Self-control and savings

We reconsider the well-established paradigm of a rational individual's choice of a consumption schedule, building on the idea that human beings devote resources to withstand their desire for immediate consumption, i.e. to become more patient, thereby making less remote the pleasure derived from deferred consumption. We construct an infinite-horizon model of a small open economy, in which individuals can accumulate a stock of personal capital that reduces the discount on future consumption. Personal capital captures the effect of a conumer's past experience and choices on his future utilities. Our main results are: i) when individuals are heterogenous with respect to ability to become patient all individuals exhibit the same rate of time preference in the long run; ii) effort is rewarded in the long run to the extent that individuals who need to make more effort to become patient are wealthier and enjoy a higher level of utility bin the steady state. The latter result stems from the complementarity between personal capital and deferred consumption. JEL Classification: E13

Intergenerational altruism and neoclassical growth models

This paper surveys intergenerational altruism in neoclassical growth models. It first examines Barro's approach to intergenerational altruism, whereby successive generations are linked by recursive altruistic preferences. Individuals have an altruistic concern only for their children, who in turn also have altruistic feelings for their own children. The conditions under which the Ricardian equivalence (debt neutrality) theorem applies are specified. The effectiveness of fiscal policy is further analysed in the context of an economy populated by heterogeneous families differing with respect to their degree of intergenerational altruism. Other forms of altruism, referred to as ad hoc altruism, are also examined, along with their implications for fiscal policy. JEL Classification: E13, D64, E62, C60altruism, fiscal policy, Neoclassical general aggregative models

Public pensions and growth

This paper investigates the relationship between the size of an unfunded public pension system and economic growth in an overlapping generation economy, in which altruistic parents finance the education of their children and leave bequests. Unlike the existing literature, we model intergenerational altruism by assuming that children's income during adulthood is an argument of parental utility. Unfunded public pensions can promote growth when families face liquidity constraints preventing them from investing optimally in the education of their children. We consider two alternative ways of financing a public pension system, either by levying social contributions in a lump-sum manner or in proportion to labour income. We find that there is no case for unfunded public pensions in economies where bequests are operative. By contrast, there exists a growth-maximising size of the public pension system in economies where bequests are not operative and individuals are sufficiently patient JEL Classification: H55, I20, D91Education, Growth, Public pension

Debt stabilizing fiscal rules

Unstable government debt dynamics can typically be corrected by various fiscal instruments, like appropriate adjustments in government spending, public transfers, or taxes. This paper investigates properties of state-contingent debt targeting rules which link stabilizing budgetary adjustments around a target level of long-run debt to the state of the economy. The paper establishes that the size of steady-state debt is a key determinant of whether it is possible to find a rule of this type which can be implemented under all available fiscal instruments. Specifically, considering linear feedback rules, the paper demonstrates that there may well exist a critical level of debt beyond which this is no longer possible. From an applied perspective, this finding is of particular relevance in the context of a monetary union with decentralized fiscal policies. Depending on the level of long-run debt, there might be a conflict between a common fiscal framework which tracks deficit developments as a function of the state of the economy and the unrestricted choice of fiscal policy instruments at the national level. JEL Classification: E63, H62fiscal regimes, overlapping generations

Debt stabilizing fiscal rules

Unstable government debt dynamics can typically be corrected by various fiscal instruments, like appropriate adjustments in government spending, public transfers, or taxes. This paper investigates properties of state-contingent debt targeting rules which link stabilizing budgetary adjustments around a target level of long-run debt to the state of the economy. The paper establishes that the size of steady-state debt is a key determinant of whether it is possible to find a rule of this type which can be implemented under all available fiscal instruments. Specifically, considering linear feedback rules, the paper demonstrates that there may well exist a critical level of debt beyond which this is no longer possible. From an applied perspective, this finding is of particular relevance in the context of a monetary union with decentralized fiscal policies. Depending on the level of long-run debt, there might be a conflict between a common fiscal framework which tracks deficit developments as a function of the state of the economy and the unrestricted choice of fiscal policy instruments at the national levelFiscal regimes, overlapping generations

