oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 244 )

2018 ( 337 )

2017 ( 344 )

2016 ( 545 )

Custom range...

Search Results: 1 - 10 of 201857 matches for " Beltrán-Aguilar Eugenio "
All listed articles are free for downloading (OA Articles)
Page 1 /201857
Display every page Item
Methodological and biological factors explaining the reduction in dental caries in Jamaican school children between 1984 and 1995
Warpeha,Rosalie; Beltrán-Aguilar,Eugenio; Báez,Ramón;
Revista Panamericana de Salud Pública , 2001, DOI: 10.1590/S1020-49892001000700006
Abstract: objective. to assess the methods used and results found in two surveys, one conducted in 1984 and the other in 1995, that indicated a large reduction in the prevalence and severity of dental caries among children in jamaica, with special attention focused on methodological differences between the two surveys and the biological factors that may explain the large reduction in caries. methods. in 1984 a modified "pathfinder" methodology was used to measure the prevalence and severity of dental caries in 6-, 12-, and 15-year-old children in jamaica. a similar survey was conducted in 1995. a comparison of the two surveys showed an 84% reduction in the severity of dental caries at age 12. both surveys used the same diagnostic criteria and clinical procedures, but the 1984 survey included a higher proportion of rural residents than did the 1995 one. results. the data show an epidemiological transition between 1984, when dental caries was highly prevalent and severe, and 1995, when the disease was less prevalent and was concentrated in a smaller proportion of the population. conclusions. most of the reduction in dental caries between 1984 and 1995 is attributable to the introduction, in 1987, of salt fluoridation. while the 1995 survey included fewer rural areas than the 1984 survey did, that does not invalidate the observed reduction in dental caries. the use of fluoride toothpaste and dietary fluoride supplements as well as access to dental health promotion and preventive and curative services do not seem to be major contributors to the reductions observed.
Methodological and biological factors explaining the reduction in dental caries in Jamaican school children between 1984 and 1995
Warpeha Rosalie,Beltrán-Aguilar Eugenio,Báez Ramón
Revista Panamericana de Salud Pública , 2001,
Abstract: Objective. To assess the methods used and results found in two surveys, one conducted in 1984 and the other in 1995, that indicated a large reduction in the prevalence and severity of dental caries among children in Jamaica, with special attention focused on methodological differences between the two surveys and the biological factors that may explain the large reduction in caries. Methods. In 1984 a modified "pathfinder" methodology was used to measure the prevalence and severity of dental caries in 6-, 12-, and 15-year-old children in Jamaica. A similar survey was conducted in 1995. A comparison of the two surveys showed an 84% reduction in the severity of dental caries at age 12. Both surveys used the same diagnostic criteria and clinical procedures, but the 1984 survey included a higher proportion of rural residents than did the 1995 one. Results. The data show an epidemiological transition between 1984, when dental caries was highly prevalent and severe, and 1995, when the disease was less prevalent and was concentrated in a smaller proportion of the population. Conclusions. Most of the reduction in dental caries between 1984 and 1995 is attributable to the introduction, in 1987, of salt fluoridation. While the 1995 survey included fewer rural areas than the 1984 survey did, that does not invalidate the observed reduction in dental caries. The use of fluoride toothpaste and dietary fluoride supplements as well as access to dental health promotion and preventive and curative services do not seem to be major contributors to the reductions observed.
TAXONOMíA Y DISTRIBUCIóN DE LOS ANOFELINOS EN EL ESTADO DE VERACRUZ, MéXICO (DIPTERA: CULICIDAE, ANOPHELINAE)
Adriana Beltrán-Aguilar,Sergio Ibá?ez-Bernal,Fredy Mendoza-Palmero,César A. Sandoval-Ruiz
Acta zoológica mexicana , 2011,
Abstract: La malaria o paludismo es una enfermedad humana causada por protozoarios del género Plasmodium y es transmitida por hembras de mosquito de ciertas especies de Anopheles. Se estima que en México el 33.1% de la población vive en áreas donde puede ocurrir la transmisión de la malaria. Veracruz es un estado donde la enfermedad es endémica debido a diversos factores que lo hacen una zona de riesgo para la transmisión, entre ellos las condiciones climáticas y la migración humana. Por lo anterior, en este trabajo se presentan las bases para la reactivación de la vigilancia entomológica del paludismo en el estado de Veracruz, para lo cual se provee la diagnosis ilustrada de la larva, la pupa y los adultos de ambos sexos de las especies de anofelinos del estado, así como las claves taxonómicas que permiten su reconocimiento, con base en el examen de ejemplares recolectados o depositados en colecciones entomológicas de referencia. También se obtuvieron mapas de distribución conocida y potencial de las especies por medio de GARP. Se mencionan además algunos datos bionómicos y la importancia médica de cada especie. Se conocen en Veracruz 18 especies de anofelinos, agrupadas en dos géneros, Chagasia con una especie y Anopheles con 17 pertenecientes a los subgéneros An. (Anopheles), An. (Kerteszia) y An. (Nyssorhynchus). Se reconocen cuatro grupos de especies de acuerdo a su capacidad de transmisión de plasmodios y por su amplitud de distribución: el grupo de alto riesgo constituido por 2 especies; el grupo de riesgo moderado o regional, con 8 especies; el de escaso riesgo, con 3 especies y el de riesgo nulo con 5 especies. Prácticamente todo el estado posee vectores potenciales por lo que debe reestablecerse la vigilancia permanente de sus poblaciones. Este trabajo aporta elementos de juicio para que el estado pueda ser, en un futuro cercano, certificado como área libre de paludismo.
Security Regulations in Mexican Renewable Energies: Case of Geothermal Projects  [PDF]
Alfonso Aragón-Aguilar, Georgina Izquierdo-Montalvo, Víctor Arellano-Gómez
Smart Grid and Renewable Energy (SGRE) , 2013, DOI: 10.4236/sgre.2013.46A003
Abstract:

