Characteristics and potentials of selected soils in the Peten Region of Guatemala

A pedological study of tropical soils in and around the Mayan Biosphere Reserve in Peten, Guatemala was undertaken in order to study the characteristics and potentials of different soils for the better management of natural resources. The objectives of this research were: i) to describe the main characteristics of selected soils in the Peten; ii) to better understand the genesis of these soils; iii) to classify the soils according to the U.S. soil taxonomy system; and iv) to determine the potentials and management of the soils. With the cooperation of several Guatemalan institutions, six sites were chosen and the soils at each site were fully characterized. After field characterization, the soil samples were transported to the laboratory for physical and chemical analysis. The analysis includes: pH, total carbon and total nitrogen contents, organic carbon, calcium carbonate equivalent, total elemental analysis, exchangeable bases, cation exchange capacity, KCI exchangeable aluminum and exchangeable acidity, archeological extract, and particle size analysis. The first three soil sites were located in the Yaxja area. A soil-landscape position relationship was established; Mollisols occupied upland and sloping positions and Vertisols occupied depressional areas in the lowlands. The rest of the sites were scattered in other areas inside, as well as outside, the Mayan Biosphere Reserve. The soil orders found in the research area were Mollisols, Vertisols and Alfisols. The Mollisols and Vertisols developed from calcareous parent materials and the Alfisol from alluvial deposits. The soils developed from the carbonated rocks are rich in clay, especially montmorillonitic clay. The pH ranged from strongly acid (Alfisol) to moderately alkaline. The average organic matter content of the topsoil of the different sites (4.84%) is comparable to those of temperate climates. The abundance of clay and organic matter resulted in high CEC values for the first five soil sites; however, the total elemental analysis showed serious deficiencies, especially in phosphorus, potassium and nitrogen. The soils were classified as Aquic Hapludolls, Typic Endoaquerts, Typic Rendolls, Eutrochreptic Rendolls, and Typic Paleudalfs. In terms of the land capability classification, the soils were classified as: site 1: llw, site 2: lllw, site 3: Vie, site four: lie, site five: IVe and site six: llf. The soils, as well as other natural resources in the Peten, are rapidly being degraded. Mismanagement, improper use and deforestation are depleting the soils. A management system based on land layout, mulches, management of cracking, fertilization, and liming was proposed to improve the productivity of the soils. This, along with sustainable agricultural practices will reduce the degradation of the natural resources

Motivación en los Inicios del Aprendizaje del Álgebra Elemental dentro del Aula de Clases

"Motivación en los inicios del aprendizaje del álgebra dentro del aula de clases" , plantea una visión distinta, específica y dinámica de la enseñanza y aprendizaje del álgebra en sus comienzos, desde la formación primaria expresiones algebraicas hasta la manipulación de las letras dentro de las operaciones aritméticas elementales. Los conceptos (mentales y concretos) juegan un papel fundamental en la enseñanza y aprendizaje de las matemáticas y de la interacción lógica que se hagan de estos, se genera su entendimiento por tal razón planteó la pedagogía conceptual como el enfoque pedagógico a manejar, apoyado en la enseñanza geométrica del álgebra, siendo esta una prueba reflexiva como lo indica el enfoque curricular crítico-práctico. Con todo lo anterior se dio inicio al desarrollo de la propuesta pedagógica conducente a mejorar el proceso de transición (aritmética y álgebra) con el objeto de disminuir las dificultades cognoscitivas y afectivas presentes en los estudiantes a través de las actividades propuestas

Sistema estratégico para la convivencia y seguridad ciudadana, estabilización y construcción de seguridad territorial.

Las problemáticas de convivencia y seguridad ciudadana que aquejan a todos los ciudadanos, son un baluarte que la Policía Nacional debe adoptar como mecanismo integral para mejorar las condiciones de seguridad y convivencia; esto conllevando a un trabajo integral y colaborativos entre especialidades y modalidades del servicio de Policía, con el fin de generar espacios de tranquilidad durante el desarrollo de las actividades diarias de todos los habitantes de Colombia, a fin de que estos convivan en paz. En esta investigación, nos muestra como a través de un Sistema estratégico para la convivencia y seguridad ciudadana, nos permite unificar el accionar y capacidad policial como oportunidad de una lucha frontal contra el crimen, pues solo a través de una articulación y un trabajo corresponsable se podrá lograr un fortalecimiento a la seguridad ciudadana.Resumen ; Introducción ; 1.Tema de investigación ; 2. Problema de investigación ; 3. Pregunta de investigación ; 4. Objetivos ; 5. Objetivos específicos ; 6. Hipótesis ; 7. Estado del arte ; 8. Marco teórico ; 9. Construcción y despliegue del sistema estratégico para la seguridad ciudadana ; 11. Armonización de la política pública con las problemáticas de atención en temas de seguridad ; 12. Componentes ; 13. Análisis de datos ; 14. Análisis de resultados - encuesta ; Conclusiones.Magíster en Administración de Empresas, CESA

