192 research outputs found
early nutritional programming and progeny performance is reproductive success already set at birth
Compelling evidence indicates that the environment encountered dur-ing fetal life exerts a profound influence on development, physiological function, and risk of disease in adult mammals (Barker, 2007; Langley-Evans and McMullen, 2010). Development is a plastic process, wherein a range of different phenotypes can be expressed from a given genotype. The developing conceptuses respond to conditions in the environment during sensitive periods of cellular proliferation, differentiation, and maturation, resulting in structural and functional changes in cells, tissues, and organ systems. These changes may have short- and/or long-term consequences for health and disease susceptibility. Hence, the term "programming" has been adopted to describe the process whereby a stimulus or an insult at a critical and sensitive period of fetal or perinatal life has permanent effects on the structure, physiology, and metabolism of different organs and sys-tems. Despite many studies investigating the associations between mater-nal environment during fetal development and the onset of cardiovascular disease, obesity, and diabetes in offspring as adults (McMillen and Robin-son, 2005), few studies have investigated the impact of maternal environ-ment on the reproductive potential of offspring. This paper reviews the existing literature on the effects of prenatal and perinatal nutrition on the development and function of the reproductive system in female and male domestic mammals, with particular emphasis on cattle and sheep
Exponential Metric Fields
The Laser Interferometer Space Antenna (LISA) mission will use advanced
technologies to achieve its science goals: the direct detection of
gravitational waves, the observation of signals from compact (small and dense)
stars as they spiral into black holes, the study of the role of massive black
holes in galaxy evolution, the search for gravitational wave emission from the
early Universe. The gravitational red-shift, the advance of the perihelion of
Mercury, deflection of light and the time delay of radar signals are the
classical tests in the first order of General Relativity (GR). However, LISA
can possibly test Einstein's theories in the second order and perhaps, it will
show some particular feature of non-linearity of gravitational interaction. In
the present work we are seeking a method to construct theoretical templates
that limit in the first order the tensorial structure of some metric fields,
thus the non-linear terms are given by exponential functions of gravitational
strength. The Newtonian limit obtained here, in the first order, is equivalent
to GR.Comment: Accepted for publication in Astrophysics and Space Science, 17 page
Stable isotope profile (C, N, O, S) of Irish raw milk: Baseline data for authentication
Grass-based milk production is a major contributor to Irish agricultural output. The study characterized the Irish milk pool using stable isotope ratio analysis of carbon, nitrogen, oxygen and sulphur. Authentic raw milk samples were collected from 50 farms on five occasions over 13 months. Mean values of −27.11, 6.79, −3.27 and 6.16‰ were obtained for δ13C, δ15N, δ18O and δ34S, respectively. δ13C values reflected a high level of grass input and values increased with increasing cereal concentrate feed input (P < 0.001). δ18O values were most negative in spring. There was a significant interaction between feed and season for δ13C and δ15N values (P < 0.05), with the impact of concentrate feeding most evident in spring. δ34S values were lowest at the highest level of concentrate input (P < 0.05). The isotopic values reported here describe the Irish milk pool and may offer the potential to discriminate Irish milk and dairy products from similar commodities from other countries
Left vocal cord paralysis, lung function and exercise capacity in young adults born extremely preterm with a history of neonatal patent ductus arteriosus surgery—A national cohort study
Background: Left vocal cord paralysis (LVCP) is a known complication of patent ductus arteriosus (PDA) surgery in extremely preterm (EP) born neonates; however, consequences of LVCP beyond the first year of life are insufficiently described. Both voice problems and breathing difficulties during physical activity could be expected with an impaired laryngeal inlet. More knowledge may improve the follow-up of EP-born subjects who underwent PDA surgery and prevent confusion between LVCP and other diagnoses.
Objectives: Examine the prevalence of LVCP in a nationwide cohort of adults born EP with a history of PDA surgery, and compare symptoms, lung function, and exercise capacity between groups with and without LVCP, and vs. controls born EP and at term.
Methods: Adults born EP (<28 weeks' gestation or birth weight <1,000 g) in Norway during 1999–2000 who underwent neonatal PDA surgery and controls born EP and at term were invited to complete questionnaires mapping voice-and respiratory symptoms, and to perform spirometry and maximal treadmill exercise testing. In the PDA-surgery group, exercise tests were performed with a laryngoscope positioned to evaluate laryngeal function.
