141 research outputs found
Clustering of Local Group distances: publication bias or correlated measurements? I. The Large Magellanic Cloud
The distance to the Large Magellanic Cloud (LMC) represents a key local rung
of the extragalactic distance ladder. Yet, the galaxy's distance modulus has
long been an issue of contention, in particular in view of claims that most
newly determined distance moduli cluster tightly - and with a small spread -
around the "canonical" distance modulus, (m-M)_0 = 18.50 mag. We compiled 233
separate LMC distance determinations published between 1990 and 2013. Our
analysis of the individual distance moduli, as well as of their two-year means
and standard deviations resulting from this largest data set of LMC distance
moduli available to date, focuses specifically on Cepheid and RR Lyrae
variable-star tracer populations, as well as on distance estimates based on
features in the observational Hertzsprung-Russell diagram. We conclude that
strong publication bias is unlikely to have been the main driver of the
majority of published LMC distance moduli. However, for a given distance
tracer, the body of publications leading to the tightly clustered distances is
based on highly non-independent tracer samples and analysis methods, hence
leading to significant correlations among the LMC distances reported in
subsequent articles. Based on a careful, weighted combination, in a statistical
sense, of the main stellar population tracers, we recommend that a slightly
adjusted canonical distance modulus of (m-M)_0 = 18.49 +- 0.09 mag be used for
all practical purposes that require a general distance scale without the need
for accuracies of better than a few percent.Comment: 35 pages (AASTeX preprint format), 5 postscript figures; AJ, in
press. For full database of LMC distance moduli, see
http://astro-expat.info/Data/pubbias.htm
Gravitational conundrum? Dynamical mass segregation versus disruption of binary stars in dense stellar systems
Upon their formation, dynamically cool (collapsing) star clusters will,
within only a few million years, achieve stellar mass segregation for stars
down to a few solar masses, simply because of gravitational two-body
encounters. Since binary systems are, on average, more massive than single
stars, one would expect them to also rapidly mass segregate dynamically.
Contrary to these expectations and based on high-resolution Hubble Space
Telescope observations, we show that the compact, 15-30 Myr-old Large
Magellanic Cloud cluster NGC 1818 exhibits tantalizing hints at the >= 2 sigma
level of significance (> 3 sigma if we assume a power-law secondary-to-primary
mass-ratio distribution) of an increasing fraction of F-star binary systems
(with combined masses of 1.3-1.6 Msun) with increasing distance from the
cluster center, specifically between the inner 10 to 20" (approximately
equivalent to the cluster's core and half-mass radii) and the outer 60 to 80".
If confirmed, this will offer support of the theoretically predicted but thus
far unobserved dynamical disruption processes of the significant population of
'soft' binary systems---with relatively low binding energies compared to the
kinetic energy of their stellar members---in star clusters, which we have
access to here by virtue of the cluster's unique combination of youth and high
stellar density.Comment: Accepted for publication in The Astrophysical Journal; 19 pages in
AASTeX format; 3 figure
Topical anti-inflammatory activity of Polygonum cuspidatum extract in the TPA model of mouse ear inflammation
<p>Abstract</p> <p>Background</p> <p>This study tested the ability of a characterized extract of <it>Polygonum cuspidatum </it>(PCE) to inhibit mouse ear inflammation in response to topical application of 12-<it>O-</it>tetradecanoylphorbol-13-acetate (TPA).</p> <p>Methods</p> <p>A 50% (wt:vol) ethanolic solution of commercial 200:1 PCE was applied to both ears of female Swiss mice (n = 8) at 0.075, 0.15, 0.3, 1.25 and 2.5 mg/ear 30 min after TPA administration (2 μg/ear). For comparison, 3 other groups were treated with TPA and either 1) the vehicle (50% ethanol) alone, 2) indomethacin (0.5 mg/ear), or 3) <it>trans</it>-resveratrol (0.62 mg/ear). Ear thickness was measured before TPA and at 4 and 24 h post-TPA administration to assess ear edema. Ear punch biopsies were collected at 24 h and weighed as a second index of edema. Myeloperoxidase activity was measured in each ear punch biopsy to assess neutrophil infiltration.</p> <p>Results</p> <p>PCE treatment at all doses significantly reduced ear edema compared to the TPA control. The PCE response was dose-dependent and 2.5 mg PCE significantly inhibited all markers of inflammation to a greater extent than indomethacin (0.5 mg). MPO activity was inhibited at PCE doses ≥ 1.25 mg/ear. <it>Trans-</it>resveratrol inhibited inflammation at comparable doses.</p> <p>Conclusion</p> <p>PCE inhibits development of edema and neutrophil infiltration in the TPA-treated mouse ear model of topical inflammation.</p
