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Search Results: 1 - 10 of 66015 matches for " álvaro Hernández-Martínez "
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Loculated hydrothorax: An unusual complication of hepatic cirrhosis Hidrotórax loculado: una complicación inusual de la cirrosis hepática
Rogger álvaro Bendezú-García,Marta Lázaro-Sáez,álvaro Hernández-Martínez,Gustavo Oliver Patrón-Román
Revista Espa?ola de Enfermedades Digestivas , 2013,
Abstract:
Efectos de los activos familiares en la selección de actividades y en el ingreso de los hogares rurales de México
Antonio Yúnez Naude,álvaro Meléndez-Martínez
Investigación económica , 2007,
Abstract:
Skeletons of 3D Surfaces Based on the Laplace-Beltrami Operator Eigenfunctions  [PDF]
Adolfo Horacio Escalona-Buendia, Lucila Ivonne Hernández-Martínez, Julio Roberto Murillo-Torres, Omar Nieto-Crisóstomo, Rarafel Martínez-Vega
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.62038
Abstract: In this work we describe the algorithms to construct the skeletons, simplified 1D representations for a 3D surface depicted by a mesh of points, given the respective eigenfunctions of the Discrete Laplace-Beltrami Operator (LBO). These functions are isometry invariant, so they are independent of the object’s representation including parameterization, spatial position and orientation. Several works have shown that these eigenfunctions provide topological and geometrical information of the surfaces of interest [1] [2]. We propose to make use of that information for the construction of a set of skeletons, associated to each eigenfunction, which can be used as a fingerprint for the surface of interest. The main goal is to develop a classification system based on these skeletons, instead of the surfaces, for the analysis of medical images, for instance.
Brief Review of Numerical Simulation Applied to Solve Oil Extraction Problems  [PDF]
M. M. Onofre-Ramos, L. Casta?eda, E. Austria-Aguilar, E. E. Hernández-Martínez, A. Oropeza-Osornio
International Journal of Geosciences (IJG) , 2015, DOI: 10.4236/ijg.2015.65041
Abstract: In the last decades, the numerical analysis has abridged the time and cost of oil extractive operations, and thus their implementation has been promoted so much that today is used to solve a large number of phenomena that occur during the extraction of hydrocarbons, not only economizing the operation, but also shedding light to the phenomenon, and helping to have a better understanding. Nevertheless in spite of the success of the applications of numerical simulations, it has been until today, looking for their optimization, because the discretization methods of the domain and the model are through meshes, which require modifying the physics of the problem so that this matches the numerical method, and not in backwards.
Cytotoxic Effect of Methanol Extracts and Partitions of Two Mexican Desert Plants against the Murine Lymphoma L5178Y-R  [PDF]
Ramiro Quintanilla-Licea, Ricardo Gomez-Flores, Mario ángel Samaniego-Escamilla, Humberto Carlos Hernández-Martínez, Patricia Tamez-Guerra, Rolando Morado-Castillo
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.711143
Abstract: Pachycereus marginatus (DC.) Britton & Rose and Ibervillea sonorae (S. Watson) Greene have been used in the Mexican traditional medicine for the treatment of various diseases, including cancer. The present study aims to investigate the cytotoxic activity of these plants against a murine lymphoma. Soxhlet extraction of dried and powdered plant material was performed with methanol. Also, a further partitioning of these methanolic extracts with hexane and ethyl acetate was achieved. The in vitro cytotoxic activity against the murine lymphoma L5178Y-R cell line was assessed via the colorimetric MTT assay. The methanol extract from P. marginatus exhibited high cytotoxic activity (up to 94%) at concentrations ranging from 3.9 to 500 μg/mL; however, hexane and ethyl acetate partitions from this methanolic extract showed lower but significant (p < 0.05) concentration-dependent cytotoxicity (hexane partition up to 94% at 500 μg/mL; ethyl acetate partition up to 94% at 65.5 μg/mL). The methanolic extract and partitions derived from I. sonorae also showed significant (p < 0.05) and concentration-dependent cytotoxicity against L5178Y-R cells at concentrations ranging from 7.81 to 500 μg/mL (methanolic
Ctla-4, una molécula que inhibe la activación de los linfocitos T
Cecilia Fernández-Ponce,Juan David Hernández-Martínez,Carlos Silvera-Redondo
Revista Salud Uninorte , 2006,
Abstract: CTLA-4 (Antígeno-4 asociado al Linfocito T Citotóxico) es una molécula expresada en la superficie de la mayoría de los linfocitos T activados. Su función es regular la homeostasis y la tolerancia periférica inmunológica inhibiendo la activación de los linfocitos T. Dos mecanismos han sido postulados para mediar la inhibición por CTLA-4 de la respuesta de los linfocitos T: Se alización negativa y antagonismo competitivo de la vía de coestimulación mediada por CD28/B7. Las diferentes moléculas que participan en la activación e inactivación de los linfocitos T han sido analizadas con el objetivo de dise ar estrategias terapéuticas de tolerancia inmunológica. Los progresos han estado basados en los mecanismos de activación linfocitaria, la coestimulación o la se alización por citocinas, pero ha sido difícil dise ar terapias de inhibición endógena. La molécula CTLA-4 ha sido el blanco de muchos estudios, los cuales han planteado diferentes estrategias novedosas para inducir inmunosupresión, algunos antígeno específicos, que se han convertido en nuevos pilares en el tratamiento de las enfermedades autoinmunes y rechazo de transplantes.
