Abstract We monitored leaf production in seedlings, trunkless juvenile, immature, and mature male and female plants of the dioecious palm, Lodoicea maldivica , and studied how internode length ...changed with trunk height. The fieldwork was conducted in closed forest on Praslin Island and degraded forest on Curieuse Island. Data on numbers of leaves produced and rates of leaf production were used to estimate plant age. On Praslin, the interval between successive leaves increased from 0.47/0.52 years in male/female plants to 4.2 years in seedlings, and on Curieuse from 0.41/0.49 to 2.3 years. Estimated leaf lifespan was 6.4–6.8 years in mature palms and much longer in seedlings and juveniles. On Praslin, internode length increased from the base of the trunk to a mean of 14 cm at leaf 21, before declining to 2.75 cm above leaf 100. Mean internode length of the smaller palms on Curieuse was 1.9 cm and varied little with height. Plants at the same development stage varied widely in age. On Praslin, median time to maturity was 77 (range: 32–209) and on Curieuse 83 (31–191) years. The tallest palms on Praslin (28.4 m trunk height) and Curieuse (8 m) were estimated at 442 and 232 years old, respectively. The ageing method was used to interpret height data of different populations. All showed a marked decline in regeneration in the 19th or early 20th centuries, probably caused by fires. We conclude that slow growth makes this species very vulnerable to disturbance, especially from fire.
L’inflammation chronique du tissu adipeux (TA) associée à l’obésité favorise le développement de l’insulinorésistance. Les vésicules extra-cellulaires (VEs) issues du tissu adipeux ont récemment été ...identifiées comme d’importants acteurs de la communication extracellulaire impliquée dans le contrôle de la sensibilité à l’insuline et plus globalement de l’homéostasie glucidique et énergétique. Le contenu de ces VEs (ARNs, protéines, lipides) de même que leur composition membranaire joue en effet un rôle biologique sur leurs cellules cibles.
Nous avons précédemment montré que la vitamine D (VD) limitait l’inflammation métabolique en diminuant l’expression intracellulaire de marqueurs inflammatoires comme les micro-ARN 155 (miR-155) ou miR-146a, dans différents modèles in vitro et in vivo. Ces miARNs pourraient être incorporés dans les VEs et par ce biais, moduler l’activité de cellules cibles. Néanmoins, les liens entre les micronutriments et la libération de ces miARNs vésiculés restent largement à être clarifiés.
Il a également été montré que la capture des VEs par leurs cellules cibles était assurée par des interactions spécifiques entre des protéines présentes à la surface des VEs (tétraspanines et intégrines) et des récepteurs membranaires de la cellule cible conduisant à la l’internalisation du contenu vésiculaire. Cependant, il n’y a actuellement pas de données rapportant l’effet des micronutriments sur le niveau d’expression membranaire de ces protéines vésiculaires dans un contexte inflammatoire.
Ainsi, nous avons émis l’hypothèse que la VD pourrait moduler la composition membranaire ainsi que le contenu en miARNs des VEs issues du TA.
Dans cette étude, nous avons utilisé des modèles murins et humains d’adipocytes incubés avec de la VD préalablement à un stress inflammatoire au Tumor Necrosis Factor α (TNFα) puis avons étudié le contenu en miARN dans les VEs par PCR quantitative. En parallèle, nous avons également investigué l’effet des différents traitements sur la composition protéique membranaire des VEs grâce à un approche originale en cytométrie en flux permettant de quantifier le nombre de protéines exprimées à la membrane des VEs (quantimétrie).
Nous avons constaté que l’inflammation augmentait l’expression de miR-155 et miR-146a intracellulaire mais également dans les VEs, tandis qu’une incubation à la VD réduisait cette expression dans les cellules et les VEs. Par les approches de quantimétrie, nous avons également observé que la VD et le TNFα modulaient l’expression de CD49e et CD61, deux intégrines connues pour être impliquées dans l’adhésion des vésicules aux cellules cibles.
Ces données suggèrent que la VD pourrait moduler le contenu en miRNA et la composition en protéines membranaires des VEs ce qui pourrait donc constituer une nouvelle voie d’action de la VD dans le contrôle de l’homéostasie glucidique et énergétique.
Context.
The Centaur (10199) Chariklo has the first ring system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow sizes and shapes ...to be determined with kilometre accuracy, and provide the characteristics of the occulting object and its vicinity.
Aims.
Using stellar occultations observed between 2017 and 2020, our aim is to constrain the physical parameters of Chariklo and its rings. We also determine the structure of the rings, and obtain precise astrometrical positions of Chariklo.
