Fluid net models: from behavioral properties to structural objects

Increasing the production in manufacturing systems is one of the main demands in modern systems. The naive approach that this goal can be achieved when more or faster resources are used is not always valid. In fact, the complex interactions among system’s elements may lead to paradoxical behaviors; for example, using faster machines could reduce the equilibrium throughput (number of part fabricated per unit time in steady state) of the system, or even worse, block all system activities, reducing it to zero. This work leverages the concepts about fluidization and analysis techniques used in Timed Continuous Petri nets (TCPN) presented in earlier works to study the behavior of the equilibrium throughput when more/faster machines are used. Herein, we illustrate how discontinuities induced bifurcations of the equilibrium throughput are due to the existence of paths that can increase/decrease the marking of certain subnets. In particular, if paths gaining/losing tokens are fired without a particular balance, then the equilibrium throughput exhibits discontinuities since the equilibrium marking loses hyperbolicity. Moreover, these discontinuities imply other undesired throughput behaviors; for example, the existence of non-monotonicities of the equilibrium throughput (when more/faster resources are used in the system, its equilibrium throughput is reduced). The discontinuities together with a homothecy property are used to explain non-monotonicities in the equilibrium throughput. A relevant aspect is that these undesired system behaviors appear when the net has structural objects named problematic configurations that are associated with certain subnets in which there are no P-semiflows. Although the number of these configurations increase exponentially in the size of the net, some reduction rules are introduced to remove configurations, while the problematic ones are kept (or can be recovered) in the reduced net. This saves computation time in the analysis and, more importantly, provides useful insights about the root of undesired behaviors. This work focus on systems that can be modeled with fluid (or continuous) mono T-semiflow Timed Continuous Petri nets. Even if under certain constraints, they are capable of capturing many characteristics of modern systems, such as interleaving of cooperation and competition

Resolución por Skype de una tarea de visualización cooperativa por una pareja de estudiantes de talento

En este trabajo analizamos la transmisión de información entre dos estudiantes de alta capacidad matemática mientras resuelven, a través de videoconferencia, una tarea cooperativa de visualización. Las categorías que más afloraron en el análisis del discurso fueron informar, demandar información, sugerir, parafrasear y confirmar. Los indicadores que más manifestaron fueron validación, ampliación y paráfrasis. Los estudiantes manifestaron características del talento matemático como un alto compromiso con la tarea, a pesar de su dificultad, y buena capacidad para organizar los datos y para desarrollar estrategias eficientes de resolución

Exploitation of nuclear and cytoplasm variability in Hordeum chilense for wheat breeding

Hordeum chilense Roem. et Schultz. is a diploid wild barley native to Chile and Argentina. The high crossability of this species with other members of the Triticeae tribe promoted the development of the new species × Tritordeum Ascherson et Graebner. Hexaploid tritordeum was developed from the hybrid derived from the cross between H. chilense (used as female parent) and durum wheat. The interest of H. chilense is based on the presence of traits potentially useful for wheat breeding, including high endosperm carotenoid content, septoria tritici blotch resistance and abiotic stress tolerance. Besides, the variability at cytoplasm level is also important in this species. The development of common wheat-H. chilense alloplasmic lines (nucleus from wheat and cytoplasm from H. chilense) results in fertile or male sterile genotypes, depending on the accession donating the cytoplasm. Furthermore, these alloplasmic lines constitute an ideal system for deepening our knowledge on nuclear-cytoplasm interactions. In conclusion, H. chilense is an interesting source of variability for wheat breeding. © 2011 NIAB.Our work in this area is supported by grants (to S. G. A.) AGL2008-03720, and P09-AGR-4817 from Spanish Ministry of Science and Innovation, Junta de Andalucía and FEDER. C. R.-S. acknowledges financial support from CSIC (JAE-Doc program).Peer Reviewe

Material and immaterial forms of miracle appropriation among the neogranadina population, 16th, 17th and 18th centuries

