Portail HAL de l'Université du Littoral Côte d'Opale
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Low-lying zeros in families of Maass form L-functions: an extended density theorem
No full text22 pagesWe study the one-level density of low-lying zeros in the family of Maass form -functions of prime level tending to infinity. Generalizing the influential work of Iwaniec, Luo and Sarnak to this context, Alpoge et al. have proven the Katz-Sarnak prediction for test functions whose Fourier transform is supported in . In this paper, we extend the unconditional admissible support to . The key tools in our approach are analytic estimates for integrals appearing in the Kutznetsov trace formula, as well as a reduction to bounds on Dirichlet polynomials, which eventually are obtained from the large sieve and the fourth moment bound for Dirichlet -functions. Assuming the Grand Density Conjecture, we extend the admissible support to . In addition, we show that the same techniques also allow for an unconditional improvement of the admissible support in the corresponding family of -functions attached to holomorphic forms
Complete zooplankton size spectra re-constructed from « in situ » imaging and Multinet data in the global ocean
No full textPlankton size spectra are important indicators of the ecosystem state, as they illustrate the quantity of organisms available for higher marine food web and reflect multiple size-dependent processes. Yet, such measurements are typically biased by the available sampling methods, either disrupting fragile organisms or lacking good resolution (in size and/or time and space). In this study, we combined two of the most common approaches to measure zooplankton Normalized Biomass/Biovolume Size Spectra (NBSS) to calculate a complete zooplankton distribution for organisms larger than 1 mm. The reconstructed NBSS slopes appeared steeper and closer to those measured by the UVP5 (+7.6%) and flatter than those of the Multinet (- 20%) particularly in tropics and temperate latitudes. The overall gain in polar biomass was relatively small for reconstructed biomass compared to bulk estimates from Multinet (+0.24 mgC/m3 or +4.25%) and high from the UVP5 (+2.0 mgC/m3 or +53%). In contrast, in the tropical and temperate ecosystems, the gain in biomass was small for UVP5 (+0.67 mgC/m3 or +30.44% and +0.74 mgC/m3 or +19.59% respectively) and high for Multinet (+1.66 mgC/m3 or +136% and +3.4 mgC/m3 or +309% respectively). Given these differences, we suggest here to combine in situ imaging sensors and net data in any comprehensive study exploring key living players in the ocean ecosystem and their contributions to the biological pump
Création ou Gestion d'Entreprises et Droit
No full textInternational audienceMonsieur Clotaire MOULOUNGUI ambitionne de participer à l’octroi d’une certaine culture juridique aux créateurs, aux dirigeants et aux gestionnaires d’entreprises. Le livre (« Création ou Gestion d’Entreprises et Droit ») qu’il aura écrit à cette fin n’est pas (à l’instar d’un roman) destiné à une lecture en une traite. Il servira de préférence d’aide-mémoire à ses destinataires. Au demeurant, compte tenu de l’Internet (et de l’I.A.) il n’est plus désormais question de mémorisation de la part des lecteurs, et moins encore de leur offrir des développements volumineux qu’ils considéreraient comme rébarbatifs
Acute Effects of Daily Life Spontaneous and Structured Physical Activity on Glycemia in Children with Type 1 Diabetes
No full textInternational audienceObjectives In type 1 diabetes, glycemia management is rendered complex through the confounding influence of spontaneous physical activity (PA), particularly frequent in children. We aim to understand the glycemic effects of self-reported PA and cumulative spontaneous PA in their everyday life, controlling for carbohydrate intake and insulin.Methods In this 7-day observational study, 45 children/adolescents (21 females, 11‧7 ± 3‧4 years) wore a continuous glucose monitoring system and accelerometer, completing diaries about PA, diet, insulin. Types of PA included (i) self-reported PA and its characteristics (duration, subjective intensity) and conditions (previous sessions, timing and pre-exercise carbohydrate intake, insulin-on-board, glycemia), (ii) spontaneous cumulative PA (accelerometry) adjusted for sedentary time. Linear mixed models were used with results expressed as the estimated coefficient ‘e’. In cases of skewed continuous dependent outcomes containing a preponderance of zero % values, random-intercept binary logistic regressions were used with results expressed as odds ratios (OR).Results Accumulating moderate-to-vigorous PA during the late afternoon (e = −0‧32, P = 0‧039) was associated with decreased concomitant time spent >13‧9 mmol.L-1. Time spent >10‧0 mmol.L-1 during self-reported PA was lower when children consumed less high-glycemic-index carbohydrates the previous hour (e = +0‧49, P = 0‧034; albeit found only in one model out of two) or were physically active before the session (tendency: e = −11‧58, P < 0‧07). PA conditions were not significantly associated with hypoglycemia. Risk of spending some time < 3‧9 mmol.L-1 during sessions was higher in the case of longer PA duration (OR = 1‧02, P = 0‧008). Risk of nocturnal time < 3‧0 mmol.L-1 was greater when children performed longer duration structured PA (OR = 1‧02, P = 0‧054) or accumulated more afternoon vigorous-intensity PA (OR = 1‧06, P = 0‧04).Conclusions Increasing spontaneous active behavior during the late afternoon could help reduce day-time spent >13‧9 mmol.L-1. There is a possibility that hyperglycemia during exercise could be limited by multiplying daily PA sessions or avoiding excessive pre-exercise carbohydrate intake. However, as only sessions characteristics, especially duration, predicted time < 3‧9 mmol.L-1 during PA and < 3‧0 mmol.L-1 the following night, simplified guidelines (not considering PA conditions) on hypoglycemic risk could be developed
