Scientific Publications of the University of Toulouse II Le Mirail
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Reducing Stochastic Games to Semidefinite Programming
No full textInternational audienceWe present a polynomial-time reduction from max-average constraints to the feasibility problem for semidefinite programs. This shows that Condon’s simple stochastic games, stochastic mean payoff games, and in particular mean payoff games and parity games can all be reduced to semidefinite programming
Tourisme balnéaire et développement territorial : le cas de la ville côtière de Mbour au Sénégal
No full textBeach tourism is booming on Africa's coasts, bringing new opportunities to boost local economies. This thesis examines the role that this activity can play in the sustainable territorial development of coastal areas, questioning its economic, social and environmental impact. By analyzing the dynamics of tourism, we seek to understand how to reconcile attractiveness with the preservation of natural resources. While seaside tourism creates jobs, improves infrastructures and enhances the value of the region, it also generates strong pressures on ecosystems and traditional lifestyles. This study underlines the urgent need to build a more responsible form of tourism, based on participatory governance, so that the benefits actually accrue to the region. Ultimately, it invites us to reflect : can tourism be a driver of development without betraying the identity and natural wealth of African coasts ?Le tourisme balnéaire connaît un essor considérable sur les côtes africaines, apportant de nouvelles opportunités pour dynamiser les économies locales. Ce mémoire étudie le rôle que peut jouer cette activité dans le développement territorial durable des littoraux, en questionnant son impact à la fois économique, social et environnemental. À travers l’analyse des dynamiques touristiques, nous avons cherché à comprendre comment concilier attractivité et préservation des ressources naturelles. Car si le tourisme balnéaire crée des emplois, améliore les infrastructures et valorise les territoires, il engendre aussi de fortes pressions sur les écosystèmes et les modes de vie traditionnels. Ce travail souligne l’urgence de construire un tourisme plus responsable, appuyé sur une gouvernance participative, pour que les bénéfices profitent réellement aux territoires. En définitive, il nous invite à réfléchir : le tourisme peut-il être un moteur de développement sans trahir l’identité et la richesse naturelle des littoraux africains
Investigating extreme cases in Wikipedia talk pages: Some insights on user behaviours
No full textInternational audienceThe study presented in this paper is part of a larger project that explores various dimensions of Wikipedia talk pages, in which we propose to examine the dynamics of interaction between Wikipedians. Based on a dataset of 3.4 million threads from the English Wikipedia talk pages, we specifically focus on extreme cases. Our approach targets the general and structural features of these threads (who posts when, and in which order) and not primarily their language content. After a quantitative overview of the main structural characteristics of our dataset, focusing on the general features of the discussions, we select a subset of items for a closer examination. These include the most prolific users, the longest threads (in terms of total duration, number of posts or number of distinct users involved) and the longest monologues (threads with multiple posts by the same single user). In each case we propose a coarse-grain typology and a number of features that relate to the origin of the underlying behaviours. We assume that the analysis of such extreme cases can help to better understand expected and unexpected interactions between Wikipedians. In other words, extreme cases may help us better under stand various phenomena in Wikipedia dynamics of interaction, but also in the way individuals interact in writing on the Web. Indeed, some of the observed behaviours are mainly specific to the collaborative editing objective and context of Wikipedia, such as polls, logbooks, diaries, to-do lists etc. But other unusual types of discussion (long-time exchanges, monologues) can be expected to be found in other forms of asynchronous computer-mediated communication
Nociceptin/OrphaninFQ Receptor Modulates the Maturation of Adult-Born Neurons in the Mouse Dentate Gyrus Under Physiological Conditions and in a Chronic Stress Model
No full textInternational audienceNeurogenesis persists in the adult dentate gyrus (DG) of the hippocampus, playing a critical role in memory and stress adaptation. Dysregulation of this process is implicated in cognitive deficits and depressive behaviors induced by chronic stress, while classical antidepressants are known to enhance neurogenesis. The Nociceptin/Orphanin FQ (N/OFQ) system, comprising N/OFQ and its NOP receptor, modulates memory and the stress response, yet its role in adult neurogenesis remains underexplored. Here, we investigated the impact of N/OFQ signaling on neurogenesis in the mouse DG using genetic and pharmacological approaches under basal and chronic stress conditions. In constitutive NOP receptor knockout (KO) mice, adult neurogenesis was only mildly altered, with subtle changes in neuronal maturation. However, spine density in 4-week-old adult-born DG neurons increased following conditional NOP Receptor KO in the DG. The increase was specific to stubby and thin spines, while mature mushroom spine density decreased. When NOP KO was restricted to newly born neurons, no significant differences were observed in spine density suggesting that the absence of NOP receptors in mature DG neurons influences the local environment to regulate spinogenesis in adult-born neurons indirectly. Finally, chronic corticosterone exposure impaired spinogenesis in immature neurons, and this was mitigated by systemic administration of a NOP antagonist. Our findings suggest that N/OFQ signaling indirectly regulates the maturation and connectivity of adult-born neurons through modulation of local and distal inputs. This regulation may contribute to the antidepressant and pro-cognitive effects of NOP receptor antagonists
Size Profiling of cfDNA with μLAS for Agnostic Biomarker Identification
No full textCell-free DNA (cfDNA) in human blood plasma is a valuable biomarker for various physiological and pathological conditions. Specific genetic and epigenetic alterations associated with diseases can be detected in the blood, offering a non-invasive method for monitoring at-risk patients and assessing therapy efficacy.While high-sensitivity PCR-based technologies have demonstrated proof-of-principle, the low concentration of cfDNA complicates analytical routines, especially when rapid results are needed. Additionally, these technologies often require knowledge of the disease's genetic background, increasing the risk of false-negative diagnostics.We have developed the µLAS technology for high-sensitivity DNA sizing in just 25 minutes. µLAS utilizes electrohydrodynamic separation and concentration of DNA in funnel-like microfluidic channels. Unlike competing assays, µLAS operates effectively in plasma with high salt concentrations, enabling the collection of cfDNA biomarkers with excellent selectivity, independent of prior genetic knowledge.In this talk, we will present the µLAS technology and discuss our findings from clinical applications
