820 research outputs found
The central engines of two unusual radio-intermediate/quiet active galactic nuclei: III Zw 2 and PG 1407+265
We use the accretion disk/corona+jet model to fit the multi-band spectral
energy distributions (SEDs) of two unusual radio-intermediate/quiet quasars. It
is found that the optical/UV emission of III Zw 2 is probably dominated by the
emission from the accretion disk. The X-ray emission should be dominated by the
radiation from the jet, while the contribution of the disk corona is
negligible. The optical/UV component in the SED of PG 1407+265 can be well
modeled as the emission from the accretion disk, while the IR component is
attributed to the thermal radiation from the dust torus with an opening angle ~
50\circ. If the X-ray continuum emission is dominated by the synchrotron
emission of the jet, the source should be a "high peak frequency blazar", which
obviously deviates the normal blazar sequence. The observed SED can also be
fitted quite well by the accretion disk/corona model with the viscosity
parameter ? = 0:5. The spectrum of the accretion disk/corona in PG 1407+265
satisfies the weak line quasar criterion suggested in Laor & Davis.Comment: 26 pages, 5 figures, Accepted by Ap
Perceive, Excavate and Purify: A Novel Object Mining Framework for Instance Segmentation
Recently, instance segmentation has made great progress with the rapid
development of deep neural networks. However, there still exist two main
challenges including discovering indistinguishable objects and modeling the
relationship between instances. To deal with these difficulties, we propose a
novel object mining framework for instance segmentation. In this framework, we
first introduce the semantics perceiving subnetwork to capture pixels that may
belong to an obvious instance from the bottom up. Then, we propose an object
excavating mechanism to discover indistinguishable objects. In the mechanism,
preliminary perceived semantics are regarded as original instances with
classifications and locations, and then indistinguishable objects around these
original instances are mined, which ensures that hard objects are fully
excavated. Next, an instance purifying strategy is put forward to model the
relationship between instances, which pulls the similar instances close and
pushes away different instances to keep intra-instance similarity and
inter-instance discrimination. In this manner, the same objects are combined as
the one instance and different objects are distinguished as independent
instances. Extensive experiments on the COCO dataset show that the proposed
approach outperforms state-of-the-art methods, which validates the
effectiveness of the proposed object mining framework.Comment: Accepted by CVPR Workshops 202
Truncated eigenvalue equation and long wavelength behavior of lattice gauge theory
We review our new method, which might be the most direct and efficient way
for approaching the continuum physics from Hamiltonian lattice gauge theory. It
consists of solving the eigenvalue equation with a truncation scheme preserving
the continuum limit. The efficiency has been confirmed by the observations of
the scaling behaviors for the long wavelength vacuum wave functions and mass
gaps in (2+1)-dimensional models and (1+1)-dimensional model even at
very low truncation orders. Most of these results show rapid convergence to the
available Monte Carlo data, ensuring the reliability of our method.Comment: Latex file, 4 pages, plus 4 figures encoded with uufile
Colloidal toxic trace metals in urban riverine and estuarine waters of Yantai City, southern coast of North Yellow Sea
The environmental characteristics of colloidal toxic trace metals Cd, Cu and Pb in riverine and estuarine waters collected from two urban rivers of Yantai City in eastern China, the Guangdang and Xin'an Rivers, were investigated using a modified centrifugal ultrafiltration (CUF) method in conjunction with acid extraction and inductively coupled plasma mass spectrometry. The target metals in dissolved pool were divided into four CUF fractions, i.e. <1 kDa, 1-3 kDa, 3-10 kDa and 10 kDa-0.2 mu m, and the results showed that colloidal Cd, Cu and Pb were dominated by 1-10 kDa (1-3 and 3-10 kDa), 1-3 kDa and 10 kDa-0.2 lm fractions, respectively. The coagulation/flocculation of low-molecular-weight (1-10 kDa) colloidal Cd and Cu in the estuaries was obvious and strong, while the enrichment of dissolved Pb in the 10 kDa-0.2 lm fraction may be mainly related to its biogeochemical interactions with Fe-oxides, which is easy to occur in macromolecular colloids. In addition, the actual molecular weight cutoffs (MWCOs) of the three used CUF units with nominal MWCOs of 1, 3 and 10 kDa were determined to be 4.9, 8.5 and 33.9 kDa, respectively, indicating that membrane calibration is essential for explaining the actual fraction of dissolved trace metals and verifying the integrity of ultrafiltration membrane. Overall, the results in this study provide a further understanding of the heterogeneity in biogeochemical features, migration and fate of toxic trace metals in aquatic ecosystems, especially that of the river-sea mixing zone. (C) 2019 Elsevier B.V. All rights reserved
- …