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Nanostructured materials for hydrophobic drug delivery
Full text linkPorous silicon (Psi) and nanocellulose (NC) hydrogels are nanostructured materials with several properties that make them promising for drug delivery applications. In this work, β-carotene (BC) and clofazimine (CFZ) are used as model molecules to investigate the physical and chemical processes governing the interactions of hydrophobic molecules with both inorganic (Psi) and organic (NC) nanostructured carriers. Despite the large number of advantages, Psi does not perform well as carrier for BC, since it stimulates the molecule degradation even if its surface is carefully passivated. Furthermore, during the release experiments, BC tends to nucleate on Psi surface forming aggregates whose dissolution is much slower than the BC molecules release, thus they negatively impact on the control over the drug release. On the other hand NC hydrogels do not pose heavy issues to the release of lipophilic drugs, provided that a suitable surfactant (either Tween-20 or Tween-80) mediates the molecule solvation and its subsequent release into aqueous media. Moreover, NC gels protect BC from degradation much better than its storage in freezer or in organic solvent, making these carriers interesting for DD
On the provenance of digital images
Full text linkDigital images are becoming the most commonly used multimedia data nowadays thanks to the massive manufacturing of cheap acquisition devices coupled with the unprecedented popularity of Online Social Networks. As two sides of a coin, massive use of digital images triggers the development of user-friendly editing tools and intelligent techniques that violate image authenticity. By this respect, digital images are less and less trustable as they are easily modified not only by experts or researchers, but also by unexperienced users. It has been also witnessed that malicious use of images has tremendous impact on human perception as well as system reliability. Those concerns highlight the importance to verify image authenticity.
In practice, digital images are created, manipulated, and diffused world-wide via many channels. Simply answering to the question "Is an image authentic?'' appears insufficient. Further steps aiming at understanding the provenance of images with respect to acquisition device or distributed platforms as well as the processing history have to be considered significant.
This doctoral study contributes solutions to recover digital image provenance under multiple aspects: i) image acquisition device, ii) social network origin, and iii) source-target disambiguation in image copy-move forgery
South-South Trade, Export Sophistication, and Terms of Trade: Empirical Studies on Developing Countries from 1995 to 2014
Full text linkIndustrialisation and trade are two major contributors to growth and development. Historical experience has clearly demonstrated the importance of industrialisation and manufactured exports in the transformation from a backward country to an advanced country. Moreover, industrialisation is not only an efficient way to increase productivity and welfare, but also an effective way to promote social and cultural changes. Over the recent decades, two trends in developing countries' industrialisation and trade have been well documented in the literature. First, manufactures have taken increasingly important share in many developing countries' export basket. Second, the fast-growing trade between developing countries, say, South-South trade, has been highlighted. Given the importance of industrialisation and trade in development process, this PhD thesis aims at contributing to knowledge on the evidence, mechanism, and determinants of developing countries' trade and industrialisation, centring on South-South trade, export upgrading, export directionality, and terms of trade over the recent two decades from 1995 to 2014. Each of the four topics is addressed in one of the following four chapters from Chapter 2 to Chapter 5.
Chapter 2 criticises the existing approach towards the definition of the Global South and South-South trade, and clarifies that the delightful picture of South-South trade highlighted in the literature is actually an "illusion". Including de facto developed countries (e.g., the Asian Tigers) and emerging countries in the group of developing countries strongly inflates the size and growth of South-South trade. If these countries are excluded, then the relative size of South-South trade becomes quite small. In particular, this chapter demonstrates that including these de facto developed and emerging countries in South-South trade statistics heavily overstates technological and manufacturing capabilities of the so-called "Global South". Moreover, this chapter also explores the composition of developing countries' exports to different trade partners and their trade potential with the rest of the world. It reveals great differences in the composition between developing countries' different export directions and significant asymmetries in mutual trade potential between developing countries and the rest of the world.
