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Search Results: 1 - 10 of 476408 matches for " Pe?a-Corona Marco Polo "
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Del tabaco al uso de otras drogas: el uso temprano de tabaco aumenta la probabilidad de usar otras drogas?
Medina-Mora Ma. Elena,Pea-Corona Marco Polo,Cravioto Patricia,Villatoro Jorge
Salud Pública de México , 2002,
Abstract: Objetivo. Analizar la probabilidad de abuso de sustancias en relación con la edad de inicio del consumo de tabaco. Material y métodos. Los datos provienen de la Encuesta Nacional de Adicciones (1998) realizada en población urbana. Resultados. La edad de mayor riesgo para experimentar con sustancias es entre los 15 y los 19 a os. Solamente en 5.6% de los usuarios de drogas y 13% de los que han consumido alcohol, el uso del tabaco no ocurrió primero. La probabilidad de beber en forma consuetudinaria y de presentar dependencia es mayor cuando la edad de inicio es temprana y disminuye en la medida en que se retrasa la edad de inicio. La experimentación con drogas, el continuar usándolas y el poliuso son más frecuentes entre quienes se iniciaron antes de los 15 a os. Conclusiones. El inicio temprano en el consumo de tabaco incrementa la probabilidad de uso y abuso de sustancias.
Del tabaco al uso de otras drogas: ?el uso temprano de tabaco aumenta la probabilidad de usar otras drogas?
Medina-Mora,Ma. Elena; Pea-Corona,Marco Polo; Cravioto,Patricia; Villatoro,Jorge; Kuri,Pablo;
Salud Pública de México , 2002, DOI: 10.1590/S0036-36342002000700016
Abstract: objective. to assess the likelihood of substance abuse predicted by age of first exposure to tobacco. material and methods. data from the 1998 national household survey on addictions in urban areas were analyzed. results. the age period of greater likelihood of drug experimentation is between 15 and 19 years; only 5.6% of drug users and 13% of alcohol beverage drinkers reported having experimented with drugs before trying tobacco. the probability of heavy drinking and dependence was higher at early ages of first exposure to tobacco and decreased with increasing age. experimentation with drugs, continued use, and multiple drug use, are more frequent among smokers who started before 15 years of age. conclusions. early tobacco use increases the likelihood of substance abuse.
Curvas anamórficas de índice de sitio para plantaciones de Pinus caribaea Morelet var. caribaea Barret y Golfari de la empresa forestal integral macurije (EFI) en la provincia de Pinar del Río, Cuba
Barrero-Medel, Héctor;Mothe, Frédéric;Nepveu, Gérard;álvarez-Lazo, Daniel;García-Corona, Ilya;Guera, Mariel;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2011, DOI: 10.5154/r.rchscfa.2010.06.035
Abstract: in this work we selected the best model for obtaining anamorphic site index curves for pinus caribaea morelet var. caribaea barret and golfari stands belonging to the macurije integral forest company, located in the municipalities of guane and mantua in the province of pinar del rio, cuba. we used data recorded from 14 permanent plots established in the year 2006 with four consecutive measurements taken throughout the different basic forest production units, 256 temporary lots randomly distributed throughout the enterprise area and the forest inventory carried out by the company in 2002-2003. the anamorphic-based site index curve system was constructed using the nested regression method applied by bailey and clutter (1976) and described by alder (1980) as a method of hierarchical regression with a common slope estimator. the model fitted dominant height (ho)-age data, and six site indices were derived for 13, 16, 19, 22, 25 and 28 m at 35 years old. in addition, the equation for determining the site index was obtained.
