2,307 research outputs found
Estimate black hole masses of AGNs using ultraviolet emission line properties
Based on the measured sizes of broad line region of the reverberation-mapping
AGN sample, two new empirical relations are introduced to estimate the central
black hole masses of radio-loud high-redshift () AGNs. First, using
the archival spectroscopy data at UV band for the
reverberation-mapping objects, we obtained two new empirical relations between
the BLR size and \Mg/\C emission line luminosity. Secondly, using the newly
determined black hole masses of the reverberation-mapping sample for
calibration, two new relationships for determination of black hole mass with
the full width of half maximum and the luminosity of \Mg/\C line are also
found. We then apply the relations to estimate the black hole masses of AGNs in
Large Bright Quasar Surveyq and a sample of radio-loud quasars. For the objects
with small radio-loudness, the black hole mass estimated using the R_{\rm BLR}
- L_{\eMg/\eC} relation is consistent with that from the relation. But for radio-loud AGNs, the mass estimated
from the R_{BLR} - L_{\eMg/\eC} relation is systematically lower than that
from the continuum luminosity . Because jets could have
significant contributions to the UV/optical continuum luminosity of radio-loud
AGNs, we emphasized again that for radio-loud AGNs, the emission line
luminosity may be a better tracer of the ionizing luminosity than the continuum
luminosity, so that the relations between the BLR size and UV emission line
luminosity should be used to estimate the black hole masses of high redshift
radio-loud AGNs.Comment: 19 pages, 10 figure
Clinical analysis of acute anterior uveitis in 215 cases
AIM: To analyze the etiology, therapeutic effects,risk of relapse and prognosis of acute anterior uveitis.<p>MEHTODS: Medical history of 215 patients with acute anterior uveitis who underwent treatment in Department of Ophthalmology, People's Hospital of Fenghua was collected, together with results of clinical examinations and auxiliary examinations. The data were studied in terms of therapeutic effects, etiological factors, prognosis and relapse rate. <p>RESULTS: In 85 cases(39.5%), the cause was identified, and among the among the most frequent causes were traumatic or surgical injury, viral infection and glaucomatocyclitic crisis. After treatment, the best corrected visual acuity was no less than 1.0 in 153 cases(71.2%), between 0.5 and 1.0 in 55 cases(25.6%), between 0.3 and 0.5 in 4 cases(1.9%), between 0.05 and 0.3 in 2 cases(0.9%), and less than 0.05 in 1 case(0.5%). During the follow-up of more than 6 months, relapse occurred in 4 cases(1.9%)during 4-6 months, in 7 cases(3.2%)during 7-12 months, in 10 cases(4.7%)during 13-24 months, and in 3 cases(1.4%)during 25-60 months. <p>CONCLUSION: The etiology of acute anterior uveitis is complicated and mostly idiopathic. Vision prognosis is good after treatment, but therelapse rate is high and can cause visual impairment, so better understanding should be gained of its relapse and its prevention and early treatment should be emphasized
Study on analysis method for deepwater TTR coupled vibration of parameter vibration and vortex-induced vibration
Considering the vertical vibration, caused by floating platform, of top tensioned riser (TTR), an analysis method for the coupled vibration of parameter excited vibration and vortex-induced vibration is presented in this paper. With the section rotation and shear deformation due to the bending large displacement of TTR, a coupled vibration model of parameter excited vibration and vortex-induced vibration is put forward. And the vortex-induced vibration (VIV) of a TTR for 1500 m water depth is analyzed based on the model. The results show that the vertical vibration caused by floating platform increases transverse vibration displacement of TTR
Fuzzy automata system with application to target recognition based on image processing
AbstractIn order to get better image processing and target recognition, this paper presents a fuzzy automata system to target recognition. The system first performs image processing, and then accomplishes the target recognition. The system consists of four parts: image preprocessing, feature extraction, target matching and experiment. Compared with existing approaches, this paper uses both global features and local features of the target image, and carries out target recognition by using a fuzzy automata system. Simulation results show that the correct recognition rate based on the fuzzy automata system for target recognition is higher at 94.59%, an improvement on an average of 29.24%, compared to other existing approaches. Finally, some directions for future research are described
A resonant feature near the Perseus arm revealed by red clump stars
We investigate the extinction together with the radial velocity dispersion
and distribution of red clump stars in the anti-center direction using spectra
obtained with Hectospec on the MMT. We find that extinction peaks at
Galactocentric radii of about 9.5 and 12.5 kpc, right in front of the locations
of the Perseus and Outer arms and in line with the relative position of dust
and stars in external spiral galaxies. The radial velocity dispersion peaks
