Seasonal effects on semen and testosterone in zebu and taurine bulls

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cover crop termination timing on rice crop production in a no-till system

Measuring shikimic acid accumulation in response to glyphosate applications can be a rapid and accurate way to quantify and predict glyphosate-induced damage to sensitive plants. The objective of this paper was to evaluate the effect of cover crop termination timing by glyphosate application on rice (Oryza sativa L.) yield in a no-till system. A factorial experiment, arranged in a split-plot design, was conducted for 2 yr. Treatments consisted of cover crops (main plots) and timed herbicide applications (subplots) to these cover crops (30, 20, 10, and 0 d before rice planting). There was a decrease in rice yield from 2866 kg ha-1 to 2322 kg ha-1 when the herbicide was applied closer to the rice planting day. Glyphosate application on cover crops increased shikimate concentrations in rice seedlings cultivated under palisade grass (Brachiaria brizantha), signal grass (B. ruziziensis), guinea grass (Panicum maximum), and weedy fallow (spontaneous vegetation) but not under millet (Pennisetum glaucum), which behaved similarly to the control (clean fallow, no glyphosate application). Glyphosate applications in the timing intervals used were associated with stress in the rice plants, and this association increased if cover crops took longer to completely dry and if higher amounts of biomass were produced. Millet, as a cover crop, allowed the highest seedling dry matter for upland rice and the highest rice yield. Our results suggest that using millet as a cover crop, with glyphosate application far from upland rice planting day (10 d or more), was the best option for upland rice under a no-tillage system. © Crop Science Society of America.

Danos em sementes de milho em função do mecanismo dosador de semeadora-adubadora

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uso de sub-produtos da fabricação de carvão vegetal na formação do porta-enxerto limoeiro 'cravo' em ambiente protegido

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Processamento semissólido de liga hipoeutética AlSi reforçada com Al203

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Respostas do capim-tifton 85 a doses de nitrogênio associadas a doses e fontes de boro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo e desenvolvimento do índice potencial de impacto de descargas atmosféricas em linhas de transmissão

Pós-graduação em Engenharia Mecânica - FEG

Application of Factorial Design Experiments to the Development of a Disposable Amperometric DNA Biosensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Optimization of an amperometric biosensor for the detection of hepatitis C virus using fractional factorial designs

Fractional factorial design and factorial with center point design were applied to the development of an amperometric biosensor for the detection of the hepatitis C virus. Biomolecules were immobilized by adsorption on graphite electrodes modified with siloxane-poly(propyleneoxide) hybrid matrix prepared using the sol-gel method. Several parameters were optimized, such as the streptavidin concentration at 0.01 mg mL(-1) and 1.0% bovine serum albumin, the incubation time of the electrodes in the complementary DNA solution for 30 minutes and a 1: 1500 dilution of the avidin-peroxidase conjugate, among others. The application of chemometric studies has been efficient, since the best conditions have been established with a restricted number of experiments, indicating the influence of different factors on the system.

A useful empirical bayesian method to analyse industrial data from saturated factorial designs

The use of saturated two-level designs is very popular, especially in industrial applications where the cost of experiments is too high. Standard classical approaches are not appropriate to analyze data from saturated designs, since we could only get the estimates of the main factor effects and we would not have degrees of freedom to estimate the variance of the error. In this paper, we propose the use of empirical Bayesian procedures to get inferences for data obtained from saturated designs. The proposed methodology is illustrated assuming a simulated data set. © 2013 Growing Science Ltd. All rights reserved.

Efeito da Proteína Bruta e de Diferentes Balanços Eletrolíticos das Dietas Sobre o Desempenho de Frangos no Período Inicial

Foram realizados dois experimentos utilizando-se 520 pintos machos de um dia para avaliar o efeito da proteína bruta (PB) e do balanço eletrolítico (Na + K- Cl) sobre o desempenho de frangos de corte no período inicial. O Experimento I (1 a 7 dias de idade das aves) foi realizado em baterias, utilizando-se 160 pintos machos Cobb, no Experimento II (1 a 21 dias) foram utilizados 360 pintos machos Aviam Farms que foram alojados em um galpão experimental dividido em box. Nos dois experimentos as aves foram aquecidas com lâmpadas infravermelhas e receberam água e ração à vontade. O delineamento foi inteiramente casualizado, em um esquema fatorial 2 x 2 (PB x balanço eletrolítico - BE), com 5 repetições e 8 aves por unidade experimental no Experimento I e fatorial 2 x 3 (PB x BE), com 3 repetições e 20 aves por unidade experimental no Experimento II. Os níveis de K foram mantidos constantes, oscilando-se o Na e o Cl para obter os balanços eletrolíticos desejados. Os parâmetro de desempenho (consumo de ração, ganho de peso e conversão alimentar) foram analisados no final de cada fase experimental. em ambos os experimentos não houve interação entre PB e BE. Os níveis de 21,0 e 23,5% de PB não afetaram o desempenho das aves. em dietas pré-iniciais e iniciais o melhor desempenho foi atingido com 260 mEq/kg.

Multistratum response surface designs

Response surface designs are usually described as if the treatments have been completely randomized to the experimental units. However, in practice there is often a structure to the units, implying the need for blocking. If, in addition, some factors are more difficult to vary between units than others, a multistratum structure arises naturally. We present a general strategy for constructing response surface designs in multistratum unit structures. Designs are constructed stratum by stratum, starting in the highest stratum. In each stratum a prespecified treatment set for the factors applied in that stratum is arranged to be nearly orthogonal to the units in the higher strata, allowing-for all the effects that have to be estimated. Three examples are given to show the applicability of the method and are also used to check the relationship of the final design to the choice of treatment set. Finally, some practical considerations in randomization are discussed.

Row-column response surface designs

Factorial experiments are widely used in industry to investigate the effects of process factors on quality response variables. Many food processes, for example, are not only subject to variation between days, but also between different times of the day. Removing this variation using blocking factors leads to row-column designs. In this paper, an algorithm is described for constructing factorial row-column designs when the factors are quantitative, and the data are to be analysed by fitting a polynomial model. The row-column designs are constructed using an iterative interchange search, where interchanges that result in an improvement in the weighted mean of the efficiency factors corresponding to the parameters of interest are accepted. Some examples illustrating the performance of the algorithm are given.

Difference variance dispersion graphs for comparing response surface designs with applications in food technology

Variance dispersion graphs have become a popular tool in aiding the choice of a response surface design. Often differences in response from some particular point, such as the expected position of the optimum or standard operating conditions, are more important than the response itself. We describe two examples from food technology. In the first, an experiment was conducted to find the levels of three factors which optimized the yield of valuable products enzymatically synthesized from sugars and to discover how the yield changed as the levels of the factors were changed from the optimum. In the second example, an experiment was conducted on a mixing process for pastry dough to discover how three factors affected a number of properties of the pastry, with a view to using these factors to control the process. We introduce the difference variance dispersion graph (DVDG) to help in the choice of a design in these circumstances. The DVDG for blocked designs is developed and the examples are used to show how the DVDG can be used in practice. In both examples a design was chosen by using the DVDG, as well as other properties, and the experiments were conducted and produced results that were useful to the experimenters. In both cases the conclusions were drawn partly by comparing responses at different points on the response surface.

Optimum design of experiments for statistical inference

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)