66,522 research outputs found

    A rapid staining-assisted wood sampling method for PCR-based detection of pine wood nematode Bursaphelenchus xylophilus in Pinus massoniana wood tissue

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    For reasons of unequal distribution of more than one nematode species in wood, and limited availability of wood samples required for the PCR-based method for detecting pinewood nematodes in wood tissue of Pinus massoniana, a rapid staining-assisted wood sampling method aiding PCR-based detection of the pine wood nematode Bursaphelenchus xylophilus (Bx) in small wood samples of P. massoniana was developed in this study. This comprised a series of new techniques: sampling, mass estimations of nematodes using staining techniques, and lowest limit Bx nematode mass determination for PCR detection. The procedure was undertaken on three adjoining 5-mg wood cross-sections, of 0.5 · 0.5 · 0.015 cm dimension, that were cut from a wood sample of 0.5 · 0.5 · 0.5 cm initially, then the larger wood sample was stained by acid fuchsin, from which two 5-mg wood cross-sections (that adjoined the three 5-mg wood cross-sections, mentioned above) were cut. Nematode-staining-spots (NSSs) in each of the two stained sections were counted under a microscope at 100· magnification. If there were eight or more NSSs present, the adjoining three sections were used for PCR assays. The B. xylophilus – specific amplicon of 403 bp (DQ855275) was generated by PCR assay from 100.00% of 5-mg wood cross-sections that contained more than eight Bx NSSs by the PCR assay. The entire sampling procedure took only 10 min indicating that it is suitable for the fast estimation of nematode numbers in the wood of P. massonina as the prelimary sample selections for other more expensive Bx-detection methods such as PCR assay

    Continuous quantum phase transition in a Kondo lattice model

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    We study the magnetic quantum phase transition in an anisotropic Kondo lattice model. The dynamical competition between the RKKY and Kondo interactions is treated using an extended dynamic mean field theory (EDMFT) appropriate for both the antiferromagnetic and paramagnetic phases. A quantum Monte Carlo approach is used, which is able to reach very low temperatures, of the order of 1% of the bare Kondo scale. We find that the finite-temperature magnetic transition, which occurs for sufficiently large RKKY interactions, is first order. The extrapolated zero-temperature magnetic transition, on the other hand, is continuous and locally critical.Comment: 4 pages, 4 figures; updated, to appear in PR

    Do ESOPs enhance firm performance? Evidence from China's reform experiment

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    China introduced employee stock ownership plans (ESOPs) in 1992 purely as an employee incentive scheme. The government initiated the policy experiment on ESOPs as part of China's reform of its state-owned enterprises, and it was abruptly terminated 2. years after initiation. This policy experiment resulted in an exogenous sample of ESOPs that allows us to provide the first evidence from Chinese firms on the performance-ESOP relation. After examining a variety of performance measures, including ROA, ROE, Tobin's q, and productivity, we find little difference in performance between ESOP firms and non-ESOP firms. © 2010 Elsevier B.V.postprin

    A hand shape recognizer from simple sketches

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    Hand shape recognition is one of the most important techniques used in human-computer interaction. However, it often takes developers great efforts to customize their hand shape recognizers. In this paper, we present a novel method that enables a hand shape recognizer to be built automatically from simple sketches, such as a 'stick-figure' of a hand shape. We introduce the Hand Boltzmann Machine (HBM), a generative model built upon unsupervised learning, to represent the hand shape space of a binary image, and formulate the user provided sketches as an initial guidance for sampling to generate realistic hand shape samples. Such samples are then used to train a hand shape recognizer. We evaluate our method and compare it with other state-of-the-art models in three aspects, namely i) its capability of handling different sketch input, ii) its classification accuracy, and iii) its ability to handle occlusions. Experimental results demonstrate the great potential of our method in real world applications. © 2013 IEEE.published_or_final_versio

    Critical comments on the paper "Crossing ω=1\omega=-1 by a single scalar field on a Dvali-Gabadadze-Porrati brane" by H Zhang and Z-H Zhu [Phys.Rev.D75,023510(2007)]

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    It is demonstrated that the claim in the paper "Crossing ω=1\omega=-1 by a single scalar field on a Dvali-Gabadadze-Porrati brane" by H Zhang and Z-H Zhu [Phys.Rev.D75,023510(2007)], about a prove that there do not exist scaling solutions in a universe with dust in a Dvali-Gabadadze-Porrati (DGP) braneworld scenario, is incorrect.Comment: 5 pages, 8 eps figure
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