonction du nombre de Reynolds axial et du nombre de Taylor ainsi que des mesures de vitesse. La présence de structures organisées proche du rotor á eté observée, ce qui est confirmé par un calcul DNS

Maternal wellbeing five years after a very preterm delivery: prevalence and influencing factors in a European cohort

(1) Background: Mothers of very preterm (VPT) infants may experience psychological symptoms compromising long-term emotional wellbeing. This study describes the emotional wellbeing of mothers of five-year-old children born VPT. We assess the association between sociodemographic, perinatal and neonatal characteristics, and the child’s health and development at five years old and maternal emotional wellbeing. (2) Methods: Data are from the prospective European “Effective Perinatal Intensive Care in Europe” (EPICE) and subsequent “Screening for Health In very Preterm infantS in Europe” (SHIPS) projects including births <32 weeks’ gestational age in 11 countries in 2011/12. Data were abstracted from obstetric and neonatal records. At five years old, 2605 mothers answered a parental questionnaire including the Mental Health Inventory-5 (MHI-5). Associations between sociodemographic and health characteristics and the mother’s MHI-5 score were investigated using multilevel multivariate linear regression analysis with the country modelled as a random effect and inverse probability weighting to correct for attrition bias. (3) Results: The mean MHI-5 score was 71.3 (SD 16.7) out of 100 (highest emotional wellbeing) with a variation among countries from 63.5 (SD 16.8; Poland) to 82.3 (SD 15.8; the Netherlands). MHI-5 scores were significantly lower for mothers whose child had a severe health problem, developmental, or speech delay, for multiparous and single mothers, and when at least one of the parents was unemployed. (4) Conclusions: The emotional wellbeing of mothers of VPT infants differs between European countries. Identifying sociodemographic characteristics and child’s health and developmental conditions that affect maternal emotional wellbeing may help to identify groups of mothers who need special assistance to cope with consequences of the delivery of a VPT child

Developmental motor problems and health-related quality of life in 5-year-old children born extremely preterm:A European cohort study

Aim: To measure the association between cerebral palsy (CP) and non-CP-related movement difficulties and health-related quality of life (HRQoL) among 5-year-old children born extremely preterm (&lt;28 weeks gestational age). Method: We included 5-year-old children from a multi-country, population-based cohort of children born extremely preterm in 2011 to 2012 in 11 European countries (n = 1021). Children without CP were classified using the Movement Assessment Battery for Children, Second Edition as having significant movement difficulties (≤5th centile of standardized norms) or being at risk of movement difficulties (6th–15th centile). Parents reported on a clinical CP diagnosis and HRQoL using the Pediatric Quality of Life Inventory. Associations were assessed using linear and quantile regressions. Results: Compared to children without movement difficulties, children at risk of movement difficulties, with significant movement difficulties, and CP had lower adjusted HRQoL total scores (β [95% confidence interval] = −5.0 [−7.7 to −2.3], −9.1 [−12.0 to −6.1], and − 26.1 [−31.0 to −21.2]). Quantile regression analyses showed similar decreases in HRQoL for all children with CP, whereas for children with non-CP-related movement difficulties, reductions in HRQoL were more pronounced at lower centiles. Interpretation: CP and non-CP-related movement difficulties were associated with lower HRQoL, even for children with less severe difficulties. Heterogeneous associations for non-CP-related movement difficulties raise questions for research about mitigating and protective factors.</p

Impact of parental lifestyle patterns in the preconception and pregnancy periods on childhood obesity

International audienceIntroduction High prevalence of overweight and obesity already observed in preschool children suggests the involvement of early-life risk factors. Preconception period and pregnancy are crucial windows for the implementation of child obesity prevention interventions with parental lifestyle factors as relevant targets. So far, most studies have evaluated their role separately, with only a few having investigated their potential synergistic effect on childhood obesity. Our objective was to investigate parental lifestyle patterns in the preconception and pregnancy periods and their association with the risk of child overweight after 5 years. Materials and methods We harmonized and interpreted results from four European mother-offspring cohorts participating in the EndObesity Consortium [EDEN, France; Elfe, France; Lifeways, Ireland; and Generation R, Netherlands] with data available for 1,900, 18,000, 1,100, and 9,500 families, respectively. Lifestyle factors were collected using questionnaires and included parental smoking, body mass index (BMI), gestational weight gain, diet, physical activity, and sedentary behavior. We applied principal component analyses to identify parental lifestyle patterns in preconception and pregnancy. Their association with risk of overweight (including obesity; OW-OB) and BMI z -scores between 5 and 12 years were assessed using cohort-specific multivariable logistic and linear and regression models (adjusted for potential confounders including parental age, education level, employment status, geographic origin, parity, and household income). Results Among the various lifestyle patterns derived in all cohorts, the two explaining the most variance were characterized by (1) “high parental smoking, low maternal diet quality (and high maternal sedentary behavior in some cohorts)” and, (2) “high parental BMI and low gestational weight gain.” Patterns characterized by high parental BMI, smoking, low diet quality or high sedentary lifestyle before or during pregnancy were associated with higher risk of OW-OB in children, and BMI z -score at any age, with consistent strengths of associations in the main cohorts, except for lifeways. Conclusion This project provides insight into how combined parental lifestyle factors in the preconception and pregnancy periods are associated with the future risk of child obesity. These findings are valuable to inform family-based and multi-behavioural child obesity prevention strategies in early life

