Search results for "Regression"
showing 10 items of 2619 documents
Análisis tiempo-frecuencia de la fibrilación ventricular. Estudio experimental
2006
Introduction and objectives. The analysis of frequency variability during ventricular fibrillation has yielded inconsistent results. We used an experimental model of ventricular fibrillation, with a short timescale, to analyze variations in frequency and their associated spatial distribution. Methods. Epicardial recordings of ventricular fibrillation were made in 10 perfused isolated rabbit heart preparations using a multiple electrode system (i.e., 240 unipolar electrodes). Both spectral and time-frequency analysis were used to derive the dominant frequency in the anterolateral wall of the left ventricle. Results. Linear regression analysis showed that there was a good correlation between …
Feature extraction from remote sensing data using Kernel Orthonormalized PLS
2007
This paper presents the study of a sparse kernel-based method for non-linear feature extraction in the context of remote sensing classification and regression problems. The so-called kernel orthonormalized PLS algorithm with reduced complexity (rKOPLS) has two core parts: (i) a kernel version of OPLS (called KOPLS), and (ii) a sparse (reduced) approximation for large scale data sets, which ultimately leads to rKOPLS. The method demonstrates good capabilities in terms of expressive power of the extracted features and scalability.
Comprehensive Strategy for Proton Chemical Shift Prediction: Linear Prediction with Nonlinear Corrections
2014
A fast 3D/4D structure-sensitive procedure was developed and assessed for the chemical shift prediction of protons bonded to sp3carbons, which poses the maybe greatest challenge in the NMR spectral parameter prediction. The LPNC (Linear Prediction with Nonlinear Corrections) approach combines three well-established multivariate methods viz. the principal component regression (PCR), the random forest (RF) algorithm, and the k nearest neighbors (kNN) method. The role of RF is to find nonlinear corrections for the PCR predicted shifts, while kNN is used to take full advantage of similar chemical environments. Two basic molecular models were also compared and discussed: in the MC model the desc…
Semisupervised kernel orthonormalized partial least squares
2012
This paper presents a semisupervised kernel orthonormalized partial least squares (SS-KOPLS) algorithm for non-linear feature extraction. The proposed method finds projections that minimize the least squares regression error in Hilbert spaces and incorporates the wealth of unlabeled information to deal with small size labeled datasets. The method relies on combining a standard RBF kernel using labeled information, and a generative kernel learned by clustering all available data. The positive definiteness of the kernels is proven, and the structure and information content of the derived kernels is studied. The effectiveness of the proposed method is successfully illustrated in standard UCI d…
Semisupervised Kernel Feature Extraction for Remote Sensing Image Analysis
2014
This paper presents a novel semisupervised kernel partial least squares (KPLS) algorithm for nonlinear feature extraction to tackle both land-cover classification and biophysical parameter retrieval problems. The proposed method finds projections of the original input data that align with the target variable (labels) and incorporates the wealth of unlabeled information to deal with low-sized or underrepresented data sets. The method relies on combining two kernel functions: the standard radial-basis-function kernel based on labeled information and a generative, i.e., probabilistic, kernel directly learned by clustering the data many times and at different scales across the data manifold. Th…
Sources of life satisfaction judgments in Latvia
2010
AbstractResearch indicates that life satisfaction judgments may be influenced by many different factors, but there is no clear evidence how these judgments are constructed. The purpose of this study was to examine sources of life satisfaction judgments in Latvia. Respondents (N=605) aged 18 - 70 completed self report measures of life satisfaction (SWLS), satisfaction with life domains, stressful life events, positive and negative affects (PANAS). Regression analysis shows that model including satisfaction with different life domains, positive and negative affects and number of stressful life events measures explains 53% of the variance in the overall life satisfaction. Immediately after com…
Website quality and internal business factors: An empirical investigation in the Italian wine industry
2016
Purpose The purpose of this paper is dual. The first is to assess the quality of websites of Italian wineries, using the Web Assessment Index (WAI), and compare e-commerce and e-marketing websites. The second is to verify the existence of a relationship between the website quality and business revenue, on one hand, and the characteristics of managers, on the other. Design/methodology/approach A two-step survey was carried out to respond to the aims of the study. First, a sample of wineries was contacted to capture information on both the wineries and managerial characteristics. On the basis of the observed data, a second step of the analysis was performed taking into consideration 84 winer…
Health-related correlates of psychological well-being among girls and boys 6-8 years of age: The Physical Activity and Nutrition in Children study
2018
AIM Due to limited knowledge on the differences in the correlates of psychological well-being (PSWB) between girls and boys, we compared the correlates of PSWB between primary school girls and boys. METHODS A population sample of 412 children participated in the Physical Activity and Nutrition in Children study. Parents completed a questionnaire that included 19 questions on the components of PSWB, and a PSWB score was computed. We assessed correlates of PSWB, including physical activity, sedentary behaviour, cardiorespiratory fitness, diet quality, body fat content, sleep duration, sleep disordered breathing, prevalent diseases and parental characteristics. We used logistic regression to a…
Hospitalization for self-harm during the early months of the COVID-19 pandemic in France: A nationwide retrospective observational cohort study
2021
ABSTRACT Background Little is known to date about the impact of COVID-19 pandemic on self-harm. Methods The number of hospitalizations for self-harm (ICD-10 codes X60-X84) in France from 1st January to 31st August 2020 (including a two-month confinement) was compared to the same periods in 2017–2019. Statistical methods comprised Poisson regression, Cox regression and Student's t-test, plus Spearman's correlation test relating to spatial analysis of hospitalizations. Outcomes There were 53,583 self-harm hospitalizations in France during January to August 2020. Compared to the same period in 2019, this represents an overall 8·5% decrease (Relative Risk [95% Confidence Interval] = 0·91 [0·90–…
Dental pain associated with untreated dental caries and sociodemographic factors in 5-year-old children
2020
Background The aim of this study was to assess the prevalence of dental pain and to examine its association with untreated dental caries in 5-year-old children. Material and Methods This was a cross-sectional study of 261 5-year-old children in Northeast Brazil. Parents answered questions about their socioeconomic conditions and their children's toothache. Trained dentists assessed dental caries using the decayed, missing and filled teeth (dmf-t) index. Binary logistic regression models were used to estimate the unadjusted and adjusted odds ratios (ORs) and the confidence intervals (95% CIs) for the association of dental pain with covariates. The significance level was set at five percent. …