Permeability Computation on a Representative Volume Element (RVE) of Unidirectional Disordered Fiber Arrays

International audienceAn efficient method to compute the permeability of disordered fibrous arrays is proposed. A stabilized mixed finite element method is used with an immersed domain approach to represent the porous material at its microscopic scale. Therefore, the Stokes equations are solved in the whole domain (including solid part) using a penalization method. The accuracy is controlled by refining the mesh around the fluid-solid interface defined by a level-set function. Using homogenization techniques, the permeability of an RVE is obtained. Furthermore, a new method to generate disordered fibers in function of the porosity, Φ, and other microstructural parameters is proposed and a study of the effect of inter-fiber spacing on K, the permeability tensor, is performed. This task was achieved using parallel computation and over 460 simulations were carried out in two-dimensional RVEs consisting of over 555 fiber

Stabilized Finite Element Methods vs LES modelling for fluid-strucure interaction with anisotropic adaptive meshing

National audienceThis paper presents a stabilised finite element method for the solution of incompressible multiphase flow problems in three dimensions using an immersed volume method with anisotropic adaptive meshing. A recently developed stabilised finite element solver which draws upon features of solving general fluid-structure interactions is presented. The proposed method is developed in the context of the monolithic formulation. Such strategy gives rise to an extra stress tensor in the Navier-Stokes equations coming from the presence of the structure in the fluid. The distinctive feature of the Variational MultiScale approach is not only the decomposition for both the velocity and the pressure fields into coarse/resolved scales and fine/unresolved scales but also the possible efficient enrichment of the extra constraint. This choice of decomposition is shown to be favorable for simulating multiphase flows at high Reynolds number. We assess the behaviour and accuracy of the proposed formulation coupled to the levelset method approximation in the simulation of 2D and 3D time-dependent numerical examples such as : vortex shedding behind an obstacle, conjugate heat transfer inside industrial furnaces and the rigid bodies motion in incompressible flows.See http://hal.archives-ouvertes.fr/docs/00/59/26/96/ANNEX/r_Q1R43125.pd

False lumen embolization as a rescue technique in the setting of acute and chronic dissecting aneurysms as adjunct to thoracic endovascular aortic repair.

Complicated type B aortic dissection (TBAD) is a life-threatening condition requiring surgical intervention. One such complication in the acute or chronic setting is aneurysmal degeneration. The dissected aortic wall is weakened, and the pressures in the false lumen are often high. In the past decade, thoracic endovascular aortic repair (TEVAR) has become the treatment of choice for TBAD. TEVAR can be complicated by lack of false lumen thrombosis, increasing the risk of death. We present three cases of TBAD with patent false lumens after TEVAR that were treated by false lumen coil embolization

Bringing Upstairs Care Downstairs; Integration of Rehabilitation Medicine, Care Management, and the Hospital Elder Life Program (HELP) into an Emergency Department.

Introduction: Services such as physical therapy (PT), occupational therapy (OT), speech-language pathology (SLP), social work (SW), care management, and elder life specialists have long been an established part of care for patients admitted to Maine Medical Center (MMC) but not for patients in the Emergency Department (ED). Methods and Results: Driven in part by changes in Medicare reimbursement models, care management established a presence in the Emergency Department (ED) in 2003 with a focus on care planning and cost avoidance. In recent years PT, OT, SLP, SW, and the Hospital Elder Life Program (HELP) have increased their ED involvement substantially. These services not only support care management decisions but have become an invaluable part of the ED team. The timing, staffing models, and roles of these services in our emergency department are described. Discussion: There was strong leadership support to create these positions in the ED. Increased patient volume hospital wide has required staffing flexibility. Initial concerns for slowing the ED where anecdotally resolved. Other hospitals in our system are interested in this approach. Conclusions: While the value of this work feels self-evident and is already established for admitted patients, descriptive and outcome-oriented studies for ED patients would be enlightening

Impact of Cigarette Smoke Exposure on Innate Immunity: A Caenorhabditis elegans Model

BACKGROUND: Cigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD) and lung cancer. Respiratory bacterial infections have been shown to be involved in the development of COPD along with impaired airway innate immunity. METHODOLOGY/PRINCIPAL FINDINGS: To address the in vivo impact of cigarette smoke (CS) exclusively on host innate defense mechanisms, we took advantage of Caenorhabditis elegans (C. elegans), which has an innate immune system but lacks adaptive immune function. Pseudomonas aeruginosa (PA) clearance from intestines of C. elegans was dampened by CS. Microarray analysis identified 6 candidate genes with a 2-fold or greater reduction after CS exposure, that have a human orthologue, and that may participate in innate immunity. To confirm a role of CS-down-regulated genes in the innate immune response to PA, RNA interference (RNAi) by feeding was carried out in C. elegans to inhibit the gene of interest, followed by PA infection to determine if the gene affected innate immunity. Inhibition of lbp-7, which encodes a lipid binding protein, resulted in increased levels of intestinal PA. Primary human bronchial epithelial cells were shown to express mRNA of human Fatty Acid Binding Protein 5 (FABP-5), the human orthologue of lpb-7. Interestingly, FABP-5 mRNA levels from human smokers with COPD were significantly lower (p = 0.036) than those from smokers without COPD. Furthermore, FABP-5 mRNA levels were up-regulated (7-fold) after bacterial (i.e., Mycoplasma pneumoniae) infection in primary human bronchial epithelial cell culture (air-liquid interface culture). CONCLUSIONS: Our results suggest that the C. elegans model offers a novel in vivo approach to specifically study innate immune deficiencies resulting from exposure to cigarette smoke, and that results from the nematode may provide insight into human airway epithelial cell biology and cigarette smoke exposure

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Monolithic Variational Multiscale Method for Fluid- Structure Interaction with Anisotropic Adaptive Meshing

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A full Eulerian stabilized finite element method for fluid structure interaction

International audienc

Immersed Stress Method for solving Fluid-Structure Interaction with Anisotropic Mesh Adaptation

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Development of new stabilized three-fields finite element method for fluid-structure interaction

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