Treating very preterm European infants with inhaled nitric oxide increased in-hospital mortality but did not affect neurodevelopment at 5 years of age

Aim: We examined the outcomes of using inhaled nitric oxide (iNO) to treat very preterm born (VPT) infants across Europe. Methods: This was a sub-study of the Screening to Improve Health in Very Preterm Infants in Europe research. It focused on all infants born between 22 + 0 and 31 + 6 weeks/days of gestation from 2011 to 2012, in 19 regions in 11 European countries. We studied 7268 infants admitted to neonatal care and 5 years later, we followed up the outcomes of 103 who had received iNO treatment. They were compared with 3502 propensity score-matched controls of the same age who did not receive treatment. Results: All countries used iNO and 292/7268 (4.0%) infants received this treatment, ranging from 1.2% in the UK to 10.5% in France. There were also large regional variations within some countries. Infants treated with iNO faced higher in-hospital mortality than matched controls (odds ratio 2.03, 95% confidence interval 1.33–3.09). The 5-year follow-up analysis of 103 survivors showed no increased risk of neurodevelopmental impairment after iNO treatment. Conclusion: iNO was used for VPT patients in all 11 countries. In-hospital mortality was increased in infants treated with iNO, but long-term neurodevelopmental outcomes were not affected in 103 5-year-old survivors

Development of a Multivariate Prediction Model for Early-Onset Bronchiolitis Obliterans Syndrome and Restrictive Allograft Syndrome in Lung Transplantation.

Chronic lung allograft dysfunction and its main phenotypes, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS), are major causes of mortality after lung transplantation (LT). RAS and early-onset BOS, developing within 3 years after LT, are associated with particularly inferior clinical outcomes. Prediction models for early-onset BOS and RAS have not been previously described. LT recipients of the French and Swiss transplant cohorts were eligible for inclusion in the SysCLAD cohort if they were alive with at least 2 years of follow-up but less than 3 years, or if they died or were retransplanted at any time less than 3 years. These patients were assessed for early-onset BOS, RAS, or stable allograft function by an adjudication committee. Baseline characteristics, data on surgery, immunosuppression, and year-1 follow-up were collected. Prediction models for BOS and RAS were developed using multivariate logistic regression and multivariate multinomial analysis. Among patients fulfilling the eligibility criteria, we identified 149 stable, 51 BOS, and 30 RAS subjects. The best prediction model for early-onset BOS and RAS included the underlying diagnosis, induction treatment, immunosuppression, and year-1 class II donor-specific antibodies (DSAs). Within this model, class II DSAs were associated with BOS and RAS, whereas pre-LT diagnoses of interstitial lung disease and chronic obstructive pulmonary disease were associated with RAS. Although these findings need further validation, results indicate that specific baseline and year-1 parameters may serve as predictors of BOS or RAS by 3 years post-LT. Their identification may allow intervention or guide risk stratification, aiming for an individualized patient management approach

Deriving the dietary approaches to stop hypertension (DASH) score in women from seven pregnancy cohorts from the European alphabet consortium

The ALPHABET consortium aims to examine the interplays between maternal diet quality, epigenetics and offspring health in seven pregnancy/birth cohorts from five European countries. We aimed to use the Dietary Approaches to Stop Hypertension (DASH) score to assess diet quality, but different versions have been published. To derive a single DASH score allowing cross-country, cross-cohort and cross-period comparison and limiting data heterogeneity within the ALPHABET consortium, we harmonised food frequency questionnaire (FFQ) data collected before and during pregnancy in ≥26,500 women. Although FFQs differed strongly in length and content, we derived a consortium DASH score composed of eight food components by combining the prescriptive original DASH and the DASH described by Fung et al. Statistical issues tied to the nature of the FFQs led us to re-classify two food groups (grains and dairy products). Most DASH food components exhibited pronounced between-cohort variability, including non-full-fat dairy products (median intake ranging from 0.1 to 2.2 servings/day), sugar-sweetened beverages/sweets/added sugars (0.3–1.7 servings/day), fruits (1.1–3.1 servings/day), and vegetables (1.5–3.6 servings/day). We successfully developed a harmonized DASH score adapted to all cohorts being part of the ALPHABET consortium. This methodological work may benefit other research teams in adapting the DASH to their study’s specificities