Monte Carlo Simulations of Electron Transport in 3D Solids and Molecular Dynamics Simulations of the Mechanics of 2D materials

The aim of this thesis is the study of electronic transport and mechanical properties of materials using computer simulations. In particular, we dealt with the charge transport in semiconduc- tor and metallic samples and with the peeling of a graphene layer from bulk graphite. The computational methods used to investigate the samples are (i) the Monte Carlo (MC) statis- tical method to simulate the transport of electrons in solids and (ii) the molecular dynamic (MD) approach to study the mechanical characteristics. A relevant part of this thesis is focused on carbon-based material, such as diamond and graphite, and the stable two-dimensional al- lotrope, graphene. The response of diamond and graphite to external electromagnetic pertur- bations, due to e.g. an impinging electron beam, was investigated by calculating reflection electron energy loss (REEL) spectra with MC simulations. By comparing the calculated spec- tra, obtained using different dielectric models, and in-house recorded experimental results, the most effective dielectric model better describing the plasma losses was identified. Moreover, an extension to these models to describe the anisotropic response of graphite to an external electromagnetic perturbation was developed and included in the MC approach. Owing to the central role of carbon for future electronic and technological applications, also its mechanical properties were investigated by means of MD simulations. In particular, the peeling process of a layer of graphene from a bulk of graphite was investigated. This process is exploitable for graphene production and for adhesive applications of this material. Moreover, the MC approach, employed for calculating REEL spectra, was tested and compared to other com- putational techniques based on the solution of the Ambartsumian-Chandrasekhar equations. This consistency test was realized by considering three metals (copper, silver and gold) as tar- get materials. Further studies were carried out on these materials by calculating secondary electron emission yields as a function of the electron beam energy. A remarkable good agreement with experimental data was obtained. The MC approach was also used to investigate the growth of particles in a W(CO)6 layer deposited on a SiO2 substrate upon irradiations by an electron beam in the context of the focused electron beam induced deposition technique. In particular, by applying the MC method, the radial distribution of emitted secondary electrons was calculated and then utilized as input data for further MD simulations. Moreover, the study of electron transport in an organic polymer (P3HT) was performed in order to understand how the molecular ordering affects the secondary electron emission. This aspect is of paramount importance to construct efficient organic electronic devices

The Fog and the Cloud: The emergence and development of social incubators in cities. An analysis of the urban geography of social innovation

The creation and support of an ecosystem of social incubators has been analysed in organizational research with regards to business models, services provided and financial performances’ evaluation (Giordano et al., 2015). How these ecosystems are created, the peculiarity of third sector as well as the role of social innovation is a debated topic in social economy. Social incubators are substantially different from the technological incubators for motivations, relations and processes of the firms and actors involved. They are intrinsically bonded to the local systems where they are usually established by virtue of local institutions. However, the local impacts of these new typology of organizations have not yet been systematically investigated, leaving the topic uncovered by economic geography. Social incubators are located in cities, close or incorporated into knowledge hubs such as universities or in zones with relevant level of inequalities, for developing innovations answering local social needs, engineering social innovation. Community social networks are reproduced to satisfy human needs and social empowerment, their relationship being explained by the geographical perspective of social innovation (Van Dyck and Van den Broeck, 2013). Despite its recognized key role in development, geography approach to social innovation still remain extremely vague (Van Dyck and Van den Broeck, 2013). The objective of this dissertation is to provide a first set of answers to that gap involving the urban environment of the city of Milan and a subsequent comparative case strategy with incubators in Brussels

Numerical and experimental methods for seismic risk assessment of civil and industrial structures

