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Search Results: 1 - 10 of 223888 matches for " R. Torrealba "
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Membrane's Discrete Spectrum and BRST Residual Symmetry in the Conformal Light Cone Gauge
R. Torrealba
Physics , 1998,
Abstract: In this work we present a proof of the discreteness of the spectrum for bosonic membrane, in a flat minkowski space. This may be useful to show the quantum mechanical consistence of others bosonics extended models. This proof includes the BRST residual symmetry and was directly performed over the discretized membrane model. The BRST residual invariant effective action is explicity constructed.
Membrane Solitons as Solitary Waves of Non-Linear Strings Dynamics
A. Restuccia,R. Torrealba
Physics , 1997, DOI: 10.1088/0264-9381/15/3/008
Abstract: Families of solutions to the field equations of the covariant BRST invariant effective action of the membrane theory are constructed. The equations are discussed in a double dimensional reduction, they lead to a nonlinear equation for a one dimensional extended object. One family of solutions of these equations are solitary waves with several properties of solitonic solutions in integrable systems, giving evidence that in this double dimensional reduction the nonlinear equations are an integrable system. The other family of solutions found, exploits the property that the non linear system under some assumptions is equivalent to a non linear Schr$\ddot {o}$dinger equation.
Modelaje matemático y simulación de un robot manipulador de microprocesadores: Dos enfoques
Revista de la Facultad de Ingeniería Universidad Central de Venezuela , 2006,
Abstract: this work has educational purposes and constitutes a didactic tool for the teaching of robotics. in particular, the mathematical modelling and simulation of a microprocessors (chips) manipulator robot in electronic board assembling line is presented. the modelling problem is treated using two different approaches: the classical approach using newton?s equations and the energetic approach using lagrange?s equations. the final expressions obtained from these two approaches are compared as well as the development of the models. regarding the final expressions, some differences were found in the models. regarding the development of the model, it was found that the lagrangian approach is simpler than the newtonian approach. this is due to the fact that the lagrangian approach does not require deep knowledge of kinematics and kinetics of rigid bodies, and also because it manipulates scalar equations which are easier to work with than the vectorial equations obtained from newtonian mechanics. with the simulation, the response of the position of the manipulator in presence of different inputs (forces and torques) is studied, being the results of both models practically the same. as real system data was not available, the validation of the models was done as follows: a matrix from minimum-time-positioning curves for each manipulator body (link) was obtained, generating acceleration, velocity and position values for each time instant of the path. then, introducing these values into the respective differential equations, the necessary forces and torques values to make the manipulator tip describe the required path were calculated. finally, these values were introduced as inputs in the simulation, generating the same values of the kinematics variables stated initially as outputs.
La corriente en chorro de bajo nivel sobre los Llanos Venezolanos de Sur América
Eddison R. Torrealba,Jorge A. Amador
Revista de Climatología , 2010,
Abstract: Utilizando observaciones del PACS-SONET (2001-2006), de radiosondeo (2007), de estaciones meteorológicas de superficie y datos del NCEP-NCAR, se analiza y documenta la estructura y variabilidad espacio-temporal de la corriente en chorro de bajo nivel en los Llanos de Venezuela al norte de Sur América. Esta corriente, relativamente menos estudiada que otras en la región, muestra valores medios de 11 m/s durante el verano austral (noviembre-abril) en 925 hPa (750 m.s.n.m., aproximadamente) y con valores de la cortante vertical del viento cercanos a 1 m/s por cada 100 m en el primer km, aproximadamente, con máximos absolutos mayores de 14 m/s en febrero. Arriba de 925 hPa, la corriente disminuye rápidamente a 6 m/s cerca de 700 hPa. Se observa un marcado ciclo diurno, con máximos a las 12:00 UTC y vientos relativamente débiles alrededor de las 21:00 UTC, manifestando fuertes cambios en la cortante vertical del viento en enero-marzo del periodo analizado. La variabilidad intraestacional de la corriente es muy fuerte con periodos hasta de varios días, en los cuales, los vientos asociados a esta corriente son muy débiles. En pocos días, los vientos pueden variar de 25 m/s a valores cercanos a los 5 m/s. Los mecanismos físicos responsables de estos cambios no son evidentes, sin embargo, los mismos muestran una importante relación con los observados en la temperatura cerca de superficie. En algunas estaciones analizadas, la cortante vertical del viento presenta máximos valores durante la época seca y mínimos para la lluviosa, indicando la importancia física de este índice para el desarrollo de la convección. La corriente de bajo nivel también muestra una marcada variabilidad interanual. Respecto a su extensión zonal y meridional, los datos analizados sugieren valores de 1500 km y 500 km, respectivamente.
