Resumen -El objetivo de este trabajo fue utilizar el análisis de componentes principales y de semivarianza para seleccionar variables físicas que explicaran la variabilidad de un suelo aluvial, y establecer el comportamiento espacial de las variables seleccionadas, con el fin de definir técnicamente la localización de parcelas experimentales para estudiar los efectos de la abrasividad del suelo sobre el desgaste de herramientas agrícolas. Las pruebas de campo se realizaron en 2008, en un lote plano de 6.000 m 2 con suelos de textura media a pesada (Vertic Haplustepts). Se hizo un muestreo intensivo en cuadrícula de 10x14 m. Las variables que mayor peso tuvieron en los tres primeros componentes principales fueron los contenidos de limo, arena fina y media, gravilla media, la humedad a capacidad de campo y el coeficiente higroscópico. A excepción de la arena media y la capacidad de campo, las demás propiedades presentaron alta dependencia espacial y su distribución mostró que en el lote experimental se encuentran tres sectores de acumulación diferencial de limo y de arena fina. La combinación de los análisis de componentes principales y geoestadística permitió definir las propiedades del suelo involucradas en el desgaste de herramientas, su patrón espacial y la manera más adecuada de distribuir parcelas experimentales, para estudiar la abrasividad del suelo.Términos para indexación: abrasividad, análisis de tendencia, componentes principales, dependencia espacial, geoestadística, textura del suelo. Physical variables that explain alluvial soil variability and their spatial behaviorAbstract -The objective of this work was to use the principal component and semivariance analyses to select physical variables that could explain the variability of an alluvial soil, in order to establish the spatial behavior of the chosen variables so that the location of experimental plots could be technically defined to study the abrasiveness effect on the wearing away of farm equipment. Field tests were performed in 2008, on a 6,000 m 2 flat lot with medium to heavy soil texture (Vertic Haplustepts). An intensive sampling was done in a grid of 10x14 m. The variables which had the most weight on the first three principal components were the contents of silt, fine and intermediate sand, intermediate gravel, soil moisture at field capacity, and the hygroscopic coefficient. Except for the half sand and the field capacity, the other properties showed a high spatial dependence, and their distribution showed that in the experimental plot there are three sectors of differential accumulation of silt and fine sand. The combination of principal component analysis and geostatistics allowed for defining the soil properties involved in the wear of tools, their spatial pattern and the most appropriate way of distributing plots to study soil abrasiveness.

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The harvest is one of the most important activities in coffee crops; on the one hand, it provides employment opportunities for a large group of rural workers and on the other, it supplies mature fruits for the production of high quality coffee. In the present study, a device was designed and evaluated to assist in manual coffee harvesting, called Alfa, which employs a three-toothed blade beater, a DC motor powered by dry batteries and a system for receiving detached fruits. The research proceeded in two phases; in the first, the device was designed and built; in the second, an evaluation was carried out by using traditional manual collection as a comparison. The evaluations were developed in four locations: three experimental stations of Cenicafé and one private property. The variables studied were: number of fruits left on the ground after harvest, percentage of immature coffee in the harvested mass and yield. The device presented an operating time of four days without recharging, a weight less than four kg and an absence of technical failures; the operators had no problems with its use; and, in addition, it was possible to increase the yield of the operators by almost 70%; the percentage of immature coffee was between 4.5% and 3% and losses were between one and 19 fruits per site.

Background Longitudinal assessment and reversibility of changes in the pulmonary function tests in the post-acute phase of COVID-19 across the whole spectrum of severity of infection is needed to understand the long-term burden of the disease. Methods This was a prospective cohort of symptomatic patients with a positive SARS-CoV-2 (molecular or antigenic) test. Participants were divided based on infection severity at baseline as mildly-ill (B1), moderately-ill (B2), severely-ill (B3), critically-ill (B4) (Fig.1). Follow-up consisted of 4 visits: within 7 days from discharge (BL), and at months 1 (M1), 3 (M3), and 6(M6). We report findings up to M3 for participants enrolled August 2021- March 2022. Pulmonary function capacity was assessed with carbon monoxide diffusing capacity (DLCO), spirometry, and 6-minute walk test (6MWT). A DLCO< 80% was considered abnormal and reverted if >80% at follow-up visits. Study population divided by severity of infection Results Out of 206 eligible participants, 110 were enrolled, of which 96 (87%%), 79 (72%), and 52(47.2%) were evaluated at BL, M1, and M3, respectively (Fig.2). Most (67%) participants were male, median age was 37.5 years old (IQR: 28-46.3) and median body mass index was 26.7 (IQR:23.7-30.4). Regarding severity, 39 (41%) participants were classified as critically-ill (B4) at BL. No underlying comorbidities were reported among 63 (66%) participants, while diabetes type 2 (11%), asthma (7%) prior pulmonary tuberculosis (6%) and hypertension (5%) where the most frequent comorbidities overall; 17 (18%) reported smoking exposure. There were significant differences accross severity groups for sex, age, absence of comorbidities, and dyspnea during the acute phase of COVID-19 (Tab.1). At Of the 88 (92%) participants that underwent the pulmonary function tests at BL: 49 (56%) had DLCO < 80% with a tendency to revert across B1-B4 groups at month 3 (Fig.3). Spirometry parameters (Forced Vital Capacity, Forced Expiratory Volume 1, Peak Expiratory Flow) and distance walked on 6MWT were different across groups. Flowchart of the study population Demographics of study population stratified by groups of severity Median DLCO adjusted for hemoglobin value at baseline, month 1 and month 3 visits stratified by groups of severity of infection. Conclusion Abnormal DLCO tended to increase and revert to values greater than 80% in the 3-month follow-up period of patients recovered from SARS-CoV-2 infection across severity groups. Disclosures All Authors: No reported disclosures.