Sowing legume-rich pastures make compatible an increase in production with the conservation of plant diversity of mediterranean dehesas

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WAS MALTHUS RIGHT? A VAR ANALYSIS OF ECONOMIC AND DEMOGRAPHIC INTERACTIONS IN PRE-INDUSTRIAL ENGLAND

This paper shows that the interaction between economic and demographic variables in England before the onset of modern economic growth did not fit some crucial assumptions of the Malthusian model. I estimated a vector autoregression for data on fertility, nuptiality, mortality and real wages over the period 1541-1840 applying a well-known identification strategy broadly used in macroeconomics. The results show that endogenous adjustment of population to real wages functioned as Malthus assumed only until the 17th century: positive checks disappeared during the 17th century and preventive checks disappeared before 1740. This implies that the endogenous adjustment of population levels to changes in real wages -one of the cornerstones of the Malthusian model- did not work during an important part of the period usually considered within the “Malthusian regime”.

An analysis of a regular black hole interior model

We analyze the thermodynamical properties of the regular static and spherically symmetric black hole interior model presented by Mboyne and Kazanas. Equations for the thermodynamical quantities valid for an arbitrary density profile are deduced, and from them we show that the model is thermodynamically unstable. Evidence is also presented pointing to its dynamical instability. The gravitational entropy of this solution based on the Weyl curvature conjecture is calculated, following the recipe given by Rudjord, Gr$\varnothing$n and Sigbj$\varnothing$rn, and it is shown to have the expected behavior.Comment: 22 pages, 17 figures, accepted for publication in International Journal of Theoretical Physic

Adult mortality and investment: a new explanation of the English agricultural productivity in the 18th century.

We claim that the exogenous decline of adult mortality at the end of the seventeenth century can be one of the causes driving both the decline of interest rate and the increase in agricultural production per acre in preindustrial England. Following the intuition of the life-cycle hypothesis, we show that the increase in adult life expectancy must have implied less farmer impatience and it could have caused more investment in nitrogen stock and land fertility, and higher production per acre. We analyse this dynamic interaction using an overlapping generation model and show that the evolution of agricultural production and capital rates of return predicted by the model coincide fairly well with their empirical pattern.

Regional index of sustainable economic well-being development project: final report

This report presents results from a development project carried out by nef (the new economics foundation) on behalf of emda (the East Midlands Development Agency) and Natural England, to improve the methodologies used in the calculation of the R-ISEW (Regional Index of Sustainable Economic Well-Being)

Towards Modeling HIV Long Term Behavior

The precise mechanism that causes HIV infection to progress to AIDS is still unknown. This paper presents a mathematical model which is able to predict the entire trajectory of the HIV/AIDS dynamics, then a possible explanation for this progression is examined. A dynamical analysis of this model reveals a set of parameters which may produce two real equilibria in the model. One equilibrium is stable and represents those individuals who have been living with HIV for at least 7 to 9 years, and do not develop AIDS. The other one is unstable and represents those patients who developed AIDS in an average period of 10 years. However, further work is needed since the proposed model is sensitive to parameter variations.Comment: Accepted in proceedings of 18th IFAC World Congress, Milan, August 28 - September 2, 2011 (Invited Contribution: Modeling methods and clinical applications in medical and biological systems I). 6 pages, 7 figure

Mu-tau neutrino refraction and collective three-flavor transformations in supernovae

We study three-flavor collective neutrino transformations in the dense-neutrino region above the neutrino sphere of a supernova core. We find that two-flavor conversions driven by the atmospheric mass difference and the 13-mixing angle capture the full effect if one neglects the second-order difference between the muon and tau neutrino refractive index. Including this "mu-tau matter term" provides a resonance at a density of approximately 3 x 10^7 g cm^-3 that typically causes significant modifications of the overall electron neutrino and antineutrino survival probabilities. This effect is surprisingly sensitive to deviations from maximal 23-mixing, being different for each octant.Comment: 9 pages, 7 figures. New presentation of results, version to be published in PR