Homogeneous deposition of particles by absorption on hydrogels

When a drop containing colloidal particles evaporates on a surface, a circular stain made of these particles is often observed due to an internal flow toward the contact line. To hinder this effect, several approaches have been proposed such as flow modification by addition of surfactants or control of the interactions between the particles. All of these strategies involve the liquid phase while maintaining the drying process. However, substitution of evaporation by absorption into the substrate of the solvent has been investigated less. Here, we show that a droplet containing colloidal particles deposited on swelling hydrogels can lead to a nearly uniform coating. We report experiments and theory to explore the relation between the gel swelling, uniformity of deposition and the adsorption dynamics of the particles at the substrate. Our findings suggest that draining the solvent by absorption provides a robust route to homogeneous coatings

Diffusiophoretic manipulation of particles in a drop deposited on a hydrogel

We report an experimental study on the manipulation of colloidal particles in a drop sitting on a hydrogel. The manipulation is achieved by diffusiophoresis, which describes a directed motion of particles induced by solute gradients. By letting the solute concentrations for the drop and the hydrogel be different, we control the motion of particles in a stable suspension, which is otherwise difficult to achieve. We show that diffusiophoresis can cause the particles to move either toward or away from the liquid-air interface depending on the direction of the solute gradient and the surface charge of the particles. We measure the particle adsorption experimentally and rationalize the results with a one-dimensional numerical model. We show that diffusiophoretic motion is significant at the lengthscale of a drop deposited on a hydrogel, which suggests a simple method for the deposition of particles on hydrogels

Haptic Rendering of Interacting Dynamic Deformable Objects Simulated in Real-Time at Different Frequencies

International audienceThe dynamic response of deformable bodies varies significantly in dependence on mechanical properties of the objects: while the dynamics of a stiff and light object (e. g. wire or needle) involves high-frequency phenomena such as vibrations, much lower frequencies are sufficient for capturing dynamic response of an object composed of a soft tissue. Yet, when simulating mechanical interactions between soft and stiff deformable models, a single time-step is usually employed to compute the time integration of dynamics of both objects. However, this can be a serious issue when haptic rendering of complex scenes composed of various bodies is considered. In this paper, we present a novel method allowing for dynamic simulation of a scene composed of colliding objects modelled at different frequencies: typically, the dynamics of soft objects are calculated at frequency about 50 Hz, while the dynamics of stiff object is modeled at 1 kHz, being directly connected to the computation of haptic force feedback. The collision response is performed at both low and high frequencies employing data structures which describe the actual constraints and are shared between the high and low frequency loops. During the simulation, the realistic behaviour of the objects according to the mechanical principles (such as non-interpenetration and action-reaction principle) is guaranteed. Examples showing the scenes involving different bodies in interaction are given, demonstrating the benefits of the proposed method

Reply to Karpitschka et al.: The Neumann force balance does not hold in dynamical elastowetting

International audienceIn their letter [1], Karpitschka et al. discuss our claim that the predictions of our theoretical description for the spreading of a droplet on a soft solid layer based on a global-dissipation approach [2] differ from the outcomes of Karpitschka et al.'s model based on a local-force-balance analysis [3]. In particular, Karpitschka et al. claim that our conclusion results from a misstep in our calculation. We explain here the motivations behind our approach and why we think that their model is different from ours, the latter being the only one able to reproduce our extensive set of experimental data. Let us state first that we agree with Karpitschka et al. that "models based on energy dissipation or on force balance" should be "equivalent". However, contrary to their claim, the dissipation power P visc due to viscoelastic stresses cannot be transformed into a contour integral in general. In particular, care must be taken when fields such as strains or stresses present jumps in their value. Such a jump occurs in the elastowetting problem, as the sign of the first derivative of the strain field jumps from negative to positive in the vicinity of the contact line. The solid must be divided in two regions A and B separated by a surface Γ that encompasses the contact line and that is normal to the flat elastomer surface. The dissipation P visc in this system reads: P visc = A B σ ij˙ ij d 2 s = ∂A ∂B/Γ σ ij n jui d + Γ [σ ijui ]n j d (1) where the symbol [f ] denotes the jump of f across Γ. The last term in the equation above does not vanish for arbitrary thickness and rheology. Thus, we conclude that the simple form of the divergence theorem on which Eq. 1 in ref. [1] is based cannot be used here. As a final note, we would like to indicate that current work in our group shows that configurational forces contribute to global dissipation besides Newtonian forces. In our paper [2], instead of calculating the full dissipation, we choose a simpler, approximated route. Indeed, we do not enforce Neumann's force balance at the contact line and we hypothesize that dissipation can be represented by a single term (∼ A B σ zx˙ zx d 2 s). Thus, our model is not equivalent to Karpitschka et al.'s. The remaining dissipative term is then calculated under some approximations, as an effective representation of the full dissipation. The resulting formula provides an excellent fit to the experimental data for the dependence of the dynamic contact angle on the thickness of the elastomer layer, indicating that the approximations underlying our description are reasonable. In contrast, Karpitschka et al.'s model does not capture our data. In other words, our results do not support the hypothesis that the Neumann force balance holds at the tip of a moving contact line, as stated in our paper. We note that our model is only one step among many others that remain to build a thorough and sound description of the dynamics of elastowetting. We agree with Karpitschka et al. that work remains to be done to explain the vast amount of observations that has been reported in the literature on the topic of elastowetting

