735 research outputs found
Effectiveness of a social support intervention on infant feeding practices : randomised controlled trial
Background: To assess whether monthly home visits from trained volunteers could improve infant feeding practices at age 12 months, a randomised controlled trial was carried out in two disadvantaged inner city London boroughs.
Methods: Women attending baby clinics with their infants (312) were randomised to receive monthly home visits from trained volunteers over a 9-month period (intervention group) or standard professional care only (control group). The primary outcome was vitamin C intakes from fruit. Secondary outcomes included selected macro and micro-nutrients, infant feeding habits, supine length and weight. Data were collected at baseline when infants were aged approximately 10 weeks, and subsequently when the child was 12 and 18 months old.
Results: Two-hundred and twelve women (68%) completed the trial. At both follow-up points no significant differences were found between the groups for vitamin C intakes from fruit or other nutrients. At first follow-up, however, infants in the intervention group were significantly less likely to be given goats’ or soya milks, and were more likely to have three solid meals per day. At the second follow-up, intervention group children were significantly less likely to be still using a bottle. At both follow-up points, intervention group children also consumed significantly more specific fruit and vegetables.
Conclusions: Home visits from trained volunteers had no significant effect on nutrient intakes but did promote some other recommended infant feeding practices
Control of Raman Lasing in the Nonimpulsive Regime
We explore coherent control of stimulated Raman scattering in the
nonimpulsive regime. Optical pulse shaping of the coherent pump field leads to
control over the stimulated Raman output. A model of the control mechanism is
investigated.Comment: 4 pages, 5 figure
Extracting quantum dynamics from genetic learning algorithms through principal control analysis
Genetic learning algorithms are widely used to control ultrafast optical
pulse shapes for photo-induced quantum control of atoms and molecules. An
unresolved issue is how to use the solutions found by these algorithms to learn
about the system's quantum dynamics. We propose a simple method based on
covariance analysis of the control space, which can reveal the degrees of
freedom in the effective control Hamiltonian. We have applied this technique to
stimulated Raman scattering in liquid methanol. A simple model of two-mode
stimulated Raman scattering is consistent with the results.Comment: 4 pages, 5 figures. Presented at coherent control Ringberg conference
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The future of the oceans past : toward a global marine historical research initiative
Historical research is playing an increasingly important role in marine sciences. Historical data are also used in policy making and marine resource management, and have helped to address the issue of shifting baselines for numerous species and ecosystems. Although many important research questions still remain unanswered, tremendous developments in conceptual and methodological approaches are expected to contribute to a comprehensive understanding of the global history of human interactions with life in the seas. Based on our experiences and knowledge from the "History of Marine Animal Populations' project, this paper identifies the emerging research topics for future historical marine research. It elaborates on concepts and tools which are expected to play a major role in answering these questions, and identifies geographical regions which deserve future attention from marine environmental historians and historical ecologists
Exploring The Frequency Of Close-In Jovian Planets Around M Dwarfs
We discuss our high precision radial velocity results of a sample of 90 M dwarfs observed with the Hobby-Eberly Telescope and the Harlan J. Smith 2.7 m Telescope at McDonald Observatory, as well as the ESO VLT and the Keck I telescopes, within the context of the overall frequency of Jupiter-mass planetary companions to main sequence stars. None of the stars in our sample show variability indicative of a giant planet in a short period orbit, with a 3.8 M_Jup and a 3.5 M_Jup and a < 0.7 AU. Our results point toward a generally lower frequency of close-in Jovian planets for M dwarfs as compared to FGK-type stars. This is an important piece of information for our understanding of the process of planet formation as a function of stellar mass
Surface abundances of light elements for a large sample of early B-type stars - IV. The magnesium abundance in 52 stars - a test of metallicity
From high-resolution spectra a non-LTE analysis of the MgII 4481.2 A feature
is implemented for 52 early and medium local B stars on the main sequence (MS).
