928 resultados para Uncertainty quantification
Non-normal modal logics, quantification, and deontic dilemmas. A study in multi-relational semantics
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This dissertation is devoted to the study of non-normal (modal) systems for deontic logics, both on the propositional level, and on the first order one. In particular we developed our study the Multi-relational setting that generalises standard Kripke Semantics. We present new completeness results concerning the semantic setting of several systems which are able to handle normative dilemmas and conflicts. Although primarily driven by issues related to the legal and moral field, these results are also relevant for the more theoretical field of Modal Logic itself, as we propose a syntactical, and semantic study of intermediate systems between the classical propositional calculus CPC and the minimal normal modal logic K.
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Environmental computer models are deterministic models devoted to predict several environmental phenomena such as air pollution or meteorological events. Numerical model output is given in terms of averages over grid cells, usually at high spatial and temporal resolution. However, these outputs are often biased with unknown calibration and not equipped with any information about the associated uncertainty. Conversely, data collected at monitoring stations is more accurate since they essentially provide the true levels. Due the leading role played by numerical models, it now important to compare model output with observations. Statistical methods developed to combine numerical model output and station data are usually referred to as data fusion. In this work, we first combine ozone monitoring data with ozone predictions from the Eta-CMAQ air quality model in order to forecast real-time current 8-hour average ozone level defined as the average of the previous four hours, current hour, and predictions for the next three hours. We propose a Bayesian downscaler model based on first differences with a flexible coefficient structure and an efficient computational strategy to fit model parameters. Model validation for the eastern United States shows consequential improvement of our fully inferential approach compared with the current real-time forecasting system. Furthermore, we consider the introduction of temperature data from a weather forecast model into the downscaler, showing improved real-time ozone predictions. Finally, we introduce a hierarchical model to obtain spatially varying uncertainty associated with numerical model output. We show how we can learn about such uncertainty through suitable stochastic data fusion modeling using some external validation data. We illustrate our Bayesian model by providing the uncertainty map associated with a temperature output over the northeastern United States.
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In this thesis we address a collection of Network Design problems which are strongly motivated by applications from Telecommunications, Logistics and Bioinformatics. In most cases we justify the need of taking into account uncertainty in some of the problem parameters, and different Robust optimization models are used to hedge against it. Mixed integer linear programming formulations along with sophisticated algorithmic frameworks are designed, implemented and rigorously assessed for the majority of the studied problems. The obtained results yield the following observations: (i) relevant real problems can be effectively represented as (discrete) optimization problems within the framework of network design; (ii) uncertainty can be appropriately incorporated into the decision process if a suitable robust optimization model is considered; (iii) optimal, or nearly optimal, solutions can be obtained for large instances if a tailored algorithm, that exploits the structure of the problem, is designed; (iv) a systematic and rigorous experimental analysis allows to understand both, the characteristics of the obtained (robust) solutions and the behavior of the proposed algorithm.
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Landslide hazard and risk are growing as a consequence of climate change and demographic pressure. Land‐use planning represents a powerful tool to manage this socio‐economic problem and build sustainable and landslide resilient communities. Landslide inventory maps are a cornerstone of land‐use planning and, consequently, their quality assessment represents a burning issue. This work aimed to define the quality parameters of a landslide inventory and assess its spatial and temporal accuracy with regard to its possible applications to land‐use planning. In this sense, I proceeded according to a two‐steps approach. An overall assessment of the accuracy of data geographic positioning was performed on four case study sites located in the Italian Northern Apennines. The quantification of the overall spatial and temporal accuracy, instead, focused on the Dorgola Valley (Province of Reggio Emilia). The assessment of spatial accuracy involved a comparison between remotely sensed and field survey data, as well as an innovative fuzzylike analysis of a multi‐temporal landslide inventory map. Conversely, long‐ and short‐term landslide temporal persistence was appraised over a period of 60 years with the aid of 18 remotely sensed image sets. These results were eventually compared with the current Territorial Plan for Provincial Coordination (PTCP) of the Province of Reggio Emilia. The outcome of this work suggested that geomorphologically detected and mapped landslides are a significant approximation of a more complex reality. In order to convey to the end‐users this intrinsic uncertainty, a new form of cartographic representation is needed. In this sense, a fuzzy raster landslide map may be an option. With regard to land‐use planning, landslide inventory maps, if appropriately updated, confirmed to be essential decision‐support tools. This research, however, proved that their spatial and temporal uncertainty discourages any direct use as zoning maps, especially when zoning itself is associated to statutory or advisory regulations.
