La factorización de polinomios. Una experiencia docente

Tradicionalmente, el aprendizaje de la factorización de polinomios ha sido uno de los tópicos más problemáticos para nuestros alumnos y alumnas, debido a la forma de “enseñanza”, basada en reglas o pasos, según el caso de que se trate. Esta dificultad se presenta en los niveles medio y superior (pre cálculo).En nuestra práctica docente y en los materiales impresos que hemos producido, hemos aplicado un enfoque diferente, a partir de los productos notables, los cuales se trabajan previamente mediante la técnica de taller. Se organizan las actividades de aprendizaje de tal forma que los alumnos y las alumnas descubren por sí mismos las propiedades, antes llamadas “reglas” y que eran dadas como un dogma que había que memorizar

Recursos educativos: La integración de la Tecnología para el Desarrollo Humano en Secundaria

Peer Reviewe

A unique way to form a vesicle: aminopeptidase 1 aggregation and its binding to receptor ATG19 for recruitment of autophagic proteins to form a vesicle in the cytoplasm-to-vacuole-targeting pathway in yeast

Title from PDF of title page (University of Missouri--Columbia, viewed on May 30, 2012).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. Per E. StrømhaugVita.Includes bibliographical references.Dissertations, Academic -- University of Missouri--Columbia -- Biological sciences.Ph. D. University of Missouri-Columbia 2011."December 2011"Misfolded protein aggregation causes disease and aging; autophagy counteracts this by eliminating damaged components, enabling cells to survive starvation. The Cytoplasm-to-vacuole-targeting (Cvt) pathway in yeast encompasses the aggregation of the premature form of Aminopeptidase 1 (prApe1) in cytosol, its targeting by its autophagic receptor Atg19, and its sequestration inside a vesicle formed by autophagic proteins for vacuolar transport. The goal of this research was to elucidate the mechanism of prApe1 aggregation and binding to its receptor Atg19, to better understand how selective autophagy takes place and to develop an in vitro assay of autophagy. This study shows that the propeptide of Ape1 is important for aggregation and vesicle formation, it is sufficient for binding to prApe1 and Atg19. Defective aggregation disrupts vacuolar transport, suggesting aggregate shape is important in vesicle formation, while Atg19 and Atg11 binding is not sufficient for vacuolar transport. Ape1 dodecamerization may cluster propeptides into trimeric structures, with sufficient affinity to form propeptide hexamers by binding to other dodecamers, causing aggregation. Furthermore, the N- and C-terminal domains of Atg19 are critical for its correct localization on the surface of aggregates. Atg19 with N- or C-terminal deletions localizes inside aggregates instead, which could interfere with its binding to cytosolic autophagic proteins and cargo for vesicle formation. Meanwhile, the coiled-coil of Atg19 is sufficient for binding to the helix-turn-helix propeptide of prApe1. This study also shows that the mechanism of Atg19 binding to Ape1 aggregates is modified after starvation by the Atg1-Atg13 complex, which plays a key role in autophagy induction and pre-autophagosomal structure (PAS) assembly. A novel in vitro assay was developed, in which prApe1 aggregates and binds Atg19 and Atg8. This could be used as a scaffold for an in vitro assay of autophagosome formation to elucidate the mechanisms of autophagy

Ecomorphology of the African felid ensemble: the role of the skull and postcranium in determining species segregation and assembling history

Morphology of extant felids is regarded as highly conservative. Most previous studies have focussed on skull morphology, so a vacuum exists about morphofunctional variation in postcranium and its role in structuring ensembles of felids in different continents. The African felid ensemble is particularly rich in ecologically specialized felids. We studied the ecomorphology of this ensemble using 31 cranial and 93 postcranial morphometric variables measured in 49 specimens of all 10 African species. We took a multivariate approach controlling for phylogeny, with and without body size correction. Postcranial and skull + postcranial analyses (but not skull-only analyses) allowed for a complete segregation of species in morphospace. Morphofunctional factors segregating species included body size, bite force, zeugopodial lengths and osteological features related to parasagittal leg movement. A general gradient of bodily proportions was recovered: lightly built, long-legged felids with small heads and weak bite forces vs. the opposite. Three loose groups were recognized: small terrestrial felids, mid-to-large sized scansorial felids and specialized Acinonyx jubatus and Leptailurus serval. As predicted from a previous study, the assembling of the African felid ensemble during the Plio-Pleistocene occurred by the arrival of distinct felid lineages that occupied then vacant areas of morphospace, later diversifying in the continent.Fil: Morales, Miriam Mariana. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales E Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Giannini, Norberto Pedro. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentin

