Mathematical modeling and numerical simulation of a bioreactor landfill using Feel++

In this paper, we propose a mathematical model to describe the functioning of a bioreactor landfill, that is a waste management facility in which biodegradable waste is used to generate methane. The simulation of a bioreactor landfill is a very complex multiphysics problem in which bacteria catalyze a chemical reaction that starting from organic carbon leads to the production of methane, carbon dioxide and water. The resulting model features a heat equation coupled with a non-linear reaction equation describing the chemical phenomena under analysis and several advection and advection-diffusion equations modeling multiphase flows inside a porous environment representing the biodegradable waste. A framework for the approximation of the model is implemented using Feel++, a C++ open-source library to solve Partial Differential Equations. Some heuristic considerations on the quantitative values of the parameters in the model are discussed and preliminary numerical simulations are presented

Collision detection between robots moving along specified trajectories

An algorithm to detect collisions between robots moving along given trajectories is presented. The method is a combination of the adaptive dynamic collision checking developed by Schwarzer et al. and Lin and Canny's algorithm, which computes efficiently the distance between two polyhedra. The resulting algorithm is part of a global model that computes the optimal task assignment, sequencing and kinodynamic motion planning in a robotic work-cell

Collision detection between robots moving along specified trajectories

An algorithm to detect collisions between robots moving along given trajectories is presented. The method is a combination of the adaptive dynamic collision checking developed by Schwarzer et al. and Lin and Cannys algorithm, which computes efficiently the distance between two polyhedra. The resulting algorithm is part of a global model that computes the optimal task assignment, sequencing and kinodynamic motion planning in a robotic work-cell

La Generative Fotografie

L’auteur tient à remercier Michel Poivert. Du 21 janvier au 18 février 1968 a lieu à la Kunsthaus de Bielefeld (RFA) une exposition intitulée “Generative Fotografie” où sont exposés les travaux de quatre jeunes photographes – trois allemands, Gottfried Jäger, Hein Gravenhorst, Kilian Breier et un belge, Pierre Cordier, ces deux derniers ayant accompli une partie de leur formation à Sarrebruck auprès du chef de file de la Subjektive Fotografie, Otto Steinert. Ces travaux photographiques sont p..

De l’empire au marché

La croissance rapide de la République fédérale d’Allemagne a souvent été imputée à la seule relance du système économique offrant jusqu’au début des années 1960 l’image d’un pays excessivement prosaïque dans lequel l’art – majoritairement abstrait – est détaché des considérations politiques et structurelles du nouvel état. Pourtant, dans le domaine photographique, la naissance de la Photokina en 1950 à Cologne atteste du lien étroit qui se crée dans les années de la reconstruction entre l’industrie et la pratique photographique. Après 1945, un champ photographique unifié naît en Allemagne de l’Ouest, fruit de la volonté conjointe des entreprises nationales et des utilisateurs tant professionnels qu’amateurs. L’entreprise Agfa joue un rôle majeur dans ce nouvel agencement. Le cartel IG Farben rompu par les Alliés, Agfa est obligée à une autonomie qui, face à la concurrence étrangère, fragilise sa position dominante en Allemagne, déjà sapée par la partition du pays et la destruction des usines. L’entreprise devient un des fers de lance de la modification structurelle de l’économie allemande du secteur secondaire vers le secteur tertiaire. Les regroupements d’entreprises qu’elle initie après-guerre se basent, au contraire de l’IG Farben, sur le secteur marchand qu’elle vise. Cette évolution implique une fidélisation de la clientèle qui passe par un soutien aux acteurs – associations, écoles –, déjà présents dans le domaine, et la création de nouvelles structures défendant les enjeux modernes du médium telle la Photokina en 1950. Ce système de valorisation de la photographie reposant sur une alliance entre économie et création crée une identité propre au médium et forme le socle de la vigueur et du retentissement de la photographie allemande à l’époque.The rapid growth of the Federal Republic of Germany has often been attributed exclusively to the revival of its economy. The result has been to project the image of a country that, until the early 1960s, was overly prosaic and where art, predominantly abstract, was detached from the new state’s political and structural concerns. Yet in the area of photography, the birth of Photokina in Cologne in 1950 attests to the emergence of a close link between industry and photographic practice during the period of reconstruction. After 1945, a unified photography sector emerged in West Germany as a result of the concerted efforts of domestic firms and professional as well as amateur photographers. The Agfa corporation played a central role in helping to bring this about. When the IG Farben cartel was broken up by the Allies, Agfa was forced to become autonomous; together with pressure from foreign competition, this weakened its dominant position in West Germany, which had already been undermined by the country’s division and the destruction of its factories. Agfa became one of the spearheads for the structural modification of the German economy, from a sector of industry-based cartels, to a sector based on service-oriented consortiums. Unlike IG Farben, the industrial groupings that Agfa initiated after the war were based on the market it wished to reach. This development entailed the cultivation of customer loyalty, which involved supporting those actors who were already present in the field – associations and schools – as well as creating new structures and organizations such as Photokina in 1950 in an effort to advance the modern aspects of the medium. Rooted in an alliance between the industry and the practice of photography, this system for promoting photography created a distinctive identity for the medium and served as the basis for the dynamism and high profile of the German photography of the time

