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31.
We present the Extended Hipparcos Compilation (XHIP), a database of all stars in the New Reduction of the Hipparcos Catalog extensively cross-referenced with data from a broad survey of presently available sources. The resulting collection uniquely assigns 116 096 spectral classifications, 46 392 radial velocities, and 18 549 homogenized iron abundances [Fe/H] to Hipparcos stars. Stellar classifications from SIMBAD, indications of multiplicity from CCDM or WDS, stellar ages from the Geneva-Copenhagen Survey III, supplemental photometry from 2MASS and SIMBAD, and identifications of exoplanet host stars are also included. Parameters for solar encounters and Galactic orbits are calculated for a kinematically complete subset. Kinetic bias is found to be minimal. Our compilation is available through the Centre de Données astronomiques de Strasbourg as Catalog V/137A. 相似文献
32.
Ever increasing pressures on tropical forests worldwide due to anthropogenic disturbances have greatly affected both above-and belowground functioning of these forests.While fine roots play major ecological roles in forests through assisting in nutrient and water uptake and returning elements to the soil environment,coarse roots play an important role in C sequestration.We studied changes in fine and coarse root biomass,production,turnover and carbon and nitrogen return to the soil in two regenerating forest stands(RFs)following stonemining that were 5 years(RF-5)and 15 years(RF-15)post-disturbance compared with a natural forest stand(NF)in Mizoram,North-east India.Fine(2mm)and coarse root(2-10 mm)biomass differed significantly among the forest stands and ranged from239(RF-5)to 415(NF)and 230(RF-5)to 436(NF)g m 2,respectively.Total root(fine+coarse)biomass increased during stand development but the proportion of very fine root(0.5 mm)to total root production decreased.Fine root biomass decreased with increasing soil depth.Fine and total root biomass showed strong seasonal correlations with soil moisture,more so than for rainfall and temperature,whereas these relationships were less clear for the coarse root biomass.The amount of N(25-55 kg ha~(-1))and C(1.9-3.6t ha~(-1))stored in root biomass increased with stand age with a corresponding increase in production and turnover of C and N to the soil.Disturbance to these tropical forests negatively affected root dynamics,influenced their spatiotemporal patterns,and reduced the production,amount and availability of nutrients returned to the soil along with a strong reduction in the root biomass carbon pool and sequestration in carbon residence time.We observed that root growth,especially fine roots,is dependent on abiotic variables,and plays a significant role in early stages of secondary succession by adding organic matter and nutrients through high turnover rates in these forests. 相似文献
33.
Dtissibe Francis Yongwa Ari Ado Adamou Abba Titouna Chafiq Thiare Ousmane Gueroui Abdelhak Mourad 《Natural Hazards》2020,104(2):1211-1237
Natural Hazards - Nowadays, floods have become the widest global environmental and economic hazard in many countries, causing huge loss of lives and materials damages. It is, therefore, necessary... 相似文献
34.
Jrme Gattacceca Francis M. Mccubbin Audrey Bouvier Jeffrey Grossman 《Meteoritics & planetary science》2020,55(2):460-462
Meteoritical Bulletin 107 contains 2714 meteorites including 16 falls (Aba Panu, Ablaketka, Andila, Gueltat Zemmour, Hamburg, Karimati, Mahbas Arraid, Mangui, Mazichuan, Mukundpura, Ozerki, Parauapebas, Renchen, San Pedro de Urabá, Sokoto, Tintigny), with 2226 ordinary chondrites, 168 HED achondrites, 132 carbonaceous chondrites (including 41 CM, 34 CV, 26 CO, 21 CK, 4 CR, 5 ungrouped), 43 ureilites, 30 iron meteorites (including 2 ungrouped), 29 lunar meteorites, 22 Martian meteorites, 16 primitive achondrites (including 3 brachinites), 12 Rumuruti chondrites, 9 enstatite chondrites, 7 ungrouped achondrites, 6 pallasites, 5 mesosiderites, 3 enstatite achondrites, 3 ungrouped chondrites, and 2 angrites. 1569 meteorites are from Antarctica, 835 from Africa, 206 from South America, 62 from Asia, 21 from North America, 11 from unknown locations, 8 from Europe (including one from Russia), and 1 from Oceania. 相似文献
35.
HD 115781 and HD 116204 (BL CVn and BM CVn) are shown to be RS CVn binaries with periods near 20 days. HD 115781 is double-lined;
the primary type is about K1III, while the secondary is probably a late-type subgiant. The masses of the two components are equal within observational error.
