Search results for "TIME"

Modelling analysis of distribution network filling process during intermittent supply

2009

The paper presents the modeling results of the filling process of a water distribution network subjected to intermittent supply. The local tanks built by users for reducing their vulnerability to intermittent supply increase user water demand at the beginning of the service period and the time required for completely fill the network. Such a delicate process is responsible of the inequalities taking part among users. Users located in advantaged positions can receive water resources soon after the beginning of the service period while disadvantaged users have to wait until the network is full. Such an highly dynamic process requires ad-hoc models to be developed in order to obtain reliable r…

Kvasidegeneroituneiden steriilien neutriinojen havaitseminen

2013

We study a model of sterile neutrinos where the three ordinary active neutrinos actually consist of a superposition of an active and a sterile neutrinos forming quasidegenerate pairs. Oscillation between these pairs causes mixing between active and sterile neutrinos. Eigenmasses of the quasidegenerate pairs are very close to each other and theirs mass squared difference is of the order δm2 ~ 10^-12 eV2 or less. Such a small mass squared difference could be probed with AGN and GRB neutrinos detected in cubic kilometer size neutrino observatories. In this work, affects of different parameters and different flavours at the source to the neutrino fluxes in cases of one, two and three sterile ne…

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…

Tasapainon ja toimintakyvyn välinen yhteys nivelreumaa sairastavilla naisilla : seurantatutkimus

2013

Tausta ja tarkoitus: On yleisesti tunnettu tosiasia, että nivelreumaa sairastavien tasapaino on heikentynyt. He näyttäisivät luottavan tasapainon hallinnassa normaalia enemmän visuaaliseen informaatioon, kokevat enemmän tasapainon epävarmuutta ja kaatumisen pelkoa sekä heillä on kohonnut riski kaatumisiin verrattuna terveisiin verrokkeihin. Tämän Pro-gradu tutkielman tarkoituksena oli selvittää onko nivelreumaa sairastavien naisten tasapainossa eroa verrattuna terveisiin naisiin, tapahtuuko tasapainossa nivelreumaa sairastavilla ja terveillä verrokeilla muutoksia kuuden kuukauden seurannan aikana sekä onko nivelreumaa sairastavilla tasapainossa tapahtuvien muutosten ja itse arvioidussa toim…

Riscontro incidentale di noduli tiroidei: incidenza, aspetti B-mode e color Doppler in una popolazione adulta studiata con "real-time compound sonogr…

2006

Riscontro incidentale di noduli tiroidei: incidenza, aspetti B-mode e color Doppler in una popolazione adulta studiata con “real-time compound sonogr…

2006

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…

Etiological factors of chronic hepatitis in Italy: a 2014 national survey.

2017

Background The last Italian prevalence survey on chronic hepatitis (CH) conducted in 2001 showed that the hepatitis C virus (HCV) was the main agent associated with CH. Aim The aim of this study was to evaluate epidemiological changes in CH occurring after 13 years. Patients and methods Enrollment of 1392 CH consecutive patients referred to 16 Italian liver units in 2014 scattered all over the country (four in the North, four in the Center, four in the South, and four in the Islands) was performed. Results The mean age of the patients was 58.3 years, with a sex ratio (male/female) of 1.5. HCV infection (also with other etiologies) continues to be the most prevalent etiology (58.1%). However…

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…