Science & Mathematics

Often, solid matter is separated from particle-laden flow streams using electrospun filters due to their high specific surface area, good ability to capture aerial particulate matter, and low material costs. Moreover, electrospinning allows incorporating nanoparticles to improve the filter's air filtration efficiency and bacterial removal. Therefore, a new, improved polyacrylonitrile (PAN) nanofibers membrane that could be used to remove air pollutants and also with antibacterial activity was developed. We engineered three different filters that are characterized by the different particles embedded in the PAN nanofibers: titanium dioxide (TiO 2), zinc oxide (ZnO), and silver (Ag). Then, their filtration performance was assessed by quantifying the filtration of sodium chloride (NaCl) aerosol particles of 9 to 300 nm in diameter using a scanning mobility particle sizer. The TiO 2 _F filter displayed the smallest fiber diameter and the highest filtration efficiency (≈100%). Conversely, the Ag_F filter showed the highest quality factor (≈0.06 Pa −1) because of the lower air pressure drop. The resulting Ag_F nanofibers displayed a very good antibacterial activity using an Escherichia coli suspension (10 8 CFU/mL). Moreover, the quality factor of these membranes was higher than that of the commercially available nanofiber membrane for air filtration.

Objectifs : La riziculture dans la plaine de la Ruzizi est un pilier économique essentiel, mais elle fait face à de nombreux défis, notamment l'insécurité persistante dans les périmètres irrigués. L'objectif de l'étude est d'analyser les perceptions des riziculteurs sur les défis entravant les rendements du riz dans la plaine de la Ruzizi. Méthodologie : La Méthodologie mobilisée est l'échantillonnage probabiliste : l'échantillonnage aléatoire simple impliquant 196 riziculteurs répartis dans trois périmètres irrigués stratégiques (Luberizi, Sange et Kiliba). Résultats : Cette étude met en évidence une pléthore de contraintes majeures qui asphyxient les efforts des riziculteurs : le déficit d'accès au crédit, l'insécurité persistante caractérisée par des enlèvements et des violences, le repiquage tardif, forte densité par poquet, sarclage tardif, la prolifération des adventices, des maladies et ravageurs, la dégradation des infrastructures d'irrigation, le manque d'accès aux intrants agricoles de qualité et l'utilisation de variétés de riz moins résistantes nuisent le rendement du riz. Les répercussions socio-économiques de l'insécurité dans ces périmètres irrigués : une diminution significative des revenus, une migration forcée des riziculteurs, ainsi qu'une perturbation des cycles de production qui fragilise les structures socio-culturelles et génère des tensions intercommunautaires. Recommandations : Pour améliorer le rendement du riz, il est essentiel de se concentrer sur deux aspects clés : la pacification des périmètres irrigués et la modernisation des pratiques agricoles, avec une attention particulière sur la promotion du développement durable de la riziculture afin de renforcer la résilience des communautés locales.

In French teaching practices there is currently a lack of consideration for the decimal (base ten) principle of numeration system for whole numbers. This is the reason why we implemented two experiments to strengthen this principle, giving a key role to the use of numeration units (ones, tens, hundreds …). The first one was led in the context of designing a resource for teachers in grade 3, the second one involved training teachers in grades 1 and 2. We analyze how students and teachers take into account numeration units and put them in relation with standard representations of numbers. Both exemplify the complexity of the teaching-learning process of numeration.

In recent years, there has been a growing interest for probabilistic data management. We focus on probabilistic time series where a main characteristic is the high volumes of data, calling for efficient compression techniques. To date, most work on probabilistic data reduction has provided synopses that minimize the error of representation w.r.t. the original data. However, in most cases, the compressed data will be meaningless for usual queries involving aggregation operators such as SUM or AVG. We propose PHA (Probabilistic Histogram Aggregation), a compression technique whose objective is to minimize the error of such queries over compressed probabilistic data. We incorporate the aggregation operator given by the end-user directly in the compression technique, and obtain much lower error in the long term. We also adopt a global error aware strategy in order to manage large sets of probabilistic time series, where the available memory is carefully balanced between the series, according to their individual variability.

Wheat has become the major source of energy and protein for human beings since it is the second largest crop grown in the world after rice. Knowledge of wheat grain composition is fundamental for developing high quality wheat. Understanding of the mechanisms involved in wheat grain development (particularly in maternal tissue) is one of the main area of research nowadays. First proteomics attempt to provide a mechanism to characterize changes in gene expression is presented in this study. Quantitative and qualitative variations of proteins from 0 to 31 days after pollination of peripheral layers of wheat grain were studied.

