Windowed Green Function Method for Nonuniform Open-Waveguide Problems

This contribution presents a novel Windowed Green Function (WGF) method for the solution of problems of wave propagation, scattering and radiation for structures which include open (dielectric) waveguides, waveguide junctions, as well as launching and/or termination sites and other nonuniformities. Based on use of a "slow-rise" smooth-windowing technique in conjunction with free-space Green functions and associated integral representations, the proposed approach produces numerical solutions with errors that decrease faster than any negative power of the window size. The proposed methodology bypasses some of the most significant challenges associated with waveguide simulation. In particular the WGF approach handles spatially-infinite dielectric waveguide structures without recourse to absorbing boundary conditions, it facilitates proper treatment of complex geometries, and it seamlessly incorporates the open-waveguide character and associated radiation conditions inherent in the problem under consideration. The overall WGF approach is demonstrated in this paper by means of a variety of numerical results for two-dimensional open-waveguide termination, launching and junction problems.Comment: 16 Page

Perfect state transfer, graph products and equitable partitions

We describe new constructions of graphs which exhibit perfect state transfer on continuous-time quantum walks. Our constructions are based on variants of the double cones [BCMS09,ANOPRT10,ANOPRT09] and the Cartesian graph products (which includes the n-cube) [CDDEKL05]. Some of our results include: (1) If $G$ is a graph with perfect state transfer at time $t_{G}$, where t_{G}\Spec(G) \subseteq \ZZ\pi, and $H$ is a circulant with odd eigenvalues, their weak product $G \times H$ has perfect state transfer. Also, if $H$ is a regular graph with perfect state transfer at time $t_{H}$ and $G$ is a graph where t_{H}|V_{H}|\Spec(G) \subseteq 2\ZZ\pi, their lexicographic product $G[H]$ has perfect state transfer. (2) The double cone $\overline{K}_{2} + G$ on any connected graph $G$, has perfect state transfer if the weights of the cone edges are proportional to the Perron eigenvector of $G$. This generalizes results for double cone on regular graphs studied in [BCMS09,ANOPRT10,ANOPRT09]. (3) For an infinite family \GG of regular graphs, there is a circulant connection so the graph K_{1}+\GG\circ\GG+K_{1} has perfect state transfer. In contrast, no perfect state transfer exists if a complete bipartite connection is used (even in the presence of weights) [ANOPRT09]. We also describe a generalization of the path collapsing argument [CCDFGS03,CDDEKL05], which reduces questions about perfect state transfer to simpler (weighted) multigraphs, for graphs with equitable distance partitions.Comment: 18 pages, 6 figure

Oocyte production in the early postpartum cow

The postpartum period has been the focus of numerous studies; however, there is no information available relating to oocyte production in early postpartum cows. Ovaries of early postpartum cows were stimulated with FSH to produce follicular development and oocytes. The objectives of these studies were: (1) to evaluate the use of FSH for oocyte production in early postpartum beef cows, (2) to evaluate follicular response and oocyte quality of beef cows treated with FSH shortly after calving, (3) to evaluate FSH for oocyte production in early postpartum dairy cows, (4) to evaluate responses of FSH-treated, early postpartum beef cows in a transvaginal ultrasound-guided oocyte aspiration (TUGA) experiment using polyvinylpyrrolidone as the vehicle for FSH in a single dose plus energy supplementation and/or bovine somatotropin treatment, and (5) to evaluate if a single dose of GnRH could modify LH secretion in beef cows at day 5 and day 30 postpartum. In each of 4 experiments, TUGA was used to harvest oocytes from the FSH-stimulated donor cow ovaries. It was demonstrated that early postpartum cows did respond to exogenous FSH treatment with good follicular development and produced quality oocytes shortly after parturition. Harvested oocytes were subjected to IVF procedures. The number of follicles (\u3e5 mm) aspirated, number of oocytes, recovery rate, number that cleaved, number of blastocysts developing from cleaved embryos, and blastocyst production rate per donor was: 19.4, 8.8, 64%, 4.3, 1.4 and 32.3%, respectively, for cows treated with FSH and oocytes harvested between day 5 and 20 postpartum. The number of follicles aspirated per donor at day 25 and 35 postpartum was 20.4 for the FSH-treated group, resulting in 12.9 oocytes (recovery rate, 63%). It was determined that a single FSH injection could stimulate the ovaries of the early postpartum cow as early as day 10 postpartum with a follicular response of 17.5 follicles and 11 oocytes recovered per cow (recovery rate, 69%). Furthermore, live calves were obtained from harvested oocytes from FSH-treated cows in the early postpartum period. In summary, TUGA should be considered as an alternative tool for obtaining oocytes for embryo production from early postpartum cows

