Hopf maps as static solutions of the complex eikonal equation

We demonstrate that a class of torus-shaped Hopf maps with arbitrary linking number obeys the static complex eikonal equation. Further, we explore the geometric structure behind these solutions, explaining thereby the reason for their existence. As this equation shows up as an integrability condition in certain non-linear field theories, the existence of such solutions is of some interest.Comment: 13 pages, slight changes in presentation, one paragraph on the symmetries of the eikonal equation added. Version accepted for publication in JM

Investigation on the structural and magnetic properties of sputtered TbFe2/Fe3Ga heterostructures

We have analyzed the structural and magnetic properties of as-grown and annealed [TbFe2/Fe3Ga]n heterostructures grown by sputtering. Evidence of the bcc structure in the Fe3Ga layers has been found. The diffraction peak related to this structure shifts to high angles with the annealing temperature. Also, we have observed a change in the microstructure of the Tb-Fe layers when the thickness layer is reduced in the as-grown heterostructures. Moreover, the Tb content is lower than 33% of the TbFe2 Laves phase and it depends on the layer thickness. The thermal treatments promote the increase of the Tb content, but only in the heterostructures with thick layers. The strong lattice mismatch between the Tb-Fe and Fe-Ga layers seems to prevent a complete Tb diffusion upon the annealing process. Thus, the crystallization of the TbFe2 Laves phase is inhibited in the heterostructures with thin layers, although our experimental results indicate the presence of potential magnetostrictive TbFeGa alloy

A non-parametric microsimulation approach to assess changes in inequality and poverty

This paper presents a non-parametric microsimulation methodology for assessing the impact of labour market changes and government transfers on income inequality and poverty at the household level. The approach assumes that labour markets are segmented and determines (as part of a randomized process) which individuals are expected to move in or out of employment and which move from one employment segment to another based on either known or counterfactual information of aggregate labour market changes. The methodology assumes that the distribution of earnings of those who become employed in a particular segment resembles that of the individuals observed to be employed in that segment. The approach can be effectively combined in top-down fashion with static or dynamic computable general equilibrium (CGE) models, which typically provide insufficient information about household income distribution. The paper discusses the virtues and limitations of applying this methodology and further explains to practitioners how to implement it as a stand-alone methodology or in combination with a CGE model. It also shows how the methodology can be generalized to also capture the poverty and inequality effects of changes in non-labour incomes, such as government transfers. One great advantage of this method is that it is not very demanding in terms of modelling labour supply and household behaviour as compared with alternative parametric approaches, while at the same time providing a plausible link between changes in overall labour market conditions and the full household income distribution.

Impact of the global crisis on the achievement of the MDGs in Latin America

Progress towards the MDGs is expected to slow as a consequence of the global economic downturn. This study applies an economy-wide framework to analyze the impact of the crisis on MDG achievement in six Latin American countries. It finds significant setbacks towards the goals and, in the case of the region’s low-income countries, the cost of achieving these would rise between 1.6 and 3.4 per cent of GDP per year between 2010 and 2015 as compared with a no-crisis scenario. The additional public spending would contribute to economic growth though not sufficiently for full recovery to pre-crisis growth.computable general equilibrium models, distribution, welfare and poverty, foreign aid, macroeconomic analyses of economic development

On abstraction-carrying code and certificate-size reduction

Abstraction-Carrying Code (ACC) is a framework for mobile code safety in which the code supplier provides a program together with an abstraction (or abstract model of the program) whose validity entails compliance with a predefined safety policy. The abstraction plays thus the role of safety certificate and its generation is carried out automatically by a fixed-point analyzer. The advantage of providing a (fixed-point) abstraction to the code consumer is that its validity is checked in a single pass (i.e., one iteration) of an abstract interpretation-based checker. A main challenge to make ACC useful in practice is to reduce the size of certificates as much as possible, while at the same time not increasing checking time. Intuitively, we only include in the certificate the information which the checker is unable to reproduce without iterating. We introduce the notion of reduced certifícate which characterizes the subset of the abstraction which a checker needs in order to validate (and re-construct) the full certificate in a single pass. Based on this notion, we show how to instrument a generic analysis algorithm with the necessary extensions in order to identify the information relevant to the checker

A Non-Parametric Microsimulation Approach to Assess Changes in Inequality and Poverty

This paper presents a non-parametric microsimulation methodology for assessing the determinants of changes in income inequality and poverty. One great advantage of this method over alternatives is that it is not very demanding in terms of modelling labour supply and household behaviour while still providing a plausible link between changes in overall labour market conditions and the full household income distribution. The paper also shows how the method can be adapted to assess the poverty and inequality effects of changes in non-labour incomes (such as through a government transfer programme) and how it can be combined with economy-wide models.Non-parametric simulation methods; Computable General Equilibrium Models; Income Distribution; Employment, Unemployment, and Wages; Measurement and Analysis of Poverty; Effects of Welfare Programs; Supply and Demand for Labour; Segmented Labour Markets