10,942 research outputs found
NLTE 1.5D Modeling of Red Giant Stars
Spectra for 2D stars in the 1.5D approximation are created from synthetic
spectra of 1D non-local thermodynamic equilibrium (NLTE) spherical model
atmospheres produced by the PHOENIX code. The 1.5D stars have the spatially
averaged Rayleigh-Jeans flux of a K3-4 III star, while varying the temperature
difference between the two 1D component models (),
and the relative surface area covered. Synthetic observable quantities from the
1.5D stars are fitted with quantities from NLTE and local thermodynamic
equilibrium (LTE) 1D models to assess the errors in inferred
values from assuming horizontal homogeneity and LTE. Five different quantities
are fit to determine the of the 1.5D stars: UBVRI
photometric colors, absolute surface flux SEDs, relative SEDs, continuum
normalized spectra, and TiO band profiles. In all cases except the TiO band
profiles, the inferred value increases with increasing
. In all cases, the inferred value
from fitting 1D LTE quantities is higher than from fitting 1D NLTE quantities
and is approximately constant as a function of
within each case. The difference between LTE and NLTE for the TiO bands is
caused indirectly by the NLTE temperature structure of the upper atmosphere, as
the bands are computed in LTE. We conclude that the difference between
values derived from NLTE and LTE modelling is relatively
insensitive to the degree of the horizontal inhomogeneity of the star being
modeled, and largely depends on the observable quantity being fit.Comment: 46 pages, 14 figures, 7 tables, accepted for publication in ApJ on
April 5, 201
NLTE and LTE Lick indices for red giants from [M/H] 0.0 to -6.0 at SDSS and IDS spectral resolution
We investigate the dependence of the complete system of 22 Lick indices on
overall metallicity scaled from solar abundances, [M/H], from the solar value,
0.0, down to the extremely-metal-poor (XMP) value of -6.0, for late-type giant
stars (MK luminosity class III, log(g)=2.0) of MK spectral class late-K to
late-F (3750 < Teff < 6500 K) of the type that are detected as "fossils" of
early galaxy formation in the Galactic halo and in extra-galactic structures.
Our investigation is based on synthetic index values, I, derived from
atmospheric models and synthetic spectra computed with PHOENIX in LTE and
Non-LTE (NLTE), where the synthetic spectra have been convolved to the spectral
resolution, R, of both IDS and SDSS (and LAMOST) spectroscopy. We identify nine
indices, that we designate "Lick-XMP", that remain both detectable and
significantly [M/H]-dependent down to [M/H] values of at least ~-5.0, and down
to [M/H] ~ -6.0 in five cases, while also remaining well-behaved . For these
nine, we study the dependence of I on NLTE effects, and on spectral resolution.
For our LTE I values for spectra of SDSS resolution, we present the fitted
polynomial coefficients, C_n, from multi-variate linear regression for I with
terms up to third order in the independent variable pairs (Teff, [M/H]), and
(V-K, [M/H]), and compare them to the fitted C_n values of Worthey et al.
(1994) at IDS spectral resolution.Comment: Accepted for publication in the Astrophysical Journal. Tables 6 and 7
available electronically from the autho
The Human Right to Water and Unconventional Energy
Access to water, in sufficient quantities and of sufficient quality is vital for human health. The United Nations Committee on Economic, Social and Cultural Rights (in General Comment 15, drafted 2002) argued that access to water was a condition for the enjoyment of the right to an adequate standard of living, inextricably related to the right to the highest attainable standard of health, and thus a human right. On 28 July 2010 the United Nations General Assembly declared safe and clean drinking water and sanitation a human right essential to the full enjoyment of life and all other human rights. This paper charts the international legal development of the right to water and its relevance to discussions surrounding the growth of unconventional energy and its heavy reliance on water. We consider key data from the country with arguably the most mature and extensive industry, the USA, and highlight the implications for water usage and water rights. We conclude that, given the weight of testimony of local people from our research, along with data from scientific literature, non-governmental organization (NGO) and other policy reports, that the right to water for residents living near fracking sites is likely to be severely curtailed. Even so, from the data presented here, we argue that the major issue regarding water use is the shifting of the resource from society to industry and the demonstrable lack of supply-side price signal that would demand that the industry reduce or stabilize its water demand per unit of energy produced. Thus, in the US context alone, there is considerable evidence that the human right to water will be seriously undermined by the growth of the unconventional oil and gas industry, and given its spread around the globe this could soon become a global human rights issue
Automation of surface observations program
At present, surface weather observing methods are still largely manual and labor intensive. Through the nationwide implementation of Automated Surface Observing Systems (ASOS), this situation can be improved. Two ASOS capability levels are planned. The first is a basic-level system which will automatically observe the weather parameters essential for aviation operations and will operate either with or without supplemental contributions by an observer. The second is a more fully automated, stand-alone system which will observe and report the full range of weather parameters and will operate primarily in the unattended mode. Approximately 250 systems are planned by the end of the decade. When deployed, these systems will generate the standard hourly and special long-line transmitted weather observations, as well as provide continuous weather information direct to airport users. Specific ASOS configurations will vary depending upon whether the operation is unattended, minimally attended, or fully attended. The major functions of ASOS are data collection, data processing, product distribution, and system control. The program phases of development, demonstration, production system acquisition, and operational implementation are described
