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Método para el Desarrollo Ágil de Videojuegos Guiado por Experiencias
Get PDFThe video game industry today provides many facilities to micro and small businesses to create and publish their games, this thanks to the opening of new markets, mainly the social networking and mobile technology. These emerging companies do not alway
MODELACIÓN ESTOCÁSTICAS DE LA INTERACCIÓN ENTRE CELULAS CANCEROSAS Y CÉLULAS DE LA BMU
Get PDFLa metástasis ósea consiste en la invasión del cáncer al cuerpo humano, permitiendo la proliferación de tumores que atacan al hueso, alterando la dinámica natural de las células que realizan la remodelación ósea (osteoclastos y osteoblastos). Es conocido que las células cancerosas para reproducirse necesitan de sustancias que son segregadas por osteoclastos y osteoblastos durante el proceso de la remodelación ósea.
En la literatura, ya se encuentran modelos que describen la interacción de los osteoclastos, osteoblastos y las células cancerosas, pero estos modelos no incluyen las variaciones aleatorias asociadas a los niveles de nutrientes o diferencias intrínsecas de cada persona de una población. Por ello, en este trabajo se construye un modelo diferencial estocástico que incluye el efecto de las variaciones medioambientales en la interacción entre las células cancerosas, osteoclastos y osteoblastos. Este modelo estocástico está basado en un sistema determinista tipo Komarova, al cual se le incorpora un ruido blanco mediante la técnica de perturbación de parámetros. Se prueba la existencia, unicidad y positividad de solución del modelo estocástico propuesto, y se dan condiciones suficientes para caracterizar si la invasión del cáncer persiste o se extingue. Finalmente se realiza un análisis cuantitativo mediante simulaciones numéricas, verificando de forma gráfica los resultados obtenidos en cada dinámica
Expected Discounted Penalty Functions and Wiener-Hopf factorization for two-sided jumps Lévy risk processes
Get PDFConsideramos la clase de procesos de Levy X = fX(t); t 0g denidos mediante
expresiones de la forma
X(t) = ct +
B(t) + Z(t) S(t);
0;
donde c 0 es un termino de deriva, B = fB(t); t 0g es un movimiento browniano con media
cero, Z = fZ(t); t 0g es un proceso Poisson compuesto tal que la magnitud de sus saltos tienen
transformada de Laplace racional y S = fS(t); t 0g es un proceso de Levy de puros saltos, con
saltos positivos. Suponemos que B, Z y S son independientes.
En este trabajo estudiamos la factorizacion de Wiener-Hopf de esta clase de procesos. En
particular nos enfocamos en el factor negativo de Wiener-Hopf, que corresponde al nmo del proceso
tomado en el intervalo de cero hasta un tiempo aleatorio exponencial.
Identicamos explcitamente el subordinador asociado a este factor negativo, y utilizamos este
resultado para obtener una expresion para la funcion de densidad de dicho factor. Esta densidad
esta expresada en terminos de los parametros del proceso y funciones conocidas; por ejemplo, una
funcion q-escala de un proceso de Levy espectralmente negativo asociado a X.
Utilizamos los resultados anteriores para obtener una expresion para la Funcion de penalidad
descontada esperada generalizada (o funcion de Gerber-Shiu generalizada) asociada a procesos de la
forma u + X, donde u 0.
Estudiamos tambien un caso particular del proceso u+X, que corresponde a un proceso de riesgo
con saltos positivos y negativos, perturbado por un movimiento -estable. Para este caso particular
se obtuvieron expresiones asintoticas para la probabilidad de ruina y para la cola conjunta de la
severidad de la ruina y el capital previo a la ruina
Topology Optimization Benchmark I. Results for Minimum Compilance and Minimum Volume in Plane Stress Problems
Get PDFThis article proposes a benchmark set of problems for xed mesh topology optimization in 2 dimen-
sions. We have established the problems based on an analysis of more than 100 articles in the specialized
literature, gathering the most common dimensions, loads and xed regions used by researchers. Most of
the problems reported in specialized literature present di erences in speci cations such as lengths, units,
materials, etcetera, by instance, some articles propose the same proportions and geometrical shape but
di erent dimensions. Hence, the purpose of this benchmark is to unify geometrical and mechanical char-
acteristics and load conditions, considering that the proposed problems must to be realistic, in the sense
that the units are in the international system and a real-world material is used as well as load conditions.
