Second order parameter-uniform convergence for a finite difference method for a partially singularly perturbed linear parabolic system

A linear system of $n$ second order differential equations of parabolic reaction-diffusion type with initial and boundary conditions is considered. The first $k$ equations are singularly perturbed. Each of the leading terms of the first $m$ equations, $mleq k$, is multiplied by a small positive parameter and these parameters are assumed to be distinct. The leading terms of the next $k-m$ equations are multiplied by the same perturbation parameter $varepsilon_m$. Since the components of the solution exhibit overlapping layers, Shishkin piecewise-uniform meshes are introduced, which are used in conjunction with a classical finite difference discretisation, to construct a numerical method for solving this problem. It is proved that in the maximum norm the numerical approximations obtained with this method are first order convergent in time and essentially second order convergent in the space variable, uniformly with respect to all of the parameters

Second order parameter-uniform convergence for a finite difference method for a partially singularly perturbed linear parabolic system

A linear system of $n$ second order differential equations of parabolic reaction-diffusion type with initial and boundary conditions is considered. The first $k$ equations are singularly perturbed. Each of the leading terms of the first $m$ equations, $mleq k$, is multiplied by a small positive parameter and these parameters are assumed to be distinct. The leading terms of the next $k-m$ equations are multiplied by the same perturbation parameter $varepsilon_m$. Since the components of the solution exhibit overlapping layers, Shishkin piecewise-uniform meshes are introduced, which are used in conjunction with a classical finite difference discretisation, to construct a numerical method for solving this problem. It is proved that in the maximum norm the numerical approximations obtained with this method are first order convergent in time and essentially second order convergent in the space variable, uniformly with respect to all of the parameters

Empresas recuperadas por trabalhadores como política pública: estudo de caso sobre a reigão de Misiones - Argentina

