5,999 research outputs found

    Carbon-13 nuclear magnetic resonance spectra and mechanism of bridge–terminal carbonyl exchange in di-µ-carbonyl-bis[carbonyl(η-cyclopentadienyl)iron](Fe–Fe)[{(η-C5H5)Fe(CO)2}2]; cd-di-µ-carbonyl-f-carbonyl-ae-di(η-cyclopentadienyl)-b-(triethyl -phosphite)di-iron(Fe–Fe)[(η-C5H5)2Fe2(CO)3P(OEt)3], and some related complexes

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    A mechanism involving carbonyl-bridge breaking, rotation about the Fe–Fe bond, and bridge reformation is shown to account qualitatively for changes in the carbonyl region of the 13C n.m.r spectrum of the complex [(cp)(OC)[graphic omitted]e(cp){P(OEt)3}] and quantitatively for [(cp)(OC)[graphic omitted]e(CO)(cp)](cp =η-cyclopentadienyl).The activation energy for this process, 49.0 ± 4 kJ mol^–1(11.7 ± 1 kcal mol^–1), is close to that reported for cis–trans-isomerization of the cp groups, in accord with this mechanism. Variable-temperature 13C n.m.r. spectra of the complexes [(cp)(OC)[graphic omitted]u(CO)(cp)] and [(cp)(OC)[graphic omitted]i(cp)] are also reported

    Blue Swimmer Crab ( Portunus armatus ) and Sand Crab ( Ovalipes australiensis ) Resource in the South Coast Bioregion of Western Australia

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    The blue swimmer crab (Portunus armatus) is found along the entire coastline of Western Australia (WA) in a range of estuarine, inshore and continental shelf areas (\u3c50 m). In the South Coast Bioregion (SCB), blue swimmer crabs are retained as by-product in commercial nets of the 25 licences operating in the South Coast Estuarine Managed Fishery (SCEMF) and targeted by purpose-designed crab traps allocated to fishers in Princess Royal and Oyster Harbours in Albany

    Blue Swimmer Crab ( Portunus armatus ) Resource in the West Coast Bioregion, Western Australia Part 2: Warnbro Sound, Comet Bay, Mandurah to Bunbury, Leschenault Estuary, Geographe Bay an d Hardy Inlet

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    Blue swimmer crabs (Portunus armatus) are found along the entire coastline of Western Australia in a range of estuarine, inshore and continental shelf environments (\u3c50 m). Crab fisheries in the West Coast Bioregion are centred in the estuaries and coastal embayments from the Swan-Canning Estuary south to Geographe Bay. Major commercial and recreational fisheries in this Bioregion include the Cockburn Sound Crab Managed Fishery, the Swan-Canning Estuary Crab Fishery (Area 1 of the West Coast Estuarine Managed Fishery), and the Peel-Harvey Crab Fishery (Area 2 of the West Coast Estuarine Managed Fishery). Refer to Johnston et al. (2020b) for detailed information on these fisheries

    Blue Swimmer Crab ( Portunus armatus ) and Mud Crab Scylla serrata and Scylla olivacea ) Resources in the North Coast and Gascoyne Coast Bioregions, Western Australia

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    Blue swimmer crab (Portunus armatus) are found along the entire Western Australia (WA) coast, in a range of estuarine, inshore and continental shelf areas (\u3c50 m). In the North Coast Bioregion (NCB), commercial fishing primarily occurs as part of the Pilbara Crab Managed Fishery (PCMF) which spans the inshore waters from Onslow through to Port Hedland, with most fishing activity taking place around Nickol Bay

    Blue Swimmer Crab ( Portunus armatus ) Resource in the West Coast Bioregion, Western Australia Part 1: Peel Harvey Estuary, Cockburn Sound and Swan Canning Estuary

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    Blue swimmer crabs (Portunus armatus) are found along the entire coastline of Western Australia in a range of estuarine, inshore and continental shelf areas (\u3c50 m). In the West Coast Bioregion (WCB), crab fisheries are centred in estuaries and coastal embayments from Geographe Bay to the Swan River. Commercial fisheries include the Cockburn Sound Crab Managed Fishery (CSCMF), the Warnbro Sound Crab Managed Fishery, the Swan-Canning Estuary (SCE) Crab Fishery (Area 1 of the West Coast Estuarine Managed Fishery (WCEMF)), Peel-Harvey Crab Fishery (Area 2 of the WCEMF), Hardy Inlet (Area 3 of the WCEMF) and the Mandurah to Bunbury Developing Crab Fishery (Area 1, Comet Bay and Area 2, Mandurah-Bunbury)

