Emissions evolved from the pyrolysis and combustion of polyvinyl chloride (PVC) were studied at four different temperatures (500, 700,
850 and 1000 °C) in a horizontal laboratory tubular quartz reactor in order to analyse the influence of both temperature and…

A review of all known descriptions of immature stages of the species of the genera Scaeva Fabricius, 1805, Ischiodon Sack, 1913 and Simosyrphus Bigot, 1882 is presented using SEM illustrations. The third instar larval and/or pupal morphology of Scaeva dignota…

El acuífero del Valle de Toluca, localizado en el Altiplano Mexicano, se encuentra sometido a una intensa explotación para cubrir las necesidades de agua en el propio valle, así como parte de las de Ciudad de México. Los altos niveles…

Numerical calculation of Fresnel patterns through fast Fourier transforms usually requires an extremely large number of samples in order to fulfil the Nyquist sampling condition. In many applications, the cut-off frequency of the system is much below the limit fixed…

Objectives: The fall of the Wall in 1989 can be seen as a natural experiment in the epidemiological sense to further examine the relation between democracy and health. Design and setting: Ecological study in the 23 post-communist countries, during the…

Choline, the precursor and the metabolite of acetylcholine, is reputed as a selective α7 nicotinic receptor agonist. In this study, however, we
have seen that choline exerted a dual effect on bovine nicotinic receptors expressed in Xenopus oocytes. On the…

This paper uses dynamic general equilibrium and computational methods, inspired by the multi-sector growth model structure in Stephen Turnovsky's work, to develop a theory that unifies two of the traditional explanations of structural change: sector-biased technical change and non-homothetic preferences.…

A new analytical approximate expression for the period of the simple pendulum is obtained by using a heuristic but pedagogical derivation. This formula depends on two parameters obtained by comparing term-by-term the power-series expansions of the approximate and exact expressions…

Two Lidstedt-Poincaré perturbation based methods are used to solve the nonlinear differential equation of a nonlinear oscillator having the square of the angular frequency depends quadratically on the velocity. Mickens published two interesting papers [1, 2] about this oscillator and…

A procedure to determine the best image range of distances that can be obtained from an aphakic eye is presented. Corneal surfaces are calculated from videokeratographic data. Light distributions at different distances inside the eye are calculated with a near-field…