94 research outputs found
Shocked Molecular Gas in the Supernova Remnant HB 21
We report the discovery of the shocked molecular gas in the supernova remnant
HB 21. We derive the physical parameters of the shocked gas from CO J=1-0 and
J=2-1 line observations. We discuss the correlation of the shocked molecular
gas with the previously detected, shocked atomic gas and the associated
infrared emission.Comment: 24 pages, 10 figures, To appear in the ApJ, scheduled for the April
10, 2001 issue (v551
XMM-Newton discovery of 217 s pulsations in the brightest persistent supersoft X-ray source in M31
We report on the discovery of a periodic modulation in the bright supersoft
X-ray source XMMU J004252.5+411540 detected in the 2000-2004 XMM-Newton
observations of M31. The source exhibits X-ray pulsations with a period P~217.7
s and a quasi-sinusoidal pulse shape and pulsed fraction ~7-11%. We did not
detect statistically significant changes in the pulsation period on the time
scale of 4 years. The X-ray spectra of XMMU J004252.5+411540 are extremely soft
and can be approximated with an absorbed blackbody of temperature 62-77 eV and
a weak power law tail of photon index ~1.7-3.1 in the 0.2-3.0 keV energy band.
The X-ray properties of the source and the absence of an optical/UV counterpart
brighter than 19 mag suggest that it belongs to M31. The estimated bolometric
luminosity of the source varies between ~2e38 and ~8e38 ergs/s at 760 kpc,
depending on the choice of spectral model. The X-ray pulsations and supersoft
spectrum of XMMU J004252.5+411540 imply that it is almost certainly an
accreting white dwarf, steadily burning hydrogen-rich material on its surface.
We interpret X-ray pulsations as a signature of the strong magnetic field of
the rotating white dwarf. Assuming that the X-ray source is powered by disk
accretion, we estimate its surface field strength to be in the range 4e5 G
<B_{0}<8e6 G. XMMU J004252.5+411540 is the second supersoft X-ray source in M31
showing coherent pulsations, after the transient supersoft source XMMU
J004319.4+411758 with 865.5 s pulsation period.Comment: 11 pages, 4 figures, uses emulateapj style. Submitted to Ap
The inter-rater reliability of the Risk Instrument for Screening in the Community
Predicting risk of adverse healthcare outcomes is important to enable targeted delivery of interventions. The Risk Instrument for Screening in the Community (RISC), designed for use by public health nurses (PHNs), measures the one-year risk of hospitalisation, institutionalisation and death in community-dwelling older adults according to a five-point global risk score: from low (score 1,2), medium (3) and high (4,5). We examined the inter-rater reliability (IRR) of the RISC between student PHNs (n=32) and expert raters using six cases (two low, medium and high-risk), scored before and after RISC training. Correlations increased for each adverse outcome, statistically significantly for institutionalisation (r=0.72 to 0.80,p=0.04) and hospitalisation, (r=0.51 to 0.71,p<0.01) but not death. Training improved accuracy for low-risk but not all high-risk cases. Overall, the RISC showed good IRR, which increased after RISC training. That reliability reduced for some high-risk cases suggests that the training programme requires adjustment to further improve IRR
The Optical-Near-IR Spectrum of the M87 Jet From HST Observations
We present 1998 HST observations of M87 which yield the first single-epoch
optical and radio-optical spectral index images of the jet at
resolution. We find , comparable to previous
measurements, and (),
slightly flatter than previous workers. Reasons for this discrepancy are
discussed. These observations reveal a large variety of spectral slopes. Bright
knots exhibit flatter spectra than interknot regions. The flattest spectra
(; comparable to or flatter than ) are
found in two inner jet knots (D-East and HST-1) which contain the fastest
superluminal components. In knots A, B and C, and are
essentially anti-correlated. Near the flux maxima of knots HST-1 and F, changes
in lag changes in , but in knots D and E, the opposite
relationship is observed. This is further evidence that radio and optical
emissions in the M87 jet come from substantially different physical regions.
