1,486 research outputs found
Canonical Quantization and Expanding Metrics
The canonical formalism for expanding metrics scenarios is presented.
Non-unitary time evolution implied by expanding geometry is described as a
trajectory over unitarily inequivalent representations at different times of
the canonical commutation relations. Thermal properties of inflating Universe
are also discussed.Comment: 10 pages, 2 figure
The dissipative quantum model of brain: how do memory localize in correlated neuronal domains
The mechanism of memory localization in extended domains is described in the
framework of the parametric dissipative quantum model of brain. The size of the
domains and the capability in memorizing depend on the number of links the
system is able to establish with the external world.Comment: 19 PostScript pages, in press on a special issue of Information
Science Journal, S. Kak and D. Ventura Ed
Formation and life-time of memory domains in the dissipative quantum model of brain
We show that in the dissipative quantum model of brain the time-dependence of
the frequencies of the electrical dipole wave quanta leads to the dynamical
organization of the memories in space (i.e. to their localization in more or
less diffused regions of the brain) and in time (i.e. to their longer or
shorter life-time). The life-time and the localization in domains of the memory
states also depend on internal parameters and on the number of links that the
brain establishes with the external world. These results agree with the
physiological observations of the dynamic formation of neural circuitry which
grows as brain develops and relates to external world.Comment: LaTex file, 4 figures, 19 page
Dissipation and Topologically Massive Gauge Theories in Pseudoeuclidean Plane
In the pseudo-euclidean metrics Chern-Simons gauge theory in the infrared
region is found to be associated with dissipative dynamics. In the infrared
limit the Lagrangian of 2+1 dimensional pseudo-euclidean topologically massive
electrodynamics has indeed the same form of the Lagrangian of the damped
harmonic oscillator. On the hyperbolic plane a set of two damped harmonic
oscillators, each other time-reversed, is shown to be equivalent to a single
undamped harmonic oscillator. The equations for the damped oscillators are
proven to be the same as the ones for the Lorentz force acting on two particles
carrying opposite charge in a constant magnetic field and in the electric
harmonic potential. This provides an immediate link with Chern-Simons-like
dynamics of Bloch electrons in solids propagating along the lattice plane with
hyperbolic energy surface. The symplectic structure of the reduced theory is
finally discussed in the Dirac constrained canonical formalism.Comment: 22 pages, LaTe
Contact interaction in an unitary ultracold Fermi gas
An ultracold Fermi atomic gas at unitarity presents universal properties that
in the diluted limit can be well described by a contact interaction. By
employing a guide function with correct boundary conditions and making simple
modifications to the sampling procedure we are able to handle for the first
time a true contact interaction in a quantum Monte Carlo calculation. The
results are obtained with small variances. Our calculations for the Bertsch and
contact parameters are in excellent agreement with published experiments. The
possibility of using a more faithfully description of ultracold atomic gases
can help uncover features yet unknown of the ultracold atomic gases. In
addition, this work paves the way to perform quantum Monte Carlo calculations
for systems interacting with contact interactions, where in many cases the
description using potentials with finite effective range might not be accurate
Microvascular inflammation in atherosclerosis
Atherogenesis is the pathogenetic process leading to formation of the atheroma lesion. It is associated to a chronic inflammatory state initially stimulated by an aberrant accumulation of lipid molecules beyond the endothelial barrier. This event triggers a cascade of deleterious events mainly through immune cell stimulation with the consequent liberation of potent pro-inflammatory and tissue damaging mediators. The atherogenetic process implies marked modifications of endothelial cell functions and a radical change in the endothelial–leukocyte interaction pattern. Moreover, accumulating evidence shows an important link between microvascular and inflammatory responses and major cardiovascular risk factors. This review illustrates the current knowledge on the effects of obesity, hypercholesterolemia and diabetes on microcirculation; their pathophysiological implications will be discussed
- …