Dissertação apresentada ao Programa de Pós-Graduação em Políticas Públicas e Desenvolvimento da Universidade Federal da Integração Latino-Americana, como requisito parcial à obtenção do título de Mestre em Políticas Públicas e Desenvolvimento. Orientadora: Profa. Dra. Cláudia Lúcia Bisaggio SoaresEm meio à crise econômica argentina com ápice no ano de 2001, cresceu o fenômeno da recuperação de empresas em processo de falência pelos próprios trabalhadores e este fato ganhou destaque por apresentar uma alternativa de continuidade das atividades comerciais em meio a um cenário de desemprego. Na sequência desses acontecimentos, a Economia Solidária e suas vertentes foram adotadas como discurso de governo no período do kirchnerismo, que no ano de 2011 trouxe significativa mudança às Empresas Recuperadas por Trabalhadores (ERT), com a promulgação da Ley n. 26.684, que permitiu, na teoria, a compensação das dívidas laborais para adjudicação dos meios de produção em favor dos trabalhadores. Nesse trabalho se utilizou o caso brasileiro e suas especificidades para traçar um paralelo com a trajetória da Economia Solidária enquanto política pública na Argentina e o que os atores envolvidos compreenderam ser necessário para sua institucionalização e efetivação nesses países. Argumentouse que a política pública não se restringe a uma alteração legal, mas requer ações complementares e estruturais para sua implementação. Nesse sentido, o estudo de caso foi fundamental para compreensão sobre se, apesar das críticas, as ERT locais conseguiram tecer algum arranjo que fosse capaz de representar o resultado de uma política pública de criação e manutenção desse fenômeno, e de onde veio o apoio para esse fim. Para tanto, realizou-se uma coleta de dados em duas ERT localizadas na província de Misiones-Argentina, e em quatro instituições públicas que prestam assistência a essas empresas. Concluiu-se que, apesar de medidas importantes, como a alteração legislativa, essas não foram suficientes para configurar uma política pública de fomento às ERT na Argentina.Amid of the argentine economic crisis with a peak in the year 2001, the phenomenon of recovery of companies in bankruptcy by the workers themselves grew, and this fact was highlighted by presenting an alternative of continuity of commercial activities in the midst of an unemployment scenario. In sequence of these events, Solidarity Economy and its aspects were adopted as a government discourse in the Kirchnerism period, which in 2011 brought a significant change to the Companies Recovered by Workers, with the promulgation of Law n. 26,684, which in theory allowed the compensation of labor debts for the adjudication of the means of production in favor of the workers. In this work the Brazilian case and its specificities were used to draw a parallel with the Solidarity Economy trajectory as public policy in Argentina and what the involved actors understood to be necessary for their institutionalization and effectiveness in these countries. It was argued that public policy is not restricted to a legal change, but requires complementary and structural actions for its implementation. In this sense, the case study was fundamental to understand if, despite the criticisms, the local Companies Recovered by Workers managed to weave some arrangement that could represent the result of a public policy of creation and maintenance of this phenomenon, and from where came the support for this purpose. For that, a data collection was made in two Companies Recovered by Workers located in the province of Misiones-Argentina, and in four public institutions that provide assistance to these companies. It was concluded that, despite important measures, such as the legislative amendment, these were not enough to set up a public policy to foment the Recovered Companies by Workers in ArgentinaEn medio de la crisis económica argentina con ápice en el año 2001, creció el fenómeno de la recuperación de empresas en proceso de quiebra por los propios trabajadores y este hecho ganó destaque por presentar una alternativa de continuidad de las actividades comerciales en medio de un escenario de desempleo. En consecuencia de estos acontecimientos, se adoptaron la Economía Solidaria y sus vertientes como discurso de gobierno en el período del kirchnerismo, que en el año 2011 trae un significativo cambio a las Empresas Recuperadas por Trabajadores (ERT), con la promulgación de la Ley n. 26.684, que permitió, en teoría, la compensación de las deudas laborales para la adjudicación de los medios de producción en favor de los trabajadores. En ese trabajo se utilizó el caso brasileño y sus especificidades para trazar un paralelo con la trayectoria de la Economía Solidaria como política pública en Argentina y lo que los actores implicados comprendieron que era necesario para su institucionalización y efectividad en esos países. Se argumentó que la política pública no se restringe a un cambio legal, pero requiere acciones complementarias y estructurales para su implementación. En este sentido, el estudio de caso fue fundamental para comprender si, a pesar de las críticas, las ERT locales lograron hacer algún arreglo que fuera capaz de representar el resultado de una política pública de creación y mantenimiento de ese fenómeno, y de donde vino el apoyo para este fin. Por lo tanto, se realizó una recolección de datos en dos ERT ubicadas en la provincia de Misiones-Argentina, y en cuatro instituciones públicas que prestan asistencia a esas empresas. Se concluyó que, a pesar de medidas importantes, como la modificación legislativa, éstas no fueron suficientes para configurar una política pública de fomento a las ERT en ArgentinaObservação: o autor obteve afastamento remunerado concedido pelo Instituto Federal do Paraná em parte do curso de mestrado em Políticas Públicas e Desenvolvimento como forma de incentivo à qualificação do servidor

Electronic Energy Relaxation in a Photoexcited Fully Fused Edge-Sharing Carbon Nanobelt

Carbon nanobelts are cylindrical molecules composed of fully fused edge-sharing arene rings. Because of their aesthetically appealing structures, they acquire unusual optoelectronic properties that are potentially suitable for a range of applications in nanoelectronics and photonics. Nevertheless, the very limited success of their synthesis has led to their photophysical properties remaining largely unknown. Compared to that of carbon nanorings (arenes linked by single bonds), the strong structural rigidity of nanobelts prevents significant deformations away from the original high-symmetry conformation and, therefore, impacts their photophysical properties. Herein, we study the photoinduced dynamics of a successfully synthesized belt segment of (6,6)CNT (carbon nanotube). Modeling this process with nonadiabatic excited state molecular dynamics simulations uncovers the critical role played by the changes in excited state wave function localization on the different types of carbon atoms. This allows a detailed description of the excited state dynamics and spatial exciton evolution throughout the nanobelt scaffold. Our results provide detailed information about the excited state electronic properties and internal conversion rates that is potentially useful for designing nanobelts for nanoelectronic and photonic applications.Fil: Freixas Lemus, Victor Manuel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Oldani, Andres Nicolas. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Franklin Mergarejo, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Tretiak, S.. Los Alamos National High Magnetic Field Laboratory; Estados UnidosFil: Fernández Alberti, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin

