C2 interpolation of spatial data subject to arc-length constraints using Pythagorean-hodograph quintic splines

International audienceIn order to reconstruct spatial curves from discrete electronic sensor data, two alternative C2 Pythagorean-hodograph (PH) quintic spline formulations are proposed, interpolating given spatial data subject to prescribed constraints on the arc length of each spline segment. The first approach is concerned with the interpolation of a sequence of points, while the second addresses the interpolation of derivatives only (without spatial localization). The special structure of PH curves allows the arc-length conditions to be expressed as algebraic constraints on the curve coefficients. The C2 PH quintic splines are thus defined through minimization of a quadratic function subject to quadratic constraints, and a close starting approximation to the desired solution is identified in order to facilitate efficient construction by iterative methods. The C2 PH spline constructions are illustrated by several computed examples

Adaptive AR and Neurofuzzy Approaches: Access to Cerebral Particle Signatures

International audienceIn recent years, a relationship has been suggested between the occurrence of cerebral embolism and stroke. Ultrasound has therefore become essential in the detection of emboli when monitoring cerebral vascular disorders and forms part of ultrasound brain-imaging techniques. Such detection is based on investigating the middle cerebral artery using a TransCranial Doppler (TCD) system, and analyzing the Doppler signal of the embolism. Most of the emboli detected in practical experiments are large emboli because their signatures are easy to recognize in the TCD signal. However, detection of small emboli remains a challenge. Various approaches have been proposed to solve the problem, ranging from the exclusive use of expert human knowledge to automated collection of signal parameters. Many studies have recently been performed using time-frequency distributions and classical parameter modeling for automatic detection of emboli. It has been shown that autoregressive (AR) modeling associated with an abrupt change detection technique is one of the best methods for detection of microemboli. One alternative to this is a technique based on taking expert knowledge into account. This paper aims to unite these two approaches using AR modeling and expert knowledge through a neurofuzzy approach. The originality of this approach lies in combining these two techniques and then proposing a parameter referred to as score ranging from 0 to 1. Unlike classical techniques, this score is not only a measure of confidence of detection but also a tool enabling the final detection of the presence or absence of microemboli to be performed by the practitioner. Finally, this paper provides performance evaluation and comparison with an automated technique, i.e., AR modeling used in vitr

Etude du décrochement d'une flamme laminaire sous l'effet d'un champ magnétique

Dans cette étude numérique, on s’intéresse particulièrement à l’étude des mécanismes qui peuvent être induits par un gradient de champ magnétique sur une flamme laminaire de diffusion décrochée.  Cette flamme de méthane-air est issue d’un brûleur de jets coaxiaux. Les résultats obtenus montrent que le gradient de champ magnétique réduit l’intensité du gradient de fraction massique du carburant, modifiant ainsi la vitesse de propagation de la flamme

Etude de la cyclostationnarité du signal Doppler sanguin pour la détection de micro-emboles : étude préliminaire

Ce papier traite de la détection ultrasonore de micro-emboles par un système Doppler transcrânien. L'originalité de ce travail réside dans le fait que nous utilisons les propriétés cyclostationnaires du signal Doppler ultrasonore sanguin pour détecter des micro-emboles, depuis lors, masqués dans les phases de systoles-diastoles du cycle cardiaque. Dans cette étude nous évaluons théoriquement, à partir d'un modèle réaliste du signal Doppler sanguin, le spectre de corrélation. Nous proposons un paramètre informatif permettant la détection de micro-emboles et nous quantifions les performances du détecteur associé pour le comparer à un détecteur standard

Egg components and offspring survival vary with group size and laying order in a cooperative breeder

