A multilayer Saint-Venant system with mass exchanges for Shallow Water flows. Derivation and numerical validation

The standard multilayer Saint-Venant system consists in introducing fluid layers that are advected by the interfacial velocities. As a consequence there is no mass exchanges between these layers and each layer is described by its height and its average velocity. Here we introduce another multilayer system with mass exchanges between the neighborhing layers where the unknowns are a total height of water and an average velocity per layer. We derive it from Navier-Stokes system with an hydrostatic pressure and prove energy and hyperbolicity properties of the model. We also give a kinetic interpretation leading to effective numerical schemes with positivity and energy properties. Numerical tests show the versatility of the approach and its ability to compute recirculation cases with wind forcing.Comment: Submitted to M2A

Random effects compound Poisson model to represent data with extra zeros

This paper describes a compound Poisson-based random effects structure for modeling zero-inflated data. Data with large proportion of zeros are found in many fields of applied statistics, for example in ecology when trying to model and predict species counts (discrete data) or abundance distributions (continuous data). Standard methods for modeling such data include mixture and two-part conditional models. Conversely to these methods, the stochastic models proposed here behave coherently with regards to a change of scale, since they mimic the harvesting of a marked Poisson process in the modeling steps. Random effects are used to account for inhomogeneity. In this paper, model design and inference both rely on conditional thinking to understand the links between various layers of quantities : parameters, latent variables including random effects and zero-inflated observations. The potential of these parsimonious hierarchical models for zero-inflated data is exemplified using two marine macroinvertebrate abundance datasets from a large scale scientific bottom-trawl survey. The EM algorithm with a Monte Carlo step based on importance sampling is checked for this model structure on a simulated dataset : it proves to work well for parameter estimation but parameter values matter when re-assessing the actual coverage level of the confidence regions far from the asymptotic conditions.Comment: 4

Data Assimilation for hyperbolic conservation laws. A Luenberger observer approach based on a kinetic description

Developing robust data assimilation methods for hyperbolic conservation laws is a challenging subject. Those PDEs indeed show no dissipation effects and the input of additional information in the model equations may introduce errors that propagate and create shocks. We propose a new approach based on the kinetic description of the conservation law. A kinetic equation is a first order partial differential equation in which the advection velocity is a free variable. In certain cases, it is possible to prove that the nonlinear conservation law is equivalent to a linear kinetic equation. Hence, data assimilation is carried out at the kinetic level, using a Luenberger observer also known as the nudging strategy in data assimilation. Assimilation then resumes to the handling of a BGK type equation. The advantage of this framework is that we deal with a single "linear" equation instead of a nonlinear system and it is easy to recover the macroscopic variables. The study is divided into several steps and essentially based on functional analysis techniques. First we prove the convergence of the model towards the data in case of complete observations in space and time. Second, we analyze the case of partial and noisy observations. To conclude, we validate our method with numerical results on Burgers equation and emphasize the advantages of this method with the more complex Saint-Venant system

The Effect of Mindfulness Meditation on Emotional Distress in Adult Cancer Patients

Significant advances in cancer treatments have been made over recent decades resulting in state of the art screening and treatment options that have contributed to higher rates of cancer survivorship. However, despite the increase in cancer survivors, a cancer diagnosis continues to be associated with a significant amount of emotional distress and psychological issues that further add to the burden of the disease. The Institute of Medicine (2008), recognizes that a failure to adequately address this problem results in needless suffering and may obstruct quality of care; thereby, leading to a potentially negative impact on the disease course. Among the many interventions available to support patients who are experiencing high levels of emotional burden, mindfulness meditation (MM) has been identified as an effective option. MM is a form of meditation where an individual focuses on moment-to-moment experiences in a nonjudgmental way (Poulin, Mackenzie, Soloway, & Karayolas, 2008). This evidence based practice (EBP) project examined the effects of a six-week MM program on the emotional distress scores of cancer patients living in Eastern Long Island, New York. The MM intervention was modeled after the Mindfulness-Based Stress Reduction (MBSR) program developed by John Kabat-Zinn. Orem’s theory of self-care and the Stetler model guided the EBP project. The Brief Symptoms Inventory-18 (BSI-18) and the Distress Thermometer (DT) measured changes in emotional distress. Descriptive statistics and a non-parametric test, the Wilcoxon signed rank test, were used to compare pre and post scores of the BSI-18 and the DT. Post intervention scores on all three of the BSI-18 subscales demonstrated statistically significant reductions in somatization (p = .30), depression (p = .010), and anxiety (p = .006). Post intervention scores on global severity (p = .013), which represents the participant’s overall level of distress also demonstrated statistically significant reductions. Post interventions scores from the DT (p = .121) did not however demonstrate a statistically significant reduction in distress. Findings suggest that MM can be effective in managing emotional distress in oncology patients, however additional studies using heterogeneous cancer patients and larger samples are needed

The Impact of Interface Quality on Trust in Web Retailers

Web retailing is expected to grow at aggressive rates in future years. One of the most important factors that is slowing down this growth is the lack of trust of potential customers. So, as transactions through the internet develop and mature, success will largely be dependent on gaining and0501ntaining this trust. It has been suggested that the quality of the user interface of the Web site is a determinant of the initial establishment of trust. In this article, we describe a study where 66 subjects were asked to perform some predefined book purchasing task in a series of sites with varying interface quality. We found a strong relationship between interface quality and trust. We also found some components of user interface quality to be more important than others and discuss the implications for Web site design. Le manque de confiance constitue une des barrières les plus importantes à l'adoption et au développement du commerce électronique. Centré sur le commerce électronique de détail, ce travail présente un modèle permettant d'analyser le développement de la confiance du consommateur en fonction des caractéristiques de ce dernier - sa propension - et de la perception qu'il a de certaines caractéristiques du commerçant, soit l'intégrité, l'habilité et la bienveillance de ce dernier. L'utilisabilité de l'interface graphique a été retenue comme étant le facteur-clé en ce qui concerne la perception de ces caractéristiques. Le rôle de chacune des dimensions composant l'utilisabilité a donc été étudié et mis en évidence relativement à la confiance développée par le consommateur.User interface, laboratory experiment, trust, usability, electronic retailing, web design, Interface utilisateur, expérimentation en laboratoire, confiance, b2c, commerce électronique (détail), design de site web

