Characterizing AGB stars in Wide-field Infrared Survey Explorer (WISE) bands

Since asymptotic giant branch (AGB) stars are bright and extended infrared objects, most Galactic AGB stars saturate the Wide-field Infrared Survey Explorer (WISE) detectors and therefore the WISE magnitudes that are restored by applying point-spread-function fitting need to be verified. Statistical properties of circumstellar envelopes around AGB stars are discussed on the basis of a WISE AGB catalog verified in this way. We cross-matched an AGB star sample with the WISE All-Sky Source Catalog and the Two Mircon All Sky Survey catalog. Infrared Space Observatory (ISO) spectra of a subsample of WISE AGB stars were also exploited. The dust radiation transfer code DUSTY was used to help predict the magnitudes in the W1 and W2 bands, the two WISE bands most affected by saturation, for calibration purpose, and to provide physical parameters of the AGB sample stars for analysis. DUSTY is verified against the ISO spectra to be a good tool to reproduce the spectral energy distributions of these AGB stars. Systematic magnitude-dependent offsets have been identified in WISE W1 and W2 magnitudes of the saturated AGB stars, and empirical calibration formulas are obtained for them on the basis of 1877 (W1) and 1558 (W2) AGB stars that are successfully fit with DUSTY. According to the calibration formulae, the corrections for W1 at 5 mag and W2 at 4 mag are $-0.383$ and 0.217 mag, respectively. In total, we calibrated the W1/W2 magnitudes of 2390/2021 AGB stars. The model parameters from the DUSTY and the calibrated WISE W1 and W2 magnitudes are used to discuss the behavior of the WISE color-color diagrams of AGB stars. The model parameters also reveal that O-rich AGB stars with opaque circumstellar envelopes are much rarer than opaque C-rich AGB stars toward the anti-Galactic center direction, which we attribute to the metallicity gradient of our Galaxy.Comment: 9 pages in two column format, 7 figures, accepted for publication in A&

Collaborative Deep Reinforcement Learning for Joint Object Search

We examine the problem of joint top-down active search of multiple objects under interaction, e.g., person riding a bicycle, cups held by the table, etc.. Such objects under interaction often can provide contextual cues to each other to facilitate more efficient search. By treating each detector as an agent, we present the first collaborative multi-agent deep reinforcement learning algorithm to learn the optimal policy for joint active object localization, which effectively exploits such beneficial contextual information. We learn inter-agent communication through cross connections with gates between the Q-networks, which is facilitated by a novel multi-agent deep Q-learning algorithm with joint exploitation sampling. We verify our proposed method on multiple object detection benchmarks. Not only does our model help to improve the performance of state-of-the-art active localization models, it also reveals interesting co-detection patterns that are intuitively interpretable

An constructive proof for the Umemura polynomials for the third Painlev\'e equation

We are concerned with the Umemura polynomials associated with the third Painlev\'e equation. We extend Taneda's method, which was developed for the Yablonskii--Vorob'ev polynomials associated with the second Painlev\'e equation, to give an algebraic proof that the rational functions generated by the nonlinear recurrence relation satisfied by Umemura polynomials are indeed polynomials. Our proof is constructive and gives information about the roots of the Umemura polynomials.Comment: 20 pages, 3 figure

Dichloropalladium complexes ligated by 4,5-bis(arylimino)pyrenylidenes: Synthesis, characterization, and catalytic behavior towards Heck-reaction

A series of 4,5-bis(arylimino)pyrenylidenylpalladium(II) chloride complexes (C1–C4) were synthesized and characterized by FT-IR and NMR spectroscopy, elemental analysis as well as by single crystal X-ray diffraction for the representative complexes C1 and C3, which revealed a square planar geometry at the palladium center. All palladium complexes exhibited high activity for the Heck cross-coupling reaction, which were effective when conducted in various solvents. Furthermore, the in-situ mixture of palladium dichloride and the ligand (L1) provided an effective catalytic system for the Heck-reaction

Two-Dimensional Topological Insulator State and Topological Phase Transition in Bilayer Graphene

We show that gated bilayer graphene hosts a strong topological insulator (TI) phase in the presence of Rashba spin-orbit (SO) coupling. We find that gated bilayer graphene under preserved time-reversal symmetry is a quantum valley Hall insulator for small Rashba SO coupling $\lambda_{\mathrm{R}}$, and transitions to a strong TI when $\lambda_{\mathrm{R}} > \sqrt{U^2+t_\bot^2}$, where $U$ and $t_\bot$ are respectively the interlayer potential and tunneling energy. Different from a conventional quantum spin Hall state, the edge modes of our strong TI phase exhibit both spin and valley filtering, and thus share the properties of both quantum spin Hall and quantum valley Hall insulators. The strong TI phase remains robust in the presence of weak graphene intrinsic SO coupling.Comment: 5 pages and 4 figure

Topological phases in gated bilayer graphene: Effects of Rashba spin-orbit coupling and exchange field

We present a systematic study on the influence of Rashba spin-orbit coupling, interlayer potential difference and exchange field on the topological properties of bilayer graphene. In the presence of only Rashba spin-orbit coupling and interlayer potential difference, the band gap opening due to broken out-of-plane inversion symmetry offers new possibilities of realizing tunable topological phase transitions by varying an external gate voltage. We find a two-dimensional $Z_2$ topological insulator phase and a quantum valley Hall phase in $AB$-stacked bilayer graphene and obtain their effective low-energy Hamiltonians near the Dirac points. For $AA$ stacking, we do not find any topological insulator phase in the presence of large Rashba spin-orbit coupling. When the exchange field is also turned on, the bilayer system exhibits a rich variety of topological phases including a quantum anomalous Hall phase, and we obtain the phase diagram as a function of the Rashba spin-orbit coupling, interlayer potential difference, and exchange field.Comment: 15 pages, 17figures, and 1 tabl

Centrality and Transverse momentum dependencies of Hadrons in Xe+Xe collisions at sNN=5.44\sqrt{s_{NN}}=5.44 TeV from a multi-phase transport model

In this paper, we study and predict the charged-particle pseudorapidity multiplicity density ($\frac{dN_{ch}}{d\eta}$), transverse momentum spectra of identified particles and their ratios in relativistic heavy ion collisions at the Large Hadron Collider (LHC), using the string-melting version of a multi-phase transport (AMPT) model with improved quark coalescence method. Results of the charged-particle pseudorapidity multiplicity density from AMPT model calculations for Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV are compared with the experimental data. Good agreements are generally found between theoretical calculations and experimental data. We predict $\frac{dN_{ch}}{d\eta}$ for Xe+Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV at different centralities, and $p_T$ spectra of charged pions, kaons and protons, and their ratios $K/\pi$ and $p/\pi$ in Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV and Xe+Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV that are being studied at LHC. The $p_T$ spectra of identified particles in Pb+Pb collisions from the improved AMPT model are compared and found to be consistent with results from the iEBE-VISHNU hybrid model with TRENTo initial condition.Comment: 6 pages, 5 figure