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Search Results: 1 - 10 of 150360 matches for " Alexander;Porras-Vázquez "
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Paleomagnetism, structure and 40Ar/39Ar geochronology of the Cerro Mercado pluton, Coahuila: Implications for the timing of the Laramide orogeny in northern Mexico
Molina-Garza, Roberto S.;Chávez-Cabello, Gabriel;Iriondo, Alexander;Porras-Vázquez, Mario Alberto;Terrazas-Calderón, Guillermo Daniel;
Revista mexicana de ciencias geológicas , 2008,
Abstract: the cerro mercado pluton, emplaced in the coahuila fold belt, contains magmatic, ductile, and brittle fabrics that suggest local and regional deformation during igneous emplacement, later affected by regional deformation in the area. the cerro mercado pluton intruded, deformed and uplifted upper cretaceous strata in the southern edge of the central depression of the sabinas basin. a hornblende mineral separate from the pluton yielded a 40ar/39ar plateau age of 44.29 ± 0.19ma (1σ), interpreted as an approximation to the crystallization age of the monzonite. a younger biotite total fusion age of 41.23 ± 0.21 ma (1σ) from a different rock sample is interpreted to represent slow cooling (80°c/ma) of the cerro mercado pluton. paleomagnetic analyses of the pluton yieldwell defined remanent magnetizations of nearly uniform reverse polarity, with a grand mean of d=178.2° and i=-61.7° (n=9 acceptable sites; k=57.5, α.95 = 6.8°). these data are discordant with respect to the eocene reference direction, indicating apparent clockwise rotation (8°) and inclination steepening (21°). the simplest interpretation of the discordance is that northwestward tilting of the pluton occurred during basin inversion within a weakly right lateral transpressive regime with nnw directed contraction. the strain field is consistent with contraction during the laramide orogeny. also, remanence acquisition is contemporaneous with both tectonic and magmatic fabrics in the pluton indicating that it is syntectonic. this suggests - in agreement with stratigraphic data - that the laramide orogeny in central coahuila ended some time after about 44 ma. we propose that reactivation of the san marcos fault and other basement faults in the sabinas basin represents the last manifestation of shortening produced by the laramide orogeny. this was a short episode of deformation that ended by the time of emplacement of younger plutons of the candela-monclova magmatic belt ca. 41 ma. this indicates that culmination
Simplificando el tratamiento quirúrgico de la sonrisa gingival Simplifying the surgical treatment of the gummy smile
H. Chacón Martínez,Y. Castro Govea,S. Pérez Porras,O. Vázquez Costilla
Cirugía Plástica Ibero-Latinoamericana , 2011,
Abstract: La sonrisa es una de las expresiones más comunes del ser humano como muestra de satisfacción, alegría o felicidad. Algunas personas al sonreír muestran la encía por encima de la base de los dientes, lo que ocasiona un aspecto antiestético. Esta situación repercute negativamente en el individuo, ya que altera la espontaneidad de la expresión facial. En el origen de la sonrisa gingival intervienen factores dentales, esqueléticos y de tejidos blandos. Proponemos una variante quirúrgica innovadora para corregir la sonrisa gingival en pacientes con alteraciones de los tejidos blandos. Se intervinieron quirúrgicamente 15 mujeres de entre 17 y 38 a os de edad. En 7 de ellas se practicó rinoplastia además de corrección de la sonrisa gingival. Las 8 restantes se sometieron exclusivamente a corrección de la sonrisa gingival. Las 15 pacientes intervenidas mejoraron su apariencia y autoestima. No hubo complicaciones o problemas relacionados con la herida quirúrgica. Los resultados han sido permanentes a medio y largo plazo. La sonrisa de las pacientes es normal, mejoró su expresión y se conservaron la sensibilidad y la función muscular. La técnica propuesta es sencilla y de fácil reproducción; el tiempo quirúrgico estimado es de una hora y la operación es de tipo ambulatoria. Suele ser bien tolerada por los pacientes y no altera sus actividades cotidianas. Human beings possess a highly expressive face, there are people who when smile, show the gums above the base of the teeth causing an antiesthetic aspect. This situation has negative repercussions altering the spontaneity of the facial expression. In the etiology of the gingival smile, dental, skeletal and soft tissue factors take part. We present a new surgical variant that offers an excellent alternative for the treatment of the gingival smile with soft tissue alterations. Fifteen female patients were treated; 7 had rhinoplasty together with correction of gingival smile; the remaining 8 patients were exclusively gingival smile surgery; ages varied from 17 to 38 years. All the treated improved their appearance and selfesteem. There were no complications or problems related to the wound. The results are permanent in the medium and long term and the patient's smile is normal because of improvement of their expression, maintaining muscular function and sensitivity. The proposed technique is simple, easily reproducible, ambulatory and with an average operating time of one hour. It is well tolerated by the patients since it does not interfere with their daily activities.
