Problemas de sistemas de ecuaciones lineales en libros de texto de 3º ESO

La resolución de problemas en matemáticas ha sido uno de los principales focos de investigación y discusión en los últimos 30 años. Las propuestas curriculares para la educación primaria y secundaria la recogen como eje transversal. El libro de texto es agente fundamental en el proceso de enseñanza aprendizaje, y en el trabajo en el aula. En este estudio se analiza cómo se plasma la resolución de problemas en un libro de texto, centrando la atención en el tema de Sistemas de Ecuaciones lineales del tercer curso de la Educación Secundaria Obligatoria. Se concluye que existen importantes características que son poco coherentes con lo especificado en el currículo oficial

La resolución de problemas en los libros de texto: un instrumento para su análisis

Este artículo muestra un instrumento para analizar el papel de la resolución de problemas en los libros de texto. Partimos de la descripción del papel otorgado a los libros de texto en los procesos de enseñanza y aprendizaje de las matemáticas, para pasar después a mostrar algunas investigaciones que, desde la educación matemática, se han realizado sobre libros de texto, entre ellas las llevadas a cabo en nuestro grupo. De estas últimas mostraremos ejemplos de cómo el instrumento de análisis señalado permite analizar los tipos de problemas que aparecen en los libros de texto

Icosahedral Ni nanowires formed from nanocontacts breaking: Identification and characterization by Molecular Dynamics

We present and discuss an algorithm to identify and characterize the long icosahedral structures (staggered pentagonal nanowires with 1-5-1-5 atomic structure) that appear in Molecular Dynamics simulations of metallic nanowires of different species subjected to stretching. The use of this algorithm allows the identification of pentagonal rings forming the icosahedral structure as well as the determination of its number np , and the maximum length of the pentagonal nanowire Lpm. The algorithm is tested with some ideal structures to show its ability to discriminate between pentagonal rings and other ring structures. We applied the algorithm to Ni nanowires with temperatures ranging between 4K and 865K, stretched along the [111], [100] and [110] directions. We studied statistically the formation of pentagonal nanowires obtaining the distributions of length Lpm and number of rings np as function of the temperature. The Lpm distribution presents a peaked shape, with peaks located at fixed distances whose separation corresponds to the distance between two consecutive pentagonal rings

La résolution des problèmes dans les manuels: un instrument d'analyse

Este artículo muestra un instrumento para analizar el papel de la resolución de problemas en los libros de texto. Partimos de la descripción del papel otorgado a los libros de texto en los procesos de enseñanza y aprendizaje de las matemáticas, para pasar después a mostrar algunas investigaciones que, desde la educación matemática, se han realizado sobre libros de texto, entre ellas las llevadas a cabo en nuestro grupo. De estas últimas mostraremos ejemplos de cómo el instrumento de análisis señalado permite analizar los tipos de problemas que aparecen en los libros de texto.Este artigo mostra um instrumento para analisar o papel da resolução de problemas em livros didáticos. Começamos com a descrição do papel dado aos livros didáticos no ensino e aprendizagem da matemática, em seguida, passar para mostrar alguma pesquisa da educação matemática, têm sido realizados sobre livros didáticos, incluindo os realizados colocar em nosso grupo. Destes exemplos mostram como a ferramenta de análise apontou para analisar os tipos de problemas que aparecem nos livros didáticos.This article shows an instrument to analyse the role of problem solving in textbooks. We begin with the description of the role given to the textbooks in the teaching and learning of mathematics, then move on to show some research on textbooks from mathematics education, including those carried out in our group. We show examples of the mentioned research about how the instrument for analysis allows us to analyse the different kinds of problems that appear in textbooksCet article montre un instrument pour analyser le rôle de la résolution de problèmes dans les manuels scolaires. Nous commençons par la description du rôle donné aux manuels scolaires dans l'enseignement et l' apprentissage des mathématiques, puis passer à montrer un peu de recherche de l'enseignement des mathématiques, ont été menées sur les manuels scolaires, y compris ceux effectués placer dans notre groupe. Parmi ces exemples montrent comment l'outil d'analyse a pour analyser les types de problèmes qui apparaissent dans les manuels scolaires

