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Local convergence rates for Wasserstein gradient flows and McKean-Vlasov equations with multiple stationary solutions
No full textNon-linear versions of log-Sobolev inequalities, that link a free energy to its dissipation along the corresponding Wasserstein gradient flow (i.e. corresponds to Polyak-Lojasiewicz inequalities in this context), are known to provide global exponential long-time convergence to the free energy minimizers, and have been shown to hold in various contexts. However they cannot hold when the free energy admits critical points which are not global minimizers, which is for instance the case of the granular media equation in a double-well potential with quadratic attractive interaction at low temperature. This work addresses such cases, extending the general arguments when a log-Sobolev inequality only holds locally and, as an example, establishing such local inequalities for the granular media equation with quadratic interaction either in the one-dimensional symmetric double-well case or in higher dimension in the low temperature regime. The method provides quantitative convergence rates for initial conditions in a Wasserstein ball around the stationary solutions. The same analysis is carried out for the kinetic counterpart of the gradient flow, i.e. the corresponding Vlasov-Fokker-Planck equation. The local exponential convergence to stationary solutions for the mean-field equations, both elliptic and kinetic, is shown to induce for the corresponding particle systems a fast (i.e. uniform in the number or particles) decay of the particle system free energy toward the level of the non-linear limit
Some reflections on the 5 th Vienna R&I policy evaluation conference
No full textInternational audienceLooking back at the structure of Vienna Evaluation Conferences• This is the fifth conference on R&I policy evaluation• They have been all driven by new issues of the time – here COVID, crisisresilience, and Transformative Innovation Policies• But de facto the conference is about new developments in the last 2/3 years• And we observe a quite similar structure between them around 4 dimensions- New methods /new processes / new data sources /and always some new theorising attempts- Evaluations issues of specific ‘subsystems’ – this year:regional innovation policies, environmental policies,higher education, large research infrastructures,firm innovation supports- Evaluations of Policy mixes and of synergies between policies(quasi absent this year)- New issues: and our of the 3 mentioned, clearly here the winner isThe evaluation of Transformative Innovation Policie
A spectral approach to the narrow escape problem in the disk
No full textWe study the narrow escape problem in the disk, which consists in identifying the first exit time and first exit point distribution of a Brownian particle from the ball in dimension 2, with reflecting boundary conditions except on small disjoint windows through which it can escape. This problem is motivated by practical questions arising in various scientific fields (in particular cellular biology and molecular dynamics). We apply the quasi-stationary distribution approach to metastability, which requires to study the eigenvalue problem for the Laplacian operator with Dirichlet boundary conditions on the small absorbing part of the boundary, and Neumann boundary conditions on the remaining reflecting part. We obtain rigorous asymptotic estimates of the first eigenvalue and of the normal derivative of the associated eigenfunction in the limit of infinitely small exit regions, which yield asymptotic estimates of the first exit time and first exit point distribution starting from the quasi-stationary distribution within the disk
Low circulating adropin concentrations predict increased risk of cognitive decline in community-dwelling older adults
No full textInternational audienceThe secreted peptide adropin is highly expressed in human brain tissues and correlates with RNA and proteomic risk indicators for dementia. Here we report that plasma adropin concentrations predict risk for cognitive decline in the Multidomain Alzheimer Preventive Trial (ClinicalTrials.gov Identifier, NCT00672685; mean age 75.8y, SD = 4.5 years, 60.2% female, n = 452). Cognitive ability was evaluated using a composite cognitive score (CCS) that assessed four domains: memory, language, executive function, and orientation. Relationships between plasma adropin concentrations and changes in CCS (∆CCS) were examined using Cox Proportional Hazards Regression, or by grouping into tertiles ranked low to high by adropin values and controlling for age, time between baseline and final visits, baseline CCS, and other risk factors (e.g., education, medication, APOE4 status). Risk of cognitive decline (defined as a ∆CCS