717 research outputs found
Starburst Galaxies
Star-formation and the Starburst phenomenon are presented with respect to a
number of nearby star-forming galaxies where our understanding of the process
can be calibrated. Methods of estimating star-formation rates are discussed
together with the role played in the investigation of the process by
multi-wavelength studies of a few selected starburst galaxies (especially the
well studied galaxy M82). Our understanding of nearby systems allows us to
study the star-formation history of the Universe by observing high-redshift
starburst galaxies. These begin to dominate the radio source populations at
centimetric wavelengths at flux densities below a few 10s of Jy. New very
sensitive, high resolution telescopes in the sub-mm and radio will
revolutionize our understanding of these distant star-forming systems, some of
which may contain embedded AGN.Comment: 15 pages, 19 figures, To appear in the proceedings of `The 8th
European VLBI Network Symposium on New Developments in VLBI Science and
Technology', ed. A. Marecki et al., held in Torun, Poland, on September
26-29, 2006 (Invited Review
High-z radio starbursts host obscured X-ray AGN
We use Virtual Observatory methods to investigate the association between
radio and X-ray emission at high redshifts. Fifty-five of the 92 HDF(N) sources
resolved by combining
MERLIN+VLA data were detected by Chandra, of which 18 are hard enough and
bright enough to be obscured AGN. The high-z population of microJy radio
sources is dominated by starbursts an order of magnitude more active and more
extended than any found at z<1 and at least a quarter of these simultaneously
host highly X-ray-luminous obscured AGN.Comment: 4 pages, 2 figures, To appear in the proceedings of 'At the Edge of
the Universe' (9-13 October 2006, Sintra, Portugal
An evolution of the IR-Radio correlation?
Using extremely deep (rms 3.3 microJy/bm) 1.4GHz sub-arcsecond resolution
MERLIN + VLA radio observations of a 8'.5 by 8'.5 field centred upon the Hubble
Deep Field North, in conjunction with Spitzer 24 micron data we present an
investigation of the radio-MIR correlation at very low flux densities. By
stacking individual sources within these data we are able to extend the
MIR-radio correlation to the extremely faint (~microJy and even sub-microJy)
radio source population. Tentatively we demonstrate a small deviation from the
correlation for the faintest MIR sources. We suggest that this small observed
change in the gradient of the correlation is the result of a suppression of the
MIR emission in faint star-forming galaxies. This deviation potentially has
significant implications for using either the MIR or non-thermal radio emission
as a star-formation tracer at low luminosities.Comment: To Appear in The Modern Radio Universe: From Planets to Dark Energy
Conference (Oct 1-5 2007, The University of Manchester) Editors: Beswick,
Diamond & Schilizz
Book reviews
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45702/1/11336_2005_Article_BF02289852.pd
Oral Bromelain Attenuates Inflammation in an Ovalbumin-induced Murine Model of Asthma
Bromelain, a widely used pineapple extract with cysteine protease activity, has been shown to have immunomodulatory effects in a variety of immune system models. The purpose of the present study was to determine the effects of orally administered bromelain in an ovalbumin (OVA)-induced murine model of acute allergic airway disease (AAD). To establish AAD, female C57BL/6J mice were sensitized with intraperitoneal (i.p.) OVA/alum and then challenged with OVA aerosols for 3 days. Mice were gavaged with either (phosphate buffered saline)PBS or 200 mg/kg bromelain in PBS, twice daily for four consecutive days, beginning 1 day prior to OVA aerosol challenge. Airway reactivity and methacholine sensitivity, bronchoalveolar lavage (BAL) cellular differential, Th2 cytokines IL-5 and IL-13, and lung histology were compared between treatment groups. Oral bromelain-treatment of AAD mice demonstrated therapeutic efficacy as evidenced by decreased methacholine sensitivity (P ≤ 0.01), reduction in BAL eosinophils (P ≤ 0.02) and IL-13 concentrations (P ≤ 0.04) as compared with PBS controls. In addition, oral bromelain significantly reduced BAL CD19+ B cells (P ≤ 0.0001) and CD8+ T cells (P ≤ 0.0001) in AAD mice when compared with controls. These results suggest that oral treatment with bromelain had a beneficial therapeutic effect in this murine model of asthma and bromelain may also be effective in human conditions
Phylogenetic signals and predictability in plant-soil feedbacks
There is strong evidence for a phylogenetic signal in the degree to which species share co-evolved biotic partners and in the outcomes of biotic interactions. This implies there should be a phylogenetic signal in the outcome of feedbacks between plants and soil microbiota they cultivate. However, attempts to identify a phylogenetic signal in plant-soil feedbacks have produced mixed results. We clarify how phylogenetic signals could arise in plant-soil feedbacks and use a recent compilation of data from feedback experiments to identify: 1) whether there is a phylogenetic signal in the outcome of plant-soil feedbacks; and 2) whether any signal arises through directional or divergent changes in feedback outcomes with evolutionary time. We find strong evidence for a divergent phylogenetic signal in feedback outcomes. Distantly related plant species show more divergent responses to each other's soil microbiota than closely related plant species. The pattern of divergence implies occasional co-evolutionary shifts in how plants interact with soil microbiota, with strongly contrasting feedback responses among some plant lineages. Our results highlight that it is difficult to predict feedback outcomes from phylogeny alone, other than to say that more closely related species tend to have more similar responses
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