The delays observed in the inner jet are consistent with localized particle
acceleration, with for optically emitting electrons in
knots HST-1 and F, and for optically emitting electrons
in knots D and E. Synchrotron models yield \nu_B \gsim 10^{16} Hz for knots
D, A and B, and somewhat lower values, Hz, in
other regions. If X-ray emissions from knots A, B and D are co-spatial with
optical and radio emission, we can strongly rule out the ``continuous
injection'' model. Because of the short lifetimes of X-ray synchrotron emitting
particles, the X-ray emission likely fills volumes much smaller than the
optical emission regions.Comment: Text 17 pages, 3 Tables, 11 figures, accepted by Ap
The Glycobiome of the Rumen Bacterium Butyrivibrio proteoclasticus B316T Highlights Adaptation to a Polysaccharide-Rich Environment
Determining the role of rumen microbes and their enzymes in plant polysaccharide breakdown is fundamental to understanding digestion and maximising productivity in ruminant animals. Butyrivibrio proteoclasticus B316T is a Gram-positive, butyrate-forming rumen bacterium with a key role in plant polysaccharide degradation. The 4.4Mb genome consists of 4 replicons; a chromosome, a chromid and two megaplasmids. The chromid is the smallest reported for all bacteria, and the first identified from the phylum Firmicutes. B316 devotes a large proportion of its genome to the breakdown and reassembly of complex polysaccharides and has a highly developed glycobiome when compared to other sequenced bacteria. The secretion of a range of polysaccharide-degrading enzymes which initiate the breakdown of pectin, starch and xylan, a subtilisin family protease active against plant proteins, and diverse intracellular enzymes to break down oligosaccharides constitute the degradative capability of this organism. A prominent feature of the genome is the presence of multiple gene clusters predicted to be involved in polysaccharide biosynthesis. Metabolic reconstruction reveals the absence of an identifiable gene for enolase, a conserved enzyme of the glycolytic pathway. To our knowledge this is the first report of an organism lacking an enolase. Our analysis of the B316 genome shows how one organism can contribute to the multi-organism complex that rapidly breaks down plant material in the rumen. It can be concluded that B316, and similar organisms with broad polysaccharide-degrading capability, are well suited to being early colonizers and degraders of plant polysaccharides in the rumen environment
Discrimination of Methionine Sulfoxide and Sulfone by Human Neutrophil Elastase
Human neutrophil elastase (HNE) is a uniquely destructive serine protease with the ability to unleash a wave of proteolytic activity by destroying the inhibitors of other proteases. Although this phenomenon forms an important part of the innate immune response to invading pathogens, it is responsible for the collateral host tissue damage observed in chronic conditions such as chronic obstructive pulmonary disease (COPD), and in more acute disorders such as the lung injuries associated with COVID-19 infection. Previously, a combinatorially selected activity-based probe revealed an unexpected substrate preference for oxidised methionine, which suggests a link to oxida-tive pathogen clearance by neutrophils. Here we use oxidised model substrates and inhibitors to confirm this observation and to show that neutrophil elastase is specifically selective for the di-oxygenated methionine sulfone rather than the mono-oxygenated methionine sulfoxide. We also posit a critical role for ordered solvent in the mechanism of HNE discrimination between the two oxidised forms methionine residue. Preference for the sulfone form of oxidised methionine is especially significant. While both host and pathogens have the ability to reduce methionine sulfoxide back to methionine, a biological pathway to reduce methionine sulfone is not known. Taken to-gether, these data suggest that the oxidative activity of neutrophils may create rapidly cleaved elas-tase “super substrates” that directly damage tissue, while initiating a cycle of neutrophil oxidation that increases elastase tissue damage and further neutrophil recruitment
Development of the RIOT Web Service and Information Technologies to enable mechanism reduction for HCCI simulations.
