335 research outputs found
IVOA Recommendation: Data Model for Astronomical DataSet Characterisation
This document defines the high level metadata necessary to describe the
physical parameter space of observed or simulated astronomical data sets, such
as 2D-images, data cubes, X-ray event lists, IFU data, etc.. The
Characterisation data model is an abstraction which can be used to derive a
structured description of any relevant data and thus to facilitate its
discovery and scientific interpretation. The model aims at facilitating the
manipulation of heterogeneous data in any VO framework or portal. A VO
Characterisation instance can include descriptions of the data axes, the range
of coordinates covered by the data, and details of the data sampling and
resolution on each axis. These descriptions should be in terms of physical
variables, independent of instrumental signatures as far as possible.
Implementations of this model has been described in the IVOA Note available
at: http://www.ivoa.net/Documents/latest/ImplementationCharacterisation.html
Utypes derived from this version of the UML model are listed and commented in
the following IVOA Note:
http://www.ivoa.net/Documents/latest/UtypeListCharacterisationDM.html
An XML schema has been build up from the UML model and is available at:
http://www.ivoa.net/xml/Characterisation/Characterisation-v1.11.xsdComment: http://www.ivoa.ne
IVOA Recommendation: An IVOA Standard for Unified Content Descriptors Version 1.1
This document describes the current understanding of the IVOA controlled
vocabulary for describing astronomical data quantities, called Unified Content
Descriptors (UCDs).
The present document defines a new standard (named UCD1+) improving the first
generation of UCDs (hereafter UCD1). The basic idea is to adopt a new syntax
and vocabulary requiring little effort for people to adapt softwares already
using UCD1.
This document also addresses the questions of maintenance and evolution of
the UCD1+. Examples of use cases within the VO, and tools for using UCD1+ are
also described
An expanded multilocus sequence typing scheme for propionibacterium acnes : investigation of 'pathogenic', 'commensal' and antibiotic resistant strains
The Gram-positive bacterium Propionibacterium acnes is a member of the normal human skin microbiota and is associated with various infections and clinical conditions. There is tentative evidence to suggest that certain lineages may be associated with disease and others with health. We recently described a multilocus sequence typing scheme (MLST) for P. acnes based on seven housekeeping genes (http://pubmlst.org/pacnes). We now describe an expanded eight gene version based on six housekeeping genes and two ‘putative virulence’ genes (eMLST) that provides improved high resolution typing (91eSTs from 285 isolates), and generates phylogenies congruent with those based on whole genome analysis. When compared with the nine gene MLST scheme developed at the University of Bath, UK, and utilised by researchers at Aarhus University, Denmark, the eMLST method offers greater resolution. Using the scheme, we examined 208 isolates from disparate clinical sources, and 77 isolates from healthy skin. Acne was predominately associated with type IA1 clonal complexes CC1, CC3 and CC4; with eST1 and eST3 lineages being highly represented. In contrast, type IA2 strains were recovered at a rate similar to type IB and II organisms. Ophthalmic infections were predominately associated with type IA1 and IA2 strains, while type IB and II were more frequently recovered from soft tissue and retrieved medical devices. Strains with rRNA mutations conferring resistance to antibiotics used in acne treatment were dominated by eST3, with some evidence for intercontinental spread. In contrast, despite its high association with acne, only a small number of resistant CC1 eSTs were identified. A number of eSTs were only recovered from healthy skin, particularly eSTs representing CC72 (type II) and CC77 (type III). Collectively our data lends support to the view that pathogenic versus truly commensal lineages of P. acnes may exist. This is likely to have important therapeutic and diagnostic implications
The Far-infrared Continuum of Quasars
ISO provides a key new far-infrared window through which to observe the
multi-wavelength spectral energy distributions (SEDs) of quasars and active
galactic nuclei (AGN). It allows us, for the first time, to observe a
substantial fraction of the quasar population in the far-IR, and to obtain
simultaneous, multi-wavelength observations from 5--200 microns. With these
data we can study the behavior of the IR continuum in comparison with
expectations from competing thermal and non-thermal models. A key to
determining which mechanism dominates, is the measurement of the peak
wavelength of the emission and the shape of the far-IR--mm turnover. Turnovers
which are steeper than frequency^2.5 indicate thermal dust emission in the
far-IR.
Preliminary results from our ISO data show broad, fairly smooth, IR continuum
emission with far-IR turnovers generally too steep to be explained by
non-thermal synchrotron emission. Assuming thermal emission throughout leads to
a wide inferred temperature range of 50-1000 K. The hotter material, often
called the AGN component, probably originates in dust close to and heated by
the central source, e.g. the ubiquitous molecular torus. The cooler emission is
too strong to be due purely to cool, host galaxy dust, and so indicates either
the presence of a starburst in addition to the AGN or AGN-heated dust covering
a wider range of temperatures than present in the standard, optically thick
torus models.Comment: 4 pages, to be published in the proceedings of "The Universe as Seen
by ISO," ed. M. Kessler. This and related papers can be found at
http://hea-www.harvard.edu/~ehooper/ISOkp/ISOkp.htm
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