1,723 research outputs found
Decreased numerical density of kainate receptor-positive neurons in the orbitofrontal cortex of chronic schizophrenics
We utilised postmortem brain tissue to quantify sections of left and right orbitofrontal cortex (area 11) from nine schizophrenic and eight control patients from the Charing Cross Prospective Schizophrenia Study immunostained for the presence of the kainate receptor (GluR5/6/7). The numerical density of neurons immunopositive for kainate receptor was measured. Other sections from the same blocks were stained with cresyl violet to determine the total neuronal numerical density. All measurements were made blind: diagnoses were only revealed by a third party after measurements were completed. There was a significant reduction (21%) in numerical density of kainate receptor-positive neurons in both cortices in the schizophrenic group (488cells/mm2) compared to that in the control group (618cells/mm2) (P=0.033). Nissl-stained tissue showed no significant difference in total neuronal numerical density between control and schizophrenic groups. These observations suggest that there are actually fewer kainate receptor-positive neurons in schizophrenic orbitofrontal cortex. There was no correlation of reduced kainate receptor-positive cell number with age at death, postmortem interval, or other possibly confounding neuropathology. Our results support the concept of there being reduced glutamatergic activity in frontal cortex in schizophreni
Switching of Geometric Phase in Degenerate Systems
The geometric and open path phases of a four-state system subject to time
varying cyclic potentials are computed from the Schr\"{o}dinger equation. Fast
oscillations are found in the non-adiabatic case. For parameter values such
that the system possesses degenerate levels, the geometric phase becomes
anomalous, undergoing a sign switch. A physical system to which the results
apply is a molecular dimer with two interacting electrons. Additionally, the
sudden switching of the geometric phase promises to be an efficient control in
two-qubit quantum computing.Comment: 15 pages, 4 figures,accepted by Physics Letters A (2000
Pair Fluctuations in Ultra-small Fermi Systems within Self-Consistent RPA at Finite Temperature
A self-consistent version of the Thermal Random Phase Approximation (TSCRPA)
is developed within the Matsubara Green's Function (GF) formalism. The TSCRPA
is applied to the many level pairing model. The normal phase of the system is
considered. The TSCRPA results are compared with the exact ones calculated for
the Grand Canonical Ensemble. Advantages of the TSCRPA over the Thermal Mean
Field Approximation (TMFA) and the standard Thermal Random Phase Approximation
(TRPA) are demonstrated. Results for correlation functions, excitation
energies, single particle level densities, etc., as a function of temperature
are presented.Comment: 22 pages, 13 figers and 3 table
Legal coercion, respect & reason-responsive agency
Legal coercion seems morally problematic because it is susceptible to the Hegelian objection that it fails to respect individuals in a way that is ‘due to them as men’. But in what sense does legal coercion fail to do so? And what are the grounds for this requirement to respect? This paper is an attempt to answer these questions. It argues that (a) legal coercion fails to respect individuals as reason-responsive agents; and (b) individuals ought to be respected as such in virtue of the fact that they are human beings. Thus it is in this sense that legal coercion fails to treat individuals with the kind of respect ‘due to them as men’.The Leverhulme Trust (ECF-2012-032); AHRC (AH/H015655/1
Magnetism and Pairing in Hubbard Bilayers.
We study the Hubbard model on a bilayer with repulsive on-site interactions,
, in which fermions undergo both intra-plane () and inter-plane ()
hopping. This situation is what one would expect in high-temperature
superconductors such as YBCO, with two adjacent CuO planes. Magnetic and
pairing properties of the system are investigated through Quantum Monte Carlo
simulations for both half- and quarter-filled bands. We find that in all cases
inter-planar pairing with symmetry is dominant over planar
pairing with symmetry, and that for large enough pair
formation is possible through antiferromagnetic correlations. However, another
mechanism is needed to make these pairs condense into a superconducting state
at lower temperatures. We identify the temperature for pair formation with the
spin gap crossover temperature. [Submitted to Phys. Rev. B]Comment: 7 pages, uuencoded self-unpacking PS file with text and figures
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