292 research outputs found

    Carbon stock increase during post-agricultural succession in central France: no change of the superficial soil stock and high variability within forest stages

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    Forest development following agricultural abandonment concerns extensive areas including the Massif Central region of France where this study was undertaken. This land-use and land-cover change is expected to have effects on biodiversity and ecosystem services, including an increase of carbon sequestration—a major concern in the face of climate change. Nevertheless, uncertainties about carbon stock changes during successions are remaining, especially as to the total stock and the contribution of the different carbon pools. Our work contributes to this field by studying carbon stocks in multiple plots of different successional stages. We measured and estimated carbon stocks in aboveground and belowground vegetation, deadwood, litter and superficial soil, and surveyed plant communities and plot conditions (slope, aspect, soil characteristics). The average total carbon stock increased along the succession from 70.60 at stage 0 to 314.19 tC ha−1 at stage 5. However, the total carbon stocks at the young forest stage (abandoned for 74 years maximum) and the older forest stage (forested for at least 74 years) were not significantly different, and probably reflected strong local heterogeneity in the older forest stage. An increase of the carbon stock was found in all pools, except the soil pool that did not vary significantly between the successional stages. The aboveground carbon stock was found strongly related to the woody species cover, especially the macrophanerophyte cover. This case study supports the view that the succession dynamics of former agricultural plots participates in carbon sequestration, sometimes with great local variations

    Patrons d'organisation des traits aériens et racinaires en prairies humides (liens avec la production primaire (quantité et qualité).)

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    Les prairies semi-naturelles constituent des espaces multifonctionnels susceptibles de rendre de nombreux services Ă  la sociĂ©tĂ©. Ce sont en particulier des agro-Ă©cosystĂšmes favorables Ă  l expression d une grande diversitĂ© floristique et faunistique permettant de concilier enjeux Ă©cologiques et agronomiques. Ce travail de thĂšse vise Ă  analyser (i) l'influence des facteurs environnementaux sur l'assemblage des communautĂ©s in situ et (ii) les relations entre la structure fonctionnelle des assemblages (i.e. valeurs de traits agrĂ©gĂ©es et diversitĂ© fonctionnelle) et leurs performances (i.e. production de biomasse et digestibilitĂ© de cette biomasse). Cette Ă©tude s'appuie sur des approches expĂ©rimentales et de terrain dans les prairies humides pĂąturĂ©es du Marais Poitevin. Nos rĂ©sultats montrent des rĂ©ponses trĂšs diffĂ©rentes des traits aĂ©riens et racinaires Ă©tudiĂ©s aux gradients de stress et de perturbation rencontrĂ©s dans ces prairies. Ils ont Ă©galement permis de mettre en Ă©vidence l'influence prĂ©pondĂ©rante des valeurs de traits agrĂ©gĂ©es sur la fourniture de services Ă©cosystĂ©miques (i.e. productivitĂ© et digestibilitĂ© du fourrage), en accord avec la "Biomass ratio hypothesis" Ă©noncĂ©e par Grime. L'influence du niveau de diversitĂ© fonctionnelle sur les services rendus par les assemblages varie selon le service considĂ©rĂ©. Contrairement aux rĂ©sultats attendus selon la "Diversity hypothesis" Ă©noncĂ©e par Tilman, le niveau de diversitĂ© fonctionnelle est liĂ© nĂ©gativement Ă  la productivitĂ© des assemblages. En revanche, un effet positif de la diversitĂ© fonctionnelle sur la digestibilitĂ© a Ă©tĂ© mis en Ă©vidence. Cette Ă©tude a par ailleurs permis de montrer un compromis entre la productivitĂ© des assemblages et la digestibilitĂ© de la biomasse produite dans ces prairies humides. Ce travail suggĂšre que des outils de diagnostics de la valeur fourragĂšre du couvert peuvent ĂȘtre construits sur la base de la structure fonctionnelle des assemblages, et ce avec un haut niveau de fiabilitĂ©. Il met Ă©galement en avant les bĂ©nĂ©fices agronomiques associĂ©s Ă  l'hĂ©tĂ©rogĂ©nĂ©itĂ© des couverts vĂ©gĂ©taux rencontrĂ©s dans ces prairies.Semi-natural grasslands form multifunctional areas susceptible to serve the society from many aspects. Indeed, they are agro-ecosystems that promote expression of a large floristic and faunistic diversity, which allows conciliating ecologic and agronomic issues. This PhD work aims at analysing (i) influence of environmental factors on natural communities' assembly rules and (ii) the relationships between the functional structure of assemblages (i.e. community weighted mean trait values and functional diversity) and their performances (i.e. biomass production and its digestibility). This study is based on both experimental and field approaches in the Marais Poitevin wet grasslands. Our results show that the studied aerial and root traits display a wide diversity of answers to stress gradients and disturbances encountered in these grasslands. Our results also highlighted the crucial influence of community weighted mean trait values on provision of ecosystem services (i.e. forage productivity and digestibility), in agreement with the Biomass ratio hypothesis set out by Grime. The influence of the functional diversity level on services provided by the assemblages differs depending on the service considered. Contrary to the results expected according to the Diversity hypothesis of Tilman, the functional diversity level is negatively correlated with the productivity of the assemblages. However, our study points to a positive feedback between functional diversity and digestibility. Furthermore, this study demonstrated the existence of trade-off between the productivity of assemblages and the digestibility of biomass produced in these wet grasslands. This work suggests that highly reliable tools can be established, based on the functional structure of assemblages, to evaluate the feeding value of a vegetal cover. This work finally illustrates the agronomic benefits associated with heterogeneous vegetal covers encountered in these grasslands.RENNES1-Bibl. Ă©lectronique (352382106) / SudocSudocFranceF

