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How Null Vector Performs in a Rational Bézier Curve with Mass Points
No full textInternational audienceThis article points out the kinematics in tracing a Bézier curve defined by control mass points. A mass point is a point with a non-positive weight, a non-negative weight or a vector with a null weight. For any Bézier curve, the speeds at endpoints can be modified at the same time for both endpoints. The use of a homographic parameter change allows us to choose any arc of the curve without changing the degree but not offer to change the speeds at both endpoints independently. The homographic parameter change performs weighted points with any non-null real number as weight and also vectors. The curve is thus called a rational Bézier curve with control mass points. In order to build independent stationary points at endpoints, a quadratic parameter change is required. Adding null vectors in the Bézier representation is also an answer. Null vectors are obtained when converting any power function in a rational Bézier curve and their inverse. The authors propose a new approach on placing null vectors in the representation of the rational Bézier curve. It allows us to break free from projective geometry where there is no null vector. The paper ends with some examples of known curves and some perspectives
The NLS4 equation of the NLS hierarchy and its rational solutions
No full textThis study concerns the research of rational solutions of the hierarchy of the nonlinear Schrödinger equation. In particular, we are interested in the equation of order 4. Rational solutions to the fourth equation of the NLS hierarchy are constructed and explicit expressions of these solutions are given for the first orders. These soltions depend on multi real parameters. We study the associated patterns of these solutions in the (x, t) plane according to the different values of parameters. This work allows to highlight the phenomenon of rogue waves as in the case of lower order equations such as the nonlinear Schrödinger equation, the mKdV equation or the Hirota equation.</div
Long-term effect of repeated application of pig slurry digestate on microbial communities in arable soils
No full textInternational audienceAnaerobic digestion represents an opportunity for converting organic waste (OW) into valuable products: renewable energy (biogas) and a fertilizer (digestate). However, the long-term effects of digestates on soil biota, especially microorganisms, need to be better documented to understand the impact of digestate on soil ecosystem functioning and resilience. This study assessed the cumulative effect of repeated pig slurry digestate applications on soil microbial communities over a decade, using an in-situ approach to compare digested feedstock with undigested feedstock and other fertilization treatments. Conducted from 2012 to 2022 at an experimental field site in France, the study involved plots with identical agricultural soil management practices, differing only in fertilization treatments: mineral fertilizer, three different OW (cattle manure, pig slurry, pig slurry digestate), and a control with no organic or mineral fertilizer input. Changes in soil microbial communities were analyzed through molecular microbial biomass and diversity assessments using high-throughput sequencing targeting 16S and 18S ribosomal RNA genes. DNA extraction and molecular analyses were performed on soil samples collected at the start of the trial in 2012 and subsequently in 2017 and 2022. The long-term effects of annual digestate application over a decade include a higher soil microbial diversity in digestate-treated plots than in pig slurry-treated plots, and changes in the soil's microbial community structure and taxonomic composition resembling those observed with mineral fertilizer. Differential abundance analysis at the phylum level revealed few significant differences between digestate- and mineral fertilizer-treated plots for both prokaryotic and fungal communities. Only plots amended with cattle manure exhibited higher soil organic carbon content. Agricultural practices, along with climatic and environmental fluctuations, can significantly influence the response of soil microbial communities, thereby buffering the effects of fertilization treatments. Further research is needed to better understand the effects on soil microbial communities, considering the interactions between repeated digestate applications, different pedological contexts, and agricultural practices
Experimental Evolution Induced by Maternal Post-copulatory Factors in Drosophila
No full textInternational audienceExperimental evolution is a powerful approach to study the mechanisms underlying the adaptation of selected characters under the conditions chosen in the laboratory. Drosophila melanogaster is a species frequently used to investigate the experimental evolution of characters, especially those related to reproduction. Recent intra-generational studies showed that cis-vaccenyl acetate (cVa), a sex pheromone transferred with bacteria on eggs by females either 1 day (D1) or 5 days (D5) after copulation, differentially affected the behavior and pheromone release in adult males emerging from these eggs. Here, we extended this finding to determine whether this alternative egg exposure repeated over many generations could affect a larger set of reproduction-related characters in both sexes. To test the repetitive effects of maternal D1 or D5 post-copulatory factors, we carried out an experimental selection procedure consisting of exposing eggs during 40 successive generations to D1 or D5 maternal post-copulatory factors. We compared cVa and cuticular pheromones, courtship and mating behaviors, and fecundity at different generations in flies of D1 and D5 lines. Based on findings obtained at earlier generations, we also determined survival, bacterial composition and gene expression in adults. Some of these complex traits significantly diverged between D1 and D5 lines indicating that maternal post-copulatory factors transmitted to eggs can influence adult life history traits
Determination of the Optimal Method for Measuring Malondialdehyde in Human Saliva
No full textInternational audienceWhile few methodological studies have been published on the salivary measurement of malondialdehyde (MDA), none have precisely detailed the analytical method. This work presents the development of an analytical method for MDA measurement in microvolumes of saliva samples from healthy individuals, using thiobarbituric acid derivatization and fluorescence reading of the formed compound. This method was progressively designed to meet specific constraints such as the limited sample volume available, cost-effectiveness of each assay, time required for analysis and costs. After studying the impact of various parameters, quantitative validation of this method was conducted using the accuracy profile. The study demonstrated that the fluorometric analysis method for salivary MDA accurately quantifies the concentration of this molecule within a validity range from 0.031 μM to 2.3 μM. Additionally, the accuracy profile allowed estimation of measurement uncertainty for each concentration level. It was determined that the calibration method using raw data was most appropriate as it introduced the least uncertainty in the obtained results
Die Entwicklung der ländlichen Gebiete Nordfrankreichs in der Spätantike : neue Siedlungssysteme, neue Siedlungstypen
No full textInternational audienc
Regional climate warming increases occurrence and intensity of winter wheat drought risk
No full textInternational audienceDuring the 1960–2021 period, France experienced two rapid increases in 2m air temperature, in 1987/1988 and 2014/2015. Between the periods 1960–1987 and 1988–2014, this induced significant differences in the mean state of the local water cycle climatic components. Evolving climate hazards linked to the water cycle led to water balance modifications, especially in winter bread wheat fields. This work aims to analyze the resulting changes in agro-climatic risk linked to drought after each abrupt warming. For each grid point of the Safran-Isba-Modcou (SIM) dataset and each year, daily values of Relative Extractible Water () under a wheat stress threshold of 40 % are cumulated to obtain a water stress index. For the first time, the modeling of water stress index distributions using Tweedie family distributions allows to disentangle modifications in frequency and intensity of drought events. These display various changes depending on the wheat production basin and the studied period. Overall, the mean water stress index increases in each production basin, with the Nord-Pas-de-Calais and Parisian production basins being particularly impacted by the 1987/1988 abrupt warming. Our results highlight that the modifications of climate hazards lead to harsher hydric stress events over main French wheat production basins. The probability of extreme drought events is rising strongly in several production basins. Changes in agro-climatic risk associated with drought are one of the main factors affecting crop growth cycle and development. As the probability to overcome risk threshold increases, yields may be significantly reduced, leading to increased economic losses. This is of major concern for the agricultural sector, including crop insurers, and underscores the urgent need for adaptation and prevention measures
“Vanishing Indians and Vanishing Landscapes in American Romantic Literature and Art”
No full textPrésentation faite au séminaire "Intermédialités Sensibles: Restitution(s) du Vivant” pour la séance « Paysages anthropologiques américains » au sein du Centre Interlangues – TIL, axe Image et Critique