Due to high seismic vulnerability and severity of possible failure consequences, petrochemical installations are often considered as “special risk” plants. Although tanks, pipes, elbows and bolted flanges have been a major concern in terms of seismic design, generally, they have not been analysed with modern performance-based procedures. This thesis will explore some important themes in seismic risk assessment with a special focus on petrochemical plants and components. In the first part of the thesis the case study of a probabilistic seismic demand analysis (PSDA) for a Refrigerated liquefied gas (RLG) subplant is presented. As a matter of fact, RLG terminals that are part of strategic facilities must be able to withstand extreme earthquakes. In detail, a liquefied natural gas (LNG, ethylene) terminal consists of a series of process facilities connected by pipelines of various sizes. In this study, the seismic performance of pipes, elbows and bolted flanges is assessed, and seismic fragility functions are presented within the performance-based earthquake engineering framework. Particular attention is paid to component resistance to leakage and loss of containment (LoC) even though several different limit states are investigated. The LNG tank, support structures and pipework, including elbows and flanges, are analysed with a detailed 3D finite element model. For this purpose, a mechanical model of bolted flange joints is developed, able to predict the leakage limit state, based on experimental data. A significant effort is also devoted to identification of a leakage limit state for piping elbows, and the level of hoop plastic strain was found to be an indicator. The second part of the thesis describes an innovative methodology to evaluate seismic performances of a realistic tank-piping system with special focus on LoC from piping elbows. This methodology relies on a set of experimental dynamic tests performed throughout hybrid simulations where the steel storage tank is numerically modelled while, conversely, the physical substructure encompasses the coupled piping network. Besides, ground motions for dynamic tests are synthetized based on a stochastic ground motion model whose input parameters are derived from the results provided by a seismic hazard analysis. Then, based on output data from the experimental tests, both a high-fidelity and a low-fidelity FE model are calibrated. Furthermore, these models are used to run additional seismic analyses using a large set of synthetic ground motions. Moreover, in order to derive the seismic response directly from inputs parameters of the stochastic ground motions model, the procedure to build a hierarchical kriging surrogate model of the tank-piping system is presented. Eventually, the surrogate model can be adopted to perform a seismic fragility analysis. Along with the line of probabilistic analysis, another contribution to this research work is a probabilistic seismic demand model (PSDM) of a steel-concrete composite structure made of a novel type of high-strength steel moment resisting frame. According to the main topic of this thesis, the procedure that is here presented can be used either in a seismic risk assessment or a fully probabilistic performance-based earthquake engineering (PBEE) framework. In detail a 3D probabilistic seismic demand analysis was performed considering the variability of the earthquake incident angle, generally not taken in account in typical fragility analyses. Therefore, the fragility curves evaluated following this approach account for the uncertainty of both the seismic action and its direction

Gaze data reveal adaptive mechanisms of strategy generation in judgment and decision making

Human beings must constantly adapt to an uncertain and mutable world by generating efficient behavioral strategies to pursue their goals. The complexity of this task increases in interactive contexts, where the outcomes of our actions depend also on the choices of other agents. When the environment does not provide reliable feedback, the effectiveness of behavioral strategies rests on the ability to handle available knowledge: agents have indeed to extract relevant information from noisy signals and build an exhaustive representation of the set of potential actions and outcomes available to themselves and to others. Individual differences in the implementation of these information- processing operations may underlie behavioral heterogeneity in several judgment and decision making tasks. Here we report three eye-tracking studies revealing the existence of distinct information-processing strategies in different individuals. Study 1 explores inter-individual differences in the generation of relational representations of interdependent contingencies. In Study 2 and Study 3, we move towards social contexts to investigate the mechanisms of strategy generation underlying strategic behavior in interaction. Our findings indicate that gaze data can disclose individual differences in the process of spontaneous strategy generation in both individual and interacting settings. We also report results suggesting that the emergence of unsophisticated information-processing strategies is associated with cognitive style. Moreover, we show that the attentional mechanisms sustaining the generation of unsophisticated strategies can be reconsidered and updated under the impact of endogenous and exogenous cues revealing the existence of alternative information-processing behaviors

Impact of ETV7 on chemoresistance and cancer stem-like cell plasticity in breast cancer

ETV7 is a poorly characterized transcriptional repressor that belongs to the large family of ETS transcription factors, whose members have been associated with several cancer-related processes. ETV7 is a well-recognized Interferon-stimulated gene (ISG), and it was shown that its expression can be synergistically induced by the combined treatment with the chemotherapeutic drug Doxorubicin and the inflammatory cytokine TNFa in different cancer cell lines, including the breast cancer-derived MCF7 cells. Recently, it has been shown that ETV7 expression is significantly increased in breast cancer tissues, compared to the normal breast; however, the roles and the impact of ETV7 expression in breast cancer have still to be elucidated. This project aimed at understanding the effects caused by increased ETV7 expression on breast cancer (BC) progression and resistance to conventional anti-cancer drugs. We first observed that ETV7 expression can be induced by different stimuli, particularly by the treatment with several chemotherapeutic drugs able to induce DNA damage. We also demonstrated that the expression of ETV7 could affect the sensitivity of BC cell lines to standard anti-cancer therapies, such as Doxorubicin, 5-Fluorouracil and radiotherapy, and this evidence was correlated with an increase in ABC transporters and anti-apoptotic proteins expression. By investigating the possible mechanism responsible for ETV7-dependent Doxorubicin resistance we identified a novel target gene of ETV7, DNAJC15, which is a co-chaperone protein whose repression was previously associated with drug resistance. Given the ability of cancer stem cells (CSCs) to be more chemoresistant, we analyzed the effects of ETV7 expression on the sub-population of breast CSCs. We found that ETV7 expression could exert a strong effect on breast cancer cells stemness, confirmed by both an increase in CD44+/CD24low population and mammosphere formation efficiency. In order to investigate the mechanisms responsible for these effects, we performed an RNA-seq analysis, which revealed significant repression of a signature of Interferon-stimulated genes, suggesting a possible negative feedback mechanism in the regulation of the response to Interferon. Finally, prolonged treatment of breast cancer cells with IFNb was able to rescue the effects on CSCs content. Taken collectively, our data revealed that ETV7 can affect the sensitivity of breast cancer cells to some chemotherapeutic drugs and we propose ETV7 as an important contributor to the tumor-initiating capabilities of BC cells

Knowledge Network Structures and Dynamics in Local Systems: Evidence from the Wine Industry.

