124 research outputs found
Analytical approximations of K-corrections in optical and near-infrared bands
To compare photometric properties of galaxies at different redshifts, the
fluxes need to be corrected for the changes of effective rest-frame wavelengths
of filter bandpasses, called K-corrections. Usual approaches to compute them
are based on the template fitting of observed spectral energy distributions
(SED) and, thus, require multi-colour photometry. Here, we demonstrate that, in
cases of widely used optical and near-infrared filters, K-corrections can be
precisely approximated as two-dimensional low-order polynomials of only two
parameters: redshift and one observed colour. With this minimalist approach, we
present the polynomial fitting functions for K-corrections in SDSS ugriz, UKIRT
WFCAM YJHK, Johnson-Cousins UBVR_cI_c, and 2MASS JHK_s bands for galaxies at
redshifts Z<0.5 based on empirically-computed values obtained by fitting
combined optical-NIR SEDs of a set of 10^5 galaxies constructed from SDSS DR7
and UKIDSS DR5 photometry using the Virtual Observatory. For luminous red
galaxies we provide K-corrections as functions of their redshifts only. In two
filters, g and r, we validate our solutions by computing K-corrections directly
from SDSS DR7 spectra. We also present a K-corrections calculator, a web-based
service for computing K-corrections on-line.Comment: 13 pages, 7 figures, 25 tables. Accepted for publication in MNRAS.
This version contains low-resolution figures. The "K-corrections calculator"
service is available at http://kcor.sai.msu.ru
Climate Change and Human Health Impacts in the United States: An Update on the Results of the U.S. National Assessment
The health sector component of the first U.S. National Assessment, published in 2000, synthesized the anticipated health impacts of climate variability and change for five categories of health outcomes: impacts attributable to temperature, extreme weather events (e.g., storms and floods), air pollution, water- and food-borne diseases, and vector- and rodent-borne diseases. The Health Sector Assessment (HSA) concluded that climate variability and change are likely to increase morbidity and mortality risks for several climate-sensitive health outcomes, with the net impact uncertain. The objective of this study was to update the first HSA based on recent publications that address the potential impacts of climate variability and change in the United States for the five health outcome categories. The literature published since the first HSA supports the initial conclusions, with new data refining quantitative exposure–response relationships for several health end points, particularly for extreme heat events and air pollution. The United States continues to have a very high capacity to plan for and respond to climate change, although relatively little progress has been noted in the literature on implementing adaptive strategies and measures. Large knowledge gaps remain, resulting in a substantial need for additional research to improve our understanding of how weather and climate, both directly and indirectly, can influence human health. Filling these knowledge gaps will help better define the potential health impacts of climate change and identify specific public health adaptations to increase resilience
Caught in the Act: Strong, Active Ram Pressure Stripping in Virgo Cluster Spiral NGC 4330
We present a multi-wavelength study of NGC 4330, a highly-inclined spiral
galaxy in the Virgo Cluster which is a clear example of strong, ongoing ICM-ISM
ram pressure stripping. The HI has been removed from well within the
undisturbed old stellar disk, to 50% - 65% of R_25. Multi-wavelength data (WIYN
BVR and H-alpha, VLA 21-cm HI and radio continuum, and GALEX NUV and FUV)
reveal several one-sided extraplanar features likely caused by ram pressure at
an intermediate disk-wind angle. At the leading edge of the interaction, the
H-alpha and dust extinction curve sharply out of the disk in a remarkable and
distinctive "upturn" feature that may be generally useful as a diagnostic
indicator of active ram pressure. On the trailing side, the ISM is stretched
out in a long tail which contains 10% of the galaxy's total HI emission, 6 - 9%
of its NUV-FUV emission, but only 2% of the H-alpha. The centroid of the HI
tail is downwind of the UV/H-alpha tail, suggesting that the ICM wind has
shifted most of the ISM downwind over the course of the past 10 - 300 Myr.
