Photocatalytic water splitting using solar energy could contribute to the solution of environmental and energy issues related to the hydrogen production. Key research area in this field is the development of photo-catalyst able to provide high energy conversion efficiency. TiO2 has been mostly preferred material as the photo-electrode due to many advantages, mainly related to the cost factor and stability. We have studied on hydrogen production by water splitting in photo-electrochemical cells prepared by using photoanodes made by two different kinds of TiO2: one deposited by RF sputtering and the other one by sol-gel method. Depositions were performed on electrical conducting ITO whose electrical properties plays vital role to reduce the photon energy loss. The photoanodes have been characterised by several techniques to infer on their optical and compositional properties. The observed differences in hydrogen production have been attributed to the peculiarities in absorption properties of the two TiO2 films that in the case of sputter-deposited films are more prone to absorb radiation also because of the produced defects during the deposition process. Metals like Cr and Fe were doped in TiO2 by RF magnetron sputtering and sol-gel methods to increase the efficiency of hydrogen production by water splitting by sensitizing the doped-TiO2 in visible light spectrum. The doping method, dopant concentration, charge transfer from metal dopants to TiO2, and type of dopants used for modification of TiO2 were investigated for their ability to enhance photocatalytic activity. UV-Visible spectra show that the sputter-metaldoped- TiO2 films are much more efficient than the chemically-prepared samples to induce red shift of the absorption edge for absorbing visible light. In addition, we proved that dopant atoms must be located, at low concentration, near the ITO-TiO2 interface to avoid the formation of recombination centers for photo-generated electron-hole pairs. H2 production rate is higher with Fe-doped TiO2 (15.5 μmole/h) than with Cr-doped TiO2 (5.3 μmole/h) because Fe ions trap both electrons and holes thus avoiding recombination. On the other hand, Cr can only trap one type of charge carrier. To increase the light conversion efficiency and reduce the recombination processes of Cr-doped TiO2, a multilayer structure of ITO/Cr-doped-TiO2 (9 at.%) was developed. When the multilayer films were exposed to visible light, we observed that the photocurrent increases as function of the number of bilayers by reaching the maximum with 6-bilayers of ITO/Crdoped-TiO2. The enhanced photocurrent is attributed to: 1) higher absorption of visible light by Cr-doped-TiO2, 2) number of space-charge layers in form of ITO/TiO2 interfaces in multilayer films, and 3) generation of photoelectrons just in/or near to the spacecharge layer by decreasing the Cr-doped-TiO2 layer thickness. The superior photocatalytic efficiency of the 6-bilayers film implies higher hydrogen production rate through water splitting: we obtained indeed 24.4 μmole/h of H2 production rate, a value about two times higher than that of pure TiO2 (12.5 μmole/h). Similar experiment we performed by doing TiO2 with vanadium metal. With 6-ilayers vanadium doped TiO2 film Shows higher hydrogen production rate of about 31.2 μmole/h. This rate is higher than that of CR doped and pure TiO2. A constant H2 generation rate is obtained for long periods of time by all the investigated TiO2 films because of the separate evolution of H2 and O2 gas, thus eliminating the back-reaction effect. Even Ar+ or N+ ion implantation of energy 30 keV was adopted to vary the energy band gap of TiO2 film in order to absorb visible light.The original anatase phase was not changed by implantation. Increase in full visible absorption range was observed for both kinds of ion implanted-TiO2 films which further increases with the ion fluencies, while N+ ion implantation also causes the shift of the absorption edge from UV to visible light range. N+ implanted TiO2 showed narrowing of band gap from 3.2 eV for untreated anatase TiO2 to 2.78 eV for maximum implantation dose. The Ar+ and N+ implantation creates oxygen vacancies related defect energy level in the band gap. In case of N+ implantation, nitrogen also substitutionally replaces the oxygen atoms thus forming an energy level just above the valence band which further interacts with O 2p states resulting in the narrowing of band gap. The black solar absorber material develop over the copper target to absorb concentrated solar radiation and supply heat to the surrounding water. A black copper oxide layer was synthesized over copper substrate by using chemical oxidation treatment. We varied several treatment parameters and optimized the best condition to obtain a black textured layer which has the properties to absorb total solar radiation. The untreated polished copper showed 50 to 60 % reflectance (R) (incidence angle of 15o) and this value decreases to almost zero for whole wavelength range after formation of black copper oxide. The percentage absorption decreases by negligible amount as the angle of incidence increases. The SEM images of the copper oxide layer at high magnification showed a nano-petal like structure which causes the surface texture effect for higher absorption where surface