Development of an Electronic System for Field-Scale Geomorphometric Measurements

Terrain attributes are among the most studied soil characteristics. Although important, in only a few areas are topographic features mapped at the field-scale level. These features play an important role in assessing the crop production potential and erosion susceptibility of agricultural fields. Therefore high-resolution mapping of terrain attributes are vital to a better management of production fields. Today, terrain attributes are derived from elevation measurement.A more direct form of measurement was developed by Rowe and Spencer (1976), pitch and roll angles were used to derive slope gradient and vehicle attitude. Yang (1997) related vehicle attitude to slope aspect. The existing mathematical models are difficult to implement with today’s low-cost micro-controllers because of existing trigonometric functions. Research conducted at the Biosystems Department of The University of Tennessee focused on the simplification of existing models and on the development of an electronic system to test two sensing techniques in dual-axial rotational measurement of a roving vehicle: a clinometer and an accelerometer. Tests were conducted in a field with a widely varying topography located on the Blount Experiment Research Unit, by mounting the electronic monitoring system on an ATV. Elevation data measured with a RTK-GPS were used to generate an accurate elevation map. Terrain attributes were calculated in 3 spatial resolutions: 4, 16, and 100 m2.Simplification of the mathematical models relating pitch and roll angles to terrain attributes is possible because of the existing limitations on slope gradient of arable lands. Results obtained during field tests show that slope measurement accuracy varied according to spatial resolutions. The density of points used in the calculation of the terrain attributes also contributes to measurement accuracy. In general, mean absolute error (MAE) were less than 1° for both sensors in all resolutions tested. Data collected from pitch and roll sensors can also be used to detect field elevation changes.In conclusion, it is possible to rely on measurements of vehicle axial rotation for the computation of field-scale terrain attributes. The sensing techniques tested were successfully used in these measurements. The application of simplified models to derive terrain measurements is possible due to the existing slope gradient limitation of arable lands. It is possible to describe terrain attributes in a scale similar to order I soil maps using the proposed electronic system and models. The system can also be used to pinpoint locations of elevation differences in the field

Site-specific applications of nitrogen in corn based on yield potential

Burdened by high production costs and increased environmental concerns, today\u27s farmers are looking for new technologies that can help optimize their production efficiency. Site-specific farming is a technique to describe what some are calling the next major revolution in production agriculture which has the potential to address many of these concerns. During the 1994 season, an experiment was conducted to document site-specific yield response of corn for different application rates of nitrogen fertilizer within soils with varying yield potentials. To accomplish this task, new technologies such as Global Positioning System (GPS), Geographic Information Systems (GIS), grain yield monitoring, and variable rate control were integrated into a overall system. A 22-acre no-till production corn field located in Milan, Tennessee was selected for this study. Prior to planting, an extensive soil survey was conducted and the field was classified based on varying levels of yield potential. Five different application rates of nitrogen were applied on the field using a variable rate applicator controlled by a laptop PC with control information being received in real-time from a GPS receiver and digital application map. Soil nutrient samples, leaf nitrogen samples, and plant population samples were collected through the season. The GIS software in conjunction with the GPS receiver proved to be an effective method for managing spatially related information. Results indicate that variable rate application of nitrogen based on site-specific soil types within a field has the potential to increase the production efficiency for producers

New evidences on the diagnostic value of indirect immunofluorescence test and delayed hypersensitivity skin test in human infection by Leishmania (L ) infantum chagasi in the Amazon, Brazil

Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil / Universidade Federal do Pará. Núcleo de Medicina Tropical. Belém, Pará, Brasil.Estudo prospectivo realizado no período de maio/2006-setembro/2008, numa coorte de 1.099 indivíduos, ambos os sexos, com idades de 1 a 84 anos (média 24,4 anos), residente em área endêmica de leishmaniose visceral americana (LVA) no Município de Cametá, Pará, Brasil, objetivando analisar a prevalência e a incidência da infecção humana por Leishmania (L.) infantum chagasi, assim como a dinâmica da evolução dos seus perfis clínico-imunológicos previamente definidos: 1. Infecção assintomática (IA); 2. Infecção sintomática (IS=LVA); 3. Infecção subclínica oligossintomática (ISO); 4. Infecção subclínica resistente (ISR); e 5. Infecção inicial indeterminada (III). O diagnóstico da infecção baseou-se no uso simultâneo da reação de imunofluorescência indireta (RIFI) e reação intradérmica de hipersensibilidade tardia. Um total de 304 casos da infecção foi diagnosticado no período do estudo (187 na prevalência e 117 na incidência), gerando prevalência acumulada de 27,6%, cuja distribuição no âmbito dos perfis clínico-imunológicos foi da seguinte ordem: IA 51,6%, III 22,4%, ISR 20,1%, ISO 4,3% e, IS (=LVA) 1,6%. Com base na dinâmica da infecção, o principal achado recaiu no perfil III, que teve papel fundamental na evolução da infecção, dirigindo-a ora para o pólo imunológico de resistência, perfis ISR (21 casos - 30,8%) e IA (30 casos - 44,1%), ora para o polo imunológico de susceptibilidade, perfil IS (um caso - 1,5%); além destes, 16 casos mantiveram o perfil III até o fim do estudo. Concluiu-se que esta abordagem diagnóstica pode ajudar no monitoramento da infecção na área endêmica, visando, principalmente, prevenir a morbidade da LVA, assim como reduzir o tempo e despesas com o tratamento.This is a prospective study on a cohort of 1099 individuals of both genders, aged 1-84 years (mean 24.4 years), living in an endemic area of American visceral leishmaniasis (AVL) in the Municipality of Cametá, Brazil, from May 2006 to September 2008. It aimed to analyze the prevalence and incidence rates of human infection by Leishmania (L.) infantum chagasi, as well as the evolutional process of its previously defined clinical and immunological profiles: 1. Asymptomatic infection (AI); 2. Symptomatic infection (SI = AVL); 3. Subclinical oligosymptomatic infection (SOI); 4. Subclinical resistant infection (SRI); and 5. Indeterminate initial infection (III). The diagnosis was based on the simultaneous use of indirect immunofluorescence assay (IFA) and delayed hypersensitivity skin test. A total of 304 cases of infection were diagnosed during the period studied (187 for prevalence and 117 for incidence), generating an accumulated prevalence rate of 27.6%. The distribution regarding their clinical and immunological profiles presented the following order: AI 51.6%; III 22.4 %; SRI 20.1%; SOI 4.3%; and SI (= AVL) 1.6%. Based on the dynamics of the infection, the main discovery was about the III profile, which had an instrumental role in its evolution, directing it either to the resistant immunological pole – SRI (21 cases - 30.8%) and AI (30 cases - 44.1 %) profiles – or to the susceptible immunological pole – SI (1 case - 1.5%) profile. In addition, 16 cases remained within the III profile until the end of the study. It was concluded that this diagnostic approach can help monitor the infection in endemic areas, aiming mainly at preventing morbidity caused by AVL, and reducing the treatment time and expenses

Novas evidências sobre o valor diagnóstico da reação de imunofluorescência indireta e reação intradérmica de hipersensibilidade tardia na infecção humana por Leishmania (L.) infantum chagasi na Amazônia, Brasil

itemItensArtigos publicados na "Revista Pan-Americana de Saúde"