Portail HAL UNIV-RENNES
Not a member yet
180610 research outputs found
Sort by
Projets alimentaires territoriaux et stratégies alimentaires locales : une comparaison France -Brésil
No full textInternational audienceThis text compares civil society and national and local policy actions targeting the food system in Brazil and France. It shows how the two countries have adopted mirror strategies, with France relying on a multitude of local initiatives led by local authorities and civil society, with little national support, while Brazil first developed a powerful national policy influenced by organised citizen networks to disseminate it at regional and local levels.Ce texte, en version longue par rapport à l'ouvrage à paraître, compare les actions de la société civile et politiques nationales et locales visant le système alimentaire, entre le Brésil et la France. Il montre comment les deux pays ont adopté des stratégies en miroir, la France se basant sur une multitude d'initiatives locales portées par les collectivités et la société civile, avec un faible portage national, pendant que le Brésil a d'abord développé une puissante politique nationale influencée par les réseaux citoyens organisés pour la diffuser aux échelles régionale et locale
Optimal energy management in multi energy microgrid with combined heat and power system and demand side response integration
No full textInternational audienc
Les animaux dans le monde romain. Penser l’anthropocentrisme
No full textInternational audienceWhat is anthropocentrism? How does it differ from speciesism? When did our unbalanced relationship with animals begin? Why and how? This book answers these questions by going back to the roots of our culture, the Roman world, not forgetting our Greek heritage. It was then that the relationship with animals and their place within the city was theorised. Animals were also ‘animalised’, in the same way that women and barbarians were animalised. However, nothing was set in stone: some voices pleaded their cause, but were quickly silenced. Philosophers and theologians preferred to go in search of a hypothetical ‘proper of man’, while jurists enshrined his excellence in law. The book leaves no stone unturned and questions the logic behind certain practices (veterinary medicine, vivisection, zootechnics, etc.).Drawing on our history and the contributions of cognitive science and anthropology, the author proposes a redefinition of anthropocentrism and presents speciesism as a choice of civilisation to which we are heirs.Qu’est-ce que l’anthropocentrisme ? Qu’est-ce qui le différencie du spécisme ? Quand notre rapport aux animaux, si déséquilibré, s’est-il mis en place ? Pourquoi et selon quelles modalités ? C’est à ces questions que ce livre répond en revenant aux racines de notre culture, le monde romain, non sans tenir compte de l’héritage grec. C’est alors que l’on a théorisé la relation aux animaux et leur place au sein de la cité. Alors aussi les animaux ont été « animalisés », au même titre que l’on a animalisé les femmes et les barbares. Pour autant, rien n’était tracé : des voix ont plaidé leur cause, vite étouffées. Philosophes et théologiens ont préféré partir à la recherche d’un hypothétique « propre de l’homme », tandis que les juristes ont consacré son excellence dans le droit. Le livre n’écarte aucun écueil et interroge les logiques commandant certaines pratiques (médecine vétérinaire, vivisection, zootechnie…).Par le truchement de notre histoire et en se fondant sur l’apport des sciences cognitives et de l’anthropologie, l’auteur propose de redéfinir l’anthropocentrisme et présente le spécisme comme un choix de civilisation dont nous sommes les héritiers
Dynamic Multi-jet Flow Investigation for Adiabatic Cooling Applications
No full textInternational audienceIn the pursuit of sustainable cooling solutions, passive techniques have gained significant attention for their ability to reduce energy consumption in indoor and outdoor applications. Adiabatic cooling efficiently lowers air temperatures through water evaporation. The success of such a technique depends heavily on the ability of the air jet to disperse the droplets in the target volume. To improve droplet dispersion, it is necessary to enhance the entrainment capacity of the carrier air jet. This study investigates for the first-time flow entrainment intensification using lobes as vortex generators into a multi-jet diffuser for adiabatic cooling application. A multi-lobed jet diffuser consists of a tube pierced with a series of lobed orifices each is a daisy shaped orifice on a hemisphere (DOH). Such a geometry is intended to offer promising potential for improving overall performance in cooling applications compared to the convention-al multi-round jet diffuser (ROH). As a first step, before integrating water evaporation, it is essential to understand airflow dynamics under monophasic conditions. Experiments were conducted in a climatic chamber, providing precise control over temperature and airflow conditions to investigate the jet behavior by employing Particle Image Velocimetry and fast visualization techniques. The results indicate that DOH multi-jet flow expands more than traditional ROH multi-jet flow under the tested conditions. Specifically, in the minor plane, the dynamic jet widths Y0.5 and Y0.1 for DOH were 10% and 15% wider, respectively, and in the major plane, they were 12% and 13% wider supporting their superior mixing potential. These results suggest that integrating multi-lobed jets into evaporative cooling applications could enhance droplets dispersion into the target air volume