irregularities such as grooves and pores with dimensions similar to the wavelength of the incident radiation simply increase the solar absorptance by multiple reflections. Long time thermal stability and corrosion resistance in hot water was also studied for the copper oxide film. The results revealed that the copper oxide was very stable and showed no changes in optical properties after the test. For the same water heating system a quartz window is used through which the solar radiation is transmitted on the copper target. Thus to acquire high power conversion efficiency it is necessary for quartz window to transmit the entire solar radiation incident on it without much lost due to the reflection on the surface. In general quartz window is able to transmit 90-91 % of the solar radiation while 1-2 % is absorbed and 7-8 % is reflected from the surface. Thus to have nearly complete transmittance it is necessary to cover the surface of quartz window with anti-reflecting (AR) coating: this was the part of my work. We developed single-layer and multi-layer AR coating for single specific wavelength and broad-band wavelength range respectively. Low reflective index material like MgF2 is deposited by e-beam technique to obtain single-layer AR coating. While Al2O3 and ZrO2 layers deposited, by RF-magnetron sputtering, on top of MgF2 forms multi-layer AR coating. The combination of MgF2/ZrO2/Al2O3/MgF2 deposited on both side of quartz showed excellent results with reflectance value of around 0.8% in broad spectral range. The heat exchanger efficiency obtained after using these developed black copper oxide absorber material and AR coating is around 83 % which seems to be significantly higher than the other commercially available water heating system. Concentrating solar power (CSP) systems are utilized to convert sunlight to thermal electric power by using solar absorber. However, the solar absorber are operated at elevated temperature (700-800 oC) and should be spectrally selective to act as perfect absorbers over the solar spectrum (high solar absorptance (α)) and perfect reflectors in the thermal infrared (IR) (low thermal emittance (ε)). Cermet composite solar absorber shows such selective properties at high temperatures. In the present work, we developed Al-AlN based multilayer cermet films by RF magnetron sputtering. We choose combination of Ni/AlxN(1-x)/AlN layers as a solar absorber due to its stability at elevated temperature and high corrosion resistance. In this combination, Ni layer, deposited near to substrate, act as the IR light reflector to provide high thermal emittance. While AlxN(1-x) layer act as an absorber layer for UV-Vis spectrum of solar radiation and transparent AlN layer on top functions as AR coating. To improve absorptance, 3 or 4 layers of AlxN(1-x) film with grading of metal content was synthesized by varying N2 flow during deposition. The optical measurement for these multilayer selective absorber films showed high solar absorptance of 0.92-0.96 and low thermal emittance of around 0.1-0.07. To test the stability of our multilayer coating at high temperature, we annealed these samples at 700 oC with holding time of 2 hrs in air, low vacuum and high vacuum. We observed a slight decrease in solar absorptance value (0.90) for the annealed samples but the results showed that overall performance was not hindered by heat treatment thus proving the thermal stability of our multilayer cermet coating.

In the present thesis two main results are presented. The first is a study of the statistical properties of the finite-time maximum Lyapunov exponent determined out of a time series by using the divergent rate method. To reach this goal, we developed a new, completely automatic algorithm based on the method developed by Gao and Zheng. A main achievement of this part of the work is the interpretation of the uncertainty in the light of the work by Grassberger, Badii e Politi of 1988 on the theoretical distribution of maximum Lyapunov exponents. We showed that the analysis and identification of clusters in diagrams representing uncertainty vs. maximum Lyapunov exponent can provide useful information about the optimal choice of the embedding parameters. In addition, our results allow us to identify systems that can provide suitable benchmarks for the comparison and ranking of different embedding methods. The second main result concerns the development of a new method for the assessment of the optimal embedding parameters. Our method is based on two assumptions: a potential-like quantity is defined on the lattice of points that characterize the embedding; the optimal embedding choice coincides with local extrema (maxima or minima) of this potential. Throughout the work, we used "synthetic" time series generated by numerically integrating the difference and differential equations that describe the following dynamical systems: the Hénon map, the Lorenz attractor, the Rössler attractor and the Mackey-Glass attractor. These four systems are widely used as references in the scientific literature. In the last part of the work, we have started to examine EEG recordings by using the techniques developed in the main part of the work. The EEG recordings are sampled on healthy subjects in resting-state. These investigations are still at a starting phase.

