arXiv subjects

Jorge A. González

Publications and source records attributed to Jorge A. González.

6 recordsLinked to original sources

arXiv2024

Highly-enhanced propagation of long-range kinks in heterogeneous media

We investigate a field-theoretical model that describes the interaction between kinks and antikinks and between kinks and other heterogeneous fields and impurities. We show that the long-range kink can tunnel through a barrier created by heterogeneous fields and impurities even when the energy of the center of mass of the kink is less than the height of the energy barrier. We also study the conditions under which the kink can pass freely through a disordered medium. We introduce the concept of "effective translational symmetry". We compare our results with those from recent papers published in this journal, where the Bogomol'nyi-Prasad-Sommerfield property is discussed.

nlin.PS↗

arXiv2019

Stability of bubble-like fluxons in disk-shaped Josephson junctions in the presence of a coaxial dipole current

We investigate analytically and numerically the stability of bubble-like fluxons in disk-shaped heterogeneous Josephson junctions. Using ring solitons as a model of bubble fluxons in the two-dimensional sine-Gordon equation, we show that the insertion of coaxial dipole currents prevents their collapse. We characterize the onset of instability by introducing a single parameter that couples the radius of the bubble fluxon with the properties of the injected current. For different combination of parameters, we report the formation of stable oscillating bubbles, the emergence of internal modes, and bubble breakup due to internal mode instability. We show that the critical germ depends on the ratio between its radius and the steepness of the wall separating the different phases in the system. If the steepness of the wall is increased (decreased), the critical radius decreases (increases). Our theoretical findings are in good agreement with numerical simulations. We discuss applications in quantum information technologies.

nlin.PS↗

arXiv2019

New combinational therapies for cancer using modern statistical mechanics

We investigate a new dynamical system that describes tumor-host interaction. The equation that describes the untreated tumor growth is based on non-extensive statistical mechanics. Recently, this model has been shown to fit successfully exponential, Gompertz, logistic, and power-law tumor growths. We have been able to include as many hallmarks of cancer as possible. We study also the dynamic response of cancer under therapy. Using our model, we can make predictions about the different outcomes when we change the parameters, and/or the initial conditions. We can determine the importance of different factors to influence tumor growth. We discover synergistic therapeutic effects of different treatments and drugs. Cancer is generally untreatable using conventional monotherapy. We consider conventional therapies, oncogene-targeted therapies, tumor-suppressors gene-targeted therapies, immunotherapies, anti-angiogenesis therapies, virotherapy, among others. We need therapies with the potential to target both tumor cells and the tumors' microenvironment. Drugs that target oncogenes and tumor-suppressor genes can be effective in the treatment of some cancers. However, most tumors do reoccur. We have found that the success of the new therapeutic agents can be seen when used in combination with other cancer-cell-killing therapies. Our results have allowed us to design a combinational therapy that can lead to the complete eradication of cancer.

physics.bio-ph↗

arXiv2017

Bubble-like structures generated by activation of internal shape modes in two-dimensional sine-Gordon line solitons

Nonlinear waves that collide with localized defects exhibit complex behavior. Apart from reflection, transmission, and annihilation of an incident wave, a local inhomogeneity can activate internal modes of solitons, producing many impressive phenomena. In this work, we investigate a two-dimensional sine-Gordon model perturbed by a family of localized forces. We observed the formation of bubble-like and drop-like structures due to local internal shape modes instabilities. We describe the formation of such structures on the basis of a one-dimensional theory of activation of internal modes of sG solitons. An interpretation of the observed phenomena, in the context of phase transitions theory, is given. Implications in Josephson junctions with a current dipole device are discussed.

nlin.PS↗

arXiv2012

Highly-complex optical signal generation using electro-optical systems with non-linear, non-invertible transmission functions

We present a scheme whereby a static non-linear, non-invertible transmission function performed by the electro-optic Mach-Zehnder modulator produces highly complex optical chaos. The scheme allows the deterministic transformation of low-dimensional band-limited chaotic signals into much higher-dimensional structures with broadband spectra and without using any delay elements or feedback. Standard benchmark tests show that all the considered complexity indices are highly increased due to this transformation in a controlled fashion. This mechanism allows the design of simple optoelectronic delayed oscillators with extremely complex chaotic output.

nlin.CD↗

arXiv2006

Cancer and nonextensive statistics

We propose a new model of cancer growth based on nonextensive entropy. The evolution equation depends on the nonextensive parameter q. The exponential, the logistic, and the Gompertz growth laws are particular cases of the generalized model. Experimental data of different tumors have been shown to correspond to all these tumor-growth laws. Recently reported studies suggest the existence of tumors that follow a power law behavior. Our model is able to fit also these data for q<1. We show that for q<1, the commonly used constant-intensity therapy is unable to reduce the tumor size to zero. As is the case of the Gompertzian tumors, for- q<1 a late-intesification schedule is needed. However, these tumors with q<1 are even harder to cure than the Gompertzian ones. While for a Gompertzian tumor a linearly-increasing cell-kill function is enough to reduce the tumor size to zero following an exponential decay, in the case of tumors with q<1, the exponential decay is obtained only with an exponentially increasing cell-kill function. This means that these tumors would need an even more aggressive treatment schedule. We have shown that for Gompertzian tumors a logarithmic late-intensification is sufficient for the asymptotic reduction of the tumor-size to zero. This is not the fastest way but it is more tolerable for patients. However for the tumors with q<1 we would need at least a linearly increasing therapy in order to achieve a similarly effective reduction. When q>1, tumor size can be reduced to zero using a traditional constant-intensity therapy.

physics.med-ph↗