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Magnetic Resonance Spectroscopy (MRS) is an advanced clinical and research application which guarantees a specific biochemical and metabolic characterization of tissues by the detection and quantification of key metabolites for diagnosis and disease staging. The "Associazione Italiana di Fisica Medica (AIFM)" has promoted the activity of the "Interconfronto di spettroscopia in RM" working group. The purpose of the study is to compare and analyze results obtained by perfoming MRS on scanners of different manufacturing in order to compile a robust protocol for spectroscopic examinations in clinical routines. This thesis takes part into this project by using the GE Signa HDxt 1.5 T at the Pavillion no. 11 of the S.Orsola-Malpighi hospital in Bologna. The spectral analyses have been performed with the jMRUI package, which includes a wide range of preprocessing and quantification algorithms for signal analysis in the time domain. After the quality assurance on the scanner with standard and innovative methods, both spectra with and without suppression of the water peak have been acquired on the GE test phantom. The comparison of the ratios of the metabolite amplitudes over Creatine computed by the workstation software, which works on the frequencies, and jMRUI shows good agreement, suggesting that quantifications in both domains may lead to consistent results. The characterization of an in-house phantom provided by the working group has achieved its goal of assessing the solution content and the metabolite concentrations with good accuracy. The goodness of the experimental procedure and data analysis has been demonstrated by the correct estimation of the T2 of water, the observed biexponential relaxation curve of Creatine and the correct TE value at which the modulation by J coupling causes the Lactate doublet to be inverted in the spectrum. The work of this thesis has demonstrated that it is possible to perform measurements and establish protocols for data analysis, based on the physical principles of NMR, which are able to provide robust values for the spectral parameters of clinical use.
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Eisbohrkerne stellen wertvolle Klimaarchive dar, da sie atmosphärisches Aerosol konservieren. Die Analyse chemischer Verbindungen als Bestandteil atmosphärischer Aerosole in Eisbohrkernen liefert wichtige Informationen über Umweltbedingungen und Klima der Vergangenheit. Zur Untersuchung der α-Dicarbonyle Glyoxal und Methylglyoxal in Eis- und Schneeproben wurde eine neue, sensitive Methode entwickelt, die die Stir Bar Sorptive Extraction (SBSE) mit der Hochleistungsflüssigchromatographie-Massenspektrometrie (HPLC-MS) kombiniert. Zur Analyse von Dicarbonsäuren in Eisbohrkernen wurde eine weitere Methode entwickelt, bei der die Festphasenextraktion mit starkem Anionenaustauscher zum Einsatz kommt. Die Methode erlaubt die Quantifizierung aliphatischer Dicarbonsäuren (≥ C6), einschließlich Pinsäure, sowie aromatischer Carbonsäuren (wie Phthalsäure und Vanillinsäure), wodurch die Bestimmung wichtiger Markerverbindungen für biogene und anthropogene Quellen ermöglicht wurde. Mit Hilfe der entwickelten Methoden wurde ein Eisbohrkern aus den Schweizer Alpen analysiert. Die ermittelten Konzentrationsverläufe der Analyten umfassen die Zeitspanne von 1942 bis 1993. Mittels einer Korrelations- und Hauptkomponentenanalyse konnte gezeigt werden, dass die organischen Verbindungen im Eis hauptsächlich durch Waldbrände und durch vom Menschen verursachte Schadstoffemissionen beeinflusst werden. Im Gegensatz dazu sind die Konzentrationsverläufe einiger Analyten auf den Mineralstaubtransport auf den Gletscher zurückzuführen. Zusätzlich wurde ein Screening der Eisbohrkernproben mittels ultrahochauflösender Massenspektrometrie durchgeführt. Zum ersten Mal wurden in diesem Rahmen auch Organosulfate und Nitrooxyorganosulfate in einem Eisbohrkern identifiziert.
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Troposphärisches Ozon ist bekannt als wichtiges Oxidationsmittel und als Vorläufergas hoch reaktiver Radikale. Es zählt zu den wichtigsten Treibhausgasen und wirkt bei hohen Konzentrationen an der Erdoberfläche giftig für alle Lebewesen. Zwar wird der Großteil des troposphärischen Ozons photochemisch produziert, ein erheblicher Anteil hat aber stratosphärischen Ursprung und wird entlang von Tropopausenfalten in Zyklonen in die Troposphäre transportiert. Dieser Transport von Luftmassen aus der Stratosphäre in diernTroposphäre (STT) kann zu einem kurzzeitigen, starken Ozonanstieg am Boden führen und langfristig die Chemie der Troposphäre beeinflussen. Die Quantifizierung des Ozoneintrages und die Identifizierung der dafür verantwortlichen Prozesse ist mit großen Unsicherheiten belastet und ein aktuelles Forschungsthema.rnAufgrund ihrer groben Auflösung ist es mit globalen Modellen nicht möglich, die Details dieser STT-Prozesse zu erfassen. Deshalb wird in dieser Arbeit das Modellsystem MECO(n) genutzt, welches das regionale Atmosphärenchemie- und Klimamodell COSMO/MESSy mit dem globalen Chemie-Klimamodell ECHAM5/MESSy (EMAC) koppelt. Eine einheitliche Prozessparametrisierung ermöglicht konsistente, simultane Simulationen in verschiedenen Modellauflösungen. Ein als Teil dieser Arbeit neu entwickeltes Submodell erlaubt die Initialisierung künstlicher, passiver Tracer in Abhängigkeit verschiedener Variablen. Mit einem auf diese Weise freigesetzten, stratosphärischen Tracer lässt sich Ozon mit stratosphärischer Herkunft von solchem, das photochemisch produziert wurde, unterscheiden.rnIm Rahmen einer Fallstudie werden die Austauschprozesse an einer Tropopausenfalte sowohl aus der Eulerischen, als auch aus der Lagrangeschen Perspektive betrachtet. Die Analyse der STT-Prozesse zeigt, dass Luftmassen aus der Stratosphäre durch turbulente und diabatische Prozesse am Rand der Tropopausenfalte in die Troposphäre gelangen und anschließend bis zum Boden transportiert werden. Diese absinkenden, stratosphärischen Luftmassen führen in den Simulationen zu Ozonanstiegen am Boden, die mit Beobachtungsdaten evaluiert werden können. Es wird gezeigt, dass die Ergebnisse der feiner auflösendenrnModellinstanz gut mit den Messungen übereinstimmen.rnIn einer Lagrangeschen Analyse lassen sich Mischungszeitskalen für STT-Prozesse bestimmen. Es wird gezeigt, dass Luftpakete, die sich länger als zehn Stunden in der Troposphäre aufhalten, diese durch den Eintrag ihrer stratosphärischen Tracereigenschaften beeinflussen und daher nicht vernachlässigbar sind. Eine weitere Studie gibt Aufschluss über die Effektivität der Mischung an Tropopausenfalten: Fast die gesamte Luftmasse, die sich zu einem bestimmten Zeitpunkt in der Tropopausenfalte befindet, gelangt innerhalb von zwei Tagen in die Troposphäre.
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One of the most serious problems of the modern medicine is the growing emergence of antibiotic resistance among pathogenic bacteria. In this circumstance, different and innovative approaches for treating infections caused by multidrug-resistant bacteria are imperatively required. Bacteriophage Therapy is one among the fascinating approaches to be taken into account. This consists of the use of bacteriophages, viruses that infect bacteria, in order to defeat specific bacterial pathogens. Phage therapy is not an innovative idea, indeed, it was widely used around the world in the 1930s and 1940s, in order to treat various infection diseases, and it is still used in Eastern Europe and the former Soviet Union. Nevertheless, Western scientists mostly lost interest in further use and study of phage therapy and abandoned it after the discovery and the spread of antibiotics. The advancement of scientific knowledge of the last years, together with the encouraging results from recent animal studies using phages to treat bacterial infections, and above all the urgent need for novel and effective antimicrobials, have given a prompt for additional rigorous researches in this field. In particular, in the laboratory of synthetic biology of the department of Life Sciences at the University of Warwick, a novel approach was adopted, starting from the original concept of phage therapy, in order to study a concrete alternative to antibiotics. The innovative idea of the project consists in the development of experimental methodologies, which allow to engineer a programmable synthetic phage system using a combination of directed evolution, automation and microfluidics. The main aim is to make “the therapeutics of tomorrow individualized, specific, and self-regulated” (Jaramillo, 2015). In this context, one of the most important key points is the Bacteriophage Quantification. Therefore, in this research work, a mathematical model describing complex dynamics occurring in biological systems involving continuous growth of bacteriophages, modulated by the performance of the host organisms, was implemented as algorithms into a working software using MATLAB. The developed program is able to predict different unknown concentrations of phages much faster than the classical overnight Plaque Assay. What is more, it gives a meaning and an explanation to the obtained data, making inference about the parameter set of the model, that are representative of the bacteriophage-host interaction.
