PubMed Health⌕ Search

Biomedical subjects

A Plastino

Publications and source records attributed to A Plastino.

At least 19 recordsLinked to original sources
PubMed2006

EEG analysis using wavelet-based information tools.

Wavelet-based informational tools for quantitative electroencephalogram (EEG) record analysis are reviewed. Relative wavelet energies, wavelet entropies and wavelet statistical complexities are used in the characterization of scalp EEG records corresponding to secondary generalized tonic-clonic epileptic seizures. In particular, we show that the epileptic recruitment rhythm observed during seizure development is well described in terms of the relative wavelet energies. In addition, during the concomitant time-period the entropy diminishes while complexity grows. This is construed as evidence supporting the conjecture that an epileptic focus, for this kind of seizures, triggers a self-organized brain state characterized by both order and maximal complexity.

Adolescent↗
PubMed2005

Reciprocity relations between ordinary temperature and the Frieden-Soffer Fisher temperature.

Frieden and Soffer conjectured some years ago [Phys. Rev. E 52, 2274 (1995)] the existence of a "Fisher temperature" T(F) that would play, with regards to Fisher's information measure I , the same role that the ordinary temperature T plays in relation to Shannon's logarithmic measure. Here we exhibit the existence of reciprocity relations between T(F) and T and provide an interpretation with reference to the meaning of T(F) for the canonical ensemble.

Journal Article↗
PubMed2004

Constructive approximations to the q=1/2 maximum entropy distribution from redundant and noisy data.

The problem of constructing the q=1/2 nonextensive maximum entropy distributions from redundant and noisy data is considered. A strategy is proposed, which evolves through the following steps. (i) Independent constraints are first preselected by recourse to a data-independent technique to be discussed here. (ii) The data are a posteriori used to determine the parameters of the distribution by a previously introduced forward approach. (iii) A backward approach is proposed for reducing the parameters of such distribution. The previously introduced forward approach is generalized here in order to make it suitable for dealing with very noisy data.

Journal Article↗
PubMed2004

Heisenberg-Fisher thermal uncertainty measure.

We establish a connection among (i) the so-called Wehrl entropy, (ii) Fisher's information measure I(beta), and (iii) the canonical ensemble entropy for the one-dimensional quantum harmonic oscillator (HO). We show that the contribution of the excited HO spectrum to the mean thermal energy is given by I(beta), while the pertinent canonical partition function is essentially given by another Fisher measure: the so-called shift invariant one. Our findings should be of interest in view of the fact that it has been shown that the Legendre transform structure of thermodynamics can be replicated without any change if one replaces the Boltzmann-Gibbs-Shannon entropy by Fisher's information measure [Phys. Rev. E 60, 48 (1999)]]. Fisher-related uncertainty relations are also advanced, together with a Fisher version of thermodynamics' third law.

Journal Article↗
PubMed2003

Nonequilibrium thermodynamics and Fisher information: sound wave propagation in a dilute gas.

As recently shown, a constrained Fisher-information extremizing (CFIE) process is able to deal with both equilibrium and nonequilibrium thermodynamic processes, thus being able to reproduce results deduced by a recourse to Boltzmann's transport equation (BTE). Here, we discuss the propagation of sound waves in a dilute gas and compare the ensuing CFIE solutions with those obtained by a recourse to Grad's approach to the BTE. The final molecular distribution function arrived at is the same following two alternative routes, either (i) the BTE via the Grad approach or (ii) the constrained Fisher treatment that does not require the use of the BTE. The way the necessary a priori information is used in these two instances, is however, quite different.

Journal Article↗
PubMed2002

Schrödinger link between nonequilibrium thermodynamics and Fisher information.

It is known that equilibrium thermodynamics can be deduced from a constrained Fisher information extemizing process. We show here that, more generally, both nonequilibrium and equilibrium thermodynamics can be obtained from such a Fisher treatment. Equilibrium thermodynamics corresponds to the ground-state solution, and nonequilibrium thermodynamics corresponds to excited-state solutions, of a Schrödinger wave equation (SWE). That equation appears as an output of the constrained variational process that extremizes Fisher information. Both equilibrium and nonequilibrium situations can thereby be tackled by one formalism that clearly exhibits the fact that thermodynamics and quantum mechanics can both be expressed in terms of a formal SWE, out of a common informational basis. As an application, we discuss viscosity in dilute gases.

Journal Article↗
PubMed2002

Recursive approach for constructing the q=1/2 maximum entropy distribution from redundant data.