The aspartic proteinase cardosin A is a vacuolar enzyme found to accumulate in protein storage vacuoles and lytic vacuoles in the flowers and in protein bodies in seeds of the native plant cardoon. Cardosin A has been first isolated almost two decades ago and has been extensively characterized since, both in terms of distribution within the tissues and of enzyme biochemistry. In the native system, several roles have been addressed to cardosin A in reproduction, mobilization of reserves and membrane remodeling. To participate in such diverse events, cardosin A must accumulate and travel to different compartments inside the cell: protein storage vacuoles, lytic vacuoles, cytoplasmic membrane (and eventually outside the cell). However, not much information is available regarding cardosin A biogenesis, sorting or trafficking to the different compartments. Recent studies have approached the expression of cardosin A in Arabidopsis thaliana and Nicotiana tabacum. These preliminary observations were the starting point of a detailed study of cardosin A expression, localisation, sorting and trafficking routes, resourcing to several and very different methods. It has been showed that transient expression of cardosin A in Nicotiana tabacum leaf is a good system to explore cardosin A trafficking inside the cell, as the protein is processed in a similar manner as the control and accumulates in the vacuole. Furthermore, an Arabidopsis thaliana line expressing cardosin A under an inducible promoter was explored to understand cardosin A dynamics in terms of vacuolar accumulation during seed germination events. Similarly to the Nicotiana tabacum one, this system was also validated for cardosin A expression and it allowed to conclude that the protein’s expression did not retrieved any phenotype to the cells or individuals. However, experiments conducted in BY-2 cells revealed to be inconclusive since cardosin A expression in this system is not predictable. The data obtained along this work using several cardosin A mutated forms, lacking specific domains or point-mutated, allowed to determine that cardosin A has two Vacuolar Sorting Determinants in its protein sequence: the PSI, an unconventional sorting determinant, and the C-terminal peptide, a C-terminus sorting determinant by definition. Furthermore, it was also demonstrated that each domain represents a different route to the vacuole: the PSI bypasses the Golgi Apparatus and the C-terminal peptide follows a classic Endoplasmic Reticulum-Golgi Apparatus-Prevacuole route to the vacuole. This difference in the trafficking routes is not observed for cardosin B sorting determinants as both the PSI and C-terminal peptide from cardosin B needs to pass the Golgi Apparatus to reach the vacuole. A putative role for glycosylation in the trafficking routes is further discussed as cardosin A PSI, contrary to cardosin B, is not glycosylated. The production of mutants affecting cardosin A glycosylation sites supported this idea. Moreover, cardosin A expression in germinating Arabidopsis thaliana seeds revealed a differential accumulation in non-germinated and germinated seedlings. Cardosin A was detected along the secretory pathway to the Protein Storage Vacuole in association with the Endoplasmic Reticulum, Golgi Apparatus, Prevacuole and newly formed Lytic Vacuoles. The drug Brefeldin A caused the protein to be retained in the Golgi Apparatus, despite some amount being still detected in the vacuole, not being clear if the Golgi Apparatus bypass observed in Nicotiana tabacum leaves occurs in this system. As a whole, cardosin A confirmed to be a good model to study vacuolar sorting in these two systems that complement each other in terms of approaches available. This study provided good results in order to understand in more detail cardosin A biology in particular and vacuolar trafficking of plant Aspartic Proteinases as a group.

L’étude qualitative présentée dans le cadre de ce mémoire porte sur l’expérience des travailleuses rémunérées dans le secteur associatif. Par le prisme du travail engagé dans les questions environnementales et sociales, cet écrit met en lumière les enjeux liés au travail associatif. Un focus est mis sur les salariées et la volontaire en service civique d’une petite association, dite engagée sur ces questions. J’y dresse leur portrait, le regard qu’elles portent sur leur travail et la posture professionnelle qu’elles adoptent. Il en ressort un choix de lier conviction et rémunération, une similitude dans les parcours de vie, des conflits éthiques internes et une puissance du collectif qui nourrit l’association. Ces résultats imagent les questions liées à la crise environnementale et sociale, les transformations profondes du rapport au travail des français.es, ainsi que l’essor du monde du travail associatif et ses particularités.

This review describes target-enrichment approaches followed by next generation sequencing and their recent application to the research and diagnostic field of modern and past infectious human diseases caused by viruses, bacteria, parasites and fungi.

Suppose that Σ = ∂M is the n-dimensional boundary of a con-nected compact Riemannian spin manifold (M, ,) with non-negative scalar curvature, and that the (inward) mean curvature H of Σ is positive. We show that the first eigenvalue of the Dirac operator of the boundary corresponding to the conformal metric , H = H 2 , is at least n/2 and equality holds if and only if there exists a non-trivial parallel spinor field on M . As a con-sequence, if Σ admits an isometric and isospin immersion F with mean curvature H 0 as a hypersurface into another spin Riemann-ian manifold M 0 admitting a parallel spinor field, then (1) Σ H dΣ ≤ Σ H 2 0 H dΣ and equality holds if and only if both immersions have the same shape operator. In this case, Σ has to be also connected. In the special case where M 0 = R n+1 , equality in (1) implies that M is a Euclidean domain and F is congruent to the embedding of Σ in M as its boundary. We also prove that Inequality (1) implies the Positive Mass Theorem (PMT).

We propose and analyze a scheme to entangle the collective spin states of two spatially separated bimodal Bose-Einstein condensates. Using a four-mode approximation for the atomic field, we show that elastic collisions in a state-dependent potential simultaneously create spin-squeezing in each condensate and entangle the collective spins of the two condensates. We investigate mostly analytically the non-local quantum correlations that arise in this system at short times and show that Einstein-Podolsky-Rosen (EPR) entanglement is generated between the condensates. At long times we point out macroscopic entangled states and explain their structure. The scheme can be implemented with condensates in state-dependent microwave potentials on an atom chip.