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International audience; The buckling of rate dependent structures is not a topic often discussed in the literature. Methods to predict the buckling of such structures exist, but only few experimental works have been published, and even less when considering thick shell structures. In this work we are interested in the buckling of thick elasto-visco-plastic hemi-egg shells. We follow a modeling/experimental approach to analyse such problem. Buckling experiments at room temperature on hemi-egg shells subjected to external pressure are performed. 3D digital image correlation is used to measure the displacement fields on the inner surface of the hemi-egg shell during the buckling experiments. Due to the specimen shape and their loading, they experience non-proportional load paths. The effect of a non-proportional load path on the buckling behaviour has already been discussed many times in the literature for elasto-plastic materials. This work also intends to assess this point for a rate dependent material. A buckling prediction model is used to predict the buckling of hemi-egg shells. This model couples Bodner's approach with the deformation theory. It is used to estimate the buckling critical times and the buckling modes based on a preliminary finite element analysis. The effects of geometrical and loading imperfections on the buckling behaviour of the hemi-egg shells are also discussed. Finally, the experimental results are compared to the buckling predictions. A good correlation is observed between numerical results and experiments.

The present work investigates the elasto-visco-plastic buckling of thick plate structures. Methods to estimate the buckling of thin elasto-visco-plastic shells and plates are proposed in literature. To the knowledge of the authors, only few works present experimental results, and none treat the experimental elasto-visco-plastic buckling of thick plate. Thick rectangular plates are chosen as a structure of interest to study elasto-visco-plastic buckling. A modelling/experimental approach is followed to solve such problem. Buckling experiments at room temperature on thick elasto-visco-plastic plates subjected to compressive load are performed. 3D digital image correlation (3D-DIC) is used to measure displacement fields on plate surface during buckling experiments. The experiments are also modelled through a finite element model. Bodner’s approach is coupled to Hencky’s deformation theory to predict buckling of elasto-visco-plastic plates. Bifurcation analysis are performed to estimate buckling critical stresses and strains, and buckling modes. Geometrical and loading imperfections are also discussed. A good correlation is observed between numerical results and experiments. The limitation of Bodner’s approach is also discussed.

The numerical simulation of ballistic multi-hit impact on ceramic/composite armors is very challenging. The damage introduced by the previous hit affects the performance of the armor. In composite backings the damage is often more diffused than for metallic backings. Moreover, different sources of damage can intervene within the composite material. The present work proposes a mesoscopic scale approach to assess these issues. The 2D woven material is modelled with beams elements embedded in volume elements. Each component has its own material constitutive law and its damaging law. This approach allows to better model the damaging of the material, but also to better identify the material parameters from a set of basic experiments.

In the international realm, inter-organizational networking is perceived as a highly relevant instrument in social policy that enables welfare organizations to deal with "wicked issues." In this article, we discuss the central empirical findings acquired from a recent qualitative research project that focuses on inter-organizational networks that were formed at the local level to deal with the wicked issue of child poverty as a complex and multidimensional social problem. We explore how the network discussions about normative value orientations in four inter-organizational networks evolve, and identify three central fields of tension that illustrate the complexity for local welfare actors in and across networks to create network strategies in dealing with child poverty: (a) selective versus universal provision, (b) conditional versus unconditional strategies, and (c) instrumental versus lifeworld-oriented approaches. Our findings show that networks can function as valuable forums for collective debate and reflection, since different approaches and perspectives to tackle the problem of child poverty can be confronted with each other. Creating such a forum has the potential to challenge dominant conceptualizations and undesirable assumptions of complex social problems that are present in welfare practices and policies.

Honey polyphenols have been studied with the objective of relating honeys to their floral sources. Initially synthesized by plant, these polyphenols can be found in the plant's nectar, which are collected by bees, which convert the nectar into honey. Consequently, polyphenols constitute minor components of honey. The development of a solid-phase extraction method for honey polyphenols is presented in this study. The technique employs Amberlite XAD-2 adsorbent and was tested on monofloral honeys from six different plants: acacia, chestnut, eucalyptus, thyme, sunflower, and wild carrot. Analyses were performed using high-performance liquid chromatography coupled with UV detection and mass spectrometry. Several phenolic acids and flavonoids were identified: caffeic and p-coumaric acids, quercetin, kaempferol, naringenin, chrysin, and pinocembrin. Generally, the quantity of a given polyphenol in the honey was around 0.2 mg/100 g of honey, except for chestnut honey, which contained around 3.0 mg of p-coumaric acid/100 g of honey. Analyses highlighted significant formation of cis isomers for phenolic acids during the extraction despite protection from light.

