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Nel primo articolo, stimiamo l'economia sommersa di 49 paesi dal 1981 al 2005. Il nostro studio si basa sull'utilizzo dei consumi elettrici filtrati per i cambiamenti tecnologici e le variazioni nella quota del settore industriale. Contrariamente agli studi basati sul metodo MIMIC, noi otteniamo una riduzione nella dimensione dell'economia sommersa. Contrariamente a La Porta and Shleifer (2008), inoltre, identifichiamo misure di qualità istituzionale che sono significativamente correlate all'economia sommersa, pur controllando per il PIL pro-capite. L'economia non registrata non può, dunque, essere considerata una conseguenza del sotto sviluppo. Al contrario, l’attività economica sommersa è relazionata a specifici aspetti istituzionali che possono sopravvivere con la crescita economica. Inoltre, identifichiamo un forte effetto sostituzione tra il settore ufficiale e quello non ufficiale. Questo risultato ha importanti implicazioni sia per la convergenza dei redditi che per la relazione tra volatilità e crescita. Nel secondo articolo, analizziamo il ruolo di istituzioni, crescita e politiche nel determinare l’economia sommersa. La forte separazione tra assunti teorici sulle determinanti istituzionali del sommerso e le tecniche di misurazione utilizzate rappresenta il primo aspetto innovativo del lavoro. Sfruttando, inoltre, la dimensione time-series del panel, siamo in grado di meglio analizzare il nesso tra crescita del PIL ufficiale e dimensione relativa del sommerso. Il terzo aspetto innovativo dell’articolo si riferisce al contributo apportato al lungo dibattito circa il ruolo di istituzioni e politiche nel determinare i risultati economici. In terzo articolo, rovesciamo l’approccio standard tipicamente seguito nella letteratura relativa all’economia sommersa. Invece di utilizzare i dati sulla domanda di moneta per ottenere stime sulla dinamica del sommerso, analizziamo gli effetti di lungo periodo dell’economia non registrata sulla velocità di circolazione della moneta. Il nostro contributo è duplice: i) apportiamo un miglioramento alla letteratura sulle determinanti della velocità di circolazione della moneta; ii) testiamo indirettamente la credibilità delle stime del sommerso presentate nel primo articolo della tesi. / In the first paper, we estimate the unrecorded economy in 49 economies from 1981 to 2005. Our study is based on electricity consumption series which are filtered to account for technological change and for the changing weight of the energy-intensive industrial sector. In contrast with studies based on the MIMIC method, we obtain a reduction in the weight of the unobserved economy. Unlike La Porta and Shleifer (2008), we identify measures of institutional quality which are significantly related to the shadow economy even after controlling for per-capita GDP. Thus the shadow economy should not be dismissed as the unpleasant side effect of underdevelopment. Instead it is related to some specific institutional aspects that may well survive even when the economy reaches higher development stages. We identify strong substitution effects between official and unofficial sectors both in the long run and over the business cycle. This has important implications for income convergence and for the relationship between volatility and growth. In the second paper, we investigate the distinct roles played by institutions, growth and policies in determining the shadow economy. The sharp distinction between theoretical priors on the institutional determinants of the shadow economy and the technique used for its measurement is the first novel contribution of the paper. The second innovation is that, by exploiting the time series dimension of our panel, we are able to better investigate the link between official output growth and the relative size of shadow economy. The third innovation is that we can contribute to a long-standing controversy about the distinct roles of "institutions" and "policies" in determining economic outcomes. In the third paper we reverse the standard approach typically followed in the literature on the shadow economy. Instead of exploiting money demand data to extrapolate the dynamics of the shadow economy, we explore the long run effect of shadow economy measures – obtained independently from money demand functions - on money velocity. By doing this, the original contribution of the paper is twofold. First, we improve the understanding of money velocity determinants. Second, we provide an indirect test of the reliability of the estimates on the shadow economy presented in the first paper of the thesis.