Chapter 3 examines the determinants of developing countries' export upgrading with a particular interest in the role of China and productive investment. Amongst general factors, access to sea, human capital, productive investment, and trade openness are found to be major contributors to developing countries' export upgrading. The robust effect of productive investment reflects the importance of political and social agents' motivations of industrialisation and, perhaps more importantly, endemic political-economic embeddedness that determines the motivations. This echoes the centrality of strong and developmentally-oriented elites in the developmentalist model of industrialisation and development. Developing countries' absolute gains from trade with China, as reflected by the significant improvement in their income terms of trade vis-à-vis China, promote their export upgrading. Importantly, mediation analysis shows that this export-upgrading effect operates, to a large extent, through the enhancing effect of trade with China on developing countries' productive investment. This export-upgrading effect of absolute gains from trade with China is stronger and more robust in the period of 2002-2014 than 1995-2014, which is consistent with the growing role of China in the global economy since the early 2000s, reflecting on China's commodity boom and its strong performance in manufactured exports. That is to say, trade with China serves as a source of investment for developing countries' export upgrading. This finding provides a new and indirect channel to understand the influence of China on developing countries' industrialisation, going beyond the conventional perspectives of the "crowding-out" effect and the "re-primarisation" effect. It suggests that, for developing countries, China serves more as a stimulator of capital accumulation than a competitor in manufacturing market or a predator of natural resources. Therefore, the priority for developing countries is the appropriate use of gains from trade for productive purpose.
Chapter 4 provides the latest evidence to the discussion in the 1980s on developing countries' export directionality, and explores the determinants of this directionality. Between 1995 and 2014, more than half of developing countries tended to have more sophisticated Southbound exports than Northbound exports, while the opposite is true for the rest. Productive capabilities are found to be a major and robust determinant of this directionality of export sophistication. Productively more advanced developing countries are more likely to have more sophisticated Northbound exports than Southbound exports, which is likely to be due to their ability to access the more competitive markets of developed and emerging countries and/or the downstream value chains with their relatively sophisticated products. In contrast, productively less advanced developing countries have to access developed and emerging countries' markets and/or the downstream value chains with their less sophisticated products, due to the lack of competitiveness in more sophisticated products. This finding suggests that the conventional argument that South-South trade is more beneficial to developing countries than North-South trade should be interpreted conditionally, because, for those productively more advanced developing countries, Northbound exports are likely to be more sophisticated. Another important contributor to the directionality of export sophistication is geographical distance. Larger distance to other developing countries reduces a developing country's Southbound export sophistication or increases its Northbound export sophistication, which is consistent with the argument of the gravity model in a broad sense.
Chapter 5 examines the recent trends of developing countries' terms of trade under the trichotomous global economic hierarchy consisting of developed, emerging, and developing countries. Time-series analysis shows that developing countries, especially those specialising in fuels or minerals, have experienced an improvement in their net barter terms of trade vis-à-vis developed countries over the recent two decades. In contrast, developing countries' net barter terms of trade vis-à-vis China and other emerging countries tends to show negative or trendless behaviour, except those specialising in mineral fuels. In summary, on a global scale, developing countries specialising in fuels or minerals have tended to hold a favourable position, whereas those specialising in agricultural products or manufactures have experienced a less favourable or even unfavourable situation. On the other hand, income terms of trade of all groups of developing countries vis-à-vis the rest of the world, regardless of developed countries, China or other emerging countries, has significantly improved. This indicates developing countries' absolute gains from trade with the rest of the world. However, the rest of the world has comparable improvement in their income terms of trade vis-à-vis developing countries. Therefore, despite the favourable income terms of trade facing developing countries, the condition for global (North-South) convergence does not hold. As a consequence, developing countries have to mobilise more resources to maintain the favourable income terms of trade, which impedes their domestic consumption and investment, and the unequal global exchange has remained. Particularly, this global inequality is magnified by the persistent North-South gap in productivity and technology and by developing countries' high population growth. The global inequality is rooted in the competitive nature of the markets for primary commodities and simple manufactures and the oligopolistic nature of the markets for sophisticated manufactures. In this sense, the findings are in line with the Prebisch-Singer hypothesis
Modelling and simulation in tribology of complex interfaces
Full text linkTribology is known as the science of surfaces in relative motion and involves complex interactions over multiple length and time scales. Therefore, friction, lubrication and wear of materials are intrinsically highly multiphysics and multiscale phenomena. Several modelling and simulation tools have been developed in the last decades, always requiring a trade-off between the available computational power and the accurate replication of the experimental results. Despite nowadays it is possible to model with extreme precision elastic problems at various scales, further eorts are needed for taking into account phenomena like plasticity, adhesion, wear, third-body friction and boundary and solid lubrication. The situation becomes even more challenging
if considering non-conventional nano-, as in the case of polymer surfaces and interfaces, or microstructures, as for the hierarchical organisations observed in biological systems. Specically, biological surface structures have been demonstrated to present exceptional tribological properties, for instance in terms of adhesion (e.g., the gecko pad), superhydrophobicity (e.g., the lotus leaf) or fluid-dynamic drag reduction (e.g., the shark skin). This has suggested the study and development of hierarchical and/or bio-inspired structures for applications in tribology.