Effect of surface preparation on the corrosion of austenitic stainless steel 304L in high temperature steam and simulated PWR primary water

The corrosion behavior of 304L grade stainless steel (SS) in high-temperature steam and in a simulated Pressurized Water Reactor (PWR) is studied. The goal was to characterize the nature of the oxide coating generated during 500 h exposure of samples in a 400 °C steam (200 bar) or a 340 °C simulated PWR. Accelerating the effect of the steam environment as well as the influence of surface preparation have been studied. Two initial sample surfaces were used: mechanical polishing and finishing grinding. Oxide coatings were investigated using TEM imaging coupled with EELS spectroscopy and R – SIMS (Secondary Ion Mass Spectroscopy)

Le transfert des connaissances pour prévenir les chutes chez des personnes âgées en centre hospitalier cardiovasculaire aigu

Rapport de stage présenté à la Faculté des sciences infirmières en vue de l'obtention du grade de Maître ès sciences (M.Sc.) option expertise-conseil en soins infirmiersLe stage consistait à déployer une approche de transfert des connaissances pour prévenir les chutes chez des personnes âgées en centre hospitalier cardiovasculaire aigu. Une combinaison de stratégies s’articulant autour d’ateliers interactifs a favorisé le transfert auprès des intervenants d’une unité ciblée. Le projet a été encadré par le cadre conceptuel Promoting Action on Research Implementation in Health Services (PARIHS) et fut planifiée selon la Marche à suivre pour implanter des lignes directrices pour la pratique clinique proposée par l’Association des infirmières et infirmiers autorisés de l’Ontario. Pour sélectionner les connaissances à implanter, un outil d’évaluation du risque de chute a été actualisé et un aide-mémoire sur la prévention des chutes a été développé. Les parties prenantes ont été impliquées précocement et tout au long du projet. Les stratégies de mise en place ont comporté de brefs ateliers de remue-méninges, une campagne de promotion et un suivi de pérennité. Finalement, l’évaluation du projet s’est tenue 12 semaines après les ateliers. Vingt-quatre ateliers de 45 minutes furent animés sur les trois quarts de travail et 93 % des divers intervenants actifs de l’unité ciblée y ont participé. Un niveau de sensibilisation accru fut démontré par l’évaluation du projet. Regrouper différents intervenants pour une même activité nous a semblé propice à leur cohésion et leur communication. Les commentaires reçus soulignent leur appréciation d’avoir été consultés précocement et impliqués dans le processus d’implantation. Proposer un horaire souple et privilégier un partage bilatéral des connaissances par de courtes discussions interactives ont aussi été appréciés.The purpose of this master's degree project was to develop and implement a knowledge transfer approach in the prevention of falls among an elderly population in an acute cardiovascular setting. Thus, a combination of strategies based on interactive workshops facilitated the knowledge transfer with the healthcare professionals of a targeted unit. To select the knowledge to be implanted, an evaluation tool was updated and an intervention tool was developed. The participants were involved early and throughout the project. Analysis of the participants' environment was outlined by the Promoting Action on Research Implementation in Health Services (PARIHS) conceptual framework. The strategies of implementation consisted mainly of a promotional campaign, brief awareness and brainstorming workshops, as well as a series of follow-ups. Finally, an evaluation of the project was held 12 weeks after completion of the workshops. The gathering resources stage was facilitated by the managers' collaboration. Twenty-four workshops were held during day, evening and night shifts. Consequently, 93 % of the various active participants in the targeted unit took part in the workshops. A greater level of awareness was noted among participants following the evaluation of the project. To group together various participants for the same activity seemed convenient to us for many reasons, including group cohesion and communication. Our observations and the various comments received underline the participants' appreciation in having been consulted and involved early on in the implementation process. Other positives noted were the flexible schedule of activities and the bilateral knowledge sharing within interactive discussions.Groupe de recherche interuniversitaire en interventions en sciences infirmières du Québec (GRIISIQ); Fondation de l’Institut de cardiologie de Montréal (ICM); direction des soins infirmiers de l’Institut de cardiologie de Montréal (ICM

Nitrogen leaching from organic agriculture and conventinal crop rotations

The goal of our study is to investigate nitrogen leaching from organic agriculture, taking into account a complete organic rotation (6-9 years) and to compare the results with leaching from conventional systems. There are long time series on sub-root crop concentrations in conventional agriculture in the Seine Basin. These scored an average of 25 ± 4 mg N-NO3.l-1 (standard for drinking water is 11 mg N-NO3.l-1) in different types of soil, crops and climatic conditions. However, no data still exists for organic farming (OF) in this area. In 2012-2013, a total of eight practices of arable crops have been equipped with suction cups for all their rotations (5 in OF and 3 in CF), in three pedoclimatic situations, in order to determine concentrations and fluxes of nitrogen leached. In the conditions of the first step of our study, the average of sub-root concentrations in the organic rotations was 11 ± 6 mgN-NO3.l-1 (N=35) against 26 ± 9 mgN-NO3.l-1 (N=8) for the conventional ones. Organic farming in the north of France could therefore reduce by 60% the nitrogen leaching potential compared to conventional practices widely spread in the Ile-de-France Region and the Seine Basin