Pour ne plus être le miroir de l’Allemagne

Dans les premières années de l’après-guerre, le champ de la photographie se construit dans une accointance directe au destin de l’Allemagne. De l’occupation où l’utilisation du médium est avant tout politique au développement économique des années cinquante, tout dans le domaine photographique semble en faire le miroir à petite échelle de la construction de la République fédérale. Pourtant, à partir de 1955, la photographie vient à critiquer, voire dénigrer, une bonne part des projets qu’elle avait jusque-là défendus, démontrant l’autonomie progressive que n’aura de cesse de s’octroyer le médium. La réflexion menée dans cet article s’appuie sur les composantes économiques et théoriques du champ photographique en regard des productions artistiques, sans faire l’impasse sur les livres illustrés (Chargesheimer, Hermann Claasen, Walter Dick) et les expositions importantes de l’époque dont celles de la photokina de Cologne.In den ersten Nachkriegsjahren bildet sich die Fotografie in einem direkten Bezug zum Werdegang Deutschlands heraus. Der gesamte Bereich der Fotografie macht aus dem Medium von der Besatzungszeit an, wo die Fotografie vor allem politisch genutzt wird, über die ökonomische Entwicklung bis hin zur Blüte Anfang der 50er Jahre, eine Spiegelung kleineren Maßstabs des deutschen Wiederaufbaus.Unsere Überlegungen beziehen sich auf den Bereich im Zusammenhang mit den ökonomischen und theoretischen Komponenten im Blick auf die künstlerischen Produktionen. Wir untersuchen anhand von Bildbänden (Chargesheimer, Hermann Claasen, Walter Dick), bedeutender Ausstellungen jener Zeit – darunter die photokina in Köln.In the first years after World War II, the photographic field follows the West German destiny. During the occupation, the utilization of this medium is first a political one. Until the economic development, the photographic field seems to be the perfect reflection of the building of the GDR. Though, from 1955, photography begins to critic an important part of what it was fighting for. The medium becomes more independant. This articles try to understand this changement by examinate the economical and theorical components of the photographic field and the illustrate books (Chargesheimer, Hermann Claasen, Walter Dick) and the essential exhibitions like the photokina in Cologne

Optimal Transportation for Data Assimilation

International audienceWe present here how 4DVar data assimilation can be performed with the Wasserstein distance. Some results are shown

Optimal transport for data assimilation

National audienceApplying optimal transport to data assimilation can be natural in the case where data are images for example. Indeed, optimal transport theory introduces the so-called Wasserstein distance which can be useful to compare images, and it may be more natural than using classical euclidean distances.The interesting points, as well as the methodology, the technical difficulties and some results of applying optimal transport to data assimilation are presented here

Screening of Bioactive Peptides Using an Embryonic Stem Cell-Based Neurodifferentiation Assay

Differentiation of pluripotent stem cells, PSCs, towards neural lineages has attracted significant attention, given the potential use of such cells for in vitro studies and for regenerative medicine. The present experiments were designed to identify bioactive peptides which direct PSC differentiation towards neural cells. Fifteen peptides were designed based on NCAM, FGFR, and growth factors sequences. The effect of peptides was screened using a mouse embryonic stem cell line expressing luciferase dual reporter construct driven by promoters for neural tubulin and for elongation factor 1. Cell number was estimated by measuring total cellular DNA. We identified five peptides which enhanced activities of both promoters without relevant changes in cell number. We selected the two most potent peptides for further analysis: the NCAM-derived mimetic FGLL and the synthetic NCAM ligand, Plannexin. Both compounds induced phenotypic neuronal differentiation, as evidenced by increased neurite outgrowth. In summary, we used a simple, but sensitive screening approach to identify the neurogenic peptides. These peptides will not only provide new clues concerning pathways of neurogenesis, but they may also be interesting biotechnology tools for in vitro generation of neurons

Invited Review: Decoding the pathophysiological mechanisms that underlie RNA dysregulation in neurodegenerative disorders: a review of the current state of the art

Altered RNA metabolism is a key pathophysiological component causing several neurodegenerative diseases. Genetic mutations causing neurodegeneration occur in coding and noncoding regions of seemingly unrelated genes whose products do not always contribute to the gene expression process. Several pathogenic mechanisms may coexist within a single neuronal cell, including RNA/protein toxic gain-of-function and/or protein loss-of-function. Genetic mutations that cause neurodegenerative disorders disrupt healthy gene expression at diverse levels, from chromatin remodelling, transcription, splicing, through to axonal transport and repeat-associated non-ATG (RAN) translation. We address neurodegeneration in repeat expansion disorders [Huntington's disease, spinocerebellar ataxias, C9ORF72-related amyotrophic lateral sclerosis (ALS)] and in diseases caused by deletions or point mutations (spinal muscular atrophy, most subtypes of familial ALS). Some neurodegenerative disorders exhibit broad dysregulation of gene expression with the synthesis of hundreds to thousands of abnormal messenger RNA (mRNA) molecules. However, the number and identity of aberrant mRNAs that are translated into proteins – and how these lead to neurodegeneration – remain unknown. The field of RNA biology research faces the challenge of identifying pathophysiological events of dysregulated gene expression. In conclusion, we discuss current research limitations and future directions to improve our characterization of pathological mechanisms that trigger disease onset and progression