SMS-Builder: An adaptive software tool for building systematic mapping studies

A Systematic Mapping Study is an instrument frequently used to carry out a search process, identification, and classification of studies in different fields. Researchers in front of this type of process have a challenge while managing the data about these studies. This paper presents a software tool that has been created to help those who need to build a systematic mapping study. In addition, this work follows the evidence-based software engineering approach and extends it through a software tool by including different ways of adapting this process

Characterization of the complete chloroplast genome of a Peruvian landrace of Capsicum chinense Jacq. (Solanaceae), arnaucho chili pepper

In this study, we sequenced the first complete chloroplast (cp) genome of a Peruvian chili pepper landrace, “arnacucho” (Capsicum chinense). This cp genome has a 156,931 bp in length with typical quadripartite structure, containing a large single copy (LSC) region (87,325 bp) and a 17,912 bp small single-copy (SSC) region, separated by two inverted repeat (IR) regions (25,847 bp); and the percentage of GC content was 37.71%. Arnaucho chili pepper chloroplast genome possesses 133 genes that consists of 86 protein-coding genes, 37 tRNA, eight rRNA, and two pseudogenes. Phylogenetic analysis revealed that this Peruvian chili pepper landrace is closely related to the undomesticated species C. galapagoense; all belong to the Capsiceae tribe

Characterization of the complete chloroplast genome of a Peruvian landrace of Capsicum chinense Jacq. (Solanaceae), arnaucho chili pepper

In this study, we sequenced the first complete chloroplast (cp) genome of a Peruvian chili pepper landrace, “arnacucho” (Capsicum chinense). This cp genome has a 156,931 bp in length with typical quadripartite structure, containing a large single copy (LSC) region (87,325 bp) and a 17,912 bp small single-copy (SSC) region, separated by two inverted repeat (IR) regions (25,847 bp); and the percentage of GC content was 37.71%. Arnaucho chili pepper chloroplast genome possesses 133 genes that consists of 86 protein-coding genes, 37 tRNA, eight rRNA, and two pseudogenes. Phylogenetic analysis revealed that this Peruvian chili pepper landrace is closely related to the undomesticated species C. galapagoense; all belong to the Capsiceae tribe

Capabilities of Nanostructured Tungsten for Plasma Facing Material

One of the bottle necks for fusion to become a reality is the lack of materials able to withstand the harsh conditions taken place in a reactor environment. In particular, plasma facing materials (PFM) have to resist large radiation fluxes and thermal loads. Nowadays, tungsten is one of the most attractive materials proposed for PFM. However, it is known that the irradiation of tungsten with H leads to surface blistering and subsequent cracking and exfoliation which is unacceptable. In particular, these effects have been observed to be more severe when W is subjected to pulse irradiation

Resistance against two lytic phage variants attenuates virulence and antibiotic resistance in Pseudomonas aeruginosa

BackgroundBacteriophage therapy is becoming part of mainstream Western medicine since antibiotics of clinical use tend to fail. It involves applying lytic bacteriophages that self-replicate and induce cell lysis, thus killing their hosts. Nevertheless, bacterial killing promotes the selection of resistant clones which sometimes may exhibit a decrease in bacterial virulence or antibiotic resistance.MethodsIn this work, we studied the Pseudomonas aeruginosa lytic phage φDCL-PA6 and its variant φDCL-PA6α. Additionally, we characterized and evaluated the production of virulence factors and the virulence in a Galleria mellonella model of resistant mutants against each phage for PA14 and two clinical strains.ResultsPhage φDCL-PA6α differs from the original by only two amino acids: one in the baseplate wedge subunit and another in the tail fiber protein. According to genomic data and cross-resistance experiments, these changes may promote the change of the phage receptor from the O-antigen to the core lipopolysaccharide. Interestingly, the host range of the two phages differs as determined against the Pseudomonas aeruginosa reference strains PA14 and PAO1 and against nine multidrug-resistant isolates from ventilator associated pneumonia.ConclusionsWe show as well that phage resistance impacts virulence factor production. Specifically, phage resistance led to decreased biofilm formation, swarming, and type III secretion; therefore, the virulence towards Galleria mellonella was dramatically attenuated. Furthermore, antibiotic resistance decreased for one clinical strain. Our study highlights important potential advantages of phage therapy’s evolutionary impact that may be exploited to generate robust therapy schemes