Results: Thirty out of 48 (63%) eligible PDA-surgery subjects were examined at mean (standard deviation) age 19.4 (0.8) years, sixteen (53%) had LVCP. LVCP was associated with self-reported voice symptoms and laryngeal obstruction during exercise, not with lung function or peak oxygen consumption (VO2peak). In the PDA-surgery group, forced expiratory volume in 1 second z-score (z-FEV1) was reduced compared to EP-born controls (n = 30) and term-born controls (n = 36); mean (95% confidence interval) z-FEV1 was −1.8 (−2.3, −1.2), −0.7 (−1.1, −0.3) and −0.3 (−0.5, −0.0), respectively. For VO2peak, corresponding figures were 37.5 (34.9, 40.2), 38.1 (35.1, 41.1), and 43.6 (41.0, 46.5) ml/kg/min, respectively.
Conclusions: LVCP was common in EP-born young adults who had undergone neonatal PDA surgery. Within the PDA-surgery group, LVCP was associated with self-reported voice symptoms and laryngeal obstruction during exercise, however we did not find an association with lung function or exercise capacity. Overall, the PDA-surgery group had reduced lung function compared to EP-born and term-born controls, whereas exercise capacity was similarly reduced for both the PDA-surgery and EP-born control groups when compared to term-born controls.publishedVersio
Non-monotonic variation with salt concentration of the second virial coefficient in protein solutions
The osmotic virial coefficient of globular protein solutions is
calculated as a function of added salt concentration at fixed pH by computer
simulations of the ``primitive model''. The salt and counter-ions as well as a
discrete charge pattern on the protein surface are explicitly incorporated. For
parameters roughly corresponding to lysozyme, we find that first
decreases with added salt concentration up to a threshold concentration, then
increases to a maximum, and then decreases again upon further raising the ionic
strength. Our studies demonstrate that the existence of a discrete charge
pattern on the protein surface profoundly influences the effective interactions
and that non-linear Poisson Boltzmann and Derjaguin-Landau-Verwey-Overbeek
(DLVO) theory fail for large ionic strength. The observed non-monotonicity of
is compared to experiments. Implications for protein crystallization are
discussed.Comment: 43 pages, including 17 figure
Leptonic and Semileptonic Decays of Charm and Bottom Hadrons
We review the experimental measurements and theoretical descriptions of
leptonic and semileptonic decays of particles containing a single heavy quark,
either charm or bottom. Measurements of bottom semileptonic decays are used to
determine the magnitudes of two fundamental parameters of the standard model,
the Cabibbo-Kobayashi-Maskawa matrix elements and . These
parameters are connected with the physics of quark flavor and mass, and they
have important implications for the breakdown of CP symmetry. To extract
precise values of and from measurements, however,
requires a good understanding of the decay dynamics. Measurements of both charm
and bottom decay distributions provide information on the interactions
governing these processes. The underlying weak transition in each case is
relatively simple, but the strong interactions that bind the quarks into
hadrons introduce complications. We also discuss new theoretical approaches,
especially heavy-quark effective theory and lattice QCD, which are providing
insights and predictions now being tested by experiment. An international
effort at many laboratories will rapidly advance knowledge of this physics
during the next decade.Comment: This review article will be published in Reviews of Modern Physics in
the fall, 1995. This file contains only the abstract and the table of
contents. The full 168-page document including 47 figures is available at
http://charm.physics.ucsb.edu/papers/slrevtex.p
Measurement of the Decay Asymmetry Parameters in and
We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\
decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for
the decay mode and \aLC = -0.45\pm 0.31 \pm
0.06 for the decay mode . By combining these
measurements with the previously measured decay rates, we have extracted the
parity-violating and parity-conserving amplitudes. These amplitudes are used to
test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures
as uuencoded postscript. Also available as
http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p
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The effect of asymmetries on stock index return value-at-risk estimates
It is widely accepted that equity return volatility increases more following negative shocks rather than positive shocks. However, much of value-at-risk (VaR) analysis relies on the assumption that returns are normally distributed (a symmetric distribution). This article considers the effect of asymmetries on the evaluation and accuracy of VaR by comparing estimates based on various models
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