8 resultados para system dynamics analysis
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
During recent years a consistent number of central nervous system (CNS) drugs have been approved and introduced on the market for the treatment of many psychiatric and neurological disorders, including psychosis, depression, Parkinson disease and epilepsy. Despite the great advancements obtained in the treatment of CNS diseases/disorders, partial response to therapy or treatment failure are frequent, at least in part due to poor compliance, but also genetic variability in the metabolism of psychotropic agents or polypharmacy, which may lead to sub-therapeutic or toxic plasma levels of the drugs, and finally inefficacy of the treatment or adverse/toxic effects. With the aim of improving the treatment, reducing toxic/side effects and patient hospitalisation, Therapeutic Drug Monitoring (TDM) is certainly useful, allowing for a personalisation of the therapy. Reliable analytical methods are required to determine the plasma levels of psychotropic drugs, which are often present at low concentrations (tens or hundreds of nanograms per millilitre). The present PhD Thesis has focused on the development of analytical methods for the determination of CNS drugs in biological fluids, including antidepressants (sertraline and duloxetine), antipsychotics (aripiprazole), antiepileptics (vigabatrin and topiramate) and antiparkinsons (pramipexole). Innovative methods based on liquid chromatography or capillary electrophoresis coupled to diode-array or laser-induced fluorescence detectors have been developed, together with the suitable sample pre-treatment for interference removal and fluorescent labelling in case of LIF detection. All methods have been validated according to official guidelines and applied to the analysis of real samples obtained from patients, resulting suitable for the TDM of psychotropic drugs.
Resumo:
Cardiotocography (CTG) is a widespread foetal diagnostic methods. However, it lacks of objectivity and reproducibility since its dependence on observer's expertise. To overcome these limitations, more objective methods for CTG interpretation have been proposed. In particular, many developed techniques aim to assess the foetal heart rate variability (FHRV). Among them, some methodologies from nonlinear systems theory have been applied to the study of FHRV. All the techniques have proved to be helpful in specific cases. Nevertheless, none of them is more reliable than the others. Therefore, an in-depth study is necessary. The aim of this work is to deepen the FHRV analysis through the Symbolic Dynamics Analysis (SDA), a nonlinear technique already successfully employed for HRV analysis. Thanks to its simplicity of interpretation, it could be a useful tool for clinicians. We performed a literature study involving about 200 references on HRV and FHRV analysis; approximately 100 works were focused on non-linear techniques. Then, in order to compare linear and non-linear methods, we carried out a multiparametric study. 580 antepartum recordings of healthy fetuses were examined. Signals were processed using an updated software for CTG analysis and a new developed software for generating simulated CTG traces. Finally, statistical tests and regression analyses were carried out for estimating relationships among extracted indexes and other clinical information. Results confirm that none of the employed techniques is more reliable than the others. Moreover, in agreement with the literature, each analysis should take into account two relevant parameters, the foetal status and the week of gestation. Regarding the SDA, results show its promising capabilities in FHRV analysis. It allows recognizing foetal status, gestation week and global variability of FHR signals, even better than other methods. Nevertheless, further studies, which should involve even pathological cases, are necessary to establish its reliability.
Resumo:
In this thesis we focus on optimization and simulation techniques applied to solve strategic, tactical and operational problems rising in the healthcare sector. At first we present three applications to Emilia-Romagna Public Health System (SSR) developed in collaboration with Agenzia Sanitaria e Sociale dell'Emilia-Romagna (ASSR), a regional center for innovation and improvement in health. Agenzia launched a strategic campaign aimed at introducing Operations Research techniques as decision making tools to support technological and organizational innovations. The three applications focus on forecast and fund allocation of medical specialty positions, breast screening program extension and operating theater planning. The case studies exploit the potential of combinatorial optimization, discrete event simulation and system dynamics techniques to solve resource constrained problem arising within Emilia-Romagna territory. We then present an application in collaboration with Dipartimento di Epidemiologia del Lazio that focuses on population demand of service allocation to regional emergency departments. Finally, a simulation-optimization approach, developed in collaboration with INESC TECH center of Porto, to evaluate matching policies for the kidney exchange problem is discussed.
