1,896 research outputs found
Clinical surveillance of thrombotic microangiopathies in Scotland, 2003-2005
The prevalence, incidence and outcomes of haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP) are not well established in adults or children from prospective studies. We sought to identify both outcomes and current management strategies using prospective, national surveillance of HUS and TTP, from 2003 to 2005 inclusive. We also investigated the links between these disorders and factors implicated in the aetiology of HUS and TTP including infections, chemotherapy, and immunosuppression. Most cases of HUS were caused by verocytotoxin-producing Escherichia coli (VTEC), of which serotype O157 predominated, although other serotypes were identified. The list of predisposing factors for TTP was more varied although use of immunosuppressive agents and severe sepsis, were the most frequent precipitants. The study demonstrates that while differentiating between HUS and TTP is sometimes difficult, in most cases the two syndromes have quite different predisposing factors and clinical parameters, enabling clinical and epidemiological profiling for these disorders
Mouse embryos in culture: models for understanding diabetes-induced embryopathies and gene function.
Both the metabolic studies on diabetes and the genetic studies using antisense oligodeoxynucleotides clearly demonstrate the importance and usefulness of rodent whole embryo culture. Without this technique, these studies would be impossible and, consequently, our knowledge of both normal and abnormal development would not be as advanced as it is today. The culture system fills a unique niche in studies in the fields of developmental biology and teratology and these sciences would have been less well served without Dr. New's contribution
Radiolabelling of Corynebacterium parvum and its distribution in mice.
Corynebacterium parvum was labelled by growing live bacteria in the presence of [3H]thymidine. The bacteria were killed by formalin, washed thoroughly and resuspended at a concentration of 7 mg dry weight/ml. An activity of 1-6 X 10(5) ct/min/0-1 ml was obtained. The biological properties (inhibition of tumour growth and hepatosplenomegaly) of the labelled C. parvum were compared with those of commercially available vaccine, and were found to be similar. Labelled C. parvum was injected i.v., i.p., or s.c. into normal C57BL mice and the localization of activity determined at 4 h and 1,3,7 and 14 days after injection. After i.v. or i.p. injection, highest counts were recorded in the liver. Moderate activity was found in the spleen, lungs and small gut. After s.c. injection, the majority of radioactive label was detected at the site of injection and little found in other tissues. The distribution of injected C. parvum was also studied in mice bearing Lewis tumour, and was found to be similar to that in normal mice. Moderate amounts of labelled C. parvum were recovered from tumour. There appeared to be no relationship between the antitumour effect of C. parvum given by a particular route of injection and the concentration of C. parvum recovered from the tumour
Further Observational Evidence for a Critical Ionising Luminosity in Active Galaxies
We report the results of a survey for HI 21-cm absorption at redshifts of z >
2.6 in a new sample of radio sources with the Green Bank and Giant Metrewave
Radio Telescopes. From a total of 25 targets, we report zero detections in the
16 for which optical depth limits could be obtained. Based upon the detection
rate for z > 0.1 associated absorption, we would expect approximately four
detections. Of the 11 which have previously not been searched, there is
sufficient source-frame optical/ultra-violet photometry to determine the
ionising photon rate for four. Adding these to the literature, the hypothesis
that there is a critical rate of logQ = 56 ionising photons per second is now
significant at ~7 sigma. This reaffirms our assertion that searching z > 3
active galaxies for which optical redshifts are available selects sources in
which the ultra-violet luminosity is sufficient to ionise all of the neutral
gas in the host galaxy.Comment: Accepted by MNRA
Raciocínio moral na tomada de decisões em relação a questões sociocientíficas: o exemplo do melhoramento genético humano
The Sub-parsec Scale Radio Properties of Southern Starburst Galaxies. I. Supernova Remnants, the Supernova Rate, and the Ionised Medium in the NGC 253 Starburst
Wide-field, very long baseline interferometry (VLBI) observations of the
nearby starburst galaxy NGC 253, obtained with the Australian Long Baseline
Array (LBA), have produced a 2.3 GHz image with a maximum angular resolution of
