排序方式： 共有32条查询结果，搜索用时 31 毫秒
11.
12.
G. B. Taylor N. E. Gugliucci A. C. Fabian J. S. Sanders G. Gentile S. W. Allen 《Monthly notices of the Royal Astronomical Society》2006,368(4):1500-1506
We present Very Long Baseline Array (VLBA) observations of the nucleus of NGC 1275, the central, dominant galaxy in the Perseus cluster of galaxies. These are the first observations to resolve the linearly polarized emission from 3C 84, and from them we determine a Faraday rotation measure (RM) ranging from 6500 to 7500 rad m−2 across the tip of the bright southern jet component. At 22 GHz some polarization is also detected from the central pc of 3C 84, indicating the presence of even more extreme RMs that depolarize the core at lower frequencies. The nature of the Faraday screen is most consistent with being produced by magnetic fields associated with the optical filaments of ionized gas in the Perseus cluster. 相似文献
13.
14.
Michael Gentile 《Urban geography》2013,34(10):1455-1464
ABSTRACTDespite the recent planetary turn that has swept through gentrification research, the theoretical barycentre remains pegged to a few strongholds located in the global north-west. Against this background, this essay offers a provincialized account of three gentrification-like trends – tele-urbanization, Schengtrification and colour-splashing – which are currently taking place in Tbilisi, Riga and Kiev. It is proposed that these processes are supported by an underlying logic that is not pinned to these cities’ specific (“post-communist”) contexts, raising questions about the avowedly universal validity of theories of gentrification stemming from the global northwest, and particularly those developed within the more critical scholarly tradition. 相似文献
15.
P. Salucci A. Lapi C. Tonini G. Gentile I. Yegorova U. Klein 《Monthly notices of the Royal Astronomical Society》2007,378(1):41-47
In the current ΛCDM cosmological scenario, N -body simulations provide us with a universal mass profile, and consequently a universal equilibrium circular velocity of the virialized objects, as galaxies. In this paper we obtain, by combining kinematical data of their inner regions with global observational properties, the universal rotation curve of disc galaxies and the corresponding mass distribution out to their virial radius. This curve extends the results of Paper I, concerning the inner luminous regions of Sb–Im spirals, out to the edge of the galaxy haloes. 相似文献
16.
17.
18.
19.
The work deals with the identification of modal parameters of a structure from earthquake records when the input ground motion is unknown. This may occur, for example, owing to instrumental malfunctions. The procedure is based on the assumption that at least two responses are available and consists of two main steps. In the first one, modal frequencies are estimated by searching relative minima of a function that involves the ratio of the Fourier amplitudes of the two records, while the second phase is devoted to the identification of other modal quantities (i.e. effective participation factors and modal dampings). Once the identification process has been completed, an estimate of the unknown base input may be performed by means of the IFFT algorithm. The proposed approach has been checked against both finite element simulations of simple structures and field measurements on real buildings. 相似文献
20.
F. Donato G. Gentile P. Salucci C. Frigerio Martins M. I. Wilkinson G. Gilmore E. K. Grebel A. Koch R. Wyse 《Monthly notices of the Royal Astronomical Society》2009,397(3):1169-1176
We confirm and extend the recent finding that the central surface density μ0D ≡ r 0 ρ0 of galaxy dark matter haloes, where r 0 and ρ0 are the halo core radius and central density, is nearly constant and independent of galaxy luminosity. Based on the co-added rotation curves (RCs) of ∼1000 spiral galaxies, the mass models of individual dwarf irregular and spiral galaxies of late and early types with high-quality RCs, and the galaxy–galaxy weak-lensing signals from a sample of spiral and elliptical galaxies, we find that log μ0D = 2.15 ± 0.2 in units of log(M⊙ pc−2 ) . We also show that the observed kinematics of Local Group dwarf spheroidal galaxies are consistent with this value. Our results are obtained for galactic systems spanning over 14 mag, belonging to different Hubble types and whose mass profiles have been determined by several independent methods. In the same objects, the approximate constancy of μ0D is in sharp contrast to the systematical variations, by several orders of magnitude, of galaxy properties, including ρ0 and central stellar surface density. 相似文献