Essays in Macroeconomics

The dissertation consists of four papers that aim at providing new contributions in the field of macroeconomics, monetary policy and financial stability. The first paper proposes a new Dynamic Stochastic General Equilibrium (DSGE) model with credit frictions and a banking sector to study the pro-cyclicality of credit and the role of different prudential regulatory frameworks in affecting business cycle fluctuations and in restoring macroeconomic and financial stability. The second paper develops a simple DSGE model capable of evaluating the effects of large purchases of treasuries by central banks. This theoretical framework is employed to evaluate the impact on yields and the macroeconomy of large purchases of medium- and long-term government bonds recently implemented in the US and UK. The third paper studies the effects of ECB communications about unconventional monetary policy operations on the perceived sovereign risk of Italy over the last five years. The empirical results are derived from both an event-study analysis and a GARCH model, which uses Italian long-term bond futures to disentangle expected from unexpected policy actions. The fourth paper proposes a DSGE model with an endogenous term structure of interest rates, which is able to replicate the stylized facts regarding the yield curve and the term premium in the US over the period 1987:3-2011:3, without compromising its ability to match macro dynamics.

A study on the macroeconomics of climate change

This work aims at exploring the relationship between business cycles, having frequencies rooted in the short run, and climatic phenomena, which span longer time horizons. The ultimate goal is to provide a theoretical framework to address these questions: How could very long run considerations affect short run economic decisions? How short run and transitory decisions could exert a long lasting effect on climate? This is achieved by means of an off-the-shelf real business cycle (RBC) model augmented so as to include a climatic block. The economy is perturbed by a technology shock and an energy-price shock. In general, the model performs relatively well in reproducing the cyclical characteristics of the economic variables; however, it is not as successful in capturing the cyclical behavior of climatic variables. Finally, it proposes a set of policy experiments, all taking the form of an energy tax directly or indirectly linked to the climatic status. As a matter of fact the effect of any tax responsive to the business cycle shows positive aspects: when a technology shock hits the economy, it mitigates global warming with minor costs in terms of potential output losses. It also protects the economy from an increase in energy prices, sustaining a certain level of output despite the fall in fossil energy use.

Essays in macroeconomics: insurance, market power, and inequality

This thesis investigates a broad range of topics related to insurance, market power, and inequality, both from an empirical and a theoretical perspective. In the first chapter, I exploit the significant heterogeneity of the shocks hitting Ethiopian households and their heterogeneous response, using relatively recent data (World Bank's LSMS-ISA for households and satellite data for weather shocks). On the one hand, households seem able to insure against most idiosyncratic and mild adverse weather shocks. On the other hand, vulnerability to stronger weather shocks (especially droughts) remains elevated. In the second chapter, starting from firms' individual data, aggregate trends about industry concentration and other proxies of competition are built. This chapter is part of a larger project conducted at the OECD in the Productivity Innovation and Entrepreneurship Division of the STI Directorate The project innovates on the existing literature in its measurement of concentration, aimed at reflecting markets more accurately. On average, aggregate concentration is found to be increasing. In the third chapter, which only lays out some preliminary steps of a more extensive inquiry, I model the heterogeneous effects of aggregate technological progress on individual economic agents and show how this can affect aggregate inequality and other aggregate indicators studied in the macroeconomics literature, such as the entrepreneurship rate and the overall firm distribution. It should be noted, however, that this note is a simple exposition of a possible modelling device rather than a full explanation of these phenomena.

La questione percettiva in semiotica. Linee fondamentali e sviluppi della ricerca

This dissertation deals with the problems and the opportunities of a semiotic approach to perception. Is perception, seen as the ability to detect and articulate an coherent picture of the surrounding environment, describable in semiotic terms? Is it possibile, for a discipline wary of any attempt to reduce semiotic meaning to a psychological and naturalized issue, to come to terms with the cognitive, automatic and genetically hard-wired specifics of our perceptive systems? In order to deal with perceptive signs, is it necessary to modify basic assumptions in semiotics, or can we simply extend the range of our conceptual instruments and definitions? And what if perception is a wholly different semiotic machinery, to be considered as sui generis, but nonetheless interesting for a general theory of semiotics? By exposing the major ideas put forward by the main thinkers in the semiotic field, Mattia de Bernardis gives a comprehensive picture of the theoretical situation, adding to the classical dichotomy between structuralist and interpretative semiotics another distinction, that between homogeneist and etherogeneist theories of perception. Homogeneist semioticians see perception as one of many semiotic means of sign production, totally similar to the other ones, while heterogeneist semioticians consider perceptive meaning as essentially different from normal semiotic meaning, so much so that it requires new methods and ideas to be analyzed. The main example of etherogeneist approach to perception in semiotic literature, Umberto Eco’s “primary semiosis” is then presented, critically examined and eventually rejected and the homogeneist stance is affirmed as the most promising path towards a semiotic theory of perception.

