Brain Drain and Distance to Frontier

In this paper we investigate the effects of emigration on growth in developing countries.We present a model in which productivity increases either through imitation or innovation, and both activities use the same types of human capital as inputs, albeit with different intensities.Heterogenous agents accumulate human capital responding to economic incentives, and might be able to emigrate.When no migration of skilled workers is allowed, backwards countries converge to the technological frontier.The possibility of migration, however, distorts the optimal accumulation of human capital and slows down, or even hinders, development.This effect is stronger the farther away a developing country is from the technological frontier.Thus, technologically backward countries are more likely to suffer from a negative brain drain effect.Among these countries, those which implement appropriate policies, subsidizing the accumulation of the most useful type of human capital, improve their growth performance.They converge faster, and possibly to a higher productivity level than countries where such policies are neglected.Education;Migration;Human capital;Economic growth

Carbon Leakage Revisited: Unilateral Climate Policy with Directed Technical Change

The increase in carbondioxide emissions by some countries in reaction to an emission reduction by countries with climate policy (carbon leakage) is seen as a serious threat to unilateral climate policy.Using a two-country model where only one of the countries enforces an exogenous cap on emissions, this paper analyzes the effect of technical change that can be directed towards the clean or dirty input, on carbon leakage.We show that, as long as technical change cannot be directed, there will always be carbon leakage through the standard terms-of-trade effect.However, once we allow for directed technical change, a counterbalancing induced technology effect arises and carbon leakage will generally be lower.Moreover, we show that when the relative demand for energy is sufficiently elastic, carbon leakage may be negative: the technology effect induces the unconstrained region to voluntarily reduce its own emissions.Keywords

Choosing the direction:Investment, the environment and economic development

Is technological change good for the environment in a globalized world, or does it rather lead to more pollution? Do climate policies represent worthy attempts to preserve the environment for future generations, or are they just pointless burdens on economic systems? Do efforts to increase the level of education in developing countries lead to faster economic growth, or are they just a waste of already scarce resources? These are some of the themes investigated in this dissertation: the aim of this work is to contribute some answers to questions that touch our life, every day. The focus of this thesis is on the interrelations between technological change, environmental policy and environmental quality, on the one hand; and between technological change, human capital accumulation and economic development, on the other. This work points out that, to understand these complex phenomena, we need to take into account both the general equilibrium features of the problems, i.e. the feed-backs between technological change and inputs (such as resources and skills) supply; and the dynamic issues involved, i.e. the evolution over time of the level, and of the composition of technology and inputs.

Recurring patterns in stationary intervals of abdominal uterine electromyograms during gestation

Abdominal uterine electromyograms (uEMG) studies have focused on uterine contractions to describe the evolution of uterine activity and preterm birth (PTB) prediction. Stationary, non-contracting uEMG has not been studied. The aim of the study was to investigate the recurring patterns in stationary uEMG, their relationship with gestation age and PTB, and PTB predictivity. A public database of 300 (38 PTB) three-channel (S1-S3) uEMG recordings of 30 min, collected between 22 and 35 weeks' gestation, was used. Motion and labour contraction-free intervals in uEMG were identified as 5-min weak-sense stationarity intervals in 268 (34 PTB) recordings. Sample entropy (SampEn), percentage recurrence (PR), percentage determinism (PD), entropy (ER), and maximum length (L MAX) of recurrence were calculated and analysed according to the time to delivery and PTB. Random time series were generated by random shuffle (RS) of actual data. Recurrence was present in actual data (p<0.001) but not RS. In S3, PR (p<0.005), PD (p<0.01), ER (p<0.005), and L MAX (p<0.05) were higher, and SampEn lower (p<0.005) in PTB. Recurrence indices increased (all p<0.001) and SampEn decreased (p<0.01) with decreasing time to delivery, suggesting increasingly regular and recurring patterns with gestation progression. All indices predicted PTB with AUC≥0.62 (p<0.05). Recurring patterns in stationary non-contracting uEMG were associated with time to delivery but were relatively poor predictors of PTB

Choosing the Direction: Investment, the Environment and Economic Development.

Is technological change good for the environment in a globalized world, or does it rather lead to more pollution? Do climate policies represent worthy attempts to preserve the environment for future generations, or are they just pointless burdens on economic systems? Do efforts to increase the level of education in developing countries lead to faster economic growth, or are they just a waste of already scarce resources? These are some of the themes investigated in this dissertation: the aim of this work is to contribute some answers to questions that touch our life, every day. The focus of this thesis is on the interrelations between technological change, environmental policy and environmental quality, on the one hand; and between technological change, human capital accumulation and economic development, on the other. This work points out that, to understand these complex phenomena, we need to take into account both the general equilibrium features of the problems, i.e. the feed-backs between technological change and inputs (such as resources and skills) supply; and the dynamic issues involved, i.e. the evolution over time of the level, and of the composition of technology and inputs.

Random laser from engineered nanostructures obtained by surface tension driven lithography

The random laser emission from the functionalized thienyl-S,S-dioxide quinquethiophene (T5OCx) in confined patterns with different shapes is demonstrated. Functional patterning of the light emitter organic material in well defined features is obtained by spontaneous molecular self-assembly guided by surface tension driven (STD) lithography. Such controlled supramolecular nano-aggregates act as scattering centers allowing the fabrication of one-component organic lasers with no external resonator and with desired shape and efficiency. Atomic force microscopy shows that different geometric pattern with different supramolecular organization obtained by the lithographic process tailors the coherent emission properties by controlling the distribution and the size of the random scatterers

Experimental evidence of replica symmetry breaking in random lasers

Spin-glass theory is one of the leading paradigms of complex physics and describes condensed matter, neural networks and biological systems, ultracold atoms, random photonics, and many other research fields. According to this theory, identical systems under identical conditions may reach different states and provide different values for observable quantities. This effect is known as Replica Symmetry Breaking and is revealed by the shape of the probability distribution function of an order parameter named the Parisi overlap. However, a direct experimental evidence in any field of research is still missing. Here we investigate pulse-to-pulse fluctuations in random lasers, we introduce and measure the analogue of the Parisi overlap in independent experimental realizations of the same disordered sample, and we find that the distribution function yields evidence of a transition to a glassy light phase compatible with a replica symmetry breaking.Comment: 10 pages, 5 figure

Mirabilia Coralii. Capolavori barocchi in corallo tra maestranze ebraiche e trapanesi

La pregevole lavorazione del corallo trapanese ricostruita attraverso la puntuale analisi delle fonti documentarie, manoscritte e bibliografiche. L’organizzazione della maestranza e il ruolo che la committenza,sia laica che ecclesiastica, ha esercitato nella realizzazione di capolavori oggi presenti in rinomate collezioni pubbliche e private e nei principali musei nazionali ed internazionali. Una rassegna di importanti manufatti, un tempo mirabili opere da Wunderkammer, criticamente commentata, che bene evidenzia l’aulica produzione siciliana ricercata da Sovrani, Viceré ed alti prelati. Un’originale ed inedita trattazione che per la prima volta rende noti nomi e biografie di gran parte degli artisti specializzati, tra XVI e XIX secolo, nella trasformazione del prezioso materiale marin