El artículo analiza las formas de producción, apropiación y circulación del milagro entre la población del Nuevo Reino de Granada, durante los siglos XVI, XVII y XVIII. Se recurrió a la concepción del milagro como condición de posibilidad de “lo maravilloso cristiano”, según relaciones o diarios de viaje escritos por clérigos de diferentes órdenes regulares y seculares que transitaron por el territorio con fines misionales, realizándose una tipología de los hechos identificados. La metodología se orientó desde una mirada popular del milagroo indagándose sobre los procesos de producción de santos locales, la retórica eclesiástica sobre la asistencia de santos en la enfermedad, la configuración de expresiones materiales e inmateriales de gratitud y los fenómenos de circulación y difusión del milagro en el centro del territorio mencionado. Además se identificaron cuatro categorías de milagros -de una imagen sobre sí, de asistencia, físicos y taumatúrgicos- y se agruparon como impersonales, individuales o colectivos. The paper analyzes the forms of production, appropriation and circulation of miracles among the population of Nueva Granada, in the sixteenth, seventeenth and eighteenth centuries. The concept of miracle as a condition of possibility of “the Christian as wonderful”, according to relations or travel diaries written by clerics of different regular and secular orders, who travelled through the territory with missional purposes, was used to draw a typology of the facts identified. The methodology is oriented by a popular look of miracles and studies the production of local saints as a process, the ecclesiastical rhetoric informing about the assistance of these saints in disease, the configuration of tangible and intangible expressions of gratitude and the phenomena of miracle circulation and dissemination at the center of the mentioned territory. Four categories of miracles were identified –of an image on itself, assistance, physical and thaumaturgic- and were classified as impersonal, individual or collective.&nbsp

A Qué Te Enfrentas Cuando Emprendes

"Puerta de Sol" is an ecotourism project. This tourist unit will be located in the community of Miguel Colorado in the municipality of Champotón Campeche. The project was developed by applying the methodology for Environmentally Planned Tourism (EPT). The author of this methodology is named Jorge Chavez de la Peña. Chavez is a writer recognized for his contributions in the project of the monarch butterfly in the community El Capulín. The author took as a specific methodological basis the Gulf of California Ecotourism Cyber Atlas, elaborated for the SEMARNAT. The project "Puerta de Sol" is to build ecological cabins. In order to develop this project, renewable materials were used. These materials are used to the everyday activities of the community and as a fundamental part of their economic development

El movimiento de acceso abierto a la ciencia: referentes globales, regionales y locales

Durante el siglo xx la ciencia en el mundo experimentó un crecimiento sin antecedentes en la historia, en términos de su producción (Artola & Sánchez Ron, 2012). La masa creciente de fuentes primarias como artículos científicos, libros, tesis doctorales y patentes, entre otros, obligó al desarrollo de fuentes secundarias, que inicialmente fueron libros de resúmenes en papel (como los Psychological Abstracts de la American Psychological Association) y posteriormente bases de datos electrónicas (como la secuencia tecnológica de PsycLIT, PsycINFO y PsycNET, también de la apa)

Competencia cultural y artística, autopercepción del alumnado de sexto de primaria

Somos conscientes de la importancia que tiene el desarrollo de la Competencia Cultural y Artística para el fomento del pensamiento crítico, la creatividad, la expresión y el reconocimiento de la diversidad cultural, la sensibilidad hacia el arte, etc., para el desarrollo integral de la futura ciudadanía. Por ello, en el presente estudio hemos pretendido conocer la autopercepción que tiene el alumnado de sexto curso de Educación Primaria de Córdoba capital y provincia con respecto a su propio nivel en el desarrollo de esta competencia. Se trata de una investigación descriptiva y transversal donde se ha utilizado el método de encuesta y en la que se han tenido en cuenta variables como el género, el tipo de centro educativo (público o concertado) o la práctica de actividades extraescolares relacionadas con la música y la danza. Los resultados muestran la influencia de estas variables en la autopercepción del alumnado con respecto al nivel de adquisición de esta competenciaWe recognize the importance of the development of cultural awareness and expression competence in order to encourage critical thinking, creativity, expression and recognition of cultural diversity, sensitivity towards art, and so on, to get the integral development of the future citizenship. Therefore, in this study we sought to know the self-perception that students in the sixth year of primary education in Córdoba city and province have about their own level of this competence. This is a descriptive and cross-sectional research that it has used the survey method and analyzed different variables such as gender, type of school (public or private) or practice of extracurricular activities related to music and dance. The results show the influence of these variables on the self-perception of students about the level of this competenc