1,564 research outputs found
A comparison of the immunoglobulins, IgA, IgG and IgE in nasal secretions from normal and asthmatic children
The secreted proteins obtained from nasal washings from eighty-five normal children and fifty asthmatic children, between 6 and 14 years, were investigated by immunological assay for their content of albumin, secretory IgA and IgG. A smaller number of specimens from asthmatic and normal children were examined for their IgE content. There was no statistically significant difference in the levels of albumin, secretory IgA and IgG in the asthmatic and the normal children. The IgE content of nasal wash protein in normal children averaged approximately 70 ng/mg of protein, whereas the IgE content in the asthmatic children averaged greater than 400 ng/mg of wash protein
The role of epigenetics in cardiovascular health and ageing: A focus on physical activity and nutrition
The cardiovascular system is responsible for transport of blood and nutrients to tissues, and is pivotal to the physiological health and longevity. Epigenetic modification is a natural, age-associated process resulting in highly contextualised gene expression with clear implications for cell differentiation and disease onset. Biological/epigenetic age is independent of chronological age, constituting a highly reflective snapshot of an individual\u27s overall health. Accelerated vascular ageing is of major concern, effectively lowering disease threshold. Age-related chronic illness involves a complex interplay between many biological processes and is modulated by non-modifiable and modifiable risk factors. These alter the static genome by a number of epigenetic mechanisms, which change gene expression in an age and lifestyle dependent manner. This \u27epigenetic drift\u27 impacts health and contributes to the etiology of chronic illness. Lifestyle factors may cause acceleration of this epigenetic "clock", pre-disposing individuals to cardiovascular disease. Nutrition and physical activity are modifiable lifestyle choices, synergistically contributing to cardiovascular health. They represent a powerful potential epigenetic intervention point for effective cardiovascular protective and management strategies. Thus, together with traditional risk factors, monitoring the epigenetic signature of ageing may prove beneficial for tailoring lifestyle to fit biology - supporting the increasingly popular concept of "ageing well"
Use of airborne laser scanning to assess effects of understorey vegetation structure on nest-site selection and breeding performance in an Australian passerine bird
A model of the Universe including Dark Energy accounted for by both a Quintessence Field and a (negative) Cosmological Constant
In this work we present a model of the universe in which dark energy is
modelled explicitely with both a dynamical quintessence field and a
cosmological constant. Our results confirm the possibility of a future
collapsing universe (for a given region of the parameter space), which is
necessary for a consistent formulation of string theory and quantum field
theory. We have also reproduced the measurements of modulus distance from
supernovae with good accuracy.Comment: 11 pages, 4 figures, only the results for the single exponential
potential are preserved. One author added. Some changes in the reference
section. Submitted to Physical Review
Cosmological Tracking Solutions
A substantial fraction of the energy density of the universe may consist of
quintessence in the form of a slowly-rolling scalar field. Since the energy
density of the scalar field generally decreases more slowly than the matter
energy density, it appears that the ratio of the two densities must be set to a
special, infinitesimal value in the early universe in order to have the two
densities nearly coincide today.
Recently, we introduced the notion of tracker fields to avoid this initial
conditions problem. In the paper, we address the following questions: What is
the general condition to have tracker fields? What is the relation between the
matter energy density and the equation-of-state of the universe imposed by
tracker solutions? And, can tracker solutions explain why quintessence is
becoming important today rather than during the early universe
Effect of logic family on radiated emissions from digital circuits
Radiated emissions were measured for simple digital circuits designed to operate with various logic families. Emissions in the near and far field were found to depend both on the circuit layout and the choice of logic family. However, the difference in peak emissions between any two logic families was found to be independent of circuit layout. The greatest difference in peak emissions was between high-speed 74ACT logic and low-speed 4000 CMOS logic devices, with a mean value of approximately 20 dB. Emissions from a more complex circuit were compared with the measurements on simple loop circuits. Test circuits were used to measure the propagation delay, the rise and fall times, the maximum operating frequency and the transient switching currents between two successive logic gates for each logic family. Empirical formulas have been derived that relate relative peak emissions to these switching parameters. It is hoped that these will assist designers to assess the effect of choice of logic family on electromagnetic compatibility
Magnetic fields in the early universe in the string approach to MHD
There is a reformulation of magnetohydrodynamics in which the fundamental
dynamical quantities are the positions and velocities of the lines of magnetic
flux in the plasma, which turn out to obey equations of motion very much like
ideal strings. We use this approach to study the evolution of a primordial
magnetic field generated during the radiation-dominated era in the early
Universe. Causality dictates that the field lines form a tangled random
network, and the string-like equations of motion, plus the assumption of
perfect reconnection, inevitably lead to a self-similar solution for the
magnetic field power spectrum. We present the predicted form of the power
spectrum, and discuss insights gained from the string approximation, in
particular the implications for the existence or not of an inverse cascade.Comment: 12 pages, 2 figure
CBR Anisotropy from Primordial Gravitational Waves in Two-Component Inflationary Cosmology
We examine stochastic temperature fluctuations of the cosmic background
radiation (CBR) arising via the Sachs-Wolfe effect from gravitational wave
perturbations produced in the early universe. We consider spatially flat,
perturbed FRW models that begin with an inflationary phase, followed by a mixed
phase containing both radiation and dust. The scale factor during the mixed
phase takes the form , where are
constants. During the mixed phase the universe smoothly transforms from being
radiation to dust dominated. We find analytic expressions for the graviton mode
function during the mixed phase in terms of spheroidal wave functions. This
mode function is used to find an analytic expression for the multipole moments
of the two-point angular correlation function
for the CBR anisotropy. The analytic expression for the multipole
moments is written in terms of two integrals, which are evaluated numerically.
The results are compared to multipoles calculated for models that are {\it
completely} dust dominated at last-scattering. We find that the multipoles
of the CBR temperature perturbations for are
significantly larger for a universe that contains both radiation and dust at
last-scattering. We compare our results with recent, similar numerical work and
find good agreement. The spheroidal wave functions may have applications to
other problems of cosmological interest.Comment: 28 pgs + 6 postscript figures, RevTe
- …