The nal benchmark integrates 13 problems for plane stress using ASTM A-36 steel. Additionally, we
report an approximation to the optimum solution for the compliance and volume problems (maximize
sti ness with volume constraint and minimizing volume with a stress constraint respectively) using the
Solid Isotropic Material with Penalization (SIMP) method and a new proposed method based on SIMP
plus bisection with a Stress Constraint(SIMPSC). In-house implementations of both methods (whose
are freely available for academic applications) are used
SOME RESULTS IN QUOTIENT STACKS
Get PDFMany interesting kind of geometric-algebraic stacks are defined as the quotient stack associated
to a groupoid in algebraic spaces. More precisely, if (U; R; s; t; c) is a groupoid in
algebraic spaces we have the quotient stack [U=R]. Some of them are quotients by the action
of a group space into an algebraic space. When we have 1-morphisms X 􀀀! Z and Y 􀀀! Z
of quotient stacks, some natural questions arise: if a fibre or a 2-fibre product exists, is this
also a quotient stack? If the answer is armative, what is the associated groupoid? What if
one of those 1-morphisms has an special property like to be an open immersion? In this work
we are going to give some results about these questions, trying to solve it in the most general
possible case.
While in categories over a fixed category C there are always a fibre product and a 2-fibre
product, when we are working with fibred categories we have found that a fibre product does
not always exist. However, we found a condition about the fibred product as a category over
C and a class of fibred categories and 1-morphisms for which fibre product can always be
constructed. We say that the fibre product has componentwise pullbacks if it satisfies that
condition. In particular, when we define a quotient stack as the stackification of the fibred
category associated to a functor induced by a groupoid in algebraic spaces, the fibred category
belongs to this class and we can take the fibre produc
ROBUST ALGORITHMS FOR THE ANALYSIS OF THE BRAIN STRUCTURE USING DIFUSSION
Get PDFOnes of the most challenging goals in neuroimaging are to infer axonal connectivity patterns and tissue properties on extit{in vivo} brains through water diffusion estimation in cerebral tissue. To this aim, the Diffusion--Weighted Magnetic Resonance Imaging technique is used. This technique allows one to estimate the preferred orientations of water diffusion in brains. Such a diffusion, in the white matter case, is constrained by the axonal structure. That information is very useful in neuroscience research due to the changes in the connectivity patterns associated with neurological disorders and, in general, associated with brain development. There are two important stages to infer axonal connectivity: 1) to analyze the intra--voxel Diffusion--Weighted Magnetic Resonance signals for recovering the local fiber structure, and 2) to apply, over the recovered intra--voxel information, a tractography technique that estimates neuronal tract pathways to determine both global structure and connectivity in human brains. In this work, we propose robust strategies to estimate the intra--voxel fiber structure and the global fiber bundle trajectory. Thus, we present a sparse and adaptive diffusion dictionary based method to estimate the local intra--voxel axonal fiber populations on extit{in vivo} brain data. Our proposal overcomes the following limitations of the diffusion dictionary--based methods: the limited angular resolution and the incapability to estimate tissue properties for different fiber bundles. We propose to iteratively re--estimate the orientations and the diffusivity profile of the atoms independently at each voxel by solving surrogate models based on mathematical simplifications. As a result, we improve the fitting of the Diffusion--Weighted Magnetic Resonance signal. We also propose a new method to estimate axonal fiber pathways from the intra--voxel information. Our method uses the multiple local orientation information for leading stochastic walks of particles. These stochastic particles are modeled with mass, hence, they are subject to gravitational and inertial forces. As result, we obtain smooth, filtered and compact bundle trajectories. This gravitational interaction can be seen as a flocking behavior among particles that promotes better and robust axon fiber estimations because the particles use collective information to move. Both proposals are evaluated on realistic numeric diffusion phantoms, a physical diffusion phantom and on ex
Estrategias de Negociación y Contratos en Juegos no Cooperativos
Get PDFLa Teoría de Juegos es el estudio de modelos matemáticos que describen el conflicto y la cooperación entre entes inteligentes que toman decisiones. Los modelos de Teoría de Juegos se agrupan en dos grandes grupos, cada uno d
Desarrollo de un Marco de Trabajo para la Protección de un Equipo de Respuesta ante Incidencias de Seguridad Informática (CSIRT)
Get PDFLos recursos informáticos ayudan a las organizaciones a realizar sus labores cotidianas de diferentes formas, ya sea para comunicarse con sus clientes o proveedores en general, así como para generar contenido informático. Es por el
Bayesian analysis of a Model for Glucose-Insulin dynamics during the Oral Glucose Tolerance Test (OGTT)
Get PDFDiabetes Mellitus 2 is a metabolic disorder. Its prevalence has been increasing all over the world. The Oral Glucose Tolerance Test (OGTT) allows to diagnose some anomalies related to the status of the disease. This work presents a model for the dynam