Windowed Green Function method for layered-media scattering

This paper introduces a new Windowed Green Function (WGF) method for the numerical integral-equation solution of problems of electromagnetic scattering by obstacles in presence of dielectric or conducting half-planes. The WGF method, which is based on use of smooth windowing functions and integral kernels that can be expressed directly in terms of the free-space Green function, does not require evaluation of expensive Sommerfeld integrals. The proposed approach is fast, accurate, flexible and easy to implement. In particular, straightforward modifications of existing (accelerated or unaccelerated) solvers suffice to incorporate the WGF capability. The mathematical basis of the method is simple: the method relies on a certain integral equation posed on the union of the boundary of the obstacle and a small flat section of the interface between the penetrable media. Numerical experiments demonstrate that both the near- and far-field errors resulting from the proposed approach decrease faster than any negative power of the window size. In the examples considered in this paper the proposed method is up to thousands of times faster, for a given accuracy, than a corresponding method based on the layer-Green-function.Comment: 17 page

Incomunicacion y Soledad: Evolucion de Un Tema Existencialista en la Obra de Ernesto Sabato

La literatura de Ernesto Sábato parte de una cosmovisión existencialista que incorpora como elemento fundamental la reflexión sobre la soledad y la incomunicación del hombre. Entre su primera novela, El túnel, y la última, Abaddón el exterminador, se advierte una evolución en el tratamiento del tema, evolución que ya es posible detectar en libros intermedios como Sobre héroes y tumbas. El nihilismo característico de la posguerra mundial (El túnel, 1948) dio paso a esa "metafísica de la esperanza" concretada en 1961 (Sobre héroes y tumbas) e intelectualizada en 1974 (Abaddón el exterminador). El marco de inquietudes en el que se mueven los personajes de Sábato es en el fondo idéntico, pero el análisis de ese cuarto de siglo de historia individual (la de un creador que concibe la novela como forma de indagación metafísica profunda) y también colectiva (la de una sociedad cuyas preocupaciones experimentan unos cambios a los que el escritor no puede permanecer ajeno), desvela a los ojos del lector la modificación del planteamiento de Sábato por lo que se refiere a la soledad y la incomunicación: no hay salida en El túnel, se habla de esperanza en Sobre héroes y, finalmente, se acepta al otro en Abaddón, casi seguro punto final de un ciclo novelístico tan desasosegador como lúcido.Ernesto Sábato 's literature is born from an existentialist perspective that incorporáis as basic element the reflection about the man's solitude and incommunication. An evolution in the treatment of the subject is perceptible between his first novel, El túnel, and the last, Abaddón el exterminador, including intermediate books as Sobre héroes y tumbas. The nihilism of the postwar (El túnel, 1948) preceded to that "metafísica de la esperanza" concreted in 1961 (Sobre héroes y tumbas), and intellectualized in 1974 (Abaddón el exterminador). The frame of preoccupations in Sábato's personages is identic, but the analysis of those twenty five years of individual history and, too, collective, shows the change in the writer's conception about the solitude and the incommunicatio

GIS based models for optimisation of marine cage aquaculture in Tenerife, Canary Islands

