Browsing by Author "Valenzuela, P."

Now showing 1 - 9 of 9
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    Early child development inequalities and associated factors between public and private providers at metropolitan region in Chile
    (2016) Bedregal, Paula; Hernández, V.; Mingo, M. V.; Castañón Santibáñez, Carla Alejandra; Valenzuela, P.; Moore, R.; de la Cruz, R.; Castro, D.
    El desarrollo infantil temprano es un determinante de la salud física, mental y social de poblaciones. Conocer la situación de desarrollo de base, previo a la instalación de «Chile Crece Contigo», es clave para efectos de su evaluación. Objetivo: Comparar el desarrollo infantil temprano y factores asociados de preescolares del sector público y del sector privado de salud en la línea de base. Pacientes y método: Una muestra de 1.045 niños de la Región Metropolitana, de 30 a 58 meses, 52% hombres, 671 del sector público y 380 del privado de salud. Se evaluaron mediante el Inventario de Desarrollo Battelle-1 y una encuesta psicosocial en sus hogares aplicada al cuidador principal. Resultados: El 14,4% del sector privado y el 30,4% de la red pública tenían desarrollo alterado. No hubo diferencias en el área adaptativa entre ambos grupos (26,3% vs 29,2%). En las áreas cognitiva (8,8% vs 12,1%), personal-social (13,2% vs 32,5%), motriz (19,2% vs 35,3%) y comunicación (19,0% vs 36,8%) las diferencias fueron estadísticamente significativas. Mediante regresión logística se determinó que, independiente del nivel socioeconómico, son factores de riesgo: Apgar < 7 (OR: 5,4; IC 95%: 1,24-23,84), tener enfermedades crónicas de la infancia (OR: 1,3; IC 95%: 1,11-1,42); protector es: hogar con recursos para el aprendizaje y juego (OR: 0,8; IC 95%: 0,76-0,89). Conclusión: Estos resultados son un aporte al conocimiento de la situación del desarrollo infantil y para relevar su importancia para las políticas sociales en pediatría.
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    "Evaluation of the geotechnical behavior of Chilean volcanic soils as filter material for domestic water treatment"
    (PONTIFICIA UNIV CATOLICA CHILE, ESCUELA CONSTRUCCION CIVIL, 2011) Sanhueza, C.; Palma, J.; Valenzuela, P.; Araneda, O.; Calderon, K.
    Investigations carried out at Chile have determined that certain soils placed over the years as a product of the volcanic activity can be suitable for use as filter material in domestic wastewater purification. These soils have been studied by Universidad de Chile researchers, who have defined the main characteristics of the most important Chilean volcanic soils and, according to the properties studied (such as porosity, surface area and density, among others) have alleged that these materials exhibit water filter behaviour. As results of this research, first of all, the existing geotechnical information on Chilean volcanic soils has been complemented, such as hydraulic conductivity and, has been evaluating the influence design parameters, such as thickness of volcanic soil layers and the application rate of wastewater, in the purification of domestic wastewater.
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    Mechanical and microstructural properties of broadband anti-reflective TiO2/SiO2 coatings for photovoltaic applications fabricated by magnetron sputtering
    (2021) Zambrano, D. F.; Villarroel, R.; Espinoza-Gonzalez, R.; Carvajal, N.; Rosenkranz, A.; Montano-Figueroa, A. G.; Arellano-Jimenez, M. J.; Quevedo-Lopez, M.; Valenzuela, P.; Gacitua, W.
    Anti-reflective coatings are used in photovoltaic systems to minimize reflectance thus optimizing efficiency. Besides excellent optical properties, these coatings need to provide good mechanical properties due to hostile environmental conditions. Therefore, this study aims at designing anti-reflective coatings based upon multi layers of TiO2 and SiO2 by magnetron sputtering on glass and silicon substrates at room temperature. Afterwards, these coatings were thermally annealed at 400, 500 and 600 degrees C to study the influence of such treatment on their optical and mechanical properties. Samples prepared at room temperature and annealed at 400 degrees C showed an optimized reflectance of about 2%. Advanced materials characterization techniques were used to elucidate the microstructural evolution of the multi-layers. The multi-layers annealed at 400 degrees C demonstrated a dense and smoothly packed microstructure with homogenous grains (50 nm in size), with a phase transformation from amorphous to anatase. In addition, exposure and damage of the glass substrate were detected for elevated temperatures (500 and 600 degrees C), thus increasing the reflectance. Nanoindentation revealed an improved hardness, elasticity, and resistance against plastic deformation for the sample annealed at 400 degrees C. Consequently, anti reflective coatings with post-annealing treatment at 400 degrees C, unify two complementary aspects such as improved mechanical properties (extended durability) and enhanced collection abilities over a broader wavelength range (increased efficiency).
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    Modelo computacional interactivo, semi-automatizado y de código abierto aplicado a la vigilancia de virus respiratorios
    (2020) Reyes Zaldivar, Felipe Tomás; Ferrés, Marcela; Vial, P.; Vollrath, V.; Camponovo, R.; Montecinos, L.; Hirsch Birn, Tamara; Valenzuela, P.; Perret Pérez, Cecilia
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    Poly(amides) and poly(imides) containing silicon and germanium in the main chain : synthesis, characterization and thermal studies
    (2006) Tagle Domínguez, Luis Hernán; Terraza Inostroza, Claudio; Leiva Campusano, Ángel; Valenzuela, P.
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    Polymerization by phase transfer catalysis. 25. Synthesis of polycarbonates and polythiocarbonates derived from diphenols containing germanium and silicon in the main chain
    (2000) Tagle Domínguez, Luis Hernán; Vega, J. C.; Díaz Alzamora, Fernando Raúl; Radić Foschino, Deodato D.; Gargallo Gómez, Ligia Teresita; Valenzuela, P.
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    Synthesis and characterization of poly(esters) derived from diacids and diphenols containing silicon and germanium
    (2003) Tagle Domínguez, Luis Hernán; Díaz Alzamora, Fernando Raúl; Vega, J. C.; Valenzuela, P.
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    The paradoxical response of growth hormone (GH) to thyrotropin-releasing hormone (TRH) in constitutionally tall children involves a cholinergic pathway
    (1989) Arteaga U., Eugenio; Valenzuela, P.; Cattani Ortega, Andreina; Valle de la Cortina, María Angélica del
    To investigate whether or not a cholinergic pathway is involved in the paradoxical response of GH to TRH in constitutionally tall children, we studied 8 healthy prepubertal children aged $4^{2}/{_{_{12}}} - 7^{10}/{_{_{12}}} {? yr}$, whose heights were over the 95th percentile of the NCHS tables. We defined as ?paradoxical? a GH increment greater than 5 ng/ml in response to TRH. Five out of 8 children showed a paradoxical response of GH to TRH (mean GH peak after TRH of 10.7 ? 1.1 ng/ml). Pretreatment with atropine (0.01 mg/kg IM 30 min prior to the TRH administration) abolished the TRH induced GH rise (peak GH after TRH of 1.5 ? 1.0 ng/ml, p < 0.01) but did not modify the TSH response (peak TSH after TRH: basal conditions 8.7 ? 0.8 ?U/ml, post atropine: 9.5 ? 1.4 ?U/ml, p > 0.05). Our results demonstrate that a cholinergic pathway is involved in the paradoxical response of GH to TRH in constitutionally tall children.