24,109 research outputs found
Microscopes and computers combined for analysis of chromosomes
Scanning machine CHLOE, developed for photographic use, is combined with a digital computer to obtain quantitative and statistically significant data on chromosome shapes, distribution, density, and pairing. CHLOE permits data acquisition about a chromosome complement to be obtained two times faster than by manual pairing
Comment on "Valence QCD: Connecting QCD to the Quark Model"
I criticize certain conclusions about the physics of hadrons drawn from a
"valence QCD" approximation to QCD.Comment: 12 pages, 8 figures; some minor improvements made to the tex
The Mid-infrared Fine-structure Lines of Neon as an Indicator of Star For mation Rate in Galaxies
The fine-structure lines of singly ([Ne II] 12.8 micron) and doubly ([Ne III]
15.6 micron) ionized neon are among the most prominent features in the
mid-infrared spectra of star-forming regions, and have the potential to be a
powerful new indicator of the star formation rate in galaxies. Using a sample
of star-forming galaxies with measurements of the fine-structure lines
available from the literature, we show that the sum of the [Ne II] and [Ne III]
luminosities obeys a tight, linear correlation with the total infrared
luminosity, over 5 orders of magnitude in luminosity. We discuss the formation
of the lines and their relation with the Lyman continuum luminosity. A simple
calibration between star formation rate and the [Ne II]+[Ne III] luminosity is
presented.Comment: To appear in ApJ. 8 page
Quantitative spectroscopy of B-type supergiants
Context. B-type supergiants are versatile tools to address various
astrophysical topics, ranging from stellar atmospheres over stellar and
galactic evolution to the cosmic distance scale. Aims. A hybrid non-LTE
approach - line-blanketed model atmospheres computed under the assumption of
local thermodynamic equilibrium (LTE) in combination with line formation
calculations that account for deviations from LTE - is tested for quantitative
analyses of B-type supergiants with masses , characterising a
sample of 14 Galactic objects. Methods. Hydrostatic plane-parallel atmospheric
structures and synthetic spectra computed with Kurucz's Atlas12 code together
with the non-LTE line-formation codes Detail/Surface are compared to results
from full non-LTE calculations with Tlusty, and the effects of turbulent
pressure on the models are investigated. High-resolution spectra are analysed
for atmospheric parameters, using Stark-broadened hydrogen lines and multiple
metal ionisation equilibria, and for elemental abundances. Fundamental stellar
parameters are derived by considering stellar evolution tracks and Gaia EDR3
parallaxes. Interstellar reddening towards the target stars is determined by
matching model spectral energy distributions to observed ones. Results. Our
hybrid non-LTE approach turns out to be equivalent to hydrostatic full non-LTE
modelling for the deeper photospheric layers of the B-type supergiants
considered. Turbulent pressure can become relevant for microturbulent
velocities larger than 10 km s. High precision and accuracy is achieved
for all derived parameters by bringing multiple indicators to agreement
simultaneously. Abundances for chemical species (He, C, N, O, Ne, Mg, Al, Si,
S, Ar, Fe) are derived with uncertainties of 0.05 to 0.10 dex. The derived
ratios N/C vs. N/O tightly follow the predictions from Geneva stellar evolution
models.Comment: 31 pages, 24 figures, Accepted for publication in Astronomy &
Astrophysics, Data: https://doi.org/10.5281/zenodo.680256
Moral reasoning in adaptation to climate change
This is the final version of the article. Available from the publisher via the DOI in this record.Moral foundations theory argues that moral reasoning is widely observed and fundamental to the legitimacy of relevant governance and policy interventions. A new analytical framework to examine and test how moral reasoning underpins and legitimizes governance and practice on adaptation to climate change risks is proposed. It develops a typology of eight categories of vulnerability-based and system-based moral reasoning that pertain to the dilemmas around adaptation and examines the prevalence of these moral categories in public discourse about specific adaptation issues. The framework is tested using data on climate change impact, adaptation, and societal responsibility, drawn from 14 focus groups comprising 148 participants across the UK. Participants consistently use moral reasoning to explain their views on climate adaptation; these include both vulnerability-based and system-based framings. These findings explain public responses to adaptation options and governance, and have implications for the direction of adaptation policy, including understanding which types of reasoning support politically legitimate interventions.We acknowledge funding from the University of Exeter Humanities and Social Science Strategy; the UK Economic and Social Research Council (Grant ES/M006867/1); and National Institute for Health Research, Health Protection Research Unit (NIHR HPRU) in Environmental Change and Health at the London School of Hygiene and Tropical Medicine in partnership with Public Health England. We thank IPSOS-MORI and the UK Department for Environment Food and Rural Affairs for access to the data used here. We benefitted from interactions with Karen Parkhill, Ben Wheeler, Stuart Capstick and Saffron OâNeill and feedback from participants at the Governing Sustainability workshop at the University of Sydney, March 2015, and the Royal Meteorological Society conference, London, November 2015. We further benefitted from helpful guidance from David Schlosberg and from two referees. This version remains our sole responsibility
Previously Claimed(/Unclaimed) X-ray Emission Lines in High Resolution Afterglow Spectra
We review the significance determination for emission lines in the Chandra
HETGS spectrum for GRB020813, and we report on a search for additional lines in
high resolution Chandra spectra. No previously unclaimed features are found. We
also discuss the significance of lines sets reportedly discovered using XMM
data for GRB011211 and GRB030227. We find that these features are likely of
modest, though not negligible, significance.Comment: 4 pages, 1 figures, to appear in Santa Fe GRB Conference Proceedings,
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