X-ray phase contrast imaging of biological specimens with tabletop synchrotron radiation

Since their discovery in 1896, x-rays have had a profound impact on science, medicine and technology. Here we show that the x-rays from a novel tabletop source of bright coherent synchrotron radiation can be applied to phase contrast imaging of biological specimens, yielding superior image quality and avoiding the need for scarce or expensive conventional sources

Chemical weed control in Dracaena fragans cv. massangeana in Alajuela, Costa Rica

En dos localidades del Valle Central Occidental, de Costa Rica: en Buenos Aires y Zaragoza de Palmares, Alajuela, ubicadas a 1000 msnm, precipitación anual de 1142 mm y temperatura de 23ºC, se realizaron dos experimentos con herbicidas preemergentes en Dracaena fragans cv. massangeana. El primer experimento se realizó en Buenos Aires, en los meses de agosto a noviembre de 1987, en una plantación de un año de edad, sembrada a 1 x 0,75 m. Los tratamientos evaluados fueron: oxifluorfén + terbutilazina (0,5 + 1,5 kg/ha); oxifluorfén + terbutrina (0,5 + 1,5 kg/ha); oxifluorfén + metribuzina (0,5 + 0,4 kg/ha); oxifluorfén + atrazina (0,5 + 1,5 kg/ha); alaclor + metribuzina (1,5 + 0,4 kg/ha); alaclor + terbutrina (1,5 + 1,5 kg/ha); alaclor + ametrina (1,5 + 1,5 kg/ha); y diurón (1,0 kg/ha). El segundo experimento se realizó en Zaragoza, en los meses de setiembre a noviembre de 1988, en una plantación de 1,5 años, sembrada a 1 x 0,75 m. Los tratamientos fueron: oxifluorfén (0,6kg/ha); oxifluorfén + terbutilazina (0,6 + 1,75 kg/ha); alaclor + terbutilazina (1,75 + 1,75 kg/ha); alaclor + atrazina (1,75 + 1,75 kg/ha); alaclor + oxifluorfén (1,75 + 0,6 kg/ha) y diurón + atrazina (1,5 + 1,75 kg/ha). Se incluyeron, en ambos experimentos, dos testigos, uno de libre competencia y otro con una deshierba mecánica cada 30 días después de la aplicación. Con ningún tratamiento ocurrió fitotoxicidad en el cultivo. El mejor control de malezas gramíneas se obtuvo cuando las mezclas contenían oxifluorfén. Se logró comprobar que las prácticas culturales y la morfología de las plantas en conjución con la densidad de siembra, disminuyen la densidad y agresividad de las malezas, a medida que el follaje del cultivo crece y forma un microclima desfavorable, para aquellas malezas que crecen bajo su copa.Two trials were conducted with pre-emergent herbicides in Dracaena fragans cv. massangeana, at two localities of the Western Central Plateau, located at 1000 m.a.s.l., with an annual rainfal of 1142 mm and a temperature of 23ºC. The first test was conducted from August to November of 1987 in a year old plantation, with a planting distance of 1 x 0.75 m. The evaluated treatments were: oxyflurofen + terbutylazine at (0.5 + 1.5 kg/ha), oxyfluorfen + terbutryn at (0.5 + 1.5 kg/ha), oxyfluorfen + metribuzin at (0.5 + 0.4 kg/ha), oxyfluorfen + atrazine at (0.5 + 1.5 kg/ha), alachlor + metribuzin at (1.5 + 0.4 kg/ha), alaclor + terbutryn at (1.5 + 1.5 kg/ha), alaclor + ametryn at (1.5 + 1.5 kg/ha) and diuron at (1.0 kg/ha). The second trial was conducted in Zaragoza, from September to November, 1988, in a one and one-half year's old plantation, with the same planting distance. The treatments were: oxyfluorfen at (0.6 kg/ha), oxyfluorfen + terbutylazine at (0.6 + 1.75 kg/ha), alachlor + terbutylazine at (1.75 + 1.75 kg/ha), alaclor + atrazine at (1.75 + 1.75 kg/ha), alachlor + oxyfluorfen at (1.75 + 0.6 kg/ha) and diuron + atrazine al (1.50 + 1.75 kg/ha). Two controls were included in both experiments, one unweeded and the other one was mechanically weeded every 30 days after the application. No phytotoxicity symptoms were observed in any of the treatments. The best gramineous control was obtained when oxyfluorfen was included in the mixture. It was proved that the cultural practices and the plant morphology, joined to the plant density, reduced the population and aggresiveness of the weeds. As the crop's foliage grows, it produces an unfavorable microclimate for those weeds growing under its shade.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Análisis de las cirugías cardíacas y mortalidad operatoria en el Instituto Nacional Cardiovascular durante el 2022