La comunicazione della cooperazione allo sviluppo: gli Enti Pubblici. Analisi discorsive dei Siti Web

Our research takes place in the context of a discipline kwown as Communication for Development, sited inside the field of Communication for Social Change, characterized by the use of interpersonal ad mass communication theories and tools, applyied to international development cooperation. Our study aims at pointing out a change of paradigm in this field: our object is Public Administration’s communication, therefore, what we suggest is a shift from Communication for Development, to Development Communication. The object of our study, hence, becomes the discourse itself, in its double action of representation and construction of reality. In particular, we are interested in the discourse’s tribute to the creation of a collective immagination, wich is the perspective towards which we have oriented the analysis, through a structuralist semoitics-based methodology integrated with a socio-semiotic approach. Taking into consideartion the fact that in our contemporary society (that is to say a ‘Western’ and ‘First World’ society), the internet is a crucial public space for the mediation and the management of collective immagination, we chose the web sites of Public Bodies which are dedicated to International Cooperation has our analysis corpus. This, due to their symbolic and ideologic significance, as well as for the actual political responsibility we think these web sites should have. The result of our analysis allows us to suggest some discoursive strategies used in the web sites of Public Bodies. In these sites, there is a tendency to shift the discourses around international cooperation from the ideological axis - avoiding in so doing to explicit a political statement about the causes of injustices and un-balances which lead to the necessity of a support in development (i.e. avoiding to mention values such as social justice and democracy while acknowledging socio-economical institutions which contribute to foster underdevelopment on a global scale) -, to the ethical axis, hence referring to moral values concerning the private sphere (human solidarity and charity), which is delegated mainly to non governamental associations.

Sostanzialismo e relazionalismo dello spaziotempo alla luce della relatività generale

Until recently the debate on the ontology of spacetime had only a philosophical significance, since, from a physical point of view, General Relativity has been made "immune" to the consequences of the "Hole Argument" simply by reducing the subject to the assertion that solutions of Einstein equations which are mathematically different and related by an active diffeomorfism are physically equivalent. From a technical point of view, the natural reading of the consequences of the "Hole Argument” has always been to go further and say that the mathematical representation of spacetime in General Relativity inevitably contains a “superfluous structure” brought to light by the gauge freedom of the theory. This position of apparent split between the philosophical outcome and the physical one has been corrected thanks to a meticulous and complicated formal analysis of the theory in a fundamental and recent (2006) work by Luca Lusanna and Massimo Pauri entitled “Explaining Leibniz equivalence as difference of non-inertial appearances: dis-solution of the Hole Argument and physical individuation of point-events”. The main result of this article is that of having shown how, from a physical point of view, point-events of Einstein empty spacetime, in a particular class of models considered by them, are literally identifiable with the autonomous degrees of freedom of the gravitational field (the Dirac observables, DO). In the light of philosophical considerations based on realism assumptions of the theories and entities, the two authors then conclude by saying that spacetime point-events have a degree of "weak objectivity", since they, depending on a NIF (non-inertial frame), unlike the points of the homogeneous newtonian space, are plunged in a rich and complex non-local holistic structure provided by the “ontic part” of the metric field. Therefore according to the complex structure of spacetime that General Relativity highlights and within the declared limits of a methodology based on a Galilean scientific representation, we can certainly assert that spacetime has got "elements of reality", but the inevitably relational elements that are in the physical detection of point-events in the vacuum of matter (highlighted by the “ontic part” of the metric field, the DO) are closely dependent on the choice of the global spatiotemporal laboratory where the dynamics is expressed (NIF). According to the two authors, a peculiar kind of structuralism takes shape: the point structuralism, with common features both of the absolutist and substantival tradition and of the relationalist one. The intention of this thesis is that of proposing a method of approaching the problem that is, at least at the beginning, independent from the previous ones, that is to propose an approach based on the possibility of describing the gravitational field at three distinct levels. In other words, keeping the results achieved by the work of Lusanna and Pauri in mind and following their underlying philosophical assumptions, we intend to partially converge to their structuralist approach, but starting from what we believe is the "foundational peculiarity" of General Relativity, which is that characteristic inherent in the elements that constitute its formal structure: its essentially geometric nature as a theory considered regardless of the empirical necessity of the measure theory. Observing the theory of General Relativity from this perspective, we can find a "triple modality" for describing the gravitational field that is essentially based on a geometric interpretation of the spacetime structure. The gravitational field is now "visible" no longer in terms of its autonomous degrees of freedom (the DO), which, in fact, do not have a tensorial and, therefore, nor geometric nature, but it is analyzable through three levels: a first one, called the potential level (which the theory identifies with the components of the metric tensor), a second one, known as the connections level (which in the theory determine the forces acting on the mass and, as such, offer a level of description related to the one that the newtonian gravitation provides in terms of components of the gravitational field) and, finally, a third level, that of the Riemann tensor, which is peculiar to General Relativity only. Focusing from the beginning on what is called the "third level" seems to present immediately a first advantage: to lead directly to a description of spacetime properties in terms of gauge-invariant quantites, which allows to "short circuit" the long path that, in the treatises analyzed, leads to identify the "ontic part” of the metric field. It is then shown how to this last level it is possible to establish a “primitive level of objectivity” of spacetime in terms of the effects that matter exercises in extended domains of spacetime geometrical structure; these effects are described by invariants of the Riemann tensor, in particular of its irreducible part: the Weyl tensor. The convergence towards the affirmation by Lusanna and Pauri that the existence of a holistic, non-local and relational structure from which the properties quantitatively identified of point-events depend (in addition to their own intrinsic detection), even if it is obtained from different considerations, is realized, in our opinion, in the assignment of a crucial role to the degree of curvature of spacetime that is defined by the Weyl tensor even in the case of empty spacetimes (as in the analysis conducted by Lusanna and Pauri). In the end, matter, regarded as the physical counterpart of spacetime curvature, whose expression is the Weyl tensor, changes the value of this tensor even in spacetimes without matter. In this way, going back to the approach of Lusanna and Pauri, it affects the DOs evolution and, consequently, the physical identification of point-events (as our authors claim). In conclusion, we think that it is possible to see the holistic, relational, and non-local structure of spacetime also through the "behavior" of the Weyl tensor in terms of the Riemann tensor. This "behavior" that leads to geometrical effects of curvature is characterized from the beginning by the fact that it concerns extensive domains of the manifold (although it should be pointed out that the values of the Weyl tensor change from point to point) by virtue of the fact that the action of matter elsewhere indefinitely acts. Finally, we think that the characteristic relationality of spacetime structure should be identified in this "primitive level of organization" of spacetime.