A review of natural resources existing in México is done. The description of the renewable energies for electricity generation operating at date along the country, includes hydro, wind, solar, biomass and geothermal, among others. The installed capacity (to 2012) in México for electric generation from renewable energies is equivalent to 22% of total generation capacity. México has geothermal resources, which can be classified as high and low enthalpy, and of hot dry rock. To date, the exploitation has focused mainly on high enthalpy geothermal fields. Geothermal power plants do not burn fuel, preventing gas emissions helping to reduce global warming and greenhouse effect. Security risks in México geothermal fields, as a part of renewable energies linked to Smart Grids, are described emphasizing their geographical locations to facilitate the exposure to dangerous events. The results about research on Mexican Official Norms protecting environment related with geothermal operation projects are shown. The Mexican geothermal projects have developed under rules that provide security to workers and people, avoiding impacts on the environment. However, it was found that it necessarily emphasized previsions to damages and remedial actions for grids due to risks by natural contingencies (cyclones, winds, earthquakes) and by artificial causes such as vandalism (grids breaking, fire, explosions, etc.). Unfortunately, there are no preventive norms against natural risks. After all the analyses carried out, security must be considered by nature a dynamic and ever-changing process.

Kikuchi-Fujimoto Disease Associated to the Epstein-Barr Virus. A Type of Rare Necrotizing Lymphadenitis and Its Differential Diagnosis  [PDF]
Mónica Belinda Romero Guadarrama, Oscar Daniel Guzmán-Aguilar, Adriana Carolina López-Ugalde, José Samuel Almeida Navarro, Humberto Cruz-Ortíz
Open Journal of Pathology (OJPathology) , 2013, DOI: 10.4236/ojpathology.2013.34034
Abstract: Introduction: Kikuchi-Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, is a specific and self-limited disease; its etiology is unknown. Some causal microorganisms have been proposed. The objective of the present article is to emphasize the clinicopathological characteristics of this disease that has been associated to the Epstein-Barr virus and to compare the histological changes with other types of necrotizing lymphadenopathies. Material and Methods: We studied 32 patients of the Surgical Pathology Service with necrotizing lymphadenitis, diagnosed in the years from 2004 to 2012 to found more cases of this rare disease in our Institution. Patients were 18 women and 14 men with an average age of 37 years. Results: The lymph nodes were cervical and axillary ones, some were associated to autoimmune diseases and no cause was identified in others. One of the cases, was diagnosed as KFD, presented morphological changes characteristic of this disease, such as subcapsular lymphoid follicles, zones with cell debris, epithelioid macrophages, clear-cytoplasm histiocytes, and immunoblast-reactive lymphocytes. Immunohistochemical markers were determined, such as CD20, CD2, CD4, CD8, CD68, lysozyme, CD56, granzyme B and EBER, which demonstrated the presence of B, T lymphocytes, histiocytes and cells positive to EBER. Histological changes in KFD occurred in three stages: proliferative stage, necrotizing, and xanthomatous. It is important to identify the histological stages of the disease because a differential diagnosis must be performed in regard to lymphadenopathies with necrosis and diverse types of lymphomas. Conclusion: We present a case of necrotizing lymphadenitis (KFD) associated to the Epstein-Barr virus and in some cases it is not possible to render a specific diagnosis based on morphologic findings, alone, and a diagnosis of necrotizing lymphadenitis may be used.

 

