Solución débil de un problema hiperbólico de tipo escalar

En este artículo se encuentra una solución débil para una ecuación hiperbólica de tipo escalar utilizando el método de compacidad compensadaIn this expository paper we present a weak solution for a hyperbolic equation. The method of compensated compactness is use

Algoritmo de Encriptación para Imágenes a color basado en Sistemas Caóticos

Context: Taking advantage of the foundations of the theory of non-linear dynamic systems, we propose an encryption model for color images based on chaotic systems, which satisfies security standards in accordance with the challenges faced by society. Method: A symmetrical algorithm is proposed using Arnold's chaotic Cat system for permutation and for diffusion Chen's hyperchaotic system or Lorenz's hyperchaotic system, a parallel programming in implementation is used to reduce execution times. Results:Performance metrics are applied to evaluate the security of the proposed cryptographic model, finding that the indicators obtained are framed within those published in recent articles that address the problem of security through chaos. Conclusions: The results obtained confirm that the use of chaos theory as a tool for strengthening security schemes in communications is a good alternative, particularly when referring to image transfer. Contexto: Aprovechando los fundamentos de la teoría de sistemas dinámicos no lineales se propone un modelo de encriptación para imágenes a color basado en sistemas caóticos, que satisface estándares de seguridad acordes con los desafíos a que se enfrenta la sociedad. Método:  Se propone un algoritmo simétrico utilizando el sistema caótico Cat de Arnold para la permutación y para la difusión el sistema hipercaótico de Chen o el sistema hipercaótico de Lorenz, en la implementación se utiliza programación paralela para reducir los tiempos de ejecución. Resultados: Se aplican métricas de desempeño para evaluar la seguridad del modelo criptográfico propuesto, encontrando que los indicadores obtenidos se enmarcan dentro de los publicados en artículos recientes que  abordan el problema de la seguridad a través del caos. Conclusiones: Se aplican métricas de desempeño para evaluar la seguridad del modelo criptográfico propuesto, encontrando que los indicadores obtenidos se enmarcan dentro de los publicados en artículos recientes que  abordan el problema de la seguridad a través del caos

Links between recent trends in airborne pollen concentration, meteorological parameters and air pollutants

[EN] Biogenic aerosols may play an active role in various diseases. Pollutant gases and bioaerosols coexist in the atmosphere with the possibility of interacting with each other increasing their adverse impacts on human health. The study of long-term trends and the correlation between the pollen concentration from selected taxa (especially those related to allergies) and both the main atmospheric pollutants and the meteorological parameters has enabled us to identify the main factors that affect pollen concentration in the atmosphere. This study analyzes the long-term trend in CO, NO, NO2, PM10, SO2 and O3 from 1997 to 2016 and Fraxinus, Poaceae and Populus pollen concentrations in the city of León from 1994 to 2016. In general, there is a significant decreasing trend in atmospheric pollutant concentrations and a significant increasing trend in Fraxinus pollen concentrations. In addition, the influence of air pollutants and climatic factors on pollen concentrations and pollination period duration was studied using the Spearman correlation, showing that the flowering and pollination periods depend largely of the weather conditions before these periods and are influenced by air pollutant concentrationsSISpanish Ministry of Economy and Competitiveness (Grant TEC2014-57821-R), the University of León (Programa Propio 2015/00054/001 and 2018/00203/001) and AERORAIN project (Ministry of Economy and Competitiveness, Grant CGL2014-52556-R, co-financed with FEDER funds). F. Oduber acknowledges the grant BES-2015-074473 from the Spanish Ministry of Economy and Competitiveness. C. Blanco-Alegre acknowledges the grant FPU16-05764 from the Spanish Ministry of Education, Culture and Spor

