Dynamic services in mobile ad hoc networks

The increasing diffusion of wireless-enabled portable devices is pushing toward the design of novel service scenarios, promoting temporary and opportunistic interactions in infrastructure-less environments. Mobile Ad Hoc Networks (MANET) are the general model of these higly dynamic networks that can be specialized, depending on application cases, in more specific and refined models such as Vehicular Ad Hoc Networks and Wireless Sensor Networks. Two interesting deployment cases are of increasing relevance: resource diffusion among users equipped with portable devices, such as laptops, smart phones or PDAs in crowded areas (termed dense MANET) and dissemination/indexing of monitoring information collected in Vehicular Sensor Networks. The extreme dynamicity of these scenarios calls for novel distributed protocols and services facilitating application development. To this aim we have designed middleware solutions supporting these challenging tasks. REDMAN manages, retrieves, and disseminates replicas of software resources in dense MANET; it implements novel lightweight protocols to maintain a desired replication degree despite participants mobility, and efficiently perform resource retrieval. REDMAN exploits the high-density assumption to achieve scalability and limited network overhead. Sensed data gathering and distributed indexing in Vehicular Networks raise similar issues: we propose a specific middleware support, called MobEyes, exploiting node mobility to opportunistically diffuse data summaries among neighbor vehicles. MobEyes creates a low-cost opportunistic distributed index to query the distributed storage and to determine the location of needed information. Extensive validation and testing of REDMAN and MobEyes prove the effectiveness of our original solutions in limiting communication overhead while maintaining the required accuracy of replication degree and indexing completeness, and demonstrates the feasibility of the middleware approach.

A spectroscopic and photometric study of stellar populations in a sample of clusters in the Magellanic Clouds

This Ph.D. Thesis has been carried out in the framework of a long-term and large project devoted to describe the main photometric, chemical, evolutionary and integrated properties of a representative sample of Large and Small Magellanic Cloud (LMC and SMC respectively) clusters. The globular clusters system of these two Irregular galaxies provides a rich resource for investigating stellar and chemical evolution and to obtain a detailed view of the star formation history and chemical enrichment of the Clouds. The results discussed here are based on the analysis of high-resolution photometric and spectroscopic datasets obtained by using the last generation of imagers and spectrographs. The principal aims of this project are summarized as follows: • The study of the AGB and RGB sequences in a sample of MC clusters, through the analysis of a wide near-infrared photometric database, including 33 Magellanic globulars obtained in three observing runs with the near-infrared camera SOFI@NTT (ESO, La Silla). • The study of the chemical properties of a sample of MCs clusters, by using optical and near-infrared high-resolution spectra. 3 observing runs have been secured to our group to observe 9 LMC clusters (with ages between 100 Myr and 13 Gyr) with the optical high-resolution spectrograph FLAMES@VLT (ESO, Paranal) and 4 very young (<30 Myr) clusters (3 in the LMC and 1 in the SMC) with the near-infrared high-resolution spectrograph CRIRES@VLT. • The study of the photometric properties of the main evolutive sequences in optical Color- Magnitude Diagrams (CMD) obtained by using HST archive data, with the final aim of dating several clusters via the comparison between the observed CMDs and theoretical isochrones. The determination of the age of a stellar population requires an accurate measure of the Main Sequence (MS) Turn-Off (TO) luminosity and the knowledge of the distance modulus, reddening and overall metallicity. For this purpose, we limited the study of the age just to the clusters already observed with high-resolution spectroscopy, in order to date only clusters with accurate estimates of the overall metallicity.

Study of the thermal effects induced by magnetic resonance on endocardial leads: numerical models and experimental validation

