The Solow model in discrete time and decreasing population growth rate

This paper reformulates the neoclassical Solow-Swan model of economic growth in discrete time by introducing a generic population growth law that verifies the following properties: 1) population is strictly increasing and bounded 2) the rate of growth of population is decreasing to zero as time tends to infinity. We show that in the long run the capital per worker of the model converges to the non-trivial steady state of the Solow Swan model with zero labor growth rate. In addition we prove that the solutions of the model are asymptotically stable.Solow model

Further Criteria for the Existence of Steady Line-Driven Winds

In Paper I, we showed that steady line-driven disk wind solutions can exist by using "simple" models that mimic the disk environment. Here I extend the concepts introduced in Paper I and discuss many details of the analysis of the steady/unsteady nature of 1D line-driven winds. This work confirms the results and conclusions of Paper I, and is thus consistent with the steady nature of the 1D streamline line-driven disk wind models of Murray and collaborators and the 2.5D line-driven disk wind models of Pereyra and collaborators. When including gas pressures effects, as is routinely done in time-dependent numerical models, I find that the spatial dependence of the nozzle function continues to play a key role in determining the steady/unsteady nature of supersonic line-driven wind solutions. I show here that the existence/nonexistence of local wind solutions can be proved through the nozzle function without integrating the equation of motion. This work sets a detailed framework with which we will analyze, in a following paper, more realistic models than the "simple" models of Paper I.Comment: 30 pages, 5 figures, accepted for publication by The Astrophysical Journa

Analysis of the convergence of the 1/t and Wang-Landau algorithms in the calculation of multidimensional integrals

In this communication, the convergence of the 1/t and Wang - Landau algorithms in the calculation of multidimensional numerical integrals is analyzed. Both simulation methods are applied to a wide variety of integrals without restrictions in one, two and higher dimensions. The errors between the exact and the calculated values of the integral are obtained and the efficiency and accuracy of the methods are determined by their dynamical behavior. The comparison between both methods and the simple sampling Monte Carlo method is also reported. It is observed that the time dependence of the errors calculated with 1/t algorithm goes as N^{-1/2} (with N the MC trials) in quantitative agreement with the simple sampling Monte Carlo method. It is also showed that the error for the Wang - Landau algorithm saturates in time evidencing the non-convergence of the methods. The sources for the error are also determined.Comment: 8 pages, 5 figure

Learning strategies in modelling economic growth

Cornerstone economic growth models as the Solow-Swan model and their modern extensions normally assume the rate of population growth as exogenous without any explanation of the links between economic growth and most important demographic variables. Recently, some articles have presented models to explain many phenomena of population dynamics, including evolution and ageing. This paper is a first exercise to include endogenous population dynamics and learning strategies as ingredients of an economic growth model. The model includes two ways of learning that determinate economic growth: individual and social learning. We study the dynamics through computer simulations and we show that the model reflects some features of real economies.Economic Growth, Learning Strategies, Human Capital, Penna model

Propósitos de una experiencia formativa con jóvenes : el sentido de las prácticas socioeducativas como vínculo entre educación y trabajo social

El objetivo de esta comunicación es reflexionar sobre nuestra propuesta de formación del curso Educación y Trabajo Social, analizando la integración de los saberes del campo de la pedagogía y del trabajo social, en torno a las prácticas socioeducativas como experiencia formativa. Analizaremos la configuración de la propuesta pedagógica centrándonos en la relación entre enseñanza, aprendizaje y prácticas socioeducativas, como eje de la formación para la intervención profesional. En esta reflexión consideramos a la Enseñanza como una práctica social, que se conforma a través de un proceso de interacción socio-histórica, cultural y política que promueve la formación. Por ello, proponemos la formación del/de la futuro/a profesional en trabajo social, incentivando la construcción de saberes en torno a la cuestión social vinculados con el ámbito socioeducativo, mediante el análisis de problemáticas comunitarias situadas, desde una perspectiva socio-pedagógica en función de la cual, orienta su práctica de intervención en la comunidad en el marco de programas institucionales de nuestra unidad académica.Fil: Pereyra, Sonia N.. Universidad Nacional de San Luis.Fil: Calderón, Marcela I.. Universidad Nacional de San Luis

Fast Algorithm to Calculate Density of States

An algorithm to calculate the density of states, based on the well-known Wang-Landau method, is introduced. Independent random walks are performed in different restricted ranges of energy, and the resultant density of states is modified by a function of time, F(t)=1/t, for large time. As a consequence, the calculated density of state, gm(E,t), approaches asymptotically the exact value gex(E) as 1/sqrt(t), avoiding the saturation of the error. It is also shown that the growth of the interface of the energy histogram belongs to the random deposition universality class.Comment: 5 pages, 5 figure