Canonical Discontinuous Planar Piecewise Linear Systems

The family of Filippov systems constituted by planar discontinuous piecewise linear systems with two half-plane linearity zones is considered. Under generic conditions that amount to the boundedness of the sliding set, some changes of variables and parameters are used to obtain a Li´enard-like canonical form with seven parameters. This canonical form is topologically equivalent to the original system if one restricts one’s attention to orbits with no points in the sliding set. Under the assumption of focus-focus dynamics, a reduced canonical form with only five parameters is obtained. For the case without equilibria in both open half-planes we describe the qualitatively different phase portraits that can occur in the parameter space and the bifurcations connecting them. In particular, we show the possible existence of two limit cycles surrounding the sliding set. Such limit cycles bifurcate at certain parameter curves, organized around different codimension-two Hopf bifurcation points. The proposed canonical form will be a useful tool in the systematic study of planar discontinuous piecewise linear systems, in which this paper is a first step

Silvino : una sola batalla

Silvino, una sola batalla, revela una faceta de la violencia en Colombia a partir de un personaje totalmente invisible perteneciente a la clase media. Silvino, aunque ha sido una víctima directa de la violencia nunca se ha visto afectado de forma física. Ha tenido la oportunidad de vivirla de frente en todas sus aristas. Es a través de su historia de vida que se logra profundizar en hechos trascendentales para Colombia que dieron pasos a escenarios nefastos como el bipartidismo, enfrentamientos entre grupos armados y las diferentes formas de maltrato por parte de los mismos con la población. Después de 60 años de violencia resulta indignante e increíble que un país como Colombia se niegue a un proceso de paz. El presente estudio pretende aportar a la construcción de la memoria histórica para la no repetición y a las diferentes generaciones.Comunicador (a) SocialPregrad

Conocimiento y actitudes en farmacovigilancia y notificación de reacciones adversas a medicamentos en el Centro de Salud Sauces III. 2021

La investigación tuvo como objetivo relacionar el conocimiento y actitudes en Farmacovigilancia y notificación de reacciones adversas a medicamentos de los profesionales sanitarios del Centro de Salud Sauces III, 2021. El estudio fue de tipo observacional, prospectivo, transversal y analítico. Se utilizó dos cuestionarios para recolección de datos, y evaluar los conocimientos y la escala de Likert para medir la actitud frente a Farmacovigilancia y notificación de reacciones adversas medicamentosas. Se encontró que 49 profesionales sanitarios del Centro de Salud Sauces III durante el 2021 presentaron un conocimiento sobre farmacovigilancia regular de 55,10% y de 44,90 alto. Seguido del 33,33 % como desfavorable de sus respuestas y finalmente el 41,18 % presenta una actitud favorable. El Chi-cuadrado de Pearson fue de 0,58, con una significación asintótica de 0,201 Los profesionales que contestaron correctamente al conocimiento de la normativa fue un 61,22%; el 59,18% tiene un nivel alto en el conocimiento de la organización y el 75,51 % tienen conocimiento regular del sistema de farmacovigilancia. En conclusión, no existe relación significativa entre el conocimiento y actitud en Farmacovigilancia y notificación de reacciones adversas medicamentosa de los profesionales sanitarios

The Focus-Center-Limit Cycle Bifurcation in Symmetric 3D Piecewise Linear Systems

The birth of limit cycles in 3D (three-dimensional) piecewise linear systems for the relevant case of symmetrical oscillators is considered. A technique already used by the authors in planar systems is extended to cope with 3D systems, where a greater complexity is involved. Under some given nondegeneracy conditions, the corresponding theorem characterizing the bifurcation is stated. In terms of the deviation from the critical value of the bifurcation parameter, expressions in the form of power series for the period, amplitude, and the characteristic multipliers of the bifurcating limit cycle are also obtained. The results are applied to accurately predict the birth of symmetrical periodic oscillations in a 3D electronic circuit genealogically related to the classical Van der Pol oscillator.Ministerio de Ciencia y Tecnología DPI2000-1218-C04-04Ministerio de Ciencia y Tecnología BFM2001-2668Ministerio de Ciencia y Tecnología BFM2003-00336Junta de Andalucía TIC-13

Bifurcation patterns in homogeneous area-preserving piecewise-linear maps

The dynamical behavior of a family of planar continuous piecewise linear maps with two zones is analyzed. Assuming homogeneity and preservation of areas we obtain a canonical form with only two parameters: the traces of the two matrices defining the map. It is shown the existence of sausage-like structures made by lobes linked at the nodes of a nonuniform grid in the parameter plane. In each one of these structures, called resonance regions, the rotation number of the associated circle map is a given rational number. The boundary of the lobes and a significant inner partition line are studied with the help of some Fibonacci polynomials.Postprint (author's final draft

Potential interactions in a cohort of elderly hiv-positive patients

Abstract: Objective: The increase of HIV-patients life expectancy leads to a new model of patient with chronic diseases and polymedicated. For this reason we ought to know in clinical practice the prevalence of polypharmacy and drug-drug interactions between the antiretroviral drugs and comedication in our patients in order to identify and prevent them. Method: A retrospective, descriptive study carried out in > 50 years old patients on antiretroviral treatment. Results: We included 242 patients of whom 148 (61%) were receiving concomitant treatment. 243 potential interactions were detected, where 197 are considered moderate and 46 severe, affecting 110 patients. 35 (76%) interactions were related to boosted protease inhibitors. The main consequence of these interactions was the increase in plasma concentrations of comedication (48%). Statins were the comedication most involved in severe drug-druginteractions (24%), followed by inhaled corticosteroids (15%). Conclusions: Polypharmacy was found in about half of our study population and the prevalence of drug-drug interactions was high. Hospital pharmacists may play a crucial role in their detection, management and early communication

Membrane fission versus cell division: When membrane proliferation is not enough

Cell division is a process that produces two or more cells from one cell by replicating the original chromosomes so that each daughter cell gets a copy of them. Membrane fission is a process by which a biological membrane is split into two new ones in suchamanner that the contents of the initial membrane get distributedor separated among the new membranes. Inspired by these biological phenomena, new kinds of models we reconsidered in the discipline of Membrane Computing, in the context of P systems with active membranes, and tissue P systems that use symport/antiport rules, respectively. This paper combines the two approaches: cell-like P systems with symport/antiport rules and membrane separation are studied, from a computational complexity perspective.Specifically, the role of the environment in the context of cell-like P systems withmembrane separation is established, and additional borderlines between tractability and NP-hardness are summarized.Ministerio de Economía y Competitividad TIN2012- 3743