227 research outputs found

    Kepler White Paper: Asteroseismology of Solar-Like Oscillators in a 2-Wheel Mission

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    We comment on the potential for continuing asteroseismology of solar-type and red-giant stars in a 2-wheel Kepler Mission. Our main conclusion is that by targeting stars in the ecliptic it should be possible to perform high-quality asteroseismology, as long as favorable scenarios for 2-wheel pointing performance are met. Targeting the ecliptic would potentially facilitate unique science that was not possible in the nominal Mission, notably from the study of clusters that are significantly brighter than those in the Kepler field. Our conclusions are based on predictions of 2-wheel observations made by a space photometry simulator, with information provided by the Kepler Project used as input to describe the degraded pointing scenarios. We find that elevated levels of frequency-dependent noise, consistent with the above scenarios, would have a significant negative impact on our ability to continue asteroseismic studies of solar-like oscillators in the Kepler field. However, the situation may be much more optimistic for observations in the ecliptic, provided that pointing resets of the spacecraft during regular desaturations of the two functioning reaction wheels are accurate at the < 1 arcsec level. This would make it possible to apply a post-hoc analysis that would recover most of the lost photometric precision. Without this post-hoc correction---and the accurate re-pointing it requires---the performance would probably be as poor as in the Kepler-field case. Critical to our conclusions for both fields is the assumed level of pointing noise (in the short-term jitter and the longer-term drift). We suggest that further tests will be needed to clarify our results once more detail and data on the expected pointing performance becomes available, and we offer our assistance in this work.Comment: NASA Kepler Mission White Paper; 10 pages, 2 figure

    Long-term follow-up after endoscopic resection for superficial esophageal squamous cell carcinoma: a multicenter Western studyAbstract

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    Background Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are the first-line treatments for superficial esophageal squamous cell carcinoma (SCC). This study aimed to compare long-term clinical outcome and oncological clearance between EMR and ESD for the treatment of superficial esophageal SCC. Methods We conducted a retrospective multicenter study in five French tertiary care hospitals. Patients treated by EMR or ESD for histologically proven superficial esophageal SCC were included consecutively. Results Resection was performed for 148 tumors (80 EMR, 68 ESD) in 132 patients. The curative resection rate was 21.3 % in the EMR group and 73.5 % in the ESD group (P &lt; 0.001). The recurrence rate was 23.7 % in the EMR group and 2.9 % in the ESD group (P = 0.002). The 5-year recurrence-free survival rate was 73.4 % in the EMR group and 95.2 % in the ESD group (P = 0.002). Independent factors for cancer recurrence were resection by EMR (hazard ratio [HR] 16.89, P = 0.01), tumor infiltration depth ≥ m3 (HR 3.28, P = 0.02), no complementary treatment by chemoradiotherapy (HR 7.04, P = 0.04), and no curative resection (HR 11.75, P = 0.01). Risk of metastasis strongly increased in patients with tumor infiltration depth ≥ m3, and without complementary chemoradiotherapy (P = 0.02). Conclusion Endoscopic resection of superficial esophageal SCC was safe and efficient. Because it was associated with an increased recurrence-free survival rate, ESD should be preferred over EMR. For tumors with infiltration depths ≥ m3, chemoradiotherapy reduced the risk of nodal or distal metastasis

    Ralstonia syzygii, the Blood Disease Bacterium and Some Asian R. solanacearum Strains Form a Single Genomic Species Despite Divergent Lifestyles

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    The Ralstonia solanacearum species complex includes R. solanacearum, R. syzygii, and the Blood Disease Bacterium (BDB). All colonize plant xylem vessels and cause wilt diseases, but with significant biological differences. R. solanacearum is a soilborne bacterium that infects the roots of a broad range of plants. R. syzygii causes Sumatra disease of clove trees and is actively transmitted by cercopoid insects. BDB is also pathogenic to a single host, banana, and is transmitted by pollinating insects. Sequencing and DNA-DNA hybridization studies indicated that despite their phenotypic differences, these three plant pathogens are actually very closely related, falling into the Phylotype IV subgroup of the R. solanacearum species complex. To better understand the relationships among these bacteria, we sequenced and annotated the genomes of R. syzygii strain R24 and BDB strain R229. These genomes were compared to strain PSI07, a closely related Phylotype IV tomato isolate of R. solanacearum, and to five additional R. solanacearum genomes. Whole-genome comparisons confirmed previous phylogenetic results: the three phylotype IV strains share more and larger syntenic regions with each other than with other R. solanacearum strains. Furthermore, the genetic distances between strains, assessed by an in-silico equivalent of DNA-DNA hybridization, unambiguously showed that phylotype IV strains of BDB, R. syzygii and R. solanacearum form one genomic species. Based on these comprehensive data we propose a revision of the taxonomy of the R. solanacearum species complex. The BDB and R. syzygii genomes encoded no obvious unique metabolic capacities and contained no evidence of horizontal gene transfer from bacteria occupying similar niches. Genes specific to R. syzygii and BDB were almost all of unknown function or extrachromosomal origin. Thus, the pathogenic life-styles of these organisms are more probably due to ecological adaptation and genomic convergence during vertical evolution than to the acquisition of DNA by horizontal transfer

