Social Security and Retirement across OECD Countries

There are large differences in the employment to population ratio relative to the US across OECD countries, and these differences are even larger for the old age (55-69 years). There are also large differences in various features of social security, such as the replacement rate, the entitlement age or whether it is allowed to collect social security and working. These observations suggest that they might be an important factor. I assess quantitatively this hypothesis using a life cycle general equilibrium model of retirement. I find that the differences in social security can indeed account for the differences in employment to population ratio at old age in the OECD. I also evaluate which features of social security are most important in this context and find that generosity and whether it allows collecting social security while working are the most important contributors

Social security and retirement across OECD countries

There are large differences in the employment to population ratio relative to the US across OECD countries, and these differences are even larger for the old age (55-69 years). There are also large differences in various features of social security, such as the replacement rate, the entitlement age or whether it is allowed to collect social security while working. These observations suggest that they might be an important contributing factor in accounting for differences in retirement. I assess quantitatively the importance of these features using a life cycle general equilibrium model of retirement. I find that the differences in social security account for 90% of the differences in employment to population ratio at ages 60-64 in the OECD. The differences in the replacement rates and whether the system allows for collecting social security while working are the most important contributing factors to account for the differences in retirement.Social security, retirement, idiosyncratic labor income risk

Social Security and Retirement across OECD Countries

There are large differences in the employment to population ratio relative to the US across OECD countries, and these differences are even larger for the old age (55-69 years). There are also large differences in various features of social security, such as the replacement rate, the entitlement age or whether it is allowed to collect social security and working. These observations suggest that they might be an important factor. I assess quantitatively this hypothesis using a life cycle general equilibrium model of retirement. I find that the differences in social security can indeed account for the differences in employment to population ratio at old age in the OECD. I also evaluate which features of social security are most important in this context and find that generosity and whether it allows collecting social security while working are the most important contributors.Social security, retirement, idiosyncratic labor income risk

Fault-tolerant computer architecture based on INMOS transputer processor

Redundant processing was used for several years in mission flight systems. In these systems, more than one processor performs the same task at the same time but only one processor is actually in real use. A fault-tolerance computer architecture based on the features provided by INMOS Transputers is presented. The Transputer architecture provides several communication links that allow data and command communication with other Transputers without the use of a bus. Additionally the Transputer allows the use of parallel processing to increase the system speed considerably. The processor architecture consists of three processors working in parallel keeping all the processors at the same operational level but only one processor is in real control of the process. The design allows each Transputer to perform a test to the other two Transputers and report the operating condition of the neighboring processors. A graphic display was developed to facilitate the identification of any problem by the user

Chiral phases of two-dimensional hard-core bosons with frustrated ring-exchange

We study the zero temperature phase diagram of two-dimensional hard-core bosons on a square lattice with nearest neighbour and plaquette (ring-exchange) hoppings, at arbitrary densities, by means of a hierarchical mean-field theory. In the frustrated regime, where quantum Monte Carlo suffers from a sign problem, we find a rich phase diagram where exotic states with nonzero chirality emerge. Among them, novel insulating phases, characterized by nonzero bond-chirality and plaquette order, are found over a large region of the parameter space. In the unfrustrated regime, the hierarchical mean-field approach improves over the standard mean-field treatment as it is able to capture the transition from a superfluid to a valence bond state upon increasing the strength of the ring-exchange term, in qualitative agreement with quantum Monte Carlo results

Staircase of crystal phases of hard-core bosons on the Kagome lattice

We study the quantum phase diagram of a system of hard-core bosons on the Kagome lattice with nearest-neighbor repulsive interactions, for arbitrary densities, by means of the hierarchical mean field theory and exact diagonalization techniques. This system is isomorphic to the spin S=1/2 XXZ model in presence of an external magnetic field, a paradigmatic example of frustrated quantum magnetism. In the non-frustrated regime, we find two crystal phases at densities 1/3 and 2/3 that melt into a superfluid phase when increasing the hopping amplitude, in semi-quantitative agreement with quantum Monte Carlo computations. In the frustrated regime and away from half-filling, we find a series of plateaux with densities commensurate with powers of 1/3. The broader density plateaux (at densities 1/3 and 2/3) are remnants of the classical degeneracy in the Ising limit. For densities near half-filling, this staircase of crystal phases melts into a superfluid, which displays finite chiral currents when computed with clusters having an odd number of sites. Both the staircase of crystal phases and the superfluid phase prevail in the non-interacting limit, suggesting that the lowest dispersionless single-particle band may be at the root of this phenomenon

Spatial correlations in nonequilibrium reaction-diffusion problems by the Gillespie algorithm

We present a study of the spatial correlation functions of a one-dimensional reaction-diffusion system in both equilibrium and out of equilibrium. For the numerical simulations we have employed the Gillespie algorithm dividing the system in cells to treat diffusion as a chemical process between adjacent cells. We find that the spatial correlations are spatially short ranged in equilibrium but become long ranged in nonequilibrium. These results are in good agreement with theoretical predictions from fluctuating hydrodynamics for a one-dimensional system and periodic boundary conditions.Comment: 11 pages, 4 figure

Breached pairing in trapped three-color atomic Fermi gases

We introduce an exactly solvable model for trapped three-color atom gases. Applications to a cigar-shaped trapped cold fermions reveal a complex structure of breached pairing phases. We find two competing superfluid phases at weak and intermediate couplings, each one with two color pair condensates, that can be distinguished from density profile measurements.Comment: 4 pages, 5 figure

Multimodal Corpora in Second Language Acquisition of English as a Lingua Franca

After exploring the characteristics of intemational English, its wide range of varieties comprended in World Englishes, and the use it shows as a Lingua Franca (ELF); we realize that current English language manifest more variations, language changes and multilingualism than any other language. Departing from these premises, the logical path takes us to understand the impact produced in the ways we acquire English as a second language. Traditional SLA procedures denote obsolescence when approaching ELF. We are then incited to move in the direction of new models that achieve success in ELF. Here, corpora proves to be a useful tool, and particularly multimodal corpora, that shows inspiring results.Departamento de Filología InglesaGrado en Estudios Inglese