Gendered dynamics of transnational social protection

Social protection refers to resources and strategies to deal with social risks, such as poverty or obligations and needs of care, which might impede the realization of life chances and well-being. Previous research has shown that migrants are particularly affected by challenges when accessing or providing social protection, because of unfamiliar welfare regulations in the immigration country and their family and friends being located in various locations, calling for an investigation of gendered dynamics in transnational spaces. In this issue we aim to advance these vital debates by elucidating the social consequences of the articulation and organization of formal and informal social protection across borders for different actors involved through a joint investigation of gender and transnationality as key dimensions of social inequality. More specifically, the papers collected in this issue are devoted to investigating the link of formal and informal dimensions of transnational social protection and showing its impact on unequal life chances of mobile people in Europe. This introduction frames the articles collected in this issue from an inequality perspective, thereby pointing to the ways in which gender and transnationality interact with other dimensions of inequality in the field of social protection, which currently constitutes one of the most vital issues in the field of migration scholarship

Parametric phenomena of the particle dynamics in a periodic gravitational wave field

We establish exactly solvable models for the motion of neutral particles, electrically charged point and spin particles (U(1) symmetry), isospin particles (SU(2) symmetry), and particles with color charges (SU(3) symmetry) in a gravitational wave background. Special attention is devoted to parametric effects induced by the gravitational field. In particular, we discuss parametric instabilities of the particle motion and parametric oscillations of the vectors of spin, isospin, and color charge.Comment: 26 pages, to be published in J. Math. Phy

Lattice study of classical inflaton decay

We study numerically the decay of the inflaton by solving the full non-linear equations of motion on the lattice. We confirm that parametric resonance is effective in transferring energy from the inflaton to a scalar field as long as the self-interactions of the second field are very small. However, in the very broad resonance case (q>>1) the decay rate is limited by scatterings, which significantly slows down the decay. We also find that the inflaton cannot decay via parametric resonance into a scalar field with moderate self-interactions. This means that the preheating stage may be completely absent in many natural inflationary models.Comment: 12 pages LaTeX with standard RevTex macros, uses epsf.sty. 7 postscript figures (included). No changes. Replaced to correct a problem with the figure

A Consistency Relation for Power Law Inflation in DBI models

Brane inflation in string theory leads to a new realization of power law inflation which can give rise to significant non-gaussianity. This can happen for any throat geometry if the scalar potential is appropriate. This note presents a consistency relation connecting the running of the nonlinearity parameter characterizing the non-gaussianity and the scalar and tensor indices. The relationship is valid assuming that the throat geometry and scalar potential support power law inflation, regardless of the level of non-gaussianity.Comment: Added references, a couple of comments, fixed 3 typo

On the Scalability of Constraint Solving for Static/Off-Line Real-Time Scheduling

International audienceRecent papers have reported on successful application of constraint solving techniques to off-line real-time scheduling problems, with realistic size and complexity. Success allegedly came for two reasons: major recent advances in solvers efficiency and use of optimized, problem-specific constraint representations. Our current objective is to assess further the range of applicability and the scalability of such constraint solving techniques based on a more general and agnostic evaluation campaign. For this, we have considered a large number of synthetic scheduling problems and a few real-life ones, and attempted to solve them using 3 state-of-the-art solvers, namely CPLEX, Yices2, and MiniZinc/G12. Our findings were that, for all problems considered, constraint solving does scale to a certain limit, then diverges rapidly. This limit greatly depends on the specificity of the scheduling problem type. All experimental data (synthetic task systems, SMT/ILP models) are provided so as to allow experimental reproducibility

On the Scalability of Constraint Solving for Static/Off-Line Real-Time Scheduling

Recent papers have reported on successful application of constraint solving techniques to off-line real-time scheduling problems, with realistic size and complexity. Success allegedly came for two reasons: major recent advances in solvers efficiency and use of optimized, problem-specific constraint representations. Our current objective is to assess further the range of applicability and the scalability of such constraint solving techniques based on a more general and agnostic evaluation campaign. For this, we have considered a large number of synthetic scheduling problems and a few real-life ones, and attempted to solve them using 3 state-of-the-art solvers, namely CPLEX, Yices2, and MiniZinc/G12. Our findings were that, for all problems considered, constraint solving does scale to a certain limit, then diverges rapidly. This limit greatly depends on the specificity of the scheduling problem type. All experimental data (synthetic task systems, SMT/ILP models) are provided so as to allow experimental reproducibility

N-flation from multiple DBI type actions

In this letter we present a new N-flation model constructed by making use of multiple scalar fields which are being described by their own DBI action. We show that the dependence of the e-folding number and of the curvature perturbation on the number of fields changes compared with the normal N-flation model. Our model is also quite different from the usual DBI N-flation which is still based on one DBI action but involves many moduli components. Some specific examples of our model have been analyzed.Comment: 4 pages, 1 figur

Inflaton Decay and Heavy Particle Production with Negative Coupling

We study the decay of the inflaton in a renormalizable two scalar theory. Since the dynamics of the system is dominated by states with large occupation numbers which admit a semiclassical description, the decay can be studied by solving the classical equations of motion on the lattice. Of particular interest is the case when the cross-coupling between the inflaton and the second scalar field is negative, which is naturally allowed in many realistic models. While the inflaton decays via parametric resonance in the positive coupling case we find that for negative coupling there is a new mechanism of particle production which we call negative coupling instability. Due to this new mechanism the variances of the fields grow significantly larger before the production is shut off by the backreaction of the created particles. We also find that heavy particles are produced much more efficiently with negative coupling, which is of prime importance for GUT baryogenesis. Using a simple toy model for baryogenesis and the results of our lattice simulations we show that for natural values of the cross-coupling enough 10^{14}GeV bosons are created to produce a baryon to entropy ratio consistent with observation. For positive coupling the value of the cross-coupling required to produce such massive particles is unnaturally large. In addition to our numerical results we obtain analytical estimates for the maximum variances of the fields in an expanding universe for all cases of interest in our model.Comment: 41 pages + 12 figures, Latex with standard Revtex macro

Fluctuations in the Cosmic Microwave Background I: Form Factors and their Calculation in Synchronous Gauge

It is shown that the fluctuation in the temperature of the cosmic microwave background in any direction may be evaluated as an integral involving scalar and dipole form factors, which incorporate all relevant information about acoustic oscillations before the time of last scattering. A companion paper gives asymptotic expressions for the multipole coefficient $C_\ell$ in terms of these form factors. Explicit expressions are given here for the form factors in a simplified hydrodynamic model for the evolution of perturbations.Comment: 35 pages, no figures. Improved treatment of damping, including both Landau and Silk damping; inclusion of late-time effects; several references added; minor changes and corrections made. Accepted for publication in Phys. Rev. D1

Assisted Inflation from Geometric Tachyon

We study the effect of rolling of N D3-branes in the vicinity of NS5-branes. We find out that this system coupled with the four dimensional gravity gives the slow roll assisted inflation of the scalar field theory. Once again this expectation is exactly similar to that of N-tachyon assisted inflation on unstable D-branes.Comment: 15 pages, 3 figures, minor modifications, to appear in JHE