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AzTEC millimetre survey of the COSMOS field – I. Data reduction and source catalogue
Scott, K. S.,Austermann, J. E.,Perera, T. A.,Wilson, G. W.,Aretxaga, I.,Bock, J. J.,Hughes, D. H.,Kang, Y.,Kim, S.,Mauskopf, P. D.,Sanders, D. B.,Scoville, N.,Yun, M. S. Blackwell Publishing Ltd 2008 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.385 No.4
<P>ABSTRACT</P><P>We present a 1.1 mm wavelength imaging survey covering 0.3 deg<SUP>2</SUP> in the COSMOS field. These data, obtained with the AzTEC continuum camera on the James Clerk Maxwell Telescope, were centred on a prominent large-scale structure overdensity which includes a rich X-ray cluster at <I>z</I>≈ 0.73. A total of 50 mm-galaxy candidates, with a significance ranging from 3.5 to 8.5σ, are extracted from the central 0.15 deg<SUP>2</SUP> area which has a uniform sensitivity of ∼1.3 mJy beam<SUP>−1</SUP>. 16 sources are detected with S/N ≥ 4.5, where the expected false-detection rate is zero, of which a surprisingly large number (9) have intrinsic (deboosted) fluxes ≥5 mJy at 1.1 mm. Assuming the emission is dominated by radiation from dust, heated by a massive population of young, optically obscured stars, then these bright AzTEC sources have far-infrared luminosities >6 × 10<SUP>12</SUP> L<SUB>⊙</SUB> and star formation rates >1100 M<SUB>⊙</SUB> yr<SUP>−1</SUP>. Two of these nine bright AzTEC sources are found towards the extreme peripheral region of the X-ray cluster, whilst the remainder are distributed across the larger scale overdensity. We describe the AzTEC data reduction pipeline, the source-extraction algorithm, and the characterization of the source catalogue, including the completeness, flux deboosting correction, false-detection rate and the source positional uncertainty, through an extensive set of Monte Carlo simulations. We conclude with a preliminary comparison, via a stacked analysis, of the overlapping MIPS 24-μm data and radio data with this AzTEC map of the COSMOS field.</P>
Julián David Salazar-Gutiérrez,Andrés Castelblanco,María Ximena Rodríguez-Bocanegrab,Wilson Teran,Adriana Sáenz-Aponte 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.4
Entomopathogenic nematodes are key players for insect pest control and constitute an environmentally friendly alternative for crop protection. The insecticidal activity of the family Heterorhabditidae relies on a tight symbiotic relationship with enterobacteria of the genus Photorhabdus, where the bacterial contribution towards the death of the host has been highlighted. In the present work, we report the identification and pathogenic characterization of Photorhabdus luminescens strain SL0708, which is the natural symbiont of Heterorhabditis indica SL0708. We evaluated the pathogenicity of whole bacterial cells and acellular extracts against both Spodoptera frugiperda larvae and Galleria mellonella. Phylogenetic analyses using a polygenic sequencing approach assigned the bacterial strain to Photorhabdus luminescens subsp. akhurstii and bioassays showed it is highly pathogenic for both insects. After 48 h of treatment with 1× 103 −1 × 104 CFU/larva, 100% mortality was attained. Furthermore, when intra- or extracellular bacterial extracts were injected into G. mellonella, a cumulative percent mortality of 63% and 100% was respectively obtained after 72 h. In contrast, a 10% and 93% mortality was achieved for S. frugiperda with intra and extracellular extracts, respectively highlighting the role of extracellular factors in pathogenicity. We detected extracellular activities potentially accounting for the high pathogenicity observed and these included; proteases, esterases, ureases, hemolysins and siderophores. Interestingly, S. frugiperda was more susceptible to P. luminescens SL0708 cells than G. mellonella, which contrasted to its higher resistance to H. indica SL0708 nematodes, which suggests that EPN biological control potential should also be evaluated based on bacterial symbiont pathogenicity
THE AzTEC/SMA INTERFEROMETRIC IMAGING SURVEY OF SUBMILLIMETER-SELECTED HIGH-REDSHIFT GALAXIES
Younger, Joshua D.,Fazio, Giovanni G.,Huang, Jia-Sheng,Yun, Min S.,Wilson, Grant W.,Ashby, Matthew L. N.,Gurwell, Mark A.,Peck, Alison B.,Petitpas, Glen R.,Wilner, David J.,Hughes, David H.,Aretxaga, IOP Publishing 2009 The Astrophysical journal Vol.704 No.1
<P>We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size similar to 2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) > 5 or peak S/N > 4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N > 4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology-including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared-of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation-which struggle to account for such objects even under liberal assumptions-and dust production models given the limited time since the big bang.</P>
An AzTEC 1.1-mm survey for ULIRGs in the field of the Galaxy Cluster MS 0451.6−0305
Wardlow, J. L.,Smail, Ian,Wilson, G. W.,Yun, M. S.,Coppin, K. E. K.,Cybulski, R.,Geach, J. E.,Ivison, R. J.,Aretxaga, I.,Austermann, J. E.,Edge, A. C.,Fazio, G. G.,Huang, J.,Hughes, D. H.,Kodama, T.,K Blackwell Publishing Ltd 2010 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.401 No.4
