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Search Results: 1 - 10 of 206554 matches for " Alejandro Dávila Flores "
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Los clusters industriales del noreste de México (1993-2003): Perspectivas de desarrollo en el marco de una mayor integración económica con Texas
Dávila Flores, Alejandro;
Región y sociedad , 2008,
Abstract: using the methodology developed by feser and bergman (2000), the industrial clusters of northeast mexico are identified. the economic performance of clusters between 1993 and 2003 is analyzed using regional economic analysis techniques. finally, the opportunities of cluster development are explored within the framework of a greater commercial integration with the state of texas.
México: concentración y localización del empleo manufacturero, 1980-1998
Alejandro Dávila Flores
Economía Mexicana , 2004,
Abstract: Mediante la aplicación de una variante del índice de Gini, se mide la evolución de la concentración geográfica del empleo manufacturero en México. Inicialmente se define el procedimiento para derivar, de una función de distribución regional del empleo manufacturero, la curva de Lorenz. Posteriormente, se calculan los valores del coeficiente de Gini para cada una de las 54 ramas de actividad económica que integran la industria manufacturera. Mediante la utilización de técnicas estadísticas de agrupamiento (cluster analysis), se identifican los niveles de concentración del empleo en cada rama. Así mismo, se calculan los índices de concentración del empleo manufacturero y los coeficientes de localización por rama, para cada una de las 32 entidades federativas que integran la república mexicana. Los datos se agrupan en regiones más amplias, con el propósito de identificar los patrones sectoriales y regionales de localización de la manufactura y su evolución entre 1980 y 1998.
Los clusters industriales del noreste de México (1993-2003). Perspectivas de desarrollo en el marco de una mayor integración económica con Texas
Alejandro Dávila Flores
Región y sociedad , 2008,
Abstract: Con la metodología de Feser y Bergman (2000), se identifican los clusters industriales del noreste de México. Con técnicas de análisis económico regional, se evalúa su desempe o económico de 1993 a 2003. Finalmente, se exploran sus oportunidades de desarrollo en el marco de una mayor integración comercial con el estado de Texas.
Experimental and quantum chemical studies of a novel synthetic prenylated chalcone
José C Espinoza-Hicks, Alejandro A Camacho-Dávila, Norma R Flores-Holguín, Guadalupe V Nevárez-Moorillón, Daniel Glossman-Mitnik, Luz M Rodríguez-Valdez
Chemistry Central Journal , 2013, DOI: 10.1186/1752-153x-7-17
Abstract: A novel substituted chalcone has been synthetized. In order to identify the functional groups present in the new synthesized compound and confirm its chemical structure, experimental and theoretical 1H-NMR and 13C-NMR spectra were analyzed. The theoretical molecular structure and NMR spectra were calculated at both the Hartree-Fock and Density Functional (meta: TPSS; hybrid: B3LYP and PBE1PBE; hybrid meta GGA: M05-2X and M06-2X) levels of theory in combination with a 6-311++G(d,p) basis set. The structural parameters showed that the best method for geometry optimization was DFT:M06-2X/6-311++G(d,p), whereas the calculated bond angles and bond distances match experimental values of similar chalcone derivatives. The NMR calculations were carried out using the Gauge-Independent Atomic Orbital (GIAO) formalism in a DFT:M06-2X/6-311++G(d,p) optimized geometry.Considering all HF and DFT methods with GIAO calculations, TPSS and PBE1PBE were the most accurate methods used for calculation of 1H-NMR and 13C-NMR chemical shifts, which was almost similar to the B3LYP functional, followed in order by HF, M05-2X and M06-2X methods. All calculations were done using the Gaussian 09 software package. Theoretical calculations can be used to predict and confirm the structure of substituted chalcones with good correlation with the experimental data.Chalcones are ubiquitous substances found in a diversity of plants. They are precursors to other natural products, such as flavonoids, which have reported a wide range of biological activities such as antioxidant, antibacterial, antitumoral among others [1]. Due to the importance of these compounds, diverse studies on synthesis and biological activities of molecules containing the chalcone ring system, have been reported recently [2]. The prenyloxychalcones are important derivatives of chalcones, which contain a prenyl-type side chain with different length, including 2,2-dimethylallyl, geranyl or farnesyl chains; these compounds have shown i
Pyrene-Fullerene C60 Dyads as Light-Harvesting Antennas
Gerardo Zaragoza-Galán,Jesús Ortíz-Palacios,Bianca X. Valderrama,Alejandro A. Camacho-Dávila,David Chávez-Flores,Víctor H. Ramos-Sánchez,Ernesto Rivera
Molecules , 2014, DOI: 10.3390/molecules19010352
Abstract: A series of pyrene -fullerene C 60 dyads bearing pyrene units (PyFC 12, PyFPy, Py 2FC 12 and PyFN) were synthesized and characterized. Their optical properties were studied by absorption and fluorescence spectroscopies. Dyads were designed in this way because the pyrene moeities act as light-harvesting molecules and are able to produce “monomer” (PyFC 12) or excimer emission (PyFPy, Py 2FC 12 and PyFN). The fluorescence spectra of the dyads exhibited a significant decrease in the amount of pyrene monomer and excimer emission, without the appearance of a new emission band due to fullerene C 60. The pyrene fluorescence quenching was found to be almost quantitative, ranging between 96%–99% depending on the construct, which is an indication that energy transfer occurred from one of the excited pyrene species to the fullerene C 60.
