NeIII/OII as an oxygen abundance indicator in the HII regions and HII galaxies

To calibrate the relationship between Ne3O2 (Ne3O2 = log(\neiii$\lambda3869$/\oii$\lambda3727$)) and oxygen abundances, we present a sample of $\sim$3000 \hii galaxies from the Sloan Digital Sky Survey (SDSS) data release four. They are associated with a sample from the literature intended to enlarge the oxygen abundance region. We calculated the electron temperatures ($T_e$) of 210 galaxies in the SDSS sample with the direct method, and $T_e$ of the other 2960 galaxies in SDSS sample calculated with an empirical method. Then, we use a linear least-square fitting to calibrate the Ne3O2 oxygen abundance indicator. It is found that the Ne3O2 estimator follows a linear relation with \zoh\ that holds for the whole abundance range covered by the sample, from approximately 7.0 to 9.0. The best linear relationship between the Ne3O2 and the oxygen abundance is calibrated. The dispersion between oxygen abundance and Ne3O2 index in the metal rich galaxies may come partly from the moderate depletion of oxygen onto grains. The $Ne3O2$ method has the virtue of being single-valued and not affected by internal reddening. As a result, the $Ne3O2$ method can be a good metallicity indicator in the \hii regions and \hii galaxies, especially in high-redshift galaxies.Comment: 7 pages, 6 figures. A&A accepte

An agent-based DDM for high level architecture

The Data Distribution Management (DDM) service is one of the six services provided in the Runtime Infrastructure (RTI) of High Level Architecture (HLA). Its purpose is to perform data filtering and reduce irrelevant data communicated between federates. The two DDM schemes proposed for RTI, region based and grid based DDM, are oriented to send as little irrelevant data to subscribers as possible, but only manage to filter part of this information and some irrelevant data is still being communicated. Previously (G. Tan et al., 2000), we employed intelligent agents to perform data filtering in HLA, implemented an agent based DDM in RTI (ARTI) and compared it with the other two filtering mechanisms. The paper reports on additional experiments, results and analysis using two scenarios: the AWACS sensing aircraft simulation and the air traffic control simulation scenario. Experimental results show that compared with other mechanisms, the agent based approach communicates only relevant data and minimizes network communication, and is also comparable in terms of time efficiency. Some guidelines on when the agent based scheme can be used are also give

The Luminosity - E_p Relation within Gamma--Ray Bursts and Implications for Fireball Models

Using a sample of 2408 time-resolved spectra for 91 BATSE gamma-ray bursts (GRBs) presented by Preece et al., we show that the relation between the isotropic-equivalent luminosity (L_iso) and the spectral peak energy (E_p) in the cosmological rest frame, L_iso \propto E_p^2, not only holds within these bursts, but also holds among these GRBs, assuming that the burst rate as a function of redshift is proportional to the star formation rate. The possible implications of this relation for the emission models of GRBs are discussed. We suggest that both the kinetic-energy-dominated internal shock model and the magnetic-dissipation-dominated external shock model can well interpret this relation. We constrain the parameters for these two models, and find that they are in a good agreement with the parameters from the fittings to the afterglow data (abridged).Comment: 3 pages plus 5 figures, emulateapj style, accepted for publication in ApJ Letter

Experimental and Numerical Investigation on Progressive Collapse Resistance of Post-tensioned Precast Concrete Beam-Column Sub-assemblages

In this paper, four 1/2 scaled precast concrete (PC) beam-column sub-assemblages with high performance connection were tested under push-down loading procedure to study the load resisting mechanism of PC frames subjected to different column removal scenarios. The parameters investigated include the location of column removal and effective prestress in tendons. The test results indicated that the failure modes of unbonded post-tensioned precast concrete (PTPC) frames were different from that of reinforced concrete (RC) frames: no cracks formed in the beams and wide opening formed near the beam to column interfaces. For specimens without overhanging beams, the failure of side column was eccentric compression failure. Moreover, the load resisting mechanisms in PC frames were significantly different from that of RC frames: the compressive arch action (CAA) developed in concrete during column removal was mainly due to actively applied pre-compressive stress in the concrete; CAA will not vanish when severe crush in concrete occurred. Thus, it may provide negative contribution for load resistance when the displacement exceeds one-beam depth; the tensile force developed in the tendons could provide catenary action from the beginning of the test. Moreover, to deeper understand the behavior of tested specimens, numerical analyses were carried out. The effects of concrete strength, axial compression ratio at side columns, and loading approaches on the behavior of the sub-assemblages were also investigated based on validated numerical analysis

The chemical composition of a mild barium star HD202109

We present the result of chemical abundances of a mild barium star HD202109 (zeta Cyg) determined from the analysis of spectrum obtained by using a 2-m telescope at the Peak Terskol Observatory and a high-resolution spectrometer with R=80,000, signal to noise ratio >100. We also present the atmospheric parameters of the star determined by using various methods including iron-line abundance analysis. For line identifications, we use whole-range synthetic spectra computed by using the Kurucz database and the latest lists of spectral lines. Among the determined abundances of 51 elements, those of P, S, K, Cu, Zn, Ge, Rb, Sr, Nb, Mo, Ru, Rh, Pd, In, Sm, Gd, Tb, Dy, Er, Tm, Hf, Os, Ir, Pt, Tl, and Pb have not been previously known. Under the assumption that the overabundance pattern of Ba stars is due to wind-accretion process, adding information of more element abundances enables one to show that the heavy element overabundances of HD202109 can be explained with the wind accretion scenario model.Comment: 10 pages, Accepted by Astronomy and Astrophysic

De Novo Genome Sequence of "Candidatus Liberibacter solanacearum" from a Single Potato Psyllid in California.

The draft genome sequence of "Candidatus Liberibacter solanacearum" strain RSTM from a potato psyllid (Bactericera cockerelli) in California is reported here. The RSTM strain has a genome size of 1,286,787 bp, a G+C content of 35.1%, 1,211 predicted open reading frames (ORFs), and 43 RNA genes