<P>ABSTRACT</P><P>We have undertaken a deep (σ∼ 1.1 mJy) 1.1-mm survey of the <I>z</I>= 0.54 cluster MS 0451.6−0305 using the AzTEC camera on the James Clerk Maxwell Telescope. We detect 36 sources with signal-to-noise ratio (S/N) ≥ 3.5 in the central 0.10 deg<SUP>2</SUP> and present the AzTEC map, catalogue and number counts. We identify counterparts to 18 sources (50 per cent) using radio, mid-infrared, <I>Spitzer</I> InfraRed Array Camera (IRAC) and Submillimetre Array data. Optical, near- and mid-infrared spectral energy distributions are compiled for the 14 of these galaxies with detectable counterparts, which are expected to contain all likely cluster members. We then use photometric redshifts and colour selection to separate background galaxies from potential cluster members and test the reliability of this technique using archival observations of submillimetre galaxies. We find two potential MS 0451−03 members, which, if they are both cluster galaxies, have a total star formation rate (SFR) of ∼100 M<SUB>⊙</SUB> yr<SUP>−1</SUP>– a significant fraction of the combined SFR of all the other galaxies in MS 0451−03. We also examine the stacked rest-frame mid-infrared, millimetre and radio emission of cluster members below our AzTEC detection limit, and find that the SFRs of mid-IR-selected galaxies in the cluster and redshift-matched field populations are comparable. In contrast, the average SFR of the morphologically classified late-type cluster population is nearly three times less than the corresponding redshift-matched field galaxies. This suggests that these galaxies may be in the process of being transformed on the red sequence by the cluster environment. Our survey demonstrates that although the environment of MS 0451−03 appears to suppress star formation in late-type galaxies, it can support active, dust-obscured mid-IR galaxies and potentially millimetre-detected LIRGs.</P>
The source counts of submillimetre galaxies detected at λ= 1.1 mm
Scott, K. S.,Wilson, G. W.,Aretxaga, I.,Austermann, J. E.,Chapin, E. L.,Dunlop, J. S.,Ezawa, H.,Halpern, M.,Hatsukade, B.,Hughes, D. H.,Kawabe, R.,Kim, S.,Kohno, K.,Lowenthal, J. D.,Montañ,a, A. Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.423 No.1
<P><B>ABSTRACT</B></P><P>The source counts of galaxies discovered at submillimetre and millimetre wavelengths provide important information on the evolution of infrared‐bright galaxies. We combine the data from six blank‐field surveys carried out at 1.1 mm with AzTEC, totalling 1.6 deg<SUP>2</SUP> in area with root‐mean‐square depths ranging from 0.4 to 1.7 mJy, and derive the strongest constraints to date on the 1.1 mm source counts at flux densities <I>S</I><SUB>1100</SUB>= 1–12 mJy. Using additional data from the AzTEC Cluster Environment Survey to extend the counts to <I>S</I><SUB>1100</SUB>∼ 20 mJy, we see tentative evidence for an enhancement relative to the exponential drop in the counts at <I>S</I><SUB>1100</SUB>∼ 13 mJy and a smooth connection to the bright source counts at >20 mJy measured by the South Pole Telescope; this excess may be due to strong‐lensing effects. We compare these counts to predictions from several semi‐analytical and phenomenological models and find that for most the agreement is quite good at flux densities ≳ 4 mJy; however, we find significant discrepancies (≳ 3σ) between the models and the observed 1.1‐mm counts at lower flux densities, and none of them is consistent with the observed turnover in the Euclidean‐normalized counts at <I>S</I><SUB>1100</SUB>≲ 2 mJy. Our new results therefore may require modifications to existing evolutionary models for low‐luminosity galaxies. Alternatively, the discrepancy between the measured counts at the faint end and predictions from phenomenological models could arise from limited knowledge of the spectral energy distributions of faint galaxies in the local Universe.</P>
Drilling to Gabbro in Intact Ocean Crust
Wilson, Douglas S.,Teagle, Damon A. H.,Alt, Jeffrey C.,Banerjee, Neil R.,Umino, Susumu,Miyashita, Sumio,Acton, Gary D.,Anma, Ryo,Barr, Samantha R.,Belghoul, Akram,Carlut, Julie,Christie, David M.,Cogg American Association for the Advancement of Scienc 2006 Science Vol.312 No.5776
<P>Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.</P>
Oxidation of vanillin by peroxomonosulphate-thermodynamic and kinetic investigation
S. Kutti Rani,S. Nirmal Kumar,Crystal Y. Wilson,A. Gopi,D. Easwaramoorthy 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.6
The oxidation of vanillin by peroxomonosulphate (PMS) in acetic acid–sodiumacetate bufferedmedium was carried out at 308 K. The rate was first order with respect to [vanillin] and [PMS]. The rate increased with increase in pH and the rate was too fast to be measured at pH 5.2. The rate increased with increase in [acetate] and the plot of kobs versus [acetate] was a straight line with positive intercept. Variation of ionic strength had no effect on the rate of the reaction. Effects of polarity were studied with five different solvents and in all the cases, log kobs versus 1/e were linear with negative slope. The reaction had been carried out at four different temperatures and the activation and thermodynamic parameters were calculated. The product of oxidation was confirmed as vanillic acid by IR, 1H NMR and GC-MS spectral analysis. Based on the results obtained a reaction scheme had been proposed and the rate law was derived.