Institute Cibernetica

Havana, Cuba

Institute Cibernetica

Havana, Cuba
Time filter
Source Type

Jimenez J.C.,Institute Cibernetica | de la Cruz Cancino H.,Instituto Nacional Of Matematica Pura E Aplicada
BIT Numerical Mathematics | Year: 2012

There is a variety of strong Local Linearization (LL) schemes for the numerical integration of stochastic differential equations with additive noise, which differ with respect to the algorithm that is used in the numerical implementation of the strong Local Linear discretization. However, in contrast with the Local Linear discretization, the convergence rate of the LL schemes has not been studied so far. In this paper, two general theorems about this matter are presented and, with their support, additional results are derived for some particular schemes. As a direct application, the convergence rate of some strong LL schemes for SDEs with jumps is briefly expounded as well. © 2011 Springer Science + Business Media B.V.

Arenas Z.G.,Institute Cibernetica | Barci D.G.,State University of Rio de Janeiro
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

We present a functional formalism to derive a generating functional for correlation functions of a multiplicative stochastic process represented by a Langevin equation. We deduce a path integral over a set of fermionic and bosonic variables without performing any time discretization. The usual prescriptions to define the Wiener integral appear in our formalism in the definition of Green's functions in the Grassman sector of the theory. We also study nonperturbative constraints imposed by Becchi, Rouet and Stora symmetry (BRS) and supersymmetry on correlation functions. We show that the specific prescription to define the stochastic process is wholly contained in tadpole diagrams. Therefore, in a supersymmetric theory, the stochastic process is uniquely defined since tadpole contributions cancels at all order of perturbation theory. © 2010 The American Physical Society.

Arenas Z.G.,Institute Cibernetica | Arenas Z.G.,State University of Rio de Janeiro | Barci D.G.,State University of Rio de Janeiro
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

We present a supersymmetric formulation of Markov processes, represented by a family of Langevin equations with multiplicative white noise. The hidden symmetry encodes equilibrium properties such as fluctuation-dissipation relations. The formulation does not depend on the particular prescription to define the Wiener integral. In this way, different equilibrium distributions, reached at long times for each prescription, can be formally treated on the same footing. © 2012 American Physical Society.

Gonzalez A.,Institute Cibernetica
Revista Cubana de Fisica | Year: 2014

We suggest a possible correlation between the ionization events caused by the background neutron radiation and the experimental data on mutations with damage in the DNA repair mechanism, coming from the Long Term Evolution Experiment in E. Coli populations.

Cabo Montes de Oca A.,Institute Cibernetica
European Physical Journal Plus | Year: 2014

The form of the resulting Feynman propagators in a proposed local and gauge invariant QCD for massive fermions suggests the existence of indefinite metric associated to quark states, a property that might relate it with the known Lee-Wick theories. Thus, the nature of the asymptotic free quark states in the theory is investigated here by quantizing the quadratic part of the quark action. As opposite to the case in the standard QCD, the free theory does not show Hamiltonian constraints. The propagation modes include a family of massless waves and a complementary set of massive oscillations. The theory can be quantized in a way that the massive modes show positive metric and the massless ones exhibit negative norms. It is remarked that, since QCD is expected to not exhibit gluon or quark asymptotic states, the presence of negative metric massless modes does not constitute a definite drawback of the theory. In addition, the fact that the positive metric quark states are massive, seems to be a good feature of the model, being consistent with the approximate existence of asymptotically free massive states in high-energy processes. © 2014 Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg.

Valdes A.A.,Institute Cibernetica
IFMBE Proceedings | Year: 2013

The present paper proposes a model of the Healthcare Technology Management in a hospital, with systemic focus. It has been developed using the Business Process Management (BPM), a technology that provides methods and tools, with process focus. This model defines the processes that intervene in this activity, as well as measuring, control and improve them. The proposed model can be established as work tool in the Healthcare Technology Management and as starting point for the design of an automatic system; therefore, it will allow reaching sustainability and operational security and increasing the features of the healthcare equipment in a hospital. © 2013 Springer.

Rodriguez O.,Institute Cibernetica
IFMBE Proceedings | Year: 2013

The detection of the acoustic contact between the ultrasound (US) transducer and the patient skin is a main issue to consider in the design of the therapeutic US generating system. It has been reported that it can be obtained a substantial increment in the bandwidth where the mentioned detection can be implemented, by a method that uses the phase variations of the transducer electric impedance produced by the variations of the external acoustic load. This article focuses on the losses that can occur in the therapeutic US transducer in normal operation and with a deficient acoustic contact with the load. It was found that the referred phase approach can imply in addition to the extended bandwidth, a substantial reduction of the losses that can arise in the transducer. Quantitatively, it was computed that for the phase approach regarding the classic design, the losses are reduced up to 20% and 65% approximately, for the investigated emissions in water and air respectively, for 25 mm diameter PZT-4 transducers working at a frequency of 1 MHz. According to our knowledge, this is the first time that it is reported a comparative numerical analysis in relation to these losses. © 2013 Springer.

Otero J.A.,Institute Cibernetica | Rodriguez-Ramos R.,University of Habana | Monsivais G.,National Autonomous University of Mexico | Stern C.,National Autonomous University of Mexico | Lebon F.,CNRS Laboratory of Mechanics and Acoustics
Philosophical Magazine Letters | Year: 2013

We study the propagation of shear horizontal waves between the interface of piezoelectric and piezomagnetic half-spaces with a magneto-electro-mechanical imperfect contact. Mechanical, electrical and magnetical imperfections are modelled by means of a spring, a capacitor and a inductor, respectively. A general expression for the dispersion relation not reported previously in literature is given in an explicit form, with the diverse limit cases analysed in detail. In some of these limit cases, new expressions are also obtained which predict the existence of interfacial waves. In the other cases, when already reported results exist, a comparison with them is done. Some physical interpretations are derived from the limit cases. The influence of mechanical, electrical and magnetical imperfect contacts are shown in some numerical examples. © 2013 Taylor and Francis Group, LLC.

Ferrer E.J.,University of Texas at El Paso | De La Incera V.,University of Texas at El Paso | Paret D.M.,University of Habana | Martinez A.P.,Institute Cibernetica | Sanchez A.,National Autonomous University of Mexico
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EOS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (eB>m2), the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EOS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EOS at any field value. © 2015 American Physical Society.

Acosta Avalo J.L.,Instituto Superior Of Tecnologias Y Ciencias Aplicadas Instec | Perez Rojas H.,Institute Cibernetica
Nuclear Physics B | Year: 2016

We report the generation of a pseudovector electric current having imbalanced chirality in an electron-positron strongly magnetized gas in QED. It propagates along the external applied magnetic field B as a chiral magnetic effect in QED. It is triggered by a perturbative electric field parallel to B, associated to a pseudovector longitudinal mode propagating along B. An electromagnetic chemical potential was introduced, but our results remain valid even when it vanishes. A nonzero fermion mass was assumed, which is usually considered vanishing in the literature. In the quantum field theory formalism at finite temperature and density, an anomaly relation for the axial current was found for a medium of massive fermions. It bears some analogy to the Adler-Bell-Jackiw anomaly. From the expression for the chiral current in terms of the photon self-energy tensor in a medium, it is obtained that electrons and positrons scattered by longitudinal photons (inside the light cone) contribute to the chiral current, as well as the to pair creation due to longitudinal photons (out of light cone). In the static limit, an electric pseudovector current is obtained in the lowest Landau level. © 2016 The Authors.

Loading Institute Cibernetica collaborators
Loading Institute Cibernetica collaborators