Irving Rondon - Academia.edu (original) (raw)

Papers by Irving Rondon

Journal of Physics: Condensed Matter, 2019

We analyze propagation of acoustic vortex beams in longitudinal synthetic magnetic fields. We sho... more We analyze propagation of acoustic vortex beams in longitudinal synthetic magnetic fields. We show how to generate two field configurations using a fluid contained in circulating cylinders: a uniform synthetic magnetic field hosting Laguerre-Gauss modes, and an Aharonov-Bohm flux tube hosting Bessel beams. For non-paraxial beams we find qualitative differences from the well-studied case of electron vortex beams in magnetic fields, arising due to the vectorial nature of the acoustic wave's velocity field. In particular, the pressure and velocity components of the acoustic wave can be individually sensitive to the relative sign of the beam orbital angular momentum and the magnetic field. Our findings illustrate how analogies between optical, electron, and acoustic vortex beams can break down in the presence of external vector potentials.

HAL (Le Centre pour la Communication Scientifique Directe), 2020

Using nonlinear mathematical models and experimental data from laboratory and clinical studies, w... more Using nonlinear mathematical models and experimental data from laboratory and clinical studies, we have designed new combination therapies against COVID-19. 1 Introduction Emerging viral diseases have caused significant global devastating pandemics, epidemics, and outbreaks (Smallpox, HIV, Polio, 1918 influenza, SARS-CoV, MERS-CoV, Ebola, SARS-CoV-2). Currently there are no approved treatments for any human coronavirus infection. Moreover, scientists do not know any treatment that would consistently cure COVID-19 patients. The world is facing a general catastrophe as people see the reality of alarming rises in infections, a building economic crisis, a shortage of ventilators, the lack of coronavirus testing, and many other disasters. The governments are desperate to find a solution. In some cases, they are even promoting unproven "remedies". The novel coronavirus presents an unprecedented challenge for everybody, including the scientists: the speed at which the virus spreads means they must accelerate their research. There is a wealth of literature dedicated to mathematical modeling of virus-immune-system interaction. See,

International Journal of Modern Physics B

We present a general growth model based on nonextensive statistical physics. We show that the mos... more We present a general growth model based on nonextensive statistical physics. We show that the most common unidimensional growth laws such as power law, exponential, logistic, Richards, Von Bertalanffy, Gompertz can be obtained. This model belongs to a particular case reported in (Physica A 369, 645 (2006)). The new evolution equation resembles the “universality” revealed by West for ontogenetic growth (Nature 413, 628 (2001)). We show that for early times the model follows a power law growth as [Formula: see text], where the exponent [Formula: see text] classifies different types of growth. Several examples are given and discussed.

Journal of Physics Communications, 2022

We present a general expression for the optical theorem in terms of Localized Waves. This represe... more We present a general expression for the optical theorem in terms of Localized Waves. This representation is well-known and commonly used to generate Frozen waves, Xwaves, and other propagation invariant beams. We analyze several examples using different input beam sources on a circular detector to measure the extinction cross-section.

Modern Physics Letters B, 2020

A general expression for the optical theorem for probe sources given in terms of propagation inva... more A general expression for the optical theorem for probe sources given in terms of propagation invariant beams is derived. This expression is obtained using the far field approximation for Rayleigh regime. In order to illustrate this results is revisited the classical and standard scattering elastic problem of a dielectric sphere for which the incident field can be any arbitrary invariant beam.

Optica Applicata, 2021

We present generalized expressions to calculate the orbital angular momentum for invariant beams ... more We present generalized expressions to calculate the orbital angular momentum for invariant beams using scalars potentials. The solutions can be separated into transversal electric TE, transversal magnetic TM and transversal electromagnetic TE/TM polarization modes. We show that the superposition of non-paraxial vectorial beams with axial symmetry can provide a well-defined orbital angular momentum and that the modes superposition affects the angular momentum flux density. The results are illustrated and analyzed for Bessel beams.

Journal of Physics Communications, 2021

The fundamental properties for the spin and orbital angular momentum are analyzed using acoustic ... more The fundamental properties for the spin and orbital angular momentum are analyzed using acoustic evanescent Bessel beams. The calculations reveal that the transversal spin, the canonical momentum, and the orbital angular momentum are proportional to the ratio l/ω where l is the topological charge and ω the angular frequency. This analysis shows that the complex acoustic Poynting vector and spin density exhibits interesting features related to the electromagnetic case.

Optik, 2017

Many practical applications require the analysis of electromagnetic scattering properties of loca... more Many practical applications require the analysis of electromagnetic scattering properties of local structures using different sources of illumination. The Optical Theorem (OT) is a useful result in scattering theory, relating the extinction of a structure to the scattering amplitude in the forward direction. The most common derivation of the OT is given for plane waves but advances in optical engineering now allow laser beam shaping, which might require an extended theorem where the impinging source is a structured field. In this work, we derive an expression for the optical theorem based on classical electromagnetic theory, for probe sources given in terms of propagation invariant beams. We obtain a general expression for the differential scattering cross section using the integral scattering amplitude approximation in the far field. We also analyze the scattering problem of a zero order Bessel beam by a dielectric sphere, under the Rayleigh approximation by varying the angle of incidence.

Progress In Electromagnetics Research B, 2016

We present a description of the electromagnetic field for propagation invariant beams using scala... more We present a description of the electromagnetic field for propagation invariant beams using scalar potentials. Fundamental dynamical quantities are obtained: energy density, Poynting vector and Maxwell stress tensor. As an example, all these quantities are explicitly calculated for the Bessel beams, which are invariant beams with circular cylindrical symmetry.

Physica A: Statistical Mechanics and its Applications, 2006

Journal of Physics: Conference Series, 2010

We investigate the propagation of kinks in inhomogeneous media. We show that the extended charact... more We investigate the propagation of kinks in inhomogeneous media. We show that the extended character of the kink, the internal mode instabilities and the phenomenon of disappearance of the translational mode can affect the kink motion in the presence of spacedependent external perturbations. We apply the results to the analysis of kink ratchets and the propagation of kinks driven by wave fields.

Chaos, Solitons & Fractals, 2004

We show that systems with non-invertible non-linearities can produce sequences of deterministical... more We show that systems with non-invertible non-linearities can produce sequences of deterministically independent values. We present autonomous dynamical systems that exhibit random behavior in such a way that all variables (taken separately) are unpredictable. We study a new mechanism for chaos in which a static system without inertial or dynamical elements can produce complexity. Using some results of exactly solvable chaotic systems we investigate the influence of different chaotic signals on the phenomenon of stochastic resonance. We report the results of real experiments concerning all these phenomena.

Wave Motion, 2018

Negative propagation is an uncommon response produced by the local sign change in Poynting vector... more Negative propagation is an uncommon response produced by the local sign change in Poynting vector components. We present a general Poynting vector expression for all invariant beams with cylindrical symmetry using scalar potentials in order to evaluate the possibility of negative propagation. We analyze the plausibility of negative propagation being independent of mode mixing; we study Weber beams as a particular case. The study of this negative effect allow us to advance in the field of micro manipulation and understanding of optical forces. Applications of these beams are discussed.