Search results for "multivariate analysi"
showing 10 items of 1084 documents
Prevalence and characteristics of antidepressant drug prescriptions in older Italian patients.
2012
ABSTRACTBackground: During last few decades, the proportion of elderly persons prescribed with antidepressants for the treatment of depression and anxiety has increased. The aim of this study was to evaluate prevalence of antidepressant prescription and related factors in elderly in-patients, as well as the consistency between prescription of antidepressants and specific diagnoses requiring these medications.Methods: Thirty-four internal medicine and four geriatric wards in Italy participated in the Registro Politerapie SIMI–REPOSI study during 2008. In all, 1,155 in-patients, 65 years or older, were enrolled. Prevalence of the use of antidepressants was calculated at both admission and dis…
Exposure to mercury among 9-year-old Spanish children: Associated factors and trend throughout childhood
2019
Mercury is considered a neurotoxicant and human exposure occurs mainly from the consumption of marine species. We aimed to describe total mercury concentrations (THg) and associated factors in 9-year old children, as well as to explore the trend in THg from 4 to 9 years of age. The study population consisted of 9-year-old children participating in the INMA (Environment and Childhood) birth cohort study in Valencia, Spain (n = 405, 2013–2014). THg in hair samples was measured by atomic absorption spectrometry at the age of 4 and 9 years. Sociodemographic and dietary data was obtained through questionnaires. Multiple linear regression was used to explore the association between THg and covari…
gllvm: Fast analysis of multivariate abundance data with generalized linear latent variable models inr
2019
The work of J.N. was supported by the Wihuri Foundation. The work of S.T. was supported by the CRoNoS COST Action IC1408.F.K.C.H. was also supported by an ANU cross disciplinary grant.
Use of Leaf and Fruit Morphometric Analysis to Identify and Classify White Mulberry (Morus alba L.) Genotypes
2018
Digital image analysis and multivariate data analysis were used in this study to identify a set of leaf and fruit morphometric traits to discriminate white mulberry (Morus alba L.) cultivars. The trial was conducted using three- to five-year-old potted cuttings of several white mulberry cultivars. 32 leaf morphometric descriptors were recorded in 2011 and 2012 from 11 mulberry cultivars using image analysis of scanned leaves, whereas six fruit descriptors were recorded in 2011 from nine mulberry cultivars. Linear discriminant analysis (LDA) was used to identify a subset of measured variables that could discriminate the cultivars in trial. Biplot analysis, followed by cluster analysis, was p…
Helminth associations in white-toothed shrews Crocidura russula (Insectivora : Soricidae) from the Albufera Natural Park, Spain
2004
The helminths of 218 white-toothed shrews from 29 sites in 2 biotopes in the Albufera Natural Park (Valencia, Spain) were examined from July 1990 to August 1991. An association analysis of helminths occurring at a prevalence of more than 4% was carried out for 4 species of cestodes located in the intestine (Hymenolepis pistillum, H. scalaris, H. tiara, and Pseudhymenolepis redonica) and 3 species of nematodes (Pseudophysaloptera sp. located in the stomach, Stammerinema rhopocephala larvae in the intestine and abdominal cavity, and Porrocaecum sp. in the thoracic and abdominal cavities). Bivariate (species pairs) versus multivariate analyses (associations within the entire set of species) we…
Cinderella's helping pigeons of the microbial world: The potential of testate amoebae for identifying cryptotephra
2016
Cryptotephra (particles <125μm) is a key record for monitoring past and current volcanic activity. However, its extraction from the host sediment and analysis is often long and difficult because of its small size. Finding a simple method to extract cryptotephra from environmental samples would therefore make its analysis much easier. We hypothesized that arcellinid testate amoebae may hold such a potential. These free-living shelled protists are among the earliest microorganisms to colonize volcanic tephra, and build their shell by agglutinating minerals from their environment. We analyzed by X-ray Spectrometry the mineral signature of tephra from the 2011 Puyehue-Cordon Caulle Volcanic Com…
Efficient estimation of generalized linear latent variable models.
2019
Generalized linear latent variable models (GLLVM) are popular tools for modeling multivariate, correlated responses. Such data are often encountered, for instance, in ecological studies, where presence-absences, counts, or biomass of interacting species are collected from a set of sites. Until very recently, the main challenge in fitting GLLVMs has been the lack of computationally efficient estimation methods. For likelihood based estimation, several closed form approximations for the marginal likelihood of GLLVMs have been proposed, but their efficient implementations have been lacking in the literature. To fill this gap, we show in this paper how to obtain computationally convenient estim…
Discrimination of common defects in loquat fruit cv. ‘Algerie’ using hyperspectral imaging and machine learning techniques
2021
Abstract Loquat (Eriobotrya japonica L.) is an important fruit for the economy of some regions of Spain that is very susceptible to mechanical damage and physiological disorders. These problems depreciate its value and prevent it from being exported. Visible (VIS) and near infrared (NIR) hyperspectral imaging was used to discriminate between external and internal common defects of loquat cv. ‘Algerie’. Two classifiers, random forest (RF) and extreme gradient boost (XGBoost), and different spectral pre-processing techniques were evaluated in terms of their capacity to distinguish between sound and defective features according to three approaches. In the first approach the fruit pixels were c…
Variational Approximations for Generalized Linear Latent Variable Models
2017
Generalized linear latent variable models (GLLVMs) are a powerful class of models for understanding the relationships among multiple, correlated responses. Estimation, however, presents a major challenge, as the marginal likelihood does not possess a closed form for nonnormal responses. We propose a variational approximation (VA) method for estimating GLLVMs. For the common cases of binary, ordinal, and overdispersed count data, we derive fully closed-form approximations to the marginal log-likelihood function in each case. Compared to other methods such as the expectation-maximization algorithm, estimation using VA is fast and straightforward to implement. Predictions of the latent variabl…
Co-inertia multivariate approach for the evaluation of anthropogenic impact on two commercial fish along Tyrrhenian coasts
2019
Abstract Aliphatic hydrocarbon levels were determined by the GC/MS technique in fish livers of Engraulis encrasicolus (Ee) and Trachurus trachurus (Tt), collected from a particular area of the Mediterranean Sea, called GSA 10, which is located exactly in Tyrrhenian Sea between Campania coast and North Sicily coast. The aim was to evaluate their potential use as specific bioindicators towards this class of contaminants. Both Tt and Ee are considered to be pollution monitoring bioindicators, due to their dominance in marine communities and economic fishing interest. Ee showed a higher tendency to bioaccumulate TAHs, due to the lower quantity of fatty acids in liver tissues with respect to Tt.…