The purpose of this study is to examine the relationship between wealth, wealth inequality and health. The study has a cross-national focus and employs a political economy perspective, which addresses the macro-political determinants of health. The dissertation is comprised of two sets of analyses. In Part 1, logistic regression analyses confirm that wealth, whether measured as home ownership, the value of the home, or net worth, is a significant predictor of self-rated health in the United Kingdom, the United States, and Germany. The relationship between wealth and self-rated health is weakest in Germany. Case studies of the three countries indicate that this weaker relationship may be linked to more generous welfare state provisions in Germany. In Part 2, bivariate analyses reveal that wealth inequality, whether measured as the Gini coefficient or the share of wealth held by the richest 10% of the population, is related to poorer population health outcomes in developed countries. Both unweighted and weighted correlations are strong and significant, even after controlling for a variety of potential macro-level confounders. The results are strongest for female life expectancy and infant mortality. In-depth analysis of the countries with the most equitable distribution of wealth and the best health outcomes reveals several themes: high rates of home ownership, relatively generous pensions, stronger regulatory frameworks, taxation of wealth, increased social expenditures in recent years, and social cohesion. The results of this dissertation suggest that wealth is an axis of inequality that deserves far more attention from sociologists, particularly in relation to population health. Relying on income alone to describe inequality and form public policy is inadequate for understanding and addressing the economic and health circumstances of individuals and families. The inclusion of wealth in sociological studies of health disparities will result in a more accurate picture of social stratification, and will result in better informed social policy. Finally, the use of a political economy framework allows us to better understand, and potentially change, the political and economic processes through which the distribution of both wealth and health occurs.

This study discusses the performance and prospects of the Nigerian economy in the wake of the oil euphoria. It produces some empirical evidence for the rapid destruction of Nigerian agriculture in the past ten years or more and it demonstrates that the plight of the Nigerian economy in general and the rural sector in particular was in part a direct consequence of the increase in oil revenue which pushed up the exchange rate and made it unprofitable to grow crops for export. It concludes that unless a radical change in government policy is effected to revive the agricultural sector, Nigeria will experience a depletion of both her oil and her agricultural resources to the extent that the economy could eventually face a food crisis like those recently experienced in Ethiopia, Sudan, Mali or Chad, and without an industrial base. The study argues that contrary to the view commonly held in Nigeria, the benefits in the medium and long term of devaluing the Nigerian currency(naira) will greatly outweigh the costs which are likely to be only temporary. We use the term "Dutch disease", as it was in the Netherlands, that the phenomenon of the adverse effects on the rest of the economy of a rise in the exchange rate, brought about by the discovery of natural gas, was first observed.

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The work reported in this thesis was conducted to study the effects of variable valve actuation on combustion, emissions, and fuel economy in a modern design of 4-valve per cylinder SI engine. The use of statistically-based procedures for the design of experiments allowed a limited number of tests to be used to explore a wide region of each of the experimental variables. A series of steady-flow tests was conducted to assess the effects of valve lift on flow past the valves and the nature of any in-cylinder motion generated. Results from the former were incorporated into a filling and emptying model that allowed levels of trapped residuals and pumping work to be estimated for different valve strategies. The in-cylinder motion tests explored asymmetric valve lifts, that is to say where the two valves were opened by a different amount. These results allowed a pair of response surfaces to be established to model the intensity of both axial and barrel swirl within the cylinder over the range of valve lifts. Engine tests were conducted in two parts. The first explored the effects of changes in exhaust event phasing, intake event phasing, intake event duration, and peak intake valve lift. The design of the experiment allowed linear, quadratic, and interactions between the variables to be modelled using regression analysis. Statistical analysis allowed the most influential factors (both main effects and interactions) to be identified. Contour plots of the modelled response were used to draw conclusions about the nature of the response surface and to isolate the effects of valve opening and closure angles as well as overlap. The results were correlated with those from the steady-flow tests and from the computer model. The strategy for the second phase of tests was chosen after considering the previous results. The steady-flow tests indicated that there was considerable potential for enhancing in-cylinder motion by adopting a valve deactivation strategy and combining it with a low lift of the active intake valve. The second phase investigated the use of such a technique in conjunction with large overlaps over a range of duration of the intake valve event. The results from both phases of engine tests indicated possible strategies to reduce emissions from future engines.

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