{2,6-Bis[(2,6-diphenylphosphanyl)oxy]-4-fluorophenyl-κ3 P,C 1,P′}(6-methyl-2,2,4-trioxo-3,4-dihydro-1,2,3-oxathiazin-3-ido-κN)palladium(II)
The title acesulfamate complex, [Pd(C30H22FO2P2)(C4H4NO4S)], contains a four-coordinate Pd(II) ion with the expected, although relatively distorted, square-planar geometry where the four L—Pd—L angles range from 79.58 (8) to 102.47 (7)°. The acesulfamate ligand is N-bound to Pd [Pd—N = 2.127 (2) Å] with a dihedral angle of 76.35 (6)° relative to the square plane. Relatively long phenyl–acesulfamate C—H⋯O and phenyl–fluorine C—H⋯F interactions consolidate the crystal packing
T1DBase: integration and presentation of complex data for type 1 diabetes research
T1DBase () [Smink et al. (2005) Nucleic Acids Res., 33, D544–D549; Burren et al. (2004) Hum. Genomics, 1, 98–109] is a public website and database that supports the type 1 diabetes (T1D) research community. T1DBase provides a consolidated T1D-oriented view of the complex data world that now confronts medical researchers and enables scientists to navigate from information they know to information that is new to them. Overview pages for genes and markers summarize information for these elements. The Gene Dossier summarizes information for a list of genes. GBrowse [Stein et al. (2002) Genome Res., 10, 1599–1610] displays genes and other features in their genomic context, and Cytoscape [Shannon et al. (2003) Genome Res., 13, 2498–2504] shows genes in the context of interacting proteins and genes. The Beta Cell Gene Atlas shows gene expression in β cells, islets, and related cell types and lines, and the Tissue Expression Viewer shows expression across other tissues. The Microarray Viewer shows expression from more than 20 array experiments. The Beta Cell Gene Expression Bank contains manually curated gene and pathway annotations for genes expressed in β cells. T1DMart is a query tool for markers and genotypes. PosterPages are ‘home pages’ about specific topics or datasets. The key challenge, now and in the future, is to provide powerful informatics capabilities to T1D scientists in a form they can use to enhance their research
T1DBase: integration and presentation of complex data for type 1 diabetes research (vol 35, pg D742, 2007)
The genomes of two key bumblebee species with primitive eusocial organization
Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation
A Common Anterior Insula Representation of Disgust Observation, Experience and Imagination Shows Divergent Functional Connectivity Pathways
Similar brain regions are involved when we imagine, observe and execute an action. Is the same true for emotions? Here, the same subjects were scanned while they (a) experience, (b) view someone else experiencing and (c) imagine experiencing gustatory emotions (through script-driven imagery). Capitalizing on the fact that disgust is repeatedly inducible within the scanner environment, we scanned the same participants while they (a) view actors taste the content of a cup and look disgusted (b) tasted unpleasant bitter liquids to induce disgust, and (c) read and imagine scenarios involving disgust and their neutral counterparts. To reduce habituation, we inter-mixed trials of positive emotions in all three scanning experiments. We found voxels in the anterior Insula and adjacent frontal operculum to be involved in all three modalities of disgust, suggesting that simulation in the context of social perception and mental imagery of disgust share a common neural substrates. Using effective connectivity, this shared region however was found to be embedded in distinct functional circuits during the three modalities, suggesting why observing, imagining and experiencing an emotion feels so different
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