Science & Mathematics

In this thesis, I examine the opportunities and challenges that regions in the European Union (EU) face during the process of European integration. EU membership grants access to the world's largest common market, but not all regions benefit equally. Peripheral regions or those specialized in less competitive industries may encounter significant obstacles. To counteract such disparities, the EU employs Structural and Investment Funds (EU Funds). The first chapter introduces a novel instrumental variable to address endogeneity concerns and incorporates potential spatial spillovers. The results show that EU Funds foster regional growth, with spillover effects that can even surpass direct impacts. The second chapter investigates the consequences of the Eastern enlargements for border urban municipalities. While borders often constrain development, EU accession transforms them into internal regions of the common market, potentially stimulating growth. The analysis reveals that the benefits of enlargement depend on local characteristics, the nature of the border, and the countries on both sides, with evidence highlighting the role of market potential. Finally, the third chapter studies the 2004 enlargement from the perspective of firms. The findings suggest that firms in new member states close to EU15 borders experience declining profitability relative to interior firms. However, smaller firms in these areas display relatively higher profitability, pointing to competitive pressures from EU15 firms as a potential deterrent for larger firms.

The school quasi-market in French-speaking Belgium is characterised by segregation of various types. Efforts to apply measures that encourage greater social mixing have met with stiff resistance and various difficulties. In 2008 and 2009, a significant amount of turbulence was caused by the application of the "social mixing" law influencing the registration procedures for students in secondary education. The purpose of this article is to present some results from a prospective research project that investigated the possibility of modifying the formula for financing schools, the foundation of the quasi-market mechanism. To do this, a generalised formula for allocating funds to schools according to need is proposed on the basis of legislation currently in force in the French Community of Belgium. Then, the solution tested is presented with a financing formula that takes into account indicators of the social composition of the school population. Various scenarios of differentiated financing of schools according to these indicators are presented, through simulations using real data on the effects of these scenarios in terms of gains and losses first for all schools, and then for different contrasting schools thereafter. Finally, the implications of these scenarios are discussed and put into perspective with respect to the different solutions considered since 2005 in French-speaking Belgium.

The purpose of this work is to isolate and characterise the light fraction of Safaniya, a conventional nonbiodegraded type II crude oil. This fraction is devoted to perform a kinetic study on the thermal stability of the light aromatic fraction of crude oil. The light cut

Rivers and streams in urban areas are losing their natural environ-mental qualities. A lack of river management and insufficient interest on the part of municipal authorities has become the norm, especially in the case of small watercourses. Here, an interdisciplinary approach to landscape-level degradation is applied to selected catchments in the Czech Republic (the streams known as the Lačnovský and the Leskava). This approach includes basic geographical approaches to the quantification of the relationship between anthropogenic pressure and ecological stability. The methods employed include hy-dromorphological field research, identification of changes in land use, and an inventory of anthropogenic landforms.The existence of urban stream syndrome was established in model catchments. Parameters for these areas were compared with values for susceptibility to natural risk and preliminary results show a spatial pattern consistent with the areas at most risk also being prone to flooding. The observations were subjected to cartographic visualization and enriched with thematic and temporal uncertainty features, thus refining the results and highlighting any ambiguity.

When analyzing microbial communities, an active and computational challenge concerns the categorization of 16S rRNA gene sequences into operational taxonomic units (OTUs). Established clustering tools use a one pass algorithm in order to tackle high numbers of gene sequences and produce OTUs in reasonable time. However, all of the current tools are based on a crisp clustering approach, where a gene sequence is assigned to one cluster. The weak quality of the output compared to more complex clustering algorithms, forces the user to post-process the obtained OTUs. Providing a membership degree when assigning a gene sequence to an OTU, will help the user during the post-processing task. Moreover it is possible to use this membership degree to automatically evaluate the quality of the obtained OTUs. So the goal of this work is to propose a new clustering approach that takes into account uncertainty when producing OTUs, and improves both the quality and the presentation of the OTUs results.

Invariance times are stopping times τ such that local martingales with respect to some reduced filtration and an equivalently changed probability measure, stopped before τ , are local martingales with respect to the original model filtration and probability measure. They arise naturally for modeling the default time of a dealer bank, in the mathematical finance context of counterparty credit risk. Assuming an invariance time endowed with an intensity and a positive Azéma supermartingale, this work establishes a dictionary relating the semimartingale calculi in the original and reduced stochastic bases, regarding in particular conditional expectations, martingales, stochastic integrals, random measure stochastic integrals, martingale representation properties, semimartingale characteristics, Markov properties, transition semigroups and infinitesimal generators, and solutions of backward stochastic differential equations.

First campaign of excavations at the medieval Islamic archaeological site of Bilet (Eastern Tigray, Ethiopia). Excavation of the ruined building on a terrace 200 m away. south of the open soundings in the cemetery of Bilet. View of the "Qubba" from the east during excavation. Circular house interior space in the foreground. Hiluf Berhe (Mekelle University) and Deresse Ayenachew (Debre Berhan University, HornEast project) are preparing the photography of the excavation.

