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Meandering rivers morphodynamics - integrating nonlinear modeling and remote sensing
Get PDFDuring the past decades, the systematic investigation of the morphodynamics of meandering rivers mostly involved the theoretical-analytical methodology. The development of analytical models enabled the definition of equilibrium conditions, stability and evolution of river meanders and to investigate the interaction between planform and bedform processes and mechanisms. In recent years the new branch of remote sensing applied to river morphodynamics has been constantly developing simultaneously to the rapid increase of computational and satellite resources. The remote sensing analysis is nowadays employed in a wide range fields in geophysics; for this reason, the past years have seen the prolific development of numerous algorithms for remote sensing analysis. However, remote sensing of meandering river morphodynamics has not been consistently integrated with morphodynamic modelling so far. There is a lack of sophisticated algorithms for the extraction of extensive morphodynamic information from the available remotely sensed data; this gap prevented researchers from seeking systematic validation of analytical models to define their range of applicability, and to exploit their potential for improved insight on observations in real world meandering rivers. The evolutionary dynamics of the channel width, at local and bend scale, as well as the dynamics of bars in meandering rivers represent two major unsettled issues in our present understanding of river meandering dynamics.
In this thesis I first provide a systematic methodology for the automated extraction of meandering river morphodynamic information from multitemporal, multispectral remotely sensed data, coded in the PyRIS software. Moreover, I develop an analytical model to investigate the long-term planform evolution of periodic sequences of meander bends incorporating spatio-temporal variations of channel curvature, width and slope. A first model component predicts the temporal evolution of the channel width and slope based on a novel treatment of the sediment continuity at the reach scale. A second model component is a fully analytical, evolutionary model of periodic meanders with spatially and temporally oscillating width accounting for nonlinear feedbacks in flow and sediment transport by means of a two-parameters perturbation approach.
Application of the PyRIS software to several long reaches of free-flowing meandering rivers allows me to develop a consistent set of observations on the temporal and spatial evolution of channel width and curvature with unprecedented level of detail. Furthermore, model outcomes indicate that meander-averaged width and slope invariably decrease during meander development, and that the temporal adjustment of the hydraulic geometry is controlled by the ratio between the evolutionary timescales of planform and riverbed, quantified from the analyzed meandering rivers dataset. The nonlinear perturbation model indicates that width and curvature co-evolve according to a hysteretic behavior in time and predicts that the meander belt width dramatically decreases when the meander resonance threshold is crossed. The modelling approach predicts wider-at-bend meanders when the bank pull is dominant with respect to bar push, which in turn promotes meander bends that are wider at inflections.
Analytical modeling and remote sensing analysis are mostly integrated through a statistical approach; bend-scale evolutionary analysis of planform descriptors such as channel width, width oscillations and curvature in large pristine meandering rivers exhibit good agreement with the outcomes of the proposed analytical models.
Finally, the integration between analytical modeling and remote sensing analysis allows me to identify the key processes controlling the interaction between migrating sediment bars and planform-driven steady point bars. The conditions for the formation of migrating bars in meandering rivers are mostly related to the production of sediment supply by the basin, contrarily to the widespread idea that meandering rivers exhibiting migrating bars typically display lower values of the channel curvature
Studies on the synergistic protective activity of cancer antigens associated to engineered bacterial Outer Membrane Vesicles
Get PDFIntroduction
Bacterial Outer Membrane Vesicles (OMVs) are naturally produced by all Gram-negative bacteria and are emerging as an attractive vaccine platform. The exploitation of OMVs in cancer immunotherapy was tested by decorating them with cancer epitopes and by following their capacity to elicit protective immune responses, alone or in combination, using cancer mouse models. Furthermore, we tested whether cancer cell-derived exosomes (TEXs) and OMVs can form complexes and whether such complexes, which carry TEX- associated tumor antigens and OMV-associated immune-stimulatory molecules, elicit anti-tumor immune responses in vivo. Results
Immunization with OMVs engineered with two B cell epitopes (EGFRvIII and D8-mFAT1) induced tumor growth inhibition after mouse challenge with cell lines expressing the corresponding epitopes. Furthermore, mice immunized with engineered OMVs carrying two cancer epitopes, the EGFRvIII B cell epitope and the M30 CD4+ T cell epitope, were completely protected from EGFRvIIIB16F10 cell line expressing both epitopes, indicating the importance of multi-antigen immunization in cancer immunotherapy. Furthermore TEXs- OMVs immunization induced antibody responses against exosome antigens with a Th1-type profile. Finally, the combination of CT26-derived TEXs and MBP-D8-mFAT1 OMVs elicited synergistic protective activity against mouse challenge with CT26 cell line.