On the Stability of Compactified D=11 Supermembranes
I. Martin,A. Restuccia,R. Torrealba
Physics , 1997, DOI: 10.1016/S0550-3213(98)00204-1
Abstract: We prove D=11 supermembrane theories wrapping around in an irreducible way over $S^{1} \times S^{1}\times M^{9}$ on the target manifold, have a hamiltonian with strict minima and without infinite dimensional valleys at the minima for the bosonic sector. The minima occur at monopole connections of an associated U(1) bundle over topologically non trivial Riemann surfaces of arbitrary genus. Explicit expressions for the minimal connections in terms of membrane maps are presented. The minimal maps and corresponding connections satisfy the BPS condition with half SUSY.
De Sitter and double irregular domain walls
Rommel Guerrero,R. Omar Rodriguez,R. Ortiz,Rafael Torrealba
Physics , 2005, DOI: 10.1007/s10714-006-0297-y
Abstract: A new method to obtain thick domain wall solutions to the coupled Einstein scalar field system is presented. The procedure allows the construction of irregular walls from well known ones, such that the spacetime associated to them are physically different. As consequence of the approach, we obtain two irregular geometries corresponding to thick domain walls with $dS$ expansion and topological double kink embedded in $AdS$ spacetime. In particular, the double brane can be derived from a fake superpotential.
Las TIC y la metodología de proyectos de aprendizaje: Algunas experiencias en formación docente
Educere , 2008,
Abstract: in this paper some possible links and advantages of the combination of communication and information technologies (cit) and the methodology of learning projects are analyzed. the author shows some experiences on project execution with the help of cits through several years at the upel-maturín. finally, the achievements accomplished in the education of future teachers are analyzed, among them, some finished products such as audiovisuals and educational software where is clear that important changes occurred in self-esteem, confidence and transversality understanding by the students who participated.
Using an Einstein's idea to explain OPERA faster than light neutrinos
Rafael Torrealba
Physics , 2011,
Abstract: The OPERA experiment has reported neutrinos, from the CNGS beam, that arrived to Gran Sasso Laboratory 60ns earlier that expected for light, within a statistical error margin of {\S}6:9 and a systemic error of {\S}7:4. Therefore, these neutrinos are faster than known velocity of the light in vacuum. These puzzling result could be explained by stimulated emission of neutrinos in the decay tunnel, in close analogy with the amplification of a LASER pulse.
"OPERA superluminal neutrinos explained by spontaneous emission and stimulated absorption"
Rafael Torrealba
Physics , 2011,
Abstract: In this work it is shown, that for short 3ns neutrino pulses reported by OPERA, a relativistic shape deforming effect of the neutrino distribution function due to spontaneous emission, produces an earlier arrival of 65.8ns in agreement with the reported 62.1ns\pm 3.7ns, with a RMS of 16.4ns explaining the apparent superluminal effect. It is also shown, that early arrival of long 10500ns neutrinos pulse to Gran Sasso, by 57.8ns with respect to the speed of light, could be explained by a shape deforming effect due to a combination of stimulated absorption and spontaneous emission, while traveling by the decay tunnel that acts as a LASER tube.
Rinofima severo
Tronocoso R,Antonio; Torrealba P,Ramón; Bozán S,Fernando; Lazo C,ángel;
Revista chilena de cirugía , 2012, DOI: 10.4067/S0718-40262012000200015
Abstract: rhinophyma is a progressively growing benign tumor that has the ability to distort the nasal form. even though, it is considered a rare subtype of rosacea, it is of great importance for the ability to create: psychic, aesthetic and functional disorders. this report describes a severe case of rhinophyma in a 52 years old male patient, the medical treatment and the surgical technique used for removal.
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