Science & Mathematics

A two-degree-of-freedom oscillator excited by dry friction is considered. The system consists of two masses connected by a linear spring, one of which is connected to a fixed wall by another spring. The second mass is in contact with a driving belt moving at a constant velocity. Coulomb's friction force acts between the mass and the belt. Periodic orbits including stick phases and slip phases, during which the mass in contact with the belt moves faster than the belt, are found analytically. The stability of these "overshooting" orbits is also investigated.

Table ronde dans le cadre de la journée d'accélération de l'ICCARE-LAB Arts visuels et arts numériques : quels enjeux à partager pour quels changements à impulser ?

Le saotsa (offrande) agir physique devenu agir linguistique Résumé : Cet article en reprenant l'exemple de la délocutivité chez BENVENISTE démontre que la notion a depuis largement débordé sa définition initiale qui se résume en une forme linguistique de dérivation à partir d'une locution. Tout d'abord, à la suite de DUCROT et ANSCOMBRE, la délocutivité se révèle être une performativité – exclue de la définition initiale – Pour sa part, cet article démontre que la véritable délocutivité consiste à convertir un agir physique en agir linguistique comme le fera apparaître l'analyse de la locution « saotsa » ou « offrande »

The present paper summarizes the key findings of a numerical study on the aerodynamic behavior of a generic light aircraft under flow conditions, which are typically associated with spin motions. These conditions include high angles of attack, crosswind and rotational motion. Besides investigating the limits of Reynolds-averaged Navier-Stokes simulations for this type of conditions, the simulations contribute to a better understanding of existing wind-tunnel data. Furthermore, the influence of wind-tunnel related aspects such as scaling effects are investigated. The comparison between the numerical and experimental results generally shows good agreement regarding global force coefficients and separation behavior. The characteristic behavior with regards to crosswind and rotational motion around the longitudinal wind axis is captured well by the computations. Scaling effects are considerable with the maximum vertical force coefficient increasing by up to ∆C Z,max = 0.25 at real flight Reynolds and Mach number compared to wind-tunnel conditions.

Tissue morphogenesis emerges from coordinated cell shape changes driven by actomyosin contractions. Patterns of gene expression regionalize and polarize cell behaviours by controlling actomyosin contractility. Yet how mechanical feedbacks affect tissue morphogenesis is unclear. We report two modes of control over Rho1 and MyosinII activation in the Drosophila endoderm. First, Rho1/MyoII are induced in a primordium via localized transcription of the GPCR ligand Fog. Second, a tissue-scale wave of Rho1/MyoII activation and cell invagination progresses anteriorly. The wave does not require sustained gene transcription, and is not governed by regulated Fog delivery. Instead, MyoII inhibition blocked acute Rho1 activation and propagation, revealing a mechanical feedback driven by MyoII. Last, we identify a cycle of 3D cell deformations whereby MyoII activation and invagination in each row of cells drives adhesion to the vitelline membrane, apical spreading, MyoII activation and invagination in the next row. Thus endoderm morphogenesis emerges from local transcriptional initiation and a mechanically driven wave of cell deformation.

What explains changes in the economic structures, institutions and policies of Advanced Capitalist Democracies (ACDs)? In this article, we suggest that the various answers to this question in the field of Comparative Political Economy (CPE) are essentially linked to two main approaches. The first approach emphasizes the role of electorates and political parties, their transformations, and their competition in shaping the evolution of ACDs. The second approach highlights the primacy of producer groups as the most powerful actors influencing the trajectory of ACDs. This review article introduces the debate between these two approaches and underscores its enduring relevance. It then discusses four recent important contributions that provide renewed perspectives on what remains a structuring cleavage in CPE, with implications for neighbouring fields in political science research. Through a systematic comparison of their analytical structure accross various dimensions, we show that their conception of the economy critically shapes their understanding of politics.

Ce mémoire étudie la manière dont le cinéma d’animation et le cinéma d’horreur, deux formes cinématographiques a priori très éloignées, se rencontrent pour illustrer la souffrance du personnage animé à travers les films Beauty Water (Cho Kyung-hun, 2020) et Perfect Blue (Satoshi Kon, 1998). Cette recherche met en lumière la complexité de cette représentation ainsi que le langage esthétique neuf que ces deux registres construisent, fondé notamment sur un imaginaire propre à ces formes cinématographiques. Le réalisme spatial et socio-culturel, l’étude du corps et de la douleur physique, ainsi que la souffrance psychologique des personnages, sont au cœur de cette réflexion. Cette étude ouvre une nouvelle perspective sur la manière dont la peur et la douleur peuvent être incarnées dans le cinéma animé, plus particulièrement dans l'animation sud-coréenne et japonaise.

The focus of this paper are Reduplicated Numerals in Mandarin Chinese (Sino-Tibetan) and in Karitiana (Arikem, Tupi). Our goal is to elucidate their semantics and thus to contribute to the understanding of the relation between distributivity and individuation in the event domain. It is well known that reduplicated numerals have distributive effects across languages (Gil 1988, Balusu 2006). In this paper, we look at reduplicated numerals in two typologically unrelated languages that lack morphological Number marking on the NP/DP. We analyze the distributive effects of reduplicated numerals as generated by a pluractional operation (see also Cable 2014). By considering the semantic contribution of the numeral phrase within the pluractional operator, we wish to open a window on the delicate issue of event individuation.

