Many economists have observed that wealth is systematically lower in the tropics than elsewhere (Sala-i Martin, 1997; Nordhaus, 2006). Determining why this is remains a major puzzle. Leading hypotheses include, inter alia, the tropics’s disease burden (Gallup, Sachs and Mellinger, 1999), biota available for domestication (Diamond, 1997), distance from trading partners (Frankel and Romer, 1999),...

This review outlines the history of our knowledge of the neuropharmacology of 5-hydroxytryptamine (5-HT; serotonin), focusing primarily on the work of U.K. scientists. The existence of a vasoconstrictive substance in the blood has been known for over 135 years. The substance was named serotonin and finally identified as 5-HT in 1949. The presence of 5-HT in the brain was reported by Gaddum in 1...

in this work, a new iterative method is proposed for obtaining the approximate solution of a class of hammerstein type integral equations system. the main structure of this method is based on the richardson iterative method for solving an algebraic linear system of equations. some conditions for existence and unique solution of this type equations are imposed. convergence analysis and error bou...