Prenatal resource allocation to offspring can be influenced by maternal environment and offspring value, and affect offspring survival. An important pathway for flexible maternal allocation is via egg components such as nutrients and hormones. In cooperative breeders, females with helpers may increase resource allocation to eggs-'differential allocation'-or reduce it-'load-lightening'. Yet, helper effects on egg composition have been poorly studied. Moreover, it is unknown how helpers' presence modulates laying order effects on egg content and survival. Here, we investigated how maternal allocation varied with group size and laying order in the cooperatively breeding sociable weaver (Philetairus socius). We estimated interactive effects of helpers and laying order on allocation to egg mass, yolk nutrients-yolk mass, proteins, lipids, carotenoids, vitamin A and vitamin E-and hormones-testosterone, androstenedione, and corticosterone. Results concurred with the 'differential allocation' predictions. Females with more helpers produced later-laid eggs with heavier yolks and more lipids, and laid eggs overall richer in lipids. Proteins, antioxidants, and hormones were not found to vary with helper number. We then analyzed how helper number modulated laying order effects on survival. Females with more helpers did not specifically produce later-laid eggs with higher survival, but eggs laid by females with more helpers were overall more likely to fledge. These findings show that some egg components (yolk mass, lipids) can positively vary according to females' breeding group size, which may improve offspring fitness

Les systèmes alimentaires : à la fois responsables et victimes du changement climatique

Les interactions entre le changement climatique et les systèmes alimentaires sont aujourd'hui largement mises en avant dans les agendas nationaux et internationaux. Le Sommet des Nations unies sur les systèmes alimentaires de 2021 a fait de la rési- lience au changement climatique une de ses priorités. De même, lors de la COP28, en 2023, 159 pays ont signé une déclaration relative à l'inclusion de l'agriculture et de l'alimentation dans leurs engagements climatiques nationaux (voir chapitre 2). En effet, les systèmes alimentaires constituent un levier pour l'atténuation, notam - ment dans les pays industrialisés, et ils sont aussi un enjeu pour l'adaptation, parce qu'ils sont directement touchés par les effets du changement climatique. Les systèmes alimentaires désignent l'ensemble des activités nécessaires pour nourrir une population : ils englobent les étapes de préproduction (la production d'intrants), la production elle-même et les étapes de postproduction (transport, transformation, distribution, consommation) et la gestion des déchets aux différentes étapes. Le terme de systèmes agri-alimentaires (ou agri-food systems pour les Anglo-Saxons) est égale- ment utilisé, notamment dans plusieurs chapitres de cet ouvrage, et recouvre de même l'ensemble des activités, de l'amont à l'aval. L'approche systémique, inhérente au terme système alimentaire, met l'accent sur les inter actions entre les différentes activités et leurs impacts en termes socio-économiques, environnementaux (dont les émissions de gaz à effet de serre, GES) et nutritionnels (David-Benz et al., 2022 ; FAO, 2018 ; HLPE, 2017). En considérant l'ensemble des étapes, les systèmes alimentaires génèrent environ un tiers de toutes les émissions anthropiques à l'échelle mondiale (Crippa et al., 2021 ; Rosenzweig et al., 2020 ; Tubiello et al., 2022). Dans le même temps, les systèmes alimentaires sont aussi affectés par le changement climatique et par ses effets. Ce chapitre examine ces deux dimensions, tout en distinguant les différentes catégo - ries de pays. En effet, les pays industrialisés, compte tenu des caractéristiques de leurs systèmes de production, de leurs chaînes d'approvisionnement et de leurs habitudes alimentaires, sont particulièrement émetteurs de GES. Les pays en développement sont eux à la fois les moins émetteurs et les plus touchés. Dans une première section, nous présenterons les différents postes d'émissions de GES des systèmes alimentaires. Puis la seconde section traitera de l'impact du changement climatique sur les systèmes alimentaires. L'accent sera mis sur l'aval, beaucoup moins documenté que l'impact du changement climatique sur la production, en soulignant les risques pour la sécurité alimentaire, notamment dans les pays à faible revenu

Towards specific guidelines for applying LCA in South contexts

The demand for LCA studies on agri-food value chains from South contexts is growing, but the application of LCA in these contexts is challenging. An initiative has been launched to formalize best practices based on the field experience from LCA experts for South contexts. Specificities of the application of LCA in these conditions relate to the diversity and complexity of production conditions and systems, the limited awareness and capacities in LCA as environmental assessment tool by stakeholders, the lack of specific background data, the scarcity and often low-quality of statistic data on studied systems, and the limits imposed to LCA commissioned from abroad. The guidelines in preparation will mainly focus on practical aspects of goal and scope definition, data collection and partnership, inventory and interpretation for key stakeholders