Impact of RSV test positivity, patient characteristics, and treatment characteristics on the cost of hospitalization for acute bronchiolitis in a French university medical center (2010–2015)

BackgroundIn young children, respiratory syncytial virus (RSV)-related bronchiolitis is typically more severe than other respiratory tract infections, with a greater need for oxygen therapy and respiratory support. Few studies have compared the cost of hospitalization with regard to virological status. The objective of this study was to compare the costs of hospitalization for RSV-positive vs. RSV-negative bronchiolitis in a French university medical center between 2010 and 2015.MethodsThe cost models were compared using conventional goodness-of-fit criteria. Covariates included the characteristics of the patients, pre-existing respiratory and non-respiratory comorbidities, superinfections, medical care provided, and the length of stay.ResultsRSV was detected in 679 (58.3%) of the 1,164 hospital stays by children under 2 years with virological data. Oxygen therapy and respiratory support were twice as frequent for the RSV-positive cases. The median hospitalization cost was estimated at €3,248.4 (interquartile range: €2,572.1). The cost distribution was positively skewed with a variation coefficient (CV = standard deviation/mean) greater than one (mean = €4,212.9, standard deviation = €5,047, CV = 1.2). In univariate analyses, there was no significant cost difference between the RSV-positive and RSV-negative cases. In the best multivariate model, the significant positive effect of RSV positivity on cost waned after the introduction of medical care variables and the length of stay. The results were sensitive to the specification of the model.ConclusionsIt was impossible to firmly conclude that hospitalization costs were higher for the RSV-positive cases

Trials

BACKGROUND: Postoperative upper gastrointestinal fistula (PUGIF) is a devastating complication, leading to high mortality (reaching up to 80%), increased length of hospital stay, reduced health-related quality of life and increased health costs. Nutritional support is a key component of therapy in such cases, which is related to the high prevalence of malnutrition. In the prophylactic setting, enteral nutrition (EN) is associated with a shorter hospital stay, a lower incidence of severe infectious complications, lower severity of complications and decreased cost compared to total parenteral nutrition (TPN) following major upper gastrointestinal (GI) surgery. There is little evidence available for the curative setting after fistula occurrence. We hypothesize that EN increases the 30-day fistula closure rate in PUGIF, allowing better health-related quality of life without increasing the morbidity or mortality. METHODS/DESIGN: The NUTRILEAK trial is a multicenter, randomized, parallel-group, open-label phase III trial to assess the efficacy of EN (the experimental group) compared with TPN (the control group) in patients with PUGIF. The primary objective of the study is to compare EN versus TPN in the treatment of PUGIF (after esophagogastric resection including bariatric surgery, duodenojejunal resection or pancreatic resection with digestive tract violation) in terms of the 30-day fistula closure rate. Secondary objectives are to evaluate the 6-month postrandomization fistula closure rate, time of first fistula closure (in days), the medical- and surgical treatment-related complication rate at 6 months after randomization, the fistula-related complication rate at 6 months after randomization, the type and severity of early (30 days after randomization) and late fistula-related complications (over 30 days after randomization), 30-day and 6-month postrandomization mortality rate, nutritional status at day 30, day 60, day 90 and day 180 postrandomization, the mean length of hospital stay, the patient's health-related quality of life (by self-assessment questionnaire), oral feeding time and direct costs of treatment. A total of 321 patients will be enrolled. DISCUSSION: The two nutritional supports are already used in daily practice, but most surgeons are reluctant to use the enteral route in case of PUGIF. This study will be the first randomized trial testing the role of EN versus TPN in PUGIF. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03742752. Registered on 14 November 2018.This research program is funded by the French Ministry of Health through Programme Hospitalier de Recherche Clinique 2016

