Science & Mathematics

In this paper, we propose a construction of a new BGK model generalizing the Ellipsoidal Statistical Model ([2], [19]) to the context of gas mixtures. The derivation of the model is based on the introduction of relaxation coefficients associated to some moments and the resolution of a minimization problem as in ([7], [8], [10]). We obtain in this work, an ESBGK model for gas mixtures satisfying the fundamental properties of the Boltzmann collision operator (conservation laws, H theorem, equilibrium states,. . .) and that is able to give a range of Prandtl numbers including the indifferentiability situation. subject classifications 35Q20, 35Q35 1. Introduction The complexity of the nonlinear Boltzmann operator suggests to introduce simpler kinetic models. Hence, the BGK model ([17]) which is a well known simplified kinetic relaxation model has been introduced. Its features are to replace the complicated integral of collisions by a relaxation model while keeping some important physical and mathematical properties of the interaction term (con-servation laws, H theorem, equilibrium states,. . .). The interest of these models is that they are easier to handle numerically and less costly at a computational point of view. However the extension of the BGK model to multi-component gases meets fundamental difficulties. For example, the hydrodynamic limit is much more complicated since phenomena such as diffusion or thermal diffusion must be considered. Many BGK models have been proposed up to now, but they are still unsatisfactory and have been constructed on the same manner. That is they must reproduce the rates of exchanges of impulsion and energy of the Boltzmann operator for Maxwell molecules between the different species. For example one polynomial model has been proposed in [13]. But its relaxation function being a polynom, the nonnegativity of the distribution function is not satisfied. However this model satisfies the indiffer-entiability principle stated in [13] inherited from the Boltzmann operator. That is when all the molecules have the same masses and their cross sections are equal, then the system of equations reduces to a single one by adding the distribution functions. A BGK model enjoying good mathematical properties has been derived in [1]. The main idea is to introduce only one BGK operator per species whose macrosopic parameters reproduce the interaction between each species with the others. But this model leads to uncorrect transport coefficients at the hydrodynamic limit ([21]). In [21], the authors constructed a BGK model which coincides with the Grad moments of the linearized Boltzmann operator. However the relaxation function of the model being polynomial, the nonnegativity of the distribution function is not sure. Hence the aim of this paper is to construct a BGK model that is able to recover correct transport coefficients and enjoying good mathematical properties. The question is important because in general the authors compute the hydrodynamic limit from their own model and eventually compare with the correct fluid model ([18]). In the situation of single and monospecies a BGK model leading to the correct Prandtl number has been proposed in ([19]). This model is called Ellipsoidal Statistical Model (ESBGK). But the proof of the H theorem has been shown later on ([2]). Recently,