Soil contamination in colombian playgrounds: effects of vehicles, construction, and traffic

The presence of potentially hazardous elements (PHEs) in playground soils is generally associated with anthropogenic sources such as vehicle traffic, industries, construction sites, and biomass burning. Studies indicate that PHEs are harmful to human health and may even be carcinogenic. Therefore, the aim of this study was to evaluate the physicochemical, morphological, and mineralogical properties of soil samples from three public playgrounds located in the cities of Bogota, Medellin, and Barranquilla. Besides, the possible impacts caused by the aerodynamics of particles in Colombian cities were verified. The morphology, composition, and structure of the nanoparticles (NPs) (< 100 nm) present in these soils were evaluated by field emission scanning electron microscopy (FE-SEM) equipped with high-precision field emission (FE) and high-resolution transmission electron microscopy (HR-TEM). Soil samples were predominantly feldspar, quartz, and, to a lesser extent, clay minerals, carbonates, and hematites. The average content of PHEs was anthropogenically enriched in relation to the upper continental crust. As and Sn showed a large spatial variation, indicating the influence of local sources, such as vehicle traffic and industries. There is an inverse relationship between the total concentrations of some elements and their leachable fractions. The accumulation of traffic-derived PHEs has a negative impact on human health and the environment, which is alarming, especially for elements such as Pb, Sb, or As. Therefore, the presence of PHEs should receive greater attention from public health professionals, and limits should be set and exposures controlled. This study includes the construction of a baseline that provides basic information on pollution, its sources, and exposure routes for humans in the vicinity of Colombia’s major cities, characterized by their increasing urbanization and industrialization

BRAF and TERT mutations in papillary thyroid cancer patients of Latino ancestry.

Papillary thyroid cancer (PTC) is the second most commonly diagnosed malignancy in U.S. Latinas and in Colombian women. Studies in non-Latinos indicate that BRAF and TERT mutations are PTC prognostic markers. This study aimed to determine the prevalence and clinical associations of BRAF and TERT mutations in PTC Latino patients from Colombia. We analyzed mutations of BRAF (V600E) and TERT promoter (C228T, C250T) in tumor DNA from 141 patients (75 with classical variant PTC, CVPTC; 66 with follicular variant PTC, FVPTC) recruited through a multi-center study. Associations between mutations and clinical variables were evaluated with Fisher exact tests. Survival was evaluated with Kaplan-Meier plots. Double-mutant tumors (BRAF+/TERT+, n = 14 patients) were more common in CVPTC (P = 0.02). Relative to patients without mutations (n = 48), double mutations were more common in patients with large tumors (P = 0.03), lymph node metastasis (P = 0.01), extra-thyroid extension (P = 0.03), and advanced stage (P = 6.0 × 10-5). In older patients, TERT mutations were more frequent (mean age 51 years vs 45 years for wild type TERT, P = 0.04) and survival was lower (HR = 1.20; P = 0.017); however, given the small sample size, the decrease in survival was not statically significant between genotypes. Comparisons with published data in US whites revealed that Colombian patients had a higher prevalence of severe pathological features and of double-mutant tumors (10 vs 6%, P = 0.001). Mutations in both oncogenes show prognostic associations in Latinos from Colombia. Our study is important to advance Latino PTC precision medicine and replicates previous prognostic associations between BRAF and TERT in this population

The HABP2 G534E polymorphism does not increase nonmedullary thyroid cancer risk in Hispanics.