Algoritmo de Encriptación de Imágenes Utilizando el Atractor Caótico de Lorenz

Context: With the increasing volumes of information generated in real time, novel mechanisms area needed to ensure security so as to prevent access to unauthorized people. The conventional encryption methods are not appropriate for images, because they are prone to statistical attacks due to the strong correlation between adjacent pixels and the analysis of color gamut histograms, which can help to identify them within the image; with this aim in mind, in this paper an algorithm for image encryption using chaotic attractors is proposed.Method: Chaotic synchronization is used for the key management, the diffusion stage is made by means of ergodic sequences generated from the numerical solution of the Lorenz’s attractor and the permutation stage is accomplished with the wave line technique.Results: The proposed algorithm was tested using a set of gray-scale images obtaining suitable performance in segurity and speed, the pixel correlation is almost null and the entropy is similar to that presented in recent works with the same approach.Conclusions: Chaotic methods are an alternative to improve the security levels in the cryptography of images due to their properties of unpredictability and sensitivity to the initial conditions. For future work the approach presented could be applied to the encryption of color images and using different chaotic attractors.Contexto: Con el creciente volumen de  información generada en tiempo real, nuevos mecanismos son necesarios para garantizar su seguridad, evitando el acceso a personas no autorizadas. Los métodos convencionales de criptografía no son apropiados para imágenes por su debilidad a ataques estadísticos, debido a la fuerte correlación entre píxeles adyacentes y el análisis de los histogramas de gamas de colores, lo que puede ayudar a identificarlos dentro de la imagen; con este objetivo en mente, se propone un algoritmo para el cifrado de imágenes utilizando atractores caóticos.Método: La sincronización caótica se utiliza para la gestión de la clave, la etapa de difusión se realiza mediante secuencias ergódicas generadas a partir de la solución numérica del atractor de Lorenz y la etapa de permutación se realiza con la técnica de línea de onda.Resultados: Se probó el algoritmo propuesto utilizando un conjunto de imágenes en escala de grises, obteniendo un desempeño adecuado en seguridad y velocidad, la correlación de píxeles es casi nula y la entropía es similar a la presentada en trabajos recientes con el mismo enfoque.Conclusiones: Los métodos caóticos son una buena alternativa para mejorar los niveles de seguridad en la criptografía de imágenes debido a sus propiedades de imprevisibilidad y sensibilidad a las condiciones iniciales. Para trabajos futuros el enfoque presentado podría aplicarse a la encriptación de imágenes a color y utilizando diferentes atractores caóticos

Modelo de encriptación simétrica basada en atractores caóticos

Context: the increase in the processing capacity of machines and developments in combinatorial search algorithms reduces the time required to decipher the information fraudulently. Bear in mind this, there is a need to generate new ways of encoding information for secure transmission.Method: in this paper a symmetrical and extensible model for digital communications encryption is presented, taking advantage of the chaos generated by nonlinear dynamic systems.Results: the developed model proved to encrypt messages in time synchronization, encryption and decryption less than 1 ms with an entropy higher than 6 using the Rössler attractor for its implementation.Conclusions: the algorithm is presented as an alternative to traditional algorithms demonstrating greater efficiency in the management of computing resources and raises the groundwork for continuing their study on the interested academic community due to the variety of dynamical systems nonlinear.Contexto: El aumento en la capacidad de procesamiento de las máquinas y los desarrollos en los algoritmos de búsqueda combinatoria disminuyen el tiempo necesario para descifrar fraudulentamente la información; por esta razón se plantea la necesidad de generar nuevas formas de codificar la  información para su transmisión segura.Método: En este artículo se presenta un modelo de encriptación simétrico extensible para comunicaciones digitales, aprovechando el caos generado por sistemas dinámicos no lineales.  Resultados: El modelo desarrollado demostró estar en la capacidad de encriptar mensajes en tiempos de sincronización, encriptación y desencriptación inferiores a 1 ms con una entropía superior a 6 usando el atractor de Rossler para su implementación.Conclusiones: El algoritmo se presenta como una alternativa a los algoritmos tradicionales de combinatoria demostrando una mayor eficiencia en la gestión de recursos computacionales y plantea las bases para su continuar con su estudio en la comunidad académica interesada, debido a la variedad de los sistemas dinámicos no lineales.

