Constraints on cosmological birefringence energy dependence from CMB polarization data

We study the possibility of constraining the energy dependence of cosmological birefringence by using CMB polarization data. We consider four possible behaviors, characteristic of different theoretical scenarios: energy-independent birefringence motivated by Chern-Simons interactions of the electromagnetic field, linear energy dependence motivated by a 'Weyl' interaction of the electromagnetic field, quadratic energy dependence, motivated by quantum gravity modifications of low-energy electrodynamics, and inverse quadratic dependence, motivated by Faraday rotation generated by primordial magnetic fields. We constrain the parameters associated to each kind of dependence and use our results to give constraints on the models mentioned. We forecast the sensitivity that Planck data will be able to achieve in this respect.Comment: 15 pages, 5 figures. v2 matches JCAP published versio

Is dualism still a source of convergence in Europe?

This paper aims at assessing whether dualistic mechanisms represent a significant component of the aggregate labour productivity convergence observed across the European regions in the 1980s. The potential of an explanation of convergence based - in part, at least - on the existence of dualism in some of the initially poorer regions has been largely ignored by the literature. We use a dualistic model based on Dixit (1970) and on Mas-Colell and Razin (1973) to obtain hypotheses to be tested in cross-region growth regressions. In particular, we wish to test whether a high initial allocation of labour in agriculture in fact generates -- in each sector as well as at the aggregate level -- the specific impact on productivity growth (and therefore on convergence) implied by the theory of the dual economy. We use the data-base Regio-Eu set up by CRENoS, with aggregate and sectoral data for 109 territorial units from 1980 to 1990. Our cross-section results are consistent with the major predictions of the dualistic model. While part of the influence exerted by dualistic mechanisms is not easily distinguishable from the one exerted by other mechanisms such as technology diffusion, still the former appears to be a significant component of the whole process of convergence. Ignoring such component could lead to misleading interpretations of the relative roles played by each of the forces behind the process, and to inexact assessments of what actions should be taken - if any - by the European regional policy to help the process become more pervasive. Keywords: Dualism, Growth, Convergence, Regions, Europe JEL: O40, O41, O52, R11

Growth and sectoral dynamics in the Italian regions

Regional differentials in per capita income and labour productivity in Italy is one of the most notable cases of regional inequality and have attracted attention from economists from all over the world since the 1950s. In this paper we first aim at yielding a comprehensive description of the pattern of regional inequality in Italy on the basis of a new dataset on the main regional variables for the period 1951-94. We use descriptive statistics and panel regression analysis, in order to allow direct comparisons with the impressive evidence available on a large number of national cases. Second, we offer our contribution to the debate about the sources of the persistence of a high degree of regional inequality in Italy. We concentrate on sectoral dynamics in order to assess how much of the initially high potential for convergence due to the dualistic structure of the poorer regions has been exploited, by which regions, under what regional policy regimes. Our analysis remarks that a limited convergence process has occurred over the years 1951-75; afterward the degree of inequality between Northern and Southern regions has increased again. Moreover, the regional distribution of per capita income presents a bimodal polarisation with a rich convergence club which includes most of northern regions, and a poor club made of a small group of non-adriatic southern regions. In the sectoral analysis we find that dual mechanisms play a role in aggregate convergence as long as the outflows of labour from the low productivity agriculture of the poorer regions are a source of expansion of these regions’ industrial sector. Once this migration from agriculture to industry ends in some of these regions, the impact of dualistic mechanisms on convergence weakens significantly. Industrialisation, or its failure, still appears to be the key to understand why some of the lagging regions converge and others do not

Stability of Cubic FAPbI3_3 from X-ray Diffraction, Anelastic, and Dielectric Measurements