    Climate control of terrestrial carbon exchange across biomes and continents

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    Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various ecosystems over six continents with a total of 559 site-years. We find that NEE observed at eddy covariance sites is (1) a strong function of mean annual temperature at mid- and high-latitudes, (2) a strong function of dryness at mid- and low-latitudes, and (3) a function of both temperature and dryness around the mid-latitudinal belt (45°N). The sensitivity of NEE to mean annual temperature breaks down at ∼16 ®C (a threshold value of mean annual temperature), above which no further increase of CO,.2uptake with temperature was observed and dryness influence overrules temperature influence. © 2010 lOP Publishing Ltd

    Reference procedures for the measurement of gaseous emissions from livestock houses and stores of animal manure.

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    In the ten years before the EMILI 2012 symposium, gaseous losses from animal farms became increasingly important in the m edia. The paradox of this tendency was the great number of publications, scientific or not, even though the emissions of most animal farms had never been measured. Therefor e, the development of reference tools to measure greenhouse gas and ammonia emissio ns was important. Such tools allow recognition and remuneration of the best pract ices and equipment. Accordingly, ADEME funded an international project associating several research and development organizations involved with the animal production chain. The project proposed an initial set of 18 procedures to measure ammonia and greenho use gas emissions from animal houses and manure stores. These were adapted to the diversity of animal farms found throughout the world. Some methods were compared duri ng a ?building? and a ?liquid manure? experiment. Results showed a high difference among methods (ca. 80%), much higher than the estimated uncertainty. Associat ing independent emission measurements, together with a mass balance of the system, is necessary for the reliability of further results. However, previously published references lack uncertainty estimates of measurements that conform to GUM 2008. In the coming years, this is one of the major concerns for measuring emission factor s. Uncertainty estimates should depend on the measurand (temporal: hourly, per batch, yearly; spatial: animal, house, national) and include the uncertainties associated with system representativity and temporal interpolation.Edited by Mélynda Hassouna and Nadine Guingand

    Sources and Sinks of Greenhouse Gases from European Grasslands and Mitigation Options: The ‘GreenGrass’ Project

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    Adapting the management of grasslands may be used to enhance carbon sequestration into soil, but could also increase N2O and CH4 emissions. In support of the European post-Kyoto policy, the European \u27GreenGrass\u27 project (EC FP5, EVK2-CT2001-00105) has three main objectives: i) to reduce the large uncertainties concerning the estimates of CO2, N2O and CH4 fluxes to and from grassland plots under different climatic conditions and assess their global warming potential, ii) to measure net greenhouse gas (GHG) fluxes for different management which reflect potential mitigation options, iii) to construct a model of the controlling processes to quantify the net fluxes and to evaluate mitigation scenarios by up-scaling to a European level

    Natural history of SLC11 genes in vertebrates: tales from the fish world

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    <p>Abstract</p> <p>Background</p> <p>The <it>SLC11A1/Nramp1 </it>and <it>SLC11A2/Nramp2 </it>genes belong to the <it>SLC11/Nramp </it>family of transmembrane divalent metal transporters, with <it>SLC11A1 </it>being associated with resistance to pathogens and <it>SLC11A2 </it>involved in intestinal iron uptake and transferrin-bound iron transport. Both members of the <it>SLC11 </it>gene family have been clearly identified in tetrapods; however <it>SLC11A1 </it>has never been documented in teleost fish and is believed to have been lost in this lineage during early vertebrate evolution. In the present work we characterized the <it>SLC11 </it>genes in teleosts and evaluated if the roles attributed to mammalian <it>SLC11 </it>genes are assured by other fish specific <it>SLC11 </it>gene members.</p> <p>Results</p> <p>Two different <it>SLC11 </it>genes were isolated in the European sea bass (<it>Dicentrarchus. labrax</it>), and named <it>slc11a2-α </it>and <it>slc11a2-β</it>, since both were found to be evolutionary closer to tetrapods <it>SLC11A2</it>, through phylogenetic analysis and comparative genomics. Induction of <it>slc11a2-α </it>and <it>slc11a2-β </it>in sea bass, upon iron modulation or exposure to <it>Photobacterium damselae </it>spp. <it>piscicida</it>, was evaluated in <it>in vivo </it>or <it>in vitro </it>experimental models. Overall, <it>slc11a2-α </it>was found to respond only to iron deficiency in the intestine, whereas <it>slc11a2-β </it>was found to respond to iron overload and bacterial infection in several tissues and also in the leukocytes.</p> <p>Conclusions</p> <p>Our data suggests that despite the absence of <it>slc11a1</it>, its functions have been undertaken by one of the <it>slc11a2 </it>duplicated paralogs in teleost fish in a case of synfunctionalization, being involved in both iron metabolism and response to bacterial infection. This study provides, to our knowledge, the first example of this type of sub-functionalization in iron metabolism genes, illustrating how conserving the various functions of the SLC11 gene family is of crucial evolutionary importance.</p
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