Pseudospectral methods and numerical continuation for the analysis of structured population models

In this thesis new numerical methods are presented for the analysis of models in population dynamics. The methods approximate equilibria and bifurcations in a certain class of so called structured population models. Chapter 1 consists of an introduction to structured population dynamics, where the state of the art is presented through a classical consumer-resource model [44]. The necessity of new numerical methods for analyzing structured population models is discussed and motivated by their applications to life sciences. In Chapter 2 [44] is extended to a more general class in which a structured population with a unique state at birth interacts with an environment of unstruc- tured populations and interaction variables. Equilibrium types are defined, the model is linearized and a characteristic equation is obtained. Finally, a discussion about equilibria and bifurcations under parameter variation is included. In Chapter 3 a new pseudospectral method for the computation of eigenvalues of linear VFE/DDE systems is presented. The technique consists of constructing a finite approximation of the infinitesimal generator of the solution semigroup. The spectral convergence of the method is proved, and a piecewise variation which speeds up the computations presented and validated with toy models. An exten- sion to deal with structured population models is proposed and validated with the model in [44]. Chapter 4 is devoted to the numerical continuation of equilibrium branches and bifurcation curves under parameter variation for models of the class presented in Chapter 2. A new technique for the curve continuation is presented, where a reduction of the dimension and a simplification of the equilibrium conditions result in new test functions for the detection of transcritical bifurcations, reducing the computational cost. The methods were implemented in the development of routines that were tested and validated with models from the literature

Numerical Bifurcation Analysis of Physiologically Structured Populations: Consumer-Resource, Cannibalistic and Trophic Models

With the aim of applying numerical methods, we develop a formalism for physiologically structured population models in a new generality that includes con- sumer resource, cannibalism and trophic models. The dynamics at the population level are formulated as a system of Volterra functional equations coupled to ODE. For this general class we develop numerical methods to continue equilibria with respect to a parameter, detect transcritical and saddle-node bifurcations and compute curves in parameter planes along which these bifurcations occur. The methods combine curve continuation, ODE solvers and test functions. Finally we apply the method to the above models using existing data for Daphnia magna consuming Algae, and for Perca fluviatilis feeding on Daphnia magna. In particular we validate the methods by deriving expressions for equilibria and bifurcations with respect to which we compute rrors, and by comparing the obtained curves with curves that were computed earlier with other methods. We also present new curves to show how the methods can easily be applied to derive new biological insight. Schemes of algorithms are included

Ozone in Spain's National Parks and Protected Forests

In general, it is difficult to measure air pollutant concentrations in remote areas, as they are mostly national parks and protected areas. Passive samplers provide an accurate and inexpensive method for measuring cumulative exposures of different air pollutants. They have been used to collect ozone data in both laboratory and field at different geographical scales. The objective of the present study is to fill the knowledge gap regarding air quality in remote areas of Spain, such as national parks and protected areas. Because there were no systematic data sets on the main air pollutants that could affect these areas, an air quality measurement network was established between 2001 and 2004 on 19 locations inside Spanish national parks and protected areas. The data collected suggest that ozone levels in mountainous areas are high enough to affect sensitive vegetation. Most of the locations registered moderate-to-high ozone levels, with important interannual variability. Altitudinal ozone gradients were observed in most of the parks with complex topography due to the establishment of local circulations that incorporate polluted air masses from polluted airsheds or even long-range transport (i.e., Canary Islands). Different latitude-dependent, yearly cycles were also observed, showing two, one, or no clear peaks depending on the region. These findings extend to the most southerly locations, except in the Canary Islands, where pollution transported from other regions in the upper transport layers probably led to the high concentrations observed

Multifuncionalidad y Sistemas Agroalimentarios locales: prioridades de investigación e innovación en medio ambiente, territorio y desarrollo rural en el sector español del aceite de oliva

Los sistemas agroalimentarios locales (SIAL) de aceite de oliva en España son un buen ejemplo del comportamiento multifuncional y de su contribución potencial a la gobernanza territorial. Se detectan cambios significativos en la geografía del olivar español, derivados, por una parte, de la expansión de nuevas superficies de olivar en regadío de cultivo intensivo y superintensivo y, por otra, de la creciente marginalización a la que se ve abocado el olivar español de media y alta pendiente. Por otra parte, el olivar español produce un fuerte grado de externalidades ambientales negativas, como la erosión o la contaminación difusa de suelos y acuíferos. El principal objetivo del trabajo es detectar las relaciones que se establecen entre la definición de los principales problemas que atañen a los SIAL de aceite de oliva en España y las prioridades de investigación e innovación en materia de territorio y medio ambiente, desde una óptica multidisciplinar que integre enfoques procedentes de las Ciencias Sociales y de las Ciencias Agronómicas y Ambientales. El marco teórico procede de las teorías sobre la multifuncionalidad de los espacios rurales y sobre los SIAL. La metodología utiliza información cualitativa y cuantitativa procedente de dos fuentes primarias: i) un grupo de discusión integrado en un panel presencial de expertos sobre innovación en olivicultura, sostenibilidad y aprovechamiento de residuos; ii) un análisis Delphi dirigido a un conjunto amplio de expertos sobre medio ambiente, territorio y desarrollo rural sostenible en el sector oleícola. En cuanto al análisis de resultados, el grupo de discusión ha tenido como misión categorizar las grandes tipologías de olivicultura en España y sintetizar sus respectivos problemas ambientales y territoriales. Estos resultados sirven como marco de referencia del análisis Delphi, que tiene un doble objetivo: por una parte, el análisis de los principales problemas ambientales y territoriales de los SIAL oleícolas en España; por otra, el estudio de las prioridades en materia de programas y de grupos de líneas de investigación sobre la materia, así como las relaciones entre dichas líneas de investigación y los problemas a los que se enfrentan los SIAL oleícolas.prioridades de investigación e innovación, medio ambiente y territorio, análisis Delphi., Agribusiness, Agricultural and Food Policy, Community/Rural/Urban Development, Food Consumption/Nutrition/Food Safety, Labor and Human Capital,