La problemática en la taxonomía de los recursos genéticos de tejocote (Crataegus spp.) en México
Nú?ez-Colín, Carlos Alberto;Hernández-Martínez, Miguel ángel;
Revista mexicana de ciencias agrícolas , 2011,
Abstract: the genus crataegus (rosaceae subtribe pyrinae) is one of the most difficult to treat taxonomic complexes. furthermore, past mistakes are being repeated today by publications misclassifying specimens of the genus crataegus, just as there are scientific names that cause confusion when identifying taxonomic identities. due to this, the present study aims to describe the problems that exist in published taxonomies of the genus, mainly in mexico, and thus try to clarify the best way to systematize of systematic of the genetic resources of the genus crataegus. it also attempts to identify the geographical origin of tejocote (crataegus spp.). the genus crataegus presents reproductive complications known as "the crataegus problem". moreover, in mexico, only two taxonomic treatments in this respect, one in the early twentieth century and the other only focused on the northern and part of central mexico. a higher number of taxonomic studies on this genus are recommended, mainly for the states of puebla, veracruz, oaxaca, guerrero, morelos, and chiapas, where the keys are insufficient to identify them.
Mejora en el control en cascada para reactores tubulares
Hernández-Martínez, E.;Urrea, R.;Alvarez-Ramirez, J.;
Revista mexicana de ingeniería química , 2008,
Abstract: tubular reactors are difficult to operate due the intricate coupling between transport processes, nonlinear chemical kinetics, and their distributed nature. however, due to numerous industrial applications for chemical tubular reactors, the problem of monitoring and controlling them effectively is of great safety and economical importance. in this work, we introduce a new cascade control scheme based on three-temperature measurement distributed along the axial position of the tubular reactor with respect to a weighted average temperature (wav). the control configuration exploits the information provided by two additional temperatures sensor located at the feed and the output of the tubular reactor. the configuration with wav improves the behavior of the control scheme by enhancing the disturbance and parameter's uncertainty. numerical simulations are used to illustrate and compare the control performance.
Stabilized Conversion Efficiency and Dye-Sensitized Solar Cells from Beta vulgaris Pigment
Angel Ramon Hernández-Martínez,Miriam Estévez,Susana Vargas,Rogelio Rodríguez
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14024081
Abstract: Dye-Sensitized Solar Cells (DSSCs), based on TiO 2 and assembled using a dye from Beta vulgaris extract (BVE) with Tetraethylorthosilicate (TEOS), are reported. The dye BVE/TEOS increased its UV resistance, rendering an increase in the cell lifetime; the performance of these solar cells was compared to those prepared with BVE without TEOS. The efficiency η for the solar energy conversion was, for BVE and BVE/TEOS, of 0.89% ± 0.006% and 0.68% ± 0.006% with a current density Jsc of 2.71 ± 0.003 mA/cm 2 and 2.08 ± 0.003 mA/cm 2, respectively, using in both cases an irradiation of 100 mW/cm 2 at 25 °C. The efficiency of the BVE solar cell dropped from 0.9 ± 0.006 to 0.85 ± 0.006 after 72 h of operation, whereas for the BVE/TEOS, the efficiency remained practically constant in the same period of time.
La problemática en la taxonomía de los recursos genéticos de tejocote (Crataegus spp.) en México The problems in the taxonomy of the genetic resources of tejocote (Crataegus spp.) in Mexico
Carlos Alberto Nú?ez-Colín,Miguel ángel Hernández-Martínez
Revista mexicana de ciencias agrícolas , 2011,
Abstract: El género Crataegus (Rosaceae subtribu Pyrinae) es uno de los complejos taxonómicos más difíciles de tratar. Errores del pasado causan equivocaciones en la identificación de especies de este género, también existen nombres científicos que causan confusión en la determinación taxonómica. El presente trabajo tiene como objetivo describir la problemática, que existe en la taxonomía para este género y clarificar de la mejor manera la sistemática de los recursos genéticos del género Crataegus en México. Se plantea la posible identificación por zona geográfica el origen del tejocote (Crataegus spp.). El género Crataegus es complejo por sus distintos mecanismos reproductivos descritos como "el problema Crataegus". En México, sólo existen dos tratados taxonómicos, uno a principios del siglo XX y el otro enfocado al norte y parte del centro de México, por lo que es conveniente efectuar estudios taxonómicos sobre este género para los estados de Puebla, Veracruz, Oaxaca, Guerrero, Morelos y Chiapas, donde las claves existentes son insuficientes para la identificación de los especímenes. The genus Crataegus (Rosaceae subtribe Pyrinae) is one of the most difficult to treat taxonomic complexes. Furthermore, past mistakes are being repeated today by publications misclassifying specimens of the genus Crataegus, just as there are scientific names that cause confusion when identifying taxonomic identities. Due to this, the present study aims to describe the problems that exist in published taxonomies of the genus, mainly in Mexico, and thus try to clarify the best way to systematize of systematic of the genetic resources of the genus Crataegus. It also attempts to identify the geographical origin of tejocote (Crataegus spp.). The genus Crataegus presents reproductive complications known as "the Crataegus problem". Moreover, in Mexico, only two taxonomic treatments in this respect, one in the early twentieth century and the other only focused on the northern and part of central Mexico. A higher number of taxonomic studies on this genus are recommended, mainly for the states of Puebla, Veracruz, Oaxaca, Guerrero, Morelos, and Chiapas, where the keys are insufficient to identify them.
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