Let $n\geq 1$, and let $\iota_{n}\colon\thinspace F_{n}(M) \longrightarrow \prod_{1}^{n}\, M$ be the natural inclusion of the $n$th configuration space of $M$ in the $n$-fold Cartesian product of $M$ with itself. In this paper, we study the map $\iota_{n}$, the homotopy fibre $I_{n}$ of $\iota_{n}$ and its homotopy groups, and the induced homomorphisms $(\iota_{n})_{\#k}$ on the $k$th homotopy groups of $F_{n}(M)$ and $\prod_{1}^{n}\, M$ for all $k\geq 1$, where $M$ is the $2$-sphere $\mathbb{S}^{2}$ or the real projective plane $\mathbb{R}P^{2}$. It is well known that the group $\pi_{k}(I_{n})$ is the homotopy group $\pi_{k+1}(\prod_{1}^{n}\, M, F_n(M))$ for all $k\geq 0$. If $k\geq 2$, we show that the homomorphism $(\iota_{n})_{\#k}$ is injective and diagonal, with the exception of the case $n=k=2$ and $M=\mathbb{S}^{2}$, where it is anti-diagonal. We then show that $I_{n}$ has the homotopy type of $K(R_{n-1},1) \times \Omega(\prod_{1}^{n-1} \mathbb{S}^{2})$, where $R_{n-1}$ is the $(n-1)$th Artin pure braid group if $M=\mathbb{S}^{2}$, and is the fundamental group $G_{n-1}$ of the $(n-1)$th orbit configuration space of the open cylinder $\mathbb{S}^{2} \setminus \{\widetilde{z}_{0}, -\widetilde{z}_{0}\}$ with respect to the action of the antipodal map of $\mathbb{S}^{2}$ if $M=\mathbb{R}P^{2}$, where $\widetilde{z}_{0}\in \mathbb{S}^{2}$. This enables us to describe the long exact sequence in homotopy of the homotopy fibration $I_{n} \longrightarrow F_n(M)\stackrel{\iota_{n}}{\longrightarrow} \prod_{1}^{n}\, M$ in geometric terms, and notably the image of the boundary homomorphism $\pi_{k+1}(\prod_{1}^{n}\, M)\longrightarrow \pi_{k}(I_{n})$. From this, if $M=\mathbb{S}^{2}$ and $n\geq 3$ (resp. $M=\mathbb{R}P^{2}$ and $n\geq 2$), we show that $\ker{(\iota_{n})_{\#1}}$ is isomorphic to the quotient of $R_{n-1}$ by the square of its centre, as well as to an iterated semi-direct product of free groups with the subgroup of order $2$ generated by the centre of $P_{n}(M)$ that is reminiscent of the combing operation for the Artin pure braid groups, as well as decompositions obtained in a previous paper. This paper is a shortened version of "The homotopy fibre of the inclusion $F_{n}(M) \longrightarrow \prod_{1}^{n}\, M$ for $M$ either $\mathbb{S}^{2}$ or the real projective plane $\mathbb{R}P^{2}$ and orbit configuration spaces", ⟨hal-01627001⟩. The main difference between the two is the statement and proof of Theorem 3.

Le travail de thèse présenté dans ce document traite de l'analyse de différentes propriétés liées à l'observabilité des systèmes à entrée inconnue par approche graphique. La simplicité de mise en œuvre de l'approche graphique permet de se défaire des difficultés numériques inhérentes aux approches géométrique et algébrique. Ce constat a conduit ces dernières décennies, à une série d'études structurelles basées sur l'approche graphique. Parmi les propriétés encore non abordées graphiquement, l'observabilité forte traduit l'observabilité des variables d'état d'un système pour toute valeur d'entrée ainsi que l'observabilité conjointe de l'état et de l'entrée. Ces propriétés plus fortes que l'observabilité simple et le diagnostic nous ont paru utiles et pertinentes à étudier. En effet, les outils d'analyse développés peuvent s'avérer importants dans le cadre de la synthèse d'observateurs ou d'estimateurs d'entrées utile à la synthèse de lois de commandes tolérantes aux défauts ou robustes aux perturbations, ou encore quand il s'agit de vérifier si la propriété d'observabilité d'un système n'est pas altérée lorsqu'il est soumis à des perturbations, voire à des défauts d'amplitude trop importante pour être négligés. Le manuscrit est structuré en trois parties. Dans la première, nous avons abordé l'analyse de différentes propriétés d'observabilité. Plus précisément, nous avons tout d'abord donné des conditions nécessaires et suffisantes d'observabilité de l'entrée et de l'état d'un système. Des conditions nécessaires et suffisantes pour l'observabilité forte d'une partie donnée des composantes de l'entrée et de l'état ont ensuite été établies. Le dernier résultat de cette partie concerne l'observabilité forte de tout l'état d'un système à entrée inconnue. Des conditions nécessaires et suffisantes ont été démontrées. La seconde partie de cette thèse a consisté à étudier le problème du placement des capteurs afin de recouvrer des propriétés d'observabilité forte lorsque les conditions de la première partie ne sont pas vérifiées. Deux cas ont été traités. Le premier concerne la propriété d'observabilité forte d'une partie donnée de l'état. La stratégie de placement de capteurs consiste alors en une condition nécessaire permettant d'imposer qu'au moins une sortie du système soit sensible à chacune des composantes de l'état devant être fortement observables, puis en un système de relations graphiques, utilisé comme condition suffisante à ce qu'une configuration de capteurs assure l'observabilité forte des composantes de l'état choisies. Le second problème de placement de capteurs a pour objectif de rendre observables toutes les composantes de l'état. Le problème a été traité en trois étapes. Pour chacune d'elles, des conditions nécessaires et suffisantes sur le placement de capteurs ont été trouvées. Le nombre minimal de capteurs nécessaire et suffisant a aussi été déterminé. Les conditions trouvées sont fondées essentiellement sur des algorithmes classiques de la théorie des graphes. La troisième partie traite de l'implémentation des résultats établis dans une boîte à outils dédiée à l'analyse structurelle (lisa) des systèmes linéaires et bilinéaires structurés. En premier lieu, les motivations qui ont conduit à la conception de cette boîte à outils sont exposées. La structure de lisa est ensuite présentée. Elle repose entièrement sur des algorithmes de base tels que la détermination des ensembles de successeurs et de prédécesseurs, le calcul des tailles de lien et de couplages maximaux entre deux ensembles de sommets et la caractérisation des ensembles de sommets essentiels dans des liens de taille maximale ou encore des séparateurs d'entrée et de sortie. Tous ces algorithmes ont des ordres de complexité polynomiaux. Nous avons montré comment en associant certains algorithmes de base, nous sommes arrivés à analyser l'observabilité de l'état et de l'entrée et à établir des conditions de détection et de localisation de défauts. Enfin, il est présenté des fonctions pouvant être rajoutées à lisa concernant différentes propriétés structurelles pour en faire un outil d'analyse plus complet.

