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Search Results: 1 - 10 of 31827 matches for " Ricardo Guillermo álvarez "
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Differential Deterrent Activity of Natural Products Isolated from Allophylus edulis (Sapindaceae)  [PDF]
Martina Díaz, Lucía Castillo, Carmen E. Díaz, Ricardo Guillermo álvarez, Azucena González-Coloma, Carmen Rossini
Advances in Biological Chemistry (ABC) , 2014, DOI: 10.4236/abc.2014.42021
Abstract: The phytochemical study of Uruguayan specimens of Allophylus edulis (Sapindaceae) yielded the isolation of various natural products being some of them reported for the first time in this species. Although most of them are ubiquitous in the plant kingdom, some revealed in this study to have anti insect properties. Two sesquiterpenes (6,7-Epoxicaryophyllene and spathulenol), two phytosterols (sitosterone and sitosterol), a pentacyclic triterpene (lupeol) and a clerodane diterpene were isolated. 6,7-Epoxycaryophyllene, lupeol and sitosterol showed to be deterrent against the aphid Myzus persicae and the coleopteran Epilachna paenulata. Moreover, the crude ethanolic extract of twigs of A. edulis showed to be deterrent against both insect species being some of its fractions also active against another aphid, Rhopalosiphum padi. Various active compounds against different insect models have been isolated from the twigs extract of A. edulis. The results evidenced synergic as well as antagonistic effects in the mixture, summed to differential activity against the insects, a desirable attribute when developing botanical pesticides.
Modified Maximum Likelihood Estimation in Autoregressive Processes with Generalized Exponential Innovations  [PDF]
Bernardo Lagos-álvarez, Guillermo Ferreira, Emilio Porcu
Open Journal of Statistics (OJS) , 2014, DOI: 10.4236/ojs.2014.48058
Abstract: We consider a time series following a simple linear regression with first-order autoregressive errors belonging to the class of heavy-tailed distributions. The proposed model provides a useful generalization of the symmetrical linear regression models with independent error, since the error distribution covers both correlated innovations following a Generalized Exponential distribution. Furthermore, we derive the modified maximum likelihood (MML) estimators as an efficient alternative for estimating model parameters. Finally, we investigate the asymptotic properties of the proposed estimators. Our findings are also illustrated through a simulation study.
Apuntes para la historia de la anestesiología en el Perú. Desde la época precolombina hasta 1947.
Ricardo álvarez
Actas Peruanas de Anestesiología , 2011,
Abstract: Hoy en día es imposible imaginar un procedimiento quirúrgico, por más simple que éste sea, sin la invalorable ayuda de la analgesia y/o anestesia. Sin embargo, durante siglos no existieron estos medios tecnológicos, y ése fue uno de los factores que impidieron el desarrollo de la cirugía. El objetivo de este artículo es relatar el progreso y los principales hitos ocurridos desde la época precolombina hasta 1947, en que se cumplieron los primeros cien a os de la introducción de la anestesiología en el Perú.
La encuesta de opinión estudiantil: un sitema de información para la evaluación por competencias de la actividad docente
Galavis,Sowiesky; álvarez,Guillermo;
Revista de la Facultad de Ingeniería Universidad Central de Venezuela , 2010,
Abstract: the thematic guideline in this case is the following: the competence approach is based on the concept that people learn through their activity within a cultural context. feedback allows people to be aware of their own performance. students are observers par excellence of in-the-classroom performance. the eoe programme allows for the feedback process to take place by gathering and communicating to all parties involved the findings of the students about in-the-classroom teaching. this instrument is not, however, intended to be an instrument for evaluating the teaching personnel, as it only reflects reality from the students? view. in turn, it hopefully is a useful tool so that the different actors in the learning process, through a process of gaining awareness on how their strengths and weaknesses are perceived, can better manage a positive change and, at the same time, count on the necessary support from the institution. we conclude that the student opinion poll (eoe) has to be considered an information system that samples in a methodical and regular manner the students? perception of the academic performance that influences their professional training, processes this information, and keeps it in store for users in an easy-to-interpret format, as, for example, historic series expressed through graphics and/or numerical charts. at the same time, this information should be available for particular decision-making processes, i.e. as additional input for the self-evaluations of the teaching personnel, for students when having to decide on their academic workload, and for the institution when reformulating growth and improvement plans.