Shark breeding grounds and seasons in the Gulf of California: Fishery management and conservation strategy
Salomón-Aguilar, CA;Villavicencio-Garayzar, CJ;Reyes-Bonilla, H;
Ciencias marinas , 2009,
Abstract: sharks show high biological fragility and, given the intense fishing regimes to which they are exposed in the gulf of california, it is necessary to establish a conservation and management strategy providing for the protection of their nursery areas. we reviewed the literature concerning shark reproductive biology to determine priority management areas in the gulf of california by complementarity analysis and different selection criteria. four levels of management and conservation priority were determined for six quadrants: level 1 corresponded to the area off mazatlán (sinaloa) and the area of el sargento, la ventana, and punta arenas (baja california sur); level 2 to the areas of teacapán (sinaloa) and seri (sonora); level 3 to the areas of san francisquito-el barril (baja california) and kino bay (sonora); and level 4 to the area of la manga (sonora). analysis of space-time variables in a geographic information system indicated that 71% of the commercially important shark species concentrate in coastal zones, mainly in bays, coastal lagoons, estuaries, and wetlands (central and southern gulf of california) during spring and summer (may-august), except for prionace glauca, isurus oxyrinchus, alopias pelagicus, and squatina californica that reproduce in winter and spring. the protection of recruitment areas (critical habitats) during peak breeding periods should be an essential part of any resource management plan.
HIGH- EFFICIENCY CLASS E POWER AMPLIFIER USING SI-GE HBT TECHNOLOGY
J.A. Tirado-Méndez,H. Jardón-Aguilar
Journal of applied research and technology , 2004,
Abstract: One of the most important goals of RF circuit designers is improving efficiency and autonomy in handsets forpersonal communications. Currently, low-level voltage supplies are used to avoid big weight and volume. Besides,autonomy and efficiency are closely linked to the energy consumed by the circuits. Power Amplifier (PA) is one ofthe circuits, which spends more energy from the battery. Improving the PA efficiency, handset performance is alsoimproved. Previous publications have mentioned the difference of power amplifiers where the circuit output worksas I) a current source or II) as a switch. The class E power amplifiers are devices whose output works as a switchachieving great performance and high power efficiency, reaching, in an ideal case, 100 % of efficiency. In thispaper, a low-level voltage class E power amplifier is analyzed, designed, simulated, built and characterized, using asilicio-Germains HBT transistor as an active element. The circuit was optimized using a harmonic balanced simulator(Microwave Office [1]). 70% power efficiency was measured after an optimizing procedure, although betterperformance can be expected with an improved switching transistor and more precisely lumped elements. Theprototype was designed to operate at 900 MHz and fed with 2.4 V, but it is well known that low-level polarizationvoltages affect efficiency, linearity, power gain, bandwidth, noise figure, as well as cost in RF circuits. However theclass E PA reported in this paper reaches high efficiency, high power gain as well as a good bandwidth, with lowlevelpolarization voltage.
Smoothed Particle Hydrodynamics simulations of white dwarf collisions and close encounters
P. Lorén-Aguilar,J. Isern,E. García-Berro
Physics , 2010, DOI: 10.1111/j.1365-2966.2010.16878.x