Caries y pérdida prematura del primer molar permanente en niños de escuela primaria, y nivel de conocimiento de los padres, en el estado de Vargas, Venezuela.

Introduction: The first permanent molars are the most affected due to age of eruption and their anatomical characteristics. Objective: to determine the prevalence of caries and premature loss of the first permanent molar in a group of grade school children 6 - 12 years of age, and to determine the level of prevention knowledge of the parents, in Vargas state, Venezuela. Materials and Methods: observational study with 182 children between 6 and 12 years old who underwent a clinical evaluation. The parents were asked about their knowledge regarding caries, methods of prevention and chronology of eruption of the child’s first permanent molar. Study was approved by the Bioethics Committee of the Faculty of Dentistry at Universidad Santa María. Results: 6.60% of children presented caries in tooth 16, 6.08% in tooth 26, 24.85% in the tooth 36 and 15.62% in tooth 46. Regarding premature loss, 0.55% had lost tooth 26, 4.95% tooth 36 and 4.40% tooth 46. None presented loss of tooth 16. It was observed that 90.11% of parents had knowledge about dental caries and 44.51% knew how to prevent them. However, only 12.09% knew the age of eruption of the first molar and only 7.69% knew that it has no predecessor. Conclusions: The highest percentage of caries was in tooth 36. The lower molars were the most commonly extracted. The majority of parents demonstrated to have little knowledge about caries and permanent first molars.Introducción: Los primeros molares permanentes son los más afectados debido a la edad de erupción y a sus características anatómicas. Objetivo: determinar la prevalencia de caries y pérdida prematura del primer molar permanente en un grupo escolares de 6 – 12 años y el nivel de conocimiento en prevención de los padres, Estado Vargas, Venezuela. Materiales y Métodos: estudio observacional con 182 niños entre 6 y 12 años a los que se les realizó una evaluación clínica. Se interrogó a los padres sobre el nivel de conocimiento de la caries, métodos de prevención y cronología de erupción del primer molar permanente. Se contó con el aval de Bioética de la Facultad de Odontología de la Universidad Santa María. Resultados: El 6,60% presentó caries en la UD 16, el 6,08% en la UD26, el 24,85% en la UD 36 y el 15,62% en la UD 46. Respecto a la pérdida prematura, el 0,55% había perdido la UD 26, el 4,95% la UD 36 y el 4,40% la UD 46. Ninguno presentó pérdida de la UD 16. Se observó que el 90,11% de los padres tenía conocimiento sobre la caries dental y el 44,51% conocía los medios para prevenirlas. Sin embargo, solo el 12,09% conocía la edad de erupción del primer molar y únicamente el 7,69% sabía que no tiene antecesor. Conclusiones: El mayor porcentaje de caries lo tuvo UD-36. Los molares inferiores fueron los más extraídos. La mayoría de los padres demostró poseer escasos conocimientos sobre caries y primeros molares permanentes

Pleistocene extinction and geographic singularity explain differences in global felid ensemble structure

