Some Probabilistic Results in a Bisexual Branching Process with Immigration

2000 Mathematics Subject Classification: 60J80.A bisexual branching process with immigration of females and males is introduced. It is allowed, in each generation, that the mating function and the probability distributions associated to the offspring and the immigration may change depending on the number of progenitor couples. Relationships among the probability generating functions involved in the model and some transition and stochastic monotony properties are established.This research has been supported by the Ministerio de Ciencia y Tecnologia and the FEDER through the Plan Nacional de Investigacion Cientifica, Desarrollo e Innovaci on Tecnologica, grant BFM2003-06074

Stabilization of a class of slow-fast control systems at non-hyperbolic points

In this document, we deal with the local asymptotic stabilization problem of a class of slow fast systems (or singularly perturbed Ordinary Differential Equations). The systems studied here have the following properties: (1) they have one fast and an arbitrary number of slow variables, and (2) they have a non-hyperbolic singularity at the origin of arbitrary degeneracy. Our goal is to stabilize such a point. The presence of the aforementioned singularity complicates the analysis and the controller design. In particular, the classical theory of singular perturbations cannot be used. We propose a novel design based on geometric desingularization, which allows the stabilization of a non-hyperbolic point of singularly perturbed control systems. Our results are exemplified on a didactic example and on an electric circuit. (C) 2018 Elsevier Ltd. All rights reserved

Potenciales fuentes de aprovisionamiento para la manufactura cerámica: sitio Guayacas, Paysandú, Uruguay

En el presente trabajo se exponen los resultados obtenidos del estudio del material cerámico del sitio Guayacas, con el objetivo de identificar las fuentes de aprovisionamiento de arcillas o fangos y antiplásticos. El sitio se ubica en el departamento de Paysandú, en la zona de Guayacas, emplazado en una lomada sobre el río Daymán, 7 km al este del río Uruguay (31°30’24.58’’S y 57°56’50.88’’O). La ocupación del sitio, según fechados de TL sobre material cerámico, se encuentra entre 1471±12 y 1556±18 años DC. Mediante el análisis de DRX se identificaron potenciales sitios canteras, vinculados a aluviones modernos en las proximidades del sitio. Por otro lado, en el análisis de corte de lámina delgada se observó la presencia en las pastas de partículas biosilíceas (principalmente espículas de espongiarios) cuya concentración alertó sobre la posibilidad de su incorporación intencional como antiplástico. A los fines de contrastar dicha hipótesis, se procedió al análisis microscópico de muestras provenientes de depósitos naturales de arcilla y de colecciones de referencia de espongiarios. Asimismo, se realizaron estudios experimentales, elaborando plaquetas cerámicas con distintas combinaciones de arcillas y antiplásticos biosilíceos, procediendo a su posterior estudio microscópico. Los resultados de estos estudios sugieren una manufactura local con fuentes de aprovisionamiento de arcillas a no más de 2 km del sitio y la inclusión intencional de partículas biosilíceas en las pastas cerámicas. Este tipo de práctica ha sido ampliamente referida en la etnografía del sur de Brasil, vinculándose a propiedades tecnofuncionales de los recipientes cerámicos.The following paper presents pottery studies results from the Guayacas archaeological site. The main research goal was to identify clay or mud and temper sources. The site is located at 31°30’24.58’’S and 57°56’50.88’’W in Paysandú County, Guayacas area, over a gentle hill by the Daymán river, 7 km east of Uruguay river. According to TLD performed on pottery, the site was inhabited among 1471±12 and 1556±18 AD. DRX analysis allowed the identification of potential source areas, which are linked to modern alluvial deposits in the site surroundings. Thin section analysis highlighted the presence of biosiliceous material in the ceramic pastes (mainly sponge spicules) at an unusual concentration that suggests intentional use as a temper agent. To contrast such hypothesis, samples from natural clay deposits and sponge spicules reference collections were screened under microscopy. Simultaneously, experimental studies were carried out, making pottery tablets by combining different concentrations of clay and biosilica, and the resulting pottery was also microscopically analyzed. Obtained results allowed to infer that the whole pottery making process was locally undertook, with clay sources at no more than 2 km away from the site, and that the inclusion of sponge spicules in the raw mix was intentional. Such behavior or technical particularity has been widely reported by southern Brazil ethnographers and could be linked with pottery techno-functional attributes.Facultad de Ciencias Naturales y Muse

Potenciales fuentes de aprovisionamiento para la manufactura cerámica: sitio Guayacas, Paysandú, Uruguay

