Immigration and the pension system in Spain

In this paper we use a large overlapping generations model with individuals that differ across age, productivity and native status to assess the effects on the pension system of different immigration quotas in the context of an aging population by computing how much should social security taxes be rised in order to pay for the pension burden in two model economies. The first one is the standard model pioneered by Auerbach and Kotlikoff (1987) where skilled and unskilled workers are perfect substitutes in the production process. In the second model economy, individuals with different skill levels are imperfect substitutes as in Canova and Ravn (1998). The main result of the paper is that half of the reduction of the social security tax rate associated with immigration in the standard model is lost when skilled and unskilled individual are imperfect substitutes. Consequently, the standard model with perfect substitution overestimates the ability of immigration inflows to sustain the pension system in Spain

Non-symmetric gravity waves on water of infinite depth

Two different numerical methods are used to demonstrate the existence of and calculate non-symmetric gravity waves on deep water. It is found that they appear via spontaneous symmetry-breaking bifurcations from symmetric waves. The structure of the bifurcation tree is the same as the one found by Zufiria (1987) for waves on water of finite depth using a weakly nonlinear Hamiltonian model. One of the methods is based on the quadratic relations between the Stokes coefficients discovered by Longuet-Higgins (1978a). The other method is a new one based on the Hamiltonian structure of the water-wave problem

Symmetry breaking in periodic and solitary gravity-capillary waves on water of finite depth

A weakly nonlinear model is developed from the Hamiltonian formulation of water waves, to study the bifurcation structure of gravity-capillary waves on water of finite depth. It is found that, besides a very rich structure of symmetric solutions, non-symmetric Wilton's ripples exist. They appear via a spontaneous symmetry breaking bifurcation from symmetric solutions. The bifurcation tree is similar to that for gravity waves. The solitary wave with surface tension is studied with the same model close to a critical depth. It is found that the solution is not unique, and that further non-symmetric solitary waves are possible. The bifurcation tree has the same structure as for the case of periodic waves. The possibility of checking these results in low-gravity experiments is postulated

Decreasing Inequality Under Latin America's "Social Democratic" and " Populist" Govenments: Is the Difference Real?

This paper addresses the claim that the governments of Argentina, Bolivia, Ecuador and Venezuela, Latin America's so-called "left-populist" governments, have failed to effectively reduce inequality in the 2000s and have only benefitted from high commodity prices and other benign external conditions. In particular, it examines the econometric evidence presented by McLeod and Lustig (2011) that the "social democratic" governments of Brazil, Chile and Uruguay were more successful and finds that their original results are highly sensitive to the use of data from the Socioeconomic Database for Latin America and the Caribbean (SEDLAC). Conducting the same analysis using data on income inequality from the Economic Commission for Latin America and the Caribbean (ECLAC) leads to the exact opposite result: it is the so-called "left-populist" governments who appear to have effectively reduced income inequality over the last decade. The key difference between data from SEDLAC and ECLAC is that the latter corrects for income underreporting -- when households in an income survey underreport their true amount of income, thus biasing the measurement of inequality -- while the former does not. Absent reasonable criteria for choosing one dataset over the other, the paper suggests that any econometric results based on income inequality data should prove robust to both sources

Increasing Public Perceptions of Stroke

Analysis of publicly available data for the selected county of Rutland Vermont was performed to understand the underlying health problems affecting the county. Although VT overall has better health status indicators, including better access to care, and lower rates of chronic diseases than the nation, pockets of the state have higher rates of chronic diseases including obesity, DM, and cerebrovascular accidents. Increasing awareness of stroke risk factors and symptoms is a cost-effective method to reduced stroke burden and provide successful treatment.https://scholarworks.uvm.edu/fmclerk/1621/thumbnail.jp

Oscillatory spatially periodic weakly nonlinear gravity waves on deep water

A weakly nonlinear Hamiltonian model is derived from the exact water wave equations to study the time evolution of spatially periodic wavetrains. The model assumes that the spatial spectrum of the wavetrain is formed by only three free waves, i.e. a carrier and two side bands. The model has the same symmetries and invariances as the exact equations. As a result, it is found that not only the permanent form travelling waves and their stability are important in describing the time evolution of the waves, but also a new kind of family of solutions which has two basic frequencies plays a crucial role in the dynamics of the waves. It is also shown that three is the minimum number of free waves which is necessary to have chaotic behaviour of water waves

How to discriminate easily between Directed-percolation and Manna scaling

Here we compare critical properties of systems in the directed-percolation (DP) universality class with those of absorbing-state phase transitions occurring in the presence of a non-diffusive conserved field, i.e. transitions in the so-called Manna or C-DP class. Even if it is clearly established that these constitute two different universality classes, most of their universal features (exponents, moment ratios, scaling functions,...) are very similar, making it difficult to discriminate numerically between them. Nevertheless, as illustrated here, the two classes behave in a rather different way upon introducing a physical boundary or wall. Taking advantage of this, we propose a simple and fast method to discriminate between these two universality classes. This is particularly helpful in solving some existing discrepancies in self-organized critical systems as sandpiles.Comment: 7 Pages, 4 Figure

Evolutionary comparison between viral lysis rate and latent period

Marine viruses shape the structure of the microbial community. They are, thus, a key determinant of the most important biogeochemical cycles in the planet. Therefore, a correct description of the ecological and evolutionary behavior of these viruses is essential to make reliable predictions about their role in marine ecosystems. The infection cycle, for example, is indistinctly modeled in two very different ways. In one representation, the process is described including explicitly a fixed delay between infection and offspring release. In the other, the offspring are released at exponentially distributed times according to a fixed release rate. By considering obvious quantitative differences pointed out in the past, the latter description is widely used as a simplification of the former. However, it is still unclear how the dichotomy "delay versus rate description" affects long-term predictions of host-virus interaction models. Here, we study the ecological and evolutionary implications of using one or the other approaches, applied to marine microbes. To this end, we use mathematical and eco-evolutionary computational analysis. We show that the rate model exhibits improved competitive abilities from both ecological and evolutionary perspectives in steady environments. However, rate-based descriptions can fail to describe properly long-term microbe-virus interactions. Moreover, additional information about trade-offs between life-history traits is needed in order to choose the most reliable representation for oceanic bacteriophage dynamics. This result affects deeply most of the marine ecosystem models that include viruses, especially when used to answer evolutionary questions.Comment: to appear in J. Theor. Bio