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Backstepping for partial differential equations: A survey
No full textInternational audienceSystems modeled by partial differential equations (PDEs) are at least as ubiquitous as those by nature finite-dimensional and modeled by ordinary differential equations (ODEs). And yet, systematic and readily usable methodologies, for such a significant portion of real systems, have been historically scarce. Around the year 2000, the backstepping approach to PDE control began to offer not only a less abstract alternative to PDE control techniques replicating optimal and spectrum assignment techniques of the 1960s, but also enabled the methodologies of adaptive and nonlinear control, matured in the 1980s and 1990s, to be extended from ODEs to PDEs, allowing feedback synthesis for systems that are uncertain, nonlinear, and infinite-dimensional. The PDE backstepping literature has since grown to hundreds of papers and nearly a dozen books. This survey aims to facilitate the entry into this thriving area of overwhelming size and topical diversity. Designs of controllers and observers, for parabolic, hyperbolic, and other classes of PDEs, in one or more dimensions, with nonlinear, adaptive, sampled-data, and event-triggered extensions, are covered in the survey. The lifeblood of control are technology and physics. The survey places a particular emphasis on applications that have motivated the development of the theory and which have benefited from the theory and designs: flows, flexible structures, materials, thermal and chemically reacting dynamics, energy (from oil drilling to batteries and magnetic confinement fusion), and vehicles
Approximating the Uniform Value in Hidden Stochastic Games with Doeblin Conditions
No full textIn \emph{zero-sum two-player hidden stochastic games}, players observe partial information about the state. We address: the existence of the \emph{uniform value}, i.e., a limiting average payoff that both players can guarantee for sufficiently long durations, and the existence of an algorithm to approximate it. Previous work shows that, in the general case, the uniform value may fail to exist, and, even when it does, there need not exist an algorithm to compute or approximate it. Therefore, we consider the \emph{Doeblin condition} in hidden stochastic games, requiring that, after a sufficiently long time, the posterior beliefs have a uniformly positive probability of resetting to one of finitely many neighborhoods in the belief space. We prove the existence of the uniform value and provide an algorithm to approximate it. We identify sufficient conditions, namely \emph{ergodicity} in the blind setting (when the signal is uninformative) and \emph{primitivity} in the hidden setting (when there are multiple signals). Moreover, we show that, in the hidden setting, ergodicity does not guarantee the Doeblin condition. Our results are new even for the one-player setting, i.e., partially observable Markov decision processes
The Role of Commitment in Optimal Stopping
No full textWe investigate the role of commitment in optimal stopping by studying all the variants between Prophet Inequality (PI) and Pandora's Box (PB). Both problems deal with a set of variables drawn from known distributions. In PI the gambler observes an adversarial order of these variables with the goal of selecting one that maximizes the expected value against a prophet who knows the exact values realized. The gambler has to irrevocably decide at each step whether to select the value or discard it (commitment). On the other hand, in PB the gambler selects the order of inspecting the variables and for each pays an observation cost to see the actual value realized, aiming to choose one to maximize the net cost of the value chosen minus the observation cost paid. The gambler in PB can return and select any variable already seen (no commitment). For all the variants between these problems that arise by changing parameters such as (1) commitment (2) observation cost (3) order selection, we concisely summarize the known results and fill the gaps of variants not yet studied. We also uncover connections to Ski-Rental, a classic online algorithm problem
Sexing chicken embryos by real-time PCR using primers for the KCMF gene located on the W chromosome
No full textInternational audienceWith the recent publication of several European decrees prohibiting the culling of male chicks of laying breeds, the development of in-ovo sexing methods has become one of the priorities of the laying hen production industry. Regardless of the in-ovo sexing methods used, whether imaging approaches or quantification of specific compounds in embryo-derived samples, the prerequisite for accurate and sensitive in-ovo sexing methods is to establish a correlation between the egg picture and the sex of the embryo. It is therefore essential to know the sex of the embryo and have protocols that are easy to handle and implement, while allowing the analyses of hundreds of samples from a wide variety of tissues and chicken breeds. Among these protocols, real-time polymerase chain reaction using lysed samples containing DNA is likely to be of major interest. A few articles using specific primers, different types of chicken samples and breeds have been published, all with advantages and limitations. Here we describe a new protocol using a pair of primers designed to target a KCMF1-like gene located on the W sex chromosome, while the KCMF1 gene is located on the Z sex chromosome. This pair of primers was tested on four different chicken breeds at day 13 and 14 of development, using various tissues (liver, muscle, feather, heart, gonad, yolk sac, and chorioallantoic membrane) and fluids (blood and allantoic fluid). After 14 days of incubation, the comparison between the phenotype of male or female gonads and the real-time PCR results was 100% consistent, regardless of the breed. Thousands of samples in total have been analyzed by real-time PCR to validate the primers. The protocol is rapid and accurate and can be useful to sex 13 to 14-day old embryos to verify the sex predicted after evaluation of gonad dimorphism, or when the phenotypic sexing is inconclusive