Implication of bone marrow adipose tissue in bone homeostasis during osteoarthritis
No full textInternational audienceObjective: To explore the role of bone marrow adipocytes (BMAds) in osteoarthritis (OA).Methods: Male and female C57BL/6 mice (n=4/group) underwent meniscectomy (MNX) or SHAM surgery. OA was determined using Osteoarthritis Research Society International (OARSI) score, and the number of perilipin+ adipocytes was quantified. Mesenchymal Stromal Cells (MSCs) from MNX and SHAM mice were differentiated into osteoblasts and adipocytes. Human adipocytes and MSCs (n=8) were enzymatically isolated from epiphyseal and metaphyseal marrow, and from subcutaneous adipose tissue (SCAT) of hip OA patients. Human OA MSCs were differentiated into osteoblasts and adipocytes (OA-Diff-hAdipo). Gene expression patterns of epiphyseal and metaphyseal BMAds, SCAT adipocytes and OA-Diff-hAdipo were evaluated by RNAseq (n=4). The effect conditioned media from OA epiphyseal bone (n=5) on the alkaline phosphatase (ALP) activity and mineralization kinetics was assessed in vitro.Results: Increase in BMAd density was positively correlated with cartilage degradation in MNX mice. OA modified the differentiation capacity of MSCs, accelerating adipocyte differentiation and failing to produce osteoblasts in both human and mice. Human epiphyseal, metaphyseal and SCAT adipocytes from the same OA patients each displayed a specific transcriptome, suggesting different functions. Enrichment analysis defined metaphyseal OA-BMAds as cells implicated in hematopoietic stem cell differentiation. On the other hand, epiphyseal OA-BMAds were considered as osteogenic cells showing an up-regulation of genes related to bone mineralization and remodeling. Specifically, OA epiphysis-secreted molecules decreased ALP activity and altered in vitro the mineralization process.Conclusion: All these results support the emergence of BMAds as new cell partners in OA, opening new venues for therapeutic approaches
Naviguer et pêcher : quand les innovations techniques redessinent les mers
No full textInternational audienc
Local optima networks for constrained search spaces
No full textInternational audienceLocal Optima Networks (LON)s have been used extensively to understand the global structure of optimisation problems and to study algorithm behaviour. The central idea is to compress the search space into a graph object capturing the local optima along with information on their basins of attraction and the connections between them. This enables the visualisation of high dimensional search spaces, and the extraction of metrics for characterising and contrasting different problem instances. In this paper we extend the canonical LON definition to encompass search spaces with constraints. We use a well-known pairwise comparison operator for constrained problems, and capture the features of the constraint violation landscape that present a challenge for such an operator, such as infeasible local traps. The concept of a constrained LON is illustrated through a range of problem instances. Most problems in the context of real-world applications have constraints. By including the notion of feasibility and constraint violation into the definition of LONs, it becomes possible to use this powerful analysis tool on a much wider range of real-world problems
Asymptotic properties of maximum composite likelihood estimators for max-stable Brown-Resnick random fields over a fixed-domain
No full textLikelihood inference for max-stable random fields is in general impossible because their finite-dimensional probability density functions are unknown or cannot be computed efficiently. The weighted composite likelihood approach that utilizes lower dimensional marginal likelihoods (typically pairs or triples of sites that are not too distant) is rather favored. In this paper, we consider the family of spatial maxstable Brown-Resnick random fields associated with isotropic fractional Brownian fields. We assume that the sites are given by only one realization of a homogeneous Poisson point process restricted to C = (-1/2, 1/2] 2 and that the random field is observed at these sites. As the intensity increases, we study the asymptotic properties of the composite likelihood estimators of the scale and Hurst parameters of the fractional Brownian fields using different weighting strategies: we exclude either pairs that are not edges of the Delaunay triangulation or triples that are not vertices of triangles.</div
Exact controllability of anisotropic 1D partial differential equations in spaces of analytic functions
No full textIn this article, we prove a local controllability result for a general class of 1D partial differential equations on the interval . The PDEs we consider take the form where 1\le N < M, , and is some linear or nonlinear term of lower order. In this context, we prove a local controllability result between states that are analytic functions. If some boundary conditions are prescribed, a similar local controllability result holds between analytic functions satisfying some compatibility conditions that are natural for the existence of smooth solutions of the considered PDE. The proof is performed by studying a nonlinear Cauchy problem in the spatial variable with data in some spaces of Gevrey functions and by investigating the relationship between the jet of space derivatives and the jet of time derivatives. We give various examples of applications, including the (good and bad) Boussinesq equation, the Ginzburg-Landau equation, the Kuramoto-Sivashinsky equation and the Korteweg-de Vries equation