Conclusions
OMVs decorated with tumor antigens elicit antigen-specific, protective anti- tumor responses in mice. The synergistic protective activity of multiple epitopes simultaneously administered with OMVs, either by direct OMV engineering or by TEX-OMV combination, demonstrates the attractiveness of the OMV platform in cancer immunotherapy
Analysis methods for gravitational wave from binary neutron star coalescences: investigation on the post-merger phase
Get PDFThe coalescence of binary neutron stars (BNS) is amongst the most promising sources for advanced gravitational wave (GW) detectors. The forthcoming addition of the advanced Virgo interferometer to the LIGO detector network will greatly improve the estimation of GW characteristics and therefore the capabilities to test features in the GW signal emitted by the coalescence of a NS binary. Such an observation can constrain the equation
of state of these stars in at least two ways: by investigating smaller effects on top of the signal from the inspiral phase due to the tidal deformability of the components and by characterizing the emission from the possible highly excited NS remnant after the merger. Both methods promise to probe matter up to yet unknown and unexplored supranuclear densities, provided that the signal-to-noise ratio (SNR) at which the single GW is detected is sufficiently high or that the results from more detections can be combined together. Depending on mass and Equation of State (EoS) of the NS progenitors,
the final fate of the merger can produce either a prompt collapse to black hole (BH) or a massive NS remnant. In the latter case, the merger remnant could be a short-lived, hypermassive NS (HMNS) collapsing to a BH within a few tens of ms after merger, or a long-lived NS, which in turn can be either supramassive (SMNS), i.e. collapsing to a BH on much longer timescales of order of seconds, or even a stable NS. These remnants will be highly excited, showing transient nonaxisymmetric deformations and quadrupolar oscillations, which are expected to emit GWs peaked in the frequency range around 2-3 kHz. The observation of these Post Merger (PM) fingerprints, would allow to constrain the EoS and at the same time to estimate combinations of stellar parameters, such as
mass and radius of the two objects.
With these motivations, my PhD thesis addressed the development of a new data analysis tool in order to investigate the GW signal emitted during the PM phase following a NS coalescence. The analysis procedure is developed inside the framework of the Coherent Wave Burst (cWB) pipeline which is employed by LIGO and Virgo collaboration to search for burst signals, i.e. it makes minimal assumption on the GW morphology and provides a robust coverage of generic GW transients
Effect of Tissue Viscoelasticity and Stiffness on Hemodynamics and Endothelial Cell Signaling
Get PDFCardiovascular disease (CVD) is the most common cause of death in the United States of America, accounting for 24% of all deaths each year,(Anderson et al., 2003) and is projected to rise above 20% globally by 2030.(Mathers and Loncar, 2006) Options for CVD treatment do exist, but are limited by availability of healthy replant tissue from the patient or long term effectiveness and failure rates of both autologous tissue grafts and artificial implants. Grafting failure may often be attributed to the poor
mimicry of the site-specific, healthy arterial tissue. While much TEVG research focuses on endothelialization of the graft lumen through chemical signaling,
mechanotransduction plays a large role in forming and maintaining a healthy endothelial cell (EC) monolayer. Arteries and grafts interact with hemodynamics to determine flow pulsatility and create healthy, or pathological, mechanical signaling environments. Though arterial tissue is known to be viscoelastic,(Armentano et al., 2006; Bergel, 1961; Bia et al., 2006) the importance of this in developing healthy blood flow is undetermined. Therefore, a gap in the knowledge occurs in the importance of arterial mechanics affecting graft outcomes. To address this we attempt to examine specific shortcomings: 1) Determine whether pathological flow is capable of maintaining EC monolayer in a low arterial compliance model, 2) Establish methods of catering protein hydrogel frequency-dependent properties towards establishing biodegradable materials intended for
TEVG, 3) Determine benefits of viscous wall damping in improving hemodynamics towards improved cell response.
