Volumen 20, Números 1 y 2
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Ítem Soluciones de Einstein no asintóticamente planas(2011-02-11 00:00:00) Alvarado Marín, Rodrigo EduardoIn this paper, a theorem id demostrated regarding the imposibility of the existence od asymptotically plane solutions in spaces with static cylindrycal symmetry, in the framework of the General Theory of Relativity, if the metric is just a function of one coordinate. The question is posed as to whether bodies or systems in the Universe (i.e., cosmic string) may be representable by this metric.Ítem Álgebras-MV artinianas y noetherianas(2011-02-11 00:00:00) Belluce, L. P.We study MV-algebras that satisfacy tha ascending of descending chain conditions on ideals. We demostrarted, for example, if an MV-algebra is artianan, then it has a finite number of minimal prime ideals. We also show the set of impoicative ideals of an MV-algebra satisfies bothchain conditions provided the algebra, modulo its radical is noetherian. Other results relate tha chain conditions to semi-locality.Ítem Aproximación de sucesiones definidas por recurrencia(2011-02-11 00:00:00) Durán, Ana LíaIt is established that recurrent sequences, xn+1 = f(xn),which converge to a fixed point L where the derivative α = f '(L) satisfies 0 < |α| < 1 and where the rest r(x) = f(x) - L - α(x-L) satisfies r(x) = O(|x - L|1+ s), for some s > 0, can be approximated as xn ~ L + cαn for a certain constant c. It is shown that such approximation might fail if only the condition 0 < |α| < 1 is assumed.Ítem Semi- orthogonalities of class of Gauss hypergeometric functions(2011-02-11 00:00:00) Bajpai, S. D.; Arora, M. S.; Mishra, SadhanaWe presented three semi-orthogonalities for a class of Gauss hypergeometric functions. We further employ the semi-orthogonalities to generate a theory concerning finite series expansion involving our hypergeometric functions.Ítem On the right commutativity of loop rings(2011-02-11 00:00:00) Vasantha Kandasamy, W. B.Its proved that extra loops and central loops are conjugated closed, consequently they are G-loops. It is also proved that extra loops and central loops are M-loops.Ítem Procesos emisores de fotones en dispersión de electrones(2011-02-11 00:00:00) Soto Vargas, C. W.The investigations involving the scattering cross sections arising in virtual and real photon emission processes of electron and positron scattering by an atomic nucleus, have the need for thorough and complete calculations of the virtual photon spectrum and the bremsstrahlung related radiation tail. We make a complete review of the plane wave calculations and the introduce the distorted wave formulation, which is mathematically involved and numerically elaborated, but accesible to its use in experimental electron scattering facilities.Ítem Cálculo de las integrales radiales en dispersión de electrones(2011-02-11 00:00:00) Soto Vargas, C. W.The radial integrals which arise from the distorted wave treatment of photon emission process in electron and positron scattering, involve products of the electron`s (or positron`s) ingoing and outgoing wave functions and the radial part of the electromagnetic Green`s function. They can be performed analytically for point Dirac-Coulorab wave functions, but are difficult to evaluate because they involve slowly converging doubly infinite series. We present a discussion and review of the formulation and methods employed to calculate these basic integral at a given value of the energy trafer.Ítem Visualización de plasmas convectivos(2011-02-11 00:00:00) Carboni Méndez, Rodrigo; Páez Portuguez, Jorge EduardoWe present a study of the evolution of magnetic field in plasmas with different conductivities under the influence of a convective movement independent of time, which allows the description of either a single whirlwind, or even a double one, passing through diverse intermediate configurations. Different numerical methods were utilized in order to study the corresponding equations as, i. e, alternate implicit method, method of Crank-Nicholson, weighted ponderer method, and the convective method as well. This last method is used to solve the induction equation of the vector potential as a functions of the field directly. Also, we analized the stability and consistency of the methods, being the most effective the convective method. The model of a convective cell is described by using current functions. By taking two functions each one of those representing a whirlwind, thy can be modified in such a way, that it may represent either a single or a double whirlwind with just the variation of a parameter. The information gained from the evolution of tha magnetic field under such conditions can be depicted graphically in a sequential manner (film), ths allowing the visualization of the evolutions of the magnetic strengh and the density of energy with time within the convective zone. The amplification of the field strength on the periphery of the cell shows the reconnection and disappearance of the magnetic field lines within the cell, with the corresponding decreasing the field strength thereabout until the evolutions reach a steady state. When the Reynolds number is large, a single whirlwind can reach the steady state in a direct manner, while the double whirlwind began to oscillate for all Reynolds numbers values.