104 research outputs found
Energetic model of tumor growth
A macroscopic model of the tumor Gompertzian growth is proposed. This
approach is based on the energetic balance among the different cell activities,
described by methods of statistical mechanics and related to the growth
inhibitor factors. The model is successfully applied to the multicellular tumor
spheroid data.Comment: 5 pages, 2 figures, contribution to "Complexity, Metastability and
Nonextensivity", Erice, July 200
Symmetry breaking in non-commutative cut-off field theories
The relation between symmetry breaking in non-commutative cut-off field
theories and transitions to inhomogeneous phases in condensed matter and in
finite density QCD is discussed. The non-commutative dynamics, with its
peculiar infrared-ultraviolet mixing, can be regarded as an effective
description of the mechanisms which lead to inhomogeneous phase transitions and
a roton-like excitation spectrum.Comment: LaTex, 3 pages,Talk given at "Quark Confinement and the Hadron
Spectrum VI", 21-25 September 2004, Villasimius, Ital
Holographic Bound in Quantum Field Energy Density and Cosmological Constant
The cosmological constant problem is reanalyzed by imposing the limitation of
the number of degrees of freedom (d.o.f.) due to entropy bounds directly in the
calculation of the energy density of a field theory. It is shown that if a
quantum field theory has to be consistent with gravity and holography, i.e.
with an upper limit of storing information in a given area, the ultraviolet
momentum cut-off is not the Planck mass, M_p, as naively expected, but
M_p/N_U^(1/4) where N_U is the number of d.o.f. of the universe. The energy
density evaluation turns out completely consistent with Bousso's bound on the
cosmological constant value. The scale M_p/N_U^(1/4), that in the "fat
graviton" theory corresponds to the graviton size, originates by a selfsimilar
rearrangement of the elementary d.o.f. at different scales that can be seen as
an infrared-ultraviolet connection.Comment: Submitted to PRD, more accurate reference
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