Objectives. We investigated endocrine correlates of the hemodynamic changes induced by carbon dioxide pneumoperitoneum (PNO). We then studied whether clonidine might modulate the hemodynamic changes induced by PNO by reducing release of catecholamines and vasopressin.Background. Both mechanical and neurohumoral factors contribute to the hemodynamic changes induced by carbon dioxide PNO. Several mediators have been proposed, but no study has correlated hemodynamic changes with changes in levels of these potential mediators.Methods. We conducted two studies, each including 20 healthy patients scheduled for elective laparoscopic cholecystectomy. In the first study serial measurements of hemodynamics (thermodilution technique) were done during laparoscopy and after exsufflation. Plasma concentrations of cortisol, catecholamines, vasopressin, renin, endothelin and prostaglandins were measured at the same time points. In the second study patients were randomly allocated to receive 8 μg/kg clonidine infused over 1 h or placebo before PNO. Hemodynamics and plasma levels of cortisol, catecholamines and vasopressin were measured during PNO and after exsufflation.Results. Peritoneal insufflation resulted in a significant reduction of cardiac output (18 ± 4%) and increases in mean arterial pressure (39 ± 8%) and systemic (70 ± 12%) and pulmonary (98 ± 18%) vascular resistances. Laparoscopy resulted in progressive and significant increases in plasma concentrations of cortisol, epinephrine, norepinephrine and renin. Vasopressin plasma concentrations markedly increased immediately after the beginning of PNO (before PNO 6 ± 4 pg/ml; during PNO 129 ± 42 pg/ml; p < 0.05). The profile of vasopressin release paralleled the time course of changes in systemic vascular resistance. Prostaglandins and endothelin did not change significantly. Clonidine significantly reduced mean arterial pressure, heart rate and the increase in systemic vascular resistance. Clonidine also significantly reduced catecholamine concentrations but did not alter vasopressin and cortisol plasma concentrations.Conclusions. Vasopressin and catecholamines probably mediate the increase in systemic vascular resistance observed during PNO. Clonidine before PNO reduces catecholamine release and attenuates hemodynamic changes during laparoscopy.

The small bowel (SB), an organ replete with lymphocytes, may provoke graft-versus-host disease (GVHD) after transplantation (Tx). Since tumor necrosis factor (TNF) has been suspected of mediating the tissue lesions of GVHD, we sought to determine whether TNF could be detected in the serum of rats undergoing GVHD after SBTx or lymphocyte transfer. For this purpose, post-operative serum TNF activity was determined in Lewis x Brown after undergoing transplantation of an entire (group 1; n=8) or a segmental (group 2; n=4) Lew SB, or after i. p. injection with lethal doses (500×106) of Lew lymphocytes (group 3; n=3). Control LBNF1 received i.p. small doses (50×106) of Lew lymphocytes (group 4; n=4). Serum TNF activity was assessed using the WEHI bioassay. In rats with acute and lethal GVHD after entire SBTx (group 1) or injection with large doses of lymphocytes (group 3), TNF activity gradually increased and reached high levels by the time the rats were agonal. In segmental SBTx rats (group 2), GVHD was less severe than in entire SBTx rats. Similarly, the increase in TNF activity was less intense and only transient since it had returned to control levels by the time the rats had completely recovered from GVHD. In control rats primed with small doses of lymphocytes (group 4), GVHD did not occur and no increase in TNF activity was detected. We conclude that: (1) GVHD after SBTx or lymphocyte transfer is associated with the appearance of TNF in the serum and (2) the intensity and the reversibility of this phenomenon correlate with clinical severity and lethality of GVHD. These data strongly suggest that TNF is involved in the pathogenesis of GVHD.

Only a few cases of combined liver and heart transplantation have been reported in the literature, and no standard surgical procedure has yet been established. We report the successful transplantation of both liver and heart in a 28-year-old patient suffering from homozygous beta-thalassemia. We used Belghiti's technique of inferior vena caval flow preservation for liver transplantation, which avoids inferior vena cava occlusion by a side-to-side caval anastomosis. Applied to combined liver and heart transplantation, preservation of caval flow during liver transplantation may allow early discontinuation of cardiopulmonary bypass and, thus, minimize the general consequences of prolonged bypass.