This proposal centers on improving cell response to pathological hemodynamics through catered viscoelastic material response at the arterial wall. To address this, we hypothesize that maintaining healthy EC monolayer is predicated on hemodynamic mechanotransduction, which results from both graft compliance and viscous damping of the material. To validate this hypothesis, we examine healthy and pathological hemodynamic effects on EC monoculture, and systematically determine the role of viscoelastic material response in maintaining healthy hemodynamics
"Spes optima regni". L'azione politica di Lotario I (795-855) alla luce delle fonti storico-narrative del secolo IX
Get PDFLa presente tesi indaga il ruolo svolto da Lotario I (795-855), figlio dell’imperatore Ludovico il Pio e associato al potere imperiale dall’817, all’interno della storia dell’Impero carolingio, specificatamente tra gli anni 814 e 843. L’azione di governo di Lotario è stata esaminata principalmente sulla base di un’attenta analisi delle fonti storico-narrative coeve alla vita dell’imperatore, indagine che ha permesso di rivedere e considerare sotto un’ottica nuova alcuni eventi chiave della storia carolingia, tra cui in primis il rapporto di Lotario con il padre Ludovico il Pio e il fratellastro Carlo il Calvo
Decentralization, Democracy and Development : Examining the potential and limits of subnational empowerment
No full textAs the discourse on economic development has expanded its focus to a broader set of interrelated economic, social, and political variables, an important conclusion has been that sustainable and inclusive development requires not only economic and social policies, but also political empowerment to foster a deliberative and participatory development process. The state versus market led development debate has been increasingly conducive to the role of state since 1990s mainly due to the developmental state experiences in East Asia in particular, and the high social costs of pursuing market oriented reforms or Structural Adjustment Programs in many developing countries. The growth spurts and the successive downturns delivered little on account of sustainable and inclusive growth.
The nature of an ideal state, in contemporary times, can be argued to be developmental and democratic; characterized by redistributive growth, broad-based participation, pro-poor policies, and responsiveness of public policy to local needs. Given the intricacies of the contemporary world where Keynesian and neo-liberal values contest for space simultaneously, the (re)configuration of the role of the state while fostering democratization is an important dimension to consider. In this context, it is increasingly argued that subnational democracy is important in revitalizing and reinvigorating democratic systems, as well as promoting better public governance. This thesis attempts to examine the concepts of Decentralization and the Democratic Developmental State, the political incentives that determine the substantiveness of decentralization reforms, and whether subnational empowerment through decentralization is conducive to democratic developmentalism
La Corte d'Assise Straordinaria di Udine e i processi per collaborazionismo in Friuli 1945-1947
No full textQuesta ricerca si propone di studiare la Corte d’Assise Straordinaria (CAS) di Udine e i processi da essa celebrati utilizzando per la prima volta l’intero materiale documentario prodotto dalla Corte al fine di indagarne da un lato la struttura e il funzionamento e, dall’altro, studiare l’anatomia del collaborazionismo esaminandone le peculiarità, l’entità e l’evoluzione nel particolare contesto friulano
Fare gli Italiani dell'Egeo: Il Dodecaneso dall'Impero ottomano all'Impero del fascismo
No full textScopo della tesi è indagare i modi e le forme attraverso cui la percezione dell'opinione popolare egea da parte delle autorità italiane hanno influenzato trasformazioni della vita giuridica, economica e sociale del Dodecaneso nel periodo compreso tra la spartizione dell'Impero ottomano e la proclamazione dell'Impero fascista. Attraverso questa chiave interpretativa si tenterà di enucleare alcune peculiarità del Possedimento delle Isole Italiane dell'Egeo rispetto al contesto italiano e a quello internazionale. Per ricostruire gli sviluppi e gli esiti di tale rapporto si è proceduto a una disamina analitica, mettendo a fuoco le vicende che videro coinvolti gli attori locali e gli organi di governo metropolitani, le problematiche affrontate e le decisioni prese sulla base di documenti interni (studi, memorie, carteggi) e di fonti ufficiali (pubblicistica italiana e internazionale, atti di convegno, bilanci, discorsi parlamentari, leggi e regolamenti). Si è poi cercato di interpretare i singoli eventi, evidenziando le specificità del contesto egeo rispetto agli altri territori sottoposti alla sovranità italiana, le linee di continuità o le divergenze tra le pratiche di governo italiane e quelle ottomane, le finalità attribuite alla politica locale, gli effetti della Grande depressione e dello scenario politico successivo alla Crisi di Abissinia sul tessuto sociale e sulle pratiche amministrative. Il lavoro è diviso in quattro capitoli. Il primo è un'introduzione storica che descrive l'organizzazione politica e sociale dell'Arcipelago durante gli ultimi decenni della dominazione ottomana, le vicende che spinsero gli Italiani all'occupazione del Dodecaneso, gli esiti della Guerra di Libia e delle Guerre balcaniche nell'opinione popolare egea e all'interno dei centri decisionali metropolitani. Nei due capitoli centrali si è deciso di seguire una struttura argomentativa tripartita. Vengono esposti dapprima gli scenari internazionali, con una particolare attenzione alle trattative diplomatiche che interessano la sorte dell'Arcipelago. In secondo luogo, vengono analizzate le politiche amministrative che furono pianificate e portate avanti con il perdurare della presenza italiana, tentando di mettere in luce non solo come