2,613 research outputs found
Identification of muscle and adipose gene expression patterns in lean and obese pigs
Obesity is a major risk factor of preventable deaths worldwide, with increasing rates being observed in adults and children. To understand the mechanisms of obesity development, genetically lean (Duroc strain) and obese (Rongchang strain) pigs were used to identify potential differences in muscle and adipose development patterns following consumption of an identical diet for 180 days. Lean pigs had a significantly higher lean percentage (67.79% versus 44.71%) and lower obesity index (0.68 versus 0.84) than obese pigs. They also exhibited significantly lower adipocyte volumes and higher myofibre cross-sectional areas. Quantitative polymerase chain reaction showed that lean pigs had a significantly higher expression of muscle growth-related genes and lower expression of lipogenesis-related genes. By contrast, obese pigs had higher expression of a myostatin-related gene and lower expression of lipolysis-related genes. Additionally, the mitochondrial DNA copy number was higher in the muscle and lower in adipose tissue in lean compared with obese pigs. These results indicate that lean pigs have a distinct development pattern from obese pigs, involving lipogenesis, muscle growth, and energy metabolism. This study provides a basis for exploring the mechanisms of adipose deposition and muscle growth in obesity.Keywords: Obesity, mitochondrial DNA, Sus scrof
Spin polaron damping in the spin-fermion model for cuprate superconductors
A self-consistent, spin rotational invariant Green's function procedure has
been developed to calculate the spectral function of carrier excitations in the
spin-fermion model for the CuO2 plane. We start from the mean field description
of a spin polaron in the Mori-Zwanzig projection method. In order to determine
the spin polaron lifetime in the self-consistent Born approximation, the
self-energy is expressed by an irreducible Green's function. Both, spin polaron
and bare hole spectral functions are calculated. The numerical results show a
well pronounced quasiparticle peak near the bottom of the dispersion at
(pi/2,pi/2), the absence of the quasiparticle at the Gamma-point, a rather
large damping away from the minimum and an asymmetry of the spectral function
with respect to the antiferromagnetic Brillouin zone. These findings are in
qualitative agreement with photoemission data for undoped cuprates. The direct
oxygen-oxygen hopping is responsible for a more isotropic minimum at
(pi/2,pi/2).Comment: 18 pages, 13 figure
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Epigenetic Interactions and the Structure of Phenotypic Variation in the Cranium
Understanding the developmental and genetic
basis for evolutionarily significant morphological variation in
complex phenotypes such as themammalian skull is a challenge
because of the sheer complexity of the factors involved. We
hypothesize that even in this complex system, the expression of
phenotypic variation is structured by the interaction of a few key
developmental processes. To test this hypothesis, we created a
highly variable sample of crania using four mouse mutants and
their wild-type controls from similar genetic backgrounds with
developmental perturbations to particular cranial regions. Using
geometricmorphometricmethods we compared patterns of size,
shape, and integration in the sample within and between the
basicranium, neurocranium, and face. The results highlight
regular and predictable patterns of covariation among regions of
the skull that presumably reflect the epigenetic influences of the
genetic perturbations in the sample. Covariation between
relative widths of adjoining regions is the most dominant factor,
but there are other significant axes of covariation such as the
relationship between neurocranial size and basicranial flexion.
Although there are other sources of variation related to
developmental perturbations not analyzed in this study, the
patterns of covariation created by the epigenetic interactions
evident in this sample may underlie larger scale evolutionary
patterns in mammalian craniofacial form.Anthropolog
Influence of oxygen on chemoconvective patterns in the iodine clock reaction
There is increasing interest in using chemical clock reactions to drive material formation; however, these reactions are often subject to chemoconvective effects, and control of such systems remains challenging. Here, we show how the transfer of oxygen at the airâwater interface plays a crucial role in the spatiotemporal behavior of the iodine clock reaction with sulfite. A kinetic model was developed to demonstrate how the reaction of oxygen with sulfite can control a switch from a low-iodine to high-iodine state under well-stirred conditions and drive the formation of transient iodine gradients in unstirred solutions. In experiments in thin layers with optimal depths, the reaction couples with convective instability at the airâwater interface forming an extended network-like structure of iodine at the surface that develops into a spotted pattern at the base of the layer. Thus, oxygen drives the spatial separation of iodine states essential for patterns in this system and may influence pattern selection in other clock reaction systems with sulfite
Nitrogen enrichment lowers Betula pendula green and yellow leaf stoichiometry irrespective of effects of elevated carbon dioxide.
Elevated carbon dioxide (C
Attitudes to a male contraceptive pill in a group of contraceptive users in the UK
BACKGROUND. Small scale trials of male hormonal contraception have produced encouraging results. Attitudes to and beliefs about a proposed male pill may affect uptake. METHODS. This paper examines attitudes towards a proposed âmale contraceptive pillâ among a self selected sample of 54 men and 134 women, living in a non-metropolitan centre in the East of England, United Kingdom who were already users of contraception. Thirty four respondents were also interviewed and their views on the male pill were qualitatively analysed.
RESULTS. The acceptability of a male pill was high with just under half (49.5%) of respondents indicating that they would use it. Gender, length of relationship, age and educational achievement did not affect the reported acceptability. 42% of respondents expressed concerns that men would forget to take a male pill. Women were significantly more likely to express this concern than men. 26% of respondents expressed health concerns. Willingness to take a male pill was associated with expressing the view that increased protection against pregnancy would be an advantage of such a method. Those unwilling or undecided were more likely to express concerns about the effect of a pill on future fertility.
CONCLUSIONS. A male pill was accepted as a potential aid to increased fertility control by a large proportion of a convenience sample of contraceptive users in the East of England. If a male pill were to be marketed in the UK this study suggests that concerns about effects on future fertility and health risks may need to be addressed
Stability of an Exciton bound to an Ionized Donor in Quantum Dots
Total energy, binding energy, recombination rate (of the electron hole pair)
for an exciton (X) bound in a parabolic two dimensional quantum dot by a donor
impurity located on the z axis at a distance d from the dot plane, are
calculated by using the Hartree formalism with a recently developed numerical
method (PMM) for the solution of the Schroedinger equation. As our analysis
indicates there is a critical dot radius such that for radius less than the
critical radius the complex is unstable and with an increase of the impurity
distance this critical radius increases. Furthermore, there is a critical value
of the mass ratio such that for mass ratio less than the critical value the
complex is stable. The appearance of this stability condition depends both on
the impurity distance and the dot radius, in a way that with an increase of the
impurity distance we have an increase in the maximum dot radius where this
stability condition appears. For dot radii greater than this maximum dot radius
(for fixed impurity distance) the complex is always stable.Comment: 17 pages, 7 figures Applying a new numerical method which is based on
the adiabatic stability of quantum mechanics, we study the stability of an
exciton (X) bound in a parabolic two dimensional quantum dot by a donor
impurity located on the z axis at a distance d from the dot plan
Analytical characterization of damping in gear teeth dynamics under hydrodynamic conditions
Using an analytical method, we characterize damping and stiffness in lightly loaded, lubricated gear pairs at different operating speeds and lubricant temperatures. This is accomplished by employing a trace method to approximate and model the hysteresis loop of the lubricant reaction, thus recording the energy transformation mechanism during the gear teeth oscillatory motion. The method can be expanded for use in a variety of problems where hydrodynamic vibro-impacts lead to energy dissipation
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