Causal consistent reversibility blends causality and reversibility. For a concurrent system, it says that an action can be undone provided this has no consequences, thereby making it possible to bring the system back to a past consistent state. Time reversibility is considered instead in the performance evaluation field. A continuous-time Markov chain is time reversible if its behavior remains the same when the direction of time is reversed. We try to bridge these two theories by showing the conditions under which both causal consistent reversibility and time reversibility can be achieved in the setting of a stochastic process algebra.

About sixty oaks (Quercus robur), with different status of crown health, located in three plots in north eastern France were assessed for their degree of infection by C. fusipes. Baiting of Phytophthora spp. from soil was carried out at different seasons in a sub sample of these oaks. The variability of soil characteristics, such as depth to waterlogging signs and depth to a gravel layer limiting rooting was evaluated. Soil factors were tightly correlated. Infection induced by C. fusipes was significantly more severe in non-waterlogged conditions. In two plots Phytophthora spp. were present at the base of the majority of trees investigated. Success of Phytophthora isolation was significantly linked with the season. The crown health status deteriorates with increasing severity of infection by C. fusipes and with the depth to waterlogging. Conversely, Phytophthora was not correlated with crown health status.

Aujourd’hui, la mémorisation est souvent reléguée au temps hors-classe. Or, tous les élèves ne bénéficient pas du même soutien scolaire, ce qui contribue à renforcer les inégalités. En outre, ils n’adoptent pas les meilleures stratégies, comme nous le montre l’apport des neurosciences qui révolutionnent nos pratiques et représentations au sujet de la mémorisation. Ainsi, la mise en place d’outils qui ont pour objectif de favoriser la mémorisation des élèves permet de consolider les notions importantes de l’année en répondant aux exigences spiralaires et chronologiques des programmes.

Automatic sentence segmentation of spoken language is an important precursor to downstream natural language processing. Previous studies combine lexical and prosodic features, but can impose significant computational challenges because of the large size of feature sets. Little is understood about which features most benefit performance, particularly for speech data from different speaking styles. We compare sentence segmentation for speech from broadcast news versus natural multi-party meetings, using identical lexical and prosodic feature sets across genres. Results based on boosting and forward selection for this task show that (1) features sets can be reduced with little or no loss in performance, and (2) the contribution of different feature types differs significantly by genre. We conclude that more efficient approaches to sentence segmentation and similar tasks can be achieved, especially if genre differences are taken into account.