Effect of Restricted Preen-Gland Access on Maternal Self Maintenance and Reproductive Investment in Mallards

As egg production and offspring care are costly, females should invest resources adaptively into their eggs to optimize current offspring quality and their own lifetime reproductive success. Parasite infections can influence maternal investment decisions due to their multiple negative physiological effects. The act of preening--applying oils with anti-microbial properties to feathers--is thought to be a means by which birds combat pathogens and parasites, but little is known of how preening during the reproductive period (and its expected disease-protecting effects) influences maternal investment decisions at the level of the egg.Here, we experimentally prevented female mallards (Anas platyrhynchos) from accessing their preen gland during breeding and monitored female immunoresponsiveness (e.g., plasma lysozyme concentration) as well as some egg traits linked to offspring quality (e.g., egg mass, yolk carotenoid content, and albumen lysozyme levels). Females with no access to their preen gland showed an increase in plasma lysozyme level compared to control, normally preening females. In addition, preen-gland-restricted females laid significantly lighter eggs and deposited higher carotenoid concentrations in the yolk compared to control females. Albumen lysozyme activity did not differ significantly between eggs laid by females with or without preen gland access.Our results establish a new link between an important avian self-maintenance behaviour and aspects of maternal health and reproduction. We suggest that higher yolk carotenoid levels in eggs laid by preen-gland-restricted females may serve to boost health of offspring that would hatch in a comparatively microbe-rich environment

Intravenous versus subcutaneous tocilizumab in Takayasu arteritis: multicentre retrospective study

ObjectivesIn this large multicentre study, we compared the effectiveness and safety of tocilizumab intravenous versus subcutaneous (SC) in 109 Takayasu arteritis (TAK) patients.MethodsWe conducted a retrospective multicentre study in referral centres from France, Italy, Spain, Armenia, Israel, Japan, Tunisia and Russia regarding biological-targeted therapies in TAK, since January 2017 to September 2019.ResultsA total of 109 TAK patients received at least 3 months tocilizumab therapy and were included in this study. Among them, 91 and 18 patients received intravenous and SC tocilizumab, respectively. A complete response (NIH <2 with less than 7.5 mg/day of prednisone) at 6 months was evidenced in 69% of TAK patients, of whom 57 (70%) and 11 (69%) patients were on intravenous and SC tocilizumab, respectively (p=0.95). The factors associated with complete response to tocilizumab at 6 months in multivariate analysis, only age <30 years (OR 2.85, 95% CI 1.14 to 7.12; p=0.027) and time between TAK diagnosis and tocilizumab initiation (OR 1.18, 95% CI 1.02 to 1.36; p=0.034). During the median follow-up of 30.1 months (0.4; 105.8) and 10.8 (0.1; 46.4) (p<0.0001) in patients who received tocilizumab in intravenous and SC forms, respectively, the risk of relapse was significantly higher in TAK patients on SC tocilizumab (HR=2.55, 95% CI 1.08 to 6.02; p=0.033). The overall cumulative incidence of relapse at 12 months in TAK patients was at 13.7% (95% CI 7.6% to 21.5%), with 10.3% (95% CI 4.8% to 18.4%) for those on intravenous tocilizumab vs 30.9% (95% CI 10.5% to 54.2%) for patients receiving SC tocilizumab. Adverse events occurred in 14 (15%) patients on intravenous route and in 2 (11%) on SC tocilizumab.ConclusionIn this study, we confirm that tocilizumab is effective in TAK, with complete remission being achieving by 70% of disease-modifying antirheumatic drugs-refractory TAK patients at 6 months

Analyse du signal Doppler et instrumentation (étude et caractérisation d'emboles)

TOURS-BU Médecine (372612103) / SudocSudocFranceF