Abstract. New approaches are being explored to facilitate multidisciplinary collaborative research of Homogenous Charge Compression Ignition (HCCI) combustion processes. In this paper, collaborative sharing of the Range Identification and Optimization Toolkit (RIOT) and related data and models is discussed. RIOT is a developmental approach to reduce the computational of detailed chemical kinetic mechanisms, enabling their use in modeling kinetically controlled combustion applications such as HCCI. These approaches are being developed and piloted as a part of the Collaboratory for Multiscale Chemical Sciences (CMCS) project. The capabilities of the RIOT code are shared through a portlet in the CMCS portal that allows easy specification and processing of RIOT inputs, remote execution of RIOT, tracking of data pedigree, and translation of RIOT outputs to a table view and to a commonly-used mechanism format. Introduction The urgent need for high-efficiency, low-emission energy utilization technologies for transportation, power generation, and manufacturing processes presents difficult challenges to the combustion research community. The needed predictive understanding requires systematic knowledge across the full range of physical scales involved in combustion processes -from the properties and interactions of individual molecules to the dynamics and products of turbulent multi-phase reacting flows. Innovative experimental techniques and computational approaches are revolutionizing the rate at which chemical science research can produce the new information necessary to advance our combustion knowledge. But the increased volume and complexity of this information often makes it even more difficult to derive the systems-level knowledge we need. Combustion researchers have responded by forming interdisciplinary communities intent on sharing information and coordinating research priorities. Such efforts face many barriers, however, including lack of data accessibility and interoperability, missing metadata and pedigree information, efficient approaches for sharing data and analysis tools, and the challenges of working together across geography, disciplines, and a very diverse spectrum of applications and funding. This challenge is especially difficult for those developing, sharing and/or using detailed chemical models of combustion to treat the oxidation of practical fuels. This is a very complex problem, and the development of new chemistry models requires a series of steps that involve acquiring and keeping track of a large amount of data and its pedigree. Also, this data is developed using a diverse range of codes and experiments spanning ab initio chemistry codes, laboratory kinetics and flame experiments, all the way to reacting flow simulations on massively parallel computers. Each of these processes typically requires different data formats, and often the data and/or analysis codes are only accessible by personally contacting the creator. Chemical models are usually shared in a legacy file format, such as Chemki
The Jet and Circumnuclear Environment of 3C 293
We present the new HST near-infrared polarimetry, broad and narrow-band
imaging, and MERLIN 4.5GHz Multi-Frequency Synthesis radio imaging of 3C 293, a
unique radio galaxy whose host is an obvious merger remnant, in an
exceptionally under-dense region of space. We have discovered near-infrared,
optical, and ultra-violet synchrotron emission from the jet. In the optical,
the jet is mostly obscured by a dust lane, but three knots are clear in our HST
NICMOS images at 1.6 and 2.0 microns, clearly aligning with features in the
radio. The outer jet knot is highly polarized (~15%) at 2 microns, confirming
the synchrotron emission mechanism. The radio-IR spectral index steepens
significantly with distance from the nucleus, as in 3C 273 and in contrast to M
87. The inner knot is visible (with hindsight) on the WFPC2 and STIS images
obtained for the earlier 3CR HST snapshot surveys. There is no [Fe II] emission
seen associated with the jet, constraining the role of shock-induced ionisation
by the jet. Overall there is a strong implication that the NIR jet emission is
indeed synchrotron.
From our NIR images, the core of the galaxy is clearly identifiable with the
main feature in the western extension of the radio ``jet'' image, although no
unresolved AGN component is identifiable even at K-band, consistent with an
FRII-like nucleus obscured by an optically thick torus. The galaxy appears to
have a single nucleus, with any multiple nuclei falling within the central
</~100 pc.Comment: ApJ accepted. 31 pages, 12 figures reproduced here at low resolution.
High resolution version available from
http://www.stsci.edu/~floyd/BIBLIOTECA/3c293
Formations of European modernity: a historical and political sociology of Europe
This book seeks to provide an interpretation of the idea of Europe through an analysis of the course of European history. It aims to discover the structure of qualitative shifts in the relation between state, society and individual, how they occurred and what were their consequences for the formation of social and culture structures for European history. The book makes a major contribution to the debate on the idea of Europe and offers an interdisciplinary approach drawing especially from history, sociology and political theory, but also from geography and anthropology. The theoretical objective of is to make sense of the course of European history through an account of the formation of a European cultural model that emerges out of the legacies of the inter-civilizational background. It considers how in relation to this cultural model a societal structure takes shape. The tension between both gives form to Europe’s path to modernity and defines the specificity of its heritage. The structuring process that has shaped Europe made possible a model of modernity that has placed a strong emphasis on the values of social justice and solidarity. These values have been reflectively appropriated in different periods to produce different interpretations, societal outcomes and a multiplicity of projects of modernity
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