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Search Results: 1 - 10 of 33406 matches for " Juan Ramirez-Castaneda "
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Long-Term Efficacy and Safety of Botulinum Toxin Injections in Dystonia
Juan Ramirez-Castaneda,Joseph Jankovic
Toxins , 2013, DOI: 10.3390/toxins5020249
Abstract: Local chemodenervation with botulinum toxin (BoNT) injections to relax abnormally contracting muscles has been shown to be an effective and well-tolerated treatment in a variety of movement disorders and other neurological and non-neurological disorders. Despite almost 30 years of therapeutic use, there are only few studies of patients treated with BoNT injections over long period of time. These published data clearly support the conclusion that BoNT not only provides safe and effective symptomatic relief of dystonia but also long-term benefit and possibly even favorably modifying the natural history of this disease. The adverse events associated with chronic, periodic exposure to BoNT injections are generally minor and self-limiting. With the chronic use of BoNT and an expanding list of therapeutic indications, there is a need to carefully examine the existing data on the long-term efficacy and safety of BoNT. In this review we will highlight some of the aspects of long-term effects of BoNT, including efficacy, safety, and immunogenicity.
Embedding PV and WF Models into Steady State Studies by an Optimization Strategy  [PDF]
Juan Manuel Ramirez
Smart Grid and Renewable Energy (SGRE) , 2011, DOI: 10.4236/sgre.2011.23027
Abstract: Modeling of photovoltaic (PV) and wind farms (WF) stations to take into account these renewable energies into the power flow formulation are summarized. A strategy based on multi objective optimization in order to allocate PV and WF power into electrical power system is proposed. It is assumed that there are a reduced number of choices to allocate the stations. The algorithm is applied to the 39-bus test power system. The results show that the proposed algorithm is capable of optimal placement of renewable units.
Study of cylindrically symmetric solutions in metric f(R) gravity with constant R
Monica Tatiana Rincon-Ramirez,Leonardo Castaneda
Physics , 2013,
Abstract: Solutions for cylindrically symmetric spacetimes in f(R) gravity are studied. As a first approach, R=constant is assumed. A solution was found such that it is equivalent to a result given by Azadi et al. for R=0 and a metric was found for R=constant different from zero. Comparison with the case of general relativity with cosmological constant is made and the metric constants are given in terms of \Lambda. Overlap with arXiv:0810.4673 [gr-qc] by A. Azadi, D. Momeni and M. Nouri-Zonoz
Boundary Term in Metric f(R) Gravity: Field Equations in the Metric Formalism
Alejandro Guarnizo,Leonardo Castaneda,Juan M. Tejeiro
Physics , 2010, DOI: 10.1007/s10714-010-1012-6
Abstract: The main goal of this paper is to get in a straightforward form the field equations in metric f(R) gravity, using elementary variational principles and adding a boundary term in the action, instead of the usual treatment in an equivalent scalar-tensor approach. We start with a brief review of the Einstein-Hilbert action, together with the Gibbons-York-Hawking boundary term, which is mentioned in some literature, but is generally missing. Next we present in detail the field equations in metric f(R) gravity, including the discussion about boundaries, and we compare with the Gibbons-York-Hawking term in General Relativity. We notice that this boundary term is necessary in order to have a well defined extremal action principle under metric variation.
Shear Dynamics in Bianchi I Cosmology
Diego Caceres,Leonardo Castaneda,Juan M. Tejeiro
Physics , 2010,
Abstract: We present the exact equation for evolution of Bianchi I cosmological model, considering a non-tilted perfect fluid in a matter dominated universe. We use the definition of shear tensor and later we prove it is consistent with the evolution equation for shear tensor obtained from Ricci identities and widely known in literature [3], [5], [9]. Our result is compared with the equation given by Ellis and van Elst in [3] and Tsagas, Challinor and Maartens [5]. We consider that it is important to clarify the notation used in [3], [5] related with the covariant derivative and the behavior of the shear tensor.
Geodesic Deviation Equation in f(R) Gravity
Alejandro Guarnizo,Leonardo Castaneda,Juan M. Tejeiro
Physics , 2010, DOI: 10.1007/s10714-011-1194-6
Abstract: In this paper we study the Geodesic Deviation Equation (GDE) in metric f(R) gravity. We start giving a brief introduction of the GDE in General Relativity in the case of the standard cosmology. Next we generalize the GDE for metric f(R) gravity using again the FLRW metric. A generalization of the Mattig relation is also obtained. Finally we give and equivalent expression to the Dyer-Roeder equation in General Relativity in the context of f(R) gravity.
Modeling of Multi-Pulse VSC Based SSSC and STATCOM  [PDF]
Pavel Zuniga- Haro, Juan Manuel Ramirez
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.23022
Abstract: The aim of this paper is to contribute to the dynamic modeling of multi-pulse voltage sourced converter based static synchronous series compensator and static synchronous compensator. Details about the internal functioning and topology connections are given in order to understand the multi-pulse converter. Using the 24 and 48-pulse topologies switching functions models are presented. The models correctly represent commutations of semiconductor devices in multi-pulse converters, which consequently allows a precise representation of harmonic components. Additionally, time domain models that represent harmonic components are derived based on the switching functions models. Switching functions, as well as time domain models are carried out in the original abc power system coordinates. Effectiveness and precision of the models are validated against simulations performed in Matlab/Simulink®. Additionally, in order to accomplish a more realistic comparison, a laboratory prototype set up is used to assess simulated waveforms.
Modes of Discourse - Ways for Thinking. Actual Debates in Socio-Cultural Studies
Juan D. Ramirez
Philosophica , 1995,
Systems and Categories
Juan Pablo Ramirez
Mathematics , 2015,
Abstract: The attempt is to give a formal concpet of system, and with this provide a definition of category, that will also satisfy the definition of a system. An axiomatic base is given, for constructing the group of integers. In the process, we define a group of automorphisms; we are defining an ordered group of functors with a natural transformation between any two. We give an isomorphism from the group of integers into the group of automorphisms, as guaranteed by Cayley's Theorem. The ultimate aim is to use these definitions and concepts, of system and category, to give a general description of mathematics. The third chapter is dedicated to set theory and we provide a proof of the Yoneda Lemma. This is used to prove Cayley's theorem. We see how this relates to the construction of the integers, before introducing representable functors. After lattices, we devote a chapter to group theory. We conlcude with a brief description of topological systems; we describe them as functors on algebraic categories, with a subset of invariant objects. This new version includes a first description of linear spaces. The section for operations has been rewritten and corrected.
Evolution of magnetic fields through cosmological perturbation theory
Hector J. Hortua,Leonardo Castaneda,Juan M. Tejeiro
Physics , 2011, DOI: 10.1103/PhysRevD.87.103531
Abstract: The origin of galactic and extra-galactic magnetic fields is an unsolved problem in modern cosmology. A possible scenario comes from the idea of these fields emerged from a small field, a seed, which was produced in the early universe (phase transitions, inflation, ...) and it evolves in time. Cosmological perturbation theory offers a natural way to study the evolution of primordial magnetic fields. The dynamics for this field in the cosmological context is described by a cosmic dynamo like equation, through the dynamo term. In this paper we get the perturbed Maxwell's equations and compute the energy momentum tensor to second order in perturbation theory in terms of gauge invariant quantities. Two possible scenarios are discussed, first we consider a FLRW background without magnetic field and we study the perturbation theory introducing the magnetic field as a perturbation. The second scenario, we consider a magnetized FLRW and build up the perturbation theory from this background. We compare the cosmological dynamo like equation in both scenarios.
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