37,968 research outputs found
Greater Resistencia Study Case: Greenfield and Increased Densification
. This paper focuses on one of the relevant issues of the phenomena of urban expansion and densification, i.e. the lack of planning of public greenfields. At the regional level, since 2001, Resistencia City Council has been promoting a growth in height by increasing built-up areas in central districts that have complete infrastructure, through the implementation of the Ordinance 5403/01 - high density. On the other hand, in the last 10 years the population growth of the city (16%) has been followed by an increase in the supply of open space per inhabitant (85%). However, this increase is not reflected in the inner city areas, where the higher population density is located. This paper aims to analyze and relate the results arising, so far, from the densification of central areas and its relationship with the availability of open space in central districts of Greater Resistencia City
Coherent States of Accelerated Relativistic Quantum Particles, Vacuum Radiation and the Spontaneous Breakdown of the Conformal SU(2,2) Symmetry
We give a quantum mechanical description of accelerated relativistic
particles in the framework of Coherent States (CS) of the (3+1)-dimensional
conformal group SU(2,2), with the role of accelerations played by special
conformal transformations and with the role of (proper) time translations
played by dilations. The accelerated ground state of first
quantization is a CS of the conformal group. We compute the distribution
function giving the occupation number of each energy level in
and, with it, the partition function Z, mean energy E and entropy S, which
resemble that of an "Einstein Solid". An effective temperature T can be
assigned to this "accelerated ensemble" through the thermodynamic expression
dE/dS, which leads to a (non linear) relation between acceleration and
temperature different from Unruh's (linear) formula. Then we construct the
corresponding conformal-SU(2,2)-invariant second quantized theory and its
spontaneous breakdown when selecting Poincar\'e-invariant degenerated
\theta-vacua (namely, coherent states of conformal zero modes). Special
conformal transformations (accelerations) destabilize the Poincar\'e vacuum and
make it to radiate.Comment: 25 pages, LaTeX, 3 figures. Additional information (resulting in four
extra pages) and a slight change of focus has been introduced in order to
make the line of arguments more clear. Title changed accordingl
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