When are signals complements or substitutes?

The paper introduces a notion of complementarity (substitutability) of two signals which requires that in all decision problems each signal becomes more (less) valuable when the other signal becomes available. We provide a general characterization which relates complementarity and substitutability to a Blackwell-comparison of two auxiliary signals. In a special setting with a binary state space and binary, symmetric signals, we find an explicit characterization that permits an intuitive interpretation of complementarity and substitutability. We demonstrate how these conditions extend to the general case. Finally, we study implications of complementarity and substitutability for information acquisition and in a second price auction

Generalized Hilbert Operators

If $g$ is an analytic function in the unit disc \D we consider the generalized Hilbert operator \hg defined by {equation*}\label{H-g} \mathcal{H}_g(f)(z)=\int_0^1f(t)g'(tz)\,dt. {equation*} We study these operators acting on classical spaces of analytic functions in \D . More precisely, we address the question of characterizing the functions $g$ for which the operator \hg is bounded (compact) on the Hardy spaces $H^p$, on the weighted Bergman spaces $A^p_\alpha$ or on the spaces of Dirichlet type $\mathcal D^p_\alpha$

Graphical identification of TAR models

This paper proposes an automatic procedure to identify Threshold Autoregressive models and specify the threshold values. The proposed procedure is based on recursive estimation of arranged autoregression. The main advantage of the proposed procedure over its competitors is that the threshold values are automatically detected. The performance of the proposed procedure is evaluated using simulations and real data.Nonlinear time series, Recursive estimation, Arranged autoregression, TAR models, Nonlinearity test

Photonic molecules for improving the optical response of macroporous silicon photonic crystals for gas sensing purposes

In this paper, we report the benefits of working with photonic molecules in macroporous silicon photonic crystals. In particular, we theoretically and experimentally demonstrate that the optical properties of a resonant peak produced by a single photonic atom of 2.6 µm wide can be sequentially improved if a second and a third cavity of the same length are introduced in the structure. As a consequence of that, the base of the peak is reduced from 500 nm to 100 nm, while its amplitude remains constant, increasing its Q-factor from its initial value of 25 up to 175. In addition, the bandgap is enlarged almost twice and the noise within it is mostly eliminated. In this study we also provide a way of reducing the amplitude of one or two peaks, depending whether we are in the two- or three-cavity case, by modifying the length of the involved photonic molecules so that the remainder can be used to measure gas by spectroscopic methods.Postprint (published version

Características clínicas y epidemiológicas de niños preescolares con asma.

El asma es una de las enfermedades crónicas más frecuentes en pediatría. Tiene alta prevalencia en nuestro medio. Nos planteamos como objetivo de este trabajo conocer el fenotipo y características clínico-epidemiológicas de los menores de 5 años que habitan en Rafaela y zona rural, además de evaluar los factores de riesgo que pudieran influir en los grupos estudiados, considerando el medio ambiente donde los niños crecen. Esto con la intención de poder establecer si existen diferencias en la positividad de los índices predictivos del asma original y del modificado entre dos grupos expuestos a distintas condiciones ambientales. Esta tesis aporta datos originales con relación al asma en un grupo etario de vulnerabilidad para esta afección. En América Latina hay muy pocos estudios publicados que analicen los aspectos que heos estudiado. Creemos que nuestros hallazgos servirán de guía para los médicos que atiendan niños asmáticos menores de 5 años en dicha región, si se considera la importancia de un análisis profundo del paciente que incluya sus costumbres y sus exposiciones ambientales. De acuerdo con estos resultados, recomendamos evaluar los factores de riesgo y aplicar el API (índice precitivo de asma), como herramienta muy útil para el diagnóstico de asma en niños menores de 5 años

Evaluation of Argentine wild sunflower biotypes for drought stress during reproductive stage

As in several regions where sunflower production has moved to areas with limiting water availability, the search for water-stress tolerant genotypes has been intensified. Helianthus annuus ssp. annuus L. constitutes a potential genetic resource because it has naturalized in the semi-arid zone of central Argentina. The assessment of these genetic materials for water deficit tolerance is of interest because they may represent a source of genes for drought tolerance, useful to sunflower breeding. Drought resistant genotypes should be achieved using easily identified phenotypic traits. Parameters like leaf area are widely used to characterize the performance under stress. Leaf temperature is an easily measured physiological parameter that allows an indirect estimate of plant transpiration and is well correlated with water availability. Relative water content indicates the ability to retain water from the soil and expresses plant osmotic adjustment ability. Specific leaf area is a morphological parameter related to leaf thickness. The objectives of this study were to evaluate the drought tolerance of Argentine wild sunflower biotypes and identify morphological and physiological traits expressing differences between stressed biotypes. Wild biotypes were evaluated during three years in the experimental field of the Agronomy Department, Universidad Nacional del Sur, Argentina. Groups of 10-15 plants of each biotype were evaluated under two water conditions, drought (deficit supply) with drip irrigation to cover a half of the potential evapotranspiration during flowering, or with optimal water supply. Soil surface was covered with black polyethylene to exclude rainwater. Wild sunflower comprised five biotypes collected from different habitats in the semiarid region of Argentina. Crosses between the wild biotypes and inbred lines were also included every year. Inbred lines and a commercial hybrid (DK4000) were used as controls. Recorded traits were: plant height, stem diameter, petiole length, leaf area, leaf number, head number and reproductive surface. Leaf parameters were: relative water content (RWC), specific leaf area (SLA), canopy temperature (CT), and chlorophyll content (SPAD). A susceptibility index (SI) was obtained to compare the performance under water stress with that obtained in optimal conditions. Biotype evaluation and parameter characterization were performed separately for each year because water stress levels were different. Wild sunflower responses to water stress were different for all parameters among biotypes, except for plant height and petiole length. Wild biotypes had better RWC and lower SLA than cultivated biotypes. Under water stress wild biotypes showed higher values and greater range of RWC and SPAD than cultivated sunflower. Susceptibility index showed that leaf area of wild sunflower biotypes had lower stress susceptibility than cultivated sunflowers. Nevertheless, wild biotypes showed increased susceptibility to the remaining plant morpho-physiological parameters. RWC and CT had a significant relationship in wild sunflower biotypes under water stress. Drought tolerant type identification was complex because of the complex responses among parameters. Wild biotypes might have a physiological mechanism which allows higher RCA than cultivated sunflower under drought stress. The lower SLA under water deficit could be attributed to a greater leaf thickness and could be related with RCA. Lower leaf area reduction under stress in wild sunflower is an interesting trait that might be used to improve cultivated sunflower. As the RWC is related with CT under stress in wild biotypes, this trait evaluation allows the fast examination of a high number of plants. The assessment of Argentina wild sunflower biotypes for traits associated with drought tolerance has not yet been done. Their identification could increase sunflower crop yield under drought in semiarid regions.Fil: Fernández Moroni, Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Fraysse, M.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Presotto, Alejandro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Cantamutto, Miguel Ángel. Instituto Nacional de Tecnología Agropecuaria; Argentin