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Arbitrary shape clustering via NMF factorization
No full textOrganizing data into clusters is a key task for data mining problems. In this paper we address the problem of arbitrarily shaped clustering of points belonging to a linear space. A model based on the Euclidean distance is assumed to define the similarity among the points. An algorithm, based on the symmetric nonnegative matrix factorization (NMF) of the similarity matrix, is proposed. The main contribution of our approach consists in the merging technique of the clusters which exploits information already contained in the matrix obtained by NMF. Extensive experimentation shows that the proposed algorithm is effective and robust also for noisy data
Misura indiretta della deformazione delle rotaie del bacino n.1 dell\u27INSEAN: correzione in tempo reale della misura delle immersioni per le prove in assetto libero
Get PDFIn the present report we analyzed the deformation of the rails of the towing tank n.1 at INSEAN and its influence on the measurement of sinkage and trim for classical resistance tests. The rails of the towing Tank n.1, through the years, have undergone a deformation mainly in the terminal segment (last 100 meters). This deformation (of order of few millimeters) makes very problematic the measurement with the model in fixed conditions, but also affects the measurement of trim and, mainly, sinkage in free conditions. In particular, it influences the measurement of the submersion at bow and stern due to the changing distance between carriage and water surface during the run. The introduced error is a function of the carriage position along the basin. It is important to remark that the maximum deformation is about 3 mm and mostly regards the end of the rails, while for the initial segment of the rails (up to 200 meters) the deformation is lower than 1 mm. The compromise is to limit the tests with the model in fixed condition at 200 meters, while for the free conditions test a correction for the submersion measurements has to be applied in order to improve the quality of data and extend the run to the rails end. A function fr(x), where x is the carriage position along the rails has been obtained by fitting the acquired data by a ultrasonic probe during a carriage run.Il presente rapporto riguarda la misura delle deformazioni delle rotaie del bacino n.1 dell\u27INSEAN e la loro influenza sulla misura degli assetti nelle prove di rimorchio in assetto libero. Le rotaie del bacino n.1 dell\u27INSEAN, nel corso degli anni, hanno subito una deformazione principalmente nel tratto finale della corsa. Tale deformazione - dell\u27ordine di pochi millimetri - rende problematiche le misure di campo in assetto bloccato, ma incide anche sulla correttezza delle misure delle immersioni per le prove in assetto libero. In particolare introduce nella misura un errore dipendente dalla posizione del carro lungo la corsa dovuto alla differente distanza delle rotaie e quindi del carro dalla superficie libera. ? da rimarcare il fatto che la massima deformazione (circa 3 mm) si ha nella parte finale della corsa, mentre nella parte centrale la deformazione ? dell\u27ordine del millimetro. Come detto, nelle prove ad assetto bloccato sarebbe problematico operare una correzione e si preferisce allo stato attuale limitare la corsa alla parte centrale del bacino, dove le deformazioni sono meno influenti sulla misura finale. D\u27altra parte la limitazione della corsa per le prove in assetto libero che sono le pi? frequenti comporterebbe un aumento delle corse importante. Per questo tipo di prove, considerando che la resistenza non ? affetta da questo errore, si ? deciso di operare una correzione della misura degli assetti in tempo reale. A partire dalla misura della distanza della superficie libera dal carro durante la corsa, ? stata sviluppata una funzione continua fr(x) in grado di descrivere, per ogni posizione x del carro, l\u27entit? della deformazione, al fine di apportare le opportune correzioni alle misure delle immersioni in tempo reale in fase di acquisizione
18F-FDG-PET correlates of cognitive impairment in ALS