le direttive inviate da Roma abbiano condizionato l'azione di governo degli amministratori, ma anche e soprattutto i modi e le forme in cui il preesistente quadro politico ed amministrativo ottomano, pur rimanendo formalmente in vigore, sia stato progressivamente modificato, vuoi per rispondere alle esigenze dei nuovi governanti, vuoi sulla base di spinte che provenivano dalla società civile egea. Infine si tenterà di mettere in luce come i mutamenti degli scenari internazionali e i diversi atteggiamenti adottati dall'amministrazione italiana abbiano influito sulla società dodecanesina, creando non solo oppressione e resistenza, ma anche nuove opportunità di crescita e di guadagno per le diverse classi e gruppi etnici, che adattarono le proprie condizioni di vita secondo dinamiche specifiche e furono in grado di negoziare la loro integrazione all'interno dei nuovi circuiti economici, politici e sociali prodotti dall'imperialismo italiano. L'ultimo capitolo mira invece ad evidenziare gli effetti del clima bellicistico e dell'atteggiamento più marcatamente espansionista esplicitato dal fascismo dopo la conquista dell'Etiopia nel Dodecaneso. Ciò ponendo l'accento sia sugli effetti che il nuovo clima politico, e più in particolare la rivalutazione strategica del Possedimento, ebbe sul rapporto tra Governo ed opinione popolare sia sulle valutazioni, di stampo razzista, che portarono Roma a considerare il Dodecaneso una sorta di laboratorio, o prototipo, per la futura espansione nei Balcani
Theory of Decision Based on Structural Health Monitoring
Get PDFThe average age of strategic constructions in the Western world is becoming higher and higher. Many of these structures need inspection, maintenance or replacement, resulting in significant costs. The accurate estimate of structural condition can make operators optimize the allocation of resources. Nowadays, the progress of technology and machine learning has made structural health monitoring appealing to the agencies that manage important structures. This has encouraged the research community in the study of new structural health monitoring methods. In spite of this, the use of monitoring data is often disregarded by practitioners, who still prefer to gather more information and then act based on experience. Similarly, unlike the design of civil structures, the design of structural health monitoring systems is carried out based on heuristics rather than on rigorous evaluations of the expected monitoring system effectiveness. In this doctoral thesis, I apply expected utility theory for the development of decision support systems to be used in structural health monitoring and I develop a procedure for the design of structural health monitoring systems that follows the scheme of semi-probabilistic structural design. The use of monitoring data in a decision support system that implements expected utility theory financially optimizes the management of civil structures. The proposed monitoring system design method enables practitioners to design monitoring systems using their experience and guarantees that the installation of a monitoring solution is financially convenient. I present the mathematical formulation for monitoring-based decision support systems and monitoring system design. Then, I propose the numerical algorithms for the development of monitoring-based decision support systems and solutions for monitoring data analysis. Finally, the proposed methods are applied to three case studies, which enabled me to discuss the application in real life and the hypotheses. The applications show also the feasibility of the proposed approaches and test the numerical algorithms
Spatial organization of ecologically-relevant high order flow properties and implications for river habitat assessment
Get PDFThe turbulent properties of flow in rivers are of fundamental importance to aquatic organisms yet are rarely quantified during routine river habitat assessment surveys or the design of restoration schemes due to their complex nature. This thesis uses a detailed review of the literature to highlight the various ways in which plants and animals modify the flow field, how this can deliver beneficial effects; and how turbulence can also generate threats to growth and survival. The thesis then presents the results from detailed field assessments of turbulence properties undertaken on low, intermediate and high gradient rivers to advance scientific understanding of the hydrodynamics of rivers and inform effective habitat assessment and restoration. A reach-scale comparison across sites reveals spatial variations in the relationships between turbulent parameters, emphasising the need for direct measurement of turbulence properties, while a geomorphic unit scale assessment suggests that variations in turbulence at the scale of individual roughness elements, and/or within the same broad groupings of geomorphic units (e.g. different types of pools) can have an important influence on hydraulic habitat. The importance of small-scale flow obstructions is further emphasised through analysis of the temporal dynamics of turbulence properties with changes in flow stage and vegetation growth. The highest magnitude temporal changes in turbulence properties were associated with individual boulders and vegetation patches respectively, indicating flow intensification around these sub-geomorphic unit scale features. Experimental research combining flow measurement with underwater videography reveals that more sophisticated turbulence parameters provide a better explanation of fish behaviour and habitat use under field conditions, further supporting direct measurement of turbulent properties where possible. The new insights into interactions between geomorphology, hydraulics and aquatic organisms generated by this work offer opportunities for refining habitat assessment and restoration design protocols to better integrate the important role of turbulence in generating suitable physical habitat for aquatic organisms