117 research outputs found
Breeding for meat quality in pigs
The aim of this study was to investigate the possibilities of improving pig meat quality by selection. Therefore, literature is reviewed to determine the meat quality traits to be used and genetic parameters of those meat quality traits are calculated. A method is described to obtain marginal- income functions and economic values of meat quality traits. At last, consequences of including meat quality in the breeding goal for the various tiers of the pig meat production chain are analyzed. It is concluded that there are possibilities to improve meat quality by selection. Three strategies to improve meat quality by breeding are described. Effects of the various strategies on the genetic improvement of both production and meat quality traits are examined. Which strategy has to be used will depend on the current levels of the meat quality traits of the commercial pigs
Quasiparticle relaxation in optically excited high-Q superconducting resonators
The quasiparticle relaxation time in superconducting films has been measured
as a function of temperature using the response of the complex conductivity to
photon flux. For tantalum and aluminium, chosen for their difference in
electron-phonon coupling strength, we find that at high temperatures the
relaxation time increases with decreasing temperature, as expected for
electron-phonon interaction. At low temperatures we find in both
superconducting materials a saturation of the relaxation time, suggesting the
presence of a second relaxation channel not due to electron-phonon interaction.Comment: 4 pages, 3 figure
Chronic consumers of boiled coffee have elevated serum levels of lipoprotein(a)
OBJECTIVES: Lipoprotein(a) consists of an LDL-particle attached to apolipoprotein(a), which is made by the liver. Diterpenes present in boiled coffee raise serum levels of LDL cholesterol and of the liver enzyme alanine aminotransferase in man. We investigated the association between intake of boiled coffee and serum levels of lipoprotein(a). DESIGN, SETTING AND SUBJECTS: Healthy Norwegians 40-42 years of age, who habitually consumed five or more cups of boiled coffee per day (n = 150) were compared with matched filter coffee consumers (n = 159) in a cross-sectional study, as part of the Norwegian National Health Screening in 1992. RESULTS: The median lipoprotein(a) level was 13.0 mg dL-1 (10th and 90th percentile: 2.5 and 75.0 mg dL-1, respectively) on boiled and 7.9 mg dL-1 (10th and 90th percentile: 1.9 and 62.5 mg dL-1, respectively) on filter coffee (P = 0.048). Means /- SE were 25.8 /- 2.4 mg dL-1 and 19.6 /- 2.0 mg dL-1, respectively (P = 0.04). Although not statistically significant, subjects consuming nine or more cups of coffee per day had higher lipoprotein(a) levels than those drinking five to eight cups per day in both coffee groups. CONCLUSION: Chronic consumers of unfiltered, boiled coffee have higher serum levels of lipoprotein(a) than filter coffee drinkers
Diterpenes from coffee beans decrease serum levels of lipoprotein(a) in humans: results from four randomized controlled trials
Objective: Unfiltered coffee raises serum LDL cholesterol in humans, owing to the presence of the diterpenes cafestol and kahweol. Norwegians with a chronic high intake of unfiltered coffee also had elevated serum levels of lipoprotein(a), an LDL-like particle which is insensitive toward dietary interventions. We now experimentally studied the influence of coffee diterpenes on lipoprotein(a) levels. Design: Four randomised controlled trials. Subjects: Healthy, normolipidemic volunteers. Interventions: Coffee, coffee oil, and pure diterpenes for 4-24 weeks. Main outcome measures: The circulating level of lipoprotein(a). Results: In 22 subjects drinking five to six strong cups of cafetiere coffee per day, the median fall in lipoprotein(a) was 1.5 mg/dL after two months (P=0.03), and 0.5 mg/dL after half a year (P>0.05), relative to 24 filter coffee drinkers. Coffee oil doses equivalent to 10-20 cups of unfiltered coffee reduced lipoprotein(a) levels by up to 5.5 mg/dL (P<0.05) in two separate trials (n=12-16 per group). A purified mixture of cafestol and kahweol, as well as cafestol alone, were also effective in reducing Lp(a) levels (n=10). Averaged over the four trials, each 10 mg/d of cafestol (plus kahweol)?the amount present in two to three cups of cafetiere coffee?decreased Lp(a) levels by 0.5 mg/dL or 4% from baseline values after four weeks (n=63). Conclusions: Coffee diterpenes are among the few dietary exceptions shown to influence serum lipoprotein(a) levels. However, the Lp(a)-reducing potency of coffee diterpenes may subside in the long run, and their adverse side effects preclude their use as lipoprotein(a)-reducing agents. Sponsorship: Supported by the Netherlands Heart Foundation through grant No. 900-562-091 of the Netherlands Organization of Scientific Research (NWO), plus supplemental funding by the Institute for Scientific Information on Coffee
