Search

El uso inadecuado de fertilizantes en zonas altas cafetaleras del estado Lara, ha repercutido en alteraciones asociadas al equilibrio químico, físico y biológico de los suelos. Este trabajo evaluó el efecto de la aplicación de cuatro abonos orgánicos sobre el estado nutricional y el rendimiento del cultivo café. Se aplicaron cuatro abonos orgánicos producidos en la localidad: Fertipollo, Biofertilizante La Pastora, Humus CB y Capriabono, en un ensayo de campo durante dos años consecutivos. El diseño de experimento fue bloques al azar con tres repeticiones y cinco tratamientos: Testigo, suelo + Fertipollo (SFP), suelo + Biofer (SBF), suelo + Humus CB (SHCB) y suelo + capriabono (CAPR). Se analizó el contenido de N, P, K, Ca y Mg en tejido foliar y se midió el rendimiento del cultivo en g/planta. Se determinaron las relaciones de equilibrio entre (Ca+Mg)/K, Mg/K en el suelo. Los datos se procesaron con el Programa Statistix para Windows, versión 8 (Statistix, 2003). Los resultados indicaron que las relaciones nutricionales (Ca+Mg)/K y Mg/K no reflejaron una influencia clara en los equilibrios catiónicos del suelo. El tratamiento SFP elevó los nutrientes N y K. El abono orgánico SHCB aumentó los niveles de Ca, y el tratamiento CAPR los contenidos de Mg, en el segundo año de ensayo. El rendimiento mejoró significativamente con la aplicación de los abonos Fertipollo y Humus de lombriz en más de un 50 %.

"In this work we present the design and simulation of an ac oustic sensors array for detec ting specific frequencies in a range, and allowing their identification from a complex audio signal in order to develop an application for cochlear implants. The sensitivity is obtained when a membrane resonate s when stimulated by an audio signal which behaves as a mechanical wave. The structure of each sensor is designed with the concept of MEMS capacitive microphones, formed by a flexible membrane between two rigid backplates. The variat ion of the distance between the membrane and backplates generates a capacitance change that can pass to an electronic readout circuit. The structure has been designed as a mass- spring system where a set of springs, with the same elastic properties, holds the flexible membrane."

Antecedentes: En Chile el parto prematuro es la principal causa de morbilidad y mortalidad perinatal. Objetivo: Evaluar la utilidad clínica de la longitud cervical y la detección de fibronectina, en la predicción de parto prematuro. Método: Estudio observacional prospectivo, de corte transversal en 86 pacientes que consultaron por síntomas de parto prematuro (SPP), con membranas indemnes y edad gestacional entre las 22 y 34 semanas. El grupo estudio formado por gestantes con parto prematuro dentro de los 7 días. Al ingreso se tomó muestra cervical para fibronectina y se midió longitud cervical mediante ultrasonografía transvaginal. Resultados: De las 86 gestantes estudiadas, en 13 (15%) se produjo el parto dentro de los 7 días. La curva ROC mostró un área bajo la curva para longitud cervical de 0,475 y sensibilidad 31% (4/13), especificidad 96% (70/73), valor predictivo positivo 57% (4/7) y valor predictivo negativo 89% (70/79), riesgo relativo positivo 5,0 y riesgo relativo negativo 0,47 (p=0,014). El área bajo la curva para fibronectina fue 0,92 con una sensibilidad 77% (10/13), especificidad 90% (66/73), valor predictivo positivo (10/17) 59% y valor predictivo negativo 96% (66/69), riesgo relativo positivo 13,48 y riesgo relativo negativo 0,43 (p

