Population dynamics of vine mealybug planococcus ficus sign. (Hemiptera-Pseudococcidae) in vineyards : Mendoza (Argentina)

Planococcus ficus Signoret es un insecto perteneciente al orden Hemiptera, familia Pseudococcidae, cuya población ha aumentado en los últimos años en Mendoza. Ataca gran variedad de hospederos y está distribuido en las principales zonas vitícolas del mundo. Su acción disminuye el vigor general de las plantas, perjudica la calidad de los frutos y las características organolépticas de los vinos elaborados con racimos infestados. El objetivo de este trabajo fue realizar estudios bioecológicos durante la temporada 2004-2005, analizando la forma de pasaje invernal y el número de generaciones anuales. Se marcaron y muestrearon plantas con los signos característicos del ataque. Se recolectó quincenalmente material vegetal infestado. En invierno: trozos de corteza. En primavera-verano: brotes, hojas y racimos. Los resultados indicaron que pasa el invierno principalmente como huevos agrupados en masas algodonosas, bajo la corteza. Se distinguieron seis generaciones, movilizándose conforme al aumento de las temperaturas hacia los brotes y hojas y, a partir de la tercera generación, a los racimos, permaneciendo en todas las partes aéreas de la planta el resto de la temporada hasta la caída de hojas. Con la disminución de las temperaturas retornó hacia la corteza del tronco para invernar.Planococcus ficus Signoret is an insect placed in the Order Hemiptera, Family Pseudococcidae. Lately high infestation levels have been reported in the vineyards of Mendoza. It feeds on a wide range of host and has been cited in many grape-growing areas. This pest can reduce the vine vigour, low the quality of the harvested grapes and affect the organoleptic features of wine. The aim of this work was study the bioecology, the distribution and seasonal behaviour of the vine mealybug. The trial was conducted on vineyards that had a history of mealybug infestation, sampling vines that showed symptoms. Have been taken pieces of bark in winter; leaves, buds and clusters in spring and summer. During the survey period, the mealybugs hibernates hide beneath barks in crevice on the trunk of the plant, as eggs laid on sac-egg. Mealybug completed six gene-rations in 2005. As soon as temperatures rise, crawlers move out onto aerial portions of the plant, settling on buds, leaves. From the 3rd generation of mealybugs clusters are reached. In fall the downward migration of the vine mealybug take place once again.Fil: Becerra, Violeta.Fil: González, Marcela.Fil: Herrera, María Eugenia.Fil: Miano, José Luis

Educación no formal. El papel del profesorado en las visitas didácticas a los museos

For decades, museums, permeated by the advantages of didactics, have been receiving an increasing number of schoolchildren. However, there are only a few studies that present the actions carried out by teachers who visit museums with their students. In this work, we want to determine to what extent teachers are involved in everything that concerns the activity of visiting a museum. Through the completion of a survey in Extremadura, we have found out that teachers carry out work before and after the visit, although there may be some bias or partiality in their answers

Comparative Analysis of Greedy Pursuits for the Order Reduction of Wideband Digital Predistorters

This paper provides a review of greedy pursuits for optimizing Volterra-based behavioral models structure and estimating its parameters. An experimental comparison of the digital predistortion (DPD) linearization performance achieved by these approaches for model-order reduction, such as compressive sampling matching pursuit (CoSaMP), subspace pursuit (SP), orthogonal matching pursuit (OMP), and the novel doubly OMP (DOMP), is presented. A benchmark of the techniques in the DPD of a commercial class AB power amplifier (PA) and a class J PA operating over a 15-MHz Long-Term Evolution (LTE) signal is presented, giving a clear overview of their pruning characteristics in terms of linearization indicators and regressor selection capabilities. In addition, the benchmark is run in a cross-validation scheme by identifying the DPD with a 30-MHz 5G-new radio (NR) signal and validating with the same signal and a 20-MHz multicarrier wideband code division multiple access (WCDMA) signal. The DOMP is shown to be a promising technique since it achieves an enhanced model-order reduction for a similar linearization performance and precision

A bivariate volterra series model for the design of power amplifier digital predistorters

(This article belongs to the Special Issue Energy-Efficient Wireless Communication Systems)The operation of the power amplifier (PA) in wireless transmitters presents a trade-off between linearity and power efficiency, being more efficient when the device exhibits the highest nonlinearity. Its modeling and linearization performance depend on the quality of the underlying Volterra models that are characterized by the presence of relevant terms amongst the enormous amount of regressors that these models generate. The presence of PA mechanisms that generate an internal state variable motivates the adoption of a bivariate Volterra series perspective with the aim of enhancing modeling capabilities through the inclussion of beneficial terms. In this paper, the conventional Volterra-based models are enhanced by the addition of terms, including cross products of the input signal and the new internal variable. The bivariate versions of the general full Volterra (FV) model and one of its pruned versions, referred to as the circuit-knowledge based Volterra (CKV) model, are derived by considering the signal envelope as the internal variable and applying the proposed methodology to the univariate models. A comparative assessment of the bivariate models versus their conventional counterparts is experimentally performed for the modeling of two PAs driven by a 30 MHz 5G New Radio signal: a class AB PA and a class J PA. The results for the digital predistortion of the class AB PA under a direct learning architecture reveal the benefits in linearization performance produced by the bivariate CKV model structure compared to that of the univariate CKV model.Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación TEC2017-82807-PFondo Europeo de Desarrollo Regiona