En el presente trabajo se exponen los resultados obtenidos del estudio del material cerámico del sitio Guayacas, con el objetivo de identificar las fuentes de aprovisionamiento de arcillas o fangos y antiplásticos. El sitio se ubica en el departamento de Paysandú, en la zona de Guayacas, emplazado en una lomada sobre el río Daymán, 7 km al este del río Uruguay (31°30’24.58’’S y 57°56’50.88’’O). La ocupación del sitio, según fechados de TL sobre material cerámico, se encuentra entre 1471±12 y 1556±18 años DC. Mediante el análisis de DRX se identificaron potenciales sitios canteras, vinculados a aluviones modernos en las proximidades del sitio. Por otro lado, en el análisis de corte de lámina delgada se observó la presencia en las pastas de partículas biosilíceas (principalmente espículas de espongiarios) cuya concentración alertó sobre la posibilidad de su incorporación intencional como antiplástico. A los fines de contrastar dicha hipótesis, se procedió al análisis microscópico de muestras provenientes de depósitos naturales de arcilla y de colecciones de referencia de espongiarios. Asimismo, se realizaron estudios experimentales, elaborando plaquetas cerámicas con distintas combinaciones de arcillas y antiplásticos biosilíceos, procediendo a su posterior estudio microscópico. Los resultados de estos estudios sugieren una manufactura local con fuentes de aprovisionamiento de arcillas a no más de 2 km del sitio y la inclusión intencional de partículas biosilíceas en las pastas cerámicas. Este tipo de práctica ha sido ampliamente referida en la etnografía del sur de Brasil, vinculándose a propiedades tecnofuncionales de los recipientes cerámicos.The following paper presents pottery studies results from the Guayacas archaeological site. The main research goal was to identify clay or mud and temper sources. The site is located at 31°30’24.58’’S and 57°56’50.88’’W in Paysandú County, Guayacas area, over a gentle hill by the Daymán river, 7 km east of Uruguay river. According to TLD performed on pottery, the site was inhabited among 1471±12 and 1556±18 AD. DRX analysis allowed the identification of potential source areas, which are linked to modern alluvial deposits in the site surroundings. Thin section analysis highlighted the presence of biosiliceous material in the ceramic pastes (mainly sponge spicules) at an unusual concentration that suggests intentional use as a temper agent. To contrast such hypothesis, samples from natural clay deposits and sponge spicules reference collections were screened under microscopy. Simultaneously, experimental studies were carried out, making pottery tablets by combining different concentrations of clay and biosilica, and the resulting pottery was also microscopically analyzed. Obtained results allowed to infer that the whole pottery making process was locally undertook, with clay sources at no more than 2 km away from the site, and that the inclusion of sponge spicules in the raw mix was intentional. Such behavior or technical particularity has been widely reported by southern Brazil ethnographers and could be linked with pottery techno-functional attributes.Facultad de Ciencias Naturales y Muse

Spectral performance of a zero-order liquid-crystal polymer commercial q-plate for the generation of vector beams at different wavelengths

Liquid-crystal polymer q-plates are commercial devices for generating vector beams at the design wavelength where the device exhibits half-wave (HW) retardance. Since they are not voltage addressable, the operational wavelength remains fixed. In this work we perform a broadband spectral characterization of the q-plate retardance as a function of wavelength, /(k), and identify the wavelengths with retardance values relevant for vector beam generation (p, p/2, and 3p/2). The wavelength is then used as a tuning parameter to change the device performance from a HW q-plate to a positive-QW or a negative-QW q-plate. These performances are analyzed using the Jones matrix formalism. We present a simple procedure to derive the polarization distribution of the vector beams expected at these QW wavelengths, as a superposition of the input polarization state and the output state of a HW q-plate. Experimental results using the red and blue lines of an Ar-Kr laser and an IR laser diode of 980 nm confirm the theoretical predictions. We show that for input linearly polarized light of 980 nm and 488 nm the device generates hybrid vector beams (where the ellipticity varies with the azimuthal angle), while for 647 nm pure radial vector beams with constant ellipticity are obtained. These results could extend the use of commercial q-plates for multicolour vector beam applications

Doped-iron oxide nanocrystals synthesized by one-step aqueous route for multi-imaging purposes

New doped inorganic nanocrystals (NC) consisting on iron oxide and other metal integrated into the structure have been synthesized in one-step by adapting the oxidant precipitation synthesis route for magnetite. Different metals have been chosen to confer extra and unique properties to the resulting magnetic hetero-nanostructure: Co and Gd for enhancing transversal and longitudinal relaxivities for magnetic resonance imaging and Bi and Au for achieving X-ray absorption for computed tomography imaging. Apart of that, gold optical properties are interesting for photothermal therapy and iron oxides for magnetic hyperthermia. All metals have been incorporated into the magnetite structure in different ways during the synthesis: by forming a solid solution, by modifying the surface of the NCs, or by co-crystallization with the magnetite. The nanostructure formed in each case depends on the ionic radius of the secondary metal ion and the solubility of its hydroxide that control the co-precipitation in the initial steps of the reaction. Magnetic properties and imaging capabilities of the hetero-nanostructures have been analyzed as a function of the element distribution. Due to the synergistic combination of the different element properties, these magnetic hetero-nanostructures have great potential for biomedical applications

Cyclodissipativity and Power Factor Improvement for Full Nonlinear Loads

Abstract-In recent research, a cyclodissipativity characterization of the problem of power factor compensation (PFC) for nonlinear loads with non-sinusoidal source voltage has been presented. Using this characterization the classical capacitor and inductor compensators can be interpreted in terms of energy equalization. This brief note focuses on the extension of this approach. In particular, one result is to show that power factor compensation is equivalent to a new cyclodissipativity condition. Another result is to consider general lossless linear filters as compensators and to show that the power factor is improved if and only if a certain equalization condition between the weighted powers of inductors and capacitors of the nonlinear load is ensured

Interaction between ABA and cytokinins in salinized tomato plants

Abscisic acid (ABA) and cytokinins (CKs) are phytohormones that mediate plant responses to abiotic stress and are mainly considered to be produced in roots. These two plant hormones have long been considered antagonists, but the role of this antagonism in mediating abiotic stress resistance remains unknown. In this study we have used reciprocal grafting of transgenic lines with altered hormone synthesis (ABA or CK synthesis) with the aim of assessing the importance of ABA and CK interaction in mediating plant salinity responses in tomato. Preliminary results have shown a negative effect in ABA and CK on tomato plant biomass under salinity. Results have also indicated that jasmonic acid (JA) might be involved in the negative impact on tomato growth caused by ABA and CK interaction under salt conditions.The authors thank Andrew J. Thompson, from Cranfield Univertity (UK), and Ann C. Smigocki from Molecular Plant Pathology Laboratory (EEUU) the NCED and IPT seeds sets respectively. This work was supported by CICYT AGL2011‐27996 and ROOTOPOWER (REF: 289365. FP7‐KBBE‐2011‐5 European Union)