Geothermal Diatoms: Seasonal Variability in the El Tatio Geothermal Field (Altiplano, Chile)  [PDF]
Alejandro Angel, Irma Vila, Carolina Díaz, Ximena Molina, Paola Sepúlveda
Advances in Microbiology (AiM) , 2018, DOI: 10.4236/aim.2018.83015
Abstract: Diatom floras were examined in a high-altitude geothermal field, 4200 - 4500 m (29°19'S 68°W'), located in the Central Andean dry Puna ecoregion or southern Altiplano. These locations include hostile environments subjecting living organisms to extreme conditions. The aim of the present study was to investigate the spatial patterns and describe the response of diatom assemblages to differences in physical and chemical variables. Different shallow (<10 cm) aquatic systems with variable chemical and physical conditions (fumaroles, freshwater-saline rivers and swamps) were studied seasonally during 2011-2012. The conductivity exhibited high variability (360 to 18340 μS cm-1) among the systems studied, temperature was lower in rivers and swamps (6.8°C - 10°C) and high in fumaroles stations (30°C - 37.5°C), and pH was lower in fumaroles than freshwater systems (3.25 to 8.97). Statistical analyses suggest that the diatoms cluster into three major groups. The most common taxa include: Achnanthidium exiguum (Grunow) Czarnecki, Cocconeis placentula var. lineata (Ehrenberg) Van Heurck, Eolimna minima (Grunow) Lange-Bertalot, Staurosirella pinnata (Ehrenberg) Williams and Round, Navicula gregaria Donkin, Nitzschia inconspicua Grunow, Nitzschia palea (Kützing) Smith, Nitzschia perminuta (Grunow) Peragallo, and Planothidium lanceolatum (Brébisson ex Kützing) Lange-Bertalot. As expected, the 20 to 200 μm-size fraction contained the highest numbers of diatom taxa (53 species), although an unexpectedly high number (47 species) were also found in the smaller 5 to 20 μm-size fraction, more associated to fumaroles and saline systems. The 180 to 2000 μm size fraction contained only two species, including rosette-forming diatom Ulnaria ulna (Nitzsch) Compère, and the unicellular species Surirella chilensis Janisch, both species exclusively reported in freshwater systems. Canonical correspondence analysis (CCA) and Monte Carlo permutation tests showed clear correlations between species, conductivity, TP (total phosphorous), NO3- , HO3- , Mg2+, temperature and dissolved oxygen (DO). The gradient of ionic composition values explaining most variation in diatom assemblages ranged from waters dominated by Ca2+ and SO4- to waters with higher proportions of Na+, K+,
Los indígenas en ciudades de México: el caso de los mazahuas, otomíes, triquis, zapotecos y mayas
Patricia Noemí Vargas Becerra,Julia Isabel Flores Dávila
Papeles de población , 2002,
Abstract: El presente trabajo sintetiza los resultados de la investigación Perfiles de los Indígenas en Ciudades de México dise ada para conocer las características demográficas, sus condiciones de vida, la persistencia cultural y la cultura de la identidad de los mazahuas, otomíes, triquis, mayas y zapotecos en tres configuraciones urbanas distintas: la gran metrópoli, la ciudad de México y su zona metropolitana; zonas industriales como el corredor industrial Minatitlán-Veracruz, y una ciudad turística: Cancún, Quintana Roo.
Factores de riesgo asociados con la preeclampsia
D Alejandro,Garrán Teppa,José Terán Dávila
Revista de Obstetricia y Ginecología de Venezuela , 2001,
Actualidad en el tratamiento de la osteoporosis posmenopáusica
José Terán Dávila,Alejandro D. Teppa Garrán
Revista de Obstetricia y Ginecología de Venezuela , 2003,
Macroadenoma prolactinosecretante y tratamiento con cabergolina. Caso clínico
Terán Dávila,José; Teppa Garrán,Alejandro;
Revista de Obstetricia y Ginecología de Venezuela , 2003,
Abstract: we present the first national experience in the treatment of macroprolactinoma with cabergoline and revision of the existent information in the literature.
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