Unusual winter Saharan dust intrusions at Northwest Spain: Air quality, radiative and health impacts

[EN] Saharan air masses can transport high amounts of mineral dust particles and biological material to the Iberian Peninsula. During winter, this kind of events is not very frequent and usually does not reach the northwest of the Peninsula. However, between 21 and 22 February 2016 and between 22 and 23 February 2017, two exceptional events were registered in León (Spain), which severely affected air quality. An integrative approach including: i) typical synoptic conditions; ii) aerosol chemical composition; iii) particle size distributions; iv) pollen concentration; v) aerosol optical depth (AOD); vi) radiative forcing and vii) estimation of the impact of aerosols in the respiratory tract, was carried out. In the global characterization of these events, the exceedance of the PM10 daily limit value, an increase in the coarse mode and a rise in the iron concentration were observed. On the 2016 event, an AOD and extinction-related Ångström exponent clearly characteristic of desert aerosol (1.1 and 0.05, respectively) were registered. Furthermore, pollen grains not typical of flowering plants in this period were identified. The chemical analysis of the aerosol from the 2017 event allowed us to confirm the presence of the main elements associated with mineral sources (aluminum, calcium, and silica concentrations). An increase in the SO42−, NO3− and Cl− concentrations during the Saharan dust intrusion was also noted. However, in this event, there was no presence of atypical pollen types. The estimated dust radiative forcing traduced a cooling effect for surface and atmosphere during both events, corroborated by trends of radiative flux measurements. The estimated impact on the respiratory tract regions of the high levels of particulate matter during both Saharan dust intrusions showed high levels for the respirable fractionSIThis study was partially supported by the Spanish Ministry of Economy and Competitiveness (Grant TEC2014-57821-R), the University of León (Programa Propio 2015/00054/001 and 2018/00203/001) and the AERORAIN project (Ministry of Economy and Competitiveness, Grant CGL2014-52556-R, co-financed with European FEDER funds). F. Oduber acknowledges the grant BES-2015-074473 from the Spanish Ministry of Economy and Competitiveness. C. Blanco-Alegre acknowledges the grant FPU16-05764 from the Ministry of Education, Culture and Sports, Spain. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and/or READY website (http://www.ready.noaa.gov) used in this study. The authors would also like to express their gratitude to the Naval Research Laboratory for providing the NAAP aerosol map and NASA for the satellite image used in the graphical abstract. The data from the MAPAMA network are property of the Office for Quality and Environmental Evaluation (DGCEA, in its Spanish acronym), belonging to the Ministry of Ecologic Transition. The data were supplied as a result of an agreement between the Spanish Ministry of Agriculture, Food and the Environment and the Scientific Research Council for sponsoring studies related to air pollution by particulate matter and metals in Spain. We thank AERONET network and specially Victoria E. Cachorro Revilla and Carlos Toledano for establishing and maintaining the Valladolid AERONET site used in this investigation. We also thank to Philippe Dubuisson for allowing the use of GAME model, as well as the Laboratoire d'Optique Atmosphérique (University of Lille

Recommendations for treatment with recombinant human growth hormone in pediatric patients in Colombia