15 mas (0.3 pc). Six sources were detected, all corresponding to sources
identified in higher frequency (>5 GHz) VLA images. One of the sources,
supernova remnant 5.48-43.3, is resolved into a shell-like structure
approximately 90 mas (1.7 pc) in diameter. From these data and data from the
literature, the spectra of 20 compact radio sources in NGC 253 were modelled
and found to be consistent with free-free absorbed power laws. Broadly, the
free-free opacity is highest toward the nucleus but varies significantly
throughout the nuclear region (tau_0 ~ 1->20), implying that the overall
structure of the ionised medium is clumpy. Of the 20 sources, nine have flat
intrinsic spectra associated with thermal radio emission and the remaining 11
have steep intrinsic spectra, associated with synchrotron emission from
supernova remnants. A supernova rate upper limit of 2.4 yr^-1 is determined for
the inner 320 pc region of the galaxy at the 95% confidence level, based on the
lack of detection of new sources in observations spanning almost 17 years and a
simple model for the evolution of supernova remnants. A supernova rate of >0.14
(v/10^4) yr^-1 is implied from estimates of supernova remnant source counts,
sizes and expansion rates, where v is the radial expansion velocity of the
supernova remnant in km s^-1. A star formation rate of 3.4 (v/10^4) <
SFR(M<=5Msun) < 59 Msun yr^-1 has been estimated directly from the supernova
rate limits and is of the same order of magnitude as rates determined from
integrated FIR and radio luminosities.Comment: Accepted by the Astronomical Journal. 34 pages, 6 figures; fixed
typos in assumed expansion velocit
Radio Sources in Low-Luminosity Active Galactic Nuclei. I. VLA Detections of Compact, Flat-Spectrum Cores
We report a 0.2" resolution, 15 GHz survey of a sample of 48 low-luminosity
active galactic nuclei with the Very Large Array. Compact radio emission has
been detected in 57% (17 of 30) of LINERs and low-luminosity Seyferts, at least
15 of which have a flat to inverted radio spectrum (alpha > -0.3). The compact
radio cores are found in both type 1 (i.e. with broad Halpha) and type 2
(without broad Halpha) nuclei. The 2 cm radio power is significantly correlated
with the emission-line ([OI] lambda6300) luminosity. While the present
observations are consistent with the radio emission originating in star-forming
regions, higher resolution radio observations of 10 of the detected sources,
reported in a companion paper (Falcke et al. 2000), show that the cores are
very compact (= 10^8K) and
probably synchrotron self-absorbed, ruling out a starburst origin. Thus, our
results suggest that at least 50% of low-luminosity Seyferts and LINERs in the
sample are accretion powered, with the radio emission presumably coming from
jets or advection-dominated accretion flows. We have detected only 1 of 18
`transition' (i.e. LINER + HII) nuclei observed, indicating their radio cores
are significantly weaker than those of `pure' LINERs.Comment: To appear in the Astrophysical Journal, October 20, 200
SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. II. The Source Catalogue
This paper is the second in a series describing the Sydney University
Molonglo Sky Survey (SUMSS) being carried out at 843MHz with the Molonglo
Observatory Synthesis Telescope (MOST). The survey will consist of ~590 4.3deg.
x 4.3deg. mosaic images with 45"x45"cosec|dec.| resolution, and a source
catalogue. In this paper we describe the initial release (version 1.0) of the
source catalogue consisting of 107,765 radio sources made by fitting elliptical
gaussians in 271 SUMSS mosaics to a limiting peak brightness of 6mJy/beam at
dec.-50deg.. The catalogue covers
approximately 3500deg^2 of the southern sky with dec.<=-30deg., about 43 per
cent of the total survey area. Positions in the catalogue are accurate to
within 1"-2" for sources with peak brightness A>=20mJy/beam and are always
better than 10". The internal flux density scale is accurate to within 3 per
cent. Image artefacts have been classified using a decision tree, which
correctly identifies and rejects spurious sources in over 96 per cent of cases.
Analysis of the catalogue shows that it is highly uniform and is complete to
8mJy at dec.-50deg.. In this release of the
catalogue about 7000 sources are found in the overlap region with the NRAO VLA
Sky Survey (NVSS) at 1.4GHz. We calculate a median spectral index of
alpha=-0.83 between 1.4GHz and 843MHz. This version of the catalogue will be
released via the World Wide Web with future updates as new mosaics are
released.Comment: 15 pages, 15 figures, accepted by MNRAS, Catalogue at
http://www.astrop.physics.usyd.edu.au/sumssca
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