Self-control and savings

We reconsider the well-established paradigm of a rational individual's choice of a consumption schedule, building on the idea that human beings devote resources to withstand their desire for immediate consumption, i.e. to become more patient, thereby making less remote the pleasure derived from deferred consumption. We construct an infinite-horizon model of a small open economy, in which individuals can accumulate a stock of personal capital that reduces the discount on future consumption. Personal capital captures the effect of a conumer's past experience and choices on his future utilities. Our main results are: i) when individuals are heterogenous with respect to ability to become patient all individuals exhibit the same rate of time preference in the long run; ii) effort is rewarded in the long run to the extent that individuals who need to make more effort to become patient are wealthier and enjoy a higher level of utility bin the steady state. The latter result stems from the complementarity between personal capital and deferred consumption

Direct Evidence for Two Different Neural Mechanisms for Reading Familiar and Unfamiliar Words: An Intra-Cerebral EEG Study

After intensive practice, unfamiliar letter strings become familiar words and reading speed increases strikingly from a slow processing to a fast and with more global recognition of words. While this effect has been well documented at the behavioral level, its neural underpinnings are still unclear. The question is how the brain modulates the activity of the reading network according to the novelty of the items. Several models have proposed that familiar and unfamiliar words are not processed by separate networks but rather by common regions operating differently according to familiarity. This hypothesis has proved difficult to test at the neural level because the effects of familiarity and length on reading occur (a) on a millisecond scale, shorter than the resolution of fMRI and (b) in regions which cannot be isolated with non-invasive EEG or MEG. We overcame these limitations by using invasive intra-cerebral EEG recording in epileptic patients. Neural activity (gamma-band responses, between 50 and 150 Hz) was measured in three major nodes of reading network – left inferior frontal, supramarginal, and inferior temporo-occipital cortices – while patients silently read familiar (words) and unfamiliar (pseudo-words) items of two lengths (short composed of one-syllable vs. long composed of three-syllables). While all items elicited strong neural responses in the three regions, we found that the duration of the neural response increases with length only for pseudo-words, in direct relation to orthographic-to-phonological conversion. Our results validate at the neural level the hypothesis that all words are processed by a common network operating more or less efficiently depending on words’ novelty

Public pensions and growth

This paper investigates the relationship between the size of an unfunded public pension system and economic growth in an overlapping generation economy, in which altruistic parents finance the education of their children and leave bequests. Unlike the existing literature, we model intergenerational altruism by assuming that children's income during adulthood is an argument of parental utility. Unfunded public pensions can promote growth when families face liquidity constraints preventing them from investing optimally in the education of their children. We consider two alternative ways of financing a public pension system, either by levying social contributions in a lump-sum manner or in proportion to labour income. We find that there is no case for unfunded public pensions in economies where bequests are operative. By contrast, there exists a growth-maximising size of the public pension system in economies where bequests are not operative and individuals are sufficiently patien

Intergenerational altruism and neoclassical growth models

This paper surveys intergenerational altruism in neoclassical growth models. It first examines Barro's approach to intergenerational altruism, whereby successive generations are linked by recursive altruistic preferences. Individuals have an altruistic concern only for their children, who in turn also have altruistic feelings for their own children. The conditions under which the Ricardian equivalence (debt neutrality) theorem applies are specified. The effectiveness of fiscal policy is further analysed in the context of an economy populated by heterogeneous families differing with respect to their degree of intergenerational altruism. Other forms of altruism, referred to as ad hoc altruism, are also examined, along with their implications for fiscal policy

Reinforced sol–gel thermal barrier coatings and their cyclic oxidation life

Cyclic oxidation life enhancement of sol–gel thermal barrier coatings is obtained via the reinforcement of the controlled micro-crack network that forms during the initial sintering of the deposit. Two different sol–gel methods are used to fill in the process-induced cracks, namely dipcoating and spray-coating. Filling parameters, for instance the number of passes or the viscosity of the sol are adjusted, using various techniques such as profilometry and microstructural analysis, to optimise crack filling. Cyclic oxidation tests are implemented at both 1100C and 1150C to investigate the efficiency of the various reinforcement procedures developed and address the influence of the specific microstructure on the oxidation behaviour