Pea transcriptional and phytohormonal responses to adapted and non-adapted aphid biotypes at early stages of infestation
No full textInternational audiencePea (Pisum sativum L.), a major legume crop, is affected by various parasites including the pea aphid (Acyrthosiphon pisum Harris). The pea aphid is composed of multiple biotypes, each one being able to feed and reproduce on one or a few legume species. To understand the pea defense mechanisms to a pea adapted and a non-adapted A. pisum biotype, we studied the early molecular responses of four pea genotypes with contrasted levels of resistance, which are controlled primarily by the ApRVII locus. We found that major defense-related phytohormones and their derivatives in pea did not show clear response to aphid infestations. Transcriptomic analyses showed that the number of differentially expressed genes (DEGs) increased over time in pea genotypes infested with pea-adapted aphids, while significantly fewer DEGs were detected in genotypes infested with non-adapted aphids. The most resistant of the four investigated pea genotypes showed the fewest DEGs to both aphid biotypes. Aphid infestation of the three other pea genotypes commonly induced down-regulation of various pathways involved in fundamental biological processes. Comparison of the transcriptional data of pea genotypes identified candidate genes potentially involved in the aphid resistance conferred by ApRVII
Linking species traits and vulnerability indicators in European Odonata
No full textInternational audienceUnderstanding the mechanisms and commonalities driving species’ vulnerability is essential for prioritizing and guiding conservation efforts. Trait-based approaches offer a mechanistic foundation for generalizing species vulnerabilities within a taxonomic group. Here, we assess how the vulnerability of European Odonata is associated with their traits. Our aim was to (1) quantify the link between traits and vulnerability and (2) identify the most important traits in a multi-trait context. For 123 species, we linked 3 vulnerability indicators (Red List categories, distribution trends and areas of occupancy) to a dozen traits, using discriminant and redundancy analyses. We find that 48 to 64% of the variability in vulnerability indicators is explained by traits. The main traits related to vulnerability are habitat, voltinism and thermal preferences. More specifically, vulnerable species tend to associate with oligotrophic habitats or Mediterranean streams. They also tend to have longer life cycles, but this relationship is reversed for species with a small area of occupancy. Species vulnerable because of their decreasing distribution tend to have cold thermal preferences. Vulnerable species generally show a narrow thermal range (except for species vulnerable because of their decreasing distribution). Assessing species’ vulnerability is crucial to inform conservation: our trait-based approach provides clues regarding pressures responsible for species vulnerability, thus allowing to plan conservation action targeting groups of species sensitive to the same pressures, rather than focusing on individual species. Our method provides novel opportunities for predicting species’ vulnerability, and paves the way for building a multi-species conservation indicator for Odonata
Dormancy and reactivation of the seed and its microbiome: a holobiont perspective
No full textInternational audienceDesiccation-tolerant seeds provide an intriguing system for studying microbial dormancy, which includes reversible inactivation and reactivation in response to stress. Focusing on bacterial responses to desiccation and rehydration, we offer a holistic interpretation of dormancy and quiescence within the seed holobiont, highlighting both parallels and distinctions between microbes and their plant host. Based on pilot evidence, we propose that microbial dormancy supports persistence throughout the life cycle of desiccation-tolerant seeds. Transcriptomic analyses of seed-transmitted bacteria have identified genes implicated in inactivation and the viable-but-nonculturable state. Our analysis of Xanthomonas citri pv. fuscans illustrates this during seed maturation. However, the signals triggering microbial reactivation and the potential reciprocal interactions between seed dormancy and quiescence, and microbial dormancy, remain unknown. Elucidating this interplay within the seed holobiont could enhance plant growth and health either by promoting seed germination through microbial inoculation or by enabling early detection of seed-transmitted phytopathogens
Régulation du commerce international et enjeux de santé et d'environnement Des clauses miroir sont-elles pertinentes pour protéger le marché européen de l'usage de pesticides interdits dans l'UE ?