It is common knowledge that using directional antennas is often mandatory for Multi-hop ad-hoc wireless networks to provide satisfying quality of service, especially when dealing with an important number of communication nodes [1]. As opposed to their omnidirectional counterpart, directional antennas allow for much more manageable interference patterns: a receiving antenna is not necessarily interfered by nearby emitting antennas as long as this receiving antenna is not directed towards these undesired emission beams. Two nodes then need to steer one of their antennas in the direction of the other node in order to create a network communication link. These two users will then be able to, in turn, emit and receive to and from each other. The scope of this work resides in finding a centralized algorithm to governate these antenna steering decisions for all users to instantaneously provide a valid set of communication links at any time given the positions of each user. The problem that raises is then a geometrical one that implies finding topologies of network links that present satisfying throughput and overall QoS and guarantee instantaneous connectedness i.e. the computed set of links allows any user to reach any other user in a certain number of hops. Building such optimized link topologies makes further tasks, such as routing and scheduling of the network, much simpler and faster. This problem is highly combinatorial and, while it is solvable with traditional Mixed Integer Programming (MIP), it is quite challenging to carry it out in real time. For this purpose, we propose a Deep Neural Network that is trained to imitate valid, solved instances of the problem. We use the Attention mechanism [2] [3] to let nodes exchange information in order to capture interesting patterns and properties that then enable the neural network to generate valid network link topologies, even dealing with unseen sets of users positions.

In contrast to mouse embryonic stem cells and in spite of overlapping gene expression profiles, neural stem cells (NSCs) isolated from the embryonic spinal cord do not respond to physiological morphogenetic stimuli provided by Sonic hedgehog and retinoic acid and do not generate motor neurons upon differentiation. Transcription factors expressed in motor neuron progenitors during embryogenesis include Pax6, Ngn2, Nkx6.1 and Olig2, whose expression precedes that of factors specifying motor neuron fate, including HB9, Islet1 and LIM3. We showed that all these factors were present in neural progenitors derived from mouse ES cells, whereas NSCs derived from the rat embryonic spinal cord expressed neither HB9 nor Islet1 and contained low levels of Nkx6.1 and LIM3. We constructed a lentivirus vector to express HB9 and GFP in NSCs and examined the consequences of HB9 expression on other transcription factors and cell differentiation. Compared to cell expressing GFP alone, NSCs expressing GFP and HB9 cycled less rapidly, downregulated Pax6 and Ngn2 mRNA levels, produced higher proportions of neurons in vitro and lower numbers of neurons after transplantation in the spinal cord of recipient rats. Oligodendrocytic and astrocytic differentiations were not affected. HB9 expressing NSCs did not express Islet1 or upregulate LIM3. They neither responded to Sonic hedgehog and retinoic acid nor produced cholinergic neurons. We concluded that forced HB9 expression affected neurogenesis but was not sufficient to confer motor neuron fate to NSCs.

The Dynamitron and the Tandem SF6 gas, initially contained 11 % and 35 % non-condensable impurities, respectively. The gas has been purified to better than 99.9 %, using a constant temperature dynamic batch process, where the SF 6 propagation is simply delayed in an activated charcoal column at — 20 °C.

We have frozen the coherent evolution of a field in a cavity by repeated measurements of its photon number. We use circular Rydberg atoms dispersively coupled to the cavity mode for an absorption-free photon counting. These measurements inhibit the growth of a Field injected in the cavity by a classical source. This manifestation of the Quantum Zeno effect illustrates the back action of the photon number determination onto the Field phase. The residual growth of the Field can be seen as a random walk of its amplitude in the two-dimensional phase space. This experiment sheds light onto the measurement process and opens perspectives for active quantum feedback.

