VLT near-infrared spectra of hard serendipitous Chandra sources

We present near-infrared long-slit spectra of eight optically-dim X-ray sources obtained with ISAAC on the Very Large Telescope. Six of the sources have hard X-ray emission with a significant fraction of the counts emerging above 2 keV. All were discovered serendipitously in the fields of three nearby galaxy clusters observed with Chandra, and identified through near-infrared imaging. The X-ray fluxes lie close to the break in the source counts. Two of the sources show narrow emission lines, and a third has a broad line. One of the narrow line-emitting sources has a clear redshift identification at z=2.18, while the other has a tentative determination based on the highest redshift detection of He I 10830 at z=1.26. The remainder have featureless spectra to deep limiting equivalent widths of 20--60 angstroms and line flux approx= 5 x 10^{-17} erg/s/cm^2 in the K-band. High-quality J, H and Ks--band images of the sources were combined with archival optical detections or limits to estimate a photometric redshift for six. Two sources show complex double morphology. The hard sources have spectral count ratios consistent with heavily obscured AGN, while the host galaxy emits much of the optical and near-infrared flux. The most likely explanation for the featureless continua is that the line photons are being scattered or destroyed by optically-thick gas and associated dust with large covering fractions.Comment: Replaced in response to problems with the PDF version of Fig 4 at arxiv.org, but not at the mirror sites (lanl.gov, soton.ac.uk). No content change

Synthesis of bulk, dense, nanocrystalline yttrium aluminum garnet from amorphous powders

Amorphous powders of Al2O3x2014;37.5 mol% Y2O3 (yttrium aluminum garnet (YAG)) were prepared by coprecipitation, decomposed at 800xB0;C, and hot-pressed uniaxally at low temperature (600xB0;C) and a moderate pressure (750 MPa). Optimum conditions yielded microstructures with only 2% porosity and partial crystallization of YAG. Further processing using high quasi-hydrostatic pressure (1 GPa) at 1000xB0;C enabled the production of fully crystallized YAG with gt;96% relative density and a nanocrystalline grain size of x223C;70 nm. 13

The subarcsecond mid-infrared view of local active galactic nuclei: II. The mid-infrared--X-ray correlation

We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on the high angular resolution 12 and 18um continuum fluxes from the AGN subarcsecond MIR atlas and 2-10 keV and 14-195 keV data collected from the literature. We isolate a sample of 152 objects with reliable AGN nature and multi-epoch X-ray data and minimal MIR contribution from star formation. Although the sample is not homogeneous or complete, we show that our results are unlikely to be affected by biases. The MIR--X-ray correlation is nearly linear and within a factor of two independent of the AGN type and the wavebands used. The observed scatter is <0.4 dex. A possible flattening of the correlation slope at the highest luminosities probed (~ 10^45 erg/s) is indicated but not significant. Unobscured objects have, on average, an MIR--X-ray ratio that is only <= 0.15 dex higher than that of obscured objects. Objects with intermediate X-ray column densities (22 < log N_H < 23) actually show the highest MIR--X-ray ratio on average. Radio-loud objects show a higher mean MIR--X-ray ratio at low luminosities, while the ratio is lower than average at high luminosities. This may be explained by synchrotron emission from the jet contributing to the MIR at low-luminosities and additional X-ray emission at high luminosities. True Seyfert 2 candidates and double AGN do not show any deviation from the general behaviour. Finally, we show that the MIR--X-ray correlation can be used to verify the AGN nature of uncertain objects. Specifically, we give equations that allow to determine the intrinsic 2-10 keV luminosities and column densities for objects with complex X-ray properties to within 0.34 dex. These techniques are applied to the uncertain objects of the remaining AGN MIR atlas, demonstrating the usefulness of the MIR--X-ray correlation as an empirical tool.Comment: Accepted for publication in MNRAS, 40 pages, 25 figure

