343 research outputs found
Tracking of toddler fruit and vegetable preferences to intake and adiposity later in childhood
This study examined whether toddlers' liking for fruit and vegetables (FV) predicts intake of FV later in childhood, how both relate to childhood adiposity and how these were moderated by factors in infancy. Children in the Gateshead Millennium Study were recruited at birth in 1999–2000. Feeding data collected in the first year were linked to data from a parental questionnaire completed for 456 children at age 2.5 years (30 m) and to anthropometry, skinfolds and bioelectrical impedance and 4‐day food diary data collected for 293 of these children at age 7 years. Aged 30 months, 50% of children were reported to like eight different vegetables and three fruits, but at 7 years, children ate a median of only 1.3 (range 0–7) portions of vegetables and 1.0 portion of fruit (0–4). Early appetite, feeding problems and food neophobia showed significant univariate associations with liking for FV aged 30 m, but the number of vegetables toddlers liked was the only independent predictor of vegetable consumption at age 7 years (odds ratio (OR) 1.28 p < 0.001). Liking for fruit aged 30 m also independently predicted fruit intake (OR = 1.31, p = 0.016), but these were also related to deprivation (OR = 2.69, p = 0.001) maternal education (OR = 1.28, p = 0.039) and female gender (OR = 1.8, p = 0.024). Children eating more FV at age 7 years had slightly lower body mass index and skinfolds. An early liking for FV predicted increased later intake, so increasing early exposure to FV could have long term beneficial consequences
Alternate operating methods for improving the performance of a continuous stirred tank reactor
The effect of the pumping direction of an axial flow impeller, the feeding rate and the number of feed inlets on
the operation of a continuously-fed stirred tank has been studied using CFD. The flow patterns generated by the
up-pumping and down-pumping impeller, under both ‘typical’ and ‘intensified’ operating conditions, are
compared. The effect of various tank configurations on the performance of the vessel is assessed by analysing
the flow and power numbers, as well as the concentration field of a non-reactive tracer. Furthermore, the inlet
feed jets are reduced using traditional jet similarity analysis and are compared with that of a typical round jet.
The results show that up-pumping impellers improve circulation in the upper part of the tank and reduce shortcircuiting
of the feed stream with only a small increase in power consumption. Furthermore, by using multiple
feed inlets to increase the total throughput capacity, the amplitude of torque fluctuations is decreased and
impeller bypassing is also decreased. The ensemble of conclusions suggest that the throughput capacity and
mixing quality of a CSTR can be improved, without problems of short-circuiting, by employing up-pumping
impellers coupled with multiple surface feed points
On the potential of the EChO mission to characterise gas giant atmospheres
Space telescopes such as EChO (Exoplanet Characterisation Observatory) and
JWST (James Webb Space Telescope) will be important for the future study of
extrasolar planet atmospheres. Both of these missions are capable of performing
high sensitivity spectroscopic measurements at moderate resolutions in the
visible and infrared, which will allow the characterisation of atmospheric
properties using primary and secondary transit spectroscopy. We use the NEMESIS
radiative transfer and retrieval tool (Irwin et al. 2008, Lee et al. 2012) to
explore the potential of the proposed EChO mission to solve the retrieval
problem for a range of H2-He planets orbiting different stars. We find that
EChO should be capable of retrieving temperature structure to ~200 K precision
and detecting H2O, CO2 and CH4 from a single eclipse measurement for a hot
Jupiter orbiting a Sun-like star and a hot Neptune orbiting an M star, also
providing upper limits on CO and NH3. We provide a table of retrieval
precisions for these quantities in each test case. We expect around 30
Jupiter-sized planets to be observable by EChO; hot Neptunes orbiting M dwarfs
are rarer, but we anticipate observations of at least one similar planet.Comment: 22 pages, 30 figures, 4 tables. Accepted for publication in MNRA
Exoplanet atmospheres with EChO: spectral retrievals using EChOSim
We demonstrate the effectiveness of the Exoplanet Characterisation
Observatory mission concept for constraining the atmospheric properties of hot
and warm gas giants and super Earths. Synthetic primary and secondary transit
spectra for a range of planets are passed through EChOSim (Waldmann & Pascale
2014) to obtain the expected level of noise for different observational
scenarios; these are then used as inputs for the NEMESIS atmospheric retrieval
code and the retrieved atmospheric properties (temperature structure,
composition and cloud properties) compared with the known input values,
following the method of Barstow et al. (2013a). To correctly retrieve the
temperature structure and composition of the atmosphere to within 2 {\sigma},
we find that we require: a single transit or eclipse of a hot Jupiter orbiting
a sun-like (G2) star at 35 pc to constrain the terminator and dayside
atmospheres; 20 transits or eclipses of a warm Jupiter orbiting a similar star;
10 transits/eclipses of a hot Neptune orbiting an M dwarf at 6 pc; and 30
transits or eclipses of a GJ1214b-like planet.Comment: 13 pages, 15 figures, 1 table. Accepted by Experimental Astronomy.
