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51.
Joaquín Delgado Fernández 《Celestial Mechanics and Dynamical Astronomy》1988,44(3):299-307
In a recent paper [3], Lacomba and Llibre showed numerically the existence of two transversal ejection-collision orbits in Hill's problem for a valueC=5 of the Jacobian constant. This result can be used to prove the non-existence ofC
1-extendable regular integrals for Hill's problem. Here we give an analytic proof of the existence of four ejection-collision orbits which are transversal for large enough values ofC. 相似文献
52.
María Lina Berríos-Salas Margarita Guzmán-Vega José Fernández-Labra Manlio Maldini-Sánchez 《Astrophysics and Space Science》1989,162(2):205-209
This work presents the light curves for rotating spotted stars generated by a computational code developed by us. This code is based in a model of the system and its analytical solution. The work also present an analysis of the photometric curve variations with the changes in the model's parameters.As a first result we have simulated a temporal evolution of the light curve when the photospheric spot varies its size and position and we reproduced some observational light curves of the II Peg star.Work supported by Dirección de Investigación, Universidad de La Serena, Chile. 相似文献
53.
Summary Metamorphosed carbonatites and related skarn deposits, located in Fuerteventura Basal Complex, contain unusual Sr-rich minerals. Maximum SrO concentration in the following minerals are: calcite, 7.23wt%; apatite, 5.22wt%; epidote, 11.64wt%; clinozoisite, 1.25wt%; allanite, 5.63wt%; britholite, 4.11wt% and a Sr–Na aluminosilicate (probably stronalsite), 16.44wt% SrO. Calcite and apatite are chemically similar to those found in carbonatites and are therefore considered to be of igneous origin. Textural evidence indicates that the first skarn stage garnet+diopside+Sr–Na aluminosilicate formed as the result of chemical interaction between carbonatites and adjacent silicate rocks. The formation of Sr-bearing epidote/clinozoisite, allanite and britholite appears to be related to the release of Sr into the fluid phase from the breakdown of high temperature assemblages during the retrograde skarn stage. During the final evolution stages, further alteration of britholite by bastnäsite and törnebohmite took place. The occurrence of REE minerals shows that the fluids responsible for this metasomatism must also have transported significant quantities of REE. 相似文献
54.
On 25 April 1998 the tailings dam of the Aznalcóllar mine burst, a great quantity of pyrite waste sludge and acid water was spilled reaching the vicinity of the Doñana National Park. In surface and ground water samples taken a week after dam breaking, metals, trace elements and Pb isotopic ratios (206Pb/207Pb and 208Pb/206Pb) were analysed. In September 1998 a second sampling survey was carried out. The surface waters have a similar isotopic composition as the lead contained in the pyrite from the Aznalcóllar mine. The polluted groundwater of the Guadiamar aquifer also shows the influence of the mining origin of the lead. Lead isotope ratios (206Pb/207Pb and 208Pb/206Pb) in the groundwater of the Almonte-Marismas are very low and they differ clearly from the rest of groundwater samples. A further group of wells has a lead isotope composition intermediate between the Aznalcóllar mine and the atmospheric aerosols of the Iberian Peninsula. 相似文献
55.
56.
J. Angel Fernández Angela Ares Ana Rey-Asensio Alejo Carballeira Jesus R. Aboal 《Journal of Atmospheric Chemistry》2009,63(1):1-11
The effects of growth of autoirrigated, shaded transplants of Pseudoscleropodium purum on the quantification of tissue concentrations of Cd, Cu, Hg, V and Zn, were investigated in 4 exposure periods, each of
56 days, at 7 sampling sites (contaminated and uncontaminated). Concentrations of the elements in the basal portions of the
moss shoots were compared with the concentrations in the portions of the shoots that grew during the exposure period. Mercury
and V were present at lower concentrations in the new portions of the shoots than in the basal portions, whereas the opposite
was true for Cd, Cu and Zn. The magnitude of error introduced by growth was not negligible, and in some cases was higher than
40%, relative to the results obtained by analysis of the whole shoot. Devitalization of moss prior to its use as transplant
material is recommended to avoid growth of the plant during the exposure period. 相似文献
57.
C. Sigismondi D. W. Dunham K. Guhl S. Andersson H. Bode O. Canales P. Colona O. Farago M. Fernández-Ocaña A. Gabel M. Haupt C. Herold R. Nugent P. Oliva M. Patel C. Perello W. Rothe J. Rovira T. Schaefer C. Schnabel D. Schwartz A. Selva W. Strickling A. Tegtmeier C. Tegtmeier B. Thome W. H. Warren 《Solar physics》2009,258(2):191-202
In the annular or total eclipses of 3 October 2005, 29 March 2006, 22 September 2006, and 1 August 2008, observational campaigns
were organized to record the phenomenon of Baily’s beads. These campaigns were internationally coordinated through the International
Occultation Timing Association (IOTA) at both its American and European sections. From the stations in the northern and southern
zones of grazing eclipse, the eclipses have been recorded on video. Afterward, as many beads as possible have been identified
by analyzing the video data of each observing station. The atlas presented in this paper includes 598 data points, obtained
by 23 observers operating at 28 different observing stations. The atlas lists the geographic positions of the observing stations
and the observed time instants of disappearance or reappearance of beads, identified by an angle measured relative to the
Moon’s axis of rotation. The atlas will serve as a basis for determining the solar diameter.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
58.
59.
I. Díaz-Reviriego Á. Fernández-Llamazares P. L. Howard J. L. Molina V. Reyes-García 《社会与自然资源》2017,30(6):690-706
We employ social network analysis (SNA) to describe the structure of subsistence fishing social networks and to explore the relation between fishers’ emic perceptions of fishing expertise and their position in networks. Participant observation and quantitative methods were employed among the Tsimane’ Amerindians of the Bolivian Amazon. A multiple-regression quadratic assignment procedure was used to explore the extent to which gender, kinship, and age homophilies influence the formation of fishing networks. Logistic regressions were performed to determine the association between fishers’ expertise, their sociodemographic identities, and network centrality. We found that fishing networks are gendered and that there is a positive association between fishers’ expertise and centrality in networks, an association that is more striking for women than for men. We propose that a social network perspective broadens understanding of the relations that shape the intracultural distribution of fishing expertise, as well as natural resource access and use. 相似文献
60.
Acero Francisco Javier Fernández-Fernández María Isabel Carrasco Víctor Manuel Sánchez Parey Sylvie Hoang Thi Thu Huong Dacunha-Castelle Didier García José Agustín 《Theoretical and Applied Climatology》2018,133(1-2):605-617
Theoretical and Applied Climatology - Heat wave (HW) events are becoming more frequent, and they have important consequences because of the negative effects they can have not only on the human... 相似文献