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Search Results: 1 - 10 of 5053 matches for " Arreola-Ortiz "
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Análisis de sequías y productividad con cronologías de Pseudotsuga menziesii Rob. & Fern., y su asociación con El Ni?o en el nordeste de México
Arreola-Ortiz, María Rafaela;Návar-Cháidez, José de Jesús;
Investigaciones geográficas , 2010,
Abstract: this research was conducted to construct chronologies, to understand climatic shifts, and to determine productivity changes of psesudotsuga menziensii mirb. franco of the sierra madre oriental mountain range of nuevo león, méxico. radial growth patterns, drought episodes and productivity data were studied from the tree rings growth patterns during a 120 years study period. we also studied the association between recorded climate parameters and that hit chronologies using data of four climatic stations. chronologies were also associated to global scale climate events, the multivariate enso index (mei) and climate parameters associated to chronologies were reconstructed. it was noted that chronologies show four main drought episodes (1885-1903, 1907-1937, 1950-1963, and 1998-2003) that hit the highlands of northeastern mexico. productivity has a mean radial growth values of 0.82 mm y-1 and 1.18 mm y-1 during drought and wet episodes, respectively. there is a good association between chronologies and winter rainfall. reconstructed winter rainfall shows an increasing pattern in time and the mei is negatively associated to the chronologies indicating that the presence of wet and cold winters and early spring promote radial growth of trees in northern mexico.
Análisis de sequías y productividad con cronologías de Pseudotsuga menziesii Rob. & Fern., y su asociación con El Ni o en el nordeste de México
María Rafaela Arreola-Ortiz,José de Jesús Návar-Cháidez
Investigaciones geográficas , 2010,
Abstract: Con tres cronologías de Pseudotsuga menziesii Mirb. Franco obtenidas en la Sierra Madre Oriental (SMO), en el estado de Nuevo León, México, se determinaron periodos de sequías y productividad analizando el patrón de crecimiento radial durante un lapso de 120 a os. Se estudió la asociación entre el índice de crecimiento radial de las cronologías y los registros instrumentales de factores climáticos (precipitación y temperatura), obtenidos de cuatro estaciones meteorológicas vecinas a los sitios de muestreo. Se asociaron las cronologías con el índice multivariado del ENSO (MEI). Los resultados indican que en las cronologías resaltan cuatro periodos de sequías que se presentaron entre los a os: 1885-1903, 1907-1937, 1950-1963 y 1998-2003. La productividad disminuye notablemente de 1.18 mm a o-1 de crecimiento radial en épocas húmedas a 0.82 mm a o-1 durante la presencia de sequías. Existe buena asociación entre el índice de Crecimiento Radial Estandarizado (ICRE) de las cronologías con la precipitación invernal observada. La reconstrucción de la precipitación invernal basada en las cronologías, muestra un ascenso paulatino a través del tiempo, desde 1880 hasta 2003. La correlación del ICRE de las tres cronologías y el MEI presenta buena asociación en la mayoría de los meses del a o, principalmente, durante los meses que cubren las estaciones de oto o, invierno y primavera, indicando que el crecimiento del ancho de los anillos se ve favorecido con la presencia de bajas temperaturas y precipitaciones por arriba del promedio durante el invierno o la etapas primarias de la primavera.
Dendrocronología de Pseudotsuga menziesii (Mirb.) Franco de la Sierra Madre Oriental en Nuevo León, México
Arreola-Ortiz, María Rafaela;González-Elizondo, Martha;Návar-Cháidez, José de Jesús;
Madera y bosques , 2010,
Abstract: tree-ring chronologies for pseudotsuga menziesii were constructed for three sites of the sierra madre oriental mountain range of the state of nuevo leon, mexico: el potosí, la encantada and la marta. the correlation coefficients between chronologies, the normality tests on the ring width, and an index of ring width indicate both, the climate regionalization and the decadence on diameter growth of pseudotsuga menziesii (mirb.) franco populations. potential subtle climatic changes may be contributing to the decline of radial growth of the three plant communities studied.
