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Search Results: 1 - 10 of 472805 matches for " Miguel A. Parada "
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Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
Parada,Miguel A.; Lahsen,Alfredo; Palacios,Carlos;
Revista geológica de Chile , 2001, DOI: 10.4067/S0716-02082001000100002
Abstract: eighteen new radiometric ages (fourteen 40ar-39ar, four k-ar), combined with previously published ages, confirm the existence of three main extensional back-arc volcanic events, previously defined by stratigraphic relationships, in chilean patagonia (aysén region). these three events developed during the middle jurassic -early cretaceous (160-130 ma). cretaceous (114-75 ma), and eocene (55-46 ma). based on distinct geochemical data and sr-nd isotopic characteristics of the back-arc volcanic rocks collected north and south of 46°30's, two mesozoic-eocene magmatic domains are recognized: northern magmatic domain (nmd) and southern magmatic domain (smd). most analyzed basalts and intermediate volcanic rocks of the nmd have alkaline affinities and depleted to slightly depleted sr-nd isotopic values similar to those derived from an asthenosphere-dominated source. the smd mafic volcanic rocks have a subalkaline character and more enriched sr-nd isotopic signatures, comparable to those derived from a lithospheric source. the felsic volcanic rocks of the smd have lower end values and slightly higher initial 87sr/86sr ratios than the nmd felsic rocks, suggesting a larger crustal contribution in the magma sources. the geochemical and isotopic distinction between nmd and smd felsic rocks could be influenced by the presence of paleozoic metamorphic rocks as basement of the volcanic rocks of the smd. moreover, the compositional distinction between basalts of both domains may correspond to differences in magnitude of extension, the nmd being the one where the extension would have been greater and, consequently, the lithosphere thinner
Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
Miguel A. Parada,Alfredo Lahsen,Carlos Palacios
Revista geológica de Chile , 2001,
Abstract: Eighteen new radiometric ages (fourteen 40Ar-39Ar, four K-Ar), combined with previously published ages, confirm the existence of three main extensional back-arc volcanic events, previously defined by stratigraphic relationships, in Chilean Patagonia (Aysén region). These three events developed during the Middle Jurassic -Early Cretaceous (160-130 Ma). Cretaceous (114-75 Ma), and Eocene (55-46 Ma). Based on distinct geochemical data and Sr-Nd isotopic characteristics of the back-arc volcanic rocks collected north and south of 46°30'S, two Mesozoic-Eocene magmatic domains are recognized: Northern Magmatic Domain (NMD) and Southern Magmatic Domain (SMD). Most analyzed basalts and intermediate volcanic rocks of the NMD have alkaline affinities and depleted to slightly depleted Sr-Nd isotopic values similar to those derived from an asthenosphere-dominated source. The SMD mafic volcanic rocks have a subalkaline character and more enriched Sr-Nd isotopic signatures, comparable to those derived from a lithospheric source. The felsic volcanic rocks of the SMD have lower eNd values and slightly higher initial 87Sr/86Sr ratios than the NMD felsic rocks, suggesting a larger crustal contribution in the magma sources. The geochemical and isotopic distinction between NMD and SMD felsic rocks could be influenced by the presence of Paleozoic metamorphic rocks as basement of the volcanic rocks of the SMD. Moreover, the compositional distinction between basalts of both domains may correspond to differences in magnitude of extension, the NMD being the one where the extension would have been greater and, consequently, the lithosphere thinner Edades y geoquímica de las rocas volcánicas del trasarco del Mesozoico-Eoceno en la región de Aysén de los Andes patagónicos, Chile. Diez y ocho nuevas edades radiométricas (catorce 40Ar-39Ar, cuatro K-Ar) junto con las ya publicadas confirman la existencia de tres eventos volcánicos (previamente definidos por relaciones estratigráficas) en la Patagonia chilena (Región de Aysén) durante el intervalo Mesozoico-Eoceno: Jurásico Medio-Cretácico temprano (160-130 Ma), Cretácico (114-75 Ma) y Eoceno (55-46 Ma). Sobre la base de las características geoquímicas e isotópicas de Sr y Nd de las rocas volcánicas estudiadas, se pueden reconocer dos dominios magmáticos Mesozoico-Eoceno: Dominio Magmático Norte (DMN) y Dominio Magmático Sur (DMS). Los basaltos y rocas intermedias del DMN tienen afinidades alcalinas y valores isotópicos de Sr-Nd deprimidos a moderadamente deprimidos similares a aquellos derivados de una fuente dominada por material as
Economic and Emotional Rationality: An Application to Wealth Concentration  [PDF]
Jose Rigoberto Parada-Daza, Miguel Ignacio Parada-Contzen
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.34040
Abstract:

This Paper presents a theoretical outline regarding the Emotional Well-being (EW) function as an extension of the economic utility function. EW includes habitual factors that are always present in everyday decision making. Firstly, an analytical-mathematical conceptualization of EW is carried out, followed by a study of the concept of emotional security, in order to define a new idea of emotional rationality as a complement to economic rationality. An explanation is put forth, as an application, of the concentration of wealth phenomenon according to the focus on economic and emotional rationality. The conclusion is that EW is a theoretical approach which can clarify the understanding of the decision making process in economics activities.