The Spectral Signature of Dust Scattering and Polarization in the Near IR to Far UV. I. Optical Depth and Geometry Effects
Spectropolarimetry from the near IR to the far UV of light scattered by dust
provides a valuable diagnostic of the dust composition, grain size distribution
and spatial distribution. To facilitate the use of this diagnostic, we present
detailed calculations of the intensity and polarization spectral signature of
light scattered by optically thin and optically thick dust in various
geometries. The polarized light radiative transfer calculations are carried out
using the adding-doubling method for a plane-parallel slab, and are extended to
an optically thick sphere by integrating over its surface. The calculations are
for the Mathis, Rumple & Nordsieck Galactic dust model, and cover the range
from 1 to 500 \AA. We find that the wavelength dependence of the
scattered light intensity provides a sensitive probe of the optical depth of
the scattering medium, while the polarization wavelength dependence provides a
probe of the grain scattering properties, which is practically independent of
optical depth. We provide a detailed set of predictions, including polarization
maps, which can be used to probe the properties of dust through imaging
spectropolarimetry in the near IR to far UV of various Galactic and
extragalactic objects. In a following paper we use the codes developed here to
provide predictions for the dependence of the intensity and polarization on
grain size distribution and composition.Comment: 29 pages + 21 figures, accepted for the Astrophysical Journal
Supplement February 2000 issue. Some revision, mostly in the introduction and
the conclusions, and a couple of correction
Electromagnetic Cascades and Cascade Nucleosynthesis in the Early Universe
We describe a calculation of electromagnetic cascading in radiation and
matter in the early universe initiated by the decay of massive particles or by
some other process. We have used a combination of Monte Carlo and numerical
techniques which enables us to use exact cross sections, where known, for all
the relevant processes. In cascades initiated after the epoch of big bang
nucleosynthesis -rays in the cascades will photodisintegrate He,
producing He and deuterium. Using the observed He and deuterium
abundances we are able to place constraints on the cascade energy deposition as
a function of cosmic time. In the case of the decay of massive primordial
particles, we place limits on the density of massive primordial particles as a
function of their mean decay time, and on the expected intensity of decay
neutrinos.Comment: compressed and uuencoded postscript. We now include a comparison with
previous work of the photon spectrum in the cascade and the limits we
calculate for the density of massive particles. The method of calculation of
photon spectra at low energies has been improved. Most figures are revised.
Our conclusions are substantially unchange
Characterizing exoplanetary atmospheres through infrared polarimetry
Planets can emit polarized thermal radiation, just like brown dwarfs. We
present calculated thermal polarization signals from hot exoplanets, using an
advanced radiative transfer code that fully includes all orders of scattering
by gaseous molecules and cloud particles. The code spatially resolves the disk
of the planet, allowing simulations for horizontally inhomogeneous planets. Our
results show that the degree of linear polarization, P, of an exoplanet's
thermal radiation is expected to be highest near the planet's limb and that
this P depends on the temperature and its gradient, the scattering properties
and the distribution of the cloud particles. Integrated over the disk of a
spherically symmetric planet, P of the thermal radiation equals zero. However,
for planets that appear spherically asymmetric, e.g. due to flattening, cloud
bands or spots in their atmosphere, differences in their day and night sides,
and/or obscuring rings, P is often larger than 0.1 %, in favorable cases even
reaching several percent at near-infrared wavelengths. Detection of thermal
polarization signals can give access to planetary parameters that are otherwise
hard to obtain: it immediately confirms the presence of clouds, and P can then
constrain atmospheric inhomogeneities and the flattening due to the planet's
rotation rate. For zonally symmetric planets, the angle of polarization will
yield the components of the planet's spin axis normal to the line-of-sight.
Finally, our simulations show that P is generally more sensitive to variability
in a cloudy planet's atmosphere than the thermal flux is, and could hence
better reveal certain dynamical processes.Comment: 9 pages, 5 figures, accepted for publication in Ap
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