Resumo:
Several decision and control tasks involve networks of cyber-physical systems that need to be coordinated and controlled according to a fully-distributed paradigm involving only local communications without any central unit. This thesis focuses on distributed optimization and games over networks from a system theoretical perspective. In the addressed frameworks, we consider agents communicating only with neighbors and running distributed algorithms with optimization-oriented goals. The distinctive feature of this thesis is to interpret these algorithms as dynamical systems and, thus, to resort to powerful system theoretical tools for both their analysis and design. We first address the so-called consensus optimization setup. In this context, we provide an original system theoretical analysis of the well-known Gradient Tracking algorithm in the general case of nonconvex objective functions. Then, inspired by this method, we provide and study a series of extensions to improve the performance and to deal with more challenging settings like, e.g., the derivative-free framework or the online one. Subsequently, we tackle the recently emerged framework named distributed aggregative optimization. For this setup, we develop and analyze novel schemes to handle (i) online instances of the problem, (ii) ``personalized'' optimization frameworks, and (iii) feedback optimization settings. Finally, we adopt a system theoretical approach to address aggregative games over networks both in the presence or absence of linear coupling constraints among the decision variables of the players. In this context, we design and inspect novel fully-distributed algorithms, based on tracking mechanisms, that outperform state-of-the-art methods in finding the Nash equilibrium of the game.
Resumo:
La ricerca oggetto della tesi riguarda la disamina delle esperienze comunitarie e nazionali in Europa in materia di elusione IVA ed antielusione IVA, al fine di esaminare le utilizzabili esperienze in materia per la Cina che dovrebbe iniziare a prendere le giuste azioni per fronteggiare il problema della crescente diffusione dei fenomeni dell’elusione IVA, in particolare nel contesto della riforma perdurante dell’IVA cinese verso il modello moderno. A questo fine, prima la tesi ha analizzato dettagliatamente le seguenti principali questioni sulla base delle esperienze comunitarie e nazionali dei determinati Stati Membri dell’UE: la definizione dell’elusione fiscale generale (a tale proposito, più rilevanti le differenze tra elusione fiscale ed altri relativi concetti come risparmio d’imposta, evasione fiscale e simulazione e la relazione intrinseca tra elusione fiscale ed altri relativi concetti come frode alla legge ed abuso del diritto), la definizione dell’elusione IVA (a tale proposito, più rilevanti gli aspetti di particolare interesse ai fini della definizione dell’elusione IVA), i principi e metodologie dell’elusione IVA, le applicazioni delle varie misure antielusive rivolte all’elusione IVA nell’ordinamento comunitario e negli ordinamenti interni degli alcuni principali Stati Membri dell’UE (a tale proposito, più rilevanti l’applicazone del principio Halifax, quale norma antielusiva generale basata sul principio di divieto dell’abuso del diritto, e la considerazione delle altre soluzioni antielusive applicabili nell’IVA, comprese correzioni normative e clausole antielusive specifiche), gli effetti dell’antielusione IVA e i limiti entro cui l’autorità impositiva può esercitare l’antielusione IVA per la tutela degli interessi legittimi dei soggetti passivi come certezza giuridica ed autonomia contrattuale. Poi, la tesi ha avanzato le proposte relative al perfezionamento delle soluzioni antielusive IVA nell’ordinamento tributario cinese, dopo presentati i principali regimi attuali dell’IVA cinese e analizzate le situazioni attuali realtive all’elusione IVA e all’antielusione IVA nel sistema fiscale cinese.