Along the major axis, the disk is highly asymmetric in the UV, but more
symmetric in H-alpha and HI, also implying recent changes in the distributions
of gas and star formation. The UV-optical colors indicate very different star
formation histories for the leading and trailing sides of the galaxy. On the
leading side, a strong gradient in the UV-optical colors of the gas-stripped
disk suggests that it has taken 200-400 Myr to strip the gas from a radius of
>8 to 5 kpc, but on the trailing side there is no age gradient. All our data
suggest a scenario in which NGC 4330 is falling into cluster center for first
time and has experienced a significant increase in ram pressure over the last
200-400 Myr.Comment: AJ accepted; 22 pages, 25 figures, version with full-resolution
figures available at http://www.astro.yale.edu/abramso
Galaxy and Mass Assembly (GAMA): Variation in Galaxy Structure Across the Green Valley
Using a sample of 472 local Universe (z < 0.06) galaxies in the stellar mass range
10.25 < log M*/MG < 10.75, we explore the variation in galaxy structure as a function of morphology and galaxy colour. Our sample of galaxies is sub-divided into red, green and blue colour groups and into elliptical and non-elliptical (disk-type) morphologies.
Using KiDS and VIKING derived postage stamp images, a group of eight volunteers visually classified bars, rings, morphological lenses, tidal streams, shells and signs of merger activity for all systems. We find a significant surplus of rings (2.3σ) and lenses (2.9σ) in disk-type galaxies as they transition across the green valley. Combined, this implies a joint ring/lens green valley surplus significance of 3.3σ relative to equivalent disk-types within either the blue cloud or the red sequence. We recover a bar fraction of ∼ 44% which remains flat with colour, however, we find that the presence of a bar acts to modulate the incidence of rings and (to a lesser extent) lenses, with rings in barred disk-type galaxies more common by ∼ 20 − 30 percentage points relative to their unbarred counterparts, regardless of colour. Additionally, green valley disk-type galaxies with a bar exhibit a significant 3.0σ surplus of lenses relative to their blue/red analogues. The existence of such structures rules out violent transformative events as the primary end-of-life evolutionary mechanism, with a more passive scenario the favoured candidate for the majority of galaxies rapidly transitioning across the green valley.
Key words: galaxies: elliptical and lenticular, cD – galaxies: spiral – galaxies: evo- lution – galaxies: star formation – galaxies: statistics – galaxies: structur
What is damaging the kidney in lupus nephritis?
Despite marked improvements in the survival of patients with severe lupus nephritis over the past 50 years, the rate of complete clinical remission after immune suppression therapy i
TRY plant trait database – enhanced coverage and open access
Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
Evidence for SMAD3 as a modifier of breast cancer risk in BRCA2 mutation carriers
Abstract
Introduction
Current attempts to identify genetic modifiers of BRCA1 and BRCA2 associated risk have focused on a candidate gene approach, based on knowledge of gene functions, or the development of large genome-wide association studies. In this study, we evaluated 24 SNPs tagged to 14 candidate genes derived through a novel approach that analysed gene expression differences to prioritise candidate modifier genes for association studies.
Methods
We successfully genotyped 24 SNPs in a cohort of up to 4,724 BRCA1 and 2,693 BRCA2 female mutation carriers from 15 study groups and assessed whether these variants were associated with risk of breast cancer in BRCA1 and BRCA2 mutation carriers.
Results
SNPs in five of the 14 candidate genes showed evidence of association with breast cancer risk for BRCA1 or BRCA2 carriers (P < 0.05). Notably, the minor alleles of two SNPs (rs7166081 and rs3825977) in high linkage disequilibrium (r
2 = 0.77), located at the SMAD3 locus (15q22), were each associated with increased breast cancer risk for BRCA2 mutation carriers (relative risk = 1.25, 95% confidence interval = 1.07 to 1.45, P
trend = 0.004; and relative risk = 1.20, 95% confidence interval = 1.03 to 1.40, P
trend = 0.018).
Conclusions
This study provides evidence that the SMAD3 gene, which encodes a key regulatory protein in the transforming growth factor beta signalling pathway and is known to interact directly with BRCA2, may contribute to increased risk of breast cancer in BRCA2 mutation carriers. This finding suggests that genes with expression associated with BRCA1 and BRCA2 mutation status are enriched for the presence of common genetic modifiers of breast cancer risk in these populations
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