Se utilizó un Sistema de Información Geográfica (SIG), aplicado a la vertiente sur del Parque Nacional Henry Pittier, en especial sus herramientas de análisis multi-criterio, para lo cual se digitalizaron algunas variables como topografía, uso de la tierra, hidrografía, vialidad y vegetación. Cada una de estas variables se procesó para generar los criterios de las dos capas, objetivos principales escogidas en el modelo de evaluación: riesgo de ignición (RI) y riesgo de propagación (RP). La capa objetivo RI está constituida por los criterios pisos altitudinales, uso de la tierra colindante con el parque, accesibilidad y vegetación sensible a la ignición. La capa objetivo RP fue evaluada para los criterios pendiente, vegetación sensible a la propagación, influencia del viento, pisos altitudinales, hidrografía y cortafuegos. Estos criterios se ponderaron utilizando el Método de las Jerarquías Analíticas y posteriormente se introdujeron en la regla de decisión multi-criterio estructurada e incorporada al SIG, generando la cartografía de riesgo para cada capa objetivo. Finalmente se integraron las dos capas objetivos para generar la cartografía definitiva de riesgo de incendios de vegetación. Se determinó que existen aproximadamente unas 139 ha con muy alto riesgo, 6.186 ha con alto riesgo, 3.695 ha de moderado riesgo y 728 ha con bajo riesgo a los incendios de vegetación, en promedio durante los meses afectados. Igualmente se ubicaron las zonas donde es necesario aplicar medidas de prevención y control para actuar sobre este grave problema ambiental que afecta a la población de la ciudad de Maracay y sus alrededores A GIS was used, especially their multi-criteria analysis tools, thus variables such as topography, land use, hydrography, roads and vegetation were digitized. Each one of these variables were processed to generate the criteria of the two main target layers chosen in the evaluation model: ignition risk and propagation risk. The ignition risk target layer is constituted by floors heights, park adjacent land use, accessibility and ignition sensitive vegetation criteria. The propagation risk target layer was evaluated by the slope, propagation sensitive vegetation, wind influences, floors heights, hydrography and firewalls criteria. These criteria were pondered using the Analytical Hierarchy Process and were introduced in the multi-criteria decision rule structured and incorporated into the GIS, generating the risk cartography for each target layer. Finally, the two target layers were integrated to generate the definitive vegetation fires risk cartography. It was found that exist proximately 139 ha with very high risk, 6.186 ha with high risk, 3.695 ha with moderate risk and 728 ha with low risk of fire. At the same time, there were detected areas where it is necessary to apply some practices to prevent and to control this serious environmental problem that affects Maracay city and its surroundings population.

The aim of this study was to survey the information available regarding the N400 component of event related potentials (ERP) as an electrophysiological measure of semantic processing.The N400 component of ERP is characterised, the advantages and disadvantages of studies that use this type of electrophysiological measures are presented, and the main findings of the experiments conducted in recent years to establish how N400 is related to linguistic processes are analysed. We also present some of the ways its study can be applied to understanding the brain processes underlying dementias, and especially Alzheimer s disease. The value of this component of ERP in the scientific study of mental processes is clearly illustrated.Electrophysiological measures of ERP are a very promising tool for the study of the cognitive processes that sustain the understanding and organisation of language and memory. ERP are changes in voltage that are registered on the scalp and which are synchronised with an observable (sensory, motor or cognitive) event. They are a non invasive method of monitoring brain processes in real time and as such can be used to obtain electrophysiological evidence of brain functioning and of psychological processes. The N400 component of ERP has been linked mainly to language processing and has been recorded in association with examples of semantic incongruence found in sentences, words or visually presented figures.

Background: The diagnosis of patients with short segments of intestinal metaplasia in the distal esophagus, has increased in recent years. Aim: To assess the clinical, pathological and functional features of patients with esophageal intestinal metaplasia. Patients and methods: A prospective study was performed in 95 control subjects, 115 patients with cardial intestinal metaplasia and 89 patients with short Barret esophagus with intestinal metaplasia. All had clinical and endoscopic assessments, esophageal manometry and determination of 24 h esophageal exposure to acid and duodenal content. Results: Control patients were younger and, in this group, the pathological findings in the mucosa distal to the squamous-columnar change, showed a preponderance of fundic over cardial mucosa. In patients with intestinal metaplasia and short Barret esophagus, there was only cardial mucosa, that is the place where intestinal metaplasia implants. Low grade dysplasia was only seen in the presence of intestinal metaplasia. Gastroesophageal sphincter pressure decreased and gastric and duodenal reflux increased along with increases in the extension of intestinal metaplasia. Conclusions: These findings confirm the need to obtain multiple biopsies from the squamous-columnar mucosal junction in all patients with gastroesophageal reflux symptoms, for the detection of early pathological changes of Barret esophagus and eventual dysplasia.