Objective. To describe cardiac surgeries, their approaches, and determine operative mortality according to the type of surgery and the main complications recorded within 30 days postoperatively, performed at the National Cardiovascular Institute of Peru. Materials and methods. A descriptive study was conducted on all patients over 18 years of age who underwent cardiovascular surgery at the National Cardiovascular Institute “Carlos Alberto Peschiera Carrillo”. Results. During the year 2022, a total of 503 cardiac surgeries were performed. Of the patients undergoing surgery, 63.6% (320) were males. Isolated valvular surgery, primarily aortic or mitral valve replacement, was the most frequent surgical procedure, with 136 surgeries (27.0%). This was followed by myocardial revascularization surgery with 110 procedures (21.9%). Throughout the year, there were 23 deaths, resulting in an overall mortality rate of 4.5%. The mortality rate for elective surgeries was 2.8%, while for emergency surgeries, it was 14.3%. The most common complication was paroxysmal atrial fibrillation (14.0%), followed by surgical site infection with 52 cases (10.3%). Conclusions. Valvular surgery, whether isolated or combined with other procedures, was the most frequently performed. The obtained mortality rate is considered acceptable for a reference center.Objetivo. Describir las cirugías cardíacas, su abordaje y determinar la mortalidad operatoria según el tipo de cirugía y las principales complicaciones registradas hasta los 30 días del posoperatorio realizadas en el Instituto Nacional Cardiovascular de Perú. Materiales y métodos. Se llevó a cabo un estudio descriptivo en todos los pacientes mayores de 18 años que fueron sometidos a cirugía cardiovascular en el Instituto Nacional Cardiovascular «Carlos Alberto Peschiera Carrillo». Resultados. Durante el año 2022 se realizaron 503 cirugías cardíacas. De los pacientes intervenidos, el 63,6% (320) fueron varones. La cirugía valvular aislada, principalmente el reemplazo de la válvula aórtica o mitral, fue el procedimiento quirúrgico más frecuente, con 136 cirugías (27,0%). Le siguió la cirugía de revascularización de miocardio con 110 procedimientos (21,9%). A lo largo del año se registraron 23 fallecimientos, lo que resultó en una mortalidad general del 4,5%. La mortalidad en cirugías electivas fue del 2,8%, mientras que en cirugías de emergencia fue del 14,3%. La complicación más común fue la fibrilación auricular paroxística (14,0%), seguida de la infección del sitio quirúrgico con 52 casos (10,3%). Conclusiones. La cirugía valvular, ya sea aislada o en combinación con otros procedimientos, fue realizada con más frecuencia. La tasa de mortalidad obtenida se considera aceptable para un centro de referencia