Embedded AGN and star formation in the central 80 pc of IC 3639

[Abridged] Methods: We use interferometric observations in the $N$-band with VLTI/MIDI to resolve the mid-IR nucleus of IC 3639. The origin of the nuclear infrared emission is determined from: 1) the comparison of the correlated fluxes from VLTI/MIDI with the fluxes measured at subarcsec resolution (VLT/VISIR, VLT/ISAAC); 2) diagnostics based on IR fine-structure line ratios, the IR continuum emission, IR bands produced by polycyclic aromatic hydrocarbons (PAH) and silicates; and 3) the high-angular resolution spectral energy distribution. Results: The unresolved flux of IC 3639 is $90 \pm 20\, \rm{mJy}$ at $10.5\, \rm{\mu m}$, measured with three different baselines in VLTI (UT1-UT2, UT3-UT4, and UT2-UT3; $46$-$58\, \rm{m}$), making this the faintest measurement so far achieved with mid-IR interferometry. The correlated flux is a factor of $3$-$4$ times fainter than the VLT/VISIR total flux measurement. The observations suggest that most of the mid-IR emission has its origin on spatial scales between $10$ and $80\, \rm{pc}$ ($40$-$340\, \rm{mas}$). A composite scenario where the star formation component dominates over the AGN is favoured by the diagnostics based on ratios of IR fine-structure emission lines, the shape of the IR continuum, and the PAH and silicate bands. Conclusions: A composite AGN-starburst scenario is able to explain both the mid-IR brightness distribution and the IR spectral properties observed in the nucleus of IC 3639. The nuclear starburst would dominate the mid-IR emission and the ionisation of low-excitation lines (e.g. [NeII]$_{12.8 \rm{\mu m}}$) with a net contribution of $\sim 70\%$. The AGN accounts for the remaining $\sim 30\%$ of the mid-IR flux, ascribed to the unresolved component in the MIDI observations, and the ionisation of high-excitation lines (e.g. [NeV]$_{14.3 \rm{\mu m}}$ and [OIV]$_{25.9 \rm{\mu m}}$).Comment: Accepted for publication in A&

Pеngаruh Kepemilikan Manajerial, Debt To Equity Ratio dan Assets Growth terhadap Dividen Payout Ratio (Studi pada Perusahaan Lq - 45 yang Terdaftar di Bursa Efek Indonesia Periode 2012-2015)

The main objective of an investor in investing a capital that as usually the form of cash into a company is to get the expected income, dividend yield, then return and income from the dispute between the selling price of shares toward the purchase price of shares. This experimentation is aimed to determine the influence of independent variables consist of insider ownership (X1), debt to equity ratio (X2) and assets growth (X3) partially and concurrently to dependent variable dividend payout ratio (Y). This variety of experimentation is supplementary experimentation. The populations are taken from LQ-45 index company which is catalogued in Indonesia Stock Exchange 2012-2015 period and obtained 14 companies for sample selected based on certain criteria and adjusted for the purpose of research. The method used in this research is multiple linear regression model. The results of this experimentation prove that: the Dividend Payout Ratio: 1) Insider Ownership, Debt to Equity Ratio and Assets Growth concurrently have momentous influence towards Dividend Payout Ratio; 2) Insider Ownership partially has no momentous influence towards Dividend Payout Ratio; 3) Debt to Equity Ratio and Assets Growth partially have momentous influence towards Dividend Payout Ratio. Keywords: Insider Ownership, Debt to Equity Ratio, Assets Growth, Dividend Payout Ratio, Dividend Yield. АBSTRАK Tujuаn utаmа sеоrаng іnvеstоr dаlаm mеnаnаmkаn suаtu mоdаl yаng bіаsаnyа bеrbеntuk dаnа cаsh kе dаlаm suаtu pеrusаhааn аdаlаh untuk mеndаpаtkаn pеnghаsіlаn yаng dііngіnkаn, pеnghаsіlаn dаrі sеlіsіh аntаrа hаrgа juаl sаhаm tеrhаdаp hаrgа bеlі sаhаm (cаpіtаl gаіn) kеmudіаn rеturn dаn іngіn mеndаpаtkаn pеmbаgіаn dіvіdеn (dіvіdеn yіеld). Pеnеlіtіаn іnі bеrtujuаn untuk mеngеtаhuі pеngаruh dаrі vаrіаbеl іndеpеndеn yаng tеrdіrі dаrі kеpеmіlіkаn mаnаjеrіаl (X1), dеbt tо еquіty rаtіо (X2) dаn аssеts grоwth (X3) sеcаrа sіmultаn mаupun pаrsіаl tеrhаdаp vаrіаbеl tеrіkаt yаіtu dіvіdеn pаyоut rаtіо (Y). Jеnіs pеnеlіtіаn іnі аdаlаh pеnеlіtіаn pеnjеlаsаn dаn dеskrіptіf. Pоpulаsі pеrusаhааn yаng dіаmbіl dаrі pеnеlіtіаn іnі аdаlаh pеrusаhааn іndеks LQ-45 yаng tеrdаftаr dі Bursа Еfеk Іndоnеsіа Pеrіоdе 2012-2015 dаn dіdаpаtkаn sеbаnyаk 14 pеrusаhааn sаmpеl yаng tеrpіlіh bеrdаsаrkаn krіtеrіа yаng dіаmbіl dаn dіsеsuаіkаn dеngаn tujuаn pеnеlіtіаn. Mеtоdе yаng dіgunаkаn dаlаm pеnеlіtіаn іnі аdаlаh mоdеl rеgrеsі lіnеаr bеrgаndа. Hаsіl pеnеlіtіаn іnі mеmbuktіkаn bаhwа pаdа Dіvіdеn Pаyоut Rаtіо : 1) Kеpеmіlіkаn Mаnаjеrіаl, Dеbt tо Еquіty Rаtіо dаn Аssеts Grоwth sеcаrа sіmultаn bеrpеngаruh sіgnіfіkаn tеrhаdаp Dіvіdеn Pаyоut Rаtіо; 2) Kеpеmіlіkаn Mаnаjеrіаl sеcаrа pаrsіаl tіdаk bеrpеngаruh sіgnіfіkаn tеrhаdаp Dіvіdеn Pаyоut Rаtіо; 3) Dеbt tо Еquіty Rаtіо dаn Аssеts Grоwth sеcаrа pаrsіаl bеrpеngаruh sіgnіfіkаn tеrhаdаp Dіvіdеn Pаyоut Rаtіо. Kаtа Kuncі : Kеpеmіlіkаn Mаnаjеr, Dеbt tо Еquіty Rаtіо, Аssеts Grоwth, Dіvіdеn Pаyоut Rаtіо, DіvіdеnYіеld