Efecto de la contaminación ambiental sobre las consultas por infecciones respiratorias en ni os de la Ciudad de México
TéLLES-ROJO MARTHA MARíA,ROMIEU ISABELLE,POLO-PEA MARCO,RUIZ-VELASCO SILVIA
Salud Pública de México , 1997,
Abstract: Objetivo. Modelar la variabilidad en el número de consultas infantiles diarias por motivos respiratorios como consecuencia de los cambios diarios en los niveles de contaminación ambiental, observada en los servicios de urgencias y medicina familiar de un hospital de especialidades del Instituto Mexicano del Seguro Social ubicado en la zona suroeste de la Ciudad de México durante 1993. Material y métodos. Se estudió la correlación entre la presencia de infecciones respiratorias altas y bajas con la exposición a ozono y bióxido de nitrógeno. Para modelar esta asociación se utilizó la técnica de regresión Poisson aplicada sobre modelos de riesgo lineal y no lineal con periodos de latencia entre las mediciones ambientales y la consulta de uno, dos y tres días, así como el promedio de las mediciones de los tres, cinco y siete días previos a la consulta. Resultados. El modelo utilizado estima que un incremento de 50 ppb en el promedio horario de ozono de un día ocasionaría, al día siguiente, un incremento del 9.9% en las consultas de urgencias por infecciones respiratorias altas en el periodo invernal, pudiendo incrementarse hasta en un 30% si el incremento se diera en cinco días consecutivos como promedio. Conclusiones. Los resultados sugieren que la exposición de los menores de 15 a os al ozono y bióxido de nitrógeno inciden significativamente sobre el número de consultas ocasionadas por motivos respiratorios en esta zona de la Ciudad de México.
Efecto de la contaminación ambiental sobre las consultas por infecciones respiratorias en ni?os de la Ciudad de México
TéLLES-ROJO,MARTHA MARíA; ROMIEU,ISABELLE; POLO-PEA,MARCO; RUIZ-VELASCO,SILVIA; MENESES-GONZáLEZ,FERNANDO; HERNáNDEZ-AVILA,MAURICIO;
Salud Pública de México , 1997, DOI: 10.1590/S0036-36341997000600004
Abstract: objective. to model the variability of medical visits by children for respiratory reasons as a consequence of the daily changes in environmental pollution observed in the emergency and family medicine departments of a hospital of the instituto mexicano del seguro social located in the southwest of mexico city during 1993. materials and methods. the correlation between the presence of upper and lower respiratory tract infections and exposure to ozone and nitrogen dioxide was studied. to model this association, the authors used multivariate poisson regression models with linear and non-linear risk, with lag periods between the environmental measurements and the medical visits of one, two and three days, as well as the average of the measurements of three, five and seven days previous to the visit. results. the model estimates that an increment of 50 ppb in the daily average of ozone would cause an increase of 9.9% in emergency visits due to high respiratory tract infections during the winter, which could rise to 30% if the increment would last five consecutive days in average. conclusions. results suggest that exposure of children younger than 15 years of age to ozone and nitrogen dioxide significantly affect the number of medical visits for respiratory causes in this part of mexico city.
Rese a de "Propiedades del primer sistema de teledetección hiperespectral chileno"
Marco A. Pea
Revista de Geografía, Norte Grande , 2010,
Abstract:
Liometopum Apiculatum (Formicidae: Dolichoderinae) y su relacion trofobiotica con Hemiptera Sternorrhyncha en Tlaxco, Tlaxcala, México
Cecilia Velasco Corona,María del Carmen Corona Vargas,Rebeca Pea Martínez
Acta zoológica mexicana , 2007,
Abstract: Se estudió la relación trofobiótica de Liometopum apiculatum Mayr, un insecto comestible de importancia económica conocido como escamol o cuije , con hemipteros esternorrincos en el estado de Tlaxcala. Se encontraron catorce especies con las que se asoció L. apiculatum entre las que destacan siete especies de áfidos, dos del género Cinara, además de Anoecia cornicola (Walsh), Aphis lugentis Williams, Aphis solitaria (McVicar Baker), Aphis helianthi Monell in Riley & Monell, y Aphis sp. seguidas de tres especies de escamas del género Saissetia, entre ellas S. olee (Olivier) dos especies de pseudocóccidos, entre ellas Dysmicoccus brevipes (Cockerell); una especie de Ortheziidae y una Dactylopiidae: Eriococcus sp. Sólo siete especies estuvieron presentes todo el a o, el género Cinara con dos especies y Anoecia cornicola, D. brevipes, S. oleae, S. sp. y Eriococcus sp., las demás variaron estacionalmente en relación a su hospedero. El mayor número de asociaciones hormiga hemíptero fue de diez se presentó en agosto. La abundancia relativa de Cinara spp. varió más durante el a o que las de D. brevipes y S. oleae. Este es el primer registró de asociación de las especies de áfidos mencionadas con hormigas en el país y en especial la asociación Pinus rudis-Cinara sp.1- L. apiculatum y Juniperus deppeana-Cinara sp.2-Liometopum apiculatum constituyen nuevos registros de hospederos y están formadas por especies nativas americanas que se encuentran en un área ecológica relativamente frágil, que podrían constituir un modelo para la conservación por sus implicaciones biológicas y económicas.
