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91.
K. Bensch A. del Olmo J. Sulentic J. Perea P. Marziani 《Journal of Astrophysics and Astronomy》2015,36(4)
We present a preliminary analysis of X-ray data of quasars in the context of the 4D eigenvector 1 parameter space (Sulentic et al. 2000a, b). 4DE1 serves as a surrogate H-R diagram for representing empirical diversity among quasars and identifying the physical drivers of the diversity. The soft X-ray spectral index (Γsoft) was adopted as one of the key 4DE1 that correlates contrasting extremes in Type 1 properties. 4DE1 motivated the hypothesis of two quasar populations (A and B) divided by L/L EDD≈0.2. Pop. A is a largely radio-quiet population with FWHM H β<4000 km/s and often showing a soft X-ray excess. Pop. B is a mix of radio-quiet and a majority of RL quasars shows only a hard X-ray power-law SED. The X-ray separation was based upon earlier ROSAT and ASCA data but we now confirm this dichotomy with large samples of X-ray spectra obtained with XMM-Newton and SWIFT. One popular idea connects the soft excess in Pop. A quasars as a signature of thermal emission from a hot accretion disk in sources radiating close to the Eddington limit. 相似文献
92.
Jos Luis Orgeira Mariela del Carmen Alderete Yohana Gisell Jimnez Juan Cruz Gonzlez 《极地研究(英文版)》2015,(2)
The Scotia Sea is one of the most biologically rich regions of Antarctica, and it hosts a large community of upper trophic-level predators. Long-term at-sea monitoring provides valuable information on ... 相似文献
93.
A. A. Hakobyan A. R. Petrosian G. A. Mamon B. McLean D. Kunth M. Turatto E. Cappelaro F. Mannucci R. J. Allen N. Panagia M. Della Valle 《Astrophysics》2009,52(1):40-53
The determination of the supernova (SN) rate is based not only on the number of detected events, but also on the properties
of the parent galaxy population. This is the first paper of a series aimed at obtaining new, refined, SN rates from a set
of five SN surveys, by making use of a joint analysis of near-infrared (NIR) data. We describe the properties of the 3838
galaxies that were monitored for SNe events, including newly determined morphologies and their DENIS, and POSS-II/UKST I,
2MASS and DENIS J and Ks and 2MASS H magnitudes. We have compared 2MASS, DENIS and POSS-II/UKST IJK magnitudes in order to find possible systematic
photometric shifts in the measurements. The DENIS and POSS-II/UKST I band magnitudes show large discrepancies (mean absolute
difference of 0.4 mag.), mostly due to different spectral responses of the two instruments, with an important contribution
(0.33 mag rms) from the large uncertainties in the photometric calibration of the POSS-II and UKST photographic plates. In
the other wavebands, the limiting near infrared magnitude, morphology, and inclination of the galaxies are the most influential
factors which affect the determination of photometry of the galaxies. Nevertheless, no significant systematic differences
have been found between any pair of NIR magnitude measurements, except for a few percent of galaxies showing large discrepancies.
This allows us to combine DENIS and 2MASS data for the J and Ks filters.
Published in Astrofizika, Vol. 52, No. 1, pp. 47–62 (Februay 2009). 相似文献
94.
95.
An expansive clayey rock belonging to the Asturias Carboniferous of NW Spain has been petrophysically characterized before, during and after swelling tests. The evolution of the microfissuring and the induced deterioration have been studied by acoustic emission during tests and by ultrasonic techniques before and after swelling/contraction cycles. A good correlation has been found between the AE curves and swelling strain. Damage due to the generation and growth of microfissures is most important during the first moments of each swelling/contraction cycle. Microfissures mainly develop in the direction of the foliation planes, as can be shown by linear crack density and measurements of the propagation velocity of longitudinal waves. 相似文献
96.
97.
Prof. Dr. J. Büdel 《International Journal of Earth Sciences》1960,50(1):290-291
Ohne ZusammenfassungKurzreferat. Eine ausführlichere Darstellung folgt in einem der nächsten Bände dieser Zeitschrift. 相似文献
98.
Time series of velocity profiles at two Chesapeake Bay entrance sites were used to characterize the subtidal variability of transverse flows off a cape. A shallow sampling site was located near Cape Henry over 6 m of water and separated from a deep site, 20 m deep, by a distance of 4 km. The velocity profiles showed that wind-induced subtidal variations in general masked curvature effects (centrifugal accelerations) that may produce secondary circulation associated with tidal flow around a cape. Such secondary circulation, consisting of flow away from the cape at surface and toward the cape at depth, was observed only during periods of weak winds. Most of the time, transverse flows were unidirectional throughout the water column and moved in opposite directions at the two sites examined. This caused convergence of transverse flow between the two sites under the influence of northerly winds and divergence of transverse flow with southwesterly winds. In addition to unidirectional and curvature-induced secondary flows, other modes of subtidal variability consisted of (1) two-layered responses with surface flow toward the cape, and (2) three-layered responses. These two- and three-layered structures were observed more frequently at the deep site, where greater stratification is expected, than at the shallow site.Responsible Editor: Iris Grabemann 相似文献
99.
Julien Vaudan Aurèle Parriaux Laurent Tacher Gianni della Valle 《Eclogae Geologicae Helvetiae》2005,98(3):371-383
The alpine valley of the Haute-Sarine is on several accounts representative of the alluvial aquifers of mountain by its very
environment and its hydrogeologic characteristics. The investigations and the analysis carried out within the framework of
this study enabled us to improve knowledge on the Quaternary filling of the valley and to highlight the preferential supplies
of the aquifer by infiltration of the river and precipitations and also by the underground contributions of evaporitic karsts.
We also could note the opulence of groundwater resources of the Haute-Sarine both from the qualitative and the quantitative
points of view. The knowledge of these typical characteristics of alluvial aquifers of high altitude allowed finally the development
of a concept of management and protection of groundwater resources that falls under a sustainable development policy of the
groundwater storage in the alpine areas.
Manuscrit re?u le 4 février 2003 Révision acceptée le 30 mars 2005 相似文献
100.
Visualization of Volcanic Rock Geochemical Data and Classification with Artificial Neural Networks 总被引:1,自引:0,他引:1
Juan Pablo Lacassie Javier Ruiz del Solar Barry Roser Francisco Hervé 《Mathematical Geology》2006,38(6):697-710
An unsupervised neural network technique, Growing Cell Structures (GCS) was used to visualize geochemical differences between
four different island arc volcanic rock types: basalts, andesites, dacites and rhyolites. The output of the method shows the
cluster structure of the dataset clearly, and the relevant geochemical patterns and relationships between its variables. The
data can be separated into four clusters, each associated with a specific volcanic rock type (basalt, andesite, dacite and
rhyolite), according to a unique combination of major element concentrations. Following clustering, performance of the trained
GCS network as a classifier of volcanic rock type was tested using two test datasets with major element concentration data
for 312 and 496 island arc volcanic rock samples of known volcanic type. Preliminary classification results are promising.
In the first test dataset 94% of basalts, 76% of andesites, 83% of dacites and 100% of the rhyolites were classified correctly.
Successful classification rates in the second dataset were 100%, 80%, 77%, and 98% respectively. The success of the analysis
suggests that neural networks analysis constitutes a useful analytical tool for identification of natural clusters and examination
of the relationships between numeric variables in large datasets, and that can be used for automatic classification of new
data. 相似文献