Search results for " Total"

Linear Recursive Equations, Covariance Selection, and Path Analysis

1980

Abstract By defining a reducible zero pattern and by using the concept of multiplicative models, we relate linear recursive equations that have been introduced by econometrician Herman Wold (1954) and path analysis as it was proposed by geneticist Sewall Wright (1923) to the statistical theory of covariance selection formulated by Arthur Dempster (1972). We show that a reducible zero pattern is the condition under which parameters as well as least squares estimates in recursive equations are one-to-one transformations of parameters and of maximum likelihood estimates, respectively, in a decomposable covariance selection model. As a consequence, (a) we can give a closed-form expression for t…

Robustifying principal component analysis with spatial sign vectors

2012

Abstract In this paper, we apply orthogonally equivariant spatial sign covariance matrices as well as their affine equivariant counterparts in principal component analysis. The influence functions and asymptotic covariance matrices of eigenvectors based on robust covariance estimators are derived in order to compare the robustness and efficiency properties. We show in particular that the estimators that use pairwise differences of the observed data have very good efficiency properties, providing practical robust alternatives to classical sample covariance matrix based methods.

Il monitoraggio topografico della cattedrale di Agrigento con metodi tradizionali

2014

L’oggetto del presente lavoro è il monitoraggio della cattedrale di San Gerlando di Agrigento, duomo eretto tra i secoli XI e XII, che sorge nella parte più alta della collina di Girgenti. Lo studio è significativo poiché, nel corso dei secoli la costruzione è stata soggetta a interventi di ristrutturazione e di consolidamento, resi necessari dai danni arrecati da frane che, in più occasioni, hanno coinvolto il territorio su cui essa sorge. Dal 2010 la chiesa è chiusa al culto per copiosi eventi franosi e idrogeologici che hanno allarmato ulteriormente anche la Protezione Civile. A seguito di questi eventi è stata avviata una campagna di indagini e monitoraggi con il fine della caratterizza…

Influence of total solids concentration on membrane permeability in a submerged hollow-fibre anaerobic membrane bioreactor.

2012

The main aim of this work was to study the influence of the mixed liquor total solids (MLTS) concentration on membrane permeability (K 20) in a submerged anaerobic membrane bioreactor (SAnMBR) pilot plant, which is equipped with industrial hollow-fibre membranes and treats urban wastewater. This pilot plant was operated at 33°C and 70 days of SRT. Two different transmembrane fluxes (13.3 and 10 LMH) were tested with a gas sparging intensity of 0.23 Nm 3 m -2 h -1 (measured as Specific Gas Demand referred to membrane area). A linear dependence of K 20 on MLTS concentration was observed within a range of MLTS concentration from 13 to 32 g L -1 and J 20 of 10 LMH. K 20 was maintained at sustai…

Coronary chronic total occlusions and mortality in patients with ventricular tachyarrhythmias.

2020

Aims This study sought to assess the prognostic impact of coronary chronic total occlusions (CTO) in patients presenting with ventricular tachyarrhythmias on admission. Methods and results A large retrospective registry was used, including all consecutive patients presenting with ventricular tachyarrhythmias on admission and undergoing coronary angiography from 2002 to 2016. Patients with a CTO were compared with all other patients (non-CTO) for prognostic outcomes. Statistics comprised Kaplan-Meier and Cox regression analyses. Within a total of 1,461 consecutive patients included with ventricular tachyarrhythmias on admission, a CTO was present in 20%. At midterm follow-up of 18 months, th…

Sombras en Lisboa

2000

Ultreya, suseya, Santiago!” Viaggio e spazialità ne La ballata dei pellegrini

2020

Per studiare dal punto di vista della geografia culturale alcuni aspetti del pellegrinaggio a Santiago de Compostela, in Spagna, il capitolo prende in considerazione un testo letterario, il romanzo autobiografico "La ballata dei pellegrini" della scrittrice francese Edith De La Héronnière, pubblicato per la prima volta nel 1993 e tradotto in italiano nel 2004. Il romanzo racconta l’esperienza del pellegrinaggio giacobeo effettuato dall’autrice negli anni Novanta assieme a tre compagni di viaggio partendo da un cammino francese. In particolare, attraverso l’analisi di alcune parti del testo, si indagano le modalità attraverso le quali la narrazione costruisce e descrive lo spazio fisico e si…

Spazio, potere e memoria: riflessioni di un geografo su fumetto e cartoon di propaganda

2020

Il contributo discute criticamente e da una prospettiva geografica il nesso tra propaganda, fumetti e cartoons nel periodo dei totalitarismi novecenteschi. Viene quindi esplorato il modo in cui lo spazio, reale e simbolico, sia implicato attraverso le retoriche e le dialettiche del potere, nelle dinamiche sociali, economiche e identitarie.

Canopy Architecture Appraisal by Fractal Dimension of 'Flordastar' Peach Trees Grafted onto Different Rootstocks

2007

The objective of this research was to evaluate the modification of canopy architecture of ''Flordastar'' peach (Prunus persica L. Batsch) grafted onto rootstocks with different vigour, by the use of fractal dimension (D). The hypothesis was that different vigour rootstocks are able to modify the complexity of the branching pattern and that this effect can be assessed by a geometric parameter such as the fractal dimension (D) of the 2D projection of tree branching structure. The observations were carried out in a four-year-old experimental orchard of cv. ''Flordastar'' peach trees grafted onto Ishtara, Barrier, GF677 and MrS 2/5 rootstocks. On digital pictures of leafless, dormant peach tree…

A model of adaptive decision-making from representation of information environment by quantum fields

2017

We present the mathematical model of decision making (DM) of agents acting in a complex and uncertain environment (combining huge variety of economical, financial, behavioral, and geo-political factors). To describe interaction of agents with it, we apply the formalism of quantum field theory (QTF). Quantum fields are of the purely informational nature. The QFT-model can be treated as a far relative of the expected utility theory, where the role of utility is played by adaptivity to an environment (bath). However, this sort of utility-adaptivity cannot be represented simply as a numerical function. The operator representation in Hilbert space is used and adaptivity is described as in quantu…