Aims. The effect of biogeographical processes on the spatial turnover component of beta‐diversity over large spatial extents remains scarcely understood. Here, we aim at disentangling the roles of environmental and historical factors on plant taxonomic and phylogenetic turnover, while controlling for the effects of species richness and rarity. Location European beech (Fagus sylvatica) forests in Europe. Methods. We aggregated plant species occurrences from vegetation plots in spatial grid cells of 0.25º × 0.25º to calculate the spatial turnover component of taxonomic (TBDturn) and phylogenetic (PBDturn) beta‐diversity for each cell. We also calculated the deviation of PBDturn given TBDturn (PBDdev‐turn), which measures the importance of phylogenetic turnover after factoring out taxonomic turnover. Beta‐diversity was calculated for each grid cell as the mean pairwise dissimilarity between the focal cell and all other cells. We used structural equation modeling (SEM) to examine the relationships between environmental (climate, soil pH, and distance from the geographical distribution limit of beech) and historical (distance from beech glacial refugia) predictors and beta‐diversity metrics. Results. We found a geographically consistent variation in taxonomic and phylogenetic turnover. Overall, TBDturn and PBDturn increased significantly towards more extreme climatic conditions, on more acidic soils, and towards the margins of beech distribution. The effects of environmental variables and the distance from glacial refugia on beta‐diversity metrics were mediated by species richness and rarity. PBDdev‐turn was higher in areas closer to glacial refugia. Conclusions. Continental‐scale patterns of beta‐diversity in European beech forests are the result of complementary ecological and evolutionary processes. In general, beech forests are taxonomically and phylogenetically more distinct in climatically marginal areas of their European range. However, the spatial variation of beta‐diversity in European beech forest flora is still strongly characterized by the distribution of groups of closely related species that evolved or survived in glacial refugia.

Narrow nuclear resonances, initially used to calibrate the energy of the Birmingham Radiation Centre 3MV Dynamitron, have proved useful in discovering and identifying accelerator fault conditions. Short-term energy stability (over e few minutes) of a few tens of eV is common. However, variations of many kV occur for several days before the failure of a thermionic rectifier. The beam energy ripple, as reflected in the full width at half maximum of narrow (p,γ) resonances, has also been analysed to indicate the frequency causing the bulk of the ripple, thus often leading to the identification and correction of faults. Typical faults usually produce increased ripple at either the 50 Hz or 128 kHz oscillator frequency.

The objective of this paper is to show process data captured with barcode administration system and the results of data analyses and visualizations for improving quality of care and productivity. Hospital Information System named Point-of-Act System that was designed to capture every process of all medical acts was employed to capture data of medical processes. Data of injection process was analyzed based on operative timeliness. The result shows nursing workload didn't be allocated equally through the day and some parts of injections hadn't been administrated at the right time. Improving operative timeliness can contribute to improve quality of care and productivity. This kind of process information has a possibility to provide new research opportunity to analyze outcome with context information including process information.

Entende-se as Unidades de Conservação – UC como o mais importante instrumento estratégico direcionado a proteção do patrimônio ambiental e sociocultural. Sob essa perspectiva, infere-se ao estudo o objetivo de analisar o nível de efetividade das unidades de conservação do Maranhão, se baseando nas características de uso e cobertura da terra. A partir de uma visão sistêmica que visa o desenvolvimento de avaliações ambientais interligadas a conservação e ao planejamento, o estudo analisa a dinâmica espacial a partir das métricas de paisagem referentes a área, forma, densidade e tamanho, em 11 UCs e suas respectivas zonas de amortecimento. Observa-se que cerca de 60% das UCs apresentaram aumento da fragmentação da cobertura florestal, bem como ampliação do índice de forma, tamanho número dos fragmentos, tanto em escala intra-UC quanto na área de entorno. Ressalta-se que essas tranformações foram diretamente influenciadas pelos grandes agentes sociais, atingindo diretamente o nível de efetividade das UCs do Estado. Palavras-chave: Áreas Protegidas; Dinâmica da Paisagem; Uso e Cobertura da Terra. THE PAST AND PRESENT OF THE MARANHÃO CONSERVATION UNITS, BRAZIL ABSTRACT It is understood the protect areas as the most important strategic instrument directed to the protection of the environmental patrimony and socio-cultural. With this understanding, it is inferred to the study the objective of analyzing the level of effectiveness of the protect areas of Maranhão based on the land use and coverage characteristics. Based on a systemic view aimed at the development of interrelated environmental assessments for conservation and planning, the study analyzes the spatial dynamics from the landscape metrics referring to area, shape, density and size in 11 protect areas and their respective damping. It is observed that about 60% of the protect areas presented an increase in the fragmentation of the forest cover, as well as an increase in the shape index, size of the fragments, both in the inside of protect areas scale and in the surrounding area. It is noteworthy that the great social agents, directly affecting the level of effectiveness of the state's protect areas, directly influenced these transformations.