Si tratta di una ricerca sui fattori che intervengono nell'apprendimento della matematica, a livello scolastico secondario di II grado, condotta attraverso un'analisi delle convinzioni, intese come attitudini, attribuzioni, aspettative e stereotipi. La ricerca mette in luce i processi interazionali che intervengono nel concetto di sè matematico, negli stili attribuzionali di successo e insuccesso e nella socializzazione, primaria e secondaria, ai ruoli di genere.

Simulating rare structural rearrangements of macromolecules with classical computational methods, such as Molecular Dynamics (MD), is an outstanding challenge. A multitude of technological advancements, from development of petaFLOPS supercomputers to advent of various enhance sampling methods, has granted access to time intervals of microseconds and even milliseconds in recent years. Yet, many key events occur on exponentially longer timescales. Here, path sampling techniques have the advantage of focusing the computational power on barrier-crossing trajectories, but generating uncorrelated transition paths that explore significantly different conformational regions remains a problem. To address this issue, we devised a hybrid path-sampling scheme, graph-Transition Path Sampling (gTPS), that generates the trial transition pathways using a quantum annealer. We first employ a classical computer to perform an uncharted exploration of the conformational space using a data-driven MD method. The dataset is then post-processed using a path-integral-based method to obtain a coarse-grained network representation of reactive pathways. By resorting to quantum annealing, the entire ensemble of these pathways can be encoded into a superposition in the initial quantum state of the annealer. Finally, by performing the quantum adiabatic transition on the state of the annealer, one can potentially generate/sample uncorrelated paths while they retain a high statistical probability (follow low free energy regions). We have first validated this scheme on a prototypically simple transition (α_R↔C_5 of alanine dipeptide) which could be extensively characterized on a desktop computer. Subsequently, we scaled up in complexity by generating a protein conformational transition (Bovine Pancreatic Trypsin Inhibitor - BPTI) that occurs on the millisecond timescale, obtaining results that match those of the Anton special-purpose supercomputer. Finally, we dicuss our current investigations on the application of gTPS to the unfolding process of headpiece subdomain of Villin and BPTI. Despite limitations due to the available quantum hardware, our study highlights how realistic biomolecular simulations provide a potentially impactful new ground for applying, testing, and advancing quantum technologies.

La ricerca tratta il tema delle modificazioni del corpo (piercing, tatuaggio, scarificazione, chirurgia estetica) nelle sue implicazioni con la questione dell'identità di genere. Attraverso uno studio sul campo condotto con metodo etnografico e interviste in profondità, vengono indagate in chiave etnometodologica le procedure attraverso cui i soggetti elaborano ed esprimono il proprio self in relazione alle rappresentazioni sociali condivise relative alla mascolinità e alla femminilità. / This research is about body modification techniques (piercing, tattooing, scarification, aesthetic surgery) in relation to gender identity. By means of a fieldwork carried out with ethnographies and in depth interviews, procedures of elaboration and expression of individual self are investigated, via an etnomethodological approach, and in a relation to social representations of femininity and masculinity.

