323 research outputs found
The Effect of a Reduced-Calorie Diet on alpha-2 Adrenergic Receptor Responsiveness in Abdominal Adipose Tissue in Obese Men During Exercise
There is at present an imperfect understanding of the effect of diet on availability of inhibitory receptors in fat cells during exercise among obese men. 

*Objective:* The purpose of this study was to determine whether diet results in downregulation of alpha-2 adrenergic receptor ([alpha]~2-AR~) messenger RNA (mRNA), improving metabolism in exercise in obese men. 

*Design:* One group, pre-test, post-test design.

*Measurements:* Subcutaneous abdominal adipose tissue was tested for physiologic response, such as changes in catecholamines and other markers of lipolysis measured during periods of exercise, before and after a 12-week diet. Plasma markers of lipolysis/antilipolytic activity (catecholamines [adrenaline and noradrenaline], NEFA, lactate, glucose, hematocrit, or insulin levels) were analyzed at four points in time in order to determine the effect of exercise on [alpha]~2-AR~ and [beta]-AR responsiveness to sympathetic stimulation.

*Subjects:* Otherwise healthy 18 to 45 year old obese men (defined as a body mass index (BMI) over 33 kg/m^2^).

*Results:* The 12-week reduced calorie diet did not result in improved metabolism. Instead, upregulation of alpha-2 adrenergic receptor ([alpha]~2-AR~) messenger RNA (mRNA) was observed. On average, [alpha]~2-AR~ mRNA levels (ratio of [alpha]~2-AR~ to cyclophilin) in subjects increased by 0.022-0.023 after the diet. The average differences in of [alpha]~2-AR~ mRNA and [beta]-AR mRNA measured before and after diet were both insignificant (M = 0.015) t(4) = -0.911; _P_ > 0.05; (M = 0.0139; t(4) = 0.077; _P_ > 0.05). 