This study focused on the optimisation of offshore marine fish-cage farming in Tenerife, Canary Islands. The main objective was to select the most suitable sites for offshore cage culture. This is a key factor in any aquaculture operation, affecting both success and sustainability. Moreover, it can solve conflicts between different coastal activities, making a rational use of the coastal space. Site selection was achieved by using Geographical Information Systems (GIS) based models and related technology, such as satellite images and Global Positioning System (GPS), to support the decision-making process. Three different cage systems were selected and proposed for different areas around Tenerife. Finally, a particulate waste distribution model (uneaten feed and faeces) was developed, also using GIS, for future prediction of the dispersive nature of selected sites. This can reduce the number of sites previously identified as most suitable, by predicting possible environmental impacts on the benthos if aquaculture was to be developed on a specific site. The framework for spatial multi-criteria decision analysis used in this study began with a recognition and definition of the decision problem. Subsequently, 31 production functions (factors and constraints) were identified, defined and subdivided into 8 sub-models. These sub-models were then integrated into a GIS database in the form of thematic layers and later scored for standardization. At this stage, the database was verified by field sampling to establish the quality of data used. The decision maker's preferences were incorporated into the decision model by assigning weights of relative importance to the evaluation under consideration. These, together with the thematic layers, were integrated by using Multi-criteria Evaluation (MCE) and simple overlays to provide an overall assessment of possible alternatives. Finally, sensitivity analysis was performed to determine the model robustness. The integration, manipulations and presentation of the results by means of GIS-based models in this sequential and logical flow of steps proved to be very effective for helping the decision-making process of site selection in study. On the whole, this study revealed the usefulness of GIS as an aquaculture planning and management tool. Cage systems that can withstand harsh environments were found to be suitable for use over a broader area of Tenerife's coastline. Thus, the more robust self-tensioned cage (SeaStation®) could be used over a greater area than the weaker gravity cages (Corelsa®). From the 228 km2 of available area for siting cages in the coastal regions with depth of 50 m, the suitable area (sum of scores 6, 7 and 8) for siting SeaStation® cages was 61 km2, while the suitable area for SeaStation® and Corelsa® cages was 49 and 37 km2 respectively. Most of the variation between these three cage systems was found among the intermediate suitability scores. It was concluded that the biggest differences in suitable area among cage systems are between Corelsa® and SeaStation® systems, followed by differences between Corelsa® and OceanSpar® cages, and OceanSpar® and SeaStation® respectively. This variability was mostly located on the N and NNW of the island, where waves, both long and short-term, are higher

Molecular phylogenetics, evolution of sexual systems and historical biogeography of Darwin's favourite orchids (Catasetinae) and Swan orchids (Cycnoches Lindl.)

The Orchidaceae are one of the most species rich and widespread lineages among angiosperms. They have evolved numerous remarkable vegetative and reproductive traits that have allowed them to successfully adapt and diversify into a wide array of environments. More importantly, they have developed several intricate symbiotic relationships with different kinds of organisms (e.g. animals, fungi) that for centuries have attracted the attention of botanists, biologists, amateurs and naturalists. Nevertheless, despite the extensive research done so far on orchid biology and phylogenetics, very little is known about the biotic and environmental variables as well as the evolution of several key traits that seem to be linked with the successful diversification of this lineage. This dissertation is focused on three puzzling aspects of plant evolutionary biology, specifically the phylogenetic incongruence between nuclear and plastid genomes, the evolution of sexual systems, and lineage migration and isolation through time. To address these topics, I chose as a group of study the sub tribe Catasetinae, an orchid lineage including ca. 350 species restricted to the Neotropical region. They show a remarkable set of sexual systems, namely protandry and Environmental Sex Determination (ESD), that were never studied before in a phylogenetic context. My dissertation includes as well a minor part on taxonomic and floristic work devoted to other representative orchid lineages of the Neotropical flora (i.e. Epidendrum and Lepanthes). Based on vegetal material collected during field trips, my taxonomic research resulted in the description of several new species and new chorological reports contributing to the Colombian and Costa Rican Floras. Using a set of nuclear and chloroplast loci obtained from material cultivated at the Botanic Garden Munich and collected during field work in several Latin American countries, I produced a well-supported and insofar the most representatively sampled phylogeny of Catasetinae. While gathering vegetal material, I encountered several complications such as extreme scarcity of individuals and worrisome, extensive bureaucratic administrative processes to obtain collection and research permits that finally undermined my taxon sampling. By studying in detail the Catasetinae internal phylogenetic relationships independently derived from nuclear and plastid loci, I came across several well supported conflicting phylogenetic positions. Most of the traditional phylogenetic methods developed to address these conflicts aim at the inference of a species tree only. In chapter 5, I explored the utility of co-phylogenetic tools (i.e. PACo and ParaFit) to quantify the conflicts between nuclear and plastid genomes. These tools have been largely employed in host-parasite/endosymbiont studies, hence they have the power to assess the contribution of single Operational Terminal Units (OTUs) to the phylogenetic pattern observed. As a result, using the Catasetinae chloroplast and nuclear datasets and extensive simulation approaches, I demonstrate that PACo successfully detects conflicting OTUs and its performance is overall better than ParaFit. In addition, my research provided strong evidence towards the bias of input data type (i.e. phylograms and cladograms) on distance-based co-phylogenetic methods. A pipeline to execute PACo and ParaFit tools in the software R to detect conflicting sequences in either small or big datasets was designed After inferring a strongly supported phylogeny, and by carrying in-situ and ex-situ observations plus searches of specialized literature on reproductive biology, I investigated the evolution of sexual systems of Catasetinae. I relied on Ancestral State Reconstruction (ASR) approaches and Bayesian statistical frameworks (chapter 6). As a result, ASR revealed three independent gains of ESD, once in the Last Common Ancestor (LCA) of Catasetum, Cycnoches and part of Mormodes, respectively, always derived from a protandrous ancestors. In contrast, protandry appears to have evolved only once, at the LCA of Catasetum, Clowesia, Cycnoches, Dressleria and Mormodes. The last chapter of this dissertation deals with the impact of the Andean uplift, the most important orographic event in South America, on evolution of epiphytic lowland Neotropical lineages. I used as a group of study Cycnoches (a member of the Catasetinae), which includes ca. 34 species and is distributed in Neotropical lowland wet forests. To address this goal, I produced the most completely sampled phylogeny of Cycnoches, and relied on Bayesian dating and Ancestral Area Estimation (AAE) approaches. The LCA of Cycnoches lived ca. 6 million years ago (MYA) in the Amazonian region. From this area, it expanded towards Central America and Choco in multiple migrations well after main Andean mountain building episodes. In addition, stochastic character mapping showed that within-region speciation (i.e. speciation in sympatric lineages) was a key process linked to diversification and range distribution evolution in Cycnoches

