Immigration and Pension Benefits in the Host-country

This paper examines the role that low-skilled immigrant labor force plays in determining the benefits of the public pension of the host population. With an overlapping-generations model in continuous time which allows to identify which groups of native population are better or worse off with immigration and a fully redistributive pension system, we find that the retirement benefits and hence the welfare levels of the host population are affected in a different way whether sharing or not pension benefits with immigrants. In this sense, the youngest local population may prefer, contrary to the oldest ones, a policy of closed borders.Immigration, welfare, pension benefits.

Defined Contribution vs Defined Pension: Reforming the Legal Retirement Age

In this paper we analyze the effects of changing Social Security parameters on the optimal legal retirement age. Two Social Security Systems are studied, with opposite results. When the pension scheme has a defined contribution, a more redistributive system will delay the preferred legal retirement age. On the other hand, when the pension benefit is the defined parameter, the increase in the redistribution level will lower this preferred age.

On the variational homotopy perturbation method for nonlinear oscillators

In this paper we discuss a recent application of a variational homotopy perturbation method to rather simple nonlinear oscillators . We show that the main equations are inconsistent and for that reason the results may be of scarce utility

Wave localization in strongly nonlinear Hertzian chains with mass defect

We investigate the dynamical response of a mass defect in a one-dimensional non-loaded horizontal chain of identical spheres which interact via the nonlinear Hertz potential. Our experiments show that the interaction of a solitary wave with a light intruder excites localized mode. In agreement with dimensional analysis, we find that the frequency of localized oscillations exceeds the incident wave frequency spectrum and nonlinearly depends on the size of the intruder and on the incident wave strength. The absence of tensile stress between grains allows some gaps to open, which in turn induce a significant enhancement of the oscillations amplitude. We performed numerical simulations that precisely describe our observations without any adjusting parameters.Comment: 4 pages, 5 figures, submitted for publicatio

An unexpected actor in ammonium assimilation in conifer trees

Conifers are tree species with enormous environmental and economic interests but with several characteristics that complicate their investigation (big size, secondary compounds, large long-life cycles, megagenomes…). However, they are well adapted to ammonium-rich soils being a good model to study ammonium assimilation in plants. Although they have a special feature, only two glutamine synthetase (GS, EC 6.3.1.2) genes, GS1a and GS1b, coding for cytosolic proteins, have been identified. In angiosperms and in the gymnosperm Ginkgo biloba there are two types of this enzyme responsible of the ammonium assimilation: GS1 expressed in the cytosol and GS2 in the plastids. Until the date, the searches of new GS1 and GS2 genes in conifers have been made with classical biochemical and molecular biology techniques without satisfactory results. In the present context, the emergence of the next generation sequencing (NGS) techniques has open new opportunities in the resolution of old problems. They have allowed the whole sequencing of the massive conifer genomes and the analysis of their transcriptomes. Thus, in the framework of the European project ProCoGen, a gene expression atlas of the tissues of one-month seedlings was carried out using laser capture microdissection (LCM) and massive sequencing in maritime pine (Pinus pinaster), which is a conifer tree from the Southwestern Mediterranean region1. From the analysis of this work, a new gene coding for a new putative cytosolic GS has been identified, PpGS1c. 1Cañas, RA et al. (2017). Plant J, 91. 1064-1087Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Project funding by Ministerio de Economía y Competitividad BIO2015-69285-R and MicroNUpE (BIO2015-73512-JIN; MINECO/AEI/FEDER, UE

Geometric structures on loop and path spaces

Is is known that the loop space associated to a Riemannian manifold admits a quasi-symplectic structure. This article shows that this structure is not likely to recover the underlying Riemannian metric by proving a result that is a strong indication of the "almost" independence of the quasi-symplectic structure with respect to the metric. Finally conditions to have contact structures on these spaces are studied.Comment: Final version. To appear in Proceedings of Math. Sci. Indian Academy of Science