Degree of multicollinearity and variables involved in linear dependence in additive-dominant models

The objective of this work was to assess the degree of multicollinearity and to identify the variables involved in linear dependence relations in additive-dominant models. Data of birth weight (n=141,567), yearling weight (n=58,124), and scrotal circumference (n=20,371) of Montana Tropical composite cattle were used. Diagnosis of multicollinearity was based on the variance inflation factor (VIF) and on the evaluation of the condition indexes and eigenvalues from the correlation matrix among explanatory variables. The first model studied (RM) included the fixed effect of dam age class at calving and the covariates associated to the direct and maternal additive and non-additive effects. The second model (R) included all the effects of the RM model except the maternal additive effects. Multicollinearity was detected in both models for all traits considered, with VIF values of 1.03 - 70.20 for RM and 1.03 - 60.70 for R. Collinearity increased with the increase of variables in the model and the decrease in the number of observations, and it was classified as weak, with condition index values between 10.00 and 26.77. In general, the variables associated with additive and non-additive effects were involved in multicollinearity, partially due to the natural connection between these covariables as fractions of the biological types in breed composition.

A random linear functional approach to efficiency bounds

This paper suggests a method for obtaining efficiency bounds in models containing either only infinite-dimensional parameters or both finite- and infinite-dimensional parameters (semiparametric models). The method is based on a theory of random linear functionals applied to the gradient of the log-likelihood functional and is illustrated by computing the lower bound for Cox's regression model

High capacity robust audio watermarking scheme based on FFT and linear regression

Peer-reviewed

Linear prediction application for modelling the relationships between a large number of stand characteristics of Norway spruce stands

Abstract

Comments on "On resistor-induced thermal noise in linear circuits"

Correspondència referida a l'article de R. Giannetti, publicat ibid. vol.49 p.87-88

Linear and nonlinear terrain deformation maps from a reduced set of interferometric SAR images

In this paper, an advanced technique for the generation of deformation maps using synthetic aperture radar (SAR) data is presented. The algorithm estimates the linear and nonlinear components of the displacement, the error of the digital elevation model (DEM) used to cancel the topographic terms, and the atmospheric artifacts from a reduced set of low spatial resolution interferograms. The pixel candidates are selected from those presenting a good coherence level in the whole set of interferograms and the resulting nonuniform mesh tessellated with the Delauney triangulation to establish connections among them. The linear component of movement and DEM error are estimated adjusting a linear model to the data only on the connections. Later on, this information, once unwrapped to retrieve the absolute values, is used to calculate the nonlinear component of movement and atmospheric artifacts with alternate filtering techniques in both the temporal and spatial domains. The method presents high flexibility with respect to the required number of images and the baselines length. However, better results are obtained with large datasets of short baseline interferograms. The technique has been tested with European Remote Sensing SAR data from an area of Catalonia (Spain) and validated with on-field precise leveling measurements.

Interação de proteínas Cry1 e Vip3A de Bacillus thuringiensis para controle de lepidópteros-praga

O objetivo deste trabalho foi avaliar a suscetibilidade das lagartas Anticarsia gemmatalis (Lepidoptera: Erebidae) e Chrysodeixis includens (Lepidoptera: Noctuidae) às proteínas Cry1 e Vip3A, bem como determinar se há a interação entre essas proteínas no controle das duas espécies. Bioensaios com as proteínas isoladas e em combinações foram realizados, e as concentrações letais CL50 e CL90 foram estimadas para cada condição. As proteínas Cry1Aa, Cry1Ac e Vip3Af foram as mais efetivas no controle de A. gemmatalis, enquanto Cry1Ac, Vip3Aa e Vip3Af foram mais efetivas no de C. includens. As proteínas Cry1Ac e Cry1Ca causaram maior inibição do desenvolvimento das larvas sobreviventes à CL50, em ambas as espécies. Combinações entre Vip3A e Cry1 apresentam efeito sinérgico no controle das espécies e a combinação Vip3Aa+Cry1Ea destaca-se no controle de A. gemmatalis e C. includens. Essas proteínas combinadas são promissoras na construção de plantas piramidadas, para o controle simultâneo das pragas.

Extratos de Piper marginatume Azadirachta indica no controle de Colletotrichum scovillei em pimentão

O objetivo deste trabalho foi avaliar o efeito de extratos de capeba (Piper marginatum) e nim (Azadirachta indica) sobre o fungo Colletotrichum scovillei e determinar o componente mais ativo no controle pós-colheita da antracnose em pimentão. A atividade de extratos metanólicos das folhas (P.marginatum e A. indica) e das sementes (A. indica) a 0, 125, 250, 500, 1.000 e 2.000 ppm, na inibição do crescimento micelial de C. scovillei in vitro foram avaliadas. O extrato metanólico de folhas de P.marginatum foi o mais ativo e, consequentemente, foi submetido ao fracionamento biomonitorado ("bioassay-guided fractionation"). Esse processo rendeu 10 frações majoritárias, obtidas por cromatografia líquida de alta performance, das quais a fração à concentração de 1,5 ppm inibiu o desenvolvimento de C. scovillei de forma mais eficiente do que o fungicida mancozeb.