Methods.
We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the datasets, from which ingress and egress times, and the ring widths and opacity values were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo’s shape and ring structure.
Results.
We characterise Chariklo’s ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirm the detection of W-shaped structures within C1R and an evident variation in radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating a ring particle size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3
σ
), and its width variations may indicate an eccentricity higher than ~0.005. We fit a tri-axial shape to Chariklo’s detections over 11 occultations, and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8
−1.5
+1.4
, 135.2
−2.8
+1.4
, and 99.1
−2.7
+5.4
km. Ultimately, we provided seven astrometric positions at a milliarcsecond accuracy level, based on
Gaia
EDR3, and use it to improve Chariklo’s ephemeris.
Le vieillissement est associé avec une diminution de la concentration plasmatique en 25(OH)D. On suppose classiquement qu’une telle diminution âge-dépendant est lié en grande partie à une réduction ...du précurseur de la vitamine D (7-déhydrocholestérol) dans l’épiderme. Néanmoins, d’autres mécanismes âge-dépendant pourraient participer à cette diminution de la valeur plasmatique de la 25(OH)D et notamment la 25-hydroxylation hépatique, le stockage adipeux ou la clairance rénale.
Ainsi, nous avons étudier l’effet du vieillissement sur le métabolisme de la vitamine D dans les principaux organes impliqués dans son homéostasie.
Des souris C57BL/6JRJ jeunes (6 mois) ont été comparé à des souris âgées (23 mois). Nous avons déterminé le niveau circulant de la vitamine D et de la 25(OH)D, l’expression des gènes codant pour les acteurs majeurs de la 25-hydroxylation (Cyp2r1, Cyp27a1, Cyp2j6, Cyp3a11) dans le foie, l’expression des gènes codant pour les acteurs majeurs de la 1,25-hydroxylation (Cyp27b1) dans les reins et également l’expression des gènes codant pour des protéines de transport, les récepteurs, le captage et l’inactivation de la vitamine D (respectivement, Vdbp, Vdr, Mégaline, Cubiline, Cyp24a1, Cyp3a11) dans le foie et les reins. Nous avons également déterminé l’expression génique des gènes précédents dans le tissu adipeux blanc, le tissu majeur du stockage de la vitamine D.
Chez les souris âgées de 23 mois, nous observons une réduction du taux de 25(OH)D circulant mais aucune modification du taux circulant de D3 comparé aux souris âgées de 6 mois. L’expression génique de Cyp27a1, Cyp3a11, Cyp2j6 (avec une tendance à la diminution pour Cyp2r1) est diminué dans le foie chez les souris âgés, suggérant une diminution de la capacité hépatique de production de la 25(OH)D. L’expression génique de Cyp27b1 est augmentée dans les reins chez les souris âgés, qui est cohérente avec la diminution des valeurs plasmatiques de 25(OH)D. Enfin, nos résultats montrent une augmentation de l’expression génique de Cyp27a1, Cyp2j6 et Cyp27b1 dans le tissu adipeux blanc, suggérant une augmentation de la mise en réserve de la 25(OH)D.
Ces données suggèrent fortement que le métabolisme de la vitamine D est affecté au niveau transcriptionnel chez les souris âgées, en particulier dans le foie et le tissu adipeux. De telles altérations pourraient contribuer à réduire les niveaux circulant de 25(OH)D chez les personnes âgées.
•A simplified heat transfer model of turbochargers is developed.•Semi-empirical correlations are proposed.•Validation is performed on two different engines.•Engine simulation accuracy is improved ...particularly for temperatures.
Available turbocharger characterization maps are usually obtained on a gas stand where the turbine intake temperature is high, resulting in heat transfer affecting both the compressor and turbine. A correction is then mandatory to take into account heat transfer and calculate the real amount of work produced or consumed.
An experimental campaign is conducted to characterize heat transfer and friction losses on two different turbochargers. Then, semi-empirical correlations are developed minimizing the sum of square errors of a multiple regression to modelize these two phenomena. Compared to existing methodologies, these correlations minimize the requested input data: only the supplier maps are required whereas no additional test or calibration is needed.
The methodology to transform efficiencies and model heat transfer is presented. A gain of 10 % is observed on the confidence interval +/−3 °C on the compressor outlet temperature calculation (passing from 42.2 to 53 %), beside the turbine outlet temperature +/−10 °C interval is improved by around 20 %. These improvements are observed on two engine 1D models using two different turbochargers. The second engine's turbocharger is not involved in the establishment of the correlations and then demonstrates the good predictability of the proposed methodology.