Extant felids are hyper-carnivorous predators that originated in Asia c. 11 Mya and diversified in 8 distinct lineages, with 41 species surviving to the Recent. These species occupy almost every terrestrial habitat available in the four continental land masses they occupy and exhibit morphological and behavioral specializations to various locomotor styles and hunting modes. Today, distinct felid ensembles inhabit each continent and major biogeographic region. How the differential structuring of these ensembles was generated, and which evolutionary processes shaped these differences across ensembles, are key emerging questions. Using multivariate statistics, we analyzed a large dataset of 31 cranial and 92 postcranial linear variables describing shape and functional proxies of the entire skeleton of extant felids. We statistically demonstrate the existence of nine felid morphotypes at the global scale, whose occurrence is characteristic of different continental or biogeographic ensembles. Phylogenetically explicit analyses show that morphotypes from different felid lineages converged in different continents, but still ensembles remain distinct due to the fact that various morphotypes are missing in several of those ensembles. However, fossil evidence suggests that most of these missing morphotypes were represented by species from those territories that went extinct during the Quaternary. Furthermore, reconstructing the hypothetical felid ensembles before Pleistocene extinctions rendered the continental felid faunas remarkably more similar to each other than they presently are, leaving their remaining, relatively minor differences to outstanding geographic singularities of each continental land mass.Fil: Morales, Miriam Mariana. Universidad Nacional de Jujuy; Argentina. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Giannini, Norberto Pedro. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin

Fehr foods: a step forward in Nutresa’s expansion plan

In 2009, Grupo Nutresa, Colombia’s largest food company set an ambitious and challenging growth plan for the years to come -- Bearing in mind the competitiveness and potential of its business units overseas, since the year 2000 the company defined the internationalization process as a key objective for its business model development and sustainable growth (Grupo Nutresa, Informe anual y de sostenibilidad, 2013) -- As part of it, the Americas were defined as the strategic region to continue on with its market enlargement and penetration plan -- In 2009, the Investment Banking Firm McColl Partner, LLC (which had recently carried out an investment process for Grupo Nutresa’s sister company, Grupo Argos), came into contact with Nutresa suggesting them the acquisition of Fehr Foods, a leading value-priced retail packaged cookie manufacturing company in the U.S. -- Known today as Abimar Foods, this acquisition was consistent with the company’s previously defined expansion plan to enter the U.S. market -- According to Grupo Nutresa Biscuits Business Unit perspective, it was aligned with their management and business policies, and their sales were supported through a local facility (Grupo Nutresa, personal communication, April, 25th, 2015) -- The purchasing process was relatively quick and in 2010 Fehr Foods was incorporated to Grupo Nutresa Biscuits Business Unit. About a year later, Mr. 4M, who was the financial manager of the Cookies Business, was designated as Fehr Foods’ CE

Efecto de un programa de estacionalidad de partos sobre la producción de leche en un hato de Pereira, Risaralda.

El ganado de leche en el periodo post-parto experimenta diferentes cambios fisiológicos como son el aumento de requerimiento energético y aumento de la temperatura que intervienen de forma negativa. Esto indica que durante este tiempo se requiere alimentación y temperatura adecuada para mantener la homeostasis y producción del animal. En algunos hatos lecheros la época de partos coincide con alta temperatura causando estrés calórico y poco consumo de materia seca, afectando tanto la parte productiva como la rentabilidad de las fincas. El programa de estacionalidad de partos es una alternativa que podría permitir la disminución de estos efectos negativos, por lo que se necesitaría evaluar sus verdaderos efectos sobre la producción de leche en el ganado. El objetivo de este estudio fue analizar el efecto de un programa de estacionalidad de partos sobre la producción de leche en el hato Londoburgo en Risaralda. Para esto, se determinaron las épocas frías del año haciendo una medición diaria a cada hora de la temperatura y de los milímetros de lluvia en la zona durante agosto del 2015 hasta junio del 2016. Se recogieron los datos de producción de leche de 215 vacas Holstein x Gyr en los 2 años anteriores al establecimiento del programa de estacionalidad de partos y los datos de estas mismas luego de ser establecido el programa. Con estos datos se realizó una comparación de las producciones antes y después del programa de estacionalidad de partos con una prueba t-Student. Al realizar el análisis estadístico se pudo concluir que no existe un aumento significativo en la producción de leche por vaca al día en el mes con la implementación del programa de estacionalidad de partos