A recursive approach for computing the q=1/2 nonextensive maximum entropy distribution of the previously introduced formalism for data subset selection is proposed. Such an approach is based on an iterative biorthogonalization technique, which allows for the incorporation of the Lagrange multipliers that determine the distribution to the workings of the algorithm devised for selecting relevant data subsets. This technique circumvents the necessity of inverting operators and yields a recursive procedure to appropriately modify the Lagrange multipliers so as to account for each new constraint.

Journal Article↗
PubMed2002

Classical no-cloning theorem.

A classical version of the no-cloning theorem is discussed. We show that an arbitrary probability distribution associated with a (source) system cannot be copied onto another (target) system while leaving the original distribution of the source system unperturbed. For classical dynamical systems such a perfect cloning process is not permitted by the Liouvillian (ensemble) evolution associated with the joint probability distribution of the composite source-target-copying machine system.

Journal Article↗
PubMed2001

Nonextensive maximum-entropy-based formalism for data subset selection.

A method for data subset selection, which is based on the q=1 / 2 maximum information measure formalism, is proposed. The method evolves iteratively by selecting, at each iteration, the measure yielding a q=1 / 2 distribution capable of making predictions minimizing the Euclidean distance to the available data.

Journal Article↗
PubMed2001

Population genetics from an information perspective.

Some basic effects of population genetics are derived governing the occurrences of alleles A(i)and genotypes A(i)A(j)among its members. A principle of extreme physical information (EPI) is used. These effects are (1) the equation of genetic change, (2) Fisher's theorem of partial change, (3) a new uncertainty principle, and (4) the monotonic decrease of Fisher information with time, indicating increased disorder for the population. General conditions of population change are allowed: fitness coefficients w(ij)generally changing with time [except in effect (2)], population randomly or non-randomly mating, and a general number of loci present within each chromosome. EPI is a practical tool for deriving probability laws. It is an outgrowth of a physical process that occurs during any act of measurement. Here the measurement is the random observation of a genotype A(i)A(j). This observation is to be used to estimate the time of the observation, called "evolutionary time". The measurement activity incurs errors in the estimated observation time and fitness value of the observed genotype. By the Cramer-Rao inequality, the product of the two uncertainties must exceed unity [effect (3)]. The Fisher information I in data space is postulated to originate in the space of the genotype where it had some generally larger value J. The EPI principle extremizes the loss of information (I--J) with I=1/2 J. The solution gives rise to effects (1) and (2). Finally, it is shown that effect (4) holds when the population approaches an equilibrium state, e.g. for time values greater than a threshold if fitness coefficients w(ij)are constant. EPI provides a common framework for deriving physical laws and laws of population genetics. The new effects (3) and (4) are confirmed through computer simulation.

Animals↗
PubMed2000

Naudts-like duality and the extreme fisher information principle

We show that using Frieden and Soffer's extreme information principle [Phys. Rev. E 52, 2274 (1995)] with a Fisher measure constructed with escort probabilities [C. Beck and F. Schlogel, Thermodynamics of Chaotic Systems (Cambridge University Press, Cambridge, England, 1993)], the concomitant solutions obey a type of Naudts's duality (e-print cond-mat/990470) for nonextensive ensembles [C. Tsallis, in Nonextensive Statistical Mechanics and its Applications, Lecture Notes in Physics, edited by S. Abe and Y. Okamoto (Springer-Verlag, Berlin, in press)].

Journal Article↗
PubMed2000

Frame-theory-based approach for determining the time-frequency distribution characterizing a dense group of reflecting objects

An inverse-scattering problem concerning the determination of a time-frequency spreading function is addressed. Such a function characterizes a dense group of reflecting objects at different ranges and moving with different velocities. The problem, arising in radar and other remote-sensing techniques, is a classical inverse problem. The aim is to reconstruct a function of two variables by means of signals (of one variable) reflected from the environment being observed. The proposed approach is developed by recourse to the frame theory in order to provide a reconstruction formula that asymptotically converges to a unique spreading function. The realistic situation with respect to the transmission of a finite number of signals is further considered. In this case the reconstruction formula is shown to yield the orthogonal projection of the spreading function onto a subspace generated by the outgoing signals.

Journal Article↗
PubMed1999

Fisher-based thermodynamics: its Legendre transform and concavity properties.

It is shown that the Legendre-transform structure of thermodynamics can be replicated without any change if one replaces the entropy S by Fisher's information measure I. Also, the important thermodynamic property of concavity is shown to be obeyed by I. By this use of the Fisher information measure we develop a thermodynamics that seems to be able to treat equilibrium and nonequilibrium situations in a manner entirely similar to the conventional one.

Journal Article↗