around 10kpc, which coincides with the location of the Perseus arm, yields an
estimated arm-interarm density contrast of 1.3-1.5 and is in agreement with
previous studies. Finally, we discover that the radial velocity distribution
bifurcates around 10-11 kpc into two peaks at +27 km/s and -4 km/s. This seems
to be naturally explained by the presence of the outer Lindblad resonance of
the Galactic bar, but further observations will be needed to understand if the
corotation resonance of the spirals arms also plays a role.Comment: 8 pages, 2 figures, accepted for publication in ApJ
The black hole fundamental plane from a uniform sample of radio and X-ray emitting broad line AGNs
We derived the black hole fundamental plane relationship among the 1.4GHz
radio luminosity (L_r), 0.1-2.4keV X-ray luminosity (L_X), and black hole mass
(M) from a uniform broad line SDSS AGN sample including both radio loud and
radio quiet X-ray emitting sources. We found in our sample that the fundamental
plane relation has a very weak dependence on the black hole mass, and a tight
correlation also exists between the Eddington luminosity scaled X-ray and radio
luminosities for the radio quiet subsample. Additionally, we noticed that the
radio quiet and radio loud AGNs have different power-law slopes in the
radio--X-ray non-linear relationship. The radio loud sample displays a slope of
1.39, which seems consistent with the jet dominated X-ray model. However, it
may also be partly due to the relativistic beaming effect. For radio quiet
sample the slope of the radio--X-ray relationship is about 0.85, which is
possibly consistent with the theoretical prediction from the accretion flow
dominated X-ray model. We briefly discuss the reason why our derived
relationship is different from some previous works and expect the future
spectral studies in radio and X-ray bands on individual sources in our sample
to confirm our result.Comment: 23 pages, 7 figures, ApJ accepte
DualApp: Tight Over-Approximation for Neural Network Robustness Verification via Under-Approximation
The robustness of neural networks is fundamental to the hosting system's
reliability and security. Formal verification has been proven to be effective
in providing provable robustness guarantees. To improve the verification
scalability, over-approximating the non-linear activation functions in neural
networks by linear constraints is widely adopted, which transforms the
verification problem into an efficiently solvable linear programming problem.
As over-approximations inevitably introduce overestimation, many efforts have
been dedicated to defining the tightest possible approximations. Recent studies
have however showed that the existing so-called tightest approximations are
superior to each other. In this paper we identify and report an crucial factor
in defining tight approximations, namely the approximation domains of
activation functions. We observe that existing approaches only rely on
overestimated domains, while the corresponding tight approximation may not
necessarily be tight on its actual domain. We propose a novel
under-approximation-guided approach, called dual-approximation, to define tight
over-approximations and two complementary under-approximation algorithms based
on sampling and gradient descent. The overestimated domain guarantees the
soundness while the underestimated one guides the tightness. We implement our
approach into a tool called DualApp and extensively evaluate it on a
comprehensive benchmark of 84 collected and trained neural networks with
different architectures. The experimental results show that DualApp outperforms
the state-of-the-art approximation-based approaches, with up to 71.22%
improvement to the verification result.Comment: 13 pages, 9 fugures, 3 table
X-Ray Repair Cross Complementing 4 (XRCC4) Genetic Single Nucleotide Polymorphisms and the Liver Toxicity of AFB1 in Hepatocellular Carcinoma
Our previous reports have shown that the genetic single-nucleotide polymorphisms (GSNPs) in the DNA repair gene X-ray repair cross complementing 4 (XRCC4) are involved in the carcinogenesis of hepatocellular carcinoma (HCC) induced by aflatoxin B1 (AFB1). However, the effects of GSNPs in the coding regions of XRCC4 on hepatic toxicity of AFB1 have been less investigated. We conducted a hospital-based clinic tissue samples with pathologically diagnosed HCC (n = 380) in a high AFB1 exposure area to explore the possible roles of GSNPs in the coding regions of XRCC4 in AFB1-induced HCC using liver toxicity assays. A total of 143 GSNPs were included in the present study and genotyped using the SNaPshot method, whereas the liver toxicity of AFB1 was evaluated using AFB1-DNA adducts in the tissues with HCC. In the clinicopathological samples with HCC, the average adduct amount is 2.27 ± 1.09 Όmol/mol DNA. Among 143 GSNPs of XRCC4, only rs1237462915, rs28383151, rs762419679, rs766287987, and rs3734091 significantly increased the levels of AFB1-DNA adducts. Furthermore, XRCC4 GSNPs (including rs28383151, rs766287987, and rs3734091) also increased cumulative hazard for patients with HCC. These results suggest that the liver toxicity of AFB1 may be modified by XRCC4 GSNPs
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