Ce travail de doctorat explore les conséquences des activités de recherche d’emploi sur trois aspects de l’économie : la qualité des emplois à travers l’appariement entre les travailleurs et les entreprises, les contrastes géographiques en matière de chômage, et la croissance des salaires au cours de la vie. / This PhD dissertation explores the consequences of search activities on three dimensions of the economy: the quality of jobs through the matching between workers and firms, the geographical disparities in unemployment, and the wage growth over the life cycle through job mobility.

Les niveaux des taux de chômage des économies développés sont aujourd'hui sensiblement différents. Les institutions du marché du travail sont elles aussi diverses et protéiformes selon les pays. Ces institutions pourraient être considérées comme permettant d'accroître ou de réduire les niveaux de chômage. Or empiriquement, on ne trouve pas de lien direct et univoque entre les taux de chômage et les institutions sur le marché du travail. Si nous considérons plus précisément la façon dont les firmes décident de leur masse salariale, on réalise que l'on omet en faisant ce simple lien de corrélation, une variable essentielle qui détermine les comportements d'embauche et de licenciement des entreprises, à savoir la variable du financement. La capacité de financement externe des firmes pourrait déterminer, ou non, la demande de travail, conditionnellement aux institutions sur le marché du travail. Ainsi, le problème ne serait pas de savoir si les institutions sur le marché du travail conditionnent sa performance relative mais plutôt de savoir si le couple d'institutions sur le marché du travail et le marché du crédit détermine ces performances. Une entreprise est certes contrainte par la plus ou moindre grande flexibilité existante sur le marché du travail, mais ses calculs s'inscrivent dans une perspective plus large, qui est de savoir si elle a accès ou non aux financements dont elle a besoin. L'importance des frictions financières sur le marché du crédit détermine le niveau de la contrainte de financement externe pour les firmes. Cela pourrait alors avoir un impact sur leurs projets d'embauche et sur les niveaux d'emplois dans les économies. Les niveaux de frictions financières devraient donc influencer le niveau des principales variables macroéconomiques relatives au marché du travail, que sont le chômage, le niveau du salaire et le nombre de postes vacants, conditionnellement aux institutions existantes sur le marché du travail. / Unemployment rates in developed economies are now significantly different. Labor market institutions are also diverse and multifaceted. These institutions could be considered as allowing to increase or to reduce the levels of unemployment. However empirically, there is no direct and unambiguous link between unemployment rates and institutions in the labor market. By considering more precisely the way in which firms decide on their payroll, we realize that we omit, by making this simple correlation link, an essential variable that determines the hiring and firing behavior of firms, namely the funding variable. The external financing capacity of firms may determine the labor demand, conditional on the institutions in the labor market. Thus, the problem is not whether institutions in the labor market condition its relative performance but rather whether the couple of institutions in labor and credit markets determines this performance. A firm is certainly constrained by a greater or lesser flexibility in the labor market, but its computations are part of a broader perspective, which is whether or not it has access to the funding it needs. The importance of financial frictions in the credit market determines the level of the external financing constraint for firms. This could then have an impact on their hiring plans and job levels in economies depending on the prevailing labor market institutions. Financial frictions should therefore influence the main labor market macroeconomic variables, namely unemployment, wage level and the number of vacancies, conditional on existing labor market institutions.