    Effects of reflux laryngitis on non-nutritive swallowing in newborn lambs

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    Reflux laryngitis in infants may be involved not only in laryngeal disorders, but also in disorders of cardiorespiratory control through its impact on laryngeal function. Our objective was to study the effect of reflux laryngitis on non-nutritive swallowing (NNS) and NNS-breathing coordination. Two groups of six newborn lambs, randomized into laryngitis and control groups, were surgically instrumented for recording states of alertness, swallowing and cardiorespiratory variables without sedation. A mild to moderate reflux laryngitis was induced in lambs from the experimental group. A significant decrease in the number of NNS bursts and apneas was observed in the laryngitis group in active sleep (p=0.03). In addition, lower heart and respiratory rates, as well as prolonged apnea duration (p<0.0001) were observed. No physiologically significant alterations in NNS-breathing coordination were observed in the laryngitis group. We conclude that a mild to moderate reflux laryngitis alters NNS burst frequency and autonomous control of cardiac activity and respiration in lambs

    Search for muon neutrinos from gamma-ray bursts with the ANTARES neutrino telescope using 2008 to 2011 data

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    9 pages, 8 figures; added Fig. 1 with effective area, updated Fig. 8 (b) according to arXiv:1204.4219 ; Références publication Astron Astrophys 559 (2013) A9International audienceAims. We search for muon neutrinos in coincidence with GRBs with the ANTARES neutrino detector using data from the end of 2007 to 2011. Methods. Expected neutrino fluxes were calculated for each burst individually. The most recent numerical calculations of the spectra using the NeuCosmA code were employed, which include Monte Carlo simulations of the full underlying photohadronic interaction processes. The discovery probability for a selection of 296 GRBs in the given period was optimised using an extended maximum-likelihood strategy. Results. No significant excess over background is found in the data, and 90% confidence level upper limits are placed on the total expected flux according to the model

    Sperm whale long-range echolocation sounds revealed by ANTARES, a deep-sea neutrino telescope