Resumo:
In this thesis three measurements of top-antitop differential cross section at an energy in the center of mass of 7 TeV will be shown, as a function of the transverse momentum, the mass and the rapidity of the top-antitop system. The analysis has been carried over a data sample of about 5/fb recorded with the ATLAS detector. The events have been selected with a cut based approach in the "one lepton plus jets" channel, where the lepton can be either an electron or a muon. The most relevant backgrounds (multi-jet QCD and W+jets) have been extracted using data driven methods; the others (Z+ jets, diboson and single top) have been simulated with Monte Carlo techniques. The final, background-subtracted, distributions have been corrected, using unfolding methods, for the detector and selection effects. At the end, the results have been compared with the theoretical predictions. The measurements are dominated by the systematic uncertainties and show no relevant deviation from the Standard Model predictions.
Resumo:
La rottura del Legamento Crociato Craniale (LCCr) rappresenta una delle patologie ortopediche di maggiore riscontro clinico nella specie canina. In seguito a rottura del LCCr si presenta un continuo slittamento craniale della tibia il quale esita in un processo osteoartrosico. La risoluzione chirurgica rappresenta la migliore soluzione terapeutica. Le tecniche chirurgiche extra-articolari con sfruttamento dei punti isometrici del ginocchio si presentano come delle procedure molto diffuse e utilizzate. Questa tesi propone di validare l’uso di un nuovo sistema di navigazione computerizzato-assistito per la valutazione cinematica durante la ricostruzione del LCCr nel cane, ma soprattutto di studiare e confrontare il comportamento e l’efficacia dopo ricostruzione TightRope (TR) in due diverse coppie di punti isometrici. Abbiamo effettuato due analisi in parallelo. La prima eseguendo interventi chirurgici con tecnica TR su 18 casi clinici e sfruttando il punto isometrico del femore (F2) e due diversi punti isometrici della tibia (T2 o T3). L’analisi prevedeva dei controlli postoperatori a 1, 3 e 6 mesi. Ad ogni controllo veniva effettuata una visita ortopedica, esami radiografici, un questionario di valutazione clinico e di soddisfazione del proprietario. Mentre nella ricerca Ex-Vivo abbiamo eseguito dei test su 14 preparati anatomici con l’utilizzo di un sistema di navigazione computerizzato per la rilevazione dei dati. L’analisi prevedeva la valutazione dell’articolazione in diversi stadi: LCCr intatto; LCCr rotto; dopo ricostruzione con TR in F2-T2 e tensionato a 22N, 44N e 99N; dopo ricostruzione con TR in F2-T3 e tensionato a 22N, 44N e 99N. Ad ogni stadio si eseguivano cinque test di valutazione, tra cui: Test del Cassetto, Test di compressione tibiale (TCT), Rotazione Interna/Esterna, Flesso/Estensione e Varo/Valgo. Lo scopo di tale studio è quello di confrontare tra loro i punti isometrici del ginocchio e di analizzare l’efficacia della tecnica TR nelle due differenti condizioni di isometria (F2-T2 e F2-T3).
Resumo:
This work is focused on the study of saltwater intrusion in coastal aquifers, and in particular on the realization of conceptual schemes to evaluate the risk associated with it. Saltwater intrusion depends on different natural and anthropic factors, both presenting a strong aleatory behaviour, that should be considered for an optimal management of the territory and water resources. Given the uncertainty of problem parameters, the risk associated with salinization needs to be cast in a probabilistic framework. On the basis of a widely adopted sharp interface formulation, key hydrogeological problem parameters are modeled as random variables, and global sensitivity analysis is used to determine their influence on the position of saltwater interface. The analyses presented in this work rely on an efficient model reduction technique, based on Polynomial Chaos Expansion, able to combine the best description of the model without great computational burden. When the assumptions of classical analytical models are not respected, and this occurs several times in the applications to real cases of study, as in the area analyzed in the present work, one can adopt data-driven techniques, based on the analysis of the data characterizing the system under study. It follows that a model can be defined on the basis of connections between the system state variables, with only a limited number of assumptions about the "physical" behaviour of the system.