Nouveaux modes de prise en charge des carrières « déliées » : une innovation institutionnelle ?

Colloque - La notion de « carrières déliées » a souvent été associée à un pilotage de la trajectoire professionnelle par l’individu lui-même. Divers dispositifs d’intermédiation ont pourtant vu le jour pour aider à la prise en charge de ces nouvelles formes de carrière. A l’aide d’une étude de cas dans le secteur artistique belge, nous approfondissons ici la capacité d’un dispositif militant, explicitement tourné vers une transformation du marché du travail, à s’inscrire dans un processus d’innovation institutionnelle. Nous montrons que cette innovation consiste en un déplacement de l’objet même de la prise en charge, passant désormais de la relation d’emploi à la transition professionnelle, probablement annonciatrice de mutations plus profondes sur le marché du travail."ARC-Understanding flexicurity

Etude rétrospective, multicentrique de la traumatologie dans la pratique du kung fu whushu

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

The contribution of the theory of the actor-network in the professionalization of the HRM in an institution of care

peer reviewedCet article présente une méthodologie d’intervention, basée sur les principes de la sociologie de la traduction (ou sociologie de l’acteur-réseau), qui a pour but de développer une politique de GRH en milieu hospitalier ainsi que de maîtriser les risques liés à la mise en œuvre du changement. Partant de la volonté d’un Centre Hospitalier Universitaire créé il y a une trentaine d’années d’agir sur sa politique de ressources humaines et de revoir en profondeur son fonctionnement en matière de gestion des compétences, la question du choix de la méthode de travail à adopter s’est d’emblée posé. Comment initier une démarche de professionnalisation de la GRH dans une institution de soins essentiellement centrée sur l’administration du personnel ? Nous entendons faire le point sur une expérience pilote toujours en cours, sur l’approche polyphonique du changement utilisée, ses difficultés et ses conditions de succès, ainsi que sa capacité à contribuer au développement d’une gestion des ressources humaines intégrée au sein d’une institution hospitalière. Enfin, nous évoquerons plusieurs difficultés susceptibles d’être rencontrées dans ce contexte, comme l’ « effet groupe-pilote », l’influence des médecins ou la lassitude des acteurs face à la durée d’un tel projet.This paper presents an intervention methodology, based on actor-network theory principles, which aims at developing an HR policy in the health sector, and manage the risks linked to the implementation of the organization changes. Starting from the strategy of the University Hospital, created about thirty years ago, to review its HR management and to change significantly the way talent and skills are managed, the choice of the right methodology was immediately a key concern. How can we raise HR management to a professional level, in an organization which was until then focused on payroll management only? In this paper, we analyze a pilot, which is still running, on the polyphonic change management approach, its challenges and success factors, and its ability to contribute to the development of a fully integrated HR management in a hospital. Finally, we will take a look at several issues that can appear in such a context, like the ‘pilot-group effect’, the doctor’s influence or the motivation decrease of the people involved in such a lengthy project

L’apport de la théorie de l’acteur-réseau à la professionnalisation de la GRH dans une institution de soins.

Nous entendons par cette communication faire le point sur une expérience pilote en cours, sur la méthodologie mise en place, ses difficultés et ses conditions de succès, ainsi que sur sa capacité à contribuer au développement d’une gestion des ressources humaines intégrée au sein d’une institution hospitalière. Plusieurs points d’attention méritent néanmoins d’être soulignés, comme l’ « effet groupe-pilote », l’influence des médecins ou la lassitude des acteurs face à la durée d’un tel projet. Ils constituent autant de facteurs de risque susceptibles d’affecter le bon déroulement de la démarche entamée