The algebraic formalism of soliton equations over arbitrary base fields
A. álvarez Vázquez,J. M. Mu?oz Porras,F. J. Plaza Martín
Mathematics , 1996,
Abstract: The aim of this paper is to offer an algebraic construction of infinite-dimensional Grassmannians and determinant bundles (and therefore valid for arbitrary base fields). As an application we construct the $\tau$-function and formal Baker-Akhiezer functions over arbitrary fields, by proving the existence of a ``formal geometry'' of local curves analogous to the geometry of global algebraic curves. We begin by defining the functor of points, $\fu{\gr}(V,V^+)$, of the Grassmannian of a $k$-vector space $V$ in such a way that its rational points are precisely the points of the Grassmannian defined by Segal-Wilson, although the points over an arbitrary $k$-scheme $S$ have been not previously considered. This definition of the functor $\fu{\gr}(V,V^+)$ allows us to prove that it is representable by a separated $k$-scheme $\gr(V,V^+)$. Using the theory of determinants of Knudsen and Mumford, the determinant bundle is constructed. This is one of the main results of the paper because it implies that we can define ``infinite determinants'' in a completely algebraic way.
Evolución estructural del frente tectónico de la Sierra Madre Oriental en el Ca?ón Santa Rosa, Linares, Nuevo León
Chávez Cabello, Gabriel;Torres Ramos, Jesús Alberto;Porras Vázquez, Nelson Damián;Cossio Torres, Tomás;Aranda Gómez, José Jorge;
Boletín de la Sociedad Geológica Mexicana , 2011,
Abstract: the software 2d move (v. 5.1) was used to perform the structural restoration (inverse deformation modeling) of the folds and thrust faults exposed at the santa rosa canyon, southwest of linares (nuevo león) in the leading edge of the sierra madre oriental (smo) thrust and fold belt. based on detailed mapping we recognized four important faults in the study area: (a) the youngest fault is a structure that propagated from the basement and altered the structural relief between the trailing portion of the structures and the range front of the smo, (b) a secondary reverse fault in the santa rosa bridge area, which thrusts lower cretaceous against upper cretaceous rocks, (c) the main thrust, which has at least 1900 m of structural displacement, and juxtaposes upper jurassic atop upper cretaceous rocks, and lastly, (d) a left-lateral strike-slip fault that cross-cut and displaces nearly 2000 m older structures, such as the hinge zone of the jaures anticline and the frontal thrust of the smo in the area. the structural restoration allowed us to infer the existence of early detachment folds that grew from a weak layer composed by upper jurassic evaporites. we interpret that the detachment folds altered their original geometry as regional shortening increased; thrusting their frontal limbs as a propagating fault and, finally, the structure was transported through the fault and acquired ramp geometry. using the geometric features of the structures, a minimum shortening of 37 % was estimated in the zone with tectonic transport to the east-northeast.
Simplificando el tratamiento quirúrgico de la sonrisa gingival
Chacón Martínez,H.; Castro Govea,Y.; Pérez Porras,S.; Vázquez Costilla,O.; González Cárdenas,H.R.; Mendoza Adam,G.;
Cirugía Plástica Ibero-Latinoamericana , 2011, DOI: 10.4321/S0376-78922011000100005
Abstract: human beings possess a highly expressive face, there are people who when smile, show the gums above the base of the teeth causing an antiesthetic aspect. this situation has negative repercussions altering the spontaneity of the facial expression. in the etiology of the gingival smile, dental, skeletal and soft tissue factors take part. we present a new surgical variant that offers an excellent alternative for the treatment of the gingival smile with soft tissue alterations. fifteen female patients were treated; 7 had rhinoplasty together with correction of gingival smile; the remaining 8 patients were exclusively gingival smile surgery; ages varied from 17 to 38 years. all the treated improved their appearance and selfesteem. there were no complications or problems related to the wound. the results are permanent in the medium and long term and the patient's smile is normal because of improvement of their expression, maintaining muscular function and sensitivity. the proposed technique is simple, easily reproducible, ambulatory and with an average operating time of one hour. it is well tolerated by the patients since it does not interfere with their daily activities.
Algoritmo de compresión para la se?al de pulso arterial periférico
López Delis,Alberto; Vázquez Seisdedos,Carlos; Pascau Simón,Alexander;
Universidad, Ciencia y Tecnología , 2005,
Abstract: the implementation of a compression algorithm for the peripheral arterial pulse signal is presented for the digital photoplethysmography systems with the use of digital signal processors. for the realization of the algorithm the methods discrete fourier transform and discrete cosine transform were used, they allow to carry out an analysis of the energy signal distribution in the transform domain, being able to obtain high compression rates. the results obtained with same test parameters for both transform demonstrate that even when the compression rate is better in the discrete fourier transform the quality in the reconstructed signal is smaller with respect to the discrete cosine transform, being this the best option to be implemented in the processing platform. this algorithm allows an efficient optimization of the memory space as well as a better performance in the data transmission, for the applications implemented in the plethysmography equipment.