In a first step, we have developed and implemented VECSEL structures, aiming at maximizing the laser output power through a proper thermal management. The fabricated VECSEL chips contain an InP-based active region for emission at 1.55 µm. A hybrid metal-GaAs/AlAs Bragg mirror is used to achieve efficient dissipation of the heat generated in the active region. The semiconductor structure is integrated to various host substrates and the VECSEL performances are investigated numerically and experimentally. VECSELs with CVD diamond substrates have the best overall performance and are promising for large output power (> 500 mW), while electroplated copper substrate is demonstrated to be a flexible and cost-effective approach for thermal management in 1.55 µm OP-VECSEL in order to achieve output power of several tens of mW to ~ 200 mW. The second part of the work is devoted to the development of SESAM structures at 1.55 µm. The structures include an active region consisting of InGaAsN / GaAs quantum wells surrounding by GaAsN planes, allowing to achieve absorption relaxation time of few picoseconds. The SESAM microcavity resonance was adjusted via a selective etching of phase layers specifically designed to control the magnitude of both the modulation depth and the intra cavity group delay dispersion of the device.Finally, assembling VECSEL and SESAM chips in a cavity, we observe experimentally that the mode-locked pulse duration could be reduced from several picoseconds to less than one picosecond when the resonance and group delay dispersion of the SESAM microcavity are tuned.

Objectifs : la fréquentation des urgences est en constante augmentation particulièrement, chez les personnes âgées. Le but de cette étude est donc d’évaluer la pertinence des passages aux urgences des personnes âgées de 75 ans et plus, et de décrire les passages inappropriés. Méthode : étude épidémiologique descriptive, rétrospective menée en juin 2019 aux urgences du centre hospitalier de Libourne. Les patients recrutés sont ceux âgés de 75 ans et plus, étant donné qu’ils présentent un risque élevé de recourir aux urgences. L’évaluation de la pertinence a été réalisée selon une grille de critères explicites contenus dans la version française de l’Appropriateness Evaluation Protocol (AEPf) modifiée pour le besoin de l’étude. Cette grille permet de distinguer les passages pertinents (AEPf+) et non pertinents (AEPf-). Résultats : environ 19.55% des passages aux urgences sont considérés AEPf-. Dans la majorité des cas, ces patients AEPf- viennent aux urgences par leurs propres moyens, prennent moins de médicaments, présentent moins de pathologies chroniques et rapportent des motifs qui diffèrent de ceux qui sont fréquemment évoqués par les AEPf+. Leur admission non pertinente au sein des urgences est à corréler avec la lenteur des procédures, l’absence de structure adaptée pouvant accueillir ces patients âgés, la longue attente des résultats ou des décisions de la famille du patient. Sur la semaine, 43% de ces patients ont été admis aux urgences le week end et majoritairement le jour plutôt que la nuit. Discussion : l’AEPf seul n’est pas suffisant pour déterminer la pertinence de l’admission du patient âgé aux urgences, d’où la nécessité de recourir à d’autres critères comme ceux utilisés dans l’Identification of Senior at Risk. Une amélioration de la formation et de l’organisation du service des urgences pourrait réduire l’engorgement causé par les passages non pertinents de même que l’amélioration du comportement médical d’amont et de l’exploitation des réseaux intra et extra hospitaliers. Conclusion : le recours non pertinent aux urgences du Centre Hospitalier de Libourne est relativement faible ce qui traduit un usage relativement adéquat. A l’avenir le développement de la filière des soins gérontologiques doit devenir une priorité et devra intégrer les structures d’urgences.

Sulfated glycosaminoglycan (GAG) analogues derived from plant, algae or microbial sourced polysaccharides are highly interesting in order to gain bioactivities similar to sulfated GAGs but without risks and concerns derived from their typical animal sources. Since the exopolysaccharide (EPS) produced by the bacterium Vibrio diabolicus HE800 strain from deep-sea hydrothermal vents is known to have a GAG-like structure with a linear backbone composed of unsulfated aminosugar and uronic acid monomers, its structural modification through four different semi-synthetic sulfation strategies has been performed. A detailed structural characterization of the six obtained polysaccharides revealed that three different sulfation patterns (per-O-sulfation, a single N-sulfation and a selective primary hydroxyls sulfation) were achieved, with molecular weights ranging from 5 to 40 kDa. A Surface Plasmonic Resonance (SPR) investigation of the affinity between such polysaccharides and a set of growth factors revealed that binding strength is primarily depending on polysaccharide sulfation degree.

In this paper, we apply an algebraic method to estimate the amplitudes, phases and frequencies of a biased and noisy sum of complex exponential sinusoidal signals. Let us stress that the obtained estimates are integrals of the noisy measured signal: these integrals act as time-varying filters. Compared to usual approaches, our algebraic method provides a more robust estimation of these parameters within a fraction of the signal's period. We provide some computer simulations to demonstrate the efficiency of our method.

En 1883, la société Claude Frères achète une fabrique d'ouate à la Haute-Goutte (Neuwiller) et la transforme en tissage. En 1907, c'est Hisler qui construit un tissage à la Haute-Goutte. Photo 3 : tissage de Hisler. Il s'agit de deux bâtiments à un niveau et deux versants symétriques, et un bâtiment à sheds (1907). Photo 4 : vue d'ensemble du tissage de Claude à la Haute-Goutte.