203,789 research outputs found
Xenon in Mercury-Manganese Stars
Previous studies of elemental abundances in Mercury-Manganese (HgMn) stars
have occasionally reported the presence of lines of the ionized rare noble gas
Xe II, especially in a few of the hottest stars with Teff ~ 13000--15000 K. A
new study of this element has been undertaken using observations from Lick
Observatory's Hamilton Echelle Spectrograph. In this work, the spectrum
synthesis program UCLSYN has been used to undertake abundance analysis assuming
LTE. We find that in the Smith & Dworetsky sample of HgMn stars, Xe is vastly
over-abundant in 21 of 22 HgMn stars studied, by factors of 3.1--4.8 dex. There
does not appear to be a significant correlation of Xe abundance with Teff. A
comparison sample of normal late B stars shows no sign of Xe II lines that
could be detected, consistent with the expected weakness of lines at normal
abundance. The main reason for the previous lack of widespread detection in
HgMn stars is probably due to the strongest lines being at longer wavelengths
than the photographic blue. The lines used in this work were 4603.03A, 4844.33A
and 5292.22A.Comment: 8 pages, 4 figures. Accepted by Monthly Notices of the Royal
Astronomical Society, 8 January 200
National evaluation of the neighbourhood nurseries: integrated report
Report description: The NNI was launched in 2001 to provide high quality childcare in the most disadvantaged neighbourhoods of England, to help parents into employment, reduce child poverty and boost children’s development. By 2005 45,000 new childcare places had been created in approximately 1,400 neighbourhood nurseries.
This report brings together the findings of the four individual strands of the National Evaluation of Neighbourhood Nurseries Initiative as shown above and makes a number of recommendations.
The report shows the rationale for the government’s strategy in targeting disadvantaged neighbourhoods and in focusing on high quality childcare to provide the link between raising parental employment and income and improving children’s life chances
Temperature perturbation model of the opto-galvanic effect in CO2-laser discharges
A detailed discharge model of the opto-galvanic effect in molecular laser gas mixtures is developed based on the temperature perturbation or discharge cooling mechanism of Smith and Brooks (1979). Excellent agreement between the model and experimental results in CO2 laser gas mixtures is obtained. The model should be applicable to other molecular systems where the OGE is being used for laser stabilisation and as a spectroscopic tool
Competition and cooperation in one-dimensional stepping stone models
Cooperative mutualism is a major force driving evolution and sustaining
ecosystems. Although the importance of spatial degrees of freedom and number
fluctuations is well-known, their effects on mutualism are not fully
understood. With range expansions of microbes in mind, we show that, even when
mutualism confers a distinct selective advantage, it persists only in
populations with high density and frequent migrations. When these parameters
are reduced, mutualism is generically lost via a directed percolation process,
with a phase diagram strongly influenced by an exceptional DP2 transition.Comment: 8 pages, 4 figure
Arresting woodland bird decline in Australian agricultural landscapes: potential application of the European agri-environment model
This paper considered the applicability of the European model of land stewardship payments, in particular its support for biodiversity conservation in agricultural landscapes, to an Australian context. More broadly, the research approach described in the paper may also be applied to assessing the suitability of overseas stewardship schemes to the provision of any ecoservice in
Australia, such as carbon sequestration and floodwater regulation
Rate constants and Arrhenius parameters for the reactions of OH radicals and Cl atoms with CF3CH2OCHF2, CF3CHClOCHF2 and CF3CH2OCClF2, using the discharge-flow/resonance fluorescence method
Rate constants have been determined for the reactions of OH radicals and Cl atoms with the three partially halogenated methyl-ethyl ethers, CFCHOCHF, CFCHClOCHF and CFCHOCClF, using discharge-flow techniques to generate the OH radicals and the Cl atoms and resonance fluorescence to observe changes in their relative concentrations in the presence of added ether. For each combination of radical and ether, experiments were carried out at three temperatures between 292 and 410 K, yielding the following Arrhenius expressions for the rate constants within this range of temperature:
OH + CFCHOCHF: = (2.00.8) 10 exp( – 2110 150 K / T) cm molecule s
OH + CFCHClOCHF: = (4.5 1.3) 10 exp( – 940 100 K / T) cm molecule s
OH + CFCHOCClF: = (1.6 0.6) 10 exp( – 1100 125 K / T) cm molecule s
Cl + CFCHOCHF: = (6.1 1.4) 10 exp( – 1830 90 K / T) cm molecule s
Cl + CFCHClOCHF: = (7.8 2.6) 10 exp( – 2980 130 K / T) cm molecule s
Cl + CFCHOCClF: = (2.2 0.2) 10 exp( – 2700 40 K / T) cm molecule s
The results are compared with those obtained previously for the same and related reactions of OH radicals and Cl atoms, and the atmospheric implications of the results are considered briefly
Addressing health literacy in patient decision aids
MethodsWe reviewed literature for evidence relevant to these two aims. When high-quality systematic reviews existed, we summarized their evidence. When reviews were unavailable, we conducted our own systematic reviews.ResultsAim 1: In an existing systematic review of PtDA trials, lower health literacy was associated with lower patient health knowledge (14 of 16 eligible studies). Fourteen studies reported practical design strategies to improve knowledge for lower health literacy patients. In our own systematic review, no studies reported on values clarity per se, but in 2 lower health literacy was related to higher decisional uncertainty and regret. Lower health literacy was associated with less desire for involvement in 3 studies, less question-asking in 2, and less patient-centered communication in 4 studies; its effects on other measures of patient involvement were mixed. Only one study assessed the effects of a health literacy intervention on outcomes; it showed that using video to improve the salience of health states reduced decisional uncertainty. Aim 2: In our review of 97 trials, only 3 PtDAs overtly addressed the needs of lower health literacy users. In 90% of trials, user health literacy and readability of the PtDA were not reported. However, increases in knowledge and informed choice were reported in those studies in which health literacy needs were addressed.ConclusionLower health literacy affects key decision-making outcomes, but few existing PtDAs have addressed the needs of lower health literacy users. The specific effects of PtDAs designed to mitigate the influence of low health literacy are unknown. More attention to the needs of patients with lower health literacy is indicated, to ensure that PtDAs are appropriate for lower as well as higher health literacy patients
Seyfert Galaxies in the Local Universe: Analysis of Spitzer Spectra of a Complete Sample
The Spitzer high resolution spectra of 72 Seyfert galaxies from the 12m
Galaxy Sample are presented and discussed. The presence of starburst components
in these galaxies can be quantified by powerful mid-IR diagnostics tools (i.e.
11.25m PAH feature equivalent width and the H emission line
intensity), as well as the AGN dominance can be measured by specific fine
structure line ratios (e.g. [NeV]/[NeII], [NeV]/[SiII], etc.). The two types of
Seyfert galaxies do not show any statistical difference in our diagnostic
tools. However, the Seyfert 2's showing hidden Broad Line Regions in
spectro-polarimetric observations have on average an higher AGN dominance, a
weaker star formation component and a warmer [60 - 25] spectral index than
those without broad emission lines.Comment: Proceedings of the Conference "The central kiloparsec. Active
Galactic Nuclei and their hosts, 4-6 June 2008, Ierapetra, Crete, Greec
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