Background: The diagnosis of patients with short segments of intestinal metaplasia in the distal esophagus, has increased in recent years. Aim: To assess the clinical, pathological and functional features of patients with esophageal intestinal metaplasia. Patients and methods: A prospective study was performed in 95 control subjects, 115 patients with cardial intestinal metaplasia and 89 patients with short Barret esophagus with intestinal metaplasia. All had clinical and endoscopic assessments, esophageal manometry and determination of 24 h esophageal exposure to acid and duodenal content. Results: Control patients were younger and, in this group, the pathological findings in the mucosa distal to the squamous-columnar change, showed a preponderance of fundic over cardial mucosa. In patients with intestinal metaplasia and short Barret esophagus, there was only cardial mucosa, that is the place where intestinal metaplasia implants. Low grade dysplasia was only seen in the presence of intestinal metaplasia. Gastroesophageal sphincter pressure decreased and gastric and duodenal reflux increased along with increases in the extension of intestinal metaplasia. Conclusions: These findings confirm the need to obtain multiple biopsies from the squamous-columnar mucosal junction in all patients with gastroesophageal reflux symptoms, for the detection of early pathological changes of Barret esophagus and eventual dysplasia.

Measles is an illness of universal distribution and great social impact. According to the WHO, the annual deaths due to this disease amount to more than a million children in the world. The objectives of this paper are to estimate the seroprevalence of titer of antibodies to measles in the population of 12 to 59 months of age in Mexico and identify the determinants of the immunity state. From the National Seroepidemiology Survey, 5,232 blood samples of children between 12 and 59 months of age, were analyzed, their blood samples were considered positive when the antibody titers were greater or equal to 1:4, tested by hemagglutination inhibition using sensitized erythrocytes. The National seroprevalence was 76.2 per cent. By age group, an increment in positive level was observed age increased. The seroprevalence was 56 per cent in children of 12 to 24 month and 82 per cent for children 48 to 59 month of age. The history of vaccination was obtained verbally; 62.5 per cent of seropositive didn't have vaccination history and 82.5 per cent were of those vaccinated were positive. By place of residence, at rural level (populations less than 2,500 inhabitants) 74 per cent positives, compared to 79 per cent in children of urban areas. All risk factor were significant, based on a univariate analysis, being the one with greatest risk those with negative vaccine history and children of one year of age. The efficiency of the vaccine estimation was of 63.6 per cent. Risk factors related to the vinculation of immunity protection to measles or seropositives were age, and verbal history of vaccination.

With the massive vaccination campaigns with the inactivated poliomyelitis vaccine starting in 1955 and its oral presentation in 1961, this disease has been controlled in many countries. However, wild polio virus is still transmitted in many developing countries. The study reported in this article had the objectives of estimating the prevalence of antibodies against polio for three types of virus (1, 2 and 3) in the population from 12 to 59 months of age in Mexico and determining the factors associated with the absence of immunity. One section of the National Seroepidemiology Survey (NSS), a study with a representative sample of the Mexican population, included the analysis of 5,260 blood samples for polio seropositivity. These samples were processed using the technique of plaque-reduction-neutralization, with the cut-off for positive titer values at 1:8. The national immunity levels reported for the three types of polio virus were: type 1 (89.8%); type 2 (97.6%); and type 3 (85.4%). The state with the lowest seroprevalence was Campeche, with 59.7 per cent, and the highest observed was Baja California Sur, with 93.0 per cent. The NSS also showed that the immunity level increases with age. There were some differences observed by place of residence; seroprevalences were higher in the urban areas (type one, 93.4%; type two, 98.5% and type three, 88.2%) than in the rural zones (86.6%, 96.8% and 82.9%, respectively). As expected, previous vaccination with three or more doses, referred verbally by the parent or guardian of the child, was associated with higher positivity.(ABSTRACT TRUNCATED AT 250 WORDS)