270 research outputs found

    First report of Brenneria goodwinii, Gibbsiella quercinecans and Rahnella victoriana in declining oaks in France

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    Acute Oak Decline, Quercus petraea, Quercus robur Acute Oak Decline (AOD) is mediated by abiotic factors (temperature and precipitation) and triggered by insects (mainly the bark-boring beetle Agrilus biguttatus) and a complex of bacterial species (mainly Bren-neria goodwinii, Gibbsiella quercinecans and Rahnella victoriana) (Denman et al., 2017; Doonan et al., 2020). Given the extent of oak dieback and the prevalence of A. biguttatus in France (Saintonge & Goudet, 2020; SallĂ© et al., 2022), a preliminary study was done in five French forests to assess the prevalence of AOD symptoms (bleeding cortical lesions on the trunk associated with insect emergence holes and dieback) and to determine the bacteria associated with those symptoms. The mean prevalence of AOD symptoms was estimated at 37% arround 20 trees assessed in each of the five forests. Bark samples and, when possible, exudates were taken from lesions associated with insect emergence holes and/or cracks (Fig. 1). Bacterial isolations were made from 43 bark samples and 11 exudate samples by plating on three agar media (Luria, Gifu Anaerobic and Eosin Methylene Blue) and incubated at 22 ‱ C for one to five days. Bacterial strains were identified by high-resolution melting (Brady et al., 2016) or 16S rRNA sequencing (Denman et al., 2016). The sequenced strains had 100% identity with sequences of reference strains (GenBank Accession Nos. CP014137.1, CP014136.1 and NR_146847.1). The percentage of trees infected with G. quercinecans, B. goodwinii and R. victoriana was 21, 16 and 12, respectively. These AOD-associated bacteria were detected with a higher success rate in exudates (81%) than in bark (25%). Gibbsiella quercinecans and B. good-This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited

    Bioenergy production and sustainable development: science base for policymaking remains limited

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    The possibility of using bioenergy as a climate change mitigation measure has sparked a discussion of whether and how bioenergy production contributes to sustainable development. We undertook a systematic review of the scientific literature to illuminate this relationship and found a limited scientific basis for policymaking. Our results indicate that knowledge on the sustainable development impacts of bioenergy production is concentrated in a few well-studied countries, focuses on environmental and economic impacts, and mostly relates to dedicated agricultural biomass plantations. The scope and methodological approaches in studies differ widely and only a small share of the studies sufficiently reports on context and/or baseline conditions, which makes it difficult to get a general understanding of the attribution of impacts. Nevertheless, we identified regional patterns of positive or negative impacts for all categories – environmental, economic, institutional, social and technological. In general, economic and technological impacts were more frequently reported as positive, while social and environmental impacts were more frequently reported as negative (with the exception of impacts on direct substitution of GHG emission from fossil fuel). More focused and transparent research is needed to validate these patterns and develop a strong science underpinning for establishing policies and governance agreements that prevent/mitigate negative and promote positive impacts from bioenergy production

    Cognitive impairment induced by delta9-tetrahydrocannabinol occurs through heteromers between cannabinoid CB1 and serotonin 5-HT2A receptors

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    Delta-9-tetrahydrocannabinol (THC), the main psychoactive compound of marijuana, induces numerous undesirable effects, including memory impairments, anxiety, and dependence. Conversely, THC also has potentially therapeutic effects, including analgesia, muscle relaxation, and neuroprotection. However, the mechanisms that dissociate these responses are still not known. Using mice lacking the serotonin receptor 5-HT2A, we revealed that the analgesic and amnesic effects of THC are independent of each other: while amnesia induced by THC disappears in the mutant mice, THC can still promote analgesia in these animals. In subsequent molecular studies, we showed that in specific brain regions involved in memory formation, the receptors for THC and the 5-HT2A receptors work together by physically interacting with each other. Experimentally interfering with this interaction prevented the memory deficits induced by THC, but not its analgesic properties. Our results highlight a novel mechanism by which the beneficial analgesic properties of THC can be dissociated from its cognitive side effects

    Operations of and Future Plans for the Pierre Auger Observatory

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    Technical reports on operations and features of the Pierre Auger Observatory, including ongoing and planned enhancements and the status of the future northern hemisphere portion of the Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200

    The Pierre Auger Observatory III: Other Astrophysical Observations

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    Astrophysical observations of ultra-high-energy cosmic rays with the Pierre Auger ObservatoryComment: Contributions to the 32nd International Cosmic Ray Conference, Beijing, China, August 201

    Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV

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    We describe the measurement of the depth of maximum, Xmax, of the longitudinal development of air showers induced by cosmic rays. Almost four thousand events above 10^18 eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106 +35/-21) g/cm^2/decade below 10^(18.24 +/- 0.05) eV and (24 +/- 3) g/cm^2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm^2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.Comment: Accepted for publication by PR

    Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory

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    The Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E>Eth=5.5×1019E>E_{th}=5.5\times 10^{19} eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at E>EthE>E_{th} are heavy nuclei with charge ZZ, the proton component of the sources should lead to excesses in the same regions at energies E/ZE/Z. We here report the lack of anisotropies in these directions at energies above Eth/ZE_{th}/Z (for illustrative values of Z=6, 13, 26Z=6,\ 13,\ 26). If the anisotropies above EthE_{th} are due to nuclei with charge ZZ, and under reasonable assumptions about the acceleration process, these observations imply stringent constraints on the allowed proton fraction at the lower energies

    Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

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    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius AA. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio

    Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

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    Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{6×10196\times 10^{19}eV}. The anisotropy was measured by the fraction of arrival directions that are less than 3.1∘3.1^\circ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron 12th12^{\rm th} catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is (38−6+7)(38^{+7}_{-6})%, compared with 2121% expected for isotropic cosmic rays. This is down from the early estimate of (69−13+11)(69^{+11}_{-13})%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201
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