Among the hybrid metal-organic perovskites for photovoltaic applications FAPbI_3 (FAPI) has the best performance regarding efficiency and the worst regarding stability, even though the reports on its stability are highly contradictory. In particular, since at room temperature the cubic alpha phase, black and with high photovoltaic efficiency, is metastable against the yellow hexagonal delta phase, it is believed that alpha-FAPI spontaneously transform into delta-FAPI within a relatively short time. We performed X-ray diffraction and thermogravimetric measurements on loose powder of FAPI, and present the first complete dielectric and anelastic spectra of compacted FAPI samples under various conditions. We found that alpha-FAPI is perfectly stable for at least 100 days, the duration of the experiments, unless extrinsic factors induce its degradation. In our tests, degradation was detected after exposure to humidity, strongly accelerated by grain boundaries and the presence of delta phase, but it was not noticeable on the loose powder kept in air under normal laboratory illumination. These findings have strong implications on the strategies for improving the stability of FAPI without diminishing its photovoltaic efficiency through modifications of its composition

European regional growth: do sectors matter?

The recent theoretical and empirical works on economic growth based on Solow’s model have generally neglected the role played by the sectoral mix and structural change on aggregate growth. However, as many development economists have remarked, sectors are characterized by enormous differences in terms of technological change, intersectoral linkages and the degree of scale economies. In this paper we show that indeed sectors matter in determining aggregate growth across European regions. More specifically, we show that large part of convergence is induced by a structural change process of shifting employment from low to high productive sectors that is relatively faster in the initially less productive southern European regions

Technological Catch-Up and Regional Convergence in Europe

Our aim is to address the problem of measuring how much of the convergence observed across European regions is due to convergence in technology versus convergence in capital-labour ratios. To this aim, we first develop a growth model where technology accumulation in lagging regions depends on their own propensity to innovate and on technology diffusion from the leading region, and convergence in per capita income is due to both capital deepening and catch-up. We use data (1980-93) on 109 European regions. Propensities to innovate are computed by assigning each patent collected by the European Patent Office to its region of origin. Our findings are consistent with the hypothesis that technology differs across regions and that convergence is partly due to technological catch-up

Winter habitat selection by the European hare (Lepus europaeus) during feeding activity in a farmland area of southern Tuscany (Italy)

We investigated the winter habitat use by the European hare (Lepus europaeus) at the macro-habitat level in a farmland area of southern Tuscany during feeding activity using spot-light counts. Olive tree groves, cereal stubbles and winter cereals were used more than their availability, whereas ploughed fields, alfalfa and fallow fields were used less than their availability. Olive tree groves were the most used, followed by cereal stubbles. Since approximately 50% of over-wintering cereal stubbles were the result of economic agreements between the hunting district and local farmers, the study confirms the importance of this kind of agro-environmental measure for hare conservation

Disparities In Economic Growth And Unemployment Across The European Regions: A Sectoral Perspective

The picture on disparities in productivity growth and in unemployment across European regions reveals the existence of a slow and not very systematic convergence of labor productivity toward a common level, and of an even more uncertain convergence of unemployment rates. This paper uses a unified framework to study both phenomena. We adopt a three-sector perspective (agriculture, industry and services) to assess whether sectoral dynamics helps explaining the observed heterogeneity in the growth and employment regional performances. The main theoretical hypotheses upon which our empirical investigation is based are obtained by models on the dual-economy (e.g. Mas Colell and Razin 1973), where predictions on how out-migration from agriculture can generate convergence are formulated; and by Baumol (1967), where the role of an expansion of services on aggregate growth is studied. Part of our evidence is based on the use of cluster analysis to identify subsets of regions homogeneous in terms of variables such as sectoral dynamics, labor market dynamics, and overall productivity growth. The results are largely consistent with the adopted theoretical framework. Regions that start from a low agricultural share are the richest and grow relatively slowly; regions that start from very high agricultural shares are characterized by a fast decline of that share and by higher than average growth rates; they also show a limited decline in their employment rates. Regions specialized in service activities show a particularly slow rate of productivity growth and a rising employment rate. More generally, we find a large body of evidence suggesting that convergence in aggregate productivity is strongly associated with out-migration from agriculture, and that the magnitude of the impact of the latter on aggregate regional growth depends significantly on which sector absorbs the migrating workers