Magnetic resonance imaging (MRI) is today precluded to patients bearing active implantable medical devices AIMDs). The great advantages related to this diagnostic modality, together with the increasing number of people benefiting from implantable devices, in particular pacemakers(PM)and carioverter/defibrillators (ICD), is prompting the scientific community the study the possibility to extend MRI also to implanted patients. The MRI induced specific absorption rate (SAR) and the consequent heating of biological tissues is one of the major concerns that makes patients bearing metallic structures contraindicated for MRI scans. To date, both in-vivo and in-vitro studies have demonstrated the potentially dangerous temperature increase caused by the radiofrequency (RF) field generated during MRI procedures in the tissues surrounding thin metallic implants. On the other side, the technical evolution of MRI scanners and of AIMDs together with published data on the lack of adverse events have reopened the interest in this field and suggest that, under given conditions, MRI can be safely performed also in implanted patients. With a better understanding of the hazards of performing MRI scans on implanted patients as well as the development of MRI safe devices, we may soon enter an era where the ability of this imaging modality may be more widely used to assist in the appropriate diagnosis of patients with devices. In this study both experimental measures and numerical analysis were performed. Aim of the study is to systematically investigate the effects of the MRI RF filed on implantable devices and to identify the elements that play a major role in the induced heating. Furthermore, we aimed at developing a realistic numerical model able to simulate the interactions between an RF coil for MRI and biological tissues implanted with a PM, and to predict the induced SAR as a function of the particular path of the PM lead. The methods developed and validated during the PhD program led to the design of an experimental framework for the accurate measure of PM lead heating induced by MRI systems. In addition, numerical models based on Finite-Differences Time-Domain (FDTD) simulations were validated to obtain a general tool for investigating the large number of parameters and factors involved in this complex phenomenon. The results obtained demonstrated that the MRI induced heating on metallic implants is a real risk that represents a contraindication in extending MRI scans also to patient bearing a PM, an ICD, or other thin metallic objects. On the other side, both experimental data and numerical results show that, under particular conditions, MRI procedures might be consider reasonably safe also for an implanted patient. The complexity and the large number of variables involved, make difficult to define a unique set of such conditions: when the benefits of a MRI investigation cannot be obtained using other imaging techniques, the possibility to perform the scan should not be immediately excluded, but some considerations are always needed.

Gonzalo Hidalgo Bayal nel panorama narrativo estremegno attuale

A lo largo de los últimos años, la narrativa extremeña ha producido un buen número de autores y obras cuya calidad destaca en el mundo de la literatura española. Entre otros, Luis Landero, Dulce Chacón, J.A. Gabriel y Galán y Eugenio Fuentes han aportado una importante contribución a las letras españolas de las últimas décadas. Gonzalo Hidalgo Bayal, autor que comparte con los antes citados el origen extremeño, se sitúa por ende en una generación literaria importante. La obra de este narrador, nacido en Higuera de Albalat y actualmente residente en Plasencia, no es muy conocida por el gran público. Sin embargo, no cabe duda de que los escritos de Bayal poseen unas calidades de primario valor. Su obra narrativa se puede dividir en dos agrupaciones principales. La primera es un grupo de narraciones breves, constituido por unas memorias (Campo de amapolas blancas), un conjunto de relatos fantásticos (La princesa y la muerte) y dos relatos brevísimos reunidos en un único volumen (El artista del billar). La segunda està formada por cuatro novelas: una es la interpretación moderna del cuento cervantino El celoso extremeño (Amad a la dama) y las demás (Misera fue, señora, la osadía, El cerco oblicuo y Paradoja del interventor) se desarrollan en época contemporánea, aunque en períodos distintos, y están protagonizadas por diferentes personajes. Al parecer es difícil encontrar un hilo conductor que valga para la entera obra del autor de Plasencia. Los