Pythagoras and the Creation of Knowledge  [PDF]
Jose R. Parada-Daza, Miguel I. Parada-Contzen
Open Journal of Philosophy (OJPP) , 2014, DOI: 10.4236/ojpp.2014.41010
Abstract:

In this paper, an approach to Pythagoras’ Theorem is presented within the historical context in which it was developed and from the underlying intellectual outline of the Pythagorean School. This was analyzed from a rationalism standpoint. An experiment is presented to the reader so that they, through direct observation, can analyze Pythagoras’ Theorem and its relation to the creation of knowledge. The theory of knowledge conceptualization is used.

Carbon isotopes and the K-T boundary in Argentina and Chile
Ferreira Valderez P.,Sial Alcides N.,Parada Miguel A.,Toselli Alejandro J.
Anais da Academia Brasileira de Ciências , 2000,
Abstract:
Hepatotoxicity in Mice of a Novel Anti-parasite Drug Candidate Hydroxymethylnitrofurazone: A Comparison with Benznidazole
Carolina Davies,Nilay Dey,Olga Sanchez Negrette,Luis Antonio Parada,Miguel A. Basombrio,Nisha Jain Garg
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0003231
Abstract: Background Treatment of Chagas disease, caused by Trypanosoma cruzi, relies on nifurtimox and benznidazole (BZL), which present side effects in adult patients, and natural resistance in some parasite strains. Hydroxymethylnitrofurazone (NFOH) is a new drug candidate with demonstrated trypanocidal activity; however, its safety is not known. Methods HepG2 cells dose response to NFOH and BZL (5–100 μM) was assessed by measurement of ROS, DNA damage and survival. Swiss mice were treated with NFOH or BZL for short-term (ST, 21 d) or long-term (LT, 60 d) periods. Sera levels of cellular injury markers, liver inflammatory and oxidative stress, and fibrotic remodeling were monitored. Results HepG2 cells exhibited mild stress, evidenced by increased ROS and DNA damage, in response to NFOH, while BZL at 100 μM concentration induced >33% cell death in 24 h. In mice, NFOH ST treatment resulted in mild-to-no increase in the liver injury biomarkers (GOT, GPT), and liver levels of inflammatory (myeloperoxidase, TNF-α), oxidative (lipid peroxides) and nitrosative (3-nitrotyrosine) stress. These stress responses in NFOH LT treated mice were normalized to control levels. BZL-treated mice exhibited a >5-fold increase in GOT, GPT and TNF-α (LT) and a 20–40% increase in liver levels of MPO activity (ST and LT) in comparison with NFOH-treated mice. The liver inflammatory infiltrate was noted in the order of BZL>vehicle≥NFOH and BZL>NFOH≥vehicle, respectively, after ST and LT treatments. Liver fibrotic remodeling, identified after ST treatment, was in the order of BZL>vehicle>NFOH; lipid deposits, indicative of mitochondrial dysfunction and in the order of NFOH>vehicle>BZL were evidenced after LT treatment. Conclusions NFOH induces mild ST hepatotoxicity that is normalized during LT treatment in mice. Our results suggest that additional studies to determine the efficacy and toxicity of NFOH are warranted.
