Chebyshev pseudospectral method for wave equation with absorbing boundary conditions that does not use a first order hyperbolic system

Abstract The analysis and solution of wave equations with absorbing boundary conditions by using a related first order hyperbolic system has become increasingly popular in recent years. At variance with several methods which rely on this transformation, we propose an alternative method in which such hyperbolic system is not used. The method consists of approximation of spatial derivatives by the Chebyshev pseudospectral collocation method coupled with integration in time by the Runge-Kutta method. Stability limits on the timestep for arbitrary speed are calculated and verified numerically. Furthermore, theoretical properties of two methods by Jackiewicz and Renaut are derived, including, in particular, a result that corrects some conclusions of these authors. Numerical results that verify the theory and illustrate the effectiveness of the proposed approach are reported

Adaptive refinement and selection process through defect localization for reconstructing an inhomogeneous refraction index

We consider the iterative reconstruction of both the internal geometry and the values of an inhomogeneous acoustic refraction index through a piecewise constant approximation. In this context, we propose two enhancements intended to reduce the number of parameters to reconstruct, while preserving accuracy. This is achieved through the use of geometrical informations obtained from a previously developed defect localization method. The first enhancement consists in a preliminary selection of relevant parameters, while the second one is an adaptive refinement to enhance precision with a low number of parameters. Each of them is numerically illustrated

Estimación dinámica de parámetros para un modelo ecológico del Embalse Los Molinos

Fil: Rodriguez Reartes, S. B. Universidad Nacional del Sur. Consejo Nacional de Investigaciones Científicas y Técnicas. Planta Piloto de Ingeniería Química; Argentina.Fil: Estrada, V. Universidad Nacional del Sur. Consejo Nacional de Investigaciones Científicas y Técnicas. Planta Piloto de Ingeniería Química; Argentina.Fil: Bazán, R. Instituto Sup de Estudios Ambientales; Argentina.Fil: Bazán, R. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: Larrosa, N. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: Cossavella, A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: Cossavella, A. Instituto de Ciencia y Tecnología de Alimentos; Argentina.Fil: López, A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: López, A. Instituto de Ciencia y Tecnología de Alimentos; Argentina.Fil: Busso, F. Aguas Cordobesas S.A.; Argentina.Fil: Díaz, M. S. Universidad Nacional del Sur. Consejo Nacional de Investigaciones Científicas y Técnicas. Planta Piloto de Ingeniería Química; Argentina.En este trabajo, presentamos y calibramos un modelo de calidad de agua basado en primeros principios, el cual representa los procesos ecológicos a través de un complejo set de ecuaciones algebraicodiferenciales. El modelo requiere la estimación de numerosos parámetros para ajustar a las condiciones ambientales específicas del sitio en estudio. Se consideran los gradientes de las variables de estado a lo largo de la columna de agua, resultando en un sistema de ecuaciones algebraicas y diferenciales a derivadas parciales. Luego, el sistema es transformado a un sistema ordinario diferencial-algebraico (EDA) por discretización espacial del cuerpo de agua en capas horizontales. Los principales parámetros biogeoquímicos del modelo son obtenidos por resolución de un problema de estimación dinámica de parámetros, sujeto al EDA formulado. Los parámetros calculados permiten una representación apropiada de la dinámica del cuerpo de agua, como se muestra en los resultados numéricos.Fil: Rodriguez Reartes, S. B. Universidad Nacional del Sur. Consejo Nacional de Investigaciones Científicas y Técnicas. Planta Piloto de Ingeniería Química; Argentina.Fil: Estrada, V. Universidad Nacional del Sur. Consejo Nacional de Investigaciones Científicas y Técnicas. Planta Piloto de Ingeniería Química; Argentina.Fil: Bazán, R. Instituto Sup de Estudios Ambientales; Argentina.Fil: Bazán, R. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: Larrosa, N. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: Cossavella, A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: Cossavella, A. Instituto de Ciencia y Tecnología de Alimentos; Argentina.Fil: López, A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de química Industrial y Aplicada; Argentina.Fil: López, A. Instituto de Ciencia y Tecnología de Alimentos; Argentina.Fil: Busso, F. Aguas Cordobesas S.A.; Argentina.Fil: Díaz, M. S. Universidad Nacional del Sur. Consejo Nacional de Investigaciones Científicas y Técnicas. Planta Piloto de Ingeniería Química; Argentina.Otras Ingeniería Químic

