Modelación estocástica de la variabilidad anual e interanual de la humedad del suelo en Colombia bajo diferente cobertura vegetal.

Se estudia la dinámica temporal de la humedad de suelo y su función de distribución de probabilidades [FDP], mediante un modelo estocástico basado en el balance de agua en un punto. Se derivan las características cualitativas y cuantitativas de la humedad del suelo en la zona cafetera de Colombia y su variabilidad durante los ciclos anual e interanuial de precipitación; y se estudian las diferencias de estas respuestas para cobertura de bosque, café al sol y café a la sombra. Se estudia el efecto de amplificación del fenómeno ENSO en términos de la variabilidad de la FDP de la humedad del suelo

Asociación entre el fenómeno El Niño y las anomalías de humedad del suelo y del índice "NDVI" en Colombia.

Se muestra que el fenómeno El Niño/Oscilación del Sur amplifica fuertemente las anomalías negativas de humedad de suelo y NDVI (Indice de Vegetación de Diferencias Normalizado) en Colombia. La evidencia muestra la alta correspondencia de la variabilidad anual e interanual de los datos de humedad volumetrica del suelo (promedios de 10 dias), para el periodo 1997-1999, cuando se presentaron eventos fuertes de El Niño y La Niña en el Oceano Pacífico Tropical

Un modelo estocástico para la humedad del suelo bajo diferentes coberturas vegetales en la región cafetera de Colombia.

Se estudia la dinámica temporal de la humedad de suelo y su Función de Distribución de Probabilidades (FDP), mediante un modelo estocástico basado en el balance de agua en un punto. Se derivan las características cualitativas y cuantitativas de la humedad del suelo en la zona cafetera de Colombia y su variabilidad durante los ciclos anual e interanual de precipitación; y se estudian las diferencias de estas respuestas para cobertura de bosque, café al sol café a la sombra

Canopy structure and theoretical coefficient of extinction in genotypes of arabic coffee in Colombia

The canopy structure has a marked effect on the interception of the solar radiation and the plant photosynthesis, in addition to other processes that in their group, are the result of the plant-environment interaction. The present research was carried out at the Central Station Naranjal of CENICAFÉ (National Coffee Research Center - Chinchiná, Caldas, Colombia) in 25 genotypes of Coffea arabica L. which were divided in two groups. The first one with tall aspect plants (3.6 years old) and the second one, with short plant aspect (2.6 years old) both planted in a density of 5000 plants.ha-1. The leaf and branches angles distribution in the canopy were characterized in the different assessed genotypes, also the theoretical extinction coefficients for direct and diffuse solar radiation were estimated. In genotypes of high aspect, the plagiophile and spherical leaf distribution predominated, as in the ones of short aspect the planophile did. The parameter x, represents the ellipsoidal distribution of the leaf angles, which varied between 0.09 and 2.21 for genotypes of high aspect (vertical and spherical) and between 1.90 and 3.98 for the ones of short aspect (horizontal). The theoretical coefficients of extinction for the direct radiation derived of the parameter x varied between 0.63 to 0.83 for the group of high aspect, and the short one, showed values between 0.84 to 0.93, for the diffuse radiation the coefficients showed the same trend but with minor values. As regards the inclination angles of the branches was characterized for being planophile predominant

Estructura del dosel y coeficientes de extinción teóricos en genotipos de café arábico en Colombia

