8,780 research outputs found
STIS Longslit Spectroscopy Of The Narrow Line Region Of NGC 4151. I. Kinematics and Emission Line Ratios
Longslit spectra of the Seyfert galaxy NGC 4151 from the UV to near infrared
have been obtained with STIS to study the kinematics and physical conditions in
the NLR. The kinematics show evidence for three components, a low velocity
system in normal disk rotation, a high velocity system in radial outflow at a
few hundred km/s relative to the systemic velocity and an additional high
velocity system also in outflow with velocities up to 1400 km/s, in agreement
with results from STIS slitless spectroscopy (Hutchings et al., 1998, Kaiser et
al., 1999, Hutchings et al., 1999) We have explored two simple kinematic models
and suggest that radial outflow in the form of a wind is the most likely
explanation. We also present evidence indicating that the wind may be
decelerating with distance from the nucleus.
We find that the emission line ratios along our slits are all entirely
consistent with photoionization from the nuclear continuum source. A decrease
in the [OIII]5007/H-beta and [OIII]5007/[OII]3727 ratios suggests that the
density decreases with distance from the nucleus. This trend is borne out by
the [SII] ratios as well. We find no strong evidence for interaction between
the radio jet and the NLR gas in either the kinematics or the emission line
ratios in agreement with the results of Kaiser et al. (1999) who find no
spatial coincidence of NLR clouds and knots in the radio jet. These results are
in contrast to other recent studies of nearby AGN which find evidence for
significant interaction between the radio source and the NLR gas.Comment: 32 pages, 13 figures, accepted for publication in The Astrophysical
Journa
Metalanguage in L1 English-speaking 12-year-olds: which aspects of writing do they talk about?
Traditional psycholinguistic approaches to metalinguistic awareness in L1 learners elicit responses containing metalanguage that demonstrates metalinguistic awareness
of pre-determined aspects of language knowledge. This paper, which takes a more ethnographic approach, demonstrates how pupils are able to engage their own focus of metalanguage when reflecting on their everyday learning activities involving written language. What is equally significant is what their metalanguage choices reveal about
their understanding and application of written language concepts
Meningococcal disease in children in Merseyside, England:a 31 year descriptive study
Meningococcal disease (MCD) is the leading infectious cause of death in early childhood in the United Kingdom, making it a public health priority. MCD most commonly presents as meningococcal meningitis (MM), septicaemia (MS), or as a combination of the two syndromes (MM/MS). We describe the changing epidemiology and clinical presentation of MCD, and explore associations with socioeconomic status and other risk factors. A hospital-based study of children admitted to a tertiary children's centre, Alder Hey Children's Foundation Trust, with MCD, was undertaken between 1977 to 2007 (n = 1157). Demographics, clinical presentations, microbiological confirmation and measures of deprivation were described. The majority of cases occurred in the 1-4 year age group and there was a dramatic fall in serogroup C cases observed with the introduction of the meningococcal C conjugate (MCC) vaccine. The proportion of MS cases increased over the study period, from 11% in the first quarter to 35% in the final quarter. Presentation with MS (compared to MM) and serogroup C disease (compared to serogroup B) were demonstrated to be independent risk factors for mortality, with odds ratios of 3.5 (95% CI 1.18 to 10.08) and 2.18 (95% CI 1.26 to 3.80) respectively. Cases admitted to Alder Hey were from a relatively more deprived population (mean Townsend score 1.25, 95% CI 1.09 to 1.41) than the Merseyside reference population. Our findings represent one of the largest single-centre studies of MCD. The presentation of MS is confirmed to be a risk factor of mortality from MCD. Our study supports the association between social deprivation and MCD
Nuttier (A)dS Black Holes in Higher Dimensions
We construct new solutions of the vacuum Einstein field equations with
cosmological constant. These solutions describe spacetimes with non-trivial
topology that are asymptotically dS, AdS or flat. For a negative cosmological
constant these solutions are NUT charged generalizations of the topological
black hole solutions in higher dimensions. We also point out the existence of
such NUT charged spacetimes in odd dimensions and we explicitly construct such
spaces in 5 and 7 dimensions. The existence of such spacetimes with non-trivial
topology is closely related to the existence of the cosmological constant.