En Colombia, actualmente no existen parámetros claros para el diagnóstico de pacientes con talla baja, ni sobre el tratamiento de esta población con hormona de crecimiento recombinante humana (somatropina), lo cual se ve favorecido por la diversidad de programas de formación de profesionales en endocrinología pediátrica. En respuesta a esta problemática se realizó el primer acuerdo colombiano de expertos en talla baja liderado por la Asociación Colegio Colombiana de Endocrinología Pediátrica (ACCEP); este trabajo contó con la participación y el aval de expertos clínicos de importantes instituciones de salud públicas y privadas del país, además de expertos metodológicos del instituto Keralty, quienes garantizaron la estandarización del uso de la somatropina. Después de realizar una minuciosa revisión de la literatura, se propone la unificación de definiciones, un algoritmo diagnóstico, los parámetros de referencia de las pruebas bioquímicas y dinámicas, una descripción de las consideraciones de uso de la somatropina para el tratamiento de las patologías con aprobación por la entidad regulatoria de medicamentos y alimentos en Colombia y, por último, un formato de consentimiento informado y de ficha técnica del medicamento.In Colombia there are no guidelines for diagnosis and management of patients with short stature and for the use of recombinanthuman growth hormone, mainly caused by the diversity of training centers in pediatric endocrinology. In response to this situation,the Asociación Colegio Colombiana de Endocrinología Pediátrica leds the first colombian short stature expert committee in order tostandardize the use of human recombinant growth hormone. This work had the participation and endorsement of a consortium ofclinical experts representing the Sociedad Colombiana de Pediatría, Secretaría Distrital de Salud de Bogotá- Subred Integrada deServicios de Salud Suroccidente, Fundación Universitaria Sanitas, Universidad de los Andes and some public and private healthinstitutions in the country, in addition to the participation of methodological experts from the Instituto Global de Excelencia ClínicaKeralty. By reviewing the literature and with the best available evidence, we proposed to unify definitions, a diagnostic algorithm,biochemical and dynamic tests with their reference parameters, a description of the considerations about growth hormone use amongthe indications approved by regulatory agency for medications and food in Colombia and finally a proposal for an informed consentand a medication fact sheet available for parents and patients.https://orcid.org/0000-0002-7856-7213https://orcid.org/0000-0003-2241-7854Revista Nacional - Indexad

Solución débil de un problema hiperbólico de tipo escalar

In this expository paper we present a weak solution for a hyperbolic equation. The method of compensated compactness is usedEn este artículo se encuentra una solución débil para una ecuación hiperbólica de tipo escalar utilizando el método de compacidad compensad

Encryption Algorithm for color Images based on Chaotic Systems

Context: Taking advantage of the foundations of the theory of non-linear dynamic systems, we propose an encryption model for color images based on chaotic systems, which satisfies security standards in accordance with the challenges faced by society. Method: A symmetrical algorithm is proposed using Arnold's chaotic Cat system for permutation and for diffusion Chen's hyperchaotic system or Lorenz's hyperchaotic system, a parallel programming in implementation is used to reduce execution times. Results:Performance metrics are applied to evaluate the security of the proposed cryptographic model, finding that the indicators obtained are framed within those published in recent articles that address the problem of security through chaos. Conclusions: The results obtained confirm that the use of chaos theory as a tool for strengthening security schemes in communications is a good alternative, particularly when referring to image transfer. Contexto: Aprovechando los fundamentos de la teoría de sistemas dinámicos no lineales se propone un modelo de encriptación para imágenes a color basado en sistemas caóticos, que satisface estándares de seguridad acordes con los desafíos a que se enfrenta la sociedad. Método:  Se propone un algoritmo simétrico utilizando el sistema caótico Cat de Arnold para la permutación y para la difusión el sistema hipercaótico de Chen o el sistema hipercaótico de Lorenz, en la implementación se utiliza programación paralela para reducir los tiempos de ejecución. Resultados: Se aplican métricas de desempeño para evaluar la seguridad del modelo criptográfico propuesto, encontrando que los indicadores obtenidos se enmarcan dentro de los publicados en artículos recientes que  abordan el problema de la seguridad a través del caos. Conclusiones: Se aplican métricas de desempeño para evaluar la seguridad del modelo criptográfico propuesto, encontrando que los indicadores obtenidos se enmarcan dentro de los publicados en artículos recientes que  abordan el problema de la seguridad a través del caos