4,735 research outputs found
The Hard X-Ray View of Reflection, Absorption, and the Disk-Jet Connection in the Radio-Loud AGN 3C 33
We present results from Suzaku and Swift observations of the nearby radio
galaxy 3C 33, and investigate the nature of absorption, reflection, and jet
production in this source. We model the 0.5-100 keV nuclear continuum with a
power law that is transmitted either through one or more layers of pc-scale
neutral material, or through a modestly ionized pc-scale obscurer. The standard
signatures of reflection from a neutral accretion disk are absent in 3C 33:
there is no evidence of a relativistically blurred Fe K emission line,
and no Compton reflection hump above 10 keV. We find the upper limit to the
neutral reflection fraction is R<0.41 for an e-folding energy of 1 GeV. We
observe a narrow, neutral Fe K line, which is likely to originate at
least 2,000 R_s from the black hole. We show that the weakness of reflection
features in 3C 33 is consistent with two interpretations: either the inner
accretion flow is highly ionized, or the black-hole spin configuration is
retrograde with respect to the accreting material.Comment: 12 pages, 11 figures, 4 tables. Accepted for publication in Ap
Adapting tissue-engineered in vitro CNS models for high-throughput study of neurodegeneration
Neurodegenerative conditions remain difficult to treat, with the continuing failure to see therapeutic research successfully advance to clinical trials. One of the obstacles that must be overcome is to develop enhanced models of disease. Tissue engineering techniques enable us to create organised artificial central nervous system tissue that has the potential to improve the drug development process. This study presents a replicable model of neurodegenerative pathology through the use of engineered neural tissue co-cultures that can incorporate cells from various sources and allow degeneration and protection of neurons to be observed easily and measured, following exposure to neurotoxic compounds - okadaic acid and 1-methyl-4-phenylpyridinium. Furthermore, the technology has been miniaturised through development of a mould with 6 mm length that recreates the advantageous features of engineered neural tissue co-cultures at a scale suitable for commercial research and development. Integration of human-derived induced pluripotent stem cells aids more accurate modelling of human diseases, creating new possibilities for engineered neural tissue co-cultures and their use in drug screening
XMM-EPIC observation of MCG-6-30-15: Direct evidence for the extraction of energy from aspinning black hole?
We present XMM-Newton European Photon Imaging Camera (EPIC) observations of
the bright Seyfert 1 galaxy MCG-6-30-15, focusing on the broad Fe K
line at ~6keV and the associated reflection continuum, which is believed to
originate from the inner accretion disk. We find these reflection features to
be extremely broad and red-shifted, indicating its origin from the very most
central regions of the accretion disk. It seems likely that we have caught this
source in the ``deep minimum'' state first observed by Iwasawa et al. (1996).
The implied central concentration of X-ray illumination is difficult to
understand in any pure accretion disk model. We suggest that we are witnessing
the extraction and dissipation of rotational energy from a spinning black hole
by magnetic fields connecting the black hole or plunging region to the disk.Comment: 6 pages and one postscript figure. Accepted for publication in MNRAS
letter
Comparison of performance achievement award recognition with primary stroke center certification for acute ischemic stroke care.
BackgroundHospital certification and recognition programs represent 2 independent but commonly used systems to distinguish hospitals, yet they have not been directly compared. This study assessed acute ischemic stroke quality of care measure conformity by hospitals receiving Primary Stroke Center (PSC) certification and those receiving the American Heart Association's Get With The Guidelines-Stroke (GWTG-Stroke) Performance Achievement Award (PAA) recognition.Methods and resultsThe patient and hospital characteristics as well as performance/quality measures for acute ischemic stroke from 1356 hospitals participating in the GWTG-Stroke Program 2010-2012 were compared. Hospitals were classified as PAA+/PSC+ (hospitals n = 410, patients n = 169,302), PAA+/PSC- (n = 415, n = 129,454), PAA-/PSC+ (n = 88, n = 26,386), and PAA-/PSC- (n = 443, n = 75,565). A comprehensive set of stroke measures were compared with adjustment for patient and hospital characteristics. Patient characteristics were similar by PAA and PSC status but PAA-/PSC- hospitals were more likely to be smaller and nonteaching. Measure conformity was highest for PAA+/PSC+ and PAA+/PSC- hospitals, intermediate for PAA-/PSC+ hospitals, and lowest for PAA-/PSC- hospitals (all-or-none care measure 91.2%, 91.2%, 84.3%, and 76.9%, respectively). After adjustment for patient and hospital characteristics, PAA+/PSC+, PAA+/PSC-, and PAA-/PSC+ hospitals had 3.15 (95% CIs 2.86 to 3.47); 3.23 (2.93 to 3.56) and 1.72 (1.47 to 2.00), higher odds for providing all indicated stroke performance measures to patients compared with PAA-/PSC- hospitals.ConclusionsWhile both PSC certification and GWTG-Stroke PAA recognition identified hospitals providing higher conformity with care measures for patients hospitalized with acute ischemic stroke, PAA recognition was a more robust identifier of hospitals with better performance
Aircraft based four-channel thermal dissociation laser induced fluorescence instrument for simultaneous measurements of NO2, total peroxy nitrate, total alkyl nitrate, and HNO3
A four-channel thermal dissociation laser induced fluorescence (TD-LIF) instrument has been developed for simultaneous measurements of nitrogen dioxide (NO2), total peroxy nitrate (âPNs), total alkyl nitrate (âANs) and nitric acid (HNO3). NO2 is measured directly by LIF at 532 nm, whereas organic nitrates and nitric acid are thermally dissociated at distinct temperatures in the inlet to form NO2, which is then measured by LIF. The concentrations of each dissociated species are derived by the differences in measured NO2 relative to the reference colder inlet channel. The TD-LIF was adapted to fly on board the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe 146-301 atmospheric research aircraft in summer 2010, and to date has successfully flown in five field campaigns. This paper reports novel improvements in the TD-LIF instrumentations, including (1) the use of a single wavelength laser, which makes the system compact and relatively cheap; (2) the use of a single beam laser that allows easy alignment and optical stability against the vibrational aircraft environment; and (3) the optical assembly of four detection cells that allow simultaneous and fast (time resolution up to 0.1 s) measurements of NO2, âPNs, âANs and HNO3. Laboratory-generated mixtures of PNs, ANs and HNO3 in zero air are converted into NO2 and used to fix the dissociation temperatures of each heated inlet to test the selectivity of the instrument and potential interferences due to recombination reactions of the dissociated products. The effectiveness of the TD-LIF was demonstrated during the RONOCO aircraft campaign (summer 2010). A chemiluminescence system that was measuring NO2 and a broadband cavity enhanced absorption spectrometer (BBCEAS) that was measuring one of the PNs (N2O5) were installed on the same aircraft during the campaign. The in-flight intercomparison of the new TD-LIF with the chemiluminescence system for NO2 measurements and the intercomparison between âPNs measured by the TD-LIF and N2O5 by the BBCEAS are used to assess the performance of the TD-LIF
Dynamic pressure enhancements as a cause of largeâscale stormtime substorms
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94960/1/jgra19239.pd
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