Search results for "Lasso"
showing 10 items of 110 documents
IPERSENSIBILITÀ AL GLUTINE NELL’ANZIANO. PRESENTAZIONE DI UN CASO CLINICO
2015
La celiachia è una malattia immunomediata scatenata dall’ingestione di glutine che, in soggetti geneticamente predisposti, determina un processo infiammatorio intestinale con conseguente malassorbimento e manifesta-zioni extraintestinali. Fino ad alcuni anni fa era considerata una patologia rara, tipica dell’età infantile; lo scenario epidemiologico della celiachia, oggi, è totalmente cambiato, grazie anche all’introduzione di test sierologici ad elevata sensibilità e specificità come gli anticorpi anti-endomisio (EMA) e gli anticorpi anti-transglutaminasi tissutale (tTG). Studi epidemiologici basati sull’impiego dei test sierologici hanno dimostrato che la diagnosi di celiachia viene sempr…
Propagation pattern analysis during atrial fibrillation based on sparse modeling.
2012
In this study, sparse modeling is introduced for the estimation of propagation patterns in intracardiac atrial fibrillation (AF) signals. The estimation is based on the partial directed coherence function, derived from fitting a multivariate autoregressive model to the observed signal using least-squares (LS) estimation. The propagation pattern analysis incorporates prior information on sparse coupling as well as the distance between the recording sites. Two optimization methods are employed for estimation of the model parameters, namely, the adaptive group least absolute selection and shrinkage operator (aLASSO), and a novel method named the distance-adaptive group LASSO (dLASSO). Using si…
Cyclic coordinate for penalized Gaussian graphical models with symmetry restriction
2014
In this paper we propose two efficient cyclic coordinate algorithms to estimate structured concentration matrix in penalized Gaussian graphical models. Symmetry restrictions on the concentration matrix are particularly useful to reduce the number of parameters to be estimated and to create specific structured graphs. The penalized Gaussian graphical models are suitable for high-dimensional data.
A new tuning parameter selector in lasso regression
2019
Penalized regression models are popularly used in high-dimensional data analysis to carry out variable selction and model fitting simultaneously. Whereas success has been widely reported in literature, their performance largely depend on the tuning parameter that balances the trade-off between model fitting and sparsity. In this work we introduce a new tuning parameter selction criterion based on the maximization of the signal-to-noise ratio. To prove its effectiveness we applied it to a real data on prostate cancer disease.
Bermanella marisrubri gen. nov., sp. nov., a genome-sequenced gammaproteobacterium from the Red Sea
2009
5 pages, 2 figures, 1 table
Quantile Regression Coefficients Modeling: a Penalized Approach
2018
Modeling quantile regression coefficients functions permits describing the coefficients of a quantile regression model as parametric functions of the order of the quantile. This approach has numerous advantages over standard quantile regression, in which different quantiles are estimated one at the time: it facilitates estimation and inference, improves the interpretation of the results, and is statistically efficient. On the other hand, it poses new challenges in terms of model selection. We describe a penalized approach that can be used to identify a parsimonious model that can fit the data well. We describe the method, and analyze the dataset that motivated the present paper. The propose…
Estimating Exposome Score for Schizophrenia Using Predictive Modeling Approach in Two Independent Samples: The Results From the EUGEI Study
2019
The EUGEI project was supported by the grant agreement HEALTH-F2-2010-241909 from the European Community’s Seventh Framework Programme. The authors are grateful to the patients and their families for participating in the project. They also thank all research personnel involved in the GROUP project, in particular J. van Baaren, E. Veermans, G. Driessen, T. Driesen, E. van’t Hag and J. de Nijs. Bart PF Rutten was funded by a VIDI award number 91718336 from the Netherlands Scientific Organisation.
LA SINDROME DA IPOPERISTALTISMO NEL NEONATO. A proposito di un caso clinico associato a malrotazione, intestino corto, malassorbimento
1988
Viene descritto un caso di una Sindrome caratterizzata da ipopèeristaltismo, intestino corto, malassorbimento
SPARSE INFERENCE IN COVARIATE ADJUSTED CENSORED GAUSSIAN GRAPHICAL MODELS
2021
The covariate adjusted glasso is one of the most used estimators for inferring genetic networks. Despite its diffusion, there are several fields in applied research where the limits of detection of modern measurement technologies make the use of this estimator theoretically unfounded, even when the assumption of a multivariate Gaussian distribution is satisfied. In this paper we propose an extension to censored data.