Algoritmos rápidos para computar estimadores robustos

El método más comunmente usado para estimar los coeficientes de una regresión lineal es el de mínimos cuadrados. Este método que es óptimo en el caso de errores distribuídos normalmente, es muy sensible a la presencia de outliers. Para remediar ese problema se han desarrollado otros métodos de estimación llamados métodos robustos, los cuales se ven poco afectados por la presencia de datos atípicos. Una medida de la robustez de un estimador es su punto de ruptura. Entre los estimadores de regresión robustos se encuentran los LTS, LMS y los S estimadores. Estos estimadores son equivariantes por transformaciones afines, de regresión, y de escala y además tiene un alto punto de ruptura. El inconveniente que presenta su calculo es que requiere muchas horas de computadora. Rouseeuw y Van Driessen desarrollaron un algoritmo, llamado Fast -LTS, que mejora la velocidad de cálculo del estimador de mínimos cuadrados podados. El objetivo de este trabajo es desarrollar un nuevo algoritmo, análogo al Fast-LTS, para computar S estimadores. Del mismo modo que el algoritmo desarrollado por Rouseeuw, este nuevo algoritmo está basado en el mejoramiento local de los nuevos estimadores iniciales. Esto permite una significativa reducción del número de candidatos requeridos para obtener una buena aproximación de la solución óptima. Se ha realizado un estudio de simulación que ha mostrado que los S estimadores calculados con el algoritmo Fast-S, son comparativamente mejores a los estimadores LTS calculados con el algoritmo Fast-LTS. Algunas de las ventajas del nuevo algoritmo son: 1) Menor porcentaje de muestras afectadas por los datos atípicos. 2) Menor error cuadrático medio. 3) Menor tiempo de cómputo.Regression analysis is an important statistical tool that is applied in most sciences. The purpose of regression analysis is to fit equations to observed variables. The most commonly regression technique is the least squares method, generally adopted because of tradition and easier computation. However these method is very sensitive to the presence of atypical points in the sample. An observation is an atypical point or outlier if it does not follow the model. To remedy this problem the robust mothods have been developed that are not so easuly affected by outliers. One mesure of robustness of an estimate is its breakdown point. Heuristically, the breakdown point is the minimun fraction of arbitrary outliers that can take the estimate beyond any limit. The breakdown point as an asymptotic concept has been introduced by Hampel (1971). Donoho and Huber (1983) gave the corresponding finite sample notion. A desirable property for regression estimates is that the estimate be equivariant with respect to affine, regression and scale transformations. Estimates are computationally expensive, and the corresponding algorithms become unfasible for moderately large number of regressors. In this thesis we propose an algorithm for computing S-estimates, analogous to the algorithm of Rousseeuw and Van Driessen (Fast-LTS) to improve the computational speed of the LTS-estimate. The new algorithm, that we call "fast-S", is based on a "local improvement" step of the re-sampling initial candidates. This allows a substantial reduction of the number of candidates requiered to obtain a good approximation to the optimal solution. We performed a simulation study wich shows that S-estimators computed with the fast-S algorithm compare favourably to the LTS estimator computed with the fast-LTS algorithm.Fil: Ambrosio, Beatriz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Eficiência técnica dos produtores de leite no Projeto de Assentamento Fruta D’Anta, João Pinheiro – MG

Este trabalho objetivou avaliar a eficiência técnica entre os produtores de leite da no PA Fruta D’Anta, no município de João Pinheiro, MG, no ano de 2006. Utilizou-se como instrumental analítico a Análise Envoltória de Dados (DEA), contando com uma amostra de 22 produtores assentados. Os resultados obtidos evidenciam que uma proporção significativa dos produtores são ineficientes tecnicamente. Observou-se, também, que todos os produtores ineficientes estão trabalhando sob retornos crescentes à escala, o que permite afirmar que estes poderiam aumentar seu lucro mais que proporcional quando aumentada à produção.-----------------The main objective of this paper was to evaluate the technical efficiency in 22 milk producers in the PA FrutaD’Anta, in the council de João Pinheiro, MG, during the period of 2006. The technical efficiency was evaluted through the Data Envelopment Analysis (DEA) technique. The results obtained show that there are still a significant proportion of inefficient farms. It was also observed that the inefficient producers are working on crescent returns to scale that admit so affirm that these could increase yours lucre more that proportional increasing yours production.assentamentos rurais, DEA, produção de leite, Minas Gerais, rural settlement, milk production, DEA. Minas Gerais, Livestock Production/Industries,