Therefore, by taking inspiration from Nature, we investigate the effect of property gradients on the frictional behaviour of sliding interfaces, considering lateral variations in surface and bulk properties. 3D finite-element simulations are compared with a 2D spring-block model to show how lateral gradients can be used to tune the macroscopic coefficients of friction and control the propagation of detachment fronts. Complex microscale phenomena govern the macroscopic behaviour also of lubricated contacts. An example is represented by solid lubrication or third-body friction, which we study with 3D discreteelement
simulations. We show the effects of surface waviness
and of the modelling parameters on the macroscopic coefficient of friction. Many other natural systems present complex interfacial interactions and tribological behaviour. Plant roots, for instance, display optimised performance during the frictional penetration of soil, especially thanks to a particular apex morphology. Starting from experimental investigations of different probe geometries, we employ the discrete-element method to compute the expended work during the penetration of a granular packing, conrming the optimal bio-inspired shape. This has allowed to follow also an integrated approach including image acquisition and processing of the actual geometries, 3D printing, experiments and numerical simulations. Finally, another interesting example of advanced biological interface
with optimised behaviour is represented by biosensing strucviii tures. We employ fluid-structure interaction numerical simulations for studying the response of spiders' trichobothria, which are among the most sensitive biosensors in Nature. Our results highlight the role of the fluid-dynamic drag on the system performance and allow to determine the optimal hair density observed experimentally.
Both the third-body problem and the possibility to tune the frictional properties can be considered as the next grand challenges in tribology, which is going to live a "golden age" in the coming years. We believe the results discussed in this Doctoral Thesis could pave the way towards the design of novel bio-inspired structures with optimal tribological properties, for the future development
of smart materials and innovative solutions for sliding
interfaces
Numerical and experimental methods for seismic risk assessment of civil and industrial structures
Full text linkDue 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
Network Representation Learning with Attributes and Heterogeneity
Full text linkNetwork Representation Learning (NRL) aims at learning a low-dimensional latent representation of nodes in a graph while preserving the graph information. The learned representation enables to easily and efficiently perform various machine learning tasks. Graphs are often associated with diverse and rich information such as attributes that play an important role in the formation of the network. Thus, it is imperative to exploit this information to complement the structure information and learn a better representation. This requires designing effective models which jointly leverage structure and attribute information. In case of a heterogeneous network, NRL methods should preserve the different relation types.
Towards this goal, this thesis proposes two models to learn a representation of attributed graphs and one model for learning representation in a heterogeneous network. In general, our approach is based on appropriately modeling the relation between graphs and attributes on one hand, between heterogeneous nodes on the other, executing a large collection of random walks over such graphs, and then applying off-the-shelf learning techniques to the data obtained from the walks.
All our contributions are evaluated against a large number of state-of-the-art algorithms, on several well-known datasets, obtaining better results
Transatlantic trade partnerships and their consequences on copyright law: from global to regional
Full text linkProtection and enforcement of intellectual property law are fundamental to stimulate innovation and to compete in the global economy. Copyright law is not very involved in trade agreements, in which there is more space about other intellectual property rights, such as patents, geographical indications, protected designation of origin, trademarks, designs. By setting harmonized standards in copyright law, contracting States aim at reducing national discrepancies, ensuring the level of protection required to creativity and investments in production of new original works, promoting access to knowledge for users and business. The general purpose of harmonization through the negotiation of free trade agreements, among others in different fields, would be to enforce works protected by copyright law. It implies the necessary balance between the interests of right holders (in order to achieve a reinforced protection, including by extending the copyright term of protection) and users (by accessing copyright-protected works entered the public domain following the expiration of the term of protection). This equilibrium cannot be achieved by providing for an excessive extension of the term of protection of copyright, which risks distorting the copyright nature.