Familial nonmedullary thyroid cancer (NMTC) has not been clearly linked to causal germline variants, despite the large role that genetic factors play in risk. Recently, HABP2 G534E (rs7080536A) has been implicated as a causal variant in NMTC. We have previously shown that the HABP2 G534E variant is not associated with TC risk in patients from the British Isles. Hispanics are the largest and the youngest minority in the United States and NMTC is now the second most common malignancy in women from this population. In order to determine if the HABP2 G534E variant played a role in NMTC risk among Hispanic populations, we analyzed 281 cases and 1105 population-matched controls from a multicenter study in Colombia, evaluating the association through logistic regression. We found that the HABP2 G534E variant was not significantly associated with NMTC risk (P=0.843) in this Hispanic group. We also stratified available clinical data by multiple available clinicopathological variables and further analyzed the effect of HABP2 on NMTC presentation. However, we failed to detect associations between HABP2 G534E and NMTC risk, regardless of disease presentation (P≥0.273 for all cases). Therefore, without any significant associations between the HABP2 G534E variant and NMTC risk, we conclude that the variant is not causal of NMTC in this Hispanic population

Production of Green Diesel from Castor Oil over Alumina-supported Nickel-Molybdenum Catalysts

RESUMEN: Se sintetizaron dos catalizadores tipo Ni-Mo soportados sobre -Al2O3, con diferentes contenidos másicos de los metales activos, y su actividad catalítica en el proceso de desoxigenación de aceite de higuerilla fue evaluada y comparada con el desempeño obtenido con un catalizador comercial. Previo a las reacciones de desoxigenación, los catalizadores fueron reducidos y sulfurados con H2S producido in-situ. Los catalizadores fueron caracterizados mediante DRX, adsorción-desorción de N2 a 77 K, XRF y TPR. Las pruebas catalíticas fueron llevadas a cabo en un reactor de alta presión (Parr, 500 mL), operando en modo semi-batch. El mayor rendimiento másico hacia diésel renovable (C9-C24) fue del 82.9% y se obtuvo con el catalizador sintetizado que contiene 4.5% NiO y 20% MoO3, evaluado a 350°C, 90 bares y una concentración del 10%. Además, este catalizador, bajo estas condiciones, presentó una conversión del 100% y las selectividades más altas hacia C17 (54.4%) y C18 (20.9%), así como una menor selectividad a craqueados (0.83%).ABSTRACT: Catalysts of Ni-Mo type with different content of active species (Ni,Mo) were synthesized and supported over Y-alumina and their catalytic activity in the deoxygenation process of castor oil was evaluated and compared with that obtained with a commercial catalyst. Prior to deoxygenation reactions, the catalysts were reduced and sulfurated with H2S produced in-situ. The catalysts were characterized by XRD, N2 adsorption-desorption at 77K, XRF and TPR. The catalytic tests were carried out in a high-pressure reactor (Parr, 500 mL), operating in semi-batch mode. It was found that the highest mass yield to renewable diesel (C9-C24) was 82.9%, obtained with the synthesized catalyst containing 4.5% NiO and 20% MoO3 operating at 350 °C, 90 bars and 10% catalyst concentration. Besides, this catalysts exhibited 100% conversion and the highest selectivities to C17 (54.4%) and C18 (20.9%), as well as the lowest selectivity to cracked products (0.83%)

Variaciones de los signos vitales en estudiantes de odontología durante su primer procedimiento quirúrgico

Antecedentes: el estrés académico representa un desequilibrio psíquico con posibles consecuencias académicas y médicas con una mayor prevalencia en estudios del área de la salud, como los estudiantes de odontología. Está bien documentado que el estado psíquico se relaciona con las variaciones en los sistemas biológicos y se refleja a través de medidas como los signos vitales. Objetivo: determinar las variaciones de los signos vitales (frecuencia cardíaca, frecuencia respiratoria y temperatura) en los estudiantes de odontología durante su primera exodoncia. Materiales y Métodos: se utilizó un diseño longitudinal prospectivo para tomar tres medidas de los signos vitales y observar sus variaciones antes, durante y después del primer procedimiento dental realizado por los estudiantes durante su carrera. Resultados: Se evaluó un total de 42 estudiantes, con una edad media de 20,43 años y una proporción de mujeres de 71,4%. Antes del procedimiento se observó un ligero aumento en los valores de frecuencia cardíaca, frecuencia respiratoria y presión sanguínea (96 lpm, 22 rpm y 127/83 mmHg respectivamente para el promedio), los cambios de temperatura fueron inferiores de 36,52 ° C a 36,87 ° C. Los signos vitales evaluados muestran cambios con significación estadística respecto al estado previo durante las tres tomas, siendo este cambio el más evidente en la frecuencia respiratoria; Las variaciones pueden persistir después del final del procedimiento. Conclusión: el estrés y la angustia académica están presentes en los estudiantes, especialmente durante las etapas de transición, como el inicio de las actividades clínicas y quirúrgicas, que se reflejan en un componente biológico medible. Los profesores deben ser conscientes de estas manifestaciones y orientar a los estudiantes hacia mecanismos de adaptación más saludables para hacer frente a la transición