9,016 research outputs found
Symbolic Sequences and Tsallis Entropy
We address this work to investigate symbolic sequences with long-range
correlations by using computational simulation. We analyze sequences with two,
three and four symbols that could be repeated times, with the probability
distribution . For these sequences, we verified that
the usual entropy increases more slowly when the symbols are correlated and the
Tsallis entropy exhibits, for a suitable choice of , a linear behavior. We
also study the chain as a random walk-like process and observe a nonusual
diffusive behavior depending on the values of the parameter .Comment: Published in the Brazilian Journal of Physic
The Contribution of the Smectic-Nematic Interface to the Surface Energy
The contribution of the smectic-nematic interface to the surface energy of a
nematic liquid crystal sample is analyzed. By means of a simple model it is
shown that the surface energy depends on the thickness of the region over which
the transition smectic-nematic takes place. For perfectly flat substrates this
thickness is of the order of the correlation length entering in the transition.
An estimate of this contribution shows that it is greater than the one arising
from the nematic-substrate interaction. Moreover, it is also shown that the
surface energy determined in this way presents a non-monotonic behavior with
the temperature.Comment: 10 pages, revte
Geometry, stochastic calculus and quantum fields in a non-commutative space-time
The algebras of non-relativistic and of classical mechanics are unstable
algebraic structures. Their deformation towards stable structures leads,
respectively, to relativity and to quantum mechanics. Likewise, the combined
relativistic quantum mechanics algebra is also unstable. Its stabilization
requires the non-commutativity of the space-time coordinates and the existence
of a fundamental length constant. The new relativistic quantum mechanics
algebra has important consequences on the geometry of space-time, on quantum
stochastic calculus and on the construction of quantum fields. Some of these
effects are studied in this paper.Comment: 36 pages Latex, 1 eps figur
AN OBJECTIVE EXPLICIT FORMULATION BASED ON THE OLDROYD-B CONSTITUTIVE EQUATION
In the present paper is shown how to obtain an objective explicit algebraic
extra-stress model (AESM) based on differential constitutive equations for
viscoelastic flows (Oldroyd B, White-Metzner, Phan-Thien-Tanner, etc).
The formulation is developed for three-dimensional time-dependent flows.
In a previous work, Mompean, 1998 obtained a non-objective algebraic
model. This inconsistency is now removed introducing the relative-rate-ofrotation
tensor making the model frame-invariant. A new generalized
objective time derivative is also introduced, giving flexibility to the model.
Calculations are performed with an Oldroyd B based AESM for a 4:1
contraction flow, showing good agreement with the original constitutive
differential model. Several results with particular derivatives are obtained
and an analysis guided by a flow type classifier is given. This formulation
is able to include a prediction, not present in the Oldroyd B model, the
viscometric second normal stress difference, N2
Soft singularity and the fundamental length
It is shown that some regular solutions in 5D Kaluza-Klein gravity may have
interesting properties if one from the parameters is in the Planck region. In
this case the Kretschman metric invariant runs up to a maximal reachable value
in nature, i.e. practically the metric becomes singular. This observation
allows us to suppose that in this situation the problems with such soft
singularity will be much easier resolved in the future quantum gravity then by
the situation with the ordinary hard singularity (Reissner-Nordstr\"om
singularity, for example). It is supposed that the analogous consideration can
be applied for the avoiding the hard singularities connected with the gauge
charges.Comment: 5 page
Study of the influence of ethylene oxide sterilization variables on Bacillus subtilis inactivation
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