8 research outputs found
Clustering, Angular Size and Dark Energy
The influence of dark matter inhomogeneities on the angular size-redshift
test is investigated for a large class of flat cosmological models driven by
dark energy plus a cold dark matter component (XCDM model). The results are
presented in two steps. First, the mass inhomogeneities are modeled by a
generalized Zeldovich-Kantowski-Dyer-Roeder (ZKDR) distance which is
characterized by a smoothness parameter and a power index ,
and, second, we provide a statistical analysis to angular size data for a large
sample of milliarcsecond compact radio sources. As a general result, we have
found that the parameter is totally unconstrained by this sample of
angular diameter data.Comment: 9 pages, 7 figures, accepted in Physical Review
Physical parameters of the binary star CM draconis components
Spectra of the eclipsing binary star CM Dra consisting of two M dwarfs are discussed in detail. High-resolution echelle spectra (R = 47000) obtained using the 4.2 m William Hershel telescope are used. The temperatures and metallicities of both components in the binary system are determined using the stellar spectra simulation: T = 3100 +/- 100 K, logg = 5.0 +/- 0.2, [M/H] = -0.5 +/- 0.2 dex. The estimated values are in good agreement with the results obtained by other researchers.Peer reviewe
Chaperone-like activity of immunophilin FKBP12 from bovine brain, a cytoplasmic receptor of immunosuppressor FK506
The carbon abundance and 12C/13C isotopic ratio in the atmosphere of Arcturus from 2.3 µm CO bands
The VSOP 5 GHz AGN survey I. Compilation and observations
The VSOP mission is a Japanese-led project to image radio sources with sub-milliarcsec resolution by correlating the signal from the orbiting 8-m telescope, HALCA, with a global array of telescopes. Twenty-five percent of the scientific time of this mission is devoted to a survey of 402 bright, small-diameter extra-galactic radio sources at 5 GHz. The major goals of the VSOP Survey are statistical in nature: to determine the brightness temperature and approximate structure; to provide a source list for use with future space VLBI missions; and to compare radio properties with other data throughout the EM spectrum. This paper describes: the compilation of a complete list of radio sources associated with active galactic nuclei (AGN); the selection of the subsample of sources to be observed with VSOP; the extensive ground resources used for the Survey; the status of the observations as of 2000 July; the data-analysis methods; and several examples of results from the VSOP Survey. More detailed results from the full sample will be given in future papers
'RadioAstron'-A telescope with a size of 300 000 km: Main parameters and first observational results
The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna ground-space radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of formation of stars and planetary systems in our and other galaxies, interplanetary and interstellar plasma, and the gravitational field of the Earth. The results of ground-based and inflight tests of the space radio telescope carried out in both autonomous and ground-space interferometric regimes are reported. The derived characteristics are in agreement with the main requirements of the project. The astrophysical science program has begun. © 2013 Pleiades Publishing, Ltd
The Neurocircuitry of Fear, Stress, and Anxiety Disorders
Anxiety disorders are a significant problem in the community, and recent neuroimaging research has focused on determining the brain circuits that underlie them. Research on the neurocircuitry of anxiety disorders has its roots in the study of fear circuits in animal models and the study of brain responses to emotional stimuli in healthy humans. We review this research, as well as neuroimaging studies of anxiety disorders. In general, these studies have reported relatively heightened amygdala activation in response to disorder-relevant stimuli in post-traumatic stress disorder, social phobia, and specific phobia. Activation in the insular cortex appears to be heightened in many of the anxiety disorders. Unlike other anxiety disorders, post-traumatic stress disorder is associated with diminished responsivity in the rostral anterior cingulate cortex and adjacent ventral medial prefrontal cortex. Additional research will be needed to (1) clarify the exact role of each component of the fear circuitry in the anxiety disorders, (2) determine whether functional abnormalities identified in the anxiety disorders represent acquired signs of the disorders or vulnerability factors that increase the risk of developing them, (3) link the findings of functional neuroimaging studies with those of neurochemistry studies, and (4) use functional neuroimaging to predict treatment response and assess treatment-related changes in brain function