Expanding hot flow in the black hole binary SWIFT J1753.5-0127: evidence from optical timing

We describe the evolution of optical and X-ray temporal characteristics during the outburst decline of the black hole X-ray binary SWIFT J1753.5-0127. The optical/X-ray cross-correlation function demonstrates a single positive correlation at the outburst peak, then it has multiple dips and peaks during the decline stage, which are then replaced by the precognition dip plus peak structure in the outburst tail. Power spectral densities and phase lags show a complex evolution, revealing the presence of intrinsically connected optical and X-ray quasi-periodic oscillations. For the first time, we quantitatively explain the evolution of these timing properties during the entire outburst within one model, the essence of which is the expansion of the hot accretion flow towards the tail of the outburst. The pivoting of the spectrum produced by synchrotron Comptonization in the hot flow is responsible for the appearance of the anti-correlation with the X-rays and for the optical quasi-periodic oscillations. Our model reproduces well the cross-correlation and phase lag spectrum during the decline stage, which could not be understood with any model proposed before.Comment: 13 pages, 11 figures, MNRAS submitte

Dopamine protects neurons against glutamate-induced excitotoxicity

Glutamate excitotoxicity is responsible for neuronal death in acute neurological disorders including stroke, trauma and neurodegenerative disease. Loss of calcium homeostasis is a key mediator of glutamate-induced cell death. The neurotransmitter dopamine (DA) is known to modulate calcium signalling, and here we show that it can do so in response to physiological concentrations of glutamate. Furthermore, DA is able to protect neurons from glutamate-induced cell death at pathological concentrations of glutamate. We demonstrate that DA has a novel role in preventing delayed calcium deregulation in cortical, hippocampal and midbrain neurons. The effect of DA in abolishing glutamate excitotoxicity can be induced by DA receptor agonists, and is abolished by DA receptor antagonists. Our data indicate that the modulation of glutamate excitotoxicity by DA is receptor-mediated. We postulate that DA has a major physiological function as a safety catch to restrict the glutamate-induced calcium signal, and thereby prevent glutamate-induced cell death in the brain

Optical and near-infrared observations of hard serendipitous Chandra sources

We have been carrying out a successful observational programme targeted at finding the highly obscured quasars that are thought to be the main contributors to the hard X-ray background. Out of 56 sources so far studied with optical and near-infrared imaging and spectroscopy, we have found three definite and a further twelve possible Type II quasars. Few sources show significant line emission, suggesting that the line photons are depleted by the large columns of obscuring matter. The redshift distribution of our sources shows a distinct peak at z~1. The broad-band colours and magnitudes of the optical/near-infrared counterparts indicate that the light in these bands is dominated by the continuum of a massive bright galaxy.Comment: Astron. Nachr. in press, issue dedicated to the proceedings of the workshop "X-ray Surveys in the light of New Observatories", Sep. 2002, Santander, Spai

Fish culture in marine farm at Mandapam

The large-scale monoculture and polyculture of the milkfish, Chanos chanos were reported earlier form Southeast Asian countries.This article highlights some interesting and encouraging results obtained during the experiments of milkfish monoculture and polyculture of milkfish with mullet in Mandapam ponds. In the monoculture of milkfish the average size of the fish as well as the production rate could be substantially stepped up by resorting to supplementary feeding. In the polyculture of milkfish, the average growth rate was found to be more or less similar in both the fertilized and unfertilized ponds but the survival and production rates were higher in unfertilized pond. The yield of milkfish under monoculture in the present study is comparable to that of Ceylon, where selective harvesting followed by replenishment gave a production of 799 to 1159 kg/ha/annum. A production rate of 1405 kg/ha/10 months obtained in the present experimental polyculture of milkfish