La intención irónica en las hipérboles y las preguntas retóricas en español

El objetivo de este estudio era evaluar el grado de intención irónica que se le atribuye a las hipérboles y a las preguntas retóricas en español. Con ese propósito, se realizaron cuatro experimentos. En los dos primeros, los participantes valoraron el grado de intención irónica que percibían en enunciados breves (hipérboles y preguntas retóricas) que escuchaban en dos condiciones diferentes: con y sin contexto. En los experimentos tres y cuatro, los sujetos realizaron dos tareas perceptivas de discriminación e identificación de entonaciones irónicas y entonación neutra en dos condiciones diferentes (contorno de f0 y frase normal). Los resultados señalaron una mejor identificación de la intención irónica de burla ligada a las hipérboles y de crítica asociada a las preguntas retóricas. También se observó un mayor peso de la información contextual frente a la prosódica, en la identificación de las intenciones irónicas de burla y crítica

Cellulases from thermophiles found by metagenomics

[Abstract] Cellulases are a heterogeneous group of enzymes that synergistically catalyze the hydrolysis of cellulose, the major component of plant biomass. Such reaction has biotechnological applications in a broad spectrum of industries, where they can provide a more sustainable model of production. As a prerequisite for their implementation, these enzymes need to be able to operate in the conditions the industrial process requires. Thus, cellulases retrieved from extremophiles, and more specifically those of thermophiles, are likely to be more appropriate for industrial needs in which high temperatures are involved. Metagenomics, the study of genes and gene products from the whole community genomic DNA present in an environmental sample, is a powerful tool for bioprospecting in search of novel enzymes. In this review, we describe the cellulolytic systems, we summarize their biotechnological applications, and we discuss the strategies adopted in the field of metagenomics for the discovery of new cellulases, focusing on those of thermophilic microorganisms.Xunta de Galicia.; ED431C2016-01

On the Optimum Number of Coefficients of Sparse Digital Predistorters: A Bayesian Approach

This work presents insights on the application of the Bayesian information criterion (BIC) to fix the optimum number of coefficients in the Volterra series applied to the modeling and linearization of power amplifiers (PAs). The BIC is transformed from a rule to be applied after selection techniques to a stopping criterion, which enables the halting of the algorithm when a condition is reached. This study reveals that the BIC is equivalent to allow a certain identification normalized mean square error (NMSE) decrease after the inclusion of a model component. Experimental results of the digital predistortion of a class J PA are provided, demonstrating the proposal applicability in the attaining of the optimum number of coefficients. A comparison is made between the results obtained when the stopping rule is applied to the hill climbing (HC) and the doubly orthogonal matching pursuit (DOMP) algorithms

An Upgraded Dual-Band Digital Predistorter Model for Power Amplifiers Linearization

Digital predistortion (DPD) based on Volterra models is commonly employed to counteract the nonlinear distortion of power amplifiers. However, when concurrent dual-band signals are transmitted, 2-D DPD models are required. In this work, upgrading of a standard dual-band model is proposed and justified using multinomial theorem. The linearization performance of the current proposal has been compared to the unextended model. Fifth generation (5G) New Radio signals have been generated to compose a dual-band signal, which later was employed as input signal at Chalmers University of Technology's RF WebLab. Using coefficient selection techniques, the most relevant regressors are shown, and the importance of the new extension is proven. Linearization results highlight the benefits of this proposal.Comisión Europea, Fondo Europeo de Desarrollo RegionalMinisterio de Economía y Competitividad TEC2017-82807-

Formal deduction of a Volterra series model for complex-valued systems

This paper demonstrates a general model for nonlinear systems with complex-valued inputs and its application to communication systems modeling. Based on Wirtinger calculus and a double Volterra series approach, the proposed representation can also be considered as a generalization of the widely linear transformation to incorporate the description of nonlinear systems. The complete structure is pruned with the assistance of a compressive-sensing algorithm in order to reduce the number of parameters. To illustrate this approach, it has been experimentally implemented to model a transmitter for OFDM signals, which includes an I/Q modulator and a power amplifier.Ministerio de Economía y Competitividad TEC2014-53103-P

Digital predistortion of power amplifiers using structured compressed-sensing Volterra series

Digital predistortion has become an attractive technique for power amplifier linearisation whose limiting factor for using Volterra series as the underlying model is its computational complexity, since the number of components rapidly grows with the non-linear order and memory. Based on a previous reference algorithm, which consists on applying the orthogonal matching pursuit for the sorting of the model components and a Bayesian information criterion for the selection of the optimum number of components, a new technique to reduce the size of the support set taking into account the structural information within a model is presented. Experimental results of the predistortion of a commercial power amplifier are given as a proof of its capabilities, showing equivalent performance to the pruning with the reference algorithm while further reducing the number of components.Ministerio de Economía y Competitividad TEC2011-23559 TEC2014-53103-