Clustering of concurrent flood risks via Hazard Scenarios

The study of multiple effects of a number of variables, and the assessment of the corresponding environmental risks, may require the adoption of suitable multivariate models when the variables at play are dependent, as it often happens in environmental studies. In this work, the flood risks in a given region are investigated, in order to identify specific spatial sub-regions (clusters) where the floods show a similar behavior with respect to suitable multivariate) criteria. The reason of the work is three-fold, and the outcomes have deep implications in the hydrological practice: (i) such a regionalization (as it is called in hydrology) may provide useful indications for deciding which gauge stations have a similar (stochastic) behavior; (ii) the spatial clustering may represent a valuable tool for investigating ungauged basins present in a given \u2018\u2018homogeneous\u2019\u2019 Region; (iii) the estimate of extreme design values may be improved by using all the observations collected in a cluster (instead of only single-station data). For this purpose, a Copulabased Agglomerative Hierarchical Clustering algorithm \u2013 a key tool in geosciences for the analysis of the dependence information \u2013 is proposed. The procedure is illustrated via a case study involving the Po river basin, the largest Italian one. A comparison with a previous attempt to cluster the gauge stations present in the same spatial region is also carried out. The sub-regions picked out by the clustering procedure outlined here agree with previous results obtained via heuristic hydrological and meteorological reasonings, and identify spatial areas characterized by similar flood regimes

Clustering financial time series by measures oftail dependence

We discuss two methods for clustering financial time series in extreme scenarios. The procedures are based on the calculations of two different measures of tail dependence, namely the (lower) tail dependence coefficient and the conditional Spearman\u2019s correlation. Performances of the proposed methodologies are compared via a simulation study

Clustering of financial time series in risky scenarios

A methodology is presented for clustering financial time series according to the association in the tail of their distribution. The procedure is based on the calculation of suitable pairwise conditional Spearman\u2019s correlation coefficients extracted from the series. The performance of the method has been tested via a simulation study. As an illustration, an analysis of the components of the Italian FTSE\u2013MIB is presented. The results could be applied to construct financial portfolios that can manage to reduce the risk in case of simultaneous large losses in several markets

Influence of aging and chronic heart failure on temporal dispersion of myocardial repolarization

Gianfranco Piccirillo,1 Federica Moscucci,1 Matteo Pascucci,1 Maria Antonella Pappadà,1 Gaetana D’Alessandro,1 Pietro Rossi,2 Raffaele Quaglione,1 Daniele Di Barba,1 Francesco Barillà,1 Damiano Magrì3 1Department of Cardiovascular, Respiratory, Nephrological and Geriatric Sciences, Policlinico Umberto I, “Sapienza” University of Rome, Rome, Italy; 2Division of Cardiology, S. Giovanni Calabita Fatebenefratelli Hospital, Rome, Italy; 3Department of Clinical and Molecular Medicine, Sant’Andrea Hospital, “Sapienza” University of Rome, Rome, Italy Background and purpose: QT and Tpeak-Tend (Te) intervals are associated with sudden cardiac death in patients with chronic heart failure (CHF). We studied age-dependent influence on short-term temporal dispersion of these two variables in patients with postischemic CHF. Method: We grouped 75 CHF and 53 healthy control subjects into three age subsets: ≤50 years, >50 years and ≤65 years, and >65 years. We then calculated the following indices: QT and Te variability index (QTVI and TeVI), the ratio between the short-term variability (STV) of QT or Te, and the STV of resting rate (RR) (QT/RR STV and Te/RR STV). Results: In all different age subgroups, patients with CHF showed a higher level of QTVI than age-matched control subjects (≤50 years: P < 0.0001; >50 years and ≤65 years: P < 0.05; >65 years: P <  0.05). Patients with CHF < 50 years old also had all repolarization variability indices higher than normal age-matched controls (TeVI, P < 0.05; QT/RR STV, P < 0.05; Te/RR STV, P < 0.05), whereas we did not find any difference between the two older classes of subjects. Both QTVI (r2: 0.178, P < 0.05) and TeVI (r2: 0.433, P < 0.001) were positively related to age in normal subjects, even if the first correlation was weaker than the second one. Conclusion: Our data showed that QTVI could be used in all ages to evaluate repolarization temporal liability, whereas the other indices are deeply influenced by age. Probably, the age-dependent increase in QTVI was more influenced by a reduction of RR variability reported in older normal subjects. Keywords: aging, QT variability, heart rate variability, chronic heart failure, sudden deat

Le garanzie per l'accesso al credito nella piccola media impresa

Il saggio si propone di analizzare il tema strategico dell\u2019accesso al credito bancario per le pmi e strumenti di facilitazione. Naturalmente il tema delle garanzie reali e personali costituisce l\u2019elemento fondante del ricorso al credito anche in ragione del fatto che la garanzia reale o personale , sotto il profilo delle regole di Basilea, costituisce elemento idoneo ad accrescere il merito creditizio dell\u2019impresa.. Tuttavia, stante tale inquadramento di carattere generale, lo studio ha affrontato principalmente il tema dei consorzi fidi e della relativa disciplina giuridica. Come noto il cd consorzio fidi \ue8 figura legislativamente riconosciuta in Italia dalla legge 12 agosto 1977, n.675 la cui disciplina \ue8 stata recentemente rivista dall\u2019art.13 del decreto legge n.269/2003 cos\uec come convertito dalla legge 24 novembre 2003, n.326. La peculiarit\ue0 giuridica dei consorzi fidi \ue8 quella di essere strutturalmente per l\u2019appunto consorzi costituiti da piccole e medie imprese secondo la definizione contenuta nella disciplina comunitaria in materia di aiuti di Stato a favore della PMI ma la legislazione e la dottrina esistente si sono soprattutto incentrate sulla definizione delle strutture associative utilizzabili per l\u2019attuazione di detta attivit\ue0. Rimanevano poco studiati due profili invece di assoluta rilevanza che il saggio in questione si \ue8 proposto di affrontare: l\u2019elemento della mutualit\ue0 che per certi versi pu\uf2 essere ricondotta alla mutualit\ue0 di tipo assicurativo e secondariamente l\u2019analisi degli strumenti contrattuali tramite i quali cui questi enti operano. L\u2019aspetto su cui si \ue8 incentrato il saggio in oggetto \ue8 soprattutto quello del tipo di garanzia offerta dai consorzi fidi la quale presenta due caratteri specifici: ovvero quello di avere natura di garanzia collettiva e quello di presentare un carattere mutualistico. Ci\uf2 nel senso che tali garanzie di natura personale,prestate in favore dei finanziamenti richiesti dalle imprese consociate ed erogate da banche od intermediari finanziari,vengono prestate mediante l\u2019utilizzazione a garanzia di risorse provenienti in tutto o in parte dalle imprese consorziate :Quanto alla loro qualificazione il saggio avverte circa l\u2019importanza di analizzare caso per caso i singoli statuti e regolamenti dei consorzi posto che esse costituiscono normalmente garanzie sussidiarie ,a meno che lo statuto del consorzio non affermi la natura della garanzia quale cofideiussione. E \u2018 evidente che da tali qualificazioni ne conseguono differenze di disciplina assolutamente rilevanti tra cui l\u2019esistenza o meno della surrogazione in capo al fideiussore principale che va esclusa qualora la garanzia dei consorzi fidi sia solo sussidiaria