Search results for "regression"
showing 10 items of 2619 documents
Investigating semi-hard cheese aroma: Relationship between sensory profiles and gas chromatography-olfactometry data
2012
Abstract The purpose of this study was to investigate semi-hard cheese aroma by explaining sensory characteristics of cheese by gas chromatography–olfactometry (GC–O) data obtained via intensity ratings. Sensory (13 odour attributes) and GC–O profiles obtained by trained panels were carried out on seven non-processed semi-hard cheeses. Intensity scores for significant sensory attributes and significant odour-active compounds were analysed by partial least squares to determine correlations between these datasets. A total of nine sensory attributes and 15 odour-active molecules significantly discriminated between the cheeses. There were strong correlations (89% of the sensory data was explain…
Identification of compounds responsible for the odorant properties of aromatic caramel
2012
Aromatic caramel results from the heat treatment of sugars under specific temperature conditions. Because of its richness in aroma compounds and its pleasant organoleptic properties, caramel is widely used in the food industry. However, the composition of the volatile odorant fraction has not been completely elucidated. The aim of this work was thus to identify the volatile odorant compounds responsible for caramel sensory properties using a multivariate statistical technique. Four aromatic caramels differing in terms of their carbohydrate composition and cooking process were chosen. Odorant compounds were screened by gas chromatography–olfactometry (GC-O) and identified by GC–mass spectrom…
Determination of lecithin and soybean oil in dietary supplements using partial least squares-Fourier transform infrared spectroscopy.
2008
Lecithin and soybean oil in dietary supplements were determined by Fourier transform infrared spectrometry transmission measurements in dichloromethane in combination with a partial least squares (PLS) regression. Two different PLS models were developed, using 16 synthetic mixtures of analytes in dichloromethane, making measurements in the spectral range from 931.8 to 1252.3 cm(-1) for lecithin and from 911.4 to 1246.9 cm(-1) and 1695.3 to 1774.5 cm(-1) for soybean oil. Seven products from the Spanish market with lecithin concentrations between 21.1% and 99.1% and soybean oil concentrations between 0% and 37.2% were analyzed by the proposed method and the data was compared to a chromatograp…
Simultaneous Kinetic Determination of Carbamate Pesticides after Derivatization withp-Aminophenol by Using Partial Least Squares
1996
Abstract A method has been developed for the fast spectrophotometric determination of propoxur, carbaryl, and ethiofencarb in water samples using injection analysis in the stopped-flow mode. The method is based on the reaction between p -aminophenol and the phenolic compounds obtained from the pesticides, after a previous hydrolysis with 0.05 M NaOH at room temperature for 15 min. The partial least-squares treatment of the spectrophotometry kinetic data provides a simultaneous determination of the three carbamate pesticides assayed with a relative accuracy error lower than 5% in complex mixtures also containing formetanate, which is only partially hydrolyzed under the experimental condition…
Relationship status and respiratory diseases: an analysis on a general population sample
2021
Background: Very few studies have examined whether marital/relationship status affects respiratory diseases. Objective: Assess the association of relationship status (Rstatus: domestic partnership/civil union/marriage, cohabitation with non-partners, being single) with current (CA) and past asthma (PA), allergic (AR) and non-allergic rhinitis (NAR), and chronic bronchitis (CB). Methods: Data were collected in the frame of GEIRD, a population-based, multicase-control survey. Among 2531 subjects (age 21–86, female 50%) who underwent standardized interviews, skin prick and lung function tests, 575 cases of CA, 268 cases of PA, 968 cases of AR, 462 cases of NAR, 265 cases of CB without airflow …
Factors influencing inclusion in digestive cancer clinical trials: A population-based study
2015
Inclusion in a randomized therapeutic trial represents an optimal therapeutic strategy.To determine the influence of demographic characteristics and deprivation on the enrolment of patients in digestive cancer clinical trials.Between 2004 and 2010, 4632 patients were recorded by the Burgundy Digestive Cancer Registry. According to a balancing score, the 136 patients included in a clinical trial were matched with 272 patients who met the eligibility criteria for trials. Deprivation was measured by the ecological European deprivation index. A conditional multivariate logistic regression was performed.Patients aged over 75 years were significantly less likely to be included in clinical trials …
Adaptive trial design: a general methodology for censored time to event data.
2008
Adaptive designs allow a clinical trial design to be changed according to interim findings without inflating type I error. The Inverse Normal method can be considered as an adaptive generalization of classical group sequential designs. The use of the Inverse Normal method for censored survival data was demonstrated only for the logrank statistic. However, the logrank statistic is inefficient in the presence of nuisance covariates affecting survival. We demonstrate, how the Inverse Normal method can be applied to Cox regression analysis. The required independence between test statistics of the different stages of the trial can be obtained by two different approaches. One is using the indepen…
An Extension of the DgLARS Method to High-Dimensional Relative Risk Regression Models
2020
In recent years, clinical studies, where patients are routinely screened for many genomic features, are becoming more common. The general aim of such studies is to find genomic signatures useful for treatment decisions and the development of new treatments. However, genomic data are typically noisy and high dimensional, not rarely outstripping the number of patients included in the study. For this reason, sparse estimators are usually used in the study of high-dimensional survival data. In this paper, we propose an extension of the differential geometric least angle regression method to high-dimensional relative risk regression models.
Regularized Regression Incorporating Network Information: Simultaneous Estimation of Covariate Coefficients and Connection Signs
2014
We develop an algorithm that incorporates network information into regression settings. It simultaneously estimates the covariate coefficients and the signs of the network connections (i.e. whether the connections are of an activating or of a repressing type). For the coefficient estimation steps an additional penalty is set on top of the lasso penalty, similarly to Li and Li (2008). We develop a fast implementation for the new method based on coordinate descent. Furthermore, we show how the new methods can be applied to time-to-event data. The new method yields good results in simulation studies concerning sensitivity and specificity of non-zero covariate coefficients, estimation of networ…
Análisis de la evolución de la línea de costa entre Alcossebre y Orpesa a partir de fotografía aérea (1956-2015)
2019
[ES] El artículo presenta un análisis de la evolución de la línea de costa entre Alcossebre y Orpesa, a partir de fotografías aéreas y ortofotografías, entre 1956 y 2015. La digitialización de 12 líneas de costa ha permitido calcular los cambios netos y máximos, así como la tasa de cambio entre los diferentes años. Los resultados muestran una costa recesiva, con una gran variabilidad espacio-temporal. Conviven sectores con crecimiento sostenido provocado por la acción antrópica (deriva arriba de los espigones y regeneraciones de playa) o causas naturales (prominencias costeras), con otros claramente erosivos (deriva abajo de espigones). Además, el análisis de las isobatas del estrán sumergi…