Isbourne Catchment Community Report: Potential for Natural Flood Management in the Catchment
The School of Natural and Social Sciences (SNSS) and the Countryside and Communities Research Institute (CCRI) at the University of Gloucestershire were commissioned by the Isbourne Catchment Group (ICG) and the Environment Agency (EA) to undertake an initial assessment of the River Isbourne to determine the feasibility and potential benefits of applying natural flood management (NFM) techniques across the Isbourne catchment. Other engineering options had been considered in an analysis of the catchment in 2010 (Haycock 2010) and some minor changes have been made by the EA in the last few years. However, most significant engineering options were not considered to be cost effective whilst soft engineering options such as land use change and natural flood management were recommended for further investigation, which is the focus of this report – no assessment of hard engineering possibilities are made in this report as it is beyond the remit of the investigation. The report describes the catchment characteristics, gives an overview of potential NFM options and provides recommendations of which of these could be implemented in the catchments and ways forward
Mesocosm experiments quantify the effects of eutrophication on eelgrass, Zostera marina
Outdoor mesocosm experiments were used to examine the response of eelgrass communities to excess nutrient loading and reduced light that simulated coastal eutrophication. A series of replicated manipulations conducted between 1988 and 1990 demonstrated the effects of reduced available light and increased loading of nitrogen plus phosphorus on habitats dominated by eelgrass Zostera marina L. Shade and nutrients each significantly affected eelgrass growth, morphology, density, and biomass. We found no significant interactions between the effects of shade and the effects of nutrients on any plant characteristics except leaf length. The growth rate of individual eelgrass shoots was linearly related to light, increasing throughout the range of available light. Biomass and daily biomass increase, or areal growth, were also linearly related to light, but specific growth showed no response to light. Shoot density increased with the log of light. Excess nutrient loading was shown to significantly reduce eelgrass growth and bed structure through stimulation of various forms of algae that effectively competed with eelgrass for light. The absence of significant interactions between the effects of shade and nutrients on eelgrass density, growth, and biomass suggests that the negative effect of algae on eelgrass occurs primarily through the reduction of light (i.e. shading). The outcome of nutrient enrichment was a shift in plant dominance from eelgrass to three algal forms: phytoplankton, epiphytic algae, and macroalgae. We quantified the effects of eutrophication and demonstrated that increased nutrient loading results in less light for eelgrass and that eelgrass growth linearly decreases with reduced light
Development of a Priest interferometer for measurement of the thermal expansion of a graphite epoxy in the temperature range 116-366 K
The thermal expansion behavior of graphite epoxy laminates between 116 and 366 degrees Kelvin was investigated using as implementation of the Priest interferometer concept. The design, construction and use of the interferometer along with the experimental results it was used to generate are described. The experimental program consisted of 25 tests on 25.4 mm and 6.35 mm wide, 8 ply pi/4 quasi-isotropic T300-5208 graphite/epoxy specimens and 3 tests on a 25.4 mm wide unidirectional specimen. Experimental results are presented for all tests along with a discussion of the interferometer's limitations and some possible improvements in its design
Surface disinfection challenges for Candida auris: an in-vitro study
The emerging pathogenic multidrug-resistant yeast Candida auris is an important source of healthcare-associated infections and of growing global clinical concern. The ability of this organism to survive on surfaces and withstand environmental stressors creates a challenge for eradicating it from hospitals. A panel of C. auris clinical isolates was evaluated on different surface environments against the standard disinfectant sodium hypochlorite and high-level disinfectant peracetic acid. C. auris was shown to selectively tolerate clinically relevant concentrations of sodium hypochlorite and peracetic acid in a surface-dependent manner, which may explain its ability to successfully persist within the hospital environment
Thermal expansion of graphite-epoxy between 116 K and 366 K
A Priest laser interferometer was developed to measure the thermal strain of composite laminates. The salient features of this interferometer are that: (1) it operates between 116 K and 366 K; (2) it is easy to operate; (3) minimum specimen preparation is required; (4) coefficients of thermal expansion in the range of 0-5 micro epsilon/K can be measured; and (5) the resolution of thermal strain is on the order of micro epsilon. The thermal response of quasi-isotropic, T300/5208, grahite-epoxy composite material was studied with this interferometer. The study showed that: (1) for the material tested, thermal cycling effects are negligible; (2) variability of thermal response from specimen to specimen may become significant at cryogenic temperatures; and (3) the thermal response of 0.6 cm and 2.5 cm wide specimens are the same above room temperature
- …
