5 resultados para Multiple Additive Regression Trees (MART)
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
Questa tesi descrive alcuni studi di messa a punto di metodi di analisi fisici accoppiati con tecniche statistiche multivariate per valutare la qualità e l’autenticità di oli vegetali e prodotti caseari. L’applicazione di strumenti fisici permette di abbattere i costi ed i tempi necessari per le analisi classiche ed allo stesso tempo può fornire un insieme diverso di informazioni che possono riguardare tanto la qualità come l’autenticità di prodotti. Per il buon funzionamento di tali metodi è necessaria la costruzione di modelli statistici robusti che utilizzino set di dati correttamente raccolti e rappresentativi del campo di applicazione. In questo lavoro di tesi sono stati analizzati oli vegetali e alcune tipologie di formaggi (in particolare pecorini per due lavori di ricerca e Parmigiano-Reggiano per un altro). Sono stati utilizzati diversi strumenti di analisi (metodi fisici), in particolare la spettroscopia, l’analisi termica differenziale, il naso elettronico, oltre a metodiche separative tradizionali. I dati ottenuti dalle analisi sono stati trattati mediante diverse tecniche statistiche, soprattutto: minimi quadrati parziali; regressione lineare multipla ed analisi discriminante lineare.
Resumo:
Background: Clinical trials have demonstrated that selected secondary prevention medications for patients after acute myocardial infarction (AMI) reduce mortality. Yet, these medications are generally underprescribed in daily practice, and older people are often absent from drug trials. Objectives: To examine the relationship between adherence to evidence-based (EB) drugs and post-AMI mortality, focusing on the effects of single therapy and polytherapy in very old patients (≥80 years) compared with elderly and adults (<80 years). Methods: Patients hospitalised for AMI between 01/01/2008 and 30/06/2011 and resident in the Local Health Authority of Bologna were followed up until 31/12/2011. Medication adherence was calculated as the proportion of days covered for filled prescriptions of angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs), β-blockers, antiplatelet drugs, and statins. We adopted a risk set sampling method, and the adjusted relationship between medication adherence (PDC≥75%) and mortality was investigated using conditional multiple logistic regression. Results: The study population comprised 4861 patients. During a median follow-up of 2.8 years, 1116 deaths (23.0%) were observed. Adherence to the 4 EB drugs was 7.1%, while nonadherence to any of the drugs was 19.7%. For both patients aged ≥80 years and those aged <80 years, rate ratios of death linearly decreased as the number of EB drugs taken increased. There was a significant inverse relationship between adherence to each of 4 medications and mortality, although its magnitude was higher for ACEIs/ARBs (adj. rate ratio=0.60, 95%CI=0.52–0.69) and statins (0.60, 0.50–0.72), and lower for β-blockers (0.75, 0.61–0.92) and antiplatelet drugs (0.73, 0.63–0.84). Conclusions: The beneficial effect of EB polytherapy on long-term mortality following AMI is evident also in nontrial older populations. Given that adherence to combination therapies is largely suboptimal, the implementation of strategies and initiatives to increase the use of post-AMI secondary preventive medications in old patients is crucial.
Resumo:
The instability of river bank can result in considerable human and land losses. The Po river is the most important in Italy, characterized by main banks of significant and constantly increasing height. This study presents multilayer perceptron of artificial neural network (ANN) to construct prediction models for the stability analysis of river banks along the Po River, under various river and groundwater boundary conditions. For this aim, a number of networks of threshold logic unit are tested using different combinations of the input parameters. Factor of safety (FS), as an index of slope stability, is formulated in terms of several influencing geometrical and geotechnical parameters. In order to obtain a comprehensive geotechnical database, several cone penetration tests from the study site have been interpreted. The proposed models are developed upon stability analyses using finite element code over different representative sections of river embankments. For the validity verification, the ANN models are employed to predict the FS values of a part of the database beyond the calibration data domain. The results indicate that the proposed ANN models are effective tools for evaluating the slope stability. The ANN models notably outperform the derived multiple linear regression models.
