Matematicas

Este trabajo es el producto del Seminario de Investigación sobre Configuraciones Centrales impartido por el Dr. Ernesto Pérez Chavela, entre septiembre del 2000 y abril de 2001. Se divide el trabajo en dos Capítulos: El Capítulo 1 trata los aspectos generales de la Mecánica Celeste. Se estudia el problema newtoniano de los n-cuerpos describiendo explícitamente las ecuaciones de movimiento que lo rigen, sus integrales clásicas y sus simetrías. Se muestra que en dicho problema general no
existen soluciones de equilibrio, muchas veces llamadas puntos de equilibrio.
Al considerar que la complejidad de los movimientos aumenta rápidamente con el número de masas, se analiza el problema con dos cuerpos haciendo una descripción cualitativa de todas sus soluciones. Unicamente cuando n = 2 , se conocen explícitamente todas las soluciones. Implicando que este problema en particular sea muy importante dentro de la Mecánica Celeste. También se hace mención de las soluciones particulares que se conocen del problema newtoniano de los n-cuerpos, las cuales dicho sea de paso, se obtienen de las Configuraciones Centrales que a su vez, se estudian y tratan en el Capítulo 2 como objetivo a priori de la presente disertación.

682 26-1 In the last five chapters we discussed electrostatics — the physics of stationary charges. In this and the next chapter, we discuss the physics of electric currents — that is, charges in motion. Examples of electric currents abound and involve many professions. Mete-orologists are concerned with lightning and with the less dramatic slow flow of charge through the atmosphere. Biologists, physiologists, and engineers working in medical technology are concerned with the nerve currents that control muscles and especially with how those currents can be reestablished after spinal cord injuries. Electrical engineers are concerned with countless electrical systems, such as power systems, lightning protection systems, information storage systems, and music systems. Space engineers monitor and study the flow of charged particles from our Sun because that flow can wipe out telecommunication systems in orbit and even power transmission systems on the ground. In this chapter we discuss the basic physics of electric currents and why they can be established in some materials but not in others. We begin with the meaning of electric current. 26-2 Electric Current Although an electric current is a stream of moving charges, not all moving charges constitute an electric current. If there is to be an electric current through a given surface, there must be a net flow of charge through that surface. Two examples clarify our meaning. 1. The free electrons (conduction electrons) in an isolated length of copper wire are in random motion at speeds of the order of 10 6 m/s. If you pass a hypothetical plane through such a wire, conduction electrons pass through it in both directions at the rate of many billions per second — but there is no net transport of charge and thus no current through the wire. However, if you connect the ends of the wire to a battery, you slightly bias the flow in one direction, with the result that there now is a net transport of charge and thus an electric current through the wire. 2. The flow of water through a garden hose represents the directed flow of positive charge (the protons in the water molecules) at a rate of perhaps several million coulombs per second. There is no net transport of charge, however, because there is a parallel flow of negative charge (the electrons in the water molecules) of exactly the same amount moving in exactly the same direction. In this chapter we restrict ourselves largely to the study — within the framework of classical physics — of steady currents of conduction electrons moving through metallic conductors such as copper wires.

16 Existen 14 integrales directas: 6 de las funciones, 6 de los cuadrados y 2 múltiplos. 17 La integral de una función trigonométrica abajo se utiliza su recíproco. 18 La pareja de: Sen  coseno, Tan  sec 2 , Ctg  csc 2 19 Integral con 1 + o -1 y una relación trigonométrica abajo sin su derivada arriba, se multiplica por el binomio conjugado. 20 Si una integral de funciones trigonométricas no se puede entender se expresa toda en función de senos y coseno.

Fue fundada en 1975 por Bill Gates y Paul Allen, está dedicada al sector del hardware y software. Cuenta con más de 93 mil empleados en 102 países; sólo en 2012 registró un ingreso por 72 mil millones 360 mil dólares. Ha sido acusada en EU por prácticas monopólicas. Ramo tecnológico.

In this research paper, we made an analysis of Multinomial models through simulation; this was done under correct and incorrect assumptions on the data generating process. Also, it was analyzed the performance of the models under different sample sizes. It was found that a correct specified model with samples of 200 or more observations achieves estimators which are unbiased and consistent, while incorrect assumptions about the data generating process causes biased and inconsistent estimators. On the other hand, conditional models with small sample sizes imply bad statistical properties, especially when Probit models are estimated.

Regulación y bienestar económico: Evaluación de la regulación de servicios públicos domiciliarios de acueducto y electricidad en Colombia en los noventa. El caso de Empresas Públicas de Medellín Resumen: Las reformas de los noventa introdujeron cambios institucionales y metodológicos en la regulación tarifaria para los servicios de electricidad y acueducto en Colombia. Este artículo, además de reseñar dichos cambios, evalúa el bienestar a través de un contrafactual y el cálculo de la variación equivalente. Con el contrafactual se analiza cómo hubiese sido la evolución tarifaria de no haberse presentado la reforma de los noventas, mientras que con la variación equivalente se establece el cambio del bienestar de los consumidores. Para el cálculo de la variación equivalente se estiman las elasticidades precio y gasto para dichos servicios mediante el Sistema Casi Ideal de Demanda. En general, se concluye que la regulación generó una pérdida en el bienestar de los consumidores.

Cholinesterase inhibitors vary in their selectivity for acetylcholinesterase versus butyrylcholinesterase. We examined several cholinesterase inhibitors and assessed the relative role of acetylcholinesterase versus butyrylcholinesterase inhibition in central and peripheral responses to these medications. Donepezil and icopezil are highly selective for acetylcholinesterase, whereas tacrine and heptylphysostigmine demonstrated greater potency for butyrylcholinesterase over acetylcholinesterase. All four compounds increased acetylcholine levels in mouse brains. Dose -response curves for tremor (central effect) and salivation (peripheral effect) showed that donepezil and icopezil possess a more favourable therapeutic index than the nonselective inhibitors, tacrine and heptylphysostigmine. Co-administration of the selective butyrylcholinesterase inhibitor tetraisopropylpyrophosphoramide (iso-OMPA) potentiated peripheral, but not central, effects of the selective acetylcholinesterase inhibitor icopezil. The improved therapeutic index observed in mice with icopezil is due to a high degree of selectivity for acetylcholinesterase versus butyrylcholinesterase, suggesting that high selectivity for acetylcholinesterase may contribute to the clinically favourable tolerability profile of agents such as donepezil in Alzheimer's disease patients. D