This research project concerns the rules provided in current trade negotiations about copyright law. Since the secrecy and lack of transparency of the trade negotiations, it has been difficult to reconstruct a precise path and background of specific language and wording of their provided rules. The reconstruction has possible thanks to leaked drafts and public statements. The result is that there are not many books and academic papers about this topic, by isolating it in academic studies
The effects of counterfactual comparison on learning and reasoning
Full text linkHow humans make choices in uncertain and competitive situations is a key determinant of viability and successful living. Improving those choices requires sometimes encountering undesirable outcomes and avoiding them, eventually even anticipating them in novel situations. Learning depends on making choices, encountering errors and updating evaluations of options. Various models extended from the reinforcement learning framework compared to human behavior describe in part how individuals heterogeneously make choices. To peer into the components of these mechanisms, strategic games that emulate real-world situations provide measurable and manageable environments in which to examine slight differences in choice behavior among different people. Such differences may be endogenous to participants (e.g. age or learning disposition) while others derive from external events (e.g. emotional induction or brain stimulation). We contrasted such behavior in three situations involving learning or competition, leveraging differences in age, emotional induction and brain stimulation. We aimed to describe the variations in choice behavior across these differences and investigated, when possible, how prior conditions generated a transfer of learning from one domain to another. The work here builds on recent investigations of neural mechanisms underlying choice behavior during strategic or competitive interaction
Three Economic Extensions of John Rawls's Social Contract Theory: European Fiscal Union, Tax Compliance and Climate Change
Full text linkIn my thesis I apply the ethical model developed by John Rawls (1999) to three systems which have an economic dimension: European Union, tax compliance and environmental sustainability. With this task my purpose is to answer to the following overarching research question: is an impartial and non-binding agreement, conceived in a Rawlsian frame, sufficient to generate fair and stable redistributive institutions? This general research question is then addressed and inflected according to the specific economic domains mentioned above
Effect of caregiving behaviors and genetic predispositions on human and non-human primates development
Full text linkParental sensitivity towards infants’ needs influences both the way caregiver-infant interactions unfold and individuals’ own development throughout lifetime. The pivotal role of this early interaction with caregivers is especially highlighted by the fact that when the interaction is non-adaptive, infants’ development may be severely hindered in various domains, such as cognitive, social, and emotional. Moreover, the quality of the early interaction with caregivers has long-lasting effects since it constitutes a lens through which individuals interpret the social world throughout lifetime. Caregivers’ influence on individuals’ subsequent behavior is also moderated by their own genetic predispositions. However the way behavioral, physiological and genetic mechanisms dynamically interact over time in shaping the development of caregiver-infant bonding and the long term effects on individuals remains largely unknown. The present project aimed to investigate behavioral and physiological mechanisms underling caregiver-infant interactions and their long-term effects applying a multilevel approach including behavioral, physiological and genetic measurements as well as a comparative approach between human and non-human primates. Specifically, in a first study focused on human adults we investigated the effect of the interaction between early parental care and individuals' own genetic predispositions in moderating adults' subsequent peripheral physiological responses to distressing social stimuli. Next, a second study on a primate model, the marmosets (\textit{Callithrix Jacchus}), focused directly on caregiver-infant dyads applying micro-behavioral analysis during infants' first month of life. Overall findings highlighted a differential importance of environmental and genetic factors in moderating caregiver-infant dyads vs individuals' long-term development. The leading role of environmental factors, namely parental behaviors, in determining infants' responses to specific caregivers within caregiver-infant interactions seems to be, on the contrary, smoothed out by individuals' own genetic predispositions when focusing on the long-term effects. Indeed, genetic characteristics determine individuals' sensitivity to environment, either weakening or strengthening the effect of environmental contribution in shaping individuals' physiological mechanisms. Also, interesting similarities between marmosets’ and humans’ caregiver-infant interactions’ structure have been found, making way for future studies investigating the brain mechanisms underlying the development of parent-infant bonding