Search results for "Serie"
showing 10 items of 1270 documents
Estrategias para mejorar la calidad de las separaciones en cromatografía líquida de fase inversa
2015
La Memoria de Tesis Doctoral propone estrategias dirigidas a mejorar la separación de mezclas que muestran una resolución cromatográfica extraordinariamente baja, en las condiciones usuales de elución, mediante cromatografía líquida de alta eficacia (HPLC, high-performance liquid chromatography). La HPLC es actualmente la técnica analítica de separación más extendida, debido a su amplio campo de aplicación, fiabilidad, robustez y sensibilidad. Lamentablemente, la eficacia que proporciona suele ser inferior a la conseguida en cromatografía de gases, electroforesis capilar y otras técnicas de electromigración, lo que representa una limitación para el análisis de muestras complejas. Los estudi…
Analisi e modelli statistici per serie storiche economiche
2020
Il testo presenta una rassegna di analisi e modelli statistici per serie storiche economiche con riferimento ai metodi maggiormente applicati a livello professionale. La trattazione è corredata da ampia analisi empirica con riferimento al software R e Python.
Introducing the DYNAMICS framework of moment-to-moment development in achievement motivation
2022
This article introduces a new theoretical and psychometric framework describing moment-to-moment development and inter-dependencies of achievement motivation in terms of the situated expectancy-value theory, by introducing dynamical systems concepts into this line of research. As a first empirical example of a study using this framework, we examined whether task values, costs, and success expectancies measured in a learning situation (time point t) predicted themselves and each other at the next situation (t + 1; 27 min later) within a weekly university lecture. Situational task values, expectancies, and costs were assessed using the experience sampling method in 155 university teacher trai…
"Everybody lies". Éthique médicale, communication médecin-patient et House M.D. : une approche didactique.
2019
Medical ethics is based on the Hippocratic Oath, whose principles of respect and benevolence have been integrated and updated in the official texts that govern the rights and duties of the medical community, including the Helsinki Declaration on Bioethics and the Code of Ethics for Medical Practice (Gold et al. 1996). The doctor-patient relationship is at the heart of medical practice and may be associated with ethical issues when announcing a diagnosis, for example; this implies that practitioners must master communication skills in accordance with medical ethics. Kurtz & al. have written the Calgary-Cambridge Referenced Observation Guides with the aim of enabling (future) professionals to…
Modeling foreign exchange market activity around macroeconomic news: Hawkes-process approach
2015
We present a Hawkes-model approach to the foreign exchange market in which the high-frequency price dynamics is affected by a self-exciting mechanism and an exogenous component, generated by the pre-announced arrival of macroeconomic news. By focusing on time windows around the news announcement, we find that the model is able to capture the increase of trading activity after the news, both when the news has a sizable effect on volatility and when this effect is negligible, either because the news in not important or because the announcement is in line with the forecast by analysts. We extend the model by considering noncausal effects, due to the fact that the existence of the news (but not…
Noise Reduction and Gap Filling of fAPAR Time Series Using an Adapted Local Regression Filter
2014
Time series of remotely sensed data are an important source of information for understanding land cover dynamics. In particular, the fraction of absorbed photosynthetic active radiation (fAPAR) is a key variable in the assessment of vegetation primary production over time. However, the fAPAR series derived from polar orbit satellites are not continuous and consistent in space and time. Filtering methods are thus required to fill in gaps and produce high-quality time series. This study proposes an adapted (iteratively reweighted) local regression filter (LOESS) and performs a benchmarking intercomparison with four popular and generally applicable smoothing methods: Double Logistic (DLOG), sm…
ICA and stochastic volatility models
2016
We consider multivariate time series where each component series is an unknown linear combination of latent mutually independent stationary time series. Multivariate financial time series have often periods of low volatility followed by periods of high volatility. This kind of time series have typically non-Gaussian stationary distributions, and therefore standard independent component analysis (ICA) tools such as fastICA can be used to extract independent component series even though they do not utilize any information on temporal dependence. In this paper we review some ICA methods used in the context of stochastic volatility models. We also suggest their modifications which use nonlinear…
Wiener-Granger Causality in Network Physiology with Applications to Cardiovascular Control and Neuroscience
2016
Since the operative definition given by C. W. J. Granger of an idea expressed by N. Wiener, the Wiener–Granger causality (WGC) has been one of the most relevant concepts exploited by modern time series analysis. Indeed, in networks formed by multiple components, working according to the notion of segregation and interacting with each other according to the principle of integration, inferring causality has opened a window on the effective connectivity of the network and has linked experimental evidences to functions and mechanisms. This tutorial reviews predictability improvement, information-based and frequency domain methods for inferring WGC among physiological processes from multivariate…
Sistemi di tariffe di cubatura per le fustaie di pino d'Aleppo, pino laricio e pino domestico della Sicilia
2009
Obiettivo del presente lavoro e la messa a punto di sistemi di tariffe validi per la cubatura delle masse legnose dei principali soprassuoli di conifere della Sicilia: in particolare, i sistemi proposti si basano sull’elaborazione delle serie di inquadramento delle relazioni ipsodiametriche per il pino domestico, il pino d’Aleppo e il pino laricio. Per ciascuna specie e stato studiato l’andamento della distribuzione dei valori ipsodiametrici, risultato ben rappresentato da una forma funzionale di tipo semilogaritmico utilizzabile come «curva guida» delle serie di inquadramento delle relazioni ipsodiametriche. Adottando l’inclinazione stimata in base alla curva guida e adattando le singole s…
Optical turbulence measurements and channel modeling of an indoor Free Space Optics link (Versione estesa)
2014
In this work, we propose an indoor experimental set-up able to generate several optical turbulence conditions in a Free Space Optics link. Using this set-up, we prove the effectiveness of an irradiance time-series generator based on the Gamma-Gamma model and able to predict the irradiance fluctuations at the receiver, under both weak and moderate turbulence conditions.