Resumo:
This research aims to discover the virome diversity and composition in Fusarium poae and Fusarium proliferatum collections, characterize the mycovirus that may have an effect on host pathogenicity to provide potential materials for the biological control of Fusarium spp. pathogens. Next-Generation Sequencing (NGS) analysis of 30 F. poae isolates revealed an extreme diversity of mycoviruses. Bioinformatic analysis shows that contigs associated with viral genome belong to the families: Hypoviridae, Mitoviridae, Partitiviridae, Polymycoviridae, proposed Alternaviridae, proposed Fusagraviridae, proposed Fusariviridae, proposed Yadokariviridae, and Totiviridae. The complete genomes of 12 viruses were obtained by assembling contigs and overlapping cloning sequences. Moreover, all the F. poae isolates analyzed are multi-infected. Fusarium poae partitivirus 1 appears in all the 30 strains, followed by Fusarium poae fusagravirus 1 (22), Fusarium poae mitovirus 2 (18), Fusarium poae partitivirus 3 (16), and Fusarium poae mitovirus 2 and 3 (11). Using the same approach, the virome of F. proliferatum collections resulted in lower diversity and abundance. The identified mycoviruses belong to the family Mitoviridae and Mymonaviridae. Interestingly, most F. proliferatum isolates are not multi-infected. The complete genomes of four viruses were obtained by assembling contigs and overlapping cloning sequences. By multiple liner regression of the virome composition and growth rate of 30 F. poae, Fusarium poae mitovirus 3 is significantly correlated with the growth rate among F. poae collection. Furthermore, the principal component analysis of the virome composition from 30 F. poae showed that the presence of Fusarium poae mitovirus 3 and other two viruses could increase the F. poae growth rate. The curing experiment and pathogenicity test in Petri indicated that Fusarium poae hypovirus 1 might be associated with the host hypovirulence phenotype, while Fusarium poae fusagravirus 1 and Fusarium poae partitivirus 3 may have some beneficial effect on host pathogenicity.
Resumo:
Background I filtri dializzatori ad alto flusso potrebbero mitigare la “tempesta citochinica" nell'infezione da Sars-COV-2, ma il loro impatto nei pazienti in dialisi cronica non è accertato. Lo scopo delle studio è valutare l’effetto del filtro in triacetato asimmetrico di cellulosa (ATA) e in polimetilmetacrilato (PMMA) sui marcatori infiammatori in pazienti in dialisi cronica affetti da SARS-CoV-2. Metodi Si tratta di uno studio prospettico osservazionale su pazienti in trattamento emodialitico cronicp con COVID-19 arruolati da marzo 2020 a Maggio 2021.Le variabili cliniche, la conta leucocitaria, la IL-6, la proteina C-reattiva (PCR), la procalcitonina (PCT) e la ferritina sono state determinate al basale. I valori ematici di PCR, PCT, e IL-6 sono stati determinati pre e post-dialisi per ogni seduta effettuata (i valori ottenuti sono stati corretti per ’emoconcentrazione). I pazienti sono stati trattati con emodiafiltrazione online con un filtro ad alto flusso in PMMA o ATA. L’end-point primario è stato valutare l’effetto dei due filtri sulle molecole infiammatorie, in particolare sulla reduction ratio (RR) della IL-6. Risultati Dei 74 pazienti arruolati, 48 sono trati trattati con filtro ATA e 26 con filtro PMMA (420 vs 191 sedute dialitiche). La RR percentuale mediana della IL-6 è risultata maggiore nel gruppo ATA (17,08% IQR -9,0 - 40.0 vs 2,95% IQR -34,63 – 27,32. Anche le RR percentuale di PCR e PCT sono state maggiori nel gruppo ATA. La regressione logistica multipla avente come variabile dipendente una IL-6RR maggiore del 25%, ha mostrato che ATA determinava una maggiore probabilità di raggiungere l’outcome dopo correzione per i parametri infiammatori pre-dialisi (OR 1,721 95% CI 1,176 – 2,538 p=0,0056). Al contrario una PCR elevata riduceva la probabilità di ottenere una IL-6RR significativa (OR 0,9101 95% CI 0,868 – 0,949, p<0.0001). Conclusioni Nella nostra popolazione il filtro ATA ha mostrato un migliore profilo antiinfiammatorio.