Dwarf elliptical galaxies     

Henry C. Ferguson  Bruno Binggeli 《Astronomy and Astrophysics Review》1994,6(1-2):67-122

Dwarf elliptical (dE) galaxies, with blue absolute magnitudes typically fainter than _MB =?16, are the most numerous type of galaxy in the nearby universe. Tremendous advances have been made over the past several years in delineating the properties of both Local Group satellite dE's and the large dE populations of nearby clusters. We review some of these advances, with particular attention to how well currently available data can constrain

1. models for the formation of dE's
2. the physical and evolutionary connections between different types of galaxies (nucleated and nonnucleated dE's, compact E's, irregulars, and blue compact dwarfs) that overlap in the same portion of the mass-spectrum of galaxies
3. the contribution of dE's to the galaxy luminosity functions in clusters and the field
4. the star-forming histories of dE's and their possible contribution to faint galaxy counts, and
5. the clustering properties of dE's.

In addressing these issues, we highlight the extent to which selection effects temper these constraints, and outline areas where new data would be particularly valuable.  相似文献   

An extended investigation of Helios 1 and 2 observations: The interplanetary magnetic field between 0.3 and 1 AU     

F. Mariani  U. Villante  R. Bruno  B. Bavassano  N. F. Ness 《Solar physics》1979,63(2):411-421

Helios-1 and 2 spacecraft allowed a detailed investigation of the radial dependence of the interplanetary magnetic field components between 0.3 and 1 AU. The behaviour of the radial component B _ris in a very good agreement with Parker's model (B _r r ^-2) and the azimuthal component B also shows a radial dependence which is close to theoretical predictions (B r ^-1). Experimental results for the normal component B and for the field magnitude B are consistent with those from previous investigations. The relative amplitude of the directional fluctuations with periods less than 12 hr is essentially independent of heliocentric distance, while their power decreases approximately as r ^–3 without any appreciable difference between higher and lower velocity regimes.Also at Laboratorio Plasma nello Spazio, CNR, Frascati.  相似文献   

On periodic flybys of the moon   总被引：1，自引：1，他引：0  

A. D. Bruno 《Celestial Mechanics and Dynamical Astronomy》1981,24(3):255-268

This paper considers the plane circular restricted three-body problem for small . Symmetric periodic solutions of the second species (passing near the body of mass ) and their distance from the center of the body of mass are studied by constructing perturbations of arc-solutions (solutions with consecutive collisions) existing for =0. Orbits which also pass near the body of mass 1- are studied in detail. The results are applied to finding periodic orbits in the Earth-Moon system and in the Sun-Jupiter system.Russian version: Preprint No. 91 (1978) of Inst. Appl. Math.; present English translation was made by L. M. Perko and W. C. Schulz (February 1979).  相似文献   

Enregistrement de la variabilité hydroclimatique au cours des 6500 dernières années sur le littoral de Cabo Frio (Rio de Janeiro,Brésil)     

Bérengère Laslandes  Florence Sylvestre  Abdelfettah Sifeddine  Bruno Turcq  Ana Luiza S. Albuquerque  Jorge Abrão 《Comptes Rendus Geoscience》2006,338(10):667-675

This study concerns a core collected in Brejo do Espinho's lagoon from Cabo Frio littoral (Brazil) submitted to dry influence of local upwelling controlled by north-east trade winds from the South Atlantic and particularly strengthened during El Niño events. Diatoms study supported by sedimentological and isotopic analyses shows dry phases infrequent before 4000 yr, a highly variable climatic phase between 3600 and 2900 yr and from 2400 yr onward a dryness enhancement. To cite this article: B. Laslandes et al., C. R. Geoscience 338 (2006).  相似文献   

Planation, bauxites and epeirogeny: One or two paleosurfaces on the West African margin?   总被引：3，自引：0，他引：3  

Dominique Chardon  Violaine Chevillotte  Anicet Beauvais  Georges Grandin  Bruno Boulang 《Geomorphology》2006,82(3-4):273-282

Mapping of lateritic bauxites over the West African rifted margin and analysis of the geomorphic properties of these bauxites, combined with available geological data lead to a discussion of the presence of either two Meso-Cenozoic planation surfaces or a single Eocene surface to account for the morphotectonic and paleoclimatic evolution of the Guinean landforms. At large scale, two stepped bauxitic levels are documented. Ongoing or episodic uplift following Gondwana breakup and Meso-Cenozoic climate change are proposed to have allowed the formation and abandonment of an Early mid-Cretaceous surface today preserved as the higher bauxitic level, and the setting of an Eocene planation surface bearing a second generation of bauxites, making the lower bauxitic level. The single Eocene surface hypothesis requires that Paleogene bauxitization preserved large pre-existing relief to explain two stepped bauxitic levels of the same age. The two-surface hypothesis is favored because it would explain rebauxitization of alluvial pebbles of bauxites under the lower lateritic level.  相似文献   

