A Bayesian non-parametric method to detect clusters in Planck data     

J. M. Diego  P. Vielva  E. Martínez-González  J. Silk  J. L. Sanz 《Monthly notices of the Royal Astronomical Society》2002,336(4):1351-1363

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Radio emission in active galaxies: the starburst scenario     

Luis Colina  Diego Perez-Olea 《Astrophysics and Space Science》1993,205(1):99-105

The origin of the radio emission in active galaxies ranging from LINERS to ultraluminous IRAS galaxies is considered under the scenario of a violent nuclear or circumnuclear starburst. The radio luminosity is explained as non-thermal radio emission generated in supernova remnants (SNRs). Implications of this scenario in terms of the radio brightness of SNRs, the supernovae rates, and their detectability are discussed.  相似文献   

Las Matras Block, Central Argentina (37°S-67°W): the Southernmost Cuyania Terrane and its Relationship with the Famatinian Orogeny     

Ana María Sato  Hugo Tickyj  Eduardo Jorge Llambías  Miguel Angelo Stipp Basei  Pablo Diego Gonzlez 《Gondwana Research》2004,7(4):1077-1087

The Las Matras Block in Central Argentina constitutes the southernmost part of the Cuyania terrane, which was accreted to the southwestern margin of Gondwana during the Early to Mid Ordovician Famatinian orogeny. The Grenville-aged rocks of the Las Matras Block are represented by the tonalitic to trondhjemitic Las Matras pluton. A new U-Pb conventional zircon age of 1244±42 Ma confirms previous Sm-Nd and Rb-Sr isochron ages of this pluton. Mineral composition data are consistent with the tonalitic-trondhjemitic character of the pluton, and constrain its emplacement level to 1.9 to 2.6 kb. This shallow level of emplacement and the undeformed character of the pluton are distinctive features of this southernmost basement. A regional comparison indicates that the igneous-metamorphic evolution of the Grenville-aged basement rocks of the Cuyania terrane occurred over a period of more than 200 million years, with ages older than 1200 Ma up to those close to 1000 Ma. The shallowest crustal level is found in Las Matras, suggesting a southward shallowing of the exposed level of basement. The deformation and metamorphism associated with the collisional Famatinian orogeny affect both the Cuyania terrane and the adjacent western margin of Gondwana, and the Gondwana margin was also the locus of the related arc magmatism, but the compressive effects of the collision decrease in intensity toward the south. The Famatinian metamorphism and magmatism continue even further south into the Patagonia region, but the southern continuity of the Cuyania terrane into this region remains uncertain.  相似文献   

Secondary gravitational anisotropies in open universes     

Vicent Quilis  & Diego Sáez 《Monthly notices of the Royal Astronomical Society》1998,293(3):306-314

The applicability of the potential approximation in the case of open universes is tested. Great Attractor-like structures are considered in the test. Previous estimates of the cosmic microwave background anisotropies produced by these structures are analysed and interpreted. The anisotropies corresponding to inhomogeneous ellipsoidal models are also computed. It is proved that, whatever the spatial symmetry may be, Great Attractor-like objects with extended cores (radii ∼10 h ⁻¹), located at redshift z =5.9 in an open universe with density parameter Ω₀=0.2, produce secondary gravitational anisotropies of the order of 10⁻⁵ on angular scales of a few degrees. The amplitudes and angular scales of the estimated anisotropy decrease as the Great Attractor size decreases. For comparable normalizations and compensations, the anisotropy produced by spherical realizations is found to be smaller than that of ellipsoidal models. This anisotropy appears to be an integrated effect along the photon geodesics. Its angular scale is much greater than that subtended by the Great Attractor itself. This is easily understood by taking into account the fact that the integrated effect is produced by the variations of the gravitational potential, which seem to be important in large regions subtending angular scales of several degrees. As a result of the large size of these regions, the spatial curvature of the universe becomes important and, consequently, significant errors (∼30 per cent) arise in estimates based on the potential approximation. As is emphasized in this paper, two facts should be taken into account carefully in some numerical estimates of secondary gravitational anisotropies in open universes: (1) the importance of scales much greater than those subtended by the cosmological structures themselves, and (2) the compatibility of the potential approximation with the largest scales.  相似文献   

Do Solar Flares Affect Total Ozone?     

