632 research outputs found
The distribution and chromatographic characterization of PHI (peptide histidine isoleucine amide)-27-like peptides in rat and porcine brain
[No abstract available
Hard-Sphere Fluids in Contact with Curved Substrates
The properties of a hard-sphere fluid in contact with hard spherical and
cylindrical walls are studied. Rosenfeld's density functional theory (DFT) is
applied to determine the density profile and surface tension for wide
ranges of radii of the curved walls and densities of the hard-sphere fluid.
Particular attention is paid to investigate the curvature dependence and the
possible existence of a contribution to that is proportional to the
logarithm of the radius of curvature. Moreover, by treating the curved wall as
a second component at infinite dilution we provide an analytical expression for
the surface tension of a hard-sphere fluid close to arbitrary hard convex
walls. The agreement between the analytical expression and DFT is good. Our
results show no signs for the existence of a logarithmic term in the curvature
dependence of .Comment: 15 pages, 6 figure
Evidence for phase formation in potassium intercalated 1,2;8,9-dibenzopentacene
We have prepared potassium intercalated 1,2;8,9-dibenzopentacene films under
vacuum conditions. The evolution of the electronic excitation spectra upon
potassium addition as measured using electron energy-loss spectroscopy clearly
indicate the formation of particular doped phases with compositions
Kdibenzopentacene ( = 1,2,3). Moreover, the stability of these phases as
a function of temperature has been explored. Finally, the electronic excitation
spectra also give insight into the electronic ground state of the potassium
doped 1,2;8,9-dibenzopentacene films.Comment: 6 pages, 5 figures. arXiv admin note: text overlap with
arXiv:1201.200
Implementing NICE guidelines for the psychological treatment of depression and anxiety disorders: The IAPT experience
The Improving Access to Psychological Therapies (IAPT) programme is a large-scale initiative that aims to greatly increase the availability of NICE recommended psychological treatment for depression and anxiety disorders within the National Health Service in England. This article describes the background to the programme, the arguments on which it is based, the therapist training scheme, the clinical service model, and a summary of progress to date. At mid-point in a national roll-out of the programme progress is generally in line with expectation, and a large number of people who would not otherwise have had the opportunity to receive evidence-based psychological treatment have accessed, and benefited from, the new IAPT services. Planned future developments and challenges for the programme are briefly described
Superconductivity in the two dimensional Hubbard Model.
Quasiparticle bands of the two-dimensional Hubbard model are calculated using
the Roth two-pole approximation to the one particle Green's function. Excellent
agreement is obtained with recent Monte Carlo calculations, including an
anomalous volume of the Fermi surface near half-filling, which can possibly be
explained in terms of a breakdown of Fermi liquid theory. The calculated bands
are very flat around the (pi,0) points of the Brillouin zone in agreement with
photoemission measurements of cuprate superconductors. With doping there is a
shift in spectral weight from the upper band to the lower band. The Roth method
is extended to deal with superconductivity within a four-pole approximation
allowing electron-hole mixing. It is shown that triplet p-wave pairing never
occurs. Singlet d_{x^2-y^2}-wave pairing is strongly favoured and optimal
doping occurs when the van Hove singularity, corresponding to the flat band
part, lies at the Fermi level. Nearest neighbour antiferromagnetic correlations
play an important role in flattening the bands near the Fermi level and in
favouring superconductivity. However the mechanism for superconductivity is a
local one, in contrast to spin fluctuation exchange models. For reasonable
values of the hopping parameter the transition temperature T_c is in the range
10-100K. The optimum doping delta_c lies between 0.14 and 0.25, depending on
the ratio U/t. The gap equation has a BCS-like form and (2*Delta_{max})/(kT_c)
~ 4.Comment: REVTeX, 35 pages, including 19 PostScript figures numbered 1a to 11.