Cuando la tostada resbala de la mano!
Adrián Corona Cruz,Guillermo Martínez Pea
Latin-American Journal of Physics Education , 2008,
Abstract: The behavior of the toast falling from a hand is used for studying the dynamics of the rotational systems. The systemhas already been studied, considering the slip of the toast of the right-angled edge of a table. However, this situation isno very likely in real life. If the toasts fall, it is more likely they will fall from a hand. It is natural to model the edge ofa hand as being round. The experimental values of the maximum angular speed that acquires the toast in falling ofround edges turned out to be bigger than those in the case of the falls of a right-angled edge. We study the effect of theroundness in the angular speed of a parallelepiped (table) that simulates a toast when falling from the round edge of asurface. The table is made fall to different salient with the objective of determining the effect that has the initialposition in the angle that the table arrives to the floor. The angular speed of rotation of the table was determined fromthe sequence of the images of its video. To know the effect of the roundness of the edge, three radios they wereidentified: the first one refers to a right-angled edge; the second to a round edge (R=1.1 cm) that simulates the edge ofthe palm of a hand; and the third (R=1.75 cm) that simulates the edge of a table. The experimental results are describedwell by the numeric solution (simulation by the software Interactive Physics, IP), a model that makes simple to predictthe different behaviors and to evaluate the effect of the physical parameters involved in the dynamics of the system.
Razonamientos científicos de estudiantes universitarios: Aros contenidos rodando en una rampa
Adrián Corona Cruz,Guillermo Martínez Pea
Latin-American Journal of Physics Education , 2010,
Abstract: The competition between objects that roll on a ramp is an activity used frequently in the basic levels to challenge students’ previous ideas. From the perspective of the study of the dynamics of rotating objects, this is to show to the students the effect of the distribution of mass on their movement in order that the students infer or discover that an object with lower rotational energy will win the race. On the other hand, it is to highlight that the acceleration of rolling objects does not depend on their radios and their masses. In this work, a critique of the approach the textbooks have on this problem is presented and the ideas, students revealed as predictions in an activity of Predict – Observe – Explain, are reported. Students only made use of their previous ideas related to friction, mass and weight. They were essentially unable to identify the distribution of mass as a decisive cause in the movement of different rolling objects (inserted rings competing with another parallel ring and a ring with an inserted cylinder).
Conducción térmica en una varilla de cobre
Adrián Corona Cruz,Guillermo Martínez Pea
Latin-American Journal of Physics Education , 2011,
Abstract: The propagation of heat is one of the basic research topics of thermodynamics, which are generally complex in that it involves mathematical modeling, nonlinear differential equations. However, in a basic level, there are cases that areanalytically and experimentally possible to solve. In this research, students explored experimentally the spatial and temporal evolution of heating a copper rod. A good correlation was found between the solution of the Fourier thermal conductivity, used to describe the evolution of temperature along a metal rod, and the experimental values measured by the students.
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