A Floyd-Warshall Approach to Value Computation in Markov Decision Processes (Extended Version)
No full textInternational audienceValue and policy iteration are classical algorithms to maximize the average discounted reward of an MDP. They rely on a breadth-first exploration strategy in the future of each state to update its value and possibly change the action policy at this state. This paper revisits this paradigm and examines a depth-first search strategy. It reformulates the average reward computation as an integral over (future) paths that is better expressed in the formalism of weighted automata. Policy evaluation can then be solved by a Floyd-Warshall algorithm, which gathers at once the rewards along possibly infinite runs. This reformulation opens the way to new approximation schemes for the value function. The same formalism also gives access to other quantities of interest, as the gradient of the average reward with respect to model or policy parameters, or the variance of the reward. The behaviors and performances of this value estimation scheme are illustrated on several benchmarks
Model Variability in Assessment of Human Exposure to Radiofrequency Fields
No full textInternational audienceThe recent advances in computational dosimetry for electromagnetics and thermodynamics are reviewed to assess human exposure to electromagnetic fields in the MHz-to-terahertz range. This review emphasizes model variability in computational dosimetry. Apart from computational electromagnetic methods and their usage, the developments in anatomical phantoms and tissue dielectric properties characterization are also surveyed. In addition, the rationale for dosimetric quantities prescribed in international exposure guidelines, such as the specific absorption rate (SAR) and absorbed power density, is revisited in relation to their correlation with local and core temperature rises in various tissues and populations. A heating factor, which is defined as a steady-state temperature rise per SAR, for the brain, eye lens, skin, and body core is evaluated to estimate heating resulting from exposure to electromagnetic fields. The transition of a physical quantity in the guidelines at 6 GHz, from SAR to the absorbed power density, is discussed along with the optimal spatial averaging volume and areas. Computational evaluations of product compliance, 5G devices, and wireless power transfer systems are also reviewed. This review aims to synthesize the current knowledge, identify key sources of computational model variability and uncertainty, and outline further research needs for setting exposure guidelines and compliance assessment
Convergence vers les lois stables pou des produits de matrices aléatoires
No full textUnder reasonable algebraic assumptions and under an infinite second order moment assumption, we show that the logarithm of the norm (log-norm) of a product of random i.i.d. matrices with entries in or in any other local field satisfies a generalized Central Limit Theorem (GCLT) in the sense of Paul Lévi.The proof is based on a weak law of large number for the difference between the log-norm of the product of the first matrices and the sum of their log-norms. This weak law of large numbers morally says that behaves like a sum of i.i.d. random variables that have a finite moment of order as long as the log-norm of each matrices has a finite moment of order q for a given .This gain of moment is the central result of the present paper and is based on the construction of pivotal times. Moreover, these results admit a nice higher rank extension when one looks at the full Cartan projection instead of the log-norm.Sous de hypothèses algébriques raisonnables et une condition de moment d'ordre infini, on démontre que le logarithme d'un produit de matrices aléatoires indépendantes et de même loi, à coefficients réelles ou dans un corps localement compact, satisfait un théorème central limite généralisé au sens de Lévi.La preuve fait intervenir une loi faible des grands nombres pour la différence entre le log de la norme du produit de matrices et la somme de leurs log-normes. Cette loi faible des grand nombres diten gros que se comporte comme une somme de variables aléatoires indépendantes dont la loi commune a un moment d'ordre fini là où le log-norme de chacune des matrices a un moment d'ordre fini pour un certain q > 0.Ce gain de moment est central dans le résultat du présent article et est obtenu via la construction de temps pivots. De plus, ces résultats admettent une généralisation en rang supérieur dès qu'on regarde la projection de Cartan totale au lieu du log-norme
Effets des animaux de compagnie sur la santé des personnes âgées : une enquête en Île-de-France