Finally, we discuss the global structure of such solutions and possible
applications in string theory.Comment: latex, 30 pages, added reference
Impacts of the 2008 Great Recession on dietary intake: a systematic review and meta-analysis
Background The 2008 Great Recession significantly impacted economies and individuals globally, with potential impacts on food systems and dietary intake. We systematically reviewed evidence on the impact of the Great Recession on individualsâ dietary intake globally and whether disadvantaged individuals were disproportionately affected. Methods We searched seven databases and relevant grey literature through June 2020. Longitudinal quantitative studies with the 2008 recession as the exposure and any measure of dietary intake (energy intake, dietary quality, and food/macronutrient consumption) as the outcome were eligible for inclusion. Eligibility was independently assessed by two reviewers. The Newcastle Ottawa Scale was used for quality and risk of bias assessment. We undertook a random effects meta-analysis for changes in energy intake. Harvest plots were used to display and summarise study results for other outcomes. The study was registered with PROSPERO (CRD42019135864). Results Forty-one studies including 2.6 million people met our inclusion criteria and were heterogenous in both methods and results. Ten studies reported energy intake, 11 dietary quality, 34 food intake, and 13 macronutrient consumption. The Great Recession was associated with a mean reduction of 103.0âcal per adult equivalent per day (95% Confidence Interval: ââ132.1, ââ73.9) in high-income countries (5 studies) and an increase of 105.5âcal per adult per day (95% Confidence Interval: 72.8, 138.2) in middle-income countries (2 studies) following random effects meta-analysis. We found reductions in fruit and vegetable intake. We also found reductions in intake of fast food, sugary products, and soft drinks. Impacts on macronutrients and dietary quality were inconclusive, though suggestive of a decrease in dietary quality. The Great Recession had greater impacts on dietary intake for disadvantaged individuals. Conclusions The 2008 recession was associated with diverse impacts on diets. Calorie intake decreased in high income countries but increased in middle income countries. Fruit and vegetable consumption reduced, especially for more disadvantaged individuals, which may negatively affect health. Fast food, sugary products, and soft drink consumption also decreased which may confer health benefits. Implementing effective policies to mitigate adverse nutritional changes and encourage positive changes during the COVID-19 pandemic and other major economic shocks should be prioritised
'Surely the most natural scenario in the worldâ: Representations of âFamilyâ in BBC Pre-school Television
Historically, the majority of work on British childrenâs television has adopted either an institutional or an audience focus, with the texts themselves often overlooked. This neglect has meant that questions of representation in British childrenâs television â including issues such as family, gender, class or ethnicity - have been infrequently analysed in the UK context. In this article, we adopt a primarily qualitative methodology and analyse the various textual manifestations of âfamilyâ, group, or community as represented in a selected number of BBC pre-school programmes. In doing so, we question the (limited amount of) international work that has examined representations of the family in childrenâs television, and argue that nuclear family structures do not predominate in this sphere
HST FOC spectroscopy of the NLR of NGC 4151. I. Gas kinematics
We present the results from a detailed kinematic analysis of both
ground-based, and Hubble Space Telescope/Faint Object Camera long-slit
spectroscopy at sub-arcsec spatial resolution, of the narrow-line region of NGC
4151. In agreement with previous work, the extended emission gas (R > 4") is
found to be in normal rotation in the galactic plane, a behaviour that we were
able to trace even across the nuclear region, where the gas is strongly
disturbed by the interaction with the radio jet, and connects smoothly with the
large scale rotation defined by the neutral gas emission. The HST data, at
0.029" spatial resolution, allow us for the first time to truly isolate the
kinematic behaviour of the individual clouds in the inner narrow-line region.
We find that, underlying the perturbations introduced by the radio ejecta, the
general velocity field can still be well represented by planar rotation down to
a radius of ~ 0.5" (30 pc), distance at which the rotation curve has its
turnover.
The most striking result that emerges from our analysis is that the galaxy
potential derived fitting the rotation curve changes from a "dark halo" at the
ENLR distances to dominated by the central mass concentration in the NLR, with
an almost Keplerian fall-off in the 1"< R < 4" interval. The observed velocity
of the gas at 0.5" implies a mass of M ~ 10E9 M(sol) within the inner 60 pc.
The presence of a turnover in the rotation curve indicates that this central
mass concentration is extended. The first measured velocity point (outside the
region saturated by the nucleus) would imply an enclosed mass of ~ 5E7 M(sol)
within R ~ 0.15" (10 pc) which represents an upper limit to any nuclear point
mass.Comment: 30 pages (aaspp4.sty), 14 figures. Fig. 1, 2 and 4 available by
anonymous FTP at 143.54.2.51 (cd /pub/winge) as GIF files; or upon request to
[email protected]. Accepted for publication in the Astrophysical Journal
(part 1
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