diferentes desenlaces, un estilo que muda y protagonistas distintos proporcionan a los relatos hidalguianos cierta aptitud a la metamórfosis. Para comprender eficazmente la obra de Hidalgo hay que analizar, en primer lugar, su pensamiento estético: “En la literatura, a partir del primer fruto maduro, no hay evolución ni progresión, sino un deambular circular [...] las obras de un escritor son como satélites en torno a su materia” (El desierto de Takla Makán). Con referencia a uno de sus grandes maestros, Rafael Sánchez Ferlosio, el autor habla de la producción literaria como de un movimiento circular alrededor de una sustancia central. Esta sustancia central es constante: las diferentes obras del escritor pueden alejarse o acercarse a ella, describriéndola y descubriéndola con mayor o menor eficacia. Un análisis de la obra del propio Gonzalo Hidalgo debe entonces tener en cuenta de la necesidad de considerar esta materia central: relatos y novelas se mueven, formando un círculo que encierra una sustancia constante. Para investigar la materia alrededor de que la obra de Gonzalo Hidalgo se mueve, se han elegido dos téminos fundamentales del cuento. Lugar (o, mejor dicho, espacio) y personaje son ejes necesarios, cuya evolución puede proporcionar indicios sobre las lineas fundamentales que orientan el rumbo de la narrativa del autor. Se analiza entonces la manera en que Hidalgo describe y hace vivir espacios y personajes, y como estos se penetran recíprocamente. En algunos de los cuentos el autor utiliza un lugar (Murania) cuyas características físicas proceden de la realidad. La agrupación periférica de medio tamaño es el ambiente de la mayoría de los relatos de Gonzalo Hidalgo Bayal y la inspiración que la produce se encuentra en Plasencia, lugar de residencia del escritor. La función narrativa del espacio, de todas formas, varía y se hace cada vez más clara y precisa. Murania y los demás lugares realizan, con una evolución que atraviesa los distintos relatos, un rechazo firme e inapelable que excluye el personaje principal de la comunidad formada por los ciudadanos y, finalmente, por la entera humanidad. De forma cada vez más intensa, desde Misera fue, señora, la osadía hasta Paradoja del interventor (que constituye, por ahora, el punto de llegada del recorrido narrativo hidalguiano), el espacio actúa para excluir (y destruir) el protagonista, moral y físicamente. Manuel Simón Viola, en los estudios y en las reseñas dedicadas a Gonzalo Hidalgo Bayal, evidencia como el autor de Plasencia construye un trayecto que reúne sobre todo tres novelas (Misera fue, señora, la osadía, El Cerco oblicuo e Paradoja del interventor). Estas obras, además de tener algunas características comunes (conexiones temporales, temas, voz narradora), se centran en odiseas personales, protagonizadas por personajes distintos pero con un común denominador. El protagonista evoluciona hacia un pesimismo que se hace concreto en la relación con un mundo exterior, mundo que no permite ilusión nuguna. El fracaso inevitable con que el personaje se enfrenta es la única salida posible para los desenlaces del cuento hidalguiano. Al final de una evolución que incluye todos los personajes de la obra de Gonzalo Hidalgo, la resignación, principal característica del protagonista de Paradoja del interventor, se convierte en un rasgo distintivo. La derrota y el fracaso, por otro lado, funcionan de hilo conductor también en las obras de otros autores extremeños: Luis Landero y Dulce Chacón concentran, como Gonzalo Hidalgo, el esfuerzo literario en la descripción de afanes sin realizar. Con estilos y enfoques propios, comparten entonces una materia literaria que se descubre en la evolución del personaje y en la cada vez más clara definición de la función del espacio. La palabra, medio necesario para la trasmisión del mensaje literario, tiene entonces un valor fundamental. Como enseña Rafael Sánchez Ferlosio, a través del lenguaje el ser humano realiza su encuentro con la naturaleza: las relaciones humanas, el derecho, la ética y la literatura revolotean en torno al don de la palabra. El lenguaje literario es, como sugiere Gonzalo Hidalgo en algunos escritos críticos dedicados a la literatura extremeña, un vértice del tríangulo formado con sujeto y realidad. A través de las formas del lenguaje, elemento imprescindible, se expresa la relación entre persona y relidad exterior, entre yo y otro, entre personaje y espacio. En suma, el triángulo formado por lenguaje, sujeto y realidad es la clave para descubrir los mecanismos del “deambular circular” del escritor en torno a su materia.