No full textInternational audienceAlors que les populations humaines tendent à vieillir de plus en plus, il devient essentiel d’identifier des leviers favorisant le bien-être des personnes âgées. Cette étude explore le rôle des animaux de compagnie dans le vieillissement en bonne santé à partir d’une enquête menée auprès de 230 personnes âgées de 62 à 93 ans en Île-de-France. Les données, recueillies par entretien à l’aide du questionnaire CAPI HANC-MINDMAP, ont permis d’analyser les effets directs et indirects de la possession d’animaux sur la santé physique et mentale des personnes interrogées. Les résultats montrent que les chiens et les chats influencent différemment la cohésion sociale et l’environnement de vie de leurs propriétaires : les chiens favorisent les interactions de quartier et l’activité physique, tandis que les chats renforcent les liens affectifs au sein du foyer. Les animaux améliorent aussi le bien-être psychologique en réduisant la solitude et en élargissant les réseaux sociaux, bien que certains propriétaires signalent un stress lié aux soins. L’étude souligne le rôle des animaux de compagnie en tant qu’interventions non médicamenteuses sur le bien-être des personnes, à la fois sources de soutien mais aussi de défis, et encourage leur intégration dans les stratégies de politiques publiques du bien-vieillir
EPH275 Urinary Dysfunction Management in Multiple Sclerosis: A Nationwide Real-Life Analysis From the French SNDS Database
No full textInternational audienceAnemia remains a major global public health concern, underscoring the need for innovative nutritional and therapeutic strategies. Indigenous food plants such as Carica papaya (pawpaw) have attracted attention as potential remedies; however, their claimed benefits require rigorous scientific confirmation through well-designed experimental models prior to clinical consideration. This study was designed to formulate and demonstrate a validated, two-stage experimental framework for the systematic assessment of plant-based anti-anemic activity, with C. papaya leaf and seed extracts used as a representative model. Anemia was experimentally induced in Wistar rats using aluminum chloride (AlCl₃) administered orally at 0.5 mg/kg daily for 14 days. The evaluation protocol consisted of two consecutive phases. In Stage 1, crude methanol extracts were screened at graded doses of 100, 300, and 500 mg/kg. Stage 2 focused on the most active extract identified in Stage 1, from which alkaloid and flavonoid fractions were isolated and tested at 75 and 150 mg/kg. Key hematological indices red blood cell count (RBC), hemoglobin concentration (Hb), packed cell volume (PCV), and full blood count were assessed throughout the 14-day treatment period. Administration of AlCl₃ produced marked anemia, evidenced by a decline in RBC from 7.15 to 5.05 × 10¹²/L and a reduction in Hb from 13.65 to 8.55 g/dL in untreated anemic controls. During Stage 1, methanol extracts of C. papaya leaves at 300 and 500 mg/kg demonstrated the strongest hematological recovery, significantly improving RBC, Hb, and PCV values toward normal ranges. In Stage 2, the leaf-derived alkaloid fraction at 150 mg/kg emerged as the most potent intervention, surpassing flavonoid fractions and exhibiting a clear dose-responsive effect. Overall, this work introduces a reliable and reproducible two-stage experimental approach for screening and characterizing plant-derived anti-anemic agents. The results highlight C. papaya leaf methanol extract, particularly its alkaloid fraction, as a promising candidate for anemia management and provide a standardized methodological framework for future studies in this area
Mind the Brain Age: How Segmentation and Template Selection Reshape Structural Connectomes
No full textDiffusion-weighted MRI samples the directional diffusion of water in vivo, and tractography uses this information to reconstruct brain fiber pathways. Mapping streamlines to an anatomical parcellation yields structural connectomes. However, in older adults, where white matter alterations and atrophy are common, the choice of reference template and tissue segmentation could be particularly consequential for obtaining accurate, interpretable structural connectomes. Using a conventional pipeline, we evaluated how these two factors, the normalization template and the segmentation used to constrain anatomically guided tractography, affect connectome estimates in cognitively healthy elderly participants. These methodological choices produced systematic and significant differences in network topology and their relationships with clinically relevant variables across standard connectome measures, particularly in patients with white matter hyperintensities. Age-appropriate normalization and lesion-aware anatomically constrained tractography yielded networks with more plausible anatomy and more consistent relationships with cognition and imaging measures, whereas unconstrained tracking inflated density without improving interpretability. These findings demonstrate that structural connectome outcomes are contingent upon templateand segmentation selection. We therefore advocate for explicit reporting of these methodological parameters and recommend the use of age-appropriate templates combined with white matter lesion-aware segmentation incorporating anatomically informed constraints