The influence of the neighbouring line AlIII 4479.9 A is considered. The
magnesium abundance is determined; it is found that log e(Mg) = 7.67 +- 0.21 on
average. It is shown that uncertainties in the microturbulent parameter Vt are
the main source of errors in log e(Mg). When using 36 stars with the most
reliable Vt values derived from OII and NII lines, we obtain the mean abundance
log e(Mg) = 7.59 +- 0.15. The latter value is precisely confirmed for several
hot B stars from an analysis of the MgII 7877 A weak line. The derived
abundance log e(Mg) = 7.59 +- 0.15 is in excellent agreement with the solar
magnesium abundance log e_sun(Mg) = 7.55 +- 0.02, as well as with the proto-Sun
abundance log e_ps(Mg) = 7.62 +- 0.02. Thus, it is confirmed that the Sun and
the B-type MS stars in our neighbourhood have the same metallicity.Comment: 9 pages, 6 figures. Has been accepted for publication at MNRA
Accurate Fundamental Parameters or A, F, and G-type Supergiants in the Solar Neighbourhood
The following parameters are determined for 63 Galactic supergiants in the
solar neighbourhood: effective temperature Teff, surface gravity log g, iron
abundance log e(Fe), microturbulent parameter Vt, mass M/Msun, age t and
distance d. A significant improvement in the accuracy of the determination of
log g and, all parameters dependent on it, is obtained through application of
van Leeuwens (2007) re-reduction of the Hipparcos parallaxes. The typical error
in the log g values is now +-0.06 dex for supergiants with distances d < 300 pc
and +-0.12 dex for supergiants with d between 300 and 700 pc; the mean error in
Teff for these stars is +-120 K. For supergiants with d > 700 pc parallaxes are
uncertain or unmeasurable, so typical errors in their log g values are 0.2-0.3
dex.
A new Teff scale for A5-G5 stars of luminosity classes Ib-II is presented.
Spectral subtypes and luminosity classes of several stars are corrected.
Combining the Teff and log g with evolutionary tracks, stellar masses and ages
are determined; a majority of the sample has masses between 4 Msun and 15 Msun
and, hence, their progenitors were early to middle B-type main sequence stars.
Using Fe ii lines, which are insensitive to departures from LTE, the
microturbulent parameter Vt and the iron abundance log e(Fe) are determined
from high-resolution spectra. The parameter Vt is correlated with gravity: Vt
increases with decreasing log g. The mean iron abundance for the 48 supergiants
with distances d < 700 pc is log e(Fe)=7.48+-0.09, a value close to the solar
value of 7.45+-0.05, and thus the local supergiants and the Sun have the same
metallicity.Comment: 12 pages, 9 figures. Will be published at MNRA
Detailed analysis of Balmer lines in cool dwarf stars
An analysis of H alpha and H beta spectra in a sample of 30 cool dwarf and
subgiant stars is presented using MARCS model atmospheres based on the most
recent calculations of the line opacities. A detailed quantitative comparison
of the solar flux spectra with model spectra shows that Balmer line profile
shapes, and therefore the temperature structure in the line formation region,
are best represented under the mixing length theory by any combination of a low
mixing-length parameter alpha and a low convective structure parameter y. A
slightly lower effective temperature is obtained for the sun than the accepted
value, which we attribute to errors in models and line opacities. The programme
stars span temperatures from 4800 to 7100 K and include a small number of
population II stars. Effective temperatures have been derived using a
quantitative fitting method with a detailed error analysis. Our temperatures
find good agreement with those from the Infrared Flux Method (IRFM) near solar
metallicity but show differences at low metallicity where the two available
IRFM determinations themselves are in disagreement. Comparison with recent
temperature determinations using Balmer lines by Fuhrmann (1998, 2000), who
employed a different description of the wing absorption due to self-broadening,
does not show the large differences predicted by Barklem et al. (2000). In
fact, perhaps fortuitously, reasonable agreement is found near solar
metallicity, while we find significantly cooler temperatures for low
metallicity stars of around solar temperature.Comment: 17 pages, 9 figures, to appear in A&
Kepler-424 b: A "lonely" hot Jupiter that found a companion
Peer reviewedFinal Accepted Versio
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