The zebrafish is one of the most widely adopted animal models in both basic and translational research. This popularity of the zebrafish results from several advantages such as a high degree of similarity to the human genome, the ease of genetic and chemical perturbations, external fertilization with high fecundity, transparent and fast-developing embryos, and relatively low cost-effective maintenance. In particular, body translucency is a unique feature of zebrafish that is not adequately obtained with other vertebrate organisms. The animal’s distinctive optical clarity and small size therefore make it a successful model for optical modulation and observation. Furthermore, the convenience of microinjection and high embryonic permeability readily allow for efficient delivery of large and small molecules into live animals. Finally, the numerous number of siblings obtained from a single pair of animals offers large replicates and improved statistical analysis of the results. In this review, we describe the development of opto-chemical tools based on various strategies that control biological activities with unprecedented spatiotemporal resolution. We also discuss the reported applications of these tools in zebrafish and highlight the current challenges and future possibilities of opto-chemical approaches, particularly at the single cell level.

With 8,24 GtCO2 emitted in 2019 (pre-COVID), the transport sector is responsible for around 25% of total CO2 emissions worldwide [1] and more than 31% in France (2021) [2]. Moreover, this sector contributes to NOx and particles emissions which are harmful both for the environment and human health [2]. In this context, research on electrification and alternative fuels rallies scientists and industries. While batteries and electrical engines seem a promising solution for individual vehicles, thermal engines with carbon-free fuels seem to be better suited for certain applications, such as trucks, trains, or ships [3]. As a versatile energy carrier and carbon free fuel, hydrogen is considered one key element for decarbonization, but it faces important challenges, such as storage and transportation [3]. Ammonia, another form of the hydrogen, is more and more considered as an efficient hydrogen carrier [4]. Hydrogen and ammonia can be directly used as fuel but with several differences compared to conventional hydrocarbon fuels [4]. To be efficient, existing thermal engines must be adapted to these new fuels. While an increasing number of studies focus on the optimisation of engine design [5–7], some compatibilities must be assessed for these molecules with a particular reactivity, as with the lubricant. In thermal engines, lubrication is a key challenge to ensure moderate fuel consumption, high energetic yield, and engine durability. The lifetime of lubricants is usually determined by their consumption rate, and resistance to oxidation. Oxidation engenders impurities, degradation of the lubricants’ integrity and modification of their friction reducing ability [8]. These new alternative fuels impose new constraints, the effect of which regarding lubricants’ integrity and properties must be studied to guarantee proper functioning and reasonable drain intervals. The effect of ammonia, hydrogen and their blends on lubricants in thermal engines is a relatively new topic in the literature [9–11]. Yet, lubricants degradation processes have been studied in other contexts, with hydrocarbon fuels [8,12], or in compressors using ammonia as a refrigerant for example [10]. This work presents a synthesis of phenomena observed in the literature which could take part in the ageing of lubricants in ammonia and/or hydrogen engines, with a special focus on ammonia. The methodology chosen to perform lubricant study is described here.

Cet article interroge la façon dont les conduites et les représentations langagières se sont façonnées dans le temps long de l'histoire et comment la communauté des scripteurs contemporains écrit aujourd'hui sur les plateformes numériques. Si les idéologies qui imprègnent les activités (écrites et parlées) ont connu tantôt grandeur tantôt déclin, conditionnées par les vecteurs historique, social ainsi que par les territoires scientifiques, nous explorons à partir des résultats d'une recherche comment les libertés d'expression qui donnent lieu à des transformations de formes et de normes se construisent (ou se déconstruisent). Enfin, cette recherche questionne le statut à donner à ces phénomènes instables et en constante évolution.

Le Canal de Sardaigne est installé sur un segment actuellement immergé de la branche Apennino-Maghrébide de la Chaîne Alpine. Orienté WSW-ENE il assure une communication profonde entre les bassins océaniques Algéro-LiguroProvençal et Tyrrhénien. Les structures de ce domaine résultent de la superposition de deux régimes tectoniques successifs en compression puis en extension, se traduisant par un épaississement crustal suivi d'un réarnincissement. Ce type d'évolution caractéristique des chaînes de collision peut être étudié dans le Canal de Sardaigne où les signatures morphologiques et structurales sont claires car, d'une part l'extension "postorogénique" y est modérée et d'autre part, le domaine étant immergé a été protégé de l'érosion aérienne. L'utilisation des submersibles, et en particulier celle du submersible CYANA dont la maniabilité est tout à fait exceptionnelle, permet une observation détaillée des structures in situ et d'effectuer des prélèvements très bien localisés, voire parfois de récupérer des échantillons orientés. Dans la deuxiéme partie, on peut tenter de reconstituer l'évolution du canal au Néogène. Elle s'inscrit dans celle, plus globale, de la Méditerranée Occidentale depuis l'Oligocène. Le canal, au carrefour de plusieurs domaines continentaux et océaniques, est un lieu d'interactions entre des systèmes d'ouverture, de collision et de coulissage. De son ouverture aux dépens d'un orogène, il hérite une structure fortement asymétrique. La marge sarde du canal possède une structure de marge passive typique, la marge tunisienne une structure plus originale liée à la présence du socle calabro-péloritanokabyle débité en écailles et d'une importante série sédimentaire miocène pré-rift. Les structures sont mises en valeur par érosion différentielle, essentiellement au Messinien.