13,273 research outputs found
Double-peaked Narrow Emission-line Galaxies in LAMOST Survey
We outline a full-scale search for galaxies exhibiting double-peaked profiles
of promi- nent narrow emission lines, motivated by the prospect of finding
objects related to merging galaxies, and even dual active galactic nuclei
candidates as by-product, from the Large Sky Area Multi-object Fiber
Spectroscopic Telescope (LAMOST) Data Re- lease 4. We assemble a large sample
of 325 candidates with double-peaked or strong asymmetric narrow emission
lines, with 33 objects therein appearing optically resolved dual-cored
structures, close companions or signs of recent interaction on the Sloan Dig-
ital Sky Survey images. A candidate from LAMOST (J074810.95+281349.2) is also
stressed here based on the kinematic and spatial decompositions of the
double-peaked narrow emission line target, with analysis from the
cross-referenced Mapping Nearby Galaxies at the Apache Point Observatory
(MaNGA) survey datacube. MaNGA en- ables us to constrain the origin of double
peaks for these sources, and with the IFU data we infer that the most promising
origin of double-peaked profiles for LAMOST J074810.95+281349.2 is the
`Rotation Dominated + Disturbance' structure.Comment: 13 pages, 9 figures, accepted by MNRA
Swift, XMM-Newton, and NuSTAR observations of PSR J2032+4127/MT91 213
We report our recent Swift, NuSTAR, and XMM-Newton X-ray and Lijiang optical
observations on PSR J2032+4127/MT91 213, the gamma-ray binary candidate with a
period of 45-50 years. The coming periastron of the system was predicted to be
in November 2017, around which high-energy flares from keV to TeV are expected.
Recent studies with Chandra and Swift X-ray observations taken in 2015/16
showed that its X-ray emission has been brighter by a factors of ~10 than that
before 2013, probably revealing some on-going activities between the pulsar
wind and the stellar wind. Our new Swift/XRT lightcurve shows no strong
evidence of a single vigorous brightening trend, but rather several strong
X-ray flares on weekly to monthly timescales with a slowly brightening
baseline, namely the low state. The NuSTAR and XMM-Newton observations taken
during the flaring and the low states, respectively, show a denser environment
and a softer power-law index during the flaring state, implying that the pulsar
wind interacted with stronger stellar winds of the companion to produce the
flares. These precursors would be crucial in studying the predicted giant
outburst from this extreme gamma-ray binary during the periastron passage in
late 2017.Comment: 6 pages, including 3 figures and 2 tables. Accepted for publication
in Ap
Aberrant posterior cingulate connectivity classify first-episode schizophrenia from controls: A machine learning study
Background Posterior cingulate cortex (PCC) is a key aspect of the default mode network (DMN). Aberrant PCC functional connectivity (FC) is implicated in schizophrenia, but the potential for PCC related changes as biological classifier of schizophrenia has not yet been evaluated. Methods We conducted a data-driven approach using resting-state functional MRI data to explore differences in PCC-based region- and voxel-wise FC patterns, to distinguish between patients with first-episode schizophrenia (FES) and demographically matched healthy controls (HC). Discriminative PCC FCs were selected via false discovery rate estimation. A gradient boosting classifier was trained and validated based on 100 FES vs. 93 HC. Subsequently, classification models were tested in an independent dataset of 87 FES patients and 80 HC using resting-state data acquired on a different MRI scanner. Results Patients with FES had reduced connectivity between PCC and frontal areas, left parahippocampal regions, left anterior cingulate cortex, and right inferior parietal lobule, but hyperconnectivity with left lateral temporal regions. Predictive voxel-wise clusters were similar to region-wise selected brain areas functionally connected with PCC in relation to discriminating FES from HC subject categories. Region-wise analysis of FCs yielded a relatively high predictive level for schizophrenia, with an average accuracy of 72.28% in the independent samples, while selected voxel-wise connectivity yielded an accuracy of 68.72%. Conclusion FES exhibited a pattern of both increased and decreased PCC-based connectivity, but was related to predominant hypoconnectivity between PCC and brain areas associated with DMN, that may be a useful differential feature revealing underpinnings of neuropathophysiology for schizophrenia
HySIA: Tool for Simulating and Monitoring Hybrid Automata Based on Interval Analysis
We present HySIA: a reliable runtime verification tool for nonlinear hybrid
automata (HA) and signal temporal logic (STL) properties. HySIA simulates an HA
with interval analysis techniques so that a trajectory is enclosed sharply
within a set of intervals. Then, HySIA computes whether the simulated
trajectory satisfies a given STL property; the computation is performed again
with interval analysis to achieve reliability. Simulation and verification
using HySIA are demonstrated through several example HA and STL formulas.Comment: Appeared in RV'17; the final publication is available at Springe
One-loop Neutron Electric Dipole Moment from Supersymmetry without R-parity
We present a detailed analysis together with exact numerical calculations on
one-loop contributions to neutron electric dipole moment from supersymmetry
without R-parity, focusing on the gluino, chargino, and neutralino
contributions. Apart from the neglected family mixing among quarks, complete
formulae are given for the various contributions, through the quark dipole
operators, to which the present study is restricted. We discuss the structure
and main features of the R-parity violating contributions and the interplay
between the R-parity conserving and violating parameters. In particular, the
parameter combination , under the optimal
parametrization adopted, is shown to be solely responsible for the R-parity
violating contributions in the supersymmetric loop diagrams. While
could bear a complex phase, the latter is not
necessary to have a R-parity violating contribution.Comment: 43 pages Revtex with 15 eps- and 4 ps- figure files incoporated;
proofread version to be published in Phys. Rev.
Unconventional phonon-mediated superconductivity in MgB_{2}
We have evaluated the total carrier mass enhancement factor f_{t} for MgB_{2}
from two independent experiments (specific heat and upper critical field).
These experiments consistently show that f_{t} = 3.1\pm0.1. The unusually large
f_{t} is incompatible with the measured reduced gap (2\Delta (0)/k_{B}T_{c} =
4.1) and the total isotope-effect exponent (\alpha = 0.28\pm0.04) within the
conventional phonon-mediated model. We propose an unconventional
phonon-mediated mechanism, which is able to quantitatively explain the values
of T_{c}, f_{t}, \alpha, and the reduced energy gap in a consistent way.Comment: 4 pages, 1 figure
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