A proposal with low cost for cathode ray experiments

This paper presents a proposal for the adaptation of one of the experiments on the nature of the cathod rays performed at the end of the 19th century, specifically the one presented in textbooks and scientific dissemination as "the Thomson experiment" for the calculation of charge /mass ratio of the electron. Our proposal uses materials at a lower cost than experiment kits available on the market and presents a detailed description of its construction and operation, and contributes in several respects as a solution to some of the reasons related to the low utilization of experiments in science classes: the high cost materials and equipment, the lack of laboratories and the lack of ability of teachers. The elaboration of the experimental apparatus is also accompanied by the mathematical development necessary for its use and the indication of the various physical phenomena that can be treated in parallel with its implementation. With the experimental adaptation, we were able to measure and calculate the magnetic field to which the electrons are subjected inside a cathode ray tube, the potential difference between cathode and anode in the tube (electron acceleration voltage), the magnetic deflection that the electrons undergo, and to a good approximation the speed of translation of the electrons and the charge/ mass ratio of these particles

Uso de extensores flexíveis na derriça em lavouras de café primeira safra

The coffee harvest of the first crop can be benefited by the use of rubber extenders at the end of the stems. This because their malleable constitution acquires oscillatory motion increasing the stem contact area with the fruits. However, the coffee varieties have big morphological and physiological differences that can influence the mechanical harvesting. This study had a goal to test two of coffee harvesters (conventional and adapted to the harvest of the first crop plantations) in the absence and presence of rubber extenders in two cultivars (Catuaí Vermelho IAC 144 and Tupi IAC 1669-33). The design was randomized blocks in five plants per plot. Evaluated the amount of fallen coffee, remaining harvested, picked and operational defoliation. Evaluated the amount of fallen coffee, remaining harvested and operational defoliation. There was obtained that the use of rubber extenders increases the amount of coffee collected in 16.6%. The first crop coffee harvest should be made with harvester adapted to this situation. The Cultivar Tupi IAC 1669-33 has high difficulty to be mechanically harvested the first crop, should be taken with two mechanized operations.A colheita do café de primeira safra pode ser beneficiada pela utilização de extensores de borracha na extremidade das hastes. Isto pois sua constituição maleável adquire movimento oscilatório aumentando a área de contato da haste com os frutos. No entanto, as cultivares de café apresentam grandes diferenças morfo-fisiológicas que podem influenciar na colheita mecanizada. Objetivou-se testar duas colhedoras de café (convencional e adaptada para a colheita de lavouras de primeira safra), na ausência e presença de extensores de borracha, em duas cultivares (Catuaí Vermelho IAC 144 e Tupi). O delineamento foi de blocos ao acaso, em parcelas de cinco plantas. Avaliou-se a quantidade de café caído, remanescente, colhido, derriçado e desfolha operacional. Obteve-se que a utilização de extensores de borracha eleva a quantidade de café colhido em 16,6%. A colheita do café de primeira safra deve ser procedida com colhedora adaptadas para tal situação. A Cultivar Tupi apresenta elevada dificuldade em ser colhida mecanicamente na primeira safra, devendo ser colhida com duas operações mecanizadas

ANÁLISE MORFOLÓGICA DOS PROCESSOS PATOLÓGICOS GERAIS EM RINS DE RATOS OBESOS E SUA RELAÇÃO COM O EXERCÍCIO FÍSICO

The objective of the study was to compare the morphological findings, quantify the inflammation and renal fibrosis in obese rats submitted to physical exercise. Male Wistar rats were used. Control animals were fed standard feed and tap water, and the obese were fed a hyperlipidic diet. These animals were submitted to intermittent training, where the movement of complete extension of the paw was performed, lifting a load positioned at the back of the vest. The animals' kidneys were collected to evaluate the findings. Regarding the histopathological analysis, no general pathological processes were evidenced. When the fibrosis quantification was performed, no significant results were observed between the groups. It was concluded that no general pathological processes were observed in the kidneys of obese rats and their relationship with physical exercise. In this way, it is suggested to carry out new studies with longer protocols in order to better elucidate the results.   KEYWORDS: Obesity, Kidney, Inflammation, Fibrosis, Exercise.O objetivo do estudo foi comparar os achados morfológicos, quantificar a inflamação e fibrose renal em ratos obesos submetidos ao exercício físico. Foram utilizados 56 ratos machos Wistar. Os animais controles foram alimentados com ração padrão e água de torneira, e os obesos por uma dieta hiperlipídica. Esses animaisforam submetidos ao treinamento intermitente, onde se realizou o movimento de extensão completa da pata, levantando uma carga posicionada na parte posterior do colete. Foram coletados os rins dos animais para avaliar os achados. Com relação à análise histopatológica, não foram evidenciados processos patológicos gerais. Ao ser realizada a quantificação de fibrose, não foram evidenciados resultados significativos entre os grupos. Conclui-se que não foram evidenciados processos patológicos gerais em rins de ratos obesos e sua relação com o exercício físico. Desta forma, é sugerida a realização de novos estudos com protocolos mais longos a fim de elucidar melhor os resultados. Palavras-chaves: Obesidade, rim, Inflamação, fibrose, exercício