La presente ricerca ha analizzato il fenomeno dei blog giornalistici per rilevare se, nonostante sia impossibile riscontrare la perfetta corrispondenza tra testi di informazione ed eventi del mondo reale, l'intervento dei lettori può fare comunque in modo che si verifichi, attraverso la condivisione dei contenuti dell'informazione, un sostanziale accostamento alla verità dei fatti così come essi sono accaduti. Tutto ciò permette ai giornalisti di diffondere un'informazione più precisa, più completa e meno manipolata. Sono state discusse le ragioni del giornalismo oggettivista e quelle del giornalismo esplicativo ed è emerso come, nei blog analizzati, siano presenti due metodi diversi in grado di garantire una maggiore oggettività dell'informazione. Ciò accade perché i lettori possono interagire confrontando opinioni tra loro diverse. Dall'analisi dei post degli autori dei blog Marcello Foa e Beppe Grillo e dei relativi commenti dei loro lettori, è emerso come il valore aggiunto di questi interventi risieda nel fatto che i lettori non si rivolgono solo al giornalista, in questo caso variando di poco la dinamica, per esempio, dell'invio di lettere alla redazione, ma si rivolgono ad altri lettori per informarli o per chiedere loro spiegazioni e chiarimenti. / The research analyses the phenomenon of j-blogs to investigate if, in spite of the impossibility to achieve the perfect conformity between information about facts and facts in themselves, the participation of readers can operate, through the sharing of information contents, to assure an approach more accurate to reality and truth of events. This allows journalists to divulge an information more correct, and less manipulated. The reasons of journalism that explains facts and journalism that only describes them without any interpretation about, were equally examined. The research discovered that, in the two blogs analysed, it's possible bring out two different methods able to guarantee a major information objectivity. This occurs because readers can interact comparing different opinions. From the analysis of Marcello Foa and Beppe Grillo blogs and from their readers' comments, came out that the potential benefits of these interactions follow the possibility for readers to interact not only with journalist, in this case acting as traditional readers who, for example, send letters to the editorial staff, but also with other readers to inform them or to receive from them explanations or clarifications.

Oggetto di questo lavoro è lo studio dello scandalo politico come costruzione mediatica, dalla notizia alla comunicazione dell’evento. L’individuazione dei temi sensibili e la ricostruzione delle retoriche dello scandalo politico italiano, avverrà tramite una ricognizione del dato giornalistico delle principali testate del Paese. La trasformazione di un fatto in scandalo è spesso strumento della competizione politica, utile alla messa in crisi della reputazione, della stima e della fiducia, quali caratteristiche indispensabili di ogni leader politico. L’accentuata relatività del confine tra spazio pubblico e privato, unitamente all’invadenza dei media, contribuiscono poi alla vulnerabilità della sua immagine. L’obiettivo è quello di utilizzare lo scandalo come lente di ingrandimento della relazione fra politica e media, rispetto alla contesa del potere per la gestione della notizia, tramite cui si è in grado di influenzare la percezione pubblica dei fatti politici. Come la politica è la politica dei media, come la politica gestisce i media e come i media gestiscono la politica, è il risultato dell’analisi. I tre casi scelti sono collocati nel periodo successivo al governo Prodi (2006-2007): lo scandalo della “droga in Parlamento”, quello legato al nome di Scaramella e alla Commissione Mitrokhin, ed infine il caso “Sircana” all’interno dell’inchiesta Vallettopoli. / Object of this work is the study of political scandal as a media creation, from news to the communication of event. The rhetoric of political scandal in Italy and the sensitive topic are analyzes through journalistic information of the main national heading. The transformation of fact in scandal is often a tool for political competition, as useful for critically damage the reputation, esteem and trust as fundamental characteristics of a political leader. The increased relativity of the threshold between public and private spaces and the pervasive nature of media, contribute to the vulnerability of his image. The objective is utilize the scandal as a magnifying glass for the relation between politics and media, with respect to contention of the news management power, for the final influence of public perception of political facts. How politics are media politics, how politics manage the media, and how media manage politics, is the result of my analysis. Case studies include three scandals exploded during the last govern Prodi (2006-2007): “drug in Parliament”, the scandal regarding “Scaramella e la Commissione Mitrokhin” and the case of “Sircana”, inside the investigation of Vallettopoli.