No full textInternational audienceDans son « Point de vue », Catherine Laroche donne à voir ce que l’on peut espérer et craindre des règles commerciales en ce qui concerne la prise en compte des effets sanitaires et environnementaux des échanges internationaux. Dans une sorte d’exercice de prospective fondé sur l’analyse de présents conflits commerciaux, l’autrice s’attache à saisir l’espace des possibles de futures clauses miroir qui se donneraient comme ambition de renforcer les objectifs du Pacte vert européen sans pour autant remettre en cause les accords internationaux multilatéraux mis en œuvre dans le cadre de l’OMC
Antioxidant functionalization of pullulan with ferulic acid using enzymatic catalysis
No full textInternational audienceAntioxidant polysaccharides were synthesized using an innovative, green, enzymatic reaction to catalyze thegrafting of ferulic acid (FA) onto pullulan (Pull). Several grades of Pull-FA with verified purity were successfullysynthesized, with maximum experimental grafting rates (GR) up to 8.8%, as determined by the Folin Ciocalteumethod. For the first time, the chemical structure of the grafts was proposed using 13C solid-state NMR andMALDI-TOF MS analyses, which proposed the putative grafting of a negatively charged, monodecarboxylated FAdimer (β-5). SEC/MALS/DRI/UV/visco analyses confirmed the grafting with a tendency towards intra- andintermolecular hydrophobic self-association, which depends on the grafting rate. The aggregative power of Pull-FAs in dilute medium as a function of the grafting rate and the pH of the medium was highlighted using the Nilered fluorescent probe and light scattering. In semi-dilute/concentrated media, intermolecular self-associationwas revealed by an increase in texture and a reversible physical gel behavior under favorable pH conditions.DPPH• analyses showed the antioxidant activity of Pull-FAs and confirmed the linear decrease in EC50 as afunction of grafting rate
Contrasted habitat selection among Eurasian curlew populations according to landscape heterogeneity and breeding stage
No full textInternational audienceSince the late 1970s, European landscapes have been severely degraded by the intensification of agricultural practices that replaced the historical mosaic of natural and agricultural environments with an increasingly uniform landscape. This homogenization of the mosaic structure has led to a depletion of available resources for farmland birds, resulting in a decline in their populations. This study aimed to quantify the relationships between spatial landscape heterogeneity and the spatio-temporal use of breeding habitats by Eurasian curlews (Numenius arquata) in contrasting agricultural landscapes. From 2020 to 2024, we tracked 64 adult curlews with global positioning system tags in 5 breeding sites with contrasting population dynamics in France (i.e., 2 declining, 2 increasing, and 1 stable). We assessed variations in home range size and habitat use according to breeding stage (i.e., pre-incubation, incubation, chick rearing, pre-migration), and assessed foraging habitat selection. Home ranges were small and did not differ in size among sites (mean ± SD = 97.4 ± 43.6 ha), although the</div