of - 0.3 or more) decreased with increasing plasma adropin concentrations (hazard ratio = 0.873, 95% CI 0.780-0.977, P = 0.018). Between adropin tertiles, ∆CCS was significantly different (P = 0.01; estimated marginal mean ± SE for the 1st to 3rd tertile, - 0.317 ± 0.064; - 0.275 ± 0.063; - 0.042 ± 0.071; n = 133,146, and 130, respectively; P < 0.05 for 1st vs. 2nd and 3rd adropin tertiles). Normalized plasma Aß42/40 ratio and plasma neurofilament light chain, indicators of neurodegeneration, were significantly different between adropin tertile. These differences were consistent with reduced risk of cognitive decline with higher plasma adropin levels. Overall, these results suggest cognitive decline is reduced in community-dwelling older adults with higher circulating adropin levels. Further studies are needed to determine the underlying causes of the relationship and whether increasing adropin levels can delay cognitive decline
ZodiacEdge: a Datalog Engine With Incremental Rule Set Maintenance
No full textInternational audienceIn this paper, we tackle the incremental maintenance of Datalog inference materialisation when the rule set can be updated. This is particularly relevant in the context of the Internet of Things and Edge computing where smart devices may need to reason over newly acquired knowledge represented as Datalog rules. Our solution is based on an adaptation of a stratification strategy applied to a dependency hypergraph whose nodes correspond to rule sets in a Datalog program. Our implementation supports recursive rules containing both negation and aggregation. We demonstrate the effectiveness of our system on real and synthetic data
Longitudinal Associations Between ATPase Inhibitory Factor 1, Growth Differentiation Factor-15, and Nutritional Status in Older Adults From the MAPT Study
No full textGérontopôle of Toulouse 2008/French Ministry of Health Pierre Fabre Research Institute ExonHit Therapeutics SA Avid Radiopharmaceuticals IncInternational audienceBackground: Weight and appetite regulation have been associated with the expression and secretion of ATPase inhibitory factor 1 (IF1) and growth differentiation factor-15 (GDF-15), 2 potential biomarkers for age-related mitochondrial dysfunction. The aim was to explore the associations between these biomarkers and nutritional variables in the Multidomain Alzheimer Preventive Trial study.Methods: IF1 and GDF-15 plasma levels were quantified at 1-year follow-up. The nutritional status was measured using the Mini Nutritional Assessment (MNA) score variation between baseline and 1- and 2-year visits; appetite loss was extracted from the MNA. Bodyweight was measured every 6 months until the third year and then yearly until the fifth year of follow-up, and weight loss was established if the loss was greater than 5% or 10% within the past 6 or 12 months, respectively. Bidirectional associations of IF1 and GDF-15 levels with malnutrition, appetite, and weight loss were examined. The interactions between individual IF1 and GDF-15 with sex were explored.Results: Four hundred and forty-eight participants had MNA data and 1 045 had weight loss data. All the associations between IF1 levels and the MNA score, appetite loss, and weight loss were nonsignificant. Higher GDF-15 levels were cross-sectionally associated with appetite loss at the first year of follow-up, and the GDF-15 highest quartile was associated with nearly 80% higher risks of weight loss over 4 years. Interactions between IF1 and GDF-15 levels, and between these 2 markers and sex were not significantly associated with the outcomes.Conclusions: GDF-15 plasma levels were related to key malnutrition criteria
Supporting the Design of On-Site Infiltration Systems: From a Hydrological Model to a Web App to Meet Pluriannual Stormwater Volume Reduction Targets
No full textInternational audienceInfiltration-based sustainable urban drainage systems (i-SUDS) often turn out to be simple and effective solutions for on-site runoff and pollution control. Their ability to limit the discharge to sewer networks or receiving waters can be broadly assessed in terms of (pluri)annual stormwater volume reduction. Although accepted as a relevant efficiency metric, this long-term volume reduction does not integrate well in design practices that have traditionally relied on event-based approaches. This article introduces a modeling framework, involving a hydrological model and machine-learning emulation, from which a web app was developed to allow practitioners to investigate the relation between i-SUDS design and pluriannual volume reduction efficiencies. The theoretical basis for modeling and a description of the web app are first provided. A diagnosis of the hydrological model is then conducted. The uncertainty caused by model parameters that do not directly relate to i-SUDS