1,721,095 research outputs found
A note on the consistency of the maximum likelihood estimator under multivariate linear cluster-weighted models
Full text linkThis letter illustrates simple assumptions for proving consistency of the maximum likelihood estimator under multivariate Gaussian and Student's t linear cluster-weighted models, which allow density estimation, clustering and linear regression analysis with continuous random predictors in presence of unobserved heterogeneity
Le origini di Roma nel libro XLIII di Trogo-Giustino
No full textTrogus’ narrative on the origins of Rome (Historiae Philippicae, Book 43) has often been neglected because it has come down to us in the late epitome of Justin. But, through Justin’s compilation, it is clear that the Gaul-Vocontian author followed a special perspective, which is not comparable to the ‘Romanocentric’ view of both Dionysius of Halicarnassus and Livy, the most distinguished Augustan historians: in particular, Trogus devoted considerable attention to Roman prehistory (namely, to the Aborigines of Latium) and ended his account of Rome’s early days with the arrival of the Phoceans in Latium, at the time of Tarquin the Elder. My paper aims to analyze this narrative in detail and then evaluate its originality within the overall context of Augustan historiography
4D CAD Techniques and H&S Management
No full textThe European Client Organisations must face huge responsibilities by 92/57/EC Directive
when the Health and Safety Management System has to be built in. Moreover, Public Client Organisations are
trying, in different ways, to cope with such duties in modifying their Project Execution Plans over time so to
update project schedules and reports complying with H&S Plan-related measures. The researchers have performed
a detailed analysis which should allow Project Sponsors and Project Managers to deal with Time
Management following a safety-oriented approach
Un criterio di valutazione delle prestazioni delle funzioni di probabilità applicate alle portate di piena ed alle precipitazioni intense di elevato tempo di ritorno
No full textIn the present paper a criterion is presented to identify the probability distribution that is more suitable to model the historical series of the annual maxima of peak flood discharges and of rainfall depths for a given duration with special reference to high return period estimates. This method is based on the analysis of a great amount of data referring to peak flows recorded in about 12000 gauging stations distributed across the five continents and to 1 and 24 hour maximum rainfall depths recorded in about 2000 rain gauge stations located in Italy and in the USA. The proposed procedure has been applied to the probability distributions that are currently used for the analysis of the above-mentioned hydrological variables. The results provide useful information in order to select the probability distributions to be used in the formulation of regional models for the estimation of peak discharges or maximum rainfall depths for a given duration corresponding to high return periods (>100 years)
Covariance matrix estimation of the maximum likelihood estimator in multivariate clusterwise linear regression
Full text linkThe expectation-maximisation algorithm is employed to perform maximum likelihood estimation in a wide range of situations, including regression analysis based on clusterwise regression models.A disadvantage of using this algorithm is that it is unable to provide an assessment of the sample variability of the maximum likelihood estimator. This inability is a consequence of the fact that the algorithm does not require deriving an analytical expression for the Hessian matrix, thus preventing from a direct evaluation of the asymptotic covariance matrix of the estimator. A solution to this problem when performing linear regression analysis through a multivariate Gaussian clusterwise regression model is developed. Two estimators of the asymptotic covariance matrix of the maximum likelihood estimator are proposed. In practical applications their use makes it possible to avoid resorting to bootstrap techniques and general purpose mathematical optimisers. The performances of these estimators are evaluated in analysing small simulated and real datasets; the obtained results illustrate their usefulness and effectiveness in practical applications. From a theoretical point of view, under suitable conditions, the proposed estimators are shown to be consistent
Modelli probabilistici per la stima delle portate di piena di elevato tempo di ritorno
No full textThe present paper describes the results of a regional analysis of peak flood flows carried out on the basis of the historical series recorded in more than 12000 gauging station distributed across the five continents; the regionalization procedure has been performed by means of suitable standardizations of the peak discharges. If the site-to-site variability of the statistical properties of peak flows is described in terms of the variability of the first two order moments - and therefore of the average and of the coefficient of variation CV - this approach leads to the MG model, introduced by the writers in previous papers. Accounting also for the variability of the third order moment - and therefore of the coefficient of skewness g - a new probabilistic model (generalized MG model) has been obtained. With respect to the other probability distributions considered in the paper, this model provides a better interpolation of the empirical frequency distributions of the peak discharges in the range of high return periods, especially for high values of CV and g. In the same respect, also the original MG model performs better than the probability distributions that are currently used for the analysis of peak flows. Moreover, the peak discharges obtained from the empirical absolute maxima of the standardized variables can be regarded as upper bounds to be used for the design of flood control structures in the presence of particularly high risk level (e.g. dam spillways or embankments to protect nuclear sites)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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