Harvest index, a parameter conditioning responsiveness of wheat plants to elevated CO2

The expansion of the world’s population requires the development of high production agriculture. For this purpose, it is essential to identify target points conditioning crop responsiveness to predicted [CO2]. The aim of this study was to determine the relevance of ear sink strength in leaf protein and metabolomic profiles and its implications in photosynthetic activity and yield of durum wheat plants exposed to elevated [CO2]. For this purpose, a genotype with high harvest index (HI) (Triticum durum var. Sula) and another with low HI (Triticum durum var. Blanqueta) were exposed to elevated [CO2] (700 µmol mol–1 versus 400 µmol mol–1 CO2) in CO2 greenhouses. The obtained data highlighted that elevated [CO2] only increased plant growth in the genotype with the largest HI; Sula. Gas exchange analyses revealed that although exposure to 700 µmol mol–1 depleted Rubisco content, Sula was capable of increasing the light-saturated rate of CO2 assimilation (Asat) whereas, in Blanqueta, the carbohydrate imbalance induced the down-regulation of Asat. The specific depletion of Rubisco in both genotypes under elevated [CO2], together with the enhancement of other proteins in the Calvin cycle, revealed that there was a redistribution of N from Rubisco towards RuBP regeneration. Moreover, the down-regulation of N, NO3 –, amino acid, and organic acid content, together with the depletion of proteins involved in amino acid synthesis that was detected in Blanqueta grown at 700 µmol mol–1 CO2, revealed that inhibition of N assimilation was involved in the carbohydrate imbalance and consequently with the down-regulation of photosynthesis and growth in these plants

Desarrollo de una placa de osteosíntesis personalizada como técnica de fijación y posicionamiento simultáneo del maxilar superior en osteotomías tipo Lefort I en cirugía ortognática

En este estudio se desarrolla una técnica de posicionamiento y fijación para osteotomías tipo Lefort I en cirugía ortognática. En concreto, se lleva a cabo una prueba de concepto de diseño de una placa de osteosíntesis multifunción customizada. Inicialmente se han analizado parámetros influyentes en la morfología y situación de la placa, según lo cual se ha diseñado la placa. Este diseño se ha validado mediante la impresión 3D de prototipos plásticos y ha sido validado por un cirujano maxilofacial especialista en cirugía ortognática. El resultado del diseño CAD (Computer-Aided Design) de la placa de osteosíntesis ha sido exitoso y se ha completado en un tiempo aceptable para una cirugía electiva. Gracias a las características de la placa se prevé que aumente la precisión del procedimiento y que, por tanto, se obtengan mejores resultados clínicos

Desarrollo de una placa de osteosíntesis personalizada como técnica de fijación y posicionamiento simultáneo del maxilar superior en osteotomías tipo Lefort I en cirugía ortognática

En este estudio se desarrolla una técnica de posicionamiento y fijación para osteotomías tipo Lefort I en cirugía ortognática. En concreto, se lleva a cabo una prueba de concepto de diseño de una placa de osteosíntesis multifunción customizada. Inicialmente se han analizado parámetros influyentes en la morfología y situación de la placa, según lo cual se ha diseñado la placa. Este diseño se ha validado mediante la impresión 3D de prototipos plásticos y ha sido validado por un cirujano maxilofacial especialista en cirugía ortognática. El resultado del diseño CAD (Computer-Aided Design) de la placa de osteosíntesis ha sido exitoso y se ha completado en un tiempo aceptable para una cirugía electiva. Gracias a las características de la placa se prevé que aumente la precisión del procedimiento y que, por tanto, se obtengan mejores resultados clínicos

Synthesis of Fe-Au nanoparticles through phase separation using the gas aggregation technique

During the last veers different type of magnetic materials have been obtained either alloys or nanopor-ritlcs with severall metalllics shells. These particle exhibt better magnetic properties, are biocompatible and have optical properties due to their shell noble metal layer, this is possible, to synthesize heterostructured nanoparticles with care/shell structure by using sputtering targets consisting of alloys of different materials. In the case of such materials have different surface energies and atomic sizes, there are diffusion processes which lead to the formation of structured nanoparticles with a shell and core having different composition. In this work we will show the results obtained about Fe-Au nanoparticles grown by I he gas aggregation technique, using magnetron sputering sources. Colloids prepared from sputtered deposits of heterostructed nanoparticles exhibit less aggregation when compared to suspensions obtained from pure magnetic materials. Spectrophotometry measurement show the presence of gold at the surface of the nanoparticles. Magnetic properties of such particle are analyzed by VSM. Compasition end structural analysis are studied by TEM and ÉDA