design is evaluated through a sensitivity analysis performed over multiple design scenarios. The latter is found to be highly variable and potentially significant, thereby justifying its explicit consideration in the web app. As part of this diagnosis, the impact of a shallow groundwater or a low-permeability layer on simulated volume reduction efficiencies is later evaluated to clarify the validity domain of the model. Practical recommendations on the minimum distance to shallow groundwater or low permeability layer, for the rainfall conditions considered in the web app, are given as a function of project size and the permeability of the soil media. The applicability of the web app is later illustrated from a selection of outputs. Its outcomes are finally compared to those of a simple design rule based on the combination permanent storage (as rainfall depths) and drawdown duration targets. Results confirm the inability of such simple design rules to fully capture pluriannual volume reduction efficiency and point out the risk of oversizing i-SUDS
The effects of semantic simplifications on random BST-like expression-trees
No full textInternational audienceIn this article, we consider random expressions produced as BST-like trees (from the term BST, binary search trees), and study the effect of simple semantic reductions on them. These random trees are fast to produce and can be parametrized; that is why they are often used in benchmarks for model-checking tools. We assume the existence of an operator ⊛ that has an absorbing pattern and study the effect of the induced bottom-up reduction, which produces a semantically equivalent (and smaller) tree. Our main result concerns the expected size of a random tree, of given input size n→∞, after reduction. We show that there are two different thresholds, leading to a total of five regimes, ranging from no significant reduction at all, to almost complete reduction. We characterize these regimes completely in terms of the probability of picking the absorbing operator. Our study shows that the parameters of random BST-like trees must be considered carefully, yet, contrarily to uniform random trees, they might offer a relevant way to sample interesting random expressions in practice
Sécurité alimentaire et ressources naturelles : stratégies de diversification
No full textVoir aussi la version anglaise du livre : Sustainable Food Systems for Food Security. Need for combination of local and global approaches :https://www.quae.com/produit/1787/9782759235766/sustainable-food-systems-for-food-securityInternational audienceCe chapitre traite de deux enjeux majeurs auxquels sont confrontés les ménages ruraux en zone tropicale : préserver les ressources naturelles et assurer la sécurité alimentaire. Relever ces deux défis simultanément requiert de développer des systèmes de production efficaces, capables à la fois de garantir la sécurité alimentaire des agriculteurs et d’assurer une gestion durable des ressources naturelles. Pour ce faire, il convient de s’interroger sur les liens directs et indirects entre la sécurité alimentaire des ménages et la biodiversité à l’échelle de l’exploitation agricole et à celle du paysage
Thermal performance of a building envelope including microencapsulated phase change materials (PCMs): A multiscale experimental and numerical investigation
No full textInternational audienceThis study aims to assess the thermal behavior of a cement mortar (denoted M15D) incorporating microencapsulated biobased phase change materials at both wall and building scales. A bi-climatic chamber setup was employed to subject the wall to distinct thermal conditions simulating outdoor and indoor environments, using heating and cooling solicitations. Temperature sensors, strategically positioned at various depths, allowed the monitoring of temperature within the walls during the experiments. On a building scale, the thermal performance of M15D was predicted using two mathematical models describing heat transmission in porous systems incorporating phase-change materials. Numerical simulations were carried out using COMSOL Multiphysics and EnergyPlus software. The results obtained were validated against experimental data, at the wall scale and subsequently developed to the building scale. The outcomes highlighted that the incorporation of microencapsulated biobased phase change materials significantly influences both building energy consumption and interior temperature. The heat storage capacity offered by M15D demonstrated a significant impact on thermal performance, leading to energy savings of up to 33% for heating and 31% for cooling, contingent on climate conditions. In conclusion, the integration of biobased phase change materials in the cement mortar (M15D) displays benefits in enhancing thermal performance at building scales