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    [EN] Despite dedicated research has been carried out to adequately map the distribution of the sperm whale in the Mediterranean Sea, unlike other regions of the world, the species population status is still presently uncertain. The analysis of two years of continuous acoustic data provided by the ANTARES neutrino telescope revealed the year-round presence of sperm whales in the Ligurian Sea, probably associated with the availability of cephalopods in the region. The presence of the Ligurian Sea sperm whales was demonstrated through the real-time analysis of audio data streamed from a cabled-to- shore deep-sea observatory that allowed the hourly tracking of their long-range echolocation behaviour on the Internet. Interestingly, the same acoustic analysis indicated that the occurrence of surface shipping noise would apparently not condition the foraging behaviour of the sperm whale in the area, since shipping noise was almost always present when sperm whales were acoustically detected. The continuous presence of the sperm whale in the region confirms the ecological value of the Ligurian sea and the importance of ANTARES to help monitoring its ecosystemsThe authors acknowledge the financial support of the funding agencies: Centre National de la Recherche Scientifique (CNRS), Commissariat a lenergie atomique et aux energies alternatives (CEA), la Commission Europeenne (FEDER fund and Marie Curie Program), Institut Universitaire de France (IUF), IdEx program and UnivEarthS Labex program at Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), Region Ile-de-France (DIM-ACAV), Region Alsace (contrat CPER), Region Provence-Alpes-Cote d'Azur, Departement du Var and Ville de La Seyne-sur-Mer, France; Bundesministerium fur Bildung und Forschung (BMBF), Germany; Istituto Nazionale di Fisica Nucleare (INFN), Italy; Stichting voor Fundamenteel Onderzoek der Materie (FOM), Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), the Netherlands; Council of the President of the Russian Federation for young scientists and leading scientific schools supporting grants, Russia; National Authority for Scientific Research (ANCS), Romania; Ministerio de Economia y Competitividad (MINECO), Prometeo and Grisolia programs of Generalitat Valenciana and MultiDark, Spain; Agence de l'Oriental and CNRST, Morocco. We also acknowledge the technical support of Ifremer, AIM and Foselev Marine for the sea operation and the CC-IN2P3 for the computing facilitiesAndre, M.; CaballĂ©, A.; Van Der Schaar, M.; Solsona, A.; HouĂ©gnigan, L.; Zaugg, S.; Sanchez, AM.... (2017). Sperm whale long-range echolocation sounds revealed by ANTARES, a deep-sea neutrino telescope. Scientific Reports. 7:1-12. https://doi.org/10.1038/srep45517S1127Aguilar, J. A. et al. ANTARES: the first undersea neutrino telescope. Nucl Inst and Met Phys Res A. 656, 11–38 (2011a).Aguilar, J. A. et al. AMADEUS - The Acoustic Neutrino Detection Test System of the ANTARES Deep-Sea Neutrino Telescope -. Nucl Inst and Met Phys Res A. 626–627, 128–143 (2011b).Ruhl, H. et al. Societal need for improved understanding of climate change, anthropogenic impacts, and geo-hazard warning drive development of ocean observatories in European Seas. Prog Oceanog. 91, 1–33 (2011).Tamburini, C. et al. 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II. 95, 160–181 (2013).SolĂ©, M. et al. Ultrastructural damage of Loligo vulgaris and Illex coindetii statocysts after low frequency sound exposure. PLoS One 8(10), e78825. doi: 10.1371/journal.pone.0078825 (2013).AndrĂ©, M. et al. Listening to the Deep: Live monitoring of ocean noise and cetacean acoustic signals. Mar Pollut Bull. 63, 18–26 (2011).Whitehead, H. Sperm whales: social evolution in the ocean(The University of Chicago Press, Chicaho, 2003).Mohl, B., Wahlberg, M., Madsen, P. T., Heerfordt, A. & Lund, A. The monopulsed nature of sperm whale clicks. J Acous Soc Am. 114, 1143–1154 (2003).AndrĂ©, M., Johansson, T., Delory, E. & van der Schaar, M. Foraging on squid: the sperm whale mid-range sonar. Jour Mar Biol Assoc. 87, 59–67 (2007).Madsen, P., Wahlberg, M. & MĂžhl, B. Male sperm whale (Physeter macrocephalus) acoustics in a high-latitude habitat: implications for echolocation and communication. 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    Detection chain and electronic readout of the QUBIC instrument

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    The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻Âč⁶ W/√Hz

    Detection chain and electronic readout of the QUBIC instrument

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    The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻Âč⁶ W/√Hz

    BLOOM: A 176B-Parameter Open-Access Multilingual Language Model

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    Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License

    Essai de restauration de roseliÚres en marais dulçaquicole

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    RĂ©habiliter un habitat sensible typique des zones humides favorable Ă  une espĂšce d’oiseau patrimoniale tout en dĂ©veloppant une filiĂšre Ă©conomique d’exploitation des roseaux font partie des objectifs fixĂ©s par l’opĂ©ration de restauration Ă©cologique des roseliĂšres des marais de Grande BriĂšre. En voici les premiers rĂ©sultats

    Concilier qualités agronomiques et environnementales des prairies

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