167 research outputs found
VLA Polarimetry of Two Extended Radio Galaxies
Multi-wavelength VLA observations of two extended radio galaxies, 0235-197
and 1203+043 are presented. There is some evidence from earlier studies that
these two sources exhibit low frequency (<1 GHz) variability. This work shows
that both sources have linear polarizations, if any, below the detection limits
at 320 MHz, so we cannot explain the variability as being due to instrumental
polarization effects as has been suggested for 3C159. Refractive scintillation
may be the cause of the variability in 0235-197. This would require the
existence of a bright, compact component in one of the hot spots seen in these
observations. This is not implausible but the resolution of this observational
program is insufficent to address that question. The radio source 1203+043
lacks any bright compact component thereby ruling out a refractive
scintillation mechanism for its variability. Consequently, it is possible that
claims of variability in this source are spurious. However, the 320 MHz VLA
observations show that 1203+043 has an `X'-shaped radio structure. This is a
rare morphology for the brightness distribution of a radio galaxy; the
implications of this are examined.Comment: 8 pages, plain tex, accepted by Astronomy and Astrophysics,
Supplement Serie
X-ray variability in M87
We present the evidence for X-ray variability from the core and from knot A
in the M87 jet based on data from two observations with the Einstein
Observatory High Resolution Imager (HRI) and three observations with the ROSAT
HRI. The core intensity showed a 16% increase in 17 months ('79-'80); a 12%
increase in the 3 years '92 to '95; and a 17% drop in the last half of 1995.
The intensity of knot A appears to have decreased by 16% between 92Jun and
95Dec. Although the core variability is consistent with general expectations
for AGN nuclei, the changes in knot A provide constraints on the x-ray emission
process and geometry. Thus we predict that the x-ray morphology of knot A will
differ significantly from the radio and optical structure.Comment: 9 pages latex plus 6 ps figs. To appear in Monthly Notices of the RA
Radio polarimetry of compact steep spectrum sources at sub-arcsecond resolution
Aims - We report new Very Large Array polarimetric observations of Compact
Steep-Spectrum (CSS) sources at 8.4, 15, and 23GHz. Methods - Using
multi-frequency VLA observations we have derived sub-arcsecond resolution
images of the total intensity, polarisation, and rotation measure (RM)
distributions. Results heading - We present multi-frequency VLA polarisation
observations of CSS sources. About half of the sources are point-like even at
the resolution of about 0.1x0.1 arcseconds. The remaining sources have double
or triple structure. Low values for the percentage of polarised emission in CSS
sources is confirmed. On the average, quasars are more polarised than galaxies.
A wide range of RM values have been measured. There are clear indications of
very large RMs up to 5\,585 rad m**(-2). CSS galaxies are characterized by RM
values that are larger than CSS quasars. The majority of the objects show very
large values of RM. Conclusions - The available data on sub-arcsecond-scale
rest-frame RM estimates for CSS sources show that these have a wide range of
values extending up to about 36,000 rad m**(-2). RM estimates indicate an
overall density of the magneto-ionic medium larger than classical radio
sources.Comment: Accepted for publication by Astronomy & Astrophysic
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From commercialising intellectual property to facilitating open innovation: the evolution of UK biotechnology incubators
This paper investigates the changing landscape of biotechnology incubators in the UK and evidences their evolution from 1999 to 2017. We highlight the changing policy environment for biotechnology incubators and begin to investigate the evolution of UK biotechnology incubators from facilities that primarily support the commercialisation of intellectual property derived from universities to facilities that reuse former pharmaceutical research and development laboratories and collocate with operational pharmaceutical companies. This study uses two desk-based surveys that provide snap-shots of 21 biotechnology incubators taken in December 2012 and December 2017. The surveys provide a detailed examination of the characteristics of UK biotechnology incubators and their tenant companies. We observe the appearance of biotechnology incubators with an economic regeneration remit, funded by and working in partnership with regional government (BioPark Hertfordshire & BioCity Nottingham). We also observe the appearance of corporate biotechnology incubators (Akcomak, 2009) co-located on operational pharmaceutical research and development sites with an open innovation remit e.g. Astra Zeneca (Manchester), GlaxoSmithKline (Stevenage) and Boots (Nottingham). We propose that regional and national policy initiatives and changes in the business model of large pharmaceutical companies have been the main drivers for the evolution of biotechnology incubators in the UK
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