Il presente lavoro di tesi si propone di ricostruire le “logiche mediali” dell’editoria promossa dalle minoranze etniche attraverso un approccio etnografico. Nella prima parte si ricostruisce lo scenario mediale, culturale, istituzionale entro il quale si dipanano le attività editoriali, con particolare attenzione alle profonde trasformazioni indotte dalle dinamiche globali e dalle migrazioni internazionali. Nella seconda parte, si ricostruisce il dibattito sulle culture mediali etnico-minoritarie a partire dall'analisi dei contributi più significativi, con un approfondimento meta-teorico sugli approcci metodologici più ricorrenti e, infine, la descrizione della realtà editoriale italiana. Nella terza parte, si indaga il significato del processo di framing in relazione alla capacità dell’istituzione giornalistica di fornire definizioni della situazione sociale e, al contempo, produrre un allargamento delle forme di cittadinanza. Nella quarta e ultima parte, si espongono i risultati di una ricerca etnografica che ha coinvolto un campione composto da sei redazioni impegnate nella produzione di contenuti televisivi. Dall’indagine qualitativa emerge una panoplia di culture produttive, in cui la professionalità e l’etnicità del soggetto vengono ri-negoziate sulla base delle peculiarità di ciascun assetto produttivo. Nondimeno, le culture mediali etnico-minoritarie rappresentano un punto d’osservazione privilegiato dal quale cogliere le complesse dinamiche che investono il mediascape contemporaneo nell’epoca della convergenza. / The dissertation is an attempt to reconstruct ethnic minority publishing media logic through an ethnographic approach. The first part is a depiction of the media, cultural, institutional scenario, where publishing practices unfold, with a specific focus on meaningful transformations provoked by both global dynamics and international migrations. The second part is a reconstruction of the debate upon ethnic media culture, or rather, an analysis of the most salient approaches and a meta-theoretical examination of the most recurring methodologies. The third part provides an insight on the process of framing with relation to the journalism, and the possibility to offer a definition of the social situation and to produce an enlargement of the concept of citizenship. The fourth part is a presentation of the ethnographic results of a research upon a sample compounded by six newsroom. Qualitative outcomes reveals a huge range of productive cultures, in which both professionalism and ethnicity are negotiated in base of the specific features of each organization. Nevertheless, ethnic minority media culture represents a privileged viewpoint from where to observe the complex dynamics affecting the contemporary mediascape in the convergence era.

La tesi affronta la questione delle culture civiche presenti su internet a partire dal dibattito teorico sulla rete e le sue implicazioni in relazione al discorso e alla prassi politica. Nella prima parte verranno messi in luce i presupposti delle riflessioni più recenti che tematizzano la possibilità che il web, in quanto luogo di discussione e partecipazione tendenzialmente libero e inclusivo, possa rappresentare l’incarnazione del modello idealtipico di sfera pubblica borghese, magistralmente elaborato da Habermas (1962). Grazie all’interattività, ai bassi costi di produzione e distribuzione, a una nuova struttura di comunicazione many-to-many, le nuove tecnologie digitali sembrerebbero consentire la realizzazione di una intersoggettività pura, autenticamente orientata all’intesa reciproca e non contaminata dall’agire strumentale dei sistemi politici ed economici. Tuttavia, se si analizzano le ricerche empiriche finora condotte (tra gli altri Whilelm 1999, Tsaliki 2002, Wright e Street 2007), si osserva che, accanto a contributi che evidenziano una notevole capacità deliberativa delle discussioni online, ne esistono altrettanti che, al contrario, mettono in luce un gap profondo tra l’ideale normativo e la prassi concretamente messa in atto. Attraverso un doppio binario, induttivo e deduttivo, si tenterà di provare come la contraddittorietà radicale di tali risultati empirici sia in ultima istanza riconducibile alle problematicità insite nel modello habermasiano e alla sua inadeguatezza nel cogliere la complessità dei processi della partecipazione politica che hanno luogo sulla rete. A partire da questa constatazione, si dimostrerà come la sua applicazione possa ancora essere feconda a patto che si ipotizzi di considerare l’ideale di sfera pubblica habermasiano come uno dei paradigmi che ancora informano gli immaginari sociali moderni (Taylor, 2005), piuttosto che come ideale contro-fattuale (Dryzek, 1990) rispetto al quale commisurare criticamente le imperfezioni del reale. Ne discenderà una traslazione della prospettiva analitica, sintetizzabile nel passaggio da un approccio normativo – prescrittivo, rigidamente ancorato a una determinata concezione