2,038 research outputs found

    Dry season rice varieties for the Ord River Valley

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    PREVIOUS experimental work at the Kimberley Research Station (Langfield 1961) showed that, in general, indica varieties of rice are best adapted for wet-season sowing and japonica varieties for dry-season sowing. This article gives the results of three rice variety and time of planting experiments carried out at Kimberley Research Station in the I960, 1961, and 1962 dry seasons. The recommendation is to sow the variety Caloro during May

    Phosphate requirements of rice in the Ord River Valley

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    A three-year experiment on the initial and maintenance phosphate requirements of wet-season rice was carried out at Kimberley Research Station between 1960 and 1963. Application of 2 cwt. per acre superphosphate as the first application on new land, followed by annual application of 1J cwt. per acre is recommended

    Hyperparameter Importance Across Datasets

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    With the advent of automated machine learning, automated hyperparameter optimization methods are by now routinely used in data mining. However, this progress is not yet matched by equal progress on automatic analyses that yield information beyond performance-optimizing hyperparameter settings. In this work, we aim to answer the following two questions: Given an algorithm, what are generally its most important hyperparameters, and what are typically good values for these? We present methodology and a framework to answer these questions based on meta-learning across many datasets. We apply this methodology using the experimental meta-data available on OpenML to determine the most important hyperparameters of support vector machines, random forests and Adaboost, and to infer priors for all their hyperparameters. The results, obtained fully automatically, provide a quantitative basis to focus efforts in both manual algorithm design and in automated hyperparameter optimization. The conducted experiments confirm that the hyperparameters selected by the proposed method are indeed the most important ones and that the obtained priors also lead to statistically significant improvements in hyperparameter optimization.Comment: \c{opyright} 2018. Copyright is held by the owner/author(s). Publication rights licensed to ACM. This is the author's version of the work. It is posted here for your personal use, not for redistribution. The definitive Version of Record was published in Proceedings of the 24th ACM SIGKDD International Conference on Knowledge Discovery & Data Minin

    QM/MM study of the taxadiene synthase mechanism

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    Combined quantum mechanics/molecular mechanics (QM/MM) calculations were used to investigate the reaction mechanism of taxadiene synthase (TXS). TXS catalyzes the cyclization of geranylgeranyl diphosphate (GGPP) to taxadiene (T) and four minor cyclic products. All these products originate from the deprotonation of carbocation intermediates. The reaction profiles for the conversion of GGPP to T as well as to minor products were calculated for different configurations of relevant TXS carbocation complexes. The QM region was treated at the M06‐2X/TZVP level, while the CHARMM27 force field was used to describe the MM region. The QM/MM calculations suggest a reaction pathway for the conversion of GGPP to T, which slightly differs from previous proposals regarding the number of reaction steps and the conformation of the carbocations. The QM/MM results also indicate that the formation of minor products via water‐assisted deprotonation of the carbocations is highly exothermic, by about −7 to −23 kcal/mol. Curiously, however, the computed barriers and reaction energies indicate that the formation of some of the minor products is more facile than the formation of T. Thus, the present QM/MM calculations provide detailed insights into possible reaction pathways and into the origin of the promiscuity of TXS, but they do not reproduce the product distribution observed experimentally

    Temperature-dependent out-of-plane anisotropy in compressively strained La<sub>0.67</sub>Sr<sub>0.33</sub>MnO<sub>3</sub> thin films

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    We studied the temperature and strain dependence of the perpendicular magnetic anisotropy in La0.67Sr0.33MnO3 thin films by performing temperature- and angle-dependent magnetotransport measurements. Three films of similar thickness (14 u.c., 14 u.c. and 15 u.c.) but with different out-of-plane crystallographic strain (1.9%, 0.9% and -0.7%) are studied. The films are grown on LaAlO3 and SrTiO3 substrates by pulsed laser deposition. We observe a clear increase in the out-of-plane magnetic anisotropy with increasing out-of-plane strain in the angle-dependent magnetotransport measurements which is present up to 80 K for the highest (1.9%) strained sample. The deformation of the unit cell, as discussed in earlier reports, point to the magnetocrystalline anisotropy as the main driver altering the magnetic easy axis direction. Our results highlight the utility of the effective magnetocrystalline anisotropy as a tool to control the desired anisotropy in crystalline thin films of La0.67Sr0.33MnO3

    Practical sand transport formula for non-breaking waves and currents

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    Open Access funded by Engineering and Physical Sciences Research Council Under a Creative Commons license Acknowledgements This work is part of the SANTOSS project (‘SANd Transport in OScillatory flows in the Sheet-flow regime’) funded by the UK's EPSRC (GR/T28089/01) and STW in The Netherlands (TCB.6586). JW acknowledges Deltares strategic research funding under project number 1202359.09. Richard Soulsby is gratefully acknowledged for valuable discussions and feedback on the formula during the SANTOSS project.Peer reviewedPostprin

    Molecular dynamics study of taxadiene synthase catalysis

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    Molecular dynamics (MD) simulations have been performed to study the dynamic behavior of noncovalent enzyme carbocation complexes involved in the cyclization of geranylgeranyl diphosphate to taxadiene catalyzed by taxadiene synthase (TXS). Taxadiene and the observed four side products originate from the deprotonation of carbocation intermediates. The MD simulations of the TXS carbocation complexes provide insights into potential deprotonation mechanisms of such carbocations. The MD results do not support a previous hypothesis that carbocation tumbling is a key factor in the deprotonation of the carbocations by pyrophosphate. Instead water bridges are identified which may allow the formation of side products via multiple proton transfer reactions. A novel reaction path for taxadiene formation is proposed on the basis of the simulations
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