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Search Results: 1 - 10 of 406502 matches for " P.R. Hernández "
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P.R.Hernández,C.A.Galán,A.Morales,S. Alegret
Journal of applied research and technology , 2003,
Abstract: A portable and low cost measuring system for amperometric chemical sensors using the three-electrodetechnique was developed. This technique allows chemical sensors to work with currents higher than tenmicroamperes. The system was based on a potentiostat operation, completed with an I-V converter andsignal conditioning circuits. The instrument was evaluated comparing calibration curves of hydrogen peroxide,proving several amperometric chemical sensors and biosensors, to those obtained from a very expensivecommercial equipment. Good linearity and sensibility as well as low noise measurements were obtained.Moreover, because the reduced size and low cost, the instrument allows to be used directly in fieldapplications.
Sound speed resolved by photoacoustic technique
Pérez Ruíz, S.J.;Alcántara Iniesta, S;Hernández, P.R.;Casta?eda-Guzmán, R;
Revista mexicana de física , 2007,
Abstract: in this work a new method for measuring the speed of sound in materials is reported. this method uses the photoacoustic effect, which is the generation of sound waves by pulsed optical radiation incident on a material sample. the sound waves generated on the surface of the sample travel through the material and are detected with two piezoelectric sensors separated by a known distance. an appropriate processing of the photoacoustic signal permits the separation of the information of the generated longitudinal waves, of their reflections, as well as of other types of waves generated (shear, surface, etc). the advantages and disadvantages, of this method are discussed in comparison with standard methods.
Optical sensing technique for Young's modulus measurements in piezoelectric materials
Pérez Ruíz, S.J;Montero Díaz, J.A;Alcántara Iniesta, S;Hernández, P.R;Casta?eda G, R;
Revista mexicana de física , 2008,
Abstract: in the design of microsensors using microelectromechanical system (mems) technology, it is necessary to know the elastic properties of the materials employed in their fabrication. reliable mechanical properties of the materials are critical to the safety and correct functioning of these microdevices. mechanical testing of microstructures that are only a few microns thick requires novel techniques and specialized procedures for preparation and handling. in this paper a simplified optic sensing is used to measure the young's modulus in piezoelectric cantilever. this optical technique was chosen because it is the most appropriate when working with small devices, besides being easily implemented and low cost.
Sound speed resolved by photoacoustic technique
S.J. Pérez Ruíz,S. Alcántara Iniesta,P.R. Hernández,R. Casta?eda-Guzmán
Revista mexicana de física , 2007,
Abstract: En el presente trabajo se reporta una técnica novedosa para medir la velocidad del sonido en materiales. Este método de medición utiliza el efecto fotoacústico, que consiste en irradiar una muestra de material con pulsos cortos de radiación láser, registrando la onda acústica generada con dos sensores piezoeléctricos separados por una distancia conocida. Un procesamiento adecuado de la se al fotoacústica permite separar la información de las ondas longitudinales generadas, de sus reflexiones, así como de los frentes de onda de otro tipo de ondas generadas (cortantes, de superficie, etc.). Se discuten sus ventajas y desventajas frente a los métodos usuales.
Efectividad y satisfacción con el tratamiento en pacientes con disfunción eréctil en Espa?a: Estudio EDOS
Martín-Morales,A.; Gutiérrez Hernández,P.R.; Meijide Rico,F.; Arrondo Arrondo,J.L.; Turbí Disla,C.;
Actas Urológicas Espa?olas , 2010, DOI: 10.4321/S0210-48062010000400008
Abstract: introduction: erectile dysfunction (ed) is a worldwide health problem with an ever increasing prevalence, affecting the quality of life of many patients. objective: the aim of this study was to describe treatment effectiveness and patient satisfaction with ed treatment in the spanish cohort of the edos study. material and methods: this observational, pan-european study, assessed treatment effectiveness and patient satisfaction with ed treatment under routine clinical settings, using standard questionnaires. men >18 years about to initiate or change ed treatment were enrolled. patients were assessed at baseline, 3 and 6 months. results: a total of 1,029 patients were analyzed (12.8% of the total european sample). in general, the spanish population characteristics are consistent with the overall population. at baseline 56.6% of patients received tadalafilo, 16.6% sildenafilo, 19.6% vardenafilo, and 7.2% received other treatments. at 3 months, a higher proportion of patients on tadalafil reported improved erections (gaq 1: 96.5% tadalafil, 85.7% sildenafil and 87.2% vardenafil), satisfaction with treatment (edits: 84.2% tadalafil, 75.0% sildenafil and 76.0% vardenafil), and sexual self confidence (sf-pairs: 2.73 tadalafil, 2.39 sildenafil and 2.55 vardenafil), in comparison with sildenafil and vardenafil. at 6 months, differences between treatments were not significant. the mean±sd time elapsed from drug intake to sexual intercourse was higher for patients on tadalafil (18.6±26.4 h) compared to sildenafil (3.6±7.5) and vardenafil (8.6±19.4). conclusion: the longer duration of action for tadalafil, and thus, the longer period of time between dosing and sexual intercourse may contribute to enhance sexual spontaneity, patient satisfaction with the treatment and greater self-confidence.
Intera??o forte e eletromagnetismo
Silva, P.R.;
Revista Brasileira de Ensino de Física , 2008, DOI: 10.1590/S1806-11172008005000005
Abstract: the basic structure of the classical electromagnetism is used as a means to study the strong interaction. the strong coupling constant and the strong field (expessed in terms of an equivalent electric field) inside the nucleon (proton or neutron) are estimated. it is also evaluated the vacuum pressure on the boundary of the nucleon. quark confinement is briefly discussed. simplified versions of the mit bag model are also considered in the present treatment.
Golden Research Thoughts , 2013, DOI: 10.9780/22315063
Abstract: Let us have a look on the following figures of census report of Child Sex ratioThe above report reveals that the child ratio in case of females has dropped; Moreover, such dropping of sex ratio is lowest since Independence We are living in the era of development, we call ourselves civilized and modern but it seems that development to us means developing things rather than developing ourselves.
Stephen Watson: Poet, scholar and critic (1954–2011)
P.R. Anderson
South African Journal of Science , 2011, DOI: 10.4102/sajs.v107i5/6.744
Review of Survey activities 2011: Rock-cored drumlins on Bornholm, Denmark
Jakobsen, P.R.
Geological Survey of Denmark and Greenland Bulletin , 2012,
Die “voorwetenskaplike” geskiedsbewussyn en “vroe wetenskaplike” geskiedskrywing in die Nederduitsch Hervormde Kerk
P.R. Schoeman
HTS Theological Studies/Teologiese Studies , 2009, DOI: 10.4102/hts.v60i4.630
Abstract: The “prescientific” historical awareness and “early scientific” historical writing in the Nederduitsch Hervormde Kerk The scientific practice of Church History within the Nederduitsch Hervormde Kerk van Afrika commenced in 1920 with the submission of S P Engelbrecht’s doctoral thesis. The preliminary era can be typified as the “prescientific” historical awareness that started with an official “Pastoral Writing” by the Synod in 1855 and developed into the “early scientific” historical writing with the writing of Van Warmelo in 1881. This “early scientific” historical writing continued to develop until the early twentieth century. The aim of this article is to explore this era within the “Hervormde” church against the background of a reflection on the scientific nature of ecclesiastically historical research.
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