Construcción de políticas públicas en relación al agua de la provincia Neuquén: Procesos participativos generados a partir de la ley de alerta hídrica ambiental

El presente artículo intenta demostrar los avances generados en cuanto a la protección de los recursos hídricos a partir de la sanción de la Ley 3076/17 y la posterior conformación del Comité de Alerta Hídrico de la provincia del Neuquén, República Argentina. Se destacan en esto los avances logrados en cuanto a la participación ciudadana y el aporte activo de los diferentes actores y sectores que componen el Comité.Fil: Membribe, Anahí. Universidad Nacional del Comahue; ArgentinaFil: Perez, German Gabriel. Universidad Nacional del Comahue. Instituto Patagónico de Estudios de Humanidades y Ciencias Sociales. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Patagónico de Estudios de Humanidades y Ciencias Sociales; ArgentinaFil: Ambrosio, Miriam Beatriz. Universidad Nacional del Comahue; Argentin

La degradación de la tierra en el Departamento Minas (Provincia de Neuquén), a través de la evaluación geoecológica de los paisajes

El presente trabajo analiza la relación existente entre el tamaño y uso de la tierra y la degradación en un sector del Departamento Minas, al Noroeste de la Provincia de Neuquén, Argentina (Figura Nº 1). El mismo forma parte de un proyecto mas amplio, cuyo objetivo es el estudio de las causas que generan la degradación de la tierra en la totalidad del Noroeste provincial. Sobre la magnitud de este problema conviene recordar que más de la tercera parte de la superficie terrestre del planeta es árida y en ella el proceso de desertización y degradación se ha intensificado en los últimos decenios. Según las Naciones Unidas, este problema amenaza el porvenir de más de 785 millones de personas, o sea casi el 20% de la población mundial. Siguiendo con el informe de FAO, también se estima que entre 50.000 y 70.000 km2 de tierras útiles dejan de producir cada año por estos motivos. Argentina en general y la Patagonia en particular, no son ajenos a este problema ya que aproximadamente el 75% del territorio nacional se encuentra afectado por crecientes condiciones de aridez. En la Patagonia argentina, el 90% de la superficie (unos 780.000 km2) presenta signos de degradación y de esta superficie, un 30% se encuentra afectado por procesos erosivos severos y graves con tendencia a agravarse.