We report the observation of two stellar occultations by Titan on 14 November 2003, using stations in the Indian Ocean, southern Africa, Spain, and northern and southern Americas. These occultations ...probed altitudes between ∼550 and 250 km (∼1 to 250 μbar) in Titan's upper stratosphere. The light curves reveal a sharp inversion layer near 515 ± 6 km altitude (1.5 μbar pressure level), where the temperature increases by 15 K in only 6 km. This layer is close to an inversion layer observed fourteen months later by the Huygens HASI instrument during the entry of the probe in Titan's atmosphere on 14 January 2005 Fulchignoni et al., 2005. Central flashes observed during the first occultation provide constraints on the zonal wind regime at 250 km, with a strong northern jet (∼200 m s−1) around the latitude 55°N, wind velocities of ∼150 m s−1 near the equator, and progressively weaker winds as more southern latitudes are probed. The haze distribution around Titan's limb at 250 km altitude is close to that predicted by the Global Circulation Model of Rannou et al. (2004) in the southern hemisphere, but a clearing north of 40°N is necessary to explain our data. This contrasts with Rannou et al.'s (2004) model, which predicts a very thick polar hood over Titan's northern polar regions. Simultaneous observations of the flashes at various wavelengths provide a dependence of τ ∝ λ−q, with q = 1.8 ± 0.5 between 0.51 and 2.2 μm for the tangential optical depth of the hazes at 250 km altitude.
The Centaur (10199) Chariklo has the first rings system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow the determination of ...sizes and shapes with kilometre accuracy and obtain characteristics of the occulting object and its vicinity. Using stellar occultations observed between 2017 and 2020, we aim at constraining Chariklo's and its rings physical parameters. We also determine the rings' structure, and obtain precise astrometrical positions of Chariklo. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the data sets, from which ingress and egress times, and rings' width and opacity were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and rings' structure. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirmed the detection of W-shaped structures within C1R and an evident variation of radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating ring particle's size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3-sigma), and its width variations may indicate an eccentricity higher than 0.005. We fit a tri-axial shape to Chariklo's detections over eleven occultations and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8, 135.2 and 99.1 km. Ultimately, we provided seven astrometric positions at a milliarcseconds accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris.
Global warming represents a major subject on all society levels including governments, economic actors and citizens. The textile industry is often considered a polluting activity. In this project, ...French textile manufacturers sought to quantify the carbon footprint (CF) of sold clothes and household linen using Life Cycle Assessment in France for the purpose of reducing it to meet the constraints of Paris Agreement by 2050. First, manufacturers calculated the carbon footprint of 17 clothes and household linen products and established alternative scenarios for four production routes. Secondly, they modeled the supply of the upstream sector through different countries. Based on imports of textile products, their calculated CF for one French person reaches 442 kg of CO2eq/year. Means of action to reduce this carbon footprint by a factor of 6 (74 kg of CO2eq/person/year for textiles) are calculated and are the following: installing the most energy-intensive production processes in a country with a low carbon electricity mix, avoiding unsold goods, implementing eco-design approaches and enhancing the value of end-of-life products with reuse or recycling. Therefore, CF for textiles per capita is reduced to 43 kg CO2eq/year which goes beyond the objectives of Paris Agreement and facilitates carbon neutrality in the textile sector. The first priority for reducing the French carbon footprint of clothes and household linen would be to locate textile production in countries with (i) low carbon electricity, (ii) to reduce unsold items, and (iii) to elaborate ecodesign of product including circular economy.
In this paper, we define two particular forms of non-termination, namely
loops
and
binary chains
, in an abstract framework that encompasses term rewriting and logic programming. The definition of ...loops relies on the notion of
compatibility
of binary relations. We also present a syntactic criterion for the detection of a special case of binary chains. Moreover, we describe our implementation NTI and compare its results at the Termination Competition 2023 with those of leading analyzers.
Coral reefs occur in nutrient-poor shallow waters, constitute biodiversity and productivity hotspots, and are threatened by anthropogenic disturbance. This Review provides an introduction to coral ...reef virology and emphasizes the links between viruses, coral mortality and reef ecosystem decline. We describe the distinctive benthic-associated and water-column- associated viromes that are unique to coral reefs, which have received less attention than viruses in open-ocean systems. We hypothesize that viruses of bacteria and eukaryotes dynamically interact with their hosts in the water column and with scleractinian (stony) corals to influence microbial community dynamics, coral bleaching and disease, and reef biogeochemical cycling. Last, we outline how marine viruses are an integral part of the reef system and suggest that the influence of viruses on reef function is an essential component of these globally important environments.
PDF