Reconstructing Quantum Field Theory from an Educational Perspective

The research work concerns the analysis of the foundations of Quantum Field Theory carried out from an educational perspective. The whole research has been driven by two questions: • How the concept of object changes when moving from classical to contemporary physics? • How are the concepts of field and interaction shaped and conceptualized within contemporary physics? What makes quantum field and interaction similar to and what makes them different from the classical ones? The whole work has been developed through several studies: 1. A study aimed to analyze the formal and conceptual structures characterizing the description of the continuous systems that remain invariant in the transition from classical to contemporary physics. 2. A study aimed to analyze the changes in the meanings of the concepts of field and interaction in the transition to quantum field theory. 3. A detailed study of the Klein-Gordon equation aimed at analyzing, in a case considered emblematic, some interpretative (conceptual and didactical) problems in the concept of field that the university textbooks do not address explicitly. 4. A study concerning the application of the “Discipline-Culture” Model elaborated by I. Galili to the analysis of the Klein-Gordon equation, in order to reconstruct the meanings of the equation from a cultural perspective. 5. A critical analysis, in the light of the results of the studies mentioned above, of the existing proposals for teaching basic concepts of Quantum Field Theory and particle physics at the secondary school level or in introductory physics university courses.

La democrazia deliberativa negli Stati Uniti: teoria e prassi

This dissertation aims to analyse the development of the deliberative model of democracy in the U.S., both in an empirical and theoretical levels, from its origins in the eighties of the last century until now. In the first part we study the political and historical elements that build the crisis of the Liberal political system in the seventies in the U.S. and its effects on the political behaviour of citizens. In the second part we discuss the origins and development of the deliberative theory of democracy, its main authors, approaches and elements. The key aspect of this model of democracy is to reverse the apathy and strength the political participation of citizens through public deliberation. In the last part we expose the practical level of the deliberative democracy: how this theory of has been put into practice in the American political domain. We describe the main projects of deliberative democracy rose from civil society from the eighties until today. Finally, we expose the James Fishkin’s proposal of deliberative poll. This is the link between the empirical and theoretical levels of the deliberative model of democracy.

Inferences on earthquake kinematic properties from data inversion: two different approaches

During my PhD, starting from the original formulations proposed by Bertrand et al., 2000 and Emolo & Zollo 2005, I developed inversion methods and applied then at different earthquakes. In particular large efforts have been devoted to the study of the model resolution and to the estimation of the model parameter errors. To study the source kinematic characteristics of the Christchurch earthquake we performed a joint inversion of strong-motion, GPS and InSAR data using a non-linear inversion method. Considering the complexity highlighted by superficial deformation data, we adopted a fault model consisting of two partially overlapping segments, with dimensions 15x11 and 7x7 km2, having different faulting styles. This two-fault model allows to better reconstruct the complex shape of the superficial deformation data. The total seismic moment resulting from the joint inversion is 3.0x1025 dyne.cm (Mw = 6.2) with an average rupture velocity of 2.0 km/s. Errors associated with the kinematic model have been estimated of around 20-30 %. The 2009 Aquila sequence was characterized by an intense aftershocks sequence that lasted several months. In this study we applied an inversion method that assumes as data the apparent Source Time Functions (aSTFs), to a Mw 4.0 aftershock of the Aquila sequence. The estimation of aSTFs was obtained using the deconvolution method proposed by Vallée et al., 2004. The inversion results show a heterogeneous slip distribution, characterized by two main slip patches located NW of the hypocenter, and a variable rupture velocity distribution (mean value of 2.5 km/s), showing a rupture front acceleration in between the two high slip zones. Errors of about 20% characterize the final estimated parameters.

I doveri e le responsabilità contabili nella corporate governance delle società di capitali

La costruzione di un modello efficiente di corporate governance deve offrire una disciplina adeguata dei doveri contabili. Ciò nonostante, gli ordinamenti giuridici configurano i doveri di contabilità in modo incompleto, giacché l’inadempimento di questi non comporta una sanzione diretta per il soggetto inadempiente. Come informazione sulla situazione economica e finanziaria della società, esiste un interesse pubblico nella contabilità, e questa può servire come base di giudizio a soggetti interni ed esterni all’impresa, nell’adozione delle sue scelte. Disporre di un’informazione falsa o inesatta al riguardo può comportare un danno ingiustificato alla società stessa, ai soci o ai terzi, che potranno esercitare le azioni precise per il risarcimento del danno cagionato. Per evitare la produzione di questi danni, da una prospettiva preventiva, la corporate governance delle società di capitali può prevedere dei meccanismi di controllo che riducano il rischio di offrire un’informazione sbagliata. Questi controlli potranno essere esercitati da soggetti interni o esterni (revisori legali) alla struttura della società, ed avranno una configurazione diversa a seconda che le società adottino una struttura monistica o dualistica di governance. Questo ci colloca di fronte ad una eventuale situazione di concorrenza delle colpe, giacché i diversi soggetti che intervengono nel processo d’elaborazione dell’informazione contabile versano la sua attuazione sullo stesso documento: il bilancio. Risulta dunque cruciale determinare il contributo effettivo di ciascuno per analizzare il suo grado di responsabilità nella produzione del danno.

Le Coliti Microscopiche nei soggetti con diarrea non ematica: uno studio prospettico

