46,697 research outputs found
Acinetobacter johnsonii: an Emerging Pathogen for Cultured Blunt Snout Bream Megalobrama amblycephala
Bacteriosis has caused significant economic losses in farmed blunt snout bream Megalobrama amblycephala. Only scarce information is available on Acinetobacter johnsonii as a possible causal agent in M. amblycephala. In this study, a virulent strain temporarily named BY3, was isolated from diseased bream, identified phenotypically and molecularly as A. johnsonii. Phylogenetic trees of 16S rRNA and gyrB gene sequences were constructed to examine the taxonomic position of isolate BY3 and compare it to other known isolates. When screened against a range of common veterinary antibiotics, isolate BY3 has not shown resistance to florfenicol, neomycin, and sulfisoxazole antibiotics in aquaculture. To the best of our knowledge, this is the first report of A. johnsonii infection in farmed blunt snout bream
Shubnikov-de Haas oscillations of a single layer graphene under dc current bias
Shubnikov-de Haas (SdH) oscillations under a dc current bias are
experimentally studied on a Hall bar sample of single layer graphene. In dc
resistance, the bias current shows the common damping effect on the SdH
oscillations and the effect can be well accounted for by an elevated electron
temperature that is found to be linearly dependent on the current bias. In
differential resistance, a novel phase inversion of the SdH oscillations has
been observed with increasing dc bias, namely we observe the oscillation maxima
develop into minima and vice versa. Moreover, it is found that the onset
biasing current, at which a SdH extremum is about to invert, is linearly
dependent on the magnetic field of the SdH extrema. These observations are
quantitatively explained with the help of a general SdH formula.Comment: 5 pages, 4 figures, A few references adde
Finance and Growth for Microenterprises:Evidence from Rural China
Abstract: Using a survey dataset of Chinese rural households, we find that access to external finance is positively associated with the decision to become entrepreneur, the initial investment for microenterprises and the use of external finance. Also, we find that the use of informal finance is positively associated with sales growth of microenterprises with employees, but not of self-employed. We do not find any significant relationship between the use of formal finance and firm growth. Our findings underline the importance of finance for entrepreneurship and microenterprise growth, and the role of informal finance in the absence of efficient formal financial institutions. Key Words: Finance, Entrepreneurship, Growth, China.
Damage evolution and rupture time prediction in thermal barrier coatings subjected to cyclic heating and cooling: an acoustic emission method
The real-time testing and quantitative assessment of damage evolution in thermal barrier coatings (TBCs) is desirable, but still intractable, especially at elevated temperature. In this paper, the fracture process of TBCs subjected to cyclic heating and cooling is monitored using an acoustic emission method. Based on the wavelet analysis of acoustic emission signals, damage modes in TBCs are discriminated. The results show that, due to thermal stress, it is preferential for vertical cracks in the heating stage and interface cracks in the cooling stage. The surface crack density and interface crack length are calculated to obtain the quantitative correlation of damage evolution in TBCs and acoustic emission parameters. The rupture time of TBCs can be predicted by the statistical analysis of acoustic emission signals
Scalable Text and Link Analysis with Mixed-Topic Link Models
Many data sets contain rich information about objects, as well as pairwise
relations between them. For instance, in networks of websites, scientific
papers, and other documents, each node has content consisting of a collection
of words, as well as hyperlinks or citations to other nodes. In order to
perform inference on such data sets, and make predictions and recommendations,
it is useful to have models that are able to capture the processes which
generate the text at each node and the links between them. In this paper, we
combine classic ideas in topic modeling with a variant of the mixed-membership
block model recently developed in the statistical physics community. The
resulting model has the advantage that its parameters, including the mixture of
topics of each document and the resulting overlapping communities, can be
inferred with a simple and scalable expectation-maximization algorithm. We test
our model on three data sets, performing unsupervised topic classification and
link prediction. For both tasks, our model outperforms several existing
state-of-the-art methods, achieving higher accuracy with significantly less
computation, analyzing a data set with 1.3 million words and 44 thousand links
in a few minutes.Comment: 11 pages, 4 figure
Spatial imaging of Zn and other elements in Huanglongbing-affected grapefruit by synchrotron-based micro X-ray fluorescence investigation
Huanglongbing (HLB) is a highly destructive, fast-spreading disease of citrus, causing substantial economic losses to the citrus industry worldwide. Nutrient levels and their cellular distribution patterns in stems and leaves of grapefruit were analysed after graft-inoculation with lemon scions containing 'Candidatus Liberibacter asiaticus' (Las), the heat-tolerant Asian type of the HLB bacterium. After 12 months, affected plants showed typical HLB symptoms and significantly reduced Zn concentrations in leaves. Micro-XRF imaging of Zn and other nutrients showed that preferential localization of Zn to phloem tissues was observed in the stems and leaves collected from healthy grapefruit plants, but was absent from HLB-affected samples. Quantitative analysis by using standard references revealed that Zn concentration in the phloem of veins in healthy leaves was more than 10 times higher than that in HLB-affected leaves. No significant variation was observed in the distribution patterns of other elements such as Ca in stems and leaves of grapefruit plants with or without graft-inoculation of infected lemon scions. These results suggest that reduced phloem transport of Zn is an important factor contributing to HLB-induced Zn deficiency in grapefruit. Our report provides the first in situ, cellular level visualization of elemental variations within the tissues of HLB-affected citrus. © 2014 © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology
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