697 research outputs found
Outflows from active galactic nuclei: The BLR-NLR metallicity correlation
The metallicity of active galactic nuclei (AGNs), which can be measured by
emission line ratios in their broad and narrow line regions (BLRs and NLRs),
provides invaluable information about the physical connection between the
different components of AGNs. From the archival databases of the International
Ultraviolet Explorer, the Hubble Space Telescope and the Sloan Digital Sky
Survey, we have assembled the largest sample available of AGNs which have
adequate spectra in both the optical and ultraviolet bands to measure the
narrow line ratio [N II]/H{\alpha} and also, in the same objects, the
broad-line N V/C IV ratio. These permit the measurement of the metallicities in
the NLRs and BLRs in the same objects. We find that neither the BLR nor the NLR
metallicity correlate with black hole masses or Eddington ratios, but there is
a strong correlation between NLR and BLR metallicities. This metallicity
correlation implies that outflows from BLRs carry metal-rich gas to NLRs at
characteristic radial distances of ~ 1.0 kiloparsec. This chemical connection
provides evidence for a kinetic feedback of the outflows to their hosts. Metals
transported into the NLR enhance the cooling of the ISM in this region, leading
to local star formation after the AGNs turn to narrow line LINERs. This
post-AGN star formation is predicted to be observable as an excess continuum
emission from the host galaxies in the near infrared and ultraviolet, which
needs to be further explored.Comment: 19 pages, 13 figures, 3 tables. Accepted for publication at MNRA
Fully integrated InGaAs/InP single-photon detector module with gigahertz sine wave gating
InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of
GHz clock rates are crucial components for the high-speed quantum key
distribution (QKD). We have developed for the first time a compact, stable and
user-friendly tabletop InGaAs/InP single-photon detector system operating at a
1.25 GHz gate rate that fully integrates functions for controlling and
optimizing SPAD performance. We characterize the key parameters of the detector
system and test the long-term stability of the system for continuous operation
of 75 hours. The detector system can substantially enhance QKD performance and
our present work paves the way for practical high-speed QKD applications.Comment: 11 pages, 6 figures. Accepted for publication in Review of Scientific
Instrument
1,3-Di-4-pyridylpropane–2-hydroxybenzene-1,4-dicarboxylic acid (1/2)
In the title compound, C13H14N2·2C8H6O5, which crystallized in the monoclinic C2/c space group, the 1,3-bis(4-pyridyl)propane molecules and 2-hydroxy-1,4-benzenedicarboxylic acid molecules are alternately linked by O—H⋯N and O—H⋯O hydrogen bonds into herringbone/zigzag chains
Autoimmune Response Confers Decreased Cardiac Function in Patients with Rheumatic Mitral Lesion following Valve Replacement
Purpose: To explore the effect of autoimmune response on the decreased cardiac function in patients with rheumatic mitral lesion following valve replacement.Methods: In this case-controlled study, 29 patients who had undergone valve replacement as a result of mitral lesion were enrolled (mean age = 48.7 years). Twenty healthy volunteers were selected as control (mean age = 47.5 years). Plasma levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), high –sensitivity C-reactive protein (hs-CRP) and echocardiographic indices of heart function in the two groups were investigated, respectively. Body mass index (BMI) was also calculated.Results: TNF-α, IL-6 and hs-CRP levels in plasma were significantly higher than those in controls (p < 0.05; 22.23 pg/mL vs. 13.24 pg/mL, 53.42 pg/mL vs. 9.57 pg/mL, and 2.12 μg/mL vs. 0.97 μg/mL, respectively). The indices of left atrial diameter (LAD), left ventricular end-diastolic diameter (LDD) and isovolumetric contraction time (ICT) were significantly higher (p < 0.05; 4.72 cm vs. 3.78 cm, 4.85 cm vs. 4.37 cm, and 76.38 ms vs. 66.24 ms, respectively), but those of early diastolic velocity (Ea), late diastolic velocities (Aa) and ejection time (ET) were significantly lower (p < 0.05; 7.65 cm/s vs. 16.8 cm/s, 5.56 cm/s vs. 12.9 cm/s, and 261.54 ms vs. 276.14 ms, respectively). Two-dimensional echocardiography obtained the same results.Conclusion: Valve replacement in patients with rheumatic heart disease (RHD) does not attenuate inflammatory response; rather, autoimmune response would keep affecting decreased heart function in RHD patients who have received mitral valve replacement.Keywords: Tumor necrosis factor-α, Interleukin-6, High sensitivity C reactive protein, Mitral lesion, Mitral valve replacemen
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