La piratería americana y su incidencia en el Nuevo Reino de Granada, siglos XVI-XVIII: un ensayo bibliográfico
Leonardo Guillermo Moreno álvarez
Fronteras de la Historia , 2007,
Abstract: El presente ensayo surge de la necesidad de clarificar el rol de la piratería en la historia de las colonias hispánicas en América, que es comúnmente pasado por alto debido no sólo a los lugares comunes del folclor popular sobre los piratas, sino a la dificultad de enmarcar su desarrollo como problema histórico en una única categoría, sea ésta económica, política o sociológica; por lo cual las acciones de los piratas y corsarios se deben pensar siempre a partir de un contexto global. A partir de esto se elaboran ciertas precisiones teóricas y una revisión de los episodios más emblemáticos de la piratería en la costa caribe a de la Nueva Granada, con fundamento, principalmente, en el estudio de fuentes secundarias
The Role of Everolimus in the Treatment of Breast Cancer  [PDF]
José Pablo Leone, Ricardo H. álvarez
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.47136
Abstract: The development of resistance to chemotherapy, endocrine therapy and anti HER2 agents in breast cancer is an important and common problem that impacts in the management of patients, particularly in the metastatic setting. This resistance has been explained in part by the activation of signal transduction pathways, including the PI3K/AKT/mTOR. The blockade with mTOR inhibitors such as everolimus is a new target agent for therapy that attempts to enhance treatment efficacy and restore tumor sensitivity. In this review article, we present the data about the use of everolimus for the treatment of breast cancer in all tumor phenotypes. Future studies that evaluate biomarkers for treatment response are needed to identify the specific populations that have the highest benefit of this new targeted therapy.

Los Amphisbaenidae en Paraguay, listado geográfico
Montero, Ricardo,Terol, Guillermo
Cuadernos de Herpetología , 1999,
Abstract:
Estructura y temporalidad urbana de las ciudades intermedias en México
álvarez de la Torre, Guillermo;
Frontera norte , 2011,
Abstract: the internal structure of cities has been examined through various disciplines such as economic spatial models, ecological structures and land use. this paper seeks to study centrality in urban structure models for medium-sized mexican cities through the spatial analysis of population density, population age structure and housing in 32 mexican cities. quantitative urban structure models use distance to the central business district as a basic aspect for determining the behavior of certain phenomena. this study shows that the historical period to which urban space belongs enables one to identify consistent spatial patterns in the structure of intermediate mexican cities.
Estructura y temporalidad urbana de las ciudades intermedias en México
Guillermo álvarez de la Torre
Frontera norte , 2011,
Abstract: Este trabajo exploratorio pretende aplicar y estudiar esquemas espaciales monocéntricos de ciudades a partir del análisis espacial sobre el gradiente de densidad, estructura de edad de la población y tenencia de la vivienda en 32 ciudades intermedias mexicanas. Los modelos cuantitativos de estructura urbana toman como referencia la distancia al centro de negocios de la ciudad como un elemento, determinante en el comportamiento de ciertos fenómenos. En el presente estudio vemos cómo el factor del período histórico al que pertenece el espacio urbano permite encontrar patrones espaciales consistentes en la estructura de las ciudades intermedias mexicanas.
Diez a os de regulación de los servicios públicos domiciliarios en Colombia: lo bueno, lo malo y lo feo de un modelo mestizo
Luis Guillermo Vélez álvarez
Lecturas de Economía , 2006,
Abstract: La ley 142 de 1994, que estableció el régimen de los servicios públicos domiciliarios en Colombia, llevó a la constitución de un modelo mixto de prestación de servicios públicos en el país. Después de más de 10 a os de esta ley, el siguiente artículo indaga sobre la sostenibilidad y perdurabilidad del actual modelo. Para ello, el análisis se realiza desde cuatro perspectivas: la propiedad, la financiación, la competencia y la regulación. El autor afirma que dicha sostenibilidad dependerá de variables como la voluntad política del Estado, el desempe o de las empresas estatales y los incentivos para que el sector privado mantenga y amplíe sus inversiones.
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