Geologic map of the Basque-Cantabrian Basin and a new tectonic interpretation of the Basque Arc     

B. Ábalos 《International Journal of Earth Sciences》2016,105(8):2327-2354

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An effective Lagrangian description of supernova-core bounce     

H. Rodrigues  S. B. Duarte  T. Kodama  V. d'Ávila 《Astrophysics and Space Science》1992,194(2):313-326

In standard hydrodynamical supernova computations many variables are needed to describe the time evolution of the stellar core. A numerical grid of points is usually constructed to attain the desirable accuracy. This fact limits the codes to run in the biggest and fastest computers. A new semi-analytical approach for the problem of the dynamical evolution of the collapse, bounce and explosion of a supernova core is proposed. The relevant coordinates of the dynamical problem are chosen to define an effective Lagrangian. The Lagrangian variables are the radii of the shells, seen now as collective coordinates, which describe the global aspects of the process. An effective Lagrangian with these properties for any number of shells is presented. The equations of motion are obtained from this Lagrangian and then integrated numerically. The potentiality of the method is exemplified for the extreme case in which only two shells are used to describe the stellar core. Even in this instance, it is possible to discuss the circumstances for the occurrence of supernova explosion.  相似文献   

Women in the History of Astronomy     

M. Álvarez Álvarez  Ángeles I. Díaz 《Astrophysics and Space Science》1998,263(1-4):401-404

We think about the History of Astronomy as the History of men. As the History of a few men: Ptolemy, Copernicus, Kepler, Newton,...- men who have changed our way of looking at the sky. But the History of Astronomy is more than that, it is the History of thousand of people whose daily work has allowed the development of knowledge and scientific theories at the time they lived. This, sometimes, "tedious work" permitted the big steps. Many of these people were women, as Theano who married Pythagoras and taught mathematics and astronomy in his school, Hypatia who managed the Library of Alexandria and wrote several astronomical treatises, Hildegard of Bingen who developed a theory on the origin and structure of the Universe in the 12^th century, or Sofie Brahe who, worked with her famous brother. And so many privileged women who after a long process of study, were able to develop their scientific interests in spite of been excluded from most of the educational installations and formal and informal groups of men scientist. Most of the works done by these women have been ignored, or wrongly attributed to men throughout History. It often happens that although they have been recognized as good scientists in their own times, women have been discredited by posterior historians who refused to believe that important women scientist ever existed. Here we intend to make a short summary on the lives of some of these women and their astronomical works. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Chemical Evolution in the Early Universe: Can Damp Lyα Systems Be Spiral Galaxies?     

Ángeles I. Díaz  Mercedes Mollá  Federico Ferrini 《Astrophysics and Space Science》1998,263(1-4):71-74

The distribution of element abundances with redshift in Damped Lyα (DLA) systems can be adequately reproduced by the same models reproducing the halo and disk components of the Milky Way Galaxy at different galactocentric distances. In this sense, DLA systems are well represented by normal spiral galaxies in their early evolutionary stages. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

A New Method to Determine the Derivatives of the Laplace Coefficients     

Áron Süli  Bálint Érdi  András Pál 《Celestial Mechanics and Dynamical Astronomy》2004,88(3):259-268

The determination of the secular variations of the orbital elements of objects in N-body systems is based on the literal development of the perturbing function. The development makes use of the Laplace coefficients and their derivatives. In this paper a new method is described for the analytical computation of the derivatives of the Laplace coefficients. It is an explicit formula in the sense that it only contains the Laplace coefficients and the parameter on which the Laplace coefficients depend. The advantage of this method is that it is unnecessary to calculate all the derivatives up to the desired order. It is enough to calculate the Laplace coefficients. Easy coding is a further benefit of the method and it provides more accurate numerical results. The paper describes in detail the application of the method through an example and gives comparison with former methods.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

Quality indices of groundwater for agricultural use in the region of Tierra Nueva,San Luis Potosi,Mexico     

José Alfredo Ramos-Leal  B. López-Álvarez  G. Santacruz-De León  O. Almanza-Tovar  J. Morán-Ramírez  D. A. Padilla-Reyes  Z. I. González-Acevedo 《Arabian Journal of Geosciences》2016,9(19):736

The paper evaluates the quality of groundwater for agricultural use in Tierra Nueva, San Luis Potosi, Mexico, where the agricultural productivity zone presents problems of salinity soil. Twenty groundwater samples and 11 soil samples at 2 depths at each point were collected and analyzed. In this type of water quality study, Wilcox classification diagram and the method of Salinity Laboratory United States for the quality of agricultural land were used. However, in some cases, these rankings do not reflect the actual condition, as in the case of Tierra Nueva, where the soil is classified as normal while water is classified at intermediate good. To analyze the real conditions of soil and water quality indicators of water for agricultural use risk of salinization, sodium adsorption ratio, adsorption ratio magnesium, permeability index, sodium percentage, soluble sodium percentage, residual sodium carbonate, and Kelly ratio were used. Sodicity rates including sodium adsorption ratio indicate no problem in soil extract. However, 25% of water samples are dangerous, with levels ranging from medium to high. For indexes of sodium percentage, residual sodium carbonate, and Kelly ratio, a distribution of classes ranging from questionable to inadequate was applied. Salinity levels show that effective salinity has good classification; potential salinity (PS) is conditional and therefore not recommended; and osmotic potential and electrical conductivity are classified as high in saline water, which is an increasingly important problem. The combination of different indices emphasized serious problems of salinity conditions, particularly sodicity.  相似文献   

