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101.
Aline Schäfer Rodrigues Silva Markus Noack Dirk Schlabing Silke Wieprecht 《Journal of Soils and Sediments》2018,18(10):3070-3081
Purpose
The critical shear stress of cohesive and mixed cohesive/non-cohesive sediments is affected by multiple interacting physical, chemical and biological parameters. There are various mathematical approaches in the scientific literature for computing critical shear stress. However, processes that influence sediment stability are still not fully understood, and available formulas differ considerably. These discrepancies in the literature arise from random system behaviour (natural variability of the sediments), different definitions of the critical shear stress, different measurement techniques and different model frameworks (scope of the parameters, undisturbed versus artificial sediment samples). While analytical approaches fail to address the involved uncertainties, fuzzy logic-based models integrate uncertainty and imprecision.Materials and methods
With this in mind, a data-driven neuro-fuzzy model (ANFIS) was used to determine the critical shear stress based on sediment characteristics such as wet bulk density and grain size distribution. In order to select model predictors systematically, an automated stepwise regression algorithm was applied. The database for this analysis consisted of 447 measurements of the critical shear stress originating from 64 undisturbed sediment samples.Results and discussion
The study identified clay content as the primarily controlling variable for erosion resistance. Depending on the characteristics of the sampling location, the bulk density was also selected as a model predictor. In comparison to analytical models that are available in the scientific literature, the fuzzy model achieved higher correlation coefficients between measured and predicted data.Conclusions
The neuro-fuzzy-model includes uncertainties of input variables and their interactions directly. Thus, it provides a reliable method for the prediction of erosion thresholds of cohesive/non-cohesive mixtures. It was also shown that this approach requires fewer measured variables as well as fewer assumptions than the models it was compared to.102.
Autochthonous probiotic as growth promoter and immunomodulator for Astyanax bimaculatus cultured in water recirculation system 
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下载免费PDF全文 Andressa Vieira de Moraes Marina de Oliveira Pereira Klayton Natan Moraes Jorge P Rodrigues‐Soares Gabriel Fernandes Alves Jesus Adolfo Jatobá 《Aquaculture Research》2018,49(8):2808-2814
This work aimed to evaluate the probiotic Lactobacillus spp. in the microbiota of Astyanax bimaculatus reared in a water recirculation system. The experiment was randomized, using 800 postlarvae distributed into eight polyethylene containers, separated into two treatments, in quadruplicate: supplementation with Lactobacillus spp. (Probiotic) and no supplementation (Control). After 90 days of culture, 13 fish per container were anaesthetized. Three of these underwent microbiological evaluation, and haematological analyses were carried out on five. Immunological assessment was performed on another five fish. Zootechnical parameters were evaluated for all animals. In the microbiological evaluation, the probiotic group presented higher counts of lactic acid bacteria, but lower counts of Vibrio spp., Pseudomonas spp., and Staphylococcus spp., when compared with control. After haematological analysis, the supplemented group presented low haematimetric indices of Mean Corpuscular Haemoglobin Concentration and Mean Corpuscular Haemoglobin (MCHC and MCH, respectively) and higher amounts of total leucocytes, thrombocytes and circulating monocytes when compared with control. The immunological profile did not differ between treatments. In the zootechnical performance, probiotic group presented higher productivity, survival and apparent food efficiency when compared with control. Therefore, when Lactobacillus spp. was supplemented in the diet of A. bimaculatus, immunocompetence and the zootechnical performance of animals increased. 相似文献
103.
González-Wangüemert Mercedes Roggatz Christina C. Rodrigues Maria João Barreira Luísa da Silva Manuela Moreira Custódio Luísa 《International Aquatic Research》2018,10(4):361-373
International Aquatic Research - This work makes a comparative evaluation of the biochemical profile of three sea commercial cucumber species (Holothuria mammata, H. polii and H. tubulosa) caught... 相似文献
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105.
Roselene Nogueira Rodrigues Marcos Sidney Brito Oliveira Marcos Tavares-Dias 《Journal Of Applied Aquaculture》2018,30(1):29-38
Fish farming has grown rapidly in Brazil over the last two decades, due in part to the availability of water and species with potential for cultivation, such as Colossoma macropomum. This farmed fish, however, can be affected by parasitic infections with high mortality rates (>35%). The main objective of the present study was to describe the first occurrence of the Trypanosoma species in Colossoma macropomum, which occurred in fish cultured in the Brazilian Amazon region, as well as to morphologically characterize the trypomastigotes and the impact of these hemoparasites on the body condition of the hosts. The trypanosomes found in the blood of Colossoma macropomum were morphologically characterized by the size of the trypomastigote form, indicating the presence of only one morphotype. Of the 39 hosts examined from one fish farming, 41.0% were infected by Trypanosoma sp., with low levels of infection (mean blood density of 3.7/μL). The condition factor of the asymptomatic hosts was not affected by hemoparasitism. There was no correlation between the abundance of Trypanosoma sp. and the condition factor and size of the hosts. Finally, our understanding of host-parasite interactions and the detection of emerging diseases are fundamental for aquaculture. 相似文献
106.
Relationships between botanical composition,yield and forage quality of permanent grasslands over the first growth cycle 下载免费PDF全文
下载免费PDF全文 D. Andueza A. M. Rodrigues F. Picard N. Rossignol R. Baumont U. Cecato A. Farruggia 《Grass and Forage Science》2016,71(3):366-378
This study examined the relationships between botanical composition and forage parameters (yield and forage quality variables) in 153 permanent grasslands located in the Massif Central of France. Grasslands were sampled at two vegetation stages in the first growth cycle. Botanical composition, yield, ash, crude protein, neutral detergent fibre, acid detergent fibre, acid detergent lignin, organic matter digestibility (OMD) and voluntary intake (VI) were estimated for each sample. Temporal variability in species–forage parameter relationships were accounted for using innovative multivariate analyses applied mainly in ecological science. Crude protein and OMD were weakly correlated when each harvest time was analysed separately. Species–forage parameter relationships remained stable during the first growth cycle. The stability of these relationships indicates that permanent grasslands dominated by competitive species were associated with high yield and forage quality values whereas permanent grasslands composed of conservative species and/or high proportions of senescent material were associated with high structural carbohydrate values and low yield, OMD and VI values. Based on these relationships, we propose a typology of permanent grasslands along with a set of indicator species enabling non‐specialist botanists to easily classify grasslands for grassland management purposes. 相似文献
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110.
N. Martín‐Rodrigues J. Sanchez‐Zabala I. Salcedo J. Majada C. González‐Murua M. K. Duñabeitia 《Plant pathology》2015,64(6):1336-1348
Pine root infection by Fusarium circinatum has been reported in the literature, but the underlying pathogenic interaction is poorly understood. A green fluorescent protein (GFP)‐tagged F. circinatum isolate, together with confocal microscopy, was used in order to monitor the events associated with root infection of Pinus radiata seedlings. It was found that in order to reach and successfully infect pine roots, F. circinatum employed features that are similar to those previously described for other root‐infecting pathogens, such as mycelial strands, single runner hyphae and simple hyphopodia as well as other features that are reminiscent of those that are known to be involved in biotrophic invasion, such as bulbous invasive hyphae and filamentous invasive hyphae. Abundant sporulation was observed at the root surface as well as inside tracheids both in roots and in the root collar region. The fungus can spread from the roots to the aerial parts of the plant, and once there, colonization appears to be similar to the process that occurs when the pathogen is inoculated in the stem. Wilting symptoms and plant demise may be the result of a reduction in water uptake by roots and of the blockage of the vascular system by fungal hyphae and resin. 相似文献