Dealing with degenerated cases in quadratic programming

A new algorithm is described for quadratic programming which is based on a Cholesky factorization that uses a diagonal pivoting strategy and that allows to compute null or negative curvature directions. The algorithm is numerically stable and has shown efficiency solving positive-definite and indefinite problems. It is specially interesting in indefinite cases because the initial point does not need to be a vertex of the feasible set. So we avoid introducing artificial constraints in the problem, which turns out to be very efficient in parametric programming. At the same time techniques for updating matrix factorizations are used

An infeasible Predictor-Corrector Interior Point Method Applied to Image Denoising

Projet PROMATHImage recovery problems can be solved using optimization techniques. In this case, they often lead to the resolution of either a large scale quadratic program, or, equivalently, to a nondifferentiable minimization problem. Interior point methods are widely known for their efficiency in linear programming. Lately, they have been extended with success to the resolution of linear complementary problems, (LCP), which include convex quadratic programming. We present an infeasible predictor-corrector interior point method, in the general framework of monotone (LCP). The algorithm has polynomial complexity. We also prove it converges globally, with asymptotic quadratic rate. We apply this method to the denoising of images. In the implementation we take advantage of the underlying structure of the problem, specially its sparsity. We obtain good performances, that we assess by comparing the method with a variable-metric proximal bundle algorithm applied to the resolution of the equivalent nonsmooth problem

A Trust region interior point algorithm for linearly constrained optimization

Projet PROMATHWe present an extension for nonlinear optimization under linear constraints, of an algorithm for quadratic programming using a trust region idea, introduced by Ye and Tse and extended by Bonnans and Bouhtou. Due to the nonliearity of the cost we use a linesearch in order to reduce the step if necessary. We prove that, under suitable hypotheses, the algorithm converges to a point satisfying the first-order optimality system and we analyse under which conditions the unit stepsize will be asymptotically accepted

Características estructurales de un bosque de pino en Tlalnepantla, Morelos

El principal tipo de vegetación del municipio Tlalnepantla, localizado al noreste del estado de Morelos, corresponde al de bosques templados de pino y de pino-encino. Forma parte de la zona de amortiguamiento y de recarga de mantos del centro de la entidad. En la localidad La Correa se hizo una descripción dasonómica de la población forestal y un diagnóstico de la situación sanitaria del arbolado, como antecedente para diseñar un proyecto ecoturístico local. Se aplicó un muestreo sistemático mediante el establecimiento de 20 parcelas de 1/10 ha. Las condiciones sanitarias de la copa, el tronco y el vigor, se analizaron con una prueba de X2. El análisis demográfico se hizo mediante tablas de vida estática y se diseñaron curvas de supervivencia para cada especie. Se realizó un análisis morfométrico a partir del porcentaje de copa, el índice de copa, la dimensión de la copa, el índice de espacio vital y el grado de esbeltez por clase natural de edad por taxón, como indicadores de competencia y calidad de sitio del arbolado. Se identificaron cuatro especies: Pinus patula, P. ayacahuite, P. leiophylla y P. montezumae. Los resultados indican que el bosque de pino estudiado es una masa mixta regular, con una densidad promedio de 437 ejemplares ha-1, conformada, principalmente, por individuos jóvenes que se desarrollan en lugares propios de baja competencia, con buenos porcentajes sanitarios y vigorosos

Delitos informáticos que afectan los consumidores financieros del Banco Davivienda

A la par de la evolución tecnológica, la cual ha sido impulsada por la innovación, la transformación digital y acelerada por la pandemia por Covid-19, el sector financiero ha afrontado un aumento en los índices de delitos informáticos. Esta situación ha obligado a las entidades financieras a adoptar, implementar o reforzar sus sistemas de gestión de seguridad informática, teniendo en cuenta no solo que la información es el activo empresarial más importante sino en ofrecer a sus clientes niveles de seguridad adecuados que generen confianza y experiencias positivas al momento de usar los canales digitales. Tanto los entes reguladores como las entidades financieras han invertido una gran cantidad de recursos y esfuerzos para minimizar el riesgo de ser víctimas de delitos informáticos, en buena parte orientados a diseñar e implementar campañas enfocadas en sensibilizar a los usuarios acerca de las modalidades delictivas y la forma en que pueden prevenir ser víctimas de estas. Con el presente trabajo se realizará recolección de información a través de una encuesta a 180 consumidores del banco Davivienda, con el objetivo de determinar el índice de conocimiento de los encuestados sobre las modalidades delictivas, existencia de la campaña de sensibilización “La Tía Segura” y que tan efectiva es esta campaña.Along with technological evolution, which has been driven by innovation, digital transformation accelerated by the covid-19 pandemic, the financial sector has faced an increase in computer crime rates. This situation has obliged financial entities to adopt, implement or reinforce their systems of computer security management, taking into account not only that information is the most important business asset but in offering its customers levels of security convenient to generate confidence and positive experiences when using the digital channels. Both regulatory bodies and financial institutions have invested a great deal amount of resources and efforts to minimize the risk of being victims of crimes computerized, largely oriented to design and implement campaigns focused in making users aware of criminal modalities and the way in which can prevent being victims of these. With the present work, information will be collected through a survey of 180 consumers of the Davivienda bank, with the aim of determining the index of knowledge of those surveyed about criminal modalities, existence of the awareness campaign "La Tía Segura" and how effective is this campaign

Cellular Antioxidant Effects and Bioavailability of Food Supplements Rich in Hydroxytyrosol

The present study evaluates the effect of olive (Olea europaea L.) vegetation water on human cells regarding its antioxidant properties and radical scavenger bioactivities. To this aim, two food supplements containing concentrated olive water in combination with 6% lemon juice or 70% grape juice, respectively, were assessed in different oxidation assays. From the investigated polyphenols, hydroxytyrosol, present in olives and in a lesser extent in grapes, was found to be the most abundant in both formulations, followed by tyrosol and oleuropein for the olive-derived concentrate with lemon juice, and by proanthocyanidins and tyrosol for the olive concentrate with grape juice. Cellular studies suggest that both formulations are effective antioxidants. In particular, the combination of olive and grape extracts showed a remarkable superoxides-, hydroxyl radicals-, and hydrogen peroxides-scavenging activity, while the formulation containing 94% olive concentrate wasmore potent in protecting the cells against lipoxidation. Both products showed a significant and similar effect in preventing advanced glycation end products’ (AGEs) formation. In addition, preliminary data indicate that hydroxytyrosol is absorbed into the human body when administered via these hydrophilic matrices, as confirmed by the urinary excretion of free hydroxytyrosol. Since the availability of phytochemicals largely depends on the vehicle in which they are solved, these findings are of relevance and contribute to supporting the healthful effects here assessed in a cellular environment