Photoprotective role of inflorescence and UV-radiation effects on pollen viability of different freshwater plants     

Rafael M. Conde-Álvarez  Félix L. Figueroa  Elena Bañares-España  José M. Nieto-Caldera 《Aquatic Sciences - Research Across Boundaries》2008,70(1):57-64

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The Aguacaliente Fault,source of the Cartago 1910 destructive earthquake (Costa Rica)     

Jorge Alonso‐Henar  Walter Montero  José J. Martínez‐Díaz  José A. Álvarez‐Gómez  Juan M. Insua‐Arévalo  Wilfredo Rojas 《地学学报》2013,25(5):368-373

On 4 May 1910, the most destructive earthquake in the history of Costa Rica (Ms 6.4) destroyed the city of Cartago, a major city located in the Valle Central of Costa Rica. Using both palaeo‐seismological and morphotectonic analyses, we have found evidence that points to the Aguacaliente Fault (AF) as the source of this earthquake. This structure is a N100° E trending, strike‐slip fault situated to the south of Cartago and within a wide band of deformation. We excavated two trenches near Bermejo, south of Cartago. We found evidence of three surface ruptures within the last 1000 years on this fault. The age of the most recent rupture is consistent with the Cartago 1910 earthquake. The AF is a seismogenic source capable of producing large earthquakes (Mw 6.5–6.9) with an estimated recurrence interval of about 500 years.  相似文献   

The juxtaposition of eclogite and mid‐crustal rocks in the Orlica–Śnieżnik Dome,Bohemian Massif     

P. ŠTÍPSKÁ  F. CHOPIN  E. SKRZYPEK  K. SCHULMANN  P. PITRA  O. LEXA  J. E. MARTELAT  C. BOLLINGER  E. ŽÁČKOVÁ 《Journal of Metamorphic Geology》2012,30(2):213-234

Eclogite, felsic orthogneiss and garnet–staurolite metapelite occur in a 5 km long profile in the area of Mi?dzygórze in the Orlica–?nie?nik dome (Bohemian Massif). Petrographic observations and mineral equilibria modelling, in the context of detailed structural work, are used to document the close juxtaposition of high‐pressure and medium‐pressure rocks. The structural succession in all lithologies shows an early shallow‐dipping fabric, S1, that is folded by upright folds and overprinted by a heterogeneously developed subvertical foliation, S2. Late recumbent folds associated with a weak shallow‐dipping axial‐plane cleavage, S3, occur locally. The S1 fabric in the eclogite is defined by alternation of garnet‐rich (grs = 22–29 mol.%) and omphacite‐rich (jd = 33–36 mol.%) layers with oriented muscovite (Si = 3.26–3.31 p.f.u.) and accessory kyanite, zoisite, rutile and quartz, indicating conditions of ～19–22 kbar and ～700–750 °C. The assemblage in the retrograde S2 fabric is formed by amphibole, plagioclase, biotite and relict rutile surrounded by ilmenite and sphene that is compatible with decompression and cooling from ～9 kbar and ～730 °C to 5–6 kbar and 600–650 °C. The S3 fabric contains in addition domains with albite, chlorite, K‐feldspar and magnetite indicating cooling to greenschist facies conditions. The metapelites are composed of garnet, staurolite, muscovite, biotite, quartz, ilmenite and chlorite. Chemical zoning of garnet cores that contain straight ilmenite and staurolite inclusion trails oriented perpendicular to the external S2 fabric indicates prograde growth, from ～5 kbar and ～520 °C to ～7 kbar and ～610 °C, during the formation of the S1 fabric. Inclusion trails parallel with the S2 fabric at garnet and staurolite rims are interpreted to be a continuation of the prograde path to ～7.5 and ～630 °C in the S2 fabric. Matrix chlorite parallel to the S2 foliation indicates that the subvertical fabric was still active below 550 °C. The axial planar S2 fabrics developed during upright folding are associated with retrogression of the eclogite under amphibolite facies conditions, and with prograde evolution in the metapelites, associated with their juxtaposition. The shared part of the eclogite and metapelite P–T paths during the development of the subvertical fabric reflects their exhumation together.  相似文献   

Early Pleistocene palaeoenvironments at the time of the Homo antecessor settlement in the Gran Dolina cave (Atapuerca,Spain)     

HUGUES‐ALEXANDRE BLAIN  GLORIA CUENCA‐BESCÓS  FRANCESC BURJACHS  JUAN MANUEL LÓPEZ‐GARCÍA  IVÁN LOZANO‐FERNÁNDEZ  JORDI ROSELL 《第四纪科学杂志》2013,28(3):311-319

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