Uses epsf.sty (included). Everything in uuencoded gz-compressed .tar file,
(self-unpacking, see header). Submitted to Phys. Rev. B (24-2-95
Erratum: Evidence for a model of agonist-induced activation of 5-hydroxytryptamine 2A serotonin receptors that involves the disruption of a strong ionic interaction between helices 3 and 6 (Journal of Biological Chemistry (2002) 277 (11441-11449))
[No abstract available
Evidence for a model of agonist-induced activation of 5-hydroxytryptamine 2A serotonin receptors that involves the disruption of a strong ionic interaction between helices 3 and 6
5-Hydroxytryptamine 2A (5-HT2A) receptors are essential for the actions of serotonin (5-hydroxytryptamine (5-HT)) on physiological processes as diverse as vascular smooth muscle contraction, platelet aggregation, perception, and emotion. In this study, we investigated the molecular mechanism(s) by which 5-HT activates 5-HT2A receptors using a combination of approaches including site-directed mutagenesis, molecular modeling, and pharmacological analysis using the sensitive, cell-based functional assay R-SAT. Alanine-scanning mutagenesis of residues close to the intracellular end of H6 of the 5-HT2A receptor implicated glutamate Glu-318(6.30) in receptor activation, as also predicted by a newly constructed molecular model of the 5-HT2A receptor, which was based on the x-ray structure of bovine rhodopsin. Close examination of the molecular model suggested that Glu-318(6.30) could form a strong ionic interaction with Arg-173(3.50) of the highly conserved "(D/E)RY motif" located at the interface between the third transmembrane segment and the second intracellular loop (i2). A direct prediction of this hypothesis, that disrupting this ionic interaction by an E318(6.30)R mutation would lead to a highly constitutively active receptor with enhanced affinity for agonist, was confirmed using R-SAT. Taken together, these results predict that the disruption of a strong ionic interaction between transmembrane helices 3 and 6 of 5-HT2A receptors is essential for agonist-induced receptor activation and, as recently predicted by ourselves (B. L. Roth and D. A. Shapiro (2001) Expert Opin. Ther. Targets 5, 685-695) and others, that this may represent a general mechanism of activation for many, but not all, G-protein-coupled receptors
Photoemission spectra of : a theoretical analysis
Recent angle resolved photoemission (ARPES) results for the insulating
cuprate have provided the first experimental data
which can be directly compared to the (theoretically) well--studied problem of
a single hole propagating in an antiferromagnet. The ARPES results reported a
small bandwidth, providing evidence for the existence of strong correlations in
the cuprates. However, in the same experiment some discrepancies with the
familiar 2D model were also observed. Here we discuss a comparison
between the ARPES results and the quasiparticle dispersion of both (i) the
Hamiltonian and (ii) the three--band Hubbard model in the
strong--coupling limit. Both model Hamiltonians show that the experimentally
observed one--hole band structure can be approximately reproduced using
reasonable values for , or the direct oxygen hopping amplitude .Comment: 11 pages, RevTex version 3.0, 3 postscript figures, LaTeX file and
figures have been uuencoded
Insulator-Superfluid transition of spin-1 bosons in an optical lattice in magnetic field
We study the insulator-superfluid transition of spin-1 bosons in an optical
lattice in a uniform magnetic field. Based on a mean-field approximation we
obtained a zero-temperature phase diagram. We found that depending on the
particle number the transition for bosons with antiferromagnetic interaction
may occur into different superfluid phases with spins aligned along or opposite
to the field direction. This is qualitatively different from the field-free
transition for which the mean-field theory predicts a unique (polar) superfluid
state for any particle number.Comment: 10 pages, 2 eps figure
Electronic and Structural Properties of a 4d-Perovskite: Cubic Phase of SrZrO
First-principles density functional calculations are performed within the
local density approximation to study the electronic properties of SrZrO, an
insulating 4d-perovskite, in its high-temperature cubic phase, above 1400 K, as
well as the generic 3d-perovskite SrTiO, which is also a d^0-insulator and
cubic above 105 K, for comparison reasons. The energy bands, density of states
and charge density distributions are obtained and a detailed comparison between
their band structures is presented. The results are discussed also in terms of
the existing data in the literature for both oxides.Comment: 5 pages, 2 figure
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