1,476 research outputs found

    Feature learning for information-extreme classifier

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    The feature learning algorithm for information-extreme classifier by clustering of Fast Retina Keypoint binary descriptor, calculated for local features, and usage of spatial pyramid kernel for increasing noise immunity and informativeness of feature representation are considered. Proposed a method of parameters optimization for feature extractor and decision rules based on multi-level coarse features coding using information criterion and population-based search algorithm

    Data_Sheet_1_Karst tiankeng create a unique habitat for the survival of soil microbes: Evidence from ecoenzymatic stoichiometry.docx

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    Clarifying the soil microbial metabolism and resource limitations could help to understand the functions and processes of aboveground ecosystems, as well as to predict ecosystem stability under global climate change. Karst tiankeng is a kind of large-scale negative surface terrain on the surface which is similar to an oasis in degraded karst landscapes, but their soil microbial resource limitations still unclear. In this study, we evaluated and compared the soil microbial resource limitation in non-degraded tiankeng (NDT), moderately degraded tiankeng (MDT), heavily degraded tiankeng (HDT), and outside tiankeng (OT) by calculating soil ecoenzymatic stoichiometry. Overall, soil microbial communities were more limited by C and P in karst tiankeng ecosystem. The soil microbial C and P limitations significantly differed with the karst tiankeng degradation increased, and the lowest C and P limitations were observed in NDT. The higher microbial C and P limitations were observed in OT. Linear regression and redundancy analysis indicated that soil microbial C and P limitations were significantly influenced by soil nutrients. Karst tiankeng degradation influence the biogeochemical cycle and function of karst tiankeng systems. Our results highlight that karst tiankeng (especially the NDT) can provide a stable habitat for the survival of microorganisms in karst areas. Karst tiankeng is essential for regional ecological restoration and biodiversity conservation.</p

    Hydrogen Abstraction of Camphor Catalyzed by Cytochrome P450<sub>cam</sub>: A QM/MM Study

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    A combined quantum mechanics and molecular mechanics (QM/MM, QM = UB3LYP-D3, MM = AMBER) method is used to study the hydrogen abstraction reaction in P450<sub>cam</sub> catalyzed hydroxylation of camphor in the quartet state. Compared to QM/MM calculations in the literature, this study uses larger basis sets for the most important atoms at the active site and QM/MM Hessian harmonic frequency calculations to determine the standard Gibbs free energy of activation and kinetic isotope effect. The QM/MM covalent boundary is treated with a capping hydrogen atom method, which is simple and robust. An energy barrier of 21.3 kcal/mol and a standard free energy of activation of 16.8 kcal/mol are obtained for this hydrogen abstraction reaction. These values are similar to those reported in the literature, suggesting that when a general protocol is followed, QM/MM results are reproducible. It is found that using a sufficiently large basis set is important to minimize basis set errors

    Wetting and Interfacial Properties of Water Nanodroplets in Contact with Graphene and Monolayer Boron–Nitride Sheets

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    Born–Oppenheim quantum molecular dynamics (QMD) simulations are performed to investigate wetting, diffusive, and interfacial properties of water nanodroplets in contact with a graphene sheet or a monolayer boron–nitride (BN) sheet. Contact angles of the water nanodroplets on the two sheets are computed for the first time using QMD simulations. Structural and dynamic properties of the water droplets near the graphene or BN sheet are also studied to gain insights into the interfacial interaction between the water droplet and the substrate. QMD simulation results are compared with those from previous classic MD simulations and with the experimental measurements. The QMD simulations show that the graphene sheet yields a contact angle of 87°, while the monolayer BN sheet gives rise to a contact angle of 86°. Hence, like graphene, the monolayer BN sheet is also weakly hydrophobic, even though the BN bonds entail a large local dipole moment. QMD simulations also show that the interfacial water can induce net positive charges on the contacting surface of the graphene and monolayer BN sheets, and such charge induction may affect electronic structure of the contacting graphene in view that graphene is a semimetal. Contact angles of nanodroplets of water in a supercooled state on the graphene are also computed. It is found that under the supercooled condition, water nanodroplets exhibit an appreciably larger contact angle than under the ambient condition

    Comparison of the China and WHO length/height-for-age SD curves for girls.

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    <p>Length for girls 0–3 years and height 3–18 for China, and length 0–2 years and height 2–19 for WHO.</p

    Comparison of the China and WHO weight-for-length SD curves for girls.

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    <p>Comparison of the China and WHO weight-for-length SD curves for girls.</p

    Trends in obesity prevalence in gender and age, 1986–2006.

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    <p>Results shown are representative of the 8 cities surveyed, not including Guangzhou.</p>a<p>pp/y, percentage points/year.</p>b<p>Chi-square test for trend, P<0.01.</p

    Trends in obesity prevalence in cities, 1986–2006.

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    <p>Results shown are representative of the 8 cities surveyed, not including Guangzhou.</p>a<p>pp/y, percentage points/year.</p>b<p>Chi-square test for trend, P<0.01.</p

    Comparison of the China and WHO weight-for-age SD curves for girls.

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    <p>Comparison of the China and WHO weight-for-age SD curves for girls.</p

    Comparison of the China and WHO BMI-for-age SD curves for boys.

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    <p>Length based BMI for boys 0–3 years and height 3–18 for China, and length based BMI 0–2 years and height 2–19 for WHO.</p
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