*Conclusion:* The observed direction of change in [alpha]~2-AR~ mRNA levels, when viewed together with the stability of [beta]-AR mRNA levels, suggests that upregulation of [alpha]~2-AR~ rather than downregulation occurred. Downregulation would account for decreased lipolytic activity during exercise, future study is needed
Low abundances of heavy elements in the solar outer layers: comparisons of solar models with helioseismic inversions
Recent solar photospheric abundance analyses have led to a significant
reduction of the metal abundances compared to the previous determinations. The
solar models computed with standard opacities and diffusion processes using
these new abundances give poor agreement with helioseismic inversions for the
sound-speed profile, the surface helium abundance, and the convective zone
depth.
We attempt to obtain a good agreement between helioseismic inversions and
solar models which present the "old" mixture in the interior and new chemical
composition in the convective zone. To reach this result, we assume an
undermetallic accretion at the beginning of the main sequence.
We compute solar models with the Toulouse-Geneva Evolution Code, in which we
simulate an undermetallic accretion in the early stages of the main sequence,
in order to obtain new mixture in the outer convective zone. We compare the
sound-speed profile, the convective zone depth, and the surface helium
abundance with those deduced from helioseismology.
The model with accretion but without any mixing process inside is in better
agreement with helioseismology than the solar model with the new abundances
throughout. There is, however, a spike under the convective zone which reaches
3.4%. Furthermore, the convective zone depth and the surface helium abundance
are too low. Introducing undershooting below the convective zone allows us to
recover the good convective zone radius and the addition of rotation-induced
mixing and tachocline allows us to reconcile the surface helium abundance. But
in any case the agreement of the sound-speed profile with helioseismic
inference is worse than obtained with the old abundances.Comment: 5 pages, 2 figure
Numerical analysis of a folded superconducting coaxial shield for cryogenic current comparators
This paper presents a new shield configuration for cryogenic current
comparators (CCCs), namely the folded coaxial geometry. An analytical model
describing its shielding performance is first developed, and then validated by
means of finite element simulations. Thanks to this model, the fundamental
properties of the new shield are highlighted. Additionally, this paper compares
the volumetric performance of the folded coaxial shield to the one of a ring
shield, the latter being installed in many CCCs for measuring particle beam
currents in accelerator facilities.Comment: 13 pages, 15 figure
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
Neutron Scattering study of Sr_2Cu_3O_4Cl_2
We report a neutron scattering study on the tetragonal compound
Sr_2Cu_3O_4Cl_2, which has two-dimensional (2D) interpenetrating Cu_I and
Cu_{II} subsystems, each forming a S=1/2 square lattice quantum Heisenberg
antiferromagnet (SLQHA). The mean-field ground state is degenerate, since the
inter-subsystem interactions are geometrically frustrated. Magnetic neutron
scattering experiments show that quantum fluctuations lift the degeneracy and
cause a 2D Ising ordering of the Cu_{II} subsystem. Due to quantum fluctuations
a dramatic increase of the Cu_I out-of-plane spin-wave gap is also observed.
The temperature dependence and the dispersion of the spin-wave energy are
quantitatively explained by spin-wave calculations which include quantum
fluctuations explicitly. The values for the nearest-neighbor superexchange
interactions between the Cu_I and Cu_{II} ions and between the Cu_{II} ions are
determined experimentally to be J_{I-II} = -10(2)meV and J_{II}= 10.5(5)meV,
respectively. Due to its small exchange interaction, J_{II}, the 2D dispersion
of the Cu_{II} SLQHA can be measured over the whole Brillouin zone with thermal
neutrons, and a novel dispersion at the zone boundary, predicted by theory, is
confirmed. The instantaneous magnetic correlation length of the Cu_{II} SLQHA
is obtained up to a very high temperature, T/J_{II}\approx 0.75. This result is
compared with several theoretical predictions as well as recent experiments on
the S=1/2 SLQHA.Comment: Figures and equations are rearrange
Histamine-induced itch and its relationship with pain
Itch is one of the major complications of skin diseases. Although there are various substances that induce itch or pruritus, it is evident that histamine is the best known endogenous agent that evokes itch. Even though histamine-induced itch has been studied for some time, the underlying mechanism of itch is just beginning to emerge. Although various downstream signaling pathways of histamine receptors have been revealed, more studies are required to determine the cause of histamine-induced itch. It appears that itch and pain involve different neuronal pathways. Pain generally inhibits itch, which indicates an inter-communication between the two. Complex interactions between itch and pain may be expected based on reports on disease states and opioids. In this review, we discuss the molecular mechanism and the pharmacological aspects of histamine-induced itch. Especially, the underlying mechanism of TRPV1 (an anti-pruritus target) has been determined to some extent
Vascular responses of the extremities to transdermal application of vasoactive agents in Caucasian and African descent individuals
This is an accepted manuscript of an article published by Springer in European Journal of Applied Physiology on 04/04/2015, available online: https://doi.org/10.1007/s00421-015-3164-2
The accepted version of the publication may differ from the final published version.© 2015, Springer-Verlag Berlin Heidelberg. Purpose: Individuals of African descent (AFD) are more susceptible to non-freezing cold injury than Caucasians (CAU) which may be due, in part, to differences in the control of skin blood flow. We investigated the skin blood flow responses to transdermal application of vasoactive agents. Methods: Twenty-four young males (12 CAU and 12 AFD) undertook three tests in which iontophoresis was used to apply acetylcholine (ACh 1 w/v %), sodium nitroprusside (SNP 0.01 w/v %) and noradrenaline (NA 0.5 mM) to the skin. The skin sites tested were: volar forearm, non-glabrous finger and toe, and glabrous finger (pad) and toe (pad). Results: In response to SNP on the forearm, AFD had less vasodilatation for a given current application than CAU (P = 0.027–0.004). ACh evoked less vasodilatation in AFD for a given application current in the non-glabrous finger and toe compared with CAU (P = 0.043–0.014) with a lower maximum vasodilatation in the non-glabrous finger (median [interquartile], AFD n = 11, 41[234] %, CAU n = 12, 351[451] %, P = 0.011) and non-glabrous toe (median [interquartile], AFD n = 9, 116[318] %, CAU n = 12, 484[720] %, P = 0.018). ACh and SNP did not elicit vasodilatation in the glabrous skin sites of either group. There were no ethnic differences in response to NA. Conclusion: AFD have an attenuated endothelium-dependent vasodilatation in non-glabrous sites of the fingers and toes compared with CAU. This may contribute to lower skin temperature following cold exposure and the increased risk of cold injuries experienced by AFD.Published versio
On Solving the Coronal Heating Problem
This article assesses the current state of understanding of coronal heating,
outlines the key elements of a comprehensive strategy for solving the problem,
and warns of obstacles that must be overcome along the way.Comment: Accepted by Solar Physics; Published by Solar Physic
Earthworm functioning in soil ecosystem services in relation to land use intensity
The FP7 EcoFINDERS project aimed to assess the relationship
between soil biodiversity and ecosystem service provision. We
studied functional responses for earthworms and fungi on soil
formation and water regulation under different agricultural land
uses representing a range in land use intensity. The aim was to
establish and quantify these functional relationships by literature
and field studies
Enchytraeids in two phytophysiognomies of Brazilian Cerrado.
This is the first study on enchytraeid diversity in phytophysiognomies of the Brazilian Cerrado Biome carried out with standard sampling and extraction methods. Shrubby woodland (Cerrado sensu stricto, CSR) and gallery forest (MG) was sampled in the Brasilia Botanical Garden Ecological Station and the Brasilia National Park, respectively, with samplings performed at the end of the rainy season in 2017 and 2018. Enchytraeid population density in MG was higher than in CSR, reaching more than 30 thousand individuals/ m2 in MG and 5 thousand in CSR. Enchytraeid abundance was influenced by soil organic matter and moisture. So far, six genera and six potentially new species taxa were identified. Dominant genera were Guaranidrilus and Hemienchytraeus
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