Clinical and microbiological features of vulvovaginitis in Mexican girls  [PDF]
Mario I. Ortiz, Edna J. Arreola-Bautista, Beatriz A. Sánchez-Reyes, Beatriz A. Sánchez-Reyes, Marco A. Escamilla-Acosta
Open Journal of Obstetrics and Gynecology (OJOG) , 2013, DOI: 10.4236/ojog.2013.32046

Study Objective: To determine the prevalence of vulvovaginitis, predisposing factors, microbial etiology and therapy in patients treated at the Hospital del Nino DIF, Pachuca, Hidalgo, Mexico. Design. This was an observational and descriptive study from 2006 to 2009. Setting: Hospital del Nino DIF, Pachuca, Hidalgo, Mexico. Participants. Patients from 0 to 16 years, with vulvovaginitis and/or vaginal discharge were included. Interventions: None. Main Outcome Measures: Demographic data, etiology, clinical features, risk factors and therapy were analyzed. Results: Four hundred twenty seven patients with diagnosis of vulvovaginitis were included. The average prevalence to 4 years in the study period was 0.19%. The age group most affected was schoolchildren (225 cases: 52.69%). The main signs and symptoms presented were leucorrhea (99.3%), vaginal hyperemia (32.6%), vulvar itching (32.1%) and erythema (28.8%). Identified risk factors were poor hygiene (15.7%), urinary tract infection (14.7%), intestinal parasites (5.6%) and obesity or overweight (3.3%). The main microorganisms found in vaginal cultures were enterobacteriaceae (Escherichia coli, Klebsiella and Enterococcus faecalis), Staphylococcus spp, and Gardnerella vaginalis. Several inconsistent were found in the drug prescription of the patients. Conclusion: Vulvovaginitis prevalence in Mexican girls is low and this was caused mainly by opportunist microorganisms. The initial treatment of vulvovaginitis must include hygienic measure and an antimicrobial according to the clinical features and microorganism found.

Characterization of the global profile of genes expressed in cervical epithelium by Serial Analysis of Gene Expression (SAGE)
Carlos Pérez-Plasencia, Gregory Riggins, Guelaguetza Vázquez-Ortiz, José Moreno, Hugo Arreola, Alfredo Hidalgo, Patricia Pi?a-Sanchez, Mauricio Salcedo
BMC Genomics , 2005, DOI: 10.1186/1471-2164-6-130
Abstract: We report here a transcriptome analysis of cervical tissue by SAGE, derived from 30,418 sequenced tags that provide a wealth of information about the gene products involved in normal cervical epithelium physiology, as well as genes not previously found in uterine cervix tissue involved in the process of epidermal differentiation.This first comprehensive and profound analysis of uterine cervix transcriptome, should be useful for the identification of genes involved in normal cervix uterine function, and candidate genes associated with cervical carcinoma.One of the most frequent malignancies in women worldwide is the Uterine Cervical Carcinoma (CC), both in incidence and mortality and the first cause of death among the Mexican female population [1]. High-risk human papillomavirus (HPV) persistent infection is considered the most important risk factor associated with the development of this tumor [2,3]. Although HPV is a mandatory cause for CC, it is not sufficient to trigger all the changes required for its development [4].A number of recent studies about gene expression profiles in in vitro HPV-infected cultured keratinocytes and from (CC) clinical samples have provided an initial notion of the changes in gene expression induced by HPV and in early CC [5-10]. Moreover, some studies have compared normal versus tumor-induced gene expression in cervical samples with the aim to identify potential tumor markers of clinical value [11-13].At present, there are reports of genes expressed by keratinocytes derived from a normal human epidermis and from mouse uterus carried out by Serial Analysis of Gene Expression (SAGE) [14-17]. However, no such study exists for human cervix. Therefore, the aim of our study was to describe the first compendium of expressed genes in normal cervical epithelium, which is composed mainly by keratinocytes strongly influenced by hormones. To achieve this we used SAGE, which is capable of producing an accurate molecular picture of cervical tissue ba
Fitoextracción de plomo y cadmio en suelos contaminados usando quelite (Amaranthus hybridus L.) y micorrizas