Introduzione: le Coliti Microscopiche, altrimenti note come Colite Collagena e Colite Linfocitica, sono disordini infiammatori cronici del colon che causano diarrea e colpiscono più frequentemente donne in età avanzata e soggetti in terapia farmacologica. Negli ultimi anni la loro incidenza sembra aumentata in diversi paesi occidentali ma la prevalenza in Italia è ancora incerta. Scopo: il presente studio prospettico e multicentrico è stato disegnato per valutare la prevalenza delle CM in pazienti sottoposti a colonscopia per diarrea cronica non ematica. Pazienti e metodi: dal Maggio 2010 al Settembre 2010 sono stati arruolati consecutivamente tutti i soggetti adulti afferenti in due strutture dell’area metropolitana milanese per eseguire una pancolonscopia. Nei soggetti con diarrea cronica non ematica sono state eseguite biopsie multiple nel colon ascendente, sigma e retto nonché in presenza di lesioni macroscopiche. Risultati: delle 8008 colonscopie esaminate 265 sono state eseguite per diarrea cronica; tra queste, 8 presentavano informazioni incomplete, 52 riscontri endoscopici consistenti con altri disordini intestinali (i.e. IBD, tumori, diverticoliti). 205 colonscopie sono risultate sostanzialmente negative, 175 dotate di adeguato campionamento microscopico (M:F=70:105; età mediana 61 anni). L’analisi istologica ha permesso di documentare 38 nuovi casi di CM (M:F=14:24; età mediana 67.5 anni): 27 CC (M:F=10:17; età mediana 69 anni) e 11 CL (M:F=4:7; età mediana 66 anni). In altri 25 casi sono state osservate alterazioni microscopiche prive dei sufficienti requisiti per la diagnosi di CM. Conclusioni: nel presente studio l’analisi microscopica del colon ha identificato la presenza di CM nel 21,7% dei soggetti con diarrea cronica non ematica ed indagine pancolonscopica negativa. Lo studio microscopico del colon è pertanto un passo diagnostico fondamentale per il corretto inquadramento diagnostico delle diarree croniche, specialmente dopo i 60 anni di età. Ampi studi prospettici e multicentrici dovranno chiarire ruolo e peso dei fattori di rischio associati a questi disordini.

Global cities, global literature: New York e Tokyo nella narrativa contemporanea

Scopo del lavoro è quello di tracciare un parallelismo tra la narrativa giapponese e angloamericana contemporanea, viste come parte di un sistema di significati che trascende la dimensione nazionale e si installa invece in una dinamica di tipo globale. Le opere letterarie prese in considerazione sono alcune fra quelle ambientate nelle due vere e proprie capitali culturali dei paesi, rispettivamente New York per gli Stati Uniti e Tōkyō per il Giappone. Spunto di partenza dell’analisi è stato il concetto di “global city”, formulato dalla studiosa e sociologa Saskia Sassen, che permette di mettere in relazione dal punto di vista economico, strutturale ma anche sociale le città di New York e Tōkyō. Tale formulazione consente infatti di ragionare in maniera motivata sull’esistenza di un rapporto di flussi di scambio di tipo culturale e, parallelamente, sull’acquisizione di una dimensione di tipo transnazionale di soggetti e tematiche della letteratura. In questo senso, il rapporto tra economia e globalizzazione evidenziato da Sassen può essere paragonato a quello che intercorre tra la letteratura e la globalizzazione. Punto di snodo metodologico del lavoro è rappresentato dall’analisi dello spazio urbano, esaminato sia in chiave urbanistico-architettonica che più specificamente letteraria.

Proof theory of quantified modal logics

We introduce labelled sequent calculi for indexed modal logics. We prove that the structural rules of weakening and contraction are height-preserving admissible, that all rules are invertible, and that cut is admissible. Then we prove that each calculus introduced is sound and complete with respect to the appropriate class of transition frames.

Improvement of photon transport model by including coupled photon-electron transport and kernel refinement

The first part of this work deals with the inverse problem solution in the X-ray spectroscopy field. An original strategy to solve the inverse problem by using the maximum entropy principle is illustrated. It is built the code UMESTRAT, to apply the described strategy in a semiautomatic way. The application of UMESTRAT is shown with a computational example. The second part of this work deals with the improvement of the X-ray Boltzmann model, by studying two radiative interactions neglected in the current photon models. Firstly it is studied the characteristic line emission due to Compton ionization. It is developed a strategy that allows the evaluation of this contribution for the shells K, L and M of all elements with Z from 11 to 92. It is evaluated the single shell Compton/photoelectric ratio as a function of the primary photon energy. It is derived the energy values at which the Compton interaction becomes the prevailing process to produce ionization for the considered shells. Finally it is introduced a new kernel for the XRF from Compton ionization. In a second place it is characterized the bremsstrahlung radiative contribution due the secondary electrons. The bremsstrahlung radiation is characterized in terms of space, angle and energy, for all elements whit Z=1-92 in the energy range 1–150 keV by using the Monte Carlo code PENELOPE. It is demonstrated that bremsstrahlung radiative contribution can be well approximated with an isotropic point photon source. It is created a data library comprising the energetic distributions of bremsstrahlung. It is developed a new bremsstrahlung kernel which allows the introduction of this contribution in the modified Boltzmann equation. An example of application to the simulation of a synchrotron experiment is shown.