Perda de carga em microtubos e conectores utilizados em microaspersão

Este trabalho foi desenvolvido com o objetivo de ajustar equações que estimam a perda distribuída de carga em microtubos utilizados em microaspersão e a perda localizada de carga na passagem lateral do fluxo por meio dos conectores na linha lateral. A perda distribuída de carga foi determinada em quatro diâmetros de microtubos com nove a dez repetições para 15 vazões, por meio da aplicação do teorema de Bernoulli. O fator de atrito (f) foi estimado fixando-se o valor de m = 0,25 e calibrando-se o valor do parâmetro c (0,290). A perda localizada de carga foi determinada por diferença entre perda de carga no microtubo mais conector e perda de carga no microtubo. Dois modelos de conectores foram utilizados e caracterizados quanto ao diâmetro interno e dimensões. Uma aproximação matemática foi proposta para calcular a perda localizada de carga com base em coeficiente de carga cinética do conector (K'), que leva em consideração as dimensões do conector e do microtubo e independência das forças viscosas para Re > 5.000. As variações de vazão e de pressão entre os emissores situados nos extremos da linha lateral mostraram-se sensíveis à perda de carga na passagem lateral pelo conector mais a perda de carga no microtubo.

Efficiency of distinct data mining algorithms for classifying stress level in piglets from their vocalization

Among the challenges of pig farming in today's competitive market, there is factor of the product traceability that ensures, among many points, animal welfare. Vocalization is a valuable tool to identify situations of stress in pigs, and it can be used in welfare records for traceability. The objective of this work was to identify stress in piglets using vocalization, calling this stress on three levels: no stress, moderate stress, and acute stress. An experiment was conducted on a commercial farm in the municipality of Holambra, São Paulo State , where vocalizations of twenty piglets were recorded during the castration procedure, and separated into two groups: without anesthesia and local anesthesia with lidocaine base. For the recording of acoustic signals, a unidirectional microphone was connected to a digital recorder, in which signals were digitized at a frequency of 44,100 Hz. For evaluation of sound signals, Praat® software was used, and different data mining algorithms were applied using Weka® software. The selection of attributes improved model accuracy, and the best attribute selection was used by applying Wrapper method, while the best classification algorithms were the k-NN and Naive Bayes. According to the results, it was possible to classify the level of stress in pigs through their vocalization.

Development and validation of a genotype 3 recombinant protein-based immunoassay for hepatitis E virus serology in swine

Hepatitis E virus (HEV) is classified within the family Hepeviridae, genus Hepevirus. HEV genotype 3 (Gt3) infections are endemic in pigs in Western Europe and in North and South America and cause zoonotic infections in humans. Several serological assays to detect HEV antibodies in pigs have been developed, at first mainly based on HEV genotype 1 (Gt1) antigens. To develop a sensitive HEV Gt3 ELISA, a recombinant baculovirus expression product of HEV Gt3 open reading frame-2 was produced and coated onto polystyrene ELISA plates. After incubation of porcine sera, bound HEV antibodies were detected with anti-porcine anti-IgG and anti-IgM conjugates. For primary estimation of sensitivity and specificity of the assay, sets of sera were used from pigs experimentally infected with HEV Gt3. For further validation of the assay and to set the cutoff value, a batch of 1100 pig sera was used. All pig sera were tested using the developed HEV Gt3 assay and two other serologic assays based on HEV Gt1 antigens. Since there is no gold standard available for HEV antibody testing, further validation and a definite setting of the cutoff of the developed HEV Gt3 assay were performed using a statistical approach based on Bayes' theorem. The developed and validated HEV antibody assay showed effective detection of HEV-specific antibodies. This assay can contribute to an improved detection of HEV antibodies and enable more reliable estimates of the prevalence of HEV Gt3 in swine in different regions.