WOOD VINEGAR: CHEMICAL CHARACTERISTICS, PHYTOTOXIC EFFECTS, AND IMPACTS ON GREENHOUSE GAS EMISSIONS

ABSTRACT: Wood vinegar has been used for over a century as a fertilizer and antimicrobial agent, but its impacts on ecosystems are poorly understood; further research is necessary to understand its chemical characteristics and avoid negative impacts. This study assessed the chemical characteristics, phytotoxicity, potential cytotoxicity, and greenhouse gas emissions of wood vinegar made from slow pyrolysis in a hot-tail kiln using cambara wood (Qualea sp.). Incubation experiments with varying concentrations of wood vinegar were established in samples of clayey, loamy, and sandy tropical soils, measuring CO2, N2O, and CH4 over a 120-day period. Toxic effects on the germination, root tips, and meristematic cells of Lactuca sativa were also assessed. The findings confirmed that wood vinegar can function as a chemical fertilizer  and pesticide, as well as a co-solvent for chemicals, particularly in agricultural and pharmaceutical applications, while the phytotoxicity indicated that this substance must be diluted for agricultural uses. Wood vinegar was seen to inhibit CO2 and N2O emissions from loamy and clayey soils, but this effect was not observed in sandy soil. Wood vinegar also blocked cell division in some dilutions, but at concentrations of less than 0.5% it did not present a potential risk to the environment or plants in general. Keywords: pyroligneous acid; biomass; pyrolysis; residues; cytotoxicity.   Vinagre de madeira: características químicas, efeitos fitotóxicos e impactos nas emissões de gases   RESUMO: O vinagre de madeira é usado há mais de um século como fertilizante e agente antimicrobiano, mas seus impactos nos ecossistemas são pouco conhecidos; pesquisas são necessárias para entender suas características e evitar impactos negativos. Este estudo avaliou as características químicas, fitotoxicidade, potencial citotoxicidade e emissões de gases do vinagre de madeira obtido a partir de pirólise lenta em forno de cauda quente utilizando madeira de cambará (Qualea sp.). Experimentos de incubação com concentrações variadas do vinagre foram estabelecidos em amostras de solos tropicais argilosos, textura média e arenosos, medindo CO2, N2O e CH4 durante 120 dias. Efeitos tóxicos no modelo Lactuca sativa também foram avaliados. Os resultados confirmaram que o vinagre de madeira pode funcionar como fertilizante químico e pesticida, bem como um co-solvente para produtos químicos, principalmente em aplicações agrícolas e farmacêuticas, enquanto a fitotoxicidade indicou que essa substância deve ser diluída para uso agrícola. O vinagre de madeira parece inibir as emissões de CO2 e N2O de solos argilosos e argilosos, mas esse efeito não foi observado em solo arenoso. O vinagre de madeira também bloqueou a divisão celular em algumas diluições, mas em concentrações inferiores a 0,5% não apresentou risco potencial ao meio ambiente ou às plantas em geral. Palavras-chave: ácido pirolenhoso; biomassa; pirólise; resíduos; citotoxicidade.ABSTRACT: Wood vinegar has been used for over a century as a fertilizer and antimicrobial agent, but its impacts on ecosystems are poorly understood; further research is necessary to understand its chemical characteristics and avoid negative impacts. This study assessed the chemical characteristics, phytotoxicity, potential cytotoxicity, and greenhouse gas emissions of wood vinegar made from slow pyrolysis in a hot-tail kiln using cambara wood (Qualea sp.). Incubation experiments with varying concentrations of wood vinegar were established in samples of clayey, loamy, and sandy tropical soils, measuring CO2, N2O, and CH4 over a 120-day period. Toxic effects on the germination, root tips, and meristematic cells of Lactuca sativa were also assessed. The findings confirmed that wood vinegar can function as a chemical fertilizer  and pesticide, as well as a co-solvent for chemicals, particularly in agricultural and pharmaceutical applications, while the phytotoxicity indicated that this substance must be diluted for agricultural uses. Wood vinegar was seen to inhibit CO2 and N2O emissions from loamy and clayey soils, but this effect was not observed in sandy soil. Wood vinegar also blocked cell division in some dilutions, but at concentrations of less than 0.5% it did not present a potential risk to the environment or plants in general. Keywords: pyroligneous acid; biomass; pyrolysis; residues; cytotoxicity.   Vinagre de madeira: características químicas, efeitos fitotóxicos e impactos nas emissões de gases   RESUMO: O vinagre de madeira é usado há mais de um século como fertilizante e agente antimicrobiano, mas seus impactos nos ecossistemas são pouco conhecidos; pesquisas são necessárias para entender suas características e evitar impactos negativos. Este estudo avaliou as características químicas, fitotoxicidade, potencial citotoxicidade e emissões de gases do vinagre de madeira obtido a partir de pirólise lenta em forno de cauda quente utilizando madeira de cambará (Qualea sp.). Experimentos de incubação com concentrações variadas do vinagre foram estabelecidos em amostras de solos tropicais argilosos, textura média e arenosos, medindo CO2, N2O e CH4 durante 120 dias. Efeitos tóxicos no modelo Lactuca sativa também foram avaliados. Os resultados confirmaram que o vinagre de madeira pode funcionar como fertilizante químico e pesticida, bem como um co-solvente para produtos químicos, principalmente em aplicações agrícolas e farmacêuticas, enquanto a fitotoxicidade indicou que essa substância deve ser diluída para uso agrícola. O vinagre de madeira parece inibir as emissões de CO2 e N2O de solos argilosos e argilosos, mas esse efeito não foi observado em solo arenoso. O vinagre de madeira também bloqueou a divisão celular em algumas diluições, mas em concentrações inferiores a 0,5% não apresentou risco potencial ao meio ambiente ou às plantas em geral. Palavras-chave: ácido pirolenhoso; biomassa; pirólise; resíduos; citotoxicidade

European Commission Initiative on Breast Cancer: Concept document

The European Commission Initiative on Breast Cancer (ECIBC) is aimed at ensuring and harmonising breast cancer services quality across European countries. It is coordinated by Commission’s Joint Research Centre, under the supervision of the Directorate-General Health and Food Safety. This document describes the background of the initiative, its general goals and objectives, and its foreseen outcomes.JRC.F.1-Health in Societ

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file