Negoziare confini: dagli stati di cose ai transiti

Negotiating boundaries: from state of affairs to matter of transit. The research deals with the everyday management of spatial uncertainty, starting with the wider historical question of terrains vagues (a French term for wastelands, dismantled areas and peripheral city voids, or interstitial spaces) and focusing later on a particular case study. The choice intended to privilege a small place (a mouth of a lagoon which crosses a beach), with ordinary features, instead of the esthetical “vague terrains”, often witnessed through artistic media or architectural reflections. This place offered the chance to explore a particular dimension of indeterminacy, mostly related with a certain kind of phenomenal instability of its limits, the hybrid character of its cultural status (neither natural, nor artificial) and its crossover position as a transitional space, between different tendencies and activities. The first theoretical part of the research develops a semiotic of vagueness, by taking under exam the structuralist idea of relation, in order to approach an interpretive notion of continuity and indeterminacy. This exploration highlights the key feature of actantial network distribution, which provides a bridge with the second methodological parts, dedicated to a “tuning” of the tools for the analysis. This section establishes a dialogue with current social sciences (like Actor-Network Theory, Situated action and Distributed Cognition), in order to define some observational methods for the documentation of social practices, which could be comprised in a semiotic ethnography framework. The last part, finally, focuses on the mediation and negotiation by which human actors are interacting with the varying conditions of the chosen environment, looking at people’s movements through space, their embodied dealings with the boundaries and the use of spatial artefacts as framing infrastructure of the site.

La resistenza dei legami. Narrazioni e rappresentazioni della famiglia nella trilogia di romanzi “Past Imperfect” (2004-2011) di Nuruddin Farah

Il presente progetto di ricerca riguarda la terza trilogia di romanzi di Nuruddin Farah, “Past Imperfect” (2004-2011). L’analisi dei tre testi che compongono la trilogia – “Links” (2004), “Knots” (2007) e “Crossbones” (2011) – evidenzia la persistente rilevanza delle narrazioni e delle rappresentazioni della famiglia all’interno di tutta la produzione letteraria dell’autore. Questa prospettiva critica richiede l’impiego di una metodologia che riunisce vari aspetti della critica letteraria di matrice post-strutturalista e, per altri versi, di stampo materialista, assecondando così le due principali tendenze critiche presenti all’interno degli studi postcoloniali. Lo stesso approccio teorico-metodologico può essere applicato anche in altri due ambiti critici chiamati in causa dalla trilogia di Nuruddin Farah: la cosiddetta “world literature” e la cosiddetta “failed-state fiction”. L’analisi delle narrazioni e delle rappresentazioni della famiglia richiede, inoltre, un approccio interdisciplinare molto esteso, stimolando ricerche negli ambiti della semiotica, dell’antropologia, della psicanalisi, dei Gender Studies e dei Trauma Studies.