del “dover-essere”, a un approccio culturale - diagnostico che invece indaga la contingenza del reale alla luce delle sue precondizioni sociologiche e culturali (Nieminen, 2006). Nella seconda parte, si analizzerà il caso empirico del blog curato dal comico italiano Beppe Grillo (www.beppegrillo.it) attorno al quale si è sviluppato un movimento politico altamente articolato ed eterogeneo, capace di promuovere incursioni sempre più frequenti nella politica istituzionale. L’analisi empirica scaturirà dall’applicazione di un modello analitico che attinge al paradigma delle culture civiche proposto da Dahlgren (2009) e in parte lo riformula alla luce del concetto di mediazione sviluppato da Silverstone (1999). Attraverso l’analisi del contenuto dei post del blog e di un corpus di interviste realizzate su lettori del blog e attivisti del movimento, si tenterà di dimostrare come il fenomeno sviluppatosi attorno a Beppe Grillo abbia funzionato come una “public sphericule” (Gitlin, 1998), una piccola sfera pubblica capace di maturare una propria cultura civica, contraddistinta da autonomi processi di mediazione e di valorizzazione del quadro socio-tecnologico a disposizione. / The notions of deliberation and the frame of the discourse theory of democracy (Habermas, 1996), have inspired a substantial strand of studies focused on the internet’s democratic potential (See e.g. Kellner (1999), Rheingold (1993), and Wilhelm (1999)). The central accomplishment of these various contributions lies in the assessment of the extent to which dialogical exchanges taking place in the cyberspace conform to the normative requirements of the ‘counter-factual ideal’ of public sphere (Dryzek, 1990). However, the contradictions that appear when analyzing practical research findings from a comparative global view, pose a dilemma that deals more with theoretical assumptions rather than with the empirical methods applied. The basic aim of the thesis will be the proposal of a cultural turn in the analysis of online public spheres, inspired by the model of “civil cultures” developed by Dahlgren (2009). For this purpose, two major lines of reasoning will be developed. On one hand, the theoretical roots of the concept of deliberation and the long wave of criticisms drawn out by them, will be explored in order to underscore the intrinsic shortages of the notion. It will be argued that the model of “civic cultures” seems to offer a more adequate analytical frame in order to make sense of the pluralized and fragmented online environment. In fact, its original assumptions offer a real antidote to technological determinism. If it is true that technology only makes sense within a social context from which it receives symbolic and pragmatic meanings (Lievrouw, 2002), we can think of civic cultures as a ‘community of practices’ (Wenger, 1998) within which specific ways of using and interpreting technologies are carried out in order to achieve political and civic purposes. On the other hand, the theoretical path will be supported by the references to an empirical case study that will show how the model can be conveniently used to study what is concretely happening in the living public spheres of the internet. The case study will be focused on Beppegrillo.it, an Italian weblog acting as a communicative platform for the development of a civic and political movement which is lead by Beppe Grillo, a well-known comedian.

Il sistema dell’informazione italiano vive oggi un periodo di profonda crisi, che molti osservatori definiscono come crisi di credibilità: il pubblico non sembra infatti fidarsi dei news media tradizionali e preferisce cercare altrove le proprie fonti di informazione (blog, social network, ecc,); i giornalisti non sempre percepiscono la scarsa fiducia del pubblico, e tendono talvolta a chiudersi nella propria autoreferenzialità. La ricerca indaga il problema della credibilità, tanto dei media tradizionali quanto dei digital media, distinguendo tra credibilità della notizia e credibilità del giornalista, e individuando nel metodo, nel linguaggio, nella formazione e nella responsabilità gli strumenti cui il sistema dell’informazione può fare ricorso per recuperare la fiducia del pubblico e, con essa, la propria credibilità. / Nowadays Italian news system is experiencing a period of radical crisis, that it’s defined by several observers as a “credibility crisis”: people don’t seem to trust in traditional news media and prefer to look elsewhere for the sources of their information (blog, social network, etc.); journalists don’t always perceive the lack of public trust, and sometimes they tend to be locked in their own self. The research investigates the problem of credibility (related to mainstream media and digital media) distinguishing between news credibility and the journalist’s credibility. Method, language, training and responsibility are the main tools that the news system can use to recover people’s trust and its credibility.