Critical evaluation of methods for determining total organic phosphorus in tropical soils

The determination of total organic phosphorus (TOP) in soils presents several methodological problems, particularly on strongly weathered and tropical soils. We reviewed the application of several methods for TOP determination to soils from different zones of the globe and evaluated the applicability of one ignition and two extraction methods to tropical soils from Brazil and Ghana. Reproducibility (coefficients of variation) was within 6% for the ignition method, and 13% for the extraction methods, due to the simplicity of the former. The two extraction methods produced results similar to each other, while the ignition method generally gave higher TOP contents. Unusually low C to organic P ratios indicate that the ignition method overestimated TOP in several soils. The Bowman extraction method, developed on weakly weathered soils, appeared also suitable for a variety of tropical soils

A simple inverse method for the interpretation of pumped flowing fluid electrical conductivity logs

Pumped flowing fluid electrical conductivity (FFEC) logs, also known as pumped borehole dilution testing, is an experimentally easy‐to‐perform approach to evaluating vertical variations in the hydraulic conductivity of an aquifer. In contrast to the simplicity of the logging equipment, analysis of the data is complex and laborious. Current methods typically require repeated solution of the advection‐dispersion equation (ADE) for describing the flow in the borehole and comparison with the experimental results. In this paper, we describe a direct solution for determining borehole fluid velocity that bypasses the need for complex numerical computation and repetitive optimization. The method rests on the observation that, while solving the ADE for concentration profile in the borehole (as required for modeling and combined methods) is computationally challenging, the solution for flow distribution along the length of the borehole given concentration data is straightforward. The method can accommodate varying borehole diameters, and uses the fact that multiple profiles are taken in the standard logging approach to reduce the impact of noise. Data from both a simulated borehole and from a field test are successfully analyzed. The method is implemented in a spreadsheet, which is available as supporting information material to this paper

Composition, degradation and utilization of endosperm during germination in the oil palm (Elaeis guineensis Jacq.)

The insoluble carbohydrate and lipid fractions, and α-D-galactosidase, β-D-mannosidase and isocitrate lyase activities were studied in the various tissues of oil palm (Elaeis guineensis Jacq.) kernels prior to and during germination. In ungerminated kernels insoluble carbohydrate and lipid constituted 36 and 47% of endosperm dry weight respectively. During germination the thick endosperm cell walls became markedly thinner, concurrent with a significant decrease in the percentage of insoluble carbohydrate and an increase in α-galactosidase and β-mannosidase activity in both degraded and residual endosperm. The proportion of lipid in degraded endosperm also increased significantly. The insoluble carbohydrate appears to be a galactomannan located in the secondary walls of the endosperm. No galactomannan was detected in oil palm embryos or haustoria. Isocitrate lyase was present in, and confined to, tissues of the haustorium of germinating kernels. The enzyme was not active in endosperm at any stage of germination, nor was it active in embryos before or at the end of imbibition. The results suggest that galactomannan is the second largest component of oil palm endosperm and that it is utilized more rapidly than lipid during the early stages of germination. The fact that isocitrate lyase activity is confined to the haustorium suggests that in Elaeis gluconeogenesis, the conversion of triglyceride to carbohydrate, takes place entirely within the cotyledon of the seed

Active flow control systems architectures for civil transport aircraft

Copyright @ 2010 American Institute of Aeronautics and AstronauticsThis paper considers the effect of choice of actuator technology and associated power systems architecture on the mass cost and power consumption of implementing active flow control systems on civil transport aircraft. The research method is based on the use of a mass model that includes a mass due to systems hardware and a mass due to the system energy usage. An Airbus A320 aircraft wing is used as a case-study application. The mass model parameters are based on first-principle physical analysis of electric and pneumatic power systems combined with empirical data on system hardware from existing equipment suppliers. Flow control methods include direct fluidic, electromechanical-fluidic, and electrofluidic actuator technologies. The mass cost of electrical power distribution is shown to be considerably less than that for pneumatic systems; however, this advantage is reduced by the requirement for relatively heavy electrical power management and conversion systems. A tradeoff exists between system power efficiency and the system hardware mass required to achieve this efficiency. For short-duration operation the flow control solution is driven toward lighter but less power-efficient systems, whereas for long-duration operation there is benefit in considering heavier but more efficient systems. It is estimated that a practical electromechanical-fluidic system for flow separation control may have a mass up to 40% of the slat mass for a leading-edge application and 5% of flap mass for a trailing-edge application.This work is funded by the Sixth European Union Framework Programme as part of the AVERT project (Contract No. AST5-CT-2006-030914

Let the river erode! Enabling lateral migration increases geomorphic unit diversity