Get PDFObjective: To identify the metabolic signature of the various levels of cognitive deficits in amyotrophic lateral sclerosis (ALS) using 18F-2-fluoro-2-deoxy-D-glucose-PET (18F-FDG-PET). Methods: A total of 170 ALS cases consecutively enrolled at the ALS Center of Turin underwent brain 18F-FDG-PET and were classified as displaying normal cognition (ALS-Cn; n 5 94), full-blown frontotemporal dementia (ALS-FTD; n 5 20), executive or nonexecutive cognitive impairment not fulfilling FTD criteria (ALS-Ci; n 5 37), prevalent behavioral changes (n 5 9), or nonclassifiable impairment (n 5 10) according to neuropsychological testing. Group comparisons of 18F-FDG-PET pattern were carried out among the cognitive subgroups. Results: We found a significantly reduced frontal and prefrontal metabolism in ALS-FTD as compared to ALS-Cn, while ALS-Ci showed an intermediate metabolic behavior in frontal cortex, being hypometabolic as compared to ALS-Cn, and relatively hypermetabolic as compared to ALS-FTD. Hypometabolism in frontal regions was associated in all comparisons to hypermetabolism in cerebellum, midbrain, and corticospinal tracts: the more severe the cognitive decline, the larger the size of the cluster and the statistical significance of 18F-FDG uptake differences. Conclusions: This study demonstrated in a large cohort of patients with ALS a continuum of frontal lobe metabolic impairment reflecting the clinical and anatomic continuum ranging from pure ALS, through ALS with intermediate cognitive deficits, to ALS-FTD, and showing that patients with intermediate cognitive impairment display a characteristic metabolic pattern. Since 18F-FDG-PET allows us to estimate the cerebral lesion load in vivo in neurodegenerative diseases, it might be helpful to investigate in ALS its association with neuropsychological testing along the disease course to disclose the early metabolic signature of possible cognitive impairment
Decline of Neuropsychological Abilities in a Large Sample of Patients with Multiple Sclerosis: A Two-Year Longitudinal Study
No full textObjective: In this longitudinal study, we monitored two large groups of multiple sclerosis (MS) patients and healthy controls (HC) for 2 years, with the aim of comparing their neuropsychological profile over time. Method: Three hundred and twenty-two patients with MS and 303 HC were administered the Brief Repeatable Battery of Neuropsychological tests (BRB-N); neuropsychiatric measures were also administered. Two follow-ups were scheduled at 1 and 2 years, respectively. Results: A linear mixed model (LMM) with random intercept was run by considering participants\u27 performance on each test of the BRB-N at the three assessment points (baseline and follow-ups) as the within-subjects variable, and group (patients and controls) as the between-subjects factor. The interaction term was statistically significant for the tests: Symbol Digit Modalities test (SDMT) (p D 0.044), Paced Auditory Serial Addition test (PASAT) (p D 0.011) and Word List Generation (WLG) (p < 0.001), whereas for the PASAT-3 approached statistical significance (p D 0.05). In addition, a LMM with random intercept was also run by identifying three groups (controls, relapsingremitting course of MS (i.e. RR-MS), and prog-MS). The interaction term was statistically significant for: PASAT-3 (p D 0.017), PASAT-2 (p D 0.0026), and WLG (p D 0.0022). Conclusions: Our results corroborate on a very large scale evidence that the abilities tapped by the tasks SDMT, PASAT and WLG are particularly sensitive to MS, and further extend this issue by showing that these abilities are likely to be more sensitive than others to the progression of the disease, as compared to HC
Presenza e distribuzione di batteri antibiotico-resistenti nelle acque del Lago Maggiore: triennio 2013-2015
No full textNot availableRicerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 2015 e rapporto triennale 2013-2015. Presenza e distribuzione di batteri antibiotico-resistenti nelle acque del Lago Maggiore: triennio 2013-2015
Caratterizzazione tassonomica e funzionale della fauna ittica nel Lago Maggiore con particolare riferimento alla competizione per le risorse alimentari e alle specie alloctone invasive di recente comaparsa
No full textNot availableRicerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 2015 e rapporto triennale 2013-2015. Caratterizzazione tassonomica e funzionale della fauna ittica nel Lago Maggiore con particolare riferimento alla competizione per le risorse alimentari e alle specie alloctone invasive di recente comaparsa. Composizione della comunit? ittica del Lago Maggiore: abbondanze assolute e relative; distribuzione verticale; caratterizzazione della comunit? ittica. Sovrapposizione nella nicchia trofica
Indagini su DDT e sostanze pericolose nell\u27ecosistema del Lago Maggiore. Programma 2013-2015. Rapporto annuale 2015 e finale 2013-2015. Presentazione
No full textNot availablePresetazione del volume "Indagini su DDT e sostanze pericolose nell\u27ecosistema del Lago Maggiore. Programma 2013-2015. Rapporto annuale 2015 e finale 2013-2015"
How does climate change affect the response of cyanobacteria to nutrients?
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