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Il cancro della prostata (PCa) è il tumore maligno non-cutaneo più diffuso tra gli uomini ed è il secondo tumore che miete più vittime nei paesi occidentali. La necessità di nuove tecniche non invasive per la diagnosi precoce del PCa è aumentata negli anni. 1H-MRS (proton magnetic resonance spectroscopy) e 1H-MRSI (proton magnetic resonance spectroscopy imaging) sono tecniche avanzate di spettroscopia in risonanza magnetica che permettono di individuare presenza di metaboliti come citrato, colina, creatina e in alcuni casi poliammine in uno o più voxel nel tessuto prostatico. L’abbondanza o l’assenza di uno di questi metaboliti rende possibile discriminare un tessuto sano da uno patologico. Le tecniche di spettroscopia RM sono correntemente utilizzate nella pratica clinica per cervello e fegato, con l’utilizzo di software dedicati per l’analisi degli spettri. La quantificazione di metaboliti nella prostata invece può risultare difficile a causa del basso rapporto segnale/rumore (SNR) degli spettri e del forte accoppiamento-j del citrato. Lo scopo principale di questo lavoro è di proporre un software prototipo per la quantificazione automatica di citrato, colina e creatina nella prostata. Lo sviluppo del programma e dei suoi algoritmi è stato portato avanti all’interno dell’IRST (Istituto Romagnolo per lo Studio e la cura dei Tumori) con l’aiuto dell’unità di fisica sanitaria. Il cuore del programma è un algoritmo iterativo per il fit degli spettri che fa uso di simulazioni MRS sviluppate con il pacchetto di librerie GAMMA in C++. L’accuratezza delle quantificazioni è stata testata con dei fantocci realizzati all’interno dei laboratori dell’istituto. Tutte le misure spettroscopiche sono state eseguite con il nuovo scanner Philips Ingenia 3T, una delle machine di risonanza magnetica più avanzate per applicazioni cliniche. Infine, dopo aver eseguito i test in vitro sui fantocci, sono stati acquisiti gli spettri delle prostate di alcuni volontari sani, per testare se il programma fosse in grado di lavorare in condizioni di basso SNR.
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Pes cavovarus affects the ankle biomechanics and may lead to ankle arthrosis. Quantitative T2 STAR (T2*) magnetic resonance (MR) mapping allows high resolution of thin cartilage layers and quantitative grading of cartilage degeneration. Detection of ankle arthrosis using T2* mapping in cavovarus feet was evaluated. Eleven cavovarus patients with symptomatic ankle arthrosis (13 feet, mean age 55.6 years, group 1), 10 cavovarus patients with no or asymptomatic, mild ankle arthrosis (12 feet, mean age 41.8 years, group 2), and 11 controls without foot deformity (18 feet, mean age 29.8 years, group 3) had quantitative T2* MR mapping. Additional assessment included plain radiographs and the American Orthopaedic Foot and Ankle Society (AOFAS) score (groups 1 and 2 only). Mean global T2* relaxation time was significantly different between groups 1 and 2 (p = 0.001) and groups 1 and 3 (p = 0.017), but there was no significance for decreased global T2* values in group 2 compared to group 3 (p = 0.345). Compared to the medial compartment T2* values of the lateral compartment were significantly (p = 0.025) higher within group 1. T2* values in the medial ankle joint compartment of group 2 were significantly lower than those of group 1 (p = 0.019). Ankle arthrosis on plain radiographs and the AOFAS score correlated significantly with T2* values in the medial compartment of group 1 (p = 0.04 and 0.039, respectively). Biochemical, quantitative T2* MR mapping is likely effective to evaluate ankle arthrosis in cavovarus feet but further studies are required.
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To prospectively evaluate a 3-dimensional spoiled gradient-dual-echo (3D SPGR-DE) magnetic resonance imaging (MRI) sequence for the qualitative and quantitative analysis of liver fat content (LFC) in patients with the suspicion of fatty liver disease using histopathology as the standard of reference.
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This in situ study evaluated the discriminatory power and reliability of methods of dental plaque quantification and the relationship between visual indices (VI) and fluorescence camera (FC) to detect plaque.
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Therapy of metacarpal neck fractures depending on radiographically measured palmar angulation is discussed controversially in the literature. Some authors describe normal hand function of malunited metacarpal neck fractures with a palmar angulation up to 70°; others define 30° as the uppermost limit to maintain normal hand function. However, the methods of measuring palmar angulation are not clearly defined. Here, we present a new method to measure palmar angulation using ultrasound. The aim of this prospective study is to compare the radiographic methods of measuring palmar angulation with the ultrasound method. PATIENTS/MATERIAL AND METHOD: 20 patients with a neck fracture of the metacarpals IV or V were treated either conservatively or operatively. 2 weeks after trauma or operation, an x-ray was performed. 2 examiners measured the palmar angulation on the oblique and lateral projections using 2 different methods (medullary canal and dorsal cortex methods). At the same time, the 2 examiners performed measurements of palmar angulation using ultrasound. The measurements obtained with the different methods as well as by the 2 examiners at 2 different terms were compared. Intra- and interobserver reliability of each method was calculated, and for the ultrasound method a test for accuracy of the measured angles was performed.
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Accidents can lead to difficult boundary situations. Such situations often take place in the emergency units. The medical team thus often and inevitably faces professional uncertainty in their decision-making. It is essential to communicate these uncertainties within the medical team, instead of downplaying or overriding existential hurdles in decision-making. Acknowledging uncertainties might lead to alert and prudent decisions. Thus uncertainty can have ethical value in treatment or withdrawal of treatment. It does not need to be covered in evidence-based arguments, especially as some singular situations of individual tragedies cannot be grasped in terms of evidence-based medicine.