Toxicología subcrónica de infusión de Chenopodium ambrosioides (epazote) por administración oral en ratones NIH Subchronic toxicology of Chenopodium ambrosioides (epazote) infusion orally administered to NIH mice
Miguel ángel Moreno Mendoza,Elvert Antonio Parada Palacios,José Guillermo Mejía Valencia,Paul Augusto Espinoza Madrid
Revista Cubana de Plantas Medicinales , 2013,
Abstract: Introducción: las plantas medicinales constituyen una valiosa alternativa terapéutica y su validación científica es una necesidad. Objetivo: identificar los posibles efectos tóxicos producidos por la infusión de Chenopodium ambrosioides L. (Chenopodiaceae) sobre el modelo biológico utilizado. Métodos: para determinar la toxicidad subcrónica de la infusión se emplearon ratones albinos suizos NIH de los 2 sexos, a los que se les administró por vía oral infusiones de la especie estudiada a concentraciones de 32, 64 y 134 mg/mL por 90 días. Al mismo tiempo se realizaron observaciones clínicas diarias con el fin de identificar algún efecto tóxico posadministración de la sustancia. Después fueron sacrificados para realizar los exámenes hematológicos (hematocrito, hemoglobina, glóbulos rojos, glóbulos blancos, neutrófilos y linfocitos) y bioquímicos (alanino aminotransferasa y creatinina), así como estudios macroscópicos e histológicos de los órganos internos (ri ón, hígado, pulmón e intestino). Resultados: se encontró que la infusión de Chenopodium ambrosioides a las dosis administradas no causó efectos determinantemente significativos en los parámetros toxicológicos, en el peso corporal, en hematología y química sanguínea, al igual que tampoco provocó alteraciones anatomopatológicas sobre los órganos y tejidos evaluados. Conclusiones: la infusión de Chenopodium ambrosioides bajo estas condiciones experimentales no presentó actividad tóxica. Introduction: medicinal plants represent a valuable therapeutic alternative and their scientific validation is a must. Objectives: to determine the possible toxic effects produced by the infusion of Chenopodium ambrosioides L. (Chenopodiaceae) on the used biological model. Methods: to determine the subchronic toxicity of the infusion, NIH Swiss albino mice of both sexes were used, to which infusions from the tested species, at concentrations of 32, 64, and 134 mg/mL , were orally administered for 90 days. At the same time, daily clinical observations were performed in order to identify any toxic post-dose administration. Afterwards, they were sacrificed for conduction of hematological tests (hematocrit, hemoglobin, red blood cells, white cells, neutrophils and lymphocytes) and biochemical (alanine aminotransferase and creatinine) and macroscopic and histological studies of the internal organs (kidney, liver, lung and intestine.). Results: the infusion of Chenopodium ambrosioides at the tested doses caused neither decisively significant effects on the toxicological parameters, body weight, hematology and blood chemistry no
La retórica del miedo en la prensa bogotana de 1834
Parada García,Gilberto Enrique;
Historia Crítica , 2008,
Abstract: this article analyzes the discourse of the press in bogotá during the 1830s. the aim of this discourse was to publicly project the contours of chaos in order to back a new version of the socio-political order. the article focuses on the development and use of the rhetorical apparatus of fear that anteceded and paved the way for the promulgation of a new, bourgeois-liberal inspired legal ideology. it also demonstrates, from this discourse, how the bogotá elite understood the identity of the city?s popular sectors at the same time that it ratifed its own identity as the dominant group. the literature that frames this study is the social history of the legal world. in the context of new granada in the frst half of the nineteenth century, this was a world that experienced the initial moments of modernity refected on a discursive plane.
La retórica del miedo en la prensa bogotana de 1834.
Gilberto Enrique Parada García.
Historia Crítica , 2008,
Abstract: This article analyzes the discourse of the press in Bogotá during the 1830s. The aim of this discourse was to publicly project the contours of chaos in order to back a new version of the socio-political order. The article focuses on the development and use of the rhetorical apparatus of fear that anteceded and paved the way for the promulgation of a new, bourgeois-liberal inspired legal ideology. It also demonstrates, from this discourse, how the Bogotá elite understood the identity of the city’s popular sectors at the same time that it ratifed its own identity as the dominant group. The literature that frames this study is the social history of the legal world. In the context of New Granada in the frst half of the nineteenth century, this was a world that experienced the initial moments of modernity refected on a discursive plane.
Jack Goody.Capitalismo y modernidad: el gran debate.Barcelona: Crítica, 2005. 241 páginas.
Parada García Gilberto Enrique
Anuario Colombiano de Historia Social y de la Cultura , 2007,
Abstract:
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