Comparative response analysis of conventional and innovative seismic protection strategies     

S. Bruno  C. Valente 《地震工程与结构动力学》2002,31(5):1067-1092

The paper presents a numerical investigation aimed at evaluating the improvements achievable through devices for passive seismic protection of buildings based on the use of shape memory alloys (SMA) in place of conventional steel or rubber devices. To get some generality in the results, different resisting reinforced concrete plane frames were analysed, either protected or not. ‘New’ and ‘existing’ buildings were considered depending on whether seismic provisions are adopted in the building design or not. Base isolation and energy dissipation were equally addressed for both conventional and innovative SMA‐based devices. Fragility analyses were performed using specific damage measures to account for comparisons among different damage types; the results were then used to estimate quantitatively the effectiveness of the various protection systems. More specifically, the assessment involved a direct comparison of the damage reduction provided by each protection system with respect to the severe degradation experienced by the corresponding non‐protected frame. Structural damage, non‐structural damage and damage to contents were used on purpose and included in a subsequent phase of cost analysis to evaluate the expected gains also in terms of economic benefits and life loss prevention. The results indicate that base isolation, when applicable, provides higher degrees of safety than energy dissipation does; moreover, the use of SMA‐based devices generally brings about better performances, also in consideration of the reduced functional and maintenance requirements. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Analysis and simulation of magma mixing processes in 3D   总被引：2，自引：0，他引：2  

D. Perugini  G. Poli  G. D. Gatta 《Lithos》2002,65(3-4):313-330

Magma mixing structures from the lava flow of Lesbos (Greece) are analyzed in three dimensions using a technique that, starting from the serial sections of rock cubes, allows the reconstruction of the spatial distribution of magmas inside rocks. Two main kinds of coexisting structures are observed: (i) “active regions” (AR) in which magmas mix intimately generating wide contact surfaces and (ii) “coherent regions” (CR) of more mafic magma that have a globular shape and do not show large deformations. The intensity of mingling is quantified by calculating both the interfacial area (IA) between interacting magmas and the fractal dimension of the reconstructed structures. Results show that the fractal dimension is linearly correlated with the logarithm of interfacial area allowing discrimination among different intensities of mingling.

The process of mingling of magmas is simulated using a three-dimensional chaotic dynamical system consisting of stretching and folding processes. The intensity of mingling is measured by calculating the interfacial area between interacting magmas and the fractal dimension, as for natural magma mixing structures. Results suggest that, as in the natural case, the fractal dimension is linearly correlated with the logarithm of the interfacial area allowing to conclude that magma mixing can be regarded as a chaotic process.

Since chemical exchange and physical dispersion of one magma inside another by stretching and folding are closely related, we performed coupled numerical simulations of chaotic advection and chemical diffusion in three dimensions. Our analysis reveals the occurrence in the same system of “active mixing regions” and “coherent regions” analogous to those observed in nature. We will show that the dynamic processes are able to generate magmas with wide spatial heterogeneity related to the occurrence of magmatic enclaves inside host rocks in both plutonic and volcanic environments.  相似文献   

An Early-Cambrian UPb apatite cooling age for the high-temperature regional metamorphism in the Piancó area,Borborema Province (NE Brazil): initial conclusions     

Bruno Dhuime  Delphine Bosch  Olivier Bruguier  Renaud Caby  Carlos Archanjo 《Comptes Rendus Geoscience》2003,335(15):1081-1089

The Borborema Province (BP) of northeastern Brazil is a complex crustal assemblage, which has undergone a polycyclic evolution during the Proterozoic. In the Piancó-Alto Br??gida belt, a metamorphosed leucosome vein inserted in amphibolites has a trace element pattern suggesting a T-MORB protolith. Apatites yield a REE pattern indicating growth in equilibrium with garnet, thus pointing to its metamorphic origin. UPb analyses yield an age of 540±5 Ma interpreted as a cooling age following amphibolite facies regional metamorphism associated with granitic emplacement at ca. 580 Ma. The resulting slow cooling rates (ranging from ca. 2.5 to 5 °C Ma^?1) are consistent with underplating of mafic magmas, or crustal thickening caused by nappe stacking, as possible processes governing the metamorphic evolution of the BP. To cite this article: B. Dhuime et al., C. R. Geoscience 335 (2003).  相似文献   

Structural setting of the Bay of Naples (Italy) seismic reflection data: implications for Campanian volcanism: [Tectonophysics 372 (2003) 193–213]     

Pier Paolo G. Bruno  Antonio Rapolla  Vincenzo Di Fiore 《Tectonophysics》2003,376(3-4)

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Réponse aux commentaires d'Azambre et al. et de Rapaille et al.: [C. R. Geoscience 334 (2002) 197]     

Christian Desreumaux  Bernard Clément  Richard Fabre  Bruno Martins-Campina 《Comptes Rendus Geoscience》2004,336(2):173-174

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