    PTF11kx: A Type Ia Supernova with Hydrogen Emission Persisting After 3.5 Years

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    The optical transient PTF11kx exhibited both the characteristic spectral features of Type Ia supernovae (SNe Ia) and the signature of ejecta interacting with circumstellar material (CSM) containing hydrogen, indicating the presence of a nondegenerate companion. We present an optical spectrum at 13421342 days after peak from Keck Observatory, in which the broad component of Hα\alpha emission persists with a similar profile as in early-time observations. We also present SpitzerSpitzer IRAC detections obtained 12371237 and 18181818 days after peak, and an upper limit from HSTHST ultraviolet imaging at 21332133 days. We interpret our late-time observations in context with published results - and reinterpret the early-time observations - in order to constrain the CSM's physical parameters and compare to theoretical predictions for recurrent nova systems. We find that the CSM's radial extent may be several times the distance between the star and the CSM's inner edge, and that the CSM column density may be two orders of magnitude lower than previous estimates. We show that the Hα\alpha luminosity decline is similar to other SNe with CSM interaction, and demonstrate how our infrared photometry is evidence for newly formed, collisionally heated dust. We create a model for PTF11kx's late-time CSM interaction and find that X-ray reprocessing by photoionization and recombination cannot reproduce the observed Hα\alpha luminosity, suggesting that the X-rays are thermalized and that Hα\alpha radiates from collisional excitation. Finally, we discuss the implications of our results regarding the progenitor scenario and the geometric properties of the CSM for the PTF11kx system.Comment: 15 pages, 8 figures, 3 tables; submitted to Ap

    Is there a correlation between infection control performance and other hospital quality measures?

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    Quality measures are increasingly reported by hospitals to the Centers for Medicare and Medicaid Services (CMS), yet there may be tradeoffs in performance between infection control (IC) and other quality measures. Hospitals that performed best on IC measures did not perform well on most CMS non–IC quality measures

    Bayesian inference of ancestral dates on bacterial phylogenetic trees

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    The sequencing and comparative analysis of a collection of bacterial genomes from a single species or lineage of interest can lead to key insights into its evolution, ecology or epidemiology. The tool of choice for such a study is often to build a phylogenetic tree, and more specifically when possible a dated phylogeny, in which the dates of all common ancestors are estimated. Here, we propose a new Bayesian methodology to construct dated phylogenies which is specifically designed for bacterial genomics. Unlike previous Bayesian methods aimed at building dated phylogenies, we consider that the phylogenetic relationships between the genomes have been previously evaluated using a standard phylogenetic method, which makes our methodology much faster and scalable. This two-step approach also allows us to directly exploit existing phylogenetic methods that detect bacterial recombination, and therefore to account for the effect of recombination in the construction of a dated phylogeny. We analysed many simulated datasets in order to benchmark the performance of our approach in a wide range of situations. Furthermore, we present applications to three different real datasets from recent bacterial genomic studies. Our methodology is implemented in a R package called BactDating which is freely available for download at https://github.com/xavierdidelot/BactDating

    Magnetic White Dwarfs from the SDSS II. The Second and Third Data Releases

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    Fifty-two magnetic white dwarfs have been identified in spectroscopic observations from the Sloan Digital Sky Survey (SDSS) obtained between mid-2002 and the end of 2004, including Data Releases 2 and 3. Though not as numerous nor as diverse as the discoveries from the first Data Release, the collection exhibits polar field strengths ranging from 1.5MG to ~1000MG, and includes two new unusual atomic DQA examples, a molecular DQ, and five stars that show hydrogen in fields above 500MG. The highest-field example, SDSSJ2346+3853, may be the most strongly magnetic white dwarf yet discovered. Analysis of the photometric data indicates that the magnetic sample spans the same temperature range as for nonmagnetic white dwarfs from the SDSS, and support is found for previous claims that magnetic white dwarfs tend to have larger masses than their nonmagnetic counterparts. A glaring exception to this trend is the apparently low-gravity object SDSSJ0933+1022, which may have a history involving a close binary companion.Comment: 20 pages, 4 figures Accepted for publication in the Astronomical Journa
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