La estructura del dosel tiene un marcado efecto sobre la interceptación de la radiación y la fotosíntesis de la planta, además de otros procesos. El estudio se llevó a cabo en la Estación Central Naranjal de CENICAFÉ (Centro Nacional de Investigaciones de Café – Chinchiná, Caldas, Colombia) sobre 25 genotipos de Coffea arabica L., divididos en dos grupos. El primer grupo, con plantas de porte alto (3.6 años) y el segundo con plantas de porte bajo (2.6 años), ambos sembrados a una densidad de 5000 plantas.ha-1. La distribución de los ángulos de las hojas y las ramas en el dosel se caracterizaron en los diferentes genotipos evaluados, así mismo los coeficientes de extinción teóricos de la radiación solar directa y difusa fueron estimados. En los genotipos de porte alto predominaron las distribuciones foliares plagiófila y esférica, mientras que en los de porte bajo fue la planófila. El parámetro x representa a la distribución elipsoidal de los ángulos foliares, este valor varió entre 0.09 y 2.21 para los genotipos de porte alto (verticales y esféricos) y entre 1.90 y 3.98 para los de porte bajo (horizontales). Los coeficientes de extinción teóricos para la radiación directa derivados del parámetro x variaron entre 0.63 a 0.83 para el grupo de porte alto, mientras que en el porte bajo mostraron valores entre 0.84 a 0.93. Para la radiación difusa, los coeficientes presentaron la misma tendencia, pero con valores menores. En cuanto al ángulo de inclinación de las ramas, se caracterizó por ser predominantemente planófilo

EFFECTS OF DAYLENGTH AND SOIL HUMIDITY ON THE FLOWERING OF COFFEE COFFEA ARABICA L. IN COLOMBIA EFECTO DE LA DURACIÓN DEL DÍA Y LA HUMEDAD DEL SUELO SOBRE LA FLORACIÓN DEL CAFETO COFFEA ARABICA L. EN COLOMBIA

Coffee flowering data were analyzed in order to explore the effect of two environmental variables that have been considered relevant for this process. Pre-anthesis stage flowers were counted in coffee leaf-rust resistant crops at eight experimental stations (between 2°N and 11°N). Likewise, climatic data were taken to generate a humidity soil index, whereas day longitude data were taken from the Smithsonian Meteorological Tables. Flowering data were compared with a sunshine index to understand better the effect of light on flowering. This data (flowering, soil humidity index and day length) were expressed in a monthly scale and analyzed using linear regression and cross-correlation functions. The main results show that there is a significant correlation between short days and high flowerings, whereas soil humidity (dry months) are related to the phenomenon, but to a lesser extent.Con el objetivo de entender el efecto de las variables ambientales sobre el cultivo del café, se analizaron los datos de floración para explorar el efecto de dos variables que han sido reportadas como importantes en la floración de esta especie. Se contaron flores en etapa de pre-antesis en cafetales sembrados con variedades resistentes a roya en ocho estaciones experimentales entre 2°N y 11°N. A su vez, fueron tomados datos del clima para generar un índice de humedad del suelo, mientras que los datos de longitud del día se tomaron de las tablas meteorológicas del Smithsonian; para entender mejor el efecto de la luz sobre la floración, fueron comparados los datos de floración y un índice de brillo solar. Estos datos (floración, índice de humedad del suelo y longitud del día) se expresaron en escala mensual y se analizaron utilizando regresión lineal y funciones de correlación cruzada. Los resultados muestran que hay una correlación importante entre días cortos y altas floraciones, mientras que la humedad del suelo (meses secos) tienen una relación con el fenómeno, pero con menor correlación

Evaluation of four degree-day estimation methods in eight Colombian coffee-growing areas

Methods for estimating the accumulation of degree-days based on maximum and minimum temperatures are commonly used to determine relationships or to adjust phenological models based on the “physiological time”. Degree-days are obtained indirectly by these methods, given that information is not generally available on hourly or shorter time scales, due to the type of equipment used to record data or a data loss in historical time series. To compare the performance of such methods, degree-days were estimated with four indirect techniques in eight Colombian locations during one year. Each indirect technique was evaluated in comparison to the numerical integration method by the trapezoidal rule (reference method) using temperatures recorded every five minutes. Based on the percent bias, the methods proposed by Arnold, Ometto and Snyder tend to overestimate thermal time, whereas the Villa Nova method underestimates this time. The use of the different methods depends on the information available for the estimation of the study variable

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially