114 research outputs found

    J1145-0033 - the most distant giant radio source?

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    We present J1145-0033, a candidate for the most distant (z=2.055) lobe-dominated giant radio quasar, with a projected linear size of 1.34 Mpc. This quasar has both FR II -- type radio morphology and broad absorption lines in its optical spectrum. Some physical characteristics (e.g. black hole mass, accretion rate, equipartition magnetic field, energy density and particle density of ambient medium) based on the optical and radio data are provided. We have also found that the quasar has a relatively large central black hole mass and a very small accretion rate in comparison with similar objects.Comment: 12 pages, 4 Postscript figure

    Pulsational Mapping of Calcium Across the Surface of a White Dwarf

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    We constrain the distribution of calcium across the surface of the white dwarf star G29-38 by combining time series spectroscopy from Gemini-North with global time series photometry from the Whole Earth Telescope. G29-38 is actively accreting metals from a known debris disk. Since the metals sink significantly faster than they mix across the surface, any inhomogeneity in the accretion process will appear as an inhomogeneity of the metals on the surface of the star. We measure the flux amplitudes and the calcium equivalent width amplitudes for two large pulsations excited on G29-38 in 2008. The ratio of these amplitudes best fits a model for polar accretion of calcium and rules out equatorial accretion.Comment: Accepted to the Astrophysical Journal. 16 pages, 10 figures

    Detection of a tertiary brown dwarf companion in the sdB-type eclipsing binary HS 0705+6700

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    HS 0705+6700 is a short-period (P=2.3 hours), close binary containing a hot sdB-type primary and a fully convective secondary. We have monitored this eclipsing binary for more than 2 years and as a result, 32 times of light minimum were obtained. Based on our new eclipse times together with these compiled from the literature, it is discovered that the O-C curve of HS 0705+6700 shows a cyclic variation with a period of 7.15 years and a semiamplitude of 92.4 s. The periodic change was analyzed for the light-travel time effect that may be due to the presence of a tertiary companion. The mass of the third body is determined to be M3 sin i = 0.0377 (+/-0.0043) Msun when a total mass of 0.617 Msun for HS 0705+6700 is adopted. For orbital inclinations i >= 32.8, the mass of the tertiary component would be below the stable hydrogen-burning limit of M3~0.072 Msun, and thus it would be a brown dwarf. The third body is orbiting the sdB-type binary at a distance shorter than 3.6 astronomical units (AU). HS 0705+6700 was formed through the evolution of a common envelope after the primary becomes a red giant. The detection of a sub-stellar companion in HS 0705+6700 system at this distance from the binary could give some constraints on stellar evolution in such systems and the interactions between red giants and their companions.Comment: 10 pages, 3 figures To be published in Astrophysical Journa

    Identification of human CD4+ T cell populations with distinct antitumor activity

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    How naturally arising human CD4+ T helper subsets affect cancer immunotherapy is unclear. We reported that human CD4+CD26high T cells elicit potent immunity against solid tumors. As CD26high T cells are often categorized as TH17 cells for their IL-17 production and high CD26 expression, we posited these populations would have similar molecular properties. Here, we reveal that CD26high T cells are epigenetically and transcriptionally distinct from TH17 cells. Of clinical importance, CD26high and TH17 cells engineered with a chimeric antigen receptor (CAR) regressed large human tumors to a greater extent than enriched TH1 or TH2 cells. Only human CD26high T cells mediated curative responses, even when redirected with a suboptimal CAR and without aid by CD8+ CAR T cells. CD26high T cells cosecreted effector cytokines, produced cytotoxic molecules, and persisted long term. Collectively, our work underscores the promise of CD4+ T cell populations to improve durability of solid tumor therapies

    Is adenomyosis the neglected phenotype of an endomyometrial dysfunction syndrome?

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    Since the dissociation between adenomyoma and endometriosis in the 1920s and the laparoscopic progress in the diagnosis and surgery of endometriosis, the literature has been greatly focused on the disease endometriosis. The study of adenomyosis, on the other hand, has been neglected as the diagnosis remained based on hysterectomy specimens. However, since the introduction of magnetic resonance and sonographic imaging techniques in the 1980s, the myometrial junctional zone has been identified as a third uterine zone and interest in adenomyosis was renewed. This has also been the start for the interest in the role of the myometrial junctional zone dysfunction and adenomyosis in reproductive and obstetrical disorders

    Stochastic Modeling of Multiwavelength Variability of the Classical BL Lac Object OJ287 on Timescales Ranging from Decades to Hours

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    We present the results of our power spectral density analysis for the BL Lac object OJ 287, utilizing the Fermi-LAT survey at high-energy.-rays, Swift-XRT in X-rays, several ground-based telescopes and the Kepler satellite in the optical, and radio telescopes at GHz frequencies. The light curves are modeled in terms of continuous-time autoregressive moving average (CARMA) processes. Owing to the inclusion of the Kepler data, we were able to construct for the first time the optical variability power spectrum of a blazar without any gaps across similar to 6 dex in temporal frequencies. Our analysis reveals that the radio power spectra are of a colored-noise type on timescales ranging from tens of years down to months, with no evidence for breaks or other spectral features. The overall optical power spectrum is also consistent with a colored noise on the variability timescales ranging from 117 years down to hours, with no hints of any quasi-periodic oscillations. The X-ray power spectrum resembles the radio and optical power spectra on the analogous timescales ranging from tens of years down to months. Finally, the.-ray power spectrum is noticeably different from the radio, optical, and X-ray power spectra of the source: we have detected a characteristic relaxation timescale in the Fermi-LAT data, corresponding to similar to 150 days, such that on timescales longer than this, the power spectrum is consistent with uncorrelated (white) noise, while on shorter variability timescales there is correlated (colored) noise

    Preliminary Monte Carlo approach to complex technical system reliability analysis

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    The paper explores the mathematical and computer modeling of complex technical systems related to their operation processes. The complex technical system with the reliability structure and components’ reliability parameters changing at the various operation states is defined. The selected system operation process parameters and the hypothetical distribution functions of the conditional sojourn times at the operation states are defined and identified. The reliability functions of the multistate system and components are introduced and their parameters are identified. The Monte Carlo simulation method is proposed to the complex system reliability evaluation. Moreover, the proposed theoretical and simulation tools are supported with the practical application to the multi-state port oil piping transportation system reliability analysis

    Monte Carlo simulation for reliability assessment and optimization of an object subjected to varying operation conditions

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    This paper presents the computer simulation technique related to the reliability of an object under variable operation conditions. The considered object operation process is modelled using semi-Markov processes and its reliability is analysed by application of the conditional reliability functions in its different operation states. The backgrounds and procedures of the Monte Carlo simulation method application to an object at variable condition reliability analysis are proposed and applied to reliability evaluation of an exemplary object. Consequently, under arbitrarily assumed the parameters of this exemplary object operation process and its conditional reliability functions, using the proposed Monte Carlo simulation procedures, the transient probabilities of the exemplary object operation process at the particular operation states and its unconditional reliability function are determined. Further, the linear programming is introduced and proposed to reliability optimization of an object at variable operation conditions and the optimal transient probabilities of the exemplary object operation process at the particular operation states and its optimal unconditional reliability function are determined. Finally, some practical suggestions on the modification of the exemplary object operation process improving its reliability are proposed
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