9 research outputs found
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Regulation of 5-HT Receptors and the Hypothalamic-Pituitary-Adrenal Axis
Disturbances in the serotonin (5-HT) system is the neurobiological abnormality most consistently associated with suicide. Hyperactivity of the hypothalmic-pituitary-adrenal (HPA) axis is also described in suicide victims. The HPA axis is the classical neuroendocrine system that responds to stress and whose final product, corticosteroids, targets components of the limbic system, particularly the hippocampus. We will review resulsts from animal studies that point to the possibility that many of the 5-HT receptor changes observed in suicide brains may be a result of, or may be worsened by, the HPA overactivity that may be present in some suicide victims. The results of these studies can be summarized as follows: (1) chronic unpredictable stress produces high corticosteroid levels in rats; (2) chronic stress also results in changes in specific 5-HT receptors (increases in cortical 5-HT2A and decreases in hipocampal 5-HT1A and 5-HT1B); (3) chronic antidepressant administration prevents many of the 5-HT receptor changes observed after stress; and (4) chronic antidepressant administration reverses the overactivity of the HPA axis. If indeed 5-HT receptors have a partial role in controlling affective states, then their modulation by corticosteroids provides a potential mechanism by which these hormones may regulate mood. These data may also provide a biological understanding of how stressful events may increase the risk for suicide in vulnerable individuals and may help us elucidate the neurobiological underpinnings of treatment resistance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73437/1/j.1749-6632.1997.tb52357.x.pd
Fijimycins A-C, three antibacterial etamycin-class depsipetides from a marine-derived Streptomyces sp
Three new depsipeptides, fijimycins A–C (1–3), together with the known etamycin A (4), were isolated and identified from the fermentation broth of strain CNS-575, a Streptomyces sp. cultured from a marine sediment sample collected off Nasese, Fiji. The planar structures of the new fijimycins were assigned by combined interpretation of NMR and MS/MS spectroscopic data. These assignments were complicated by the fact that 1–3 occurred as complex amide conformational mixtures. The absolute configurations of the component amino acids were established using the Marfey’s method. Fijimycins A–C, and etamycin A, were shown to possess significant in vitro antibacterial activity against three methicillin-resistant Staphylococcus aureus (MRSA) strains with MIC100 values between 4 and 16 μg mL−1
Using citizen science to investigate the role of productivity in House Sparrow Passer domesticus population trends
Capsule Seasonal variation in garden House Sparrow numbers provides a tool to examine overall annual productivity, measuring the combined success of multiple breeding attempts and post-fledging survival.Aims To develop a metric to use British Trust for Ornithology (BTO) Garden BirdWatch (GBW) data to measure annual productivity in House Sparrows across regions and habitats exhibiting contrasting population trends.Methods We examine variation in annual productivity by quantifying the height of the seasonal peak of garden House Sparrows relative to pre-breeding numbers. We use BTO Nest Record Scheme (NRS) data to explore the demographic drivers of variation in this metric and relate differences to BTO/Joint Nature Conservation Committee/Royal Society for Protection of Birds Breeding Bird Survey regional population trends.Results GBW annual productivity was similar between rural and urban gardens but was lower in the south and the east of Britain (1.32 fledglings per adult), where populations are declining, than in the north and west where populations are stable (1.37 fledglings per adult). Analysis of NRS data showed similar regional variation in clutch and broods sizes.Conclusion The intensity of effort required to measure breeding success directly through nest monitoring has limited the scale of data collection but these results suggest that Garden BirdWatch (GBW) data can provide a measure of annual productivity across multiple sites. Regional variation in annual productivity (primarily driven by reduced clutch sizes) mirrors population trends, suggesting that reduced breeding success may be influencing House Sparrow population recovery