Análisis de satisfacción del paciente quirúrgico en oftalmología
Minchón Hernando,A.; Díaz Jiménez,M.; Cutilla Mu?oz,M.A.; De Porras Carrasco,R.; Domínguez García,G.; Vázquez de la Rosa,M.P.;
Enfermería Global , 2011, DOI: 10.4321/S1695-61412011000300020
Abstract: objectives: to understand the perception and assessment of patient satisfaction with surgical pathology operated eyes. identify weaknesses and develop strategies for organizational improvement from the results. material and methods: descriptive, retrospective and transversal. questionnaire conducted with 18 questions. results: patients who answered the questionnaire had a mean age of 70.76 ± 8.9 years. there were 59.37% of men compared with 31.26% of women with a mean wait of 2.2 months until surgery. 64.52% of respondents did not know the name of the nurse. conclusions: the need to implement strategies aimed at improving communication with patients, families and nurses.
Injerto columelar extendido angulado. Método para prevenir la rotación cefálica y lateral de los injertos de cartílago en la punta nasal
Castro Govea,Y.; Fuente del Campo,A.; Chacón Martínez,H.; Pérez Porras,S.; Vázquez Costilla,O.; Mendoza Adam,G.; De la Garza Pineda,O.; Salazar Lozano,A.;
Cirugía Plástica Ibero-Latinoamericana , 2011, DOI: 10.4321/S0376-78922011000200001
Abstract: the mestizo patient usually has a small nose, with wide base, round nostrils and convex dorsum. the alar cartilages are weak, thin and short, providing a deficient structural support and poor definition of the nasal tip. cartilage graft in the nasal tip are very often used to correct this condition, but a commun problem of this procedure is the cephalic or lateral rotation of these grafts. we used an angulated extended collumalar graft to give collumelar support and elongation. the angulated extension of the graft provides a better control and prediction of the position of the grafts of the nasal tip preventing the lateral and cephalic displacement. the surgical protocol included a medical history, development of a surgical plan by analysis of the deformity and the use of pre/and postoperative photographs taken at both intermediate and long time, and long/term follow-up visits for evaluation of the results. ninety-five patients underwent surgery using this procedure: 75 whit an open technique and 20 with a closed technique. follow/up ranged from 6 months to 4 years. the results obtained were satisfactory, showing better control and prediction of the shape of the nasal tip. as a conclusion, in our experiencie, the angulated extended collumelar graft provides better control of the proyection and angularity of cartilage grafts pleced in the nasal tip.
Study of OH-initiated degradation of 2-aminoethanol
M. Karl, C. Dye, N. Schmidbauer, A. Wisthaler, T. Mikoviny, B. D'Anna, M. Müller, E. Borrás, E. Clemente, A. Mu oz, R. Porras, M. Ródenas, M. Vázquez,T. Brauers
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012,
Abstract: The degradation of 2-aminoethanol (MEA) by the hydroxyl radical (OH) was studied in the European Photoreactor (EUPHORE), a large outdoor environmental chamber. High-Temperature Proton-Transfer-Reaction Mass Spectrometry (HT-PTR-MS) and Fast Fourier Transform Infrared (FT-IR) were used to follow concentrations of reactants in the gas phase. Aerosol mass concentrations were tracked with Aerosol Mass Spectrometry (AMS). The chamber aerosol model MAFOR was applied to quantify losses of MEA to the particle phase. The rate constant k(OH + MEA) was determined relative to the rate constant of the 1,3,5-trimethylbenzene reaction with OH and was found to be (9.2 ± 1.1) × 10 11 cm3 molecule 1 s 1, and thus the reaction between OH radicals and MEA proceeds a factor of 2–3 faster than estimated by structure-activity relationship (SAR) methods. Main uncertainty of the relative rate determination is the unknown temporal behaviour of the loss rate of MEA to chamber wall surfaces during the sunlit experiments. Nucleation and growth of particles observed in the experiments could be reproduced by the chamber model that accounted for condensation of gaseous oxidation products, condensation of ethanolaminium nitrate and nucleation involving MEA and nitric acid.
Spectral and Finite Difference Solutions of the Hyperbolic Heat Transport Equation for Thermoelectric Thin Films  [PDF]
Aldo Figueroa, Federico Vázquez
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410A3004
Abstract:

This paper presents the numerical comparison in the solution of the hyperbolic transport Equation that models the heat flux in thermoelectric materials at nanometric length scales when the wave propagation of heat dominates the diffusive transport described by Fourier’s law. The widely used standard finite difference method fails in well-reproducing some of the physics presented in such systems at that length scale level. As an alternative, the spectral methods assure a well representation of wave behavior of heat given their spectral convergence.

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