Exploring Plasma Cell-Free DNA Structure for Agnostic Biomarker Identification
No full textInternational audienceAbstractBACKGROUND : Cell-free DNA (cfDNA) is a promising biomarker, offering both disease-specific insights (e.g., mutations) and systemic, agnostic information (e.g., fragmentomics). Our team has recently pioneered the BIABooster technology, which, to the best of our knowledge, represents the most sensitive DNA sizing technology available (1 fg/µL). This innovation enables the characterization of cfDNA in plasma without purification within minutes. Utilizing this technology, we have demonstrated that the cfDNA size profile serves as an agnostic biomarker, differentiating advanced lung cancer patients from healthy controls.AIM : We hypothesize that the analysis of cfDNA size profiles can be further enhanced through a deeper understanding of cfDNA structure in plasma. CfDNA is known to associate with various biological solutes in the bloodstream, including lipoproteins and extracellular vesicles (EVs). These interactions are likely modulated in disease conditions but remain poorly characterized in terms of their molecular diversity and functional relationship to cfDNA stability.RESULTS : In this study, we present an analytical workflow for plasma fractionation based on size, density, or combined size-density parameters. We detail the cfDNA composition of the resulting fractions, revealing that in healthy individuals, cfDNA is not associated with EVs. Instead, it is found within small, non-EV particles whose density correlates with cfDNA size. Applying this analytical workflow to cancer patient samples, we suggest that the structure of cfDNA is altered in cancer, providing new avenues for biomarker discovery and clinical application
Co-construction de communs numériques organisationnels et territoriaux : une approche interdisciplinaire, inclusive et ancrée dans les réalités sociales
No full textInternational audienceCo-construction de communs numériques organisationnels et territoriaux : une approche interdisciplinaire, inclusive et ancrée dans les réalités sociale
Recent significant drying in Central Congo Basin linked to weakened Walker circulation and warmer Atlantic
No full textInternational audienceThe Congo River Basin (CRB), hosting the second-largest tropical forest on Earth, is of global significance for the water and carbon cycles. Its population and ecosystems are also strongly dependent on freshwater availability, which is increasingly threatened by current climate change and deforestation. Persistent drought conditions in CRB have been reported, but their drivers and impacts on the basin's hydrology remain unknown. Here, we analyze 42 years (1981-2022) of atmospheric and hydrological variability to show that the drying trend in Central Congo is linked to reduced atmospheric moisture convergence and precipitation, primarily during the rainiest period. This trend correlates with a weakening of the Walker circulation and an increase in Sea Surface Temperature in the Central Eastern Tropical Atlantic Ocean which influences moisture convergence over the Central Congo with a similar to 3-month lag. Our findings emphasize the need for integrative atmospheric and hydrological approaches to address CRB's freshwater and forest vulnerability to climate change
Exploiting Term Sparsity in Symmetry-Adapted Basis for Polynomial Optimization
No full textInternational audiencePolynomial optimization problems are infinite-dimensional, nonconvex, NP-hard, and are often handled in practice with the moment-sums of squares hierarchy of semidefinite programming bounds. We consider problems where the objective function and constraint polynomials are invariant under the action of a finite group. The present paper simultaneously exploits group symmetry and term sparsity in order to reduce the computational cost of the hierarchy. We first exploit symmetry by writing the semidefinite matrices in a symmetry-adapted basis according to an isotypic decomposition. The matrices in such a basis are block diagonal. Secondly, we exploit term sparsity on each block to further reduce the optimization matrix variables. This is a non-trivial extension of the term sparsity-based hierarchy related to sign symmetry that was introduced by two of the authors. Our method is compared with existing techniques via benchmarks on quartics with dihedral, cyclic and symmetric group symmetry
Visuo-vestibular integration for self-motion: human cortical area V6 prefers forward and congruent stimuli
No full textInternational audienceThe integration of visual and vestibular input is crucial for self-motion. Information from both sensory systems merges early in the central nervous system. Among the numerous cortical areas involved in processing this information, some (V6 and the ventral intraparietal area –VIP) respond specifically to vestibular anteroposterior information. A series of experiments were carried out to further understand the involvement of these and other areas in self-motion processing when vestibular and visual information are combined with varying congruence and direction parameters. Fifteen subjects underwent an MRI session while receiving visual (optic flow patterns) and galvanic vestibular stimuli, mimicking six conditions: (1) visual forward, (2) visual backward, visual forward with (3) congruent or (4) incongruent vestibular information, visual backward with (5) congruent or (6) incongruent vestibular information. At the voxel-wise level, adding vestibular stimulation to optic flow stimulation activated several bilateral areas located predominantly in the insular cortex. However, the region of interest (ROI) analysis of these areas indicated that none of them exhibits any specificity for the forward/backward direction or for the visuo-vestibular congruency. By extending the ROI approach to other well-known visuo-vestibular areas, we found that the parieto-occipital area V6 is unique in showing not only an increased level of activation for concurrent visual and vestibular stimulation, but also a marked preference when these signals are congruent and specify forward motion. Since area V6 is the only region more active when both visual and vestibular signals specify the most common self-motion direction (i.e. forward self-motion), our results support the view that this area plays a crucial role in visuo-vestibular integration during locomotion. This could be the first step towards the construction of a conscious perception of self-motion, possibly involving other areas