Diego Marin  Jan Laštovička 《Studia Geophysica et Geodaetica》1998,42(4):533-539

An analysis of total ozone from Hradec Králové (50.25°N, 15.21°E) and of radio wave absorption in the lower ionosphere at 1539 kHz (reflection point 50.3°N, 11.8°E) shows that there is no detectable effect of strong solar flares in total ozone, no correlation between total ozone and absorption on a day-to-day time scale, and that strong solar flares do not affect this correlation. Thus the long-term correlation of monthly average values (Alberca et al., 1996) is not reproduced on a day-to-day time scale, and the effects of strong geomagnetic storms in total ozone (Latovika et al., 1992; Mlch and Latovika, 1996) have no counterpart in effects of strong solar flares.  相似文献   

南菲律宾地区类埃达克岩和富铌玄武质熔岩的成因   总被引：7，自引：3，他引：7  

PaternoRCASTILLO 《岩石学报》2002,18(2):143-151

埃达克岩（adakite)最初 是指由消减板片玄武岩物质熔融形成的富硅、富钠、高Sr/Y和La/Yb比值的弧火山熔岩。它通常产在会聚带，这个部位的年轻的、因而仍然是热的大洋板片正在发生俯冲消减。富铌的岛弦玄武央进则是吕等到高碱的镁铁质熔岩，它们相对于正常的岛弦玄武岩含有较多的高场强元素（HFSE）。这些玄武岩通常与埃达克央共生， 这一组合是直被用于论证他们的高HFSE含量是因为他们的地幔源区受到板片来源的熔体的交代。先前的区域研究结果表明，南菲律宾是埃达克岩和富铌岛孤玄武岩的一个典型产地。然而最近的详细研究显示，尽管该地区的一些岛弧火山岩是类埃达克岩的，但是它们很可能是来自地幔楔的母岩浆的分异作用的产物，而这里的地幔楔主要是受沉积来源的成分交代的，此外，菲律宾南部最典型的富铌熔岩中HFSE的富集，也很有可能是起因于似乎是西太平洋边缘特有的富集地幔组分的熔融。这些结果提出了如下问题：南菲律宾是否存在真正的板片来源的熔体？这里的富铌岛弧 熔岩是否起因于地幔楔被这种熔体交代？  相似文献   

Transport of dissolved organic nitrogen in Mississippi River plume and Texas-Louisiana continental shelf near-surface waters     

Diego López-Veneroni  Luis A. Cifuentes 《Estuaries and Coasts》1994,17(4):796-808

Dissolved organic nitrogen (DON) in near-surface (<20 m depth) waters of the Texas-Louisiana continental shelf is the predominant form of total dissolved nitrogen that is advected by the Mississippi-Atchafalaya River plume. Relatively high DON concentrations associated with low-salinity (<33 psu) waters throughout the year can be traced within the plume along the Texas-Louisiana inner shelf. DON concentrations throughout the shelf were significantly higher near the Mississippi-Atchafalaya outflow region relative to downstream inner Gulf shelf locations. Significant intercruise variations were also evident, with the highest concentrations during May 1992 and lower values in October 1992. At a fixed location off the Mississippi River outflow region DON concentration covaried inversely with salinity on time scales of hours to months, confirming that source water is a determining factor for variations of bulk DON concentrations in the region. Similar variations in upper water DON concentrations at different locations and seasons occurred in both plume and nonplume waters, which resembled the seasonal concentration changes of riverine nitrogen, and show that this pool is useful in tracing the influence of riverine-derived nitrogen on the overall nitrogen balance of the NW Gulf of Mexico’s continental shelf. Plume and nonplume DON concentrations deviated from mixing lines between riverine and oceanic endmembers, suggesting that plume waters may be a sink and nonplume waters may be a source of a labile fraction of DON in the region.  相似文献   