Thesis advisor: Susanto Basu / This dissertation examines the fluctuations of the aggregate economy when frictions in financial markets are present. I focus on the the asymmetric information problems between creditors and debtors on the quality of debtor's projects and I analyze how these frictions cause the fluctuations in aggregate economy which is potentially inefficient. The first chapter examines the interaction between the perverse incentives and the general equilibrium effects of misallocated bank credit. This essay is intended to elucidate the mechanism of zombie lending in Japan. By incorporating a soft budget problem into a neo-classical dynamic general equilibrium model, the model shows that an inefficient zombie lending regime can be selected as an equilibrium. In this equilibrium, the incentives and the general equilibrium effects are interdependent. The inefficient use of resources crowds out investment when banks have incentives to bail out insolvent firms. On the other hand, the general equilibrium effects give rise to the perverse incentives endogenously through the formation of the liquidation value and the continuation value of insolvent firms. In the worst case, agents fail to resolve non-performing loan problems, and the model economy permanently falls into an inefficient regime. The second chapter proposes a model that generate boom-and-bust cycles by securitization of subprime mortgages. I construct a dynamic housing choice model in which mortgages are financed by securitization and I assume that creditors have errors in measuring the default risks of subprime mortgages. With this setup, the resource availability for housing fluctuates endogenously and it causes the boom-and-bust cycles. Particularly, there are two channels that change the resource availability: the security design of the securitized assets and the evolution of house price inflation. I illustrate that subprime mortgages can be cheaply financed by securitization when creditors mismeasure the quality of the subprime mortgages. This ignites a boom in the model. However, the boom can be terminated as the profitability of securitization declines along with the decline in the expectation of house price inflation. This is because the house price inflation is tied with the liquidation value of the defaulted mortgages. As the expectation of the house price inflation slows down, the subprime mortgages become more risky and the securitization becomes less profitable. Eventually, issuers of securitized assets withdraw from the securitization market and the boom collapses. The last chapter explores the transmission mechanisms of international business cycles when the borrowing capacity of multinational enterprises (MNEs) is limited. I embed MNEs that face borrowing constraints in a two-country international business cycle model. I show that the net worth of MNEs plays a significant role in generating the international business cycle co-movement: the wealth effect in response to the change in MNEs' net worth has a strong multiplier effect on domestic and foreign investment of MNEs. Output moves in the same direction between the two countries due to the synchronized investment. The model is also able to generate reasonable cross-country correlations in real estate price and consumption. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

I study optimal monetary and macroprudential policies in a New Keynesian DSGE framework with leverageconstrainedbanks. In particular, I assess the desirability of alternative operational policy rules when theeconomy is hit by mortgage default shocks and show that their implications for inflation dynamics and policytrade-offs depend on whether the shocks originate in the household sector or in the entrepreneurial sector ofthe economy. Moreover, I find that the strategy of ‘leaning against the wind’ (LAW) of credit growth deliverssystematically poorer stabilization outcomes than standard flexible inflation-targeting when there exists anon-trivial trade-off between stabilizing output and inflation, but outperforms conventional monetary policyfor shocks that generate a comovement between the two, irrespective of the real or financial nature of theshock.I show that optimal macroprudential regulation that is as concerned with output as monetary policy candrastically reduce, and in many cases completely eliminate, the incentive to lean against the wind. I arguethat this is due to the ability of full-fledged optimal macroprudential policy to break the favourable complementaritybetween stabilizing credit growth and stabilizing output growth which underlies the incentive tolean against the wind. Macroprudential policy proves a superior substitute to LAW because it can achieve thesame financial stability objectives without systematically imposing costs in terms of price stability.

This thesis consists of three theoretical chapters, all related to the response of unemployment to shocks and the role of active and passive labour market policies. Throughout the thesis, unemployment is assumed to evolve as a result of the uncoordinated nature of the labour market along the lines outlined in the Diamond-Mortensen-Pissarides equilibrium search and matching model. Chapter 2 examines the effects of employment policies on vacancy creation and allocation decisions of firms and unemployment across workers with different skills. We develop a partial equilibrium model with heterogeneous high- and low-tech jobs and with skilled and unskilled workers, which we motivate by the stark evidence on the incidence of cross-skill employment (which crowds out unskilled workers, e.g. evidence for the US, the UK and the EU put these at 58%, 32%, and 35%, respectively). We show that certain employment protection policies could, in fact, lead to a reduction in job creation and might alter the allocation of vacancies across low- and high-tech job type. We find that: (i) skilled workers benefit while unskilled workers experience high jobless rate; (ii) policy effects differ when they are skill-specific; (ii) stricter policies can have more severe consequences; and (iv) vacancy creation subsidy can play a key role in reducing unemployment across worker type as well as alleviating the cross-skill crowding out of jobs. Against conventional wisdom, we demonstrate that severance compensation can have a ‘real’ effect on job creation decision, provided there is some degree of strictness in its enforcement. Motivated by the extensive use of fiscal stimulus policies and labour market reforms during the last economic crisis, in Chapter 3 we study the implications of labour market regulations in driving the sensitivity of an economy to fiscal spending shocks, in a Dynamic Stochastic General Equilibrium (DSGE) model with job search frictions. We demonstrate that less rigidity in the labour market reduces the impact of fiscal demand shock on job creation and employment, both at extensive and intensive margins, whereas higher rigidity amplifies it. We also establish that the extent to which government spending promotes economic activity, job creation and employment depends on the degree of substitutability between private and public consumption. Higher substitutability dampens economic activity and reduces the sizes of output and employment multipliers. Labour market-oriented fiscal spending is found to be the most potent policy instruments for promoting employment – especially in the presence of high labour market rigidities. Finally, in Chapter 4, we study how openness to international trade and capital mobility and their interactions with labour market policies affect the behaviour of an economy, in particular with respect to its unemployment level. We show that the degree of openness to international capital flow is crucial for understanding the response of unemployment to different shocks. In isolation, by raising the incentive to invest, a reduction in capital mobility barriers leads to lower unemployment, both in the long-run and the dynamic short-run. With limited restrictions to capital movement, unemployment responds faster and with greater magnitude to a domestic productivity shock, and this is further enhanced the more the economy is open to international trade. A striking finding of this study is that while a higher degree of capital mobility enhances the adjustment of unemployment in response to a domestic productivity shock, it dampens its adjustment to a foreign demand shock. By contrast, higher openness to international trade enhances the adjustment effects of both shocks on unemployment. Finally, we find that heterogeneity in the welfare state systems in the EU can generate substantial differentials in the adjustment of unemployment to various shocks.

This dissertation presents three chapters addressing issues pertaining to monetary policy, information, and central bank communication. The first chapter studies optimal monetary policy in an environment where policy actions provide a signal of economic fundamentals to imperfectly informed agents. I derive the optimal discretionary policy in closed form and show that, in contrast to the perfect information case, the signaling channel leads the policymaker to be tougher on inflation. The strength of the signaling effect of policy depends on relative uncertainty levels. As the signaling effect strengthens, the optimal policy under discretion approaches that under commitment to a forward-looking linear rule, thereby decreasing the stabilization bias. This contributes to the central bank finding it optimal to withhold its additional information from private agents. Under a general linear policy rule, inflation and output forecasts can respond positively to a positive interest rate surprise when the signaling channel is strong. This positive response is the opposite of what standard perfect information New Keynesian models predict and it matches empirical patterns found by previous studies. Chapter 2 provides new empirical evidence supporting the predictions of the model presented in Chapter 1. More specifically, I find that the responses of inflation forecasts to interest rate surprises is especially positive when there is greater uncertainty regarding the previous forecast. Finally, Chapter 3 examines whether communications by the Federal Open Market Committee might have the ability to influence financial market responses to macroeconomic news. In particular, I am able to relate labor-related word use in FOMC statements and meeting minutes to the amount by which interest rates' response to labor-related news exceeds their response to other news. / Economics

This dissertation studies the impact of several different housing market features on the macroeconomy. Chapter 1 augments the New-Keynesian model with collateral constraints to incorporate long-term debt in order to examine the interaction between multi-period loans, leverage, and indeterminacy. Allowing firms to borrow heavily against commercial housing by increasing the loan-to-value ratio from 0.01 to 0.90 reduces the level of steady state output approximately 3.19% and decreases social welfare. In contrast, increasing the debt limit of households increases steady state output by 2.72%. Social welfare is maximized under a utilitiarian function when households can borrow at a loan-to-value ratio of about 0.49. An economy with long-term debt also makes stabilization much more difficult for monetary policymakers because determinacy is harder to attain. Instead of only having to satisfy the Taylor Principle (which implies that a more than one-to-one response to inflation), central bankers must either use a strict inflation target or aggressively respond to inflation and the output gap to ensure determinacy. Chapter 2 examine a New-Keynesian model with housing where default occurs if housing prices are sufficiently low, resulting in a loss of access to credit and housing markets. Default decreases aggregate and patient household consumption, increases impatient household consumption, and amplifies the decline in housing prices due to a misallocation of housing. The effects on consumption often peak immediately before default occurs. Policies that prevent underwater borrowing or raise interest rates along with housing prices are generally desirable because they increase utilitarian social welfare. This paper shows that default is not simply a symptom of economic downturns, but a cause. Chapter 3 explores the correlation between the home mortgage interest deduction (HMID) and state economic growth. The HMID was introduced to incentivize home purchases by distorting the after-tax price, resulting in an overinvestment in real estate. Previous empirical work has shown that investment in physical capital increases economic growth more so than investment in structures. Theoretically, the anticipated effect of the HMID would be lower subsequent economic growth. However, this paper finds that residential housing is actually beneficial for economic growth.

This thesis deals with the tribological and dynamic aspects of tactile perception given by the scanning of the finger on a surface. The attention is focused on a direct analysis of the vibration spectrum characteristics, induced by the surface features that is a relatively new research field. In fact, it is accepted that vibrations activate the tactile afferents and their essential role for the perception of fine textures (duplex theory of tactile texture perception) but it is still unknown the link with the surface texture characteristics and the features of the induced vibration spectra. The work is aimed to contribute to a better understanding of the mechanisms of the tactile sense, that is basilar for manifold different applications: textile quality quantification, ergonomics of everyday objects (which largely affects their commercial competitiveness), identification of surface imperfections, the design of tactile communication devices, the development of artificial tactile sensors for intelligent prostheses or robotic assistants, the development of human-machine interfaces for interaction with virtual realities or teleoperation systems, such as for telediagnosis or microsurgery, reproducing real perception (virtual reality), increasing the human perception (augmented reality), development of tests for evaluation of tactile sensitivity during diagnosis or monitoring process in rehabilitation. The study of a finger that moves on a surface involves different difficulties that are related to the material characteristics and to the measurements themselves. For these reasons, a new experimental set-up, named TriboTouch, has been developed to reproduce the finger/surface scanning phenomena under real values of the contact feature (scanning velocity and amplitude, surface roughness, etc..), avoiding undesired vibrations. The test bench has been designed to guarantee the measurements reproducibility and to perform measurements without introducing external noise. The set-up permits to carry out both measurements of the global dynamics and local ones (at the contact zone) employing a silicone fake finger. In the presented analysis, the behavior of the right hand index finger scanning on the surface sample with periodical and isotropic roughness and on textiles has been investigated for different scanning speed, highlighting the role of fingerprints A simple numerical model have been developed for reproducing the behavior of the induced vibrations when sliding two periodical surfaces and the numerical results have been compared with the experimental ones. The presented work has shown the possibility to obtain objective indexes for the tactile perception characterization, by means of the friction induced vibration spectrum analysis, in agreement with the neurophysiological studies present in literature.

Distortions that affect macroeconomic outcomes are an important avenue through which we can explain differences in cross country output and productivity. In this thesis I concentrate on two types of distortions, political economy and informational distortions. In Chapter one, I build a model of intermediated corruption where interactions between government bureaucrats and those who bribe them are mediated by a third party. I show that intermediation has significant effects on the incidence of corruption and the prices entrepreneurs pay for permits. When corruption is particularly acute, measures that increase the frequency with which government bureaucrats are audited often have the undesirable result of increasing the prevalence of corruption because of intermediation. In Chapter two I explore the link between corruption and inequality by building a model in which tax collectors are corrupt. I find that as inequality increases, the frequency of corrupt transactions increases as well. I also find that where corruption is more severe, because wealthier individuals tend to pay lower taxes, inequality is higher. I perform a few quantitative experiments to better understand this linkage. Chapter three explores distortions that are caused by adverse selection in markets with search frictions. I find that when participants are concerned about the information they reveal through their interactions in the market, the distortions to liquidity are deeper and that equilibrium selection is significantly affected. I also find that markets with reputational concerns are more sensitive to outside shocks.

Distortions that affect macroeconomic outcomes are an important avenue through which we can explain differences in cross country output and productivity. In this thesis I concentrate on two types of distortions, political economy and informational distortions. In Chapter one, I build a model of intermediated corruption where interactions between government bureaucrats and those who bribe them are mediated by a third party. I show that intermediation has significant effects on the incidence of corruption and the prices entrepreneurs pay for permits. When corruption is particularly acute, measures that increase the frequency with which government bureaucrats are audited often have the undesirable result of increasing the prevalence of corruption because of intermediation. In Chapter two I explore the link between corruption and inequality by building a model in which tax collectors are corrupt. I find that as inequality increases, the frequency of corrupt transactions increases as well. I also find that where corruption is more severe, because wealthier individuals tend to pay lower taxes, inequality is higher. I perform a few quantitative experiments to better understand this linkage. Chapter three explores distortions that are caused by adverse selection in markets with search frictions. I find that when participants are concerned about the information they reveal through their interactions in the market, the distortions to liquidity are deeper and that equilibrium selection is significantly affected. I also find that markets with reputational concerns are more sensitive to outside shocks.