The final publication will shortly be available at Springer via
http://dx.doi.org/10.1007/s10686-014-9397-
From spectra to atmospheres: solving the underconstrained retrieval problem for exoplanets
Spectroscopic observations of transiting exoplanets have provided the first indications of their atmospheric structure and composition. Optimal estimation retrievals have been successfully applied to solar system planets to determine the temperature, composition and aerosol properties of their atmospheres, and have recently been applied to exoplanets. We show the effectiveness of the technique when combined with simulated observations from the proposed space telescope EChO, and also discuss the difficulty of constraining a complex system with sparse data and large uncertainties, using the super-Earth GJ 1214b as an exampl
The Transit Spectra of Earth and Jupiter
In recent years, a number of observations have been made of the transits of
'Hot Jupiters', such as HD 189733b, which have been modelled to derive
atmospheric structure and composition. As measurement techniques improve, the
transit spectra of 'Super-Earths' such as GJ 1214b are becoming better
constrained, allowing model atmospheres to be fitted for this class of planet
also. While it is not yet possible to constrain the atmospheric states of small
planets such as the Earth or cold planets like Jupiter, this may become
practical in the coming decades and if so, it is of interest to determine what
we might infer from such measurements. Here we have constructed atmospheric
models of the Solar System planets from 0.4 - 15.5 microns that are consistent
with ground-based and satellite observations and from these calculate the
primary transit and secondary eclipse spectra (with respect to the Sun and
typical M-dwarfs) that would be observed by a 'remote observer', many light
years away. From these spectra we test what current retrieval models might
infer about their atmospheres and compare these with the 'ground truths' in
order to assess: a) the inherent uncertainties in transit spectra observations;
b) the relative merits of primary transit and secondary eclipse spectra; and c)
the advantages of directly imaged spectra. We find that secondary eclipses
would not give sufficient information, but that primary transits give much
better determination. We find that a single transit of Jupiter in front of the
Sun could potentially be used to determine temperature and stratospheric
composition, but for the Earth the mean atmospheric composition could only be
determined if it were orbiting an M-dwarf. For both planets we note that direct
imaging with sufficient nulling of the light from the parent star provides the
best method of determining the atmospheric properties of such planets
The feasibility of developing multi-taxa indicators for landscape scale assessment of freshwater systems
The use of bird assemblages as wetland indicators is now well established in the UK. An indicator based on a single taxonomic group can, however, have limitations. Conversely, a multi-taxa approach can potentially provide a more robust reflection of the health of fresh waters. In this paper, we consider the inherent suitability of different taxonomic groups for inclusion in a multi-taxa indicator, based upon taxon characteristics, species richness and prevalence across a range of freshwater habitats, and their practical suitability, based upon quality and quantity of available data. We conclude that, in addition to birds, there are six candidate groups of taxa throughout the world that are currently suitable for inclusion in a multi-taxa indicator. These are: mammals, amphibians and reptiles, fish, dragonflies and damselflies (based on adult recording), benthic macroinvertebrates and macrophytes. Of these taxa, all but amphibians and reptiles and fish are suitable for inclusion in a UK indicator. The types and limitations of currently available datasets are reviewed. We provide recommendations for advancing this approach in the assessment of freshwater systems
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Specificity of Clinical Breast Examination in Community Practice
BACKGROUND: Millions of women receive clinical breast examination (CBE) each year, as either a breast cancer screening test or a diagnostic test for breast symptoms. While screening CBE had moderately high specificity (∼94%) in clinical trials, community clinicians may be comparatively inexperienced and may conduct relatively brief examinations, resulting in even higher specificity but lower sensitivity. OBJECTIVE: To estimate the specificity of screening and diagnostic CBE in clinical practice and identify patient factors associated with specificity. DESIGN: Retrospective cohort study. SUBJECTS: Breast-cancer-free female health plan enrollees in 5 states (WA, OR, CA, MA, and MN) who received CBE (N = 1,484). MEASUREMENTS: Medical charts were abstracted to ascertain breast cancer risk factors, examination purpose (screening vs diagnostic), and results (true-negative vs false-positive). Women were considered “average-risk” if they had neither a family history of breast cancer nor a prior breast biopsy and “increased-risk” otherwise. RESULTS: Among average- and increased-risk women, respectively, the specificity (true-negative proportion) of screening CBE was 99.4% [95% confidence interval (CI): 98.8–99.7%] and 97.1% (95% CI: 95.7–98.0%), and the specificity of diagnostic CBE was 68.7% (95% CI: 59.7–76.5%) and 57.1% (95% CI: 51.1–63.0%). The odds of a true-negative screening CBE (specificity) were significantly lower among women at increased risk of breast cancer (adjusted odds ratio 0.21; 95% CI: 0.10–0.46). CONCLUSIONS: Screening CBE likely has higher specificity among community clinicians compared to examiners in clinical trials of breast cancer screening, even among women at increased breast cancer risk. Highly specific examinations, however, may have relatively low sensitivity for breast cancer. Diagnostic CBE, meanwhile, is relatively nonspecific
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