Stratigraphy and formation processes of the Upper Pleistocene deposit at Gruta da Oliveira,Almonda karstic system,Torres Novas,Portugal     

Diego E. Angelucci  Joo Zilho 《Geoarchaeology》2009,24(3):277-310

Gruta da Oliveira is a cave located in the Almonda karstic system in central Portugal. Its Upper Pleistocene fill is made up of gravitational sediments with varied biogenic and anthropogenic inputs. The archaeological sequence (35–70 ka) is fairly homogeneous, reflecting a predominantly moist climatic context modulated by millennial‐scale variations. Human occupation was almost continuous throughout. In the richer archaeological layers (8–14), the anthropogenic components are in primary position, and post‐depositional processes are restricted, although penecontemporaneous biological activity—such as hyena scavenging—overprinted the record. In layers 15–19, the excavated area corresponds to the footslope of a talus, where accumulation proceeded mainly through runoff and where the lithics and bones derive from occupations situated ca. 5m outward. The base of the deposit is >2m from the current base of the excavation, suggesting that Oxygen Isotope Stage (OIS)‐4 and OIS‐5 sediments underlay the deposit already exposed. This study confirms the archaeological integrity of the Mousterian assemblages found in the different layers, and, given the dates for layer 8, supports the hypothesis that Neanderthals survived in western Iberia until at least 35,000–38,000 calendar years ago. © 2009 Wiley Periodicals, Inc.  相似文献   

Sedimentary processes and provenance of Quaternary marine formations from the Tangier Peninsula (Northern Rif, Morocco)     

Khadija Aboumaria  Mohamed Najib Zaghloul  Maria Battaglia  Francesco Loiacono  Diego Puglisi  M&#x;hamed Aberkan 《Journal of African Earth Sciences》2009,55(1-2):10

This work deals with new lithostratigraphic, sedimentological, petrographic and geochemical data collected from coastal Quaternary formations of the Tangier Peninsula along the Northern Atlantic and Mediterranean coasts in the southern side of the Gibraltar Strait (Morocco).The sedimentological features of the analyzed sections reflect a palaeoenvironment evolution from a submerged beach-type to a high energy littoral depositional system, namely lower shoreface to beachface environment with a regressive trend to thickening- and coarsening-upward sequences. Other successions, located nearby Larache city and in the Sidi Kankouch area, are also characterized by a positive trend to fining- and thinning-upward sequences, reflecting an evolution from lower beachface or upper shoreface to lower shoreface. It is possible that the transgressive to regressive trend inversion could be related to fluctuations of sediment input rate versus accommodation space during the progradation of a coastal palaeoenvironment.The lateral and vertical evolution of the studied marine formations is related to late Quaternary neotectonics, mainly to the last repercussions of isostatic rebound of the External and Flysch Basin Domains, during a period of relatively uniform sea level between 280,000 and 125,000 years B.P.The provenance of arenites of these Quaternary marine formations, studied by means of modal counting and geochemical analysis, seems to be linked mainly to Middle-Upper Miocene and Pliocene terrigenous successions, unconformably resting on various formations of the Neogene accretionary prism. The latter has been built by the stacking of Flysch Nappes and External Units of the Northern Rif Chain.  相似文献   

A Ta,Ti–rich oxide mineral assemblage from the Nancy beryl–columbite–phosphate granitic pegmatite,San Luis,Argentina     

Galliski  Miguel Ángel  Márquez-Zavalía  María Florencia  Škoda  Radek  Novák  Milan  Čopjaková  Renata  Pagano  Diego Sebastián 《Mineralogy and Petrology》2019,113(5):687-701

Mineralogy and Petrology - An assemblage of tantalite-(Mn), tantalian rutile, tapiolite-(Fe), titanowodginite, ferrotitanowodginite, and hydroxycalciomicrolite occurs in the Nancy granitic...  相似文献