Set optimization - a rather short introduction

Recent developments in set optimization are surveyed and extended including various set relations as well as fundamental constructions of a convex analysis for set- and vector-valued functions, and duality for set optimization problems. Extensive sections with bibliographical comments summarize the state of the art. Applications to vector optimization and financial risk measures are discussed along with algorithmic approaches to set optimization problems

Lagrange Duality in Set Optimization

Based on the complete-lattice approach, a new Lagrangian duality theory for set-valued optimization problems is presented. In contrast to previous approaches, set-valued versions for the known scalar formulas involving infimum and supremum are obtained. In particular, a strong duality theorem, which includes the existence of the dual solution, is given under very weak assumptions: The ordering cone may have an empty interior or may not be pointed. "Saddle sets" replace the usual notion of saddle points for the Lagrangian, and this concept is proven to be sufficient to show the equivalence between the existence of primal/dual solutions and strong duality on the one hand and the existence of a saddle set for the Lagrangian on the other hand

Comparative Live-Cell Imaging Analyses of SPA-2, BUD-6 and BNI-1 in Neurospora crassa Reveal Novel Features of the Filamentous Fungal Polarisome

A key multiprotein complex involved in regulating the actin cytoskeleton and secretory machinery required for polarized growth in fungi, is the polarisome. Recognized core constituents in budding yeast are the proteins Spa2, Pea2, Aip3/Bud6, and the key effector Bni1. Multicellular fungi display a more complex polarized morphogenesis than yeasts, suggesting that the filamentous fungal polarisome might fulfill additional functions. In this study, we compared the subcellular organization and dynamics of the putative polarisome components BUD-6 and BNI-1 with those of the bona fide polarisome marker SPA-2 at various developmental stages of Neurospora crassa. All three proteins exhibited a yeast-like polarisome configuration during polarized germ tube growth, cell fusion, septal pore plugging and tip repolarization. However, the localization patterns of all three proteins showed spatiotemporally distinct characteristics during the establishment of new polar axes, septum formation and cytokinesis, and maintained hyphal tip growth. Most notably, in vegetative hyphal tips BUD-6 accumulated as a subapical cloud excluded from the Spitzenkörper (Spk), whereas BNI-1 and SPA-2 partially colocalized with the Spk and the tip apex. Novel roles during septal plugging and cytokinesis, connected to the reinitiation of tip growth upon physical injury and conidial maturation, were identified for BUD-6 and BNI-1, respectively. Phenotypic analyses of gene deletion mutants revealed additional functions for BUD-6 and BNI-1 in cell fusion regulation, and the maintenance of Spk integrity. Considered together, our findings reveal novel polarisome-independent functions of BUD-6 and BNI-1 in Neurospora, but also suggest that all three proteins cooperate at plugged septal pores, and their complex arrangement within the apical dome of mature hypha might represent a novel aspect of filamentous fungal polarisome architecture

A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales

The Caryophyllales constitute a major lineage of flowering plants with approximately 12500 species in 39 families. A taxonomic backbone at the genus level is provided that reflects the current state of knowledge and accepts 749 genera for the order. A detailed review of the literature of the past two decades shows that enormous progress has been made in understanding overall phylogenetic relationships in Caryophyllales. The process of re-circumscribing families in order to be monophyletic appears to be largely complete and has led to the recognition of eight new families (Anacampserotaceae, Kewaceae, Limeaceae, Lophiocarpaceae, Macarthuriaceae, Microteaceae, Montiaceae and Talinaceae), while the phylogenetic evaluation of generic concepts is still well underway. As a result of this, the number of genera has increased by more than ten percent in comparison to the last complete treatments in the Families and genera of vascular plants” series. A checklist with all currently accepted genus names in Caryophyllales, as well as nomenclatural references, type names and synonymy is presented. Notes indicate how extensively the respective genera have been studied in a phylogenetic context. The most diverse families at the generic level are Cactaceae and Aizoaceae, but 28 families comprise only one to six genera. This synopsis represents a first step towards the aim of creating a global synthesis of the species diversity in the angiosperm order Caryophyllales integrating the work of numerous specialists around the world

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified