Space Forms and Group Resolutions: the tetrahedral family

The orbit polytope for a finite group G acting linearly and freely on a sphere S is used to construct a cellularized fundamental domain for the action. A resolution of the integers over G results from the associated G-equivariant cellularization of S. This technique is applied to the generalized binary tetrahedral group family; the homology groups, the cohomology rings and the Reidemeister torsions of the related spherical space forms are determined.Comment: 37 pages, 5 figures. A proof of the minimal rank property for the resolution has been adde

The ring of sections of a complete symmetric variety

We study the ring of sections A(X) of a complete symmetric variety X, that is of the wonderful completion of G/H where G is an adjoint semi-simple group and H is the fixed subgroup for an involutorial automorphism of G. We find generators for Pic(X), we generalize the PRV conjecture to complete symmetric varieties and construct a standard monomial theory for A(X) that is compatible with G orbit closures in X. This gives a degeneration result and the rational singularityness for A(X).Comment: 15 pages, Late

Pl\:ucker relations and spherical varieties: application to model varieties

A general framework for the reduction of the equations defining classes of spherical varieties to (maybe infinite dimensional) grassmannians is proposed. This is applied to model varieties of type A, B and C; in particular a standard monomial theory for these varieties is presented.Comment: 15 pages, accepted for publication in Transformation Group

High Temperature Phase Stability in Doped Thermal Barrier Coating Systems

One of the most used materials for Thermal Barrier Coatings manufacturing is Zirconia stabilized by addition of Yttrium oxides as dopant. It has been found that further addition of Rare Earth element oxides as luminescent codopant to TBC systems is not only a basic requirement for the adoption of the thermographic phosphor technique, but it could also contribute to reducing the overall coating thermal conductivity by as much as 50% from current levels, so that larger temperature gradients can be established through the TBC without excessive augmentation of its thickness. Since the final lattice structure strongly affects the general mechanical and thermal properties of the TBC, the stability of the desired crystal configuration over a wide range of temperature is a fundamental prerequisite for a successful TBC design. In fact, while phase stability is not a sufficient condition to ensure high durability, its absence is generally agreed to be severely detrimental to TBC cyclic life. The aims of this thesis were: 1. defining some criteria to choose a suitable codopant which would allow the possibility of using thermographic phosphor techniques and, at the same time, of reducing the TBC thermal conductivity; 2. evaluating the structural stability of the manufactured codoped TBC specimens. The research work for this thesis has been conducted at the ‘National High Temperature Surface Engineering Centre’ sited within Cranfield University. This centre has extensive facilities for Physical Vapour Deposition, Chemical Vapour Deposition and Low Vacuum Plasma Spray coating of high temperature components, not to mention the only university facilities in Europe to deposit thermal barrier coatings onto blades by Electron Bean Physical Vapour Deposition. The accessibility to comprehensive high-temperature coating test facilities also offered a wide knowledge background for the completion of the present work

Cellularization for exceptional spherical space forms and application to flag manifolds

Given a finite group acting freely and isometrically on a Euclidean sphere, it is natural to look for an equivariant cellular decomposition of the sphere. In this way, one obtains a cellular decomposition of the quotient manifold, called a spherical space form. In this paper, we apply the method developped by the first and third authors, using the so-called orbit polytope, to construct an explicit cellular decomposition of the (4n-1)-sphere with respect to the binary octahedral and the binary icosahedral groups, and describe the associated cellular homology chain complex. As an application we find free resolutions of the constant module over these groups and deduce their integral cohomology. Moreover, we use the octahedral case to describe a cellular structure on the flag manifold of \R^3 that is equivariant with respect to the Weyl group action.Comment: submitted to Annales de l'Institut Fourie

Modelamiento de nicho ecológico en Heterophrynus boterorum (Phrynidae) en los Andes Centrales, Colombia

The species Heterophrynus boterorum is endemic to Colombia, and was described in 2013 with just a few specimens. It has morphological variation that may be correlated with environmental conditions, or with isolation processes. We modeled the potential distribution of this species using software Maxent in order to know of other possible occurrence localities and the influence of environmental variables which can condition its presence. Additionally, we contrasted the potential distribution with the National System of Protected Areas of Colombia. The species has a potential distribution in the central region of the Andes in the Cordillera Central and Occidental, which connects all known populations. Precipitation and temperature, especially during the driest season, were the most influential variables in the model, which is coherent regarding the requirements for humidity and climatic stability in Amblypygi. Only one of the known populations is recorded in a protected area, so it is necessary to design better conservation strategies to preserve H. boterorum.La especie Heterophrynus boterorum es endémica de Colombia, fue descrita en 2013 y han sido registrados pocos especímenes. Presenta variación morfológica, la cual podría asociarse con las condiciones ambientales, o a procesos de aislamiento. Se modeló la distribución potencial de la especie usando MaxEnt, para conocer otras posibles localidades de ocurrencia y la influencia de las variables ambientales que pueden condicionar su presencia. Adicionalmente, se contrastó la distribución potencial con el Sistema de Áreas Protegidas en Colombia. La especie presenta una distribución potencial hacia la región central de los Andes, sobre las Cordilleras Central y Occidental. La precipitación y la temperatura, en especial durante la temporada más seca, fueron las variables más influyentes en el modelo, lo cual es coherente con los requerimientos de humedad y estabilidad climática en Amblypygi. Solo una de las poblaciones conocidas está registrada dentro de un área protegida, por tanto, es necesario diseñar mejores estrategias de conservación para preservar a H. boterorum

Análisis de las metodologías pedagógicas desarrolladas en el área de tecnología e informática para el fortalecimiento de las competencias digitales del colegio Técnico Tomás Rueda Vargas

Este documento da cuenta de una investigación realizada a una comunidad educativa de bajos recursos, con un alto índice de vulnerabilidad y necesidades básicas insatisfechas, como la falta de oportunidades laborales, desatención en salud y alto índice de desescolarización, condición que evidencia la problemática que enfrentan los estudiantes por no tener las mismas posibilidades laborales en el medio que lo rodea, debido a la zona donde se ubican, a la problemática social que se enfrentan y a la falta de recursos económicos con que cuentan; de allí surge la necesidad de facilitar herramientas educativas que enfoquen al estudiante de educación básica secundaria y media a fortalecer las competencias digitales, que permitan afianzar no solo sus conocimientos, sino además sus competencias en la información, la comunicación, la creación de contenidos, la seguridad y la resolución de problemas. A partir de la problemática planteada se define que la investigación es de carácter cualitativo para dar respuesta teórica y a partir de resultados reales dar respuesta de forma práctica a las dificultades planteadas en esta comunidad educativa En este sentido, este estudio se realizó a partir del enfoque metodológico cualitativo que permitió orientar el proyecto dando respuesta al objetivo principal. Finalmente, se realizó el análisis sobre los resultados obtenidos a partir de los instrumentos de recolección y análisis, los cuales evidencian el uso de metodologías teóricas y pocas prácticas

Propuesta de una metodología para la aplicación del principio enfoque por procesos de la norma ISO 9001:2015 numeral 4.4 en la empresa mantenimiento profesional de superficies Mps S.A.S

El propósito del presente trabajo es optimizar los procesos claves en la empresa MPS S.A.S, siguiendo los lineamientos del enfoque por procesos de la norma ISO 9001:2015 numeral 4.4 el cual, contempla en sus numerales que la organización fija recursos, métodos, asigna responsabilidades para controlar y mejorar sus procesos y procedimientos. El enfoque se presenta como una estrategia de aplicación dirigida a la estructura organizacional de la empresa con el fin de generar cambios significativos en su funcionamiento. Se contempla que los procesos han de identificarse y medirse con el fin de ejercer un control que a su vez se vea reflejado en un valor agregado y pueda generar ventaja competitiva. Pero el éxito del enfoque depende en gran parte del impacto que genere por lo que requiere de una estrategia de aplicabilidad que garantice unos buenos resultados. Atendiendo la se plasma en la metodología una serie de pasos, los cuales garantizan una excelente aplicabilidad del enfoque en la organización.The purpose of the present work is to optimize the key processes in the company MPS SAS, following the guidelines of the process approach of ISO 9001: 2015 clause 4.4 which, in its numerals, establishes that the organization fixes resources, methods, assigns responsibilities to control and improve their processes and procedures. The approach is presented as an implementation strategy directed at the organizational structure of the company in order to generate significant changes in its functioning. It is contemplated that the processes have to be identified and measured in order to exercise a control that in turn is reflected in an added value and can generate competitive advantage. But the success of the approach depends in large part on the impact it generates by what it requires of a strategy of applicability that guarantees good results. Taking into account the methodology in a series of steps, which ensure an excellent applicability of the approach in the organization

Determinar si los establecimientos comerciales ubicados en el sector de Portalegre en el municipio de Soacha tienen implementado el sistema de gestión de la seguridad y salud en el trabajo (SG-SST)

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