Abstract: The collision of two white dwarfs is a quite frequent event in dense stellar systems, like globular clusters and galactic nuclei. In this paper we present the results of a set of simulations of the close encounters and collisions of two white dwarfs. We use an up- to-date smoothed particle hydrodynamics code that incorporates very detailed input physics and an improved treatment of the artificial viscosity. Our simulations have been done using a large number of particles (~ 4 \times 10^5) and covering a wide range of velocities and initial distances of the colliding white dwarfs. We discuss in detail when the initial eccentric binary white dwarf survives the closest approach, when a lateral collision in which several mass transfer episodes occur is the outcome of the newly formed binary system, and which range of input parameters leads to a direct collision, in which only one mass transfer episode occurs. We also discuss the characteristics of the final configuration and we assess the possible observational signatures of the merger, such as the associated gravitational waveforms and the fallback luminosities. We find that the overall evolution of the system and the main characteristics of the final object agree with those found in previous studies. We also find that the fallback luminosities are close to 10^48 erg/s. Finally, we find as well that in the case of lateral and direct collisions the gravitational waveforms are characterized by large-amplitude peaks which are followed by a ring-down phase, while in the case in which the binary white dwarf survives the closest approach, the gravitational pattern shows a distinctive behavior, typical of eccentric systems.
High-resolution Smoothed Particle Hydrodynamics simulations of the merger of binary white dwarfs
P. Lorén-Aguilar,J. Isern,E. García-Berro
Physics , 2009, DOI: 10.1063/1.3141311
Abstract: We present the results of a set of high-resolution simulations of the merging process of two white dwarfs. In order to do so, we use an up-to-date Smoothed Particle Hydrodynamics code which incorporates very detailed input physics and an improved treatment of the artificial viscosity. Our simulations have been done using a large number of particles (4x10^5) and cover the full range of masses and chemical compositions of the coalescing white dwarfs. We also compare the time evolution of the system during the first phases of the coalescence with that obtained using a simplified treatment of mass transfer, we discuss in detail the characteristics of the final configuration, we assess the possible observational signatures of the merger, like the associated gravitational waveforms and the fallback X-ray flares, and we study the long-term evolution of the coalescence.
Type Ia supernovae and the DD scenario
J. Isern,E. García-Berro,P. Lorén-Aguilar
Physics , 2011,
Abstract: Type Ia supernovae are thought to be the outcome of the thermonuclear explosion of a white dwarf in a close binary system. Two possible scenarios, not necessarily incompatible, have been advanced. One assumes a white dwarf that accretes matter from a nondegenerate companion (the single degenerate scenario), the other assumes two white dwarfs that merge as a consequence of the emission of gravitational waves (the double degenerate scenario). The delay time distribution of star formation bursts strongly suggests that the DD scenario should be responsible of the late time explosions, but this contradicts the common wisdom that the outcome of the merging of two white dwarfs is an accretion induced collapse to a neutron star. In this contribution we review some of the most controversial issues of this problem.
Page 1 /201857
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.