Ortiz-Cano, H. G.;Trejo-Calzada, R.;Valdez-Cepeda, R. D.;Arreola-ávila, J. G.;Flores-Hernández, A.;López-Ariza, B.;
Revista Chapingo. Serie horticultura , 2009,
Abstract: mining and metallurgy activities practiced in the comarca lagunera in mexico have contaminated soil, air and water. the use of plants is one strategy for the remediation of soils contaminated with heavy metals. however, few studies on remediation with plants of arid and semiardid zones in association with mycorrhizae have been performed. the aim of this study was to evaluate the ability of pigweed (amaranthus hybridus l.) to extract pb and cd by adding a mixture of arbuscular mycorrhizae (entrophospora columbiana, glomus intraradices, g. etunicatum, g. clarum) to the substrate contaminated with pb or cd. two experiments, one for each metal, under the basis of an experimental design with randomized blocks with four replications were carried out. the first experiment considered three doses of mycorrhizae (0, 2.5 and 5.0 g·kg-1) added to the soil contaminated with 300 mg·kg-1 pb. in the second experiment, we used the same quantities of mycorrhizae added to soil contaminated with 15 mg·kg-1 cd. the concentration of pb and cd in root, leaf and stem at 65, 95 and 125 days of age of the plant were determined with an atomic absorption spectrophotometer. the results indicate that the addition of mycorrhizae significantly increased the concentration of pb and cd in root, stem and leaf. the concentrations of pb and cd were increased significantly as the age of the plant increases.
Transición y estabilidad de fase de soluciones poliméricas en CO2 supercrítico por turbidimetría
Ortiz-Estrada, C. H.;Santoyo-Arreola, J. G.;Luna-Bárcenas, G;Sanchez, I. C.;Vásquez-Medrano, R. C.;
Revista mexicana de ingeniería química , 2007,
Abstract: the phase behavior of polymer solutions in supercritical co2 is a fundamental problem in particle formation process during the nucleation in solution, where the co2 is either used like as solvent or antisolvent. in this work, it was determined by turbidimetry, the phase transition and stability by cloud point measurements. particle size was monitored during the pressure induced phase separation from a homogeneous solution in cases where the co2 is solvent (binary system) or antisolvent (ternary system). the studied systems were poly(fluorooctyl methyacrylate) (pfoma)-co2 and polystyrene (ps)-tetrahydrofuran (thf)-co2, for different polymer concentrations, temperatures and pressures in the supercritical region of co2. the results indicate that the system pfoma-co2 exhibits an lcst and for ps-thf-co2 a combination of ucst-lcst phase behaviours are observed that is highly dependent on the thf-to-co2 concentration ratio. by monitoring particle size in solution the transition stages and phase stability of stable-metastable-unstable states, which are associated with the spinodal region, are determined. the nucleation phenomenon appears once the solution crosses the spinodal curve toward the unstable area. in this region, the growth of the particles is exponential favouring coagulation that ultimately induces supersaturation.
?Por qué el distanciamiento ideológico disminuye la provisión de bienes públicos?; una explicación basada en el empleo clientelar
Gatica Arreola,Leonardo A;
Estudios de economía , 2012, DOI: 10.4067/S0718-52862012000100002
Abstract: this paper presents a model of political competition to explore the effect that the ideological distance between two political parties has over the provision of public goods. the main result argues that the ideological distance between parties and citizens has a negative relationship with the provision of public goods. in contrast with other models, the result is explained, neither by cooperation problems nor conflict between polarized groups, but because of the political profitability of clientelistic employment.
Rese a de "Selección de candidatos, política partidista y rendimiento democrático" de Flavia FREIDENBERG y Manuel ALCáNTARA SáEZ (coords.)
América Latina Hoy , 2009,
Rese a de "México el nuevo escenario político ante el bicentenario" de Manuel ALCáNTARA SáEZ y Ernesto HERNáNDEZ NORZAGARAY (comps.)
América Latina Hoy , 2010,
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