There is substantial photometric variability with a period half the orbital period; it is attributed to ellipsoidal variation.
HD 116204 is also of type K1III. It shows exceptionally strong Ca II H and K emission, together with an emission-line spectrum typical of RS CVn stars in
theIUE ultraviolet region, but Hα is an absorption line. The secondary star in the HD 116204 system has not been detected. The primary
shows photometric variations, presumably due to starspots, with a period 5 per cent longer than the orbital period. 相似文献
36.
Jérôme Gattacceca Francis M. McCubbin Jeffrey N. Grossman Devin L. Schrader Nancy L. Chabot Massimo D'Orazio Cyrena Goodrich Ansgar Greshake Juliane Gross Katherine Helen Joy Mutsumi Komatsu Bingkui Miao 《Meteoritics & planetary science》2023,58(6):901-904
Meteoritical Bulletin 111 contains the 3094 meteorites approved by the Nomenclature Committee of the Meteoritical Society in 2022. It includes 11 falls (Antonin, Botohilitano, Cranfield, Golden, Great Salt Lake, Longde, Msied, Ponggo, Qiquanhu, Tiglit, Traspena), with 2533 ordinary chondrites, 165 HED, 123 carbonaceous chondrites (including 4 ungrouped), 82 lunar meteorites, 28 Rumuruti chondrites, 27 iron meteorites, 23 ureilites, 22 mesosiderites, 22 Martian meteorites, 21 primitive achondrites (one ungrouped), 17 ungrouped achondrites, 13 pallasites, 7 enstatite achondrites, 6 enstatite chondrites, and 5 angrites. Of the meteorites classified in 2022, 1787 were from Antarctica, 1078 from Africa, 180 from South America, 34 from Asia, 6 from North America, 4 from Europe, and 1 from Oceania. 相似文献
37.
In contrast to earth, the atmosphere of the moon is exceedingly tenuous and appears to consist mainly of noble gases. The solar wind impinges on the lunar surface, supplying detectable amounts of helium, neon and 36Ar. Influxes of solar wind protons and carbon and nitrogen ions are significant, but atmospheric gases containing these elements have not been positively identified. Radiogenic 40Ar and 222Rn produced within the moon have been detected. The present rate of effusion of argon from the moon accounts for about 0.4% of the total production of 40Ar due to decay of 40K if the average abundance of potassium in the moon is 1000 ppm. Lack of weathering processes in the regolith suggests that most of the atmospheric 40Ar originates deep in the lunar interior, perhaps in a partially molten core. If so, other gases may be vented along with the argon. 相似文献
38.
David C. Little Simon R. BushBen Belton Nguyen Thanh PhuongJames A. Young Francis J. Murray 《Marine Policy》2012,36(3):738-745
Rapid growth in production of the farmed Vietnamese whitefish pangasius and its trade with the European Union has provoked criticism of the fish's environmental, social and safety credentials by actors including WWF and Members of the European Parliament and associated negative media coverage. This paper reviews the range of claims communicated about pangasius (identified as a form of mass mediated risk governance), in light of scientific evidence and analysis of data from the EU's Rapid Alert System for Food and Feeds food safety notification system for imported seafood. This analysis shows pangasius to be generally safe, environmentally benign and beneficial for actors along the international value chains that characterise the trade. The case is made that increasingly politicised debates in Europe around risk and uncertainty are potentially counterproductive for EU seafood security and European aquaculture industry, and that the trade in pangasius can contribute to sustainable seafood consumption in a number of ways. Transparent evidence-based assessment and systems for communicating complex issues of risk for products such as pangasius are required in order to support continuance of fair and mutually beneficial trade. 相似文献
39.
Joseph L. HARRIS Louis J. SCHWARZ William M. D'ANGELO Francis J. FLANAGAN 《Geostandards and Geoanalytical Research》1981,5(2):125-128
Additional data for gabbro, GOG-1, were determined by instrumental-neutron-activation analysis, atomic-absorption spectrometry, and semi-quantitative spectrographic analysis. F ratios calculated in the analysis of variance for 26 sets of data for elements determined by the three methods were not significant, and hence the elements are distributed homogeneously among the bottles. The agreement between our data and the averages previously published ranges from very good to poor. More analytical data are necessary to establish reliable estimates of the concentrations of elements in GOG-1 and in two other gabbros so that three gabbros may be available to geochemists for use as standards. 相似文献
40.
GeoJournal - Inspite of step-up efforts at controlling flood hazards in Third World cities, the frequency and magnitude of the flood problem have more than doubled in recent years. A survey of the... 相似文献