River restoration practice frequently employs conservative designs that create and maintain prescribed, static morphology. Such approaches ignore an emerging understanding of resilient river systems that typically adjust their morphology in response to hydrologic, vegetative and sediment supply changes. As such, using increased dynamism as a restoration design objective will arguably yield more diverse and productive habitats, better managed expectations, and more self-sustaining outcomes. Here, we answer the following question: does restoring lateral migration in a channelised river that was once a wandering gravel-bed river, result in more diverse in-channel geomorphology? We acquired pre- and post-restoration topographic surveys on a segment of the Allt Lorgy, Scotland to quantify morphodynamics and systematically map geomorphic units, using Geomorphic Unit Tool (GUT) software. GUT implements topographic definitions to discriminate between a taxonomy of fluvial landforms that have been developed from an extension of the River Styles framework, using 3-tiered hierarchy: (1) differentiation based on stage or elevation relative to channel; (2) classification of form based on shape (mound, bowl, trough, saddle, plane, wall); and (3) mapping geomorphic units based on attributes (e.g., position and orientation). Results showed restoration increased geomorphic unit diversity, with the Shannon Diversity Index increasing from 1.40 pre-restoration (2012) to 2.04 (2014) and 2.05 (2016) after restoration. Channel widening, due to bank erosion, caused aerial coverage of in-channel geomorphic units to increase 23% after restoration and 6% further in the two-years following restoration. Once bank protection was removed, allowing bank erosion yieled a local supply of sediment to enable the formation and maintenance of lateral and point bars, riffles and diagonal bar complexes, and instream wood created structurally-forced pools and riffles. The methodology used systematically quantifies how geomorphic unit diversity increases when a river is given back its freedom space. The framework allows for testing restoration design hypotheses in post-project appraisal

Periscope Proteins are variable-length regulators of bacterial cell surface interactions

Changes at the cell surface enable bacteria to survive in dynamic environments, such as diverse niches of the human host. Here, we reveal “Periscope Proteins” as a widespread mechanism of bacterial surface alteration mediated through protein length variation. Tandem arrays of highly similar folded domains can form an elongated rod-like structure; thus, variation in the number of domains determines how far an N-terminal host ligand binding domain projects from the cell surface. Supported by newly available long-read genome sequencing data, we propose that this class could contain over 50 distinct proteins, including those implicated in host colonization and biofilm formation by human pathogens. In large multidomain proteins, sequence divergence between adjacent domains appears to reduce interdomain misfolding. Periscope Proteins break this “rule,” suggesting that their length variability plays an important role in regulating bacterial interactions with host surfaces, other bacteria, and the immune system

Nitrogen fertilizer and nitrapyrin for greenhouse gas reduction in wolfberry orchards on the Qinghai–Tibetan Plateau

Wolfberry production has become a major agro-industry on the Qinghai–Tibetan Plateau, causing increased nitrogen (N) pollution and greenhouse gas (GHG) emissions. Appropriate N fertilizer rate and nitrification inhibitors may mitigate GHG emissions and improve N use efficiency. A 2-year field experiment was conducted to measure the effects of N application rate and nitrapyrin on GHG emissions, to reduce GHG emissions and N pollution. We used eight treatments: Control (CK), 667 kg·ha‾¹ N (Con), 400 kg·ha‾¹ N (N₄₀₀), 267 kg·ha‾¹ N (N₂₆₇), 133 kg·ha‾¹ N (N₁₃₃), 400 kg·ha‾¹ N plus 2.00 kg·ha‾¹ nitrapyrin (N₄₀₀I₂.₀₀), 267 kg·ha‾¹ N plus 1.33 kg·ha‾¹ nitrapyrin (N₂₆₇I₁.₃₃) and 133 kg·ha‾¹ N plus 0.67 kg·ha‾¹ nitrapyrin (N₁₃₃I₀.₆₇). Compared with Con treatment, N₄₀₀ maintained fruit yield and increased net income, but saved 40% of N fertilizer and decreased the cumulative N₂O emission by 14–16%. Compared to N₄₀₀, N₂₆₇ and N₁₃₃ treatments, the cumulative N₂O emission of N₄₀₀I₂.₀₀, N₂₆₇I₁.₃₃ and N₁₃₃I₀.₆₇ treatments was reduced by 28.5–45.1%, 26.6–29.9% and 33.8–45.9%, respectively. Furthermore, N₄₀₀I₂.₀₀ resulted in the highest wolfberry yield and net income. The emissions of CH₄ and CO₂ were not significantly different among treatments. Moreover, the global warming potential (GWP) and the greenhouse gas emission intensity (GHGI) of N₄₀₀I₂.₀₀ declined by 45.6% and 48.6% compared to Con treatment. Therefore, 400 kg·ha‾¹ N combined with 2.00 kg·ha‾¹ nitrapyrin was shown to be a promising management technique for maintaining wolfberry yield while minimizing GWP and GHGI

Low-energy Pion-nucleon Scattering

This paper contains the results of an analysis of recent low-energy pion-nucleon scattering experiments. Obtained are phase shifts, the pion-nucleon coupling constant and an estimate of the Sigma term.Comment: 30 pages, 11 figures, LaTe