Incidencia de la Ley Orgánica de Economía Popular y Solidaria y del Sector Financiero Popular y Solidario frente a la sostenibilidad y competitividad de las cooperativas de ahorro y crédito reguladas por el MIES – IEPS Chimborazo en la ciudad de Riobamba, período 2012

El presente estudio es el de analizar el impacto de la Ley de Economía Popular y Soli-daria y del Sector Financiero Popular y Solidario en la Sostenibilidad y Competitividad de las Cooperativas de Ahorro y Crédito Reguladas por el MIES – IEPS en la ciudad de Riobamba. La Ley Orgánica de la Economía Popular y Solidaria y del Sector Financiero Popular y Solidario regula el marco jurídico de las organizaciones populares y solidarias, muchas de ellas de conformación indígena y campesina, que se dedican a procesos de produc-ción, intercambio, comercialización, financiamiento y consumo agrícola. La presente Ley tiene por potenciar las prácticas de la economía popular y solidaria que se desarrollan en las comunas, comunidades, pueblos y nacionalidades, y en sus unida-des económicas productivas para alcanzar el Sumak Kawsay. Mediante al estudio realizado se puede identificar claramente que unas cooperativas mantienen más pasivos que activos, situación que debe entrar en regulación de acuerdo como indica la ley, y no es más que el efecto de no conocer el sistema financiero y su equilibrio. En base a las exhaustivas investigaciones realizadas la recomendación es que las cooperativas deberán convertirse en instituciones generadoras de proyectos encami-nados en la ayuda del desarrollo económico social de cada uno de sus asociados y a los sectores que atiendan con sus productos financieros, para con ello cumplir una de los requisitos solicitados por la Superintendencia de Economía Popular y Solidaria que es el Balance Social.The present research is to analyze the impact of Popular and Solidarity Economy Law in popular financial sector in the sustainability and competitiveness of savings and credit co-operatives regulated by MIES in Riobamba city. The Popular Organic and Solidarity Economy Law and the Financial Popular and Solidary Sector regulate the legal framework of the popular and solidary organizations, many of them of indigenous and rural conformation, engaged in processes of production, exchange, commercialization, finance and agricultural consumption. The present Law tries to promote the practices of the popular and solidarity economy that develop in the communes, communities, and nationalities, and in their productive econom-ic units to achieve Sumak Kawsay. Through this research was possible to identify clearly that some cooperatives have more liabilities than assets, situation that should enter under regulation as required by law, and is nothing more than ignorance of financial system and balance. Based on the extensive research the recommendation is that cooperatives should become in generating institutions support projects aimed at economic development of individual so-cial partners and sectors that meet their financial products, to thereby fulfilling one of re-quirements by the Superintendence of Popular and Solidarity Economy that is the social balance

Effect of dopant and heat treatment on the microstructure and mechanical properties of Nickel-Aluminum bronze.

The effect of dopant and heat treatment on the microstructure and mechanical properties of Nickel-aluminum bronze (Cu-10%Al-5%Ni-5%Fe-x%Mo) were extensively investigated. The cast samples were heat treated through different processes, including solutionizing, quenching, and aging; their microstructures were examined using an optical microscope, scanning electron microscopy and energy dispersive spectroscopy analysis and their mechanical properties determined. The microstructure of the as-cast samples consisted of Cu-rich ‘α-phase, ‘κ-phases and small volume fraction of β'-phase while solutionizing transformed the β'-phase to a homogenous β-phase, α, and κ phases. Quenching transformed all β phase to β'-phase, however, aging the alloy precipitated fine dispersive strengthening κ-phases from the quenched microstructure. The results of the mechanical tests showed that the aged samples had improved excellent mechanical properties compared to the as-cast samples. Compared to the base alloy, the tensile strength and hardness of the aged 2% Mo sample increased by 58% and 55%, respectively while the impact strength and elongation decreased by 27% and 22%, respectively. Similarly, the tensile strength and hardness of the aged 3% Mo sample increased by 44% and 49%, respectively, while the impact strength and % elongation decreased by 23.9% and 24.9%, respectively