Uma proposta de baixo custo para experimentos com raios catódicos

This paper presents a proposal for the adaptation of one of the experiments on the nature of the cathod rays performed at the end of the 19th century, specifically the one presented in textbooks and scientific dissemination as "the Thomson experiment" for the calculation of charge /mass ratio of the electron. Our proposal uses materials at a lower cost than experiment kits available on the market and presents a detailed description of its construction and operation, and contributes in several respects as a solution to some of the reasons related to the low utilization of experiments in science classes: the high cost materials and equipment, the lack of laboratories and the lack of ability of teachers. The elaboration of the experimental apparatus is also accompanied by the mathematical development necessary for its use and the indication of the various physical phenomena that can be treated in parallel with its implementation. With the experimental adaptation, we were able to measure and calculate the magnetic field to which the electrons are subjected inside a cathode ray tube, the potential difference between cathode and anode in the tube (electron acceleration voltage), the magnetic deflection that the electrons undergo, and to a good approximation the speed of translation of the electrons and the charge/ mass ratio of these particles.Este trabalho apresenta uma proposta de adaptação de um dos experimentos sobre a natureza dos raios catódicos realizado ao final do século XIX, especificamente, aquele apresentado em livros didáticos e de divulgação científica como “o experimento de Thomson” para o cálculo da relação carga/massa do elétron. Nossa proposta utiliza materiais com custos inferiores aos de kits de experimentos disponíveis no mercado internacional e apresenta uma descrição pormenorizada da sua construção e operação, concorrendo, em vários aspectos, como solução para alguns dos motivos relacionados à pouca utilização dos experimentos nas aulas de ciências: o custo elevado dos materiais e dos equipamentos, a falta de laboratórios e a falta de habilidade dos professores. A elaboração do aparato experimental é ainda acompanhada do desenvolvimento matemático necessário à sua utilização e da indicação dos vários fenômenos físicos que podem ser tratados paralelamente à sua implementação. Com a adaptação experimental, fomos capazes de medir e calcular o campo magnético a que os elétrons são submetidos no interior de um tubo de raios catódicos, a diferença de potencial entre catodo e anodo no tubo (tensão de aceleração dos elétrons), a deflexão magnética que os elétrons sofrem, e, com uma boa aproximação, a velocidade de translação dos elétrons e a relação carga/massa dessas partículas

Geomorphometric tool associated with soil types and properties spatial variability at watersheds under tropical conditions

ABSTRACT The application of quantitative methods to digital soil and geomorphological mapping is becoming an increasing trend. One of these methods, Geomorphons, was developed to identify the ten most common landforms based on digital elevation models. This study aimed to make a quantitative assessment of the relationships between Geomorphons units, determined at three spatial resolutions and nine radii, and soil types and properties of two watersheds with different soil-landscape relationships in Brazil to help soil surveying and mapping under tropical conditions. The study was conducted at Lavrinha Creek (LCW) and Marcela Creek (MCW) watersheds, located in the state of Minas Gerais, Brazil. Spatial resolutions of 10, 20 and 30 m were the basis for generating Geomorphons at 9 radii of calculation for the watersheds. They were overlapped to detailed soil maps of the watersheds and a chi-square test was carried out to assess their relationship with soil types. Observation points were compared with the most highly correlated Geomorphons to also assess relationships with soil properties. Geomorphons with resolution of 30-m and radii of 20 and 50 cells, respectively for LCW and MCW, were more highly correlated with the variability of soil types, in accordance with the terrain features of these watersheds. The majority of observation points for each soil type was located in the same Geomorphon unit that was dominant when analyzing soil maps. There was less variability in soil properties between Geomorphon units, which was probably due to the highly weathered-leached stage of soils. Geomorphons can help to improve soil maps in tropical conditions when assessing soil variability due to its high correlation with tropical soil types variability