Among the advantages of belonging to successful local systems like clusters, the regional economic literature has stressed the critical role played by localized knowledge. For some time, scholars have been arguing that knowledge spreads unevenly among local actors, rather than pervasively and widely, but, its drivers, underlying social structure, and evolution over time remain poorly understood. Particularly, on the one hand, heterogeneity of firms and the way they are perceived are fundamental features to understand evolutionary patterns of clustered firms acting in a world of uncertainty and imperfect information; on the other hand, different ties among the same set of actors simultaneously diffuse specific knowledge. This PhD thesis aims to go deeper in this debate investigating a framework to study local development in relation to architectures and dynamics of local systems and focussing on a network perspective; particularly, stressing the role of both individual heterogeneity and relational multiplicity; testing the efficacy of the identified framework within the same industry, but, with two different and original databases; implementing two different methodologies of social network analysis for the study of knowledge network structures and dynamics (Exponential Random Graph Models and Stochastic Actors Oriented Models); and identifying a few policy implications. To organically achieve these aims, the thesis aims to answer the following general research questions: What is the state of the art of knowledge networks within local systems? To what extent do multiple ties as different relational sets through which knowledge diffuses impact on the local exchange of knowledge? To what extent does status as the perceived relative qualities of a firm in a given market or organizational field affect knowledge network evolution over time? To answer these questions, the first chapter “Knowledge Networks within Local Systems. Their Structures and Dynamics” provides a literature review on knowledge network structures and dynamics within local systems and it offers an original explanation of local systems evolution with a knowledge network perspective. The second chapter “Complementary Inter-Firm Relations of Multiple Knowledge Networks in Industrial Clusters: Evidence from a Growing Wine Cluster in Italy” shows that different kinds of relationships positively impact on the spread of technical knowledge, but they are different in magnitude and they follow complementary patterns rather than substitutive ones. The third chapter “Status and the Assortative Dynamics of Knowledge Networks in Industrial Clusters: Evidence from a Successful Wine Cluster in Italy” shows the presence of an assortative network change, where high-status firms are more likely to interact with other high-status firms but not with low-status firms (and vice-versa). Finally, the last part concludes with a summary of the main findings and it offers a few possible policy implications. Also, the main limitations of the study as well as a few future possible extensions are discussed

Eye controlled semi-Robotic Wheelchair for quadriplegic users embedding Mixed Reality tools

Mobile assistive robotics can play a key role to improve the autonomy and lifestyle of patients. In this context, RoboEye project aims to support people affected by mobility problems that range from very impairing pathologies (like ALS, amyotrophic lateral sclerosis) to old age. Any severe motor disability is a condition that limits the capability of interacting with the environment, even the domestic one, caused by the loss of the control on our own mobility. Although these pathologies are relatively rare, the number of people affected by this disease are increasing during the years. The focus of this project is the restore of persons’ mobility using novel technologies based on the gaze on a power wheelchair designed to enable the user to move easily and autonomously inside his home. A novel and intuitive control system was designed to achieve such a goal, in which a non-invasive eye tracker, a monitor, and a 3D camera represent some of the core elements. The developed prototype integrates, on a standard power wheelchair, functionalities from the mobile robotics field, with the main benefit of providing to the user two driving options and comfortable navigation. The most intuitive, and direct, modality foresees the continuous control of the frontal and angular velocities of the wheelchair by gazing at different areas of the monitor. The second, semi-autonomous, enables the navigation toward a selected point in the environment by just pointing and activating the wished destination while the system autonomously plans and follows the trajectory that brings the wheelchair there. The main goal is the development of shared control, combining direct control by the user with the comfort of autonomous navigation based on augmented reality markers. A first evaluation has been performed on a real test bed where specific motion metrics are evaluated. The designs of the control structure and driving interfaces were tuned thanks to the testing of some volunteers, habitual users of standard power wheelchairs. The driving modalities, especially the semi-autonomous one, were modelled and qualified to verify their efficiency, reliability, and safety for domestic usage

Prosecutorial Discretion and its Judicial Review at the International Criminal Court: A Practice-based Analysis of the Relationship between the Prosecutor and Judges

The permanent system of international criminal justice created through the Rome Statute envisages a wide margin of discretion for prosecutorial action, under the constraint of various forms of judicial supervision. Nevertheless, legal texts provide only very limited guidance to the Office of the Prosecution and judges as to the concrete exercise of these powers and responsibilities. For this reason, prosecutorial and judicial dynamic practice plays a fundamental creative role in integrating—and sometimes transforming—the ICC static legal framework. The present research has aimed at analysing the patterns of prosecutorial and judicial practice at the pre-trial stage of the proceedings of the ICC, with a view to comparing the law in the books and the law in action in this area of crucial importance for the legitimacy of the Court. The hypothesis that in this field there are areas of interpretive agreement (smooth relationship) and disagreement (open clash) between the relevant actors, as well as a certain degree of dissociation between the textual formant and the prosecutorial/judicial formant has been tested against the relevant practice. These empirical phenomena have then been assessed as to their possible institutional causes and (potentially detrimental) consequences, with a view to proposing institutional, procedural, administrative and legislative adjustments that may help fostering the predictability and consistency of the system. The conclusion is that practice in this field is a fundamental test-bench for the institutional functioning of the ICC, and that it is still in the process of establishing— by means of the interplay between the OTP and judges—a satisfactory balance among the conflicting needs of flexibility and predictability; one that only pragmatic interpretive compromises can bring about in the future

The perception of intonation in native and non-native linguistic contexts and by different individuals: From question-answer categorization to the integration of prosody and discourse structure

This thesis addresses the cognitive foundations of categorization and acquisition of intonational categories in native (L1) and second language (L2). It focuses on the link between the processing of intonational categories and the and pragmatic functions of language. The thesis reports two behavioral psychoacoustic experiments that studied the disambiguation of sentence-modality (statement vs. question) signaled by sentence-final Boundary Tones by manipulating lexical and linguistic status of the underlying segmental information. A third ERPs experiment studied with ERPs the association of specific Pitch Accents with the discourse status of a referent in German and how different processing-correlates of PA violation are processed in L1 and L2 speakers. In all experiments, specific attention has been devoted to individual differences both at the theoretical and empirical level. I showed that perceivers can display variability in processing as a function of biographic factors, in the quantity and quality of training in a second language, and in the presence of variables related to the construct of Theory-of-Mind (ToM). I support the view that the processing of intonational categories, modulated by Fundamental Frequency contours, links with the processing of segmental information, the semantic access at word-level, and the decoding of the information structure within the discourse model. The study of processing of pitch contours is a highly multidisciplinary discipline, but the different theoretical perspectives are not always considered within specific research. I propose to approach the study of pitch processing by trying to integrate the different theoretical and empirical approaches with the aim to use the available knowledge. This broader perspective considers the auditory categorization process, the integration of the sound-domain information with higher-order linguistic structure, and the modeling of individual variability of the perceivers. I support the view that the presence of individual traits that favor the efficient decoding of the interlocutor’s perspective and intentions correlates with a more efficient processing of the discourse information structure. I propose that this is observable through the manipulation of the associated intonational categories. I think that the adoption of a multidisciplinary perspective, centered on the processing of intonational categories, and the approach developed in this thesis is relevant to develop further the study of specific populations known to display less efficient processing of the pragmatic aspects of discourse, such as individuals with Autism Spectrum Conditions

Simple objects in the heart of a t-structure

Historically, the study of modules over finite dimensional algebras has started with the study of the ones with finite dimension. This is sufficient when dealing with a finite dimensional algebra of finite representation type, where there are only finitely many indecomposable modules of finite length. Indecomposable modules of infinite length occur when dealing with algebras of infinite representation type and the study of pure-injective modules over a finite dimensional algebra is crucial for the problem of describing infinite dimensional modules. In this talk, we consider a specific class of finite dimensional algebras of infinite representation type, called "tubular algebras". Pure-injective modules over tubular algebra have been partially classified by Angeleri Hügel and Kussin, in 2016, and we want to give a contribution to the classification of the ones of "irrational slope". In this talk, first, via a derived equivalence, we move to a more geometrical framework, ie. we work in the category of quasi-coherent sheaves over a tubular curve, and we approach our classification problem from the point of view of tilting/cotilting theory. More precisely, we consider specific torsion pairs cogenerated by infinite dimensional cotilting sheaves and we study the Happel-Reiten-Smalø heart of the corresponding t-structure in the derived category. These hearts are locally coherent Grothendieck categories and, in these categories, the pure-injective sheaves over the tubular curve become injective objects. In order to study injective objects in a Grothendieck category is fundamental the classification of the simple objects. In the seminar, we use some techniques coming from continued fractions and universal extensions to provide a method to construct an infinite dimensional sheaf of a prescribed irrational slope that becomes simple in the Grothendieck category given as the heart of a precise t-structure