Search results for "least square"
showing 10 items of 286 documents
Photoluminescence study of terbium-exchanged ultrastable Y zeolites: Number of species, photoluminescence decays and decay-associated spectra
2008
Terbium-exchanged ultrastable Y (USY) zeolites were investigated by using time-resolved photoluminescence spectroscopy techniques and methods. To determine the distribution of terbium species in USY zeolites together with their photoluminescence properties, several analysis methods for the time-resolved luminescence spectra were used such as the area normalization of time-resolved photoluminescence spectra, singular value decomposition, global nonlinear least squares, and the maximum entropy. Except for a questionable long lifetime, small contribution of a terbium species with lifetime of 1.9¿2.1 ms, all the experimental and analysis results converged to a two terbium species distribution w…
Maximum Likelihood Estimation and non-linear least squares fitting with Levenberg-Marquardt Algorithm implementation in FPGA devices for high resolut…
2012
This work compares two possible solutions to achieve a higher resolution in a hodoscope based on Plastic Scintillating Fibers (PSF) by obtaining the point of maximum incidence of the radioactive beam. The two fitting algorithms proposed have been tested and implemented in Field Programmable Gate Array (FPGA) devices. On one hand, a probabilistic model based on the Maximum Likelihood Estimation (MLE) and on the other hand, non-linear least-squares fit with the Levenberg-Marquardt Algorithm (LMA).
Consumer confidence: Causality links with subjective and objective information sources
2020
Abstract This study analyses the relationship of causality between consumer confidence and the economic information ecosystem from subjective (i.e., business sentiment) and objective sources (financial information from listed companies and the stock index). Our sample covers Spain from June 2011 to December 2018. Our results show that consumer confidence and economic information can exert a causality influence on each other. The results show Granger causality from IBEX35 and total assets in the financial sector and leverage of the companies in the energy sector to the consumer confidence index (CCI), in the first lag: from operating income in the telecommunications sector to the CCI in the …
Perceived Value in Tourism: A PLSPM Approach
2015
This paper examines the concept of perceived value in rural tourism referred to the specific context of Sicilian holiday farms. Herein main dimensions composing the rural tourist perceived value (RTPV) are discussed. Using Partial Least Squares Path Modelling (PLSPM) –a statistical technique especially suitable for exploratory purposes with small samples – a theoretical structural model of the multidimensional structure of RTPV is tested and the causal relationships among RTPV and its dimensions (Functional, Convenience, Emotional and Educational) and among RTPV and tourists’ satisfaction and loyalty are explored. Results from a field survey on 350 tourists give a contribution in terms of i…
Quantification and classification of high-resolution magic angle spinning data for brain tumor diagnosis.
2007
The goal of this work is to propose a complete protocol (preprocessing, processing and classification) for classifying brain tumors with proton high-resolution magic-angle spinning ((1)H HR-MAS) data. The different steps of the procedure are detailed and discussed. Feature extraction techniques such as peak integration, including also the automated quantitation method AQSES, were combined with linear (LDA) and non-linear (least-squares support vector machine or LS-SVM) classifiers. Classification accuracy was assessed using a stratified random sampling scheme. The results suggest that LS-SVM performs better than LDA while AQSES performs better than the standard peak integration feature extr…
Three-dimensional geometric morphometrics of thorax-pelvis covariation and its potential for predicting the thorax morphology: A case study on Kebara…
2020
The skeletal torso is a complex structure of outstanding importance in understanding human body shape evolution, but reconstruction usually entails an element of subjectivity as researchers apply their own anatomical expertise to the process. Among different fossil reconstruction methods, 3D geometric morphometric techniques have been increasingly used in the last decades. Two-block partial least squares analysis has shown great potential for predicting missing elements by exploiting the covariation between two structures (blocks) in a reference sample: one block can be predicted from the other one based on the strength of covariation between blocks. The first aim of this study is to test w…
Resolvin D1 and miR‐146a are independent distinctive parameters in children with moderate and severe asthma
2020
To date, a large number of mediators and biomarkers have been detected in childhood asthma, with a potential role in monitoring the disease course. Lung function evaluation through spirometry, forced oscillation technique and multiple breath washout proved its role in asthma monitoring, especially for investigating small airway impairment in children with more severe symptoms. Recently, novel specialized pro-resolving mediators, such as resolvins and lipoxins, have been recognized as crucial in promoting the resolution of lung inflammation. Increasing evidence suggests that miRNAs are crucially entailed in asthma. Partial least squares discriminant analysis (plsDA) is a modern technique for…
Prediction Accuracy of a Novel Dynamic Structure-Function Model for Glaucoma Progression
2014
Purpose To assess the prediction accuracy of a novel dynamic structure-function (DSF) model to monitor glaucoma progression. Methods Longitudinal data of paired rim area (RA) and mean sensitivity (MS) from 220 eyes with ocular hypertension or primary open-angle glaucoma enrolled in the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study were included. Rim area and MS were expressed as percent of mean normal based on an independent dataset of 91 healthy eyes. The DSF model uses centroids as estimates of the current state of the disease and velocity vectors as estimates of direction and rate of change over time. The first three visits were used to pre…
Weighted Least-Squares Likelihood Ratio Test for Branch Testing in Phylogenies Reconstructed from Distance Measures
2005
A variety of analytical methods is available for branch testing in distance-based phylogenies. However, these methods are rarely used, possibly because the estimation of some of their statistics, especially the covariances, is not always feasible. We show that these difficulties can be overcome if some simplifying assumptions are made, namely distance independence. The weighted least-squares likelihood ratio test (WLS-LRT) we propose is easy to perform, using only the distances and some of their associated variances. If no variances are known, the use of the Felsenstein F-test, also based on weighted least squares, is discussed. Using simulated data and a data set of 43 mammalian mitochondr…
Influence of Advertising on Brand Personality in The Airline Sector: The Case of Spain
2013
This article outlines the findings of a study employing a partial least squares (PLS) structural equation methodology to explore the relationship among advertising and brand personality (BP) dimension of a validated Aaker's model (1997) in the airline business. BP refers to the emotional side of brand image. It is created by all experiences of consumers with a brand. The model was validated using confirmatory factor analysis and the effect of advertising on BP has been tested using PLS. The findings suggest that advertising influences the formation of BP only in the sophistication dimension. These results invite managers in the airline companies sector to develop communication strategies to…