Impact of genetic and environmental factors in intestinal inflammation

The gastrointestinal tract, is continuously exposed to a wide variety of stimuli, including dietary-derived metabolites, environmental compounds and the microbiota. Since these antigens can be beneficial or detrimental for the organism, proper sensing of the luminal content is essential for orchestrating both pro-inflammatory and tolerogenic immune responses on demand and therefore, ensure the establishment of intestinal homeostasis. Disruption of these mechanisms might result in inflammation, a characteristic of intestinal disorders, such as inflammatory bowel disease (IBD). How environmental triggers modulate intestinal inflammation in genetically susceptible host leading to IBD is largely unclear. The gap in knowledge around this topic is likely due to the lack of versatile in vivo models allowing the testing of a wide variety of compounds in a cost-effective manner. The aim of my doctoral thesis was to understand how intestinal inflammation is impacted by genetic factors and environmental exposures. In study I and II we analyzed how the sensing of dietary-derived metabolites modulate immune homeostasis. In study I, we found that retinoic acid receptor a (RARa) signaling in intestinal epithelial cells modulated lineage specification of secretory cells and the development of the intestinal immune system. Epithelial RARa signaling was essential for mounting protective responses against pathogen infection and maintaining intestinal homeostasis. In study II, we explored how combinatorial activation of ligand-activated transcription factors that sense dietary metabolites in vivo modulate cytokine signaling. We found that co-exposure with more than one ligand resulted in activation of the corresponding receptors, and in induction of specific cytokine profiles as a result of their interaction. In study III, we investigated how GPR35, an IBD-risk gene, modulated intestinal immune homeostasis. We found that Gpr35 deficiency in macrophages resulted in exacerbated colitis, due to low expression of genes involved in corticosterone synthesis and tumor necrosis factor (Tnf). We also identified lysophosphatidic acid as a potential GPR35 ligand that induces Tnf expression in macrophages in a GPR35-dependent manner. In study IV, we further examined how environmental factors modulate intestinal inflammation and found that perfluorooctane sulfonic acid (PFOS), an environmental pollutant, exacerbates intestinal inflammation. This was associated with impaired epithelial barrier function and systemic T cell responses. Taken together, this doctoral thesis provides insight into how environmental and genetic factors modulate immune responses contributing to the maintenance of intestinal homeostasis