116 research outputs found

    Self Adaptive Artificial Bee Colony for Global Numerical Optimization

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    AbstractThe ABC algorithm has been used in many practical cases and has demonstrated good convergence rate. It produces the new solution according to the stochastic variance process. In this process, the magnitudes of the perturbation are important since it can affect the new solution. In this paper, we propose a self adaptive artificial bee colony, called self adaptive ABC, for the global numerical optimization. A new self adaptive perturbation is introduced in the basic ABC algorithm, in order to improve the convergence rates. 23 benchmark functions are employed in verifying the performance of self adaptive ABC. Experimental results indicate our approach is effective and efficient. Compared with other algorithms, self adaptive ABC performs better than, or at least comparable to the basic ABC algorithm and other state-of-the-art approaches from literature when considering the quality of the solution obtained

    Interference of steroidogenesis by gold nanorod core/silver shell nanostructures: Implications for reproductive toxicity of silver nanomaterials

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    Silver nanomaterials are widely used in personal care products. Recent studies have indicated that these nanomaterials may penetrate the blood-placental barrier and gain access to the ovaries. It is largely unknown how silver nanomaterials influence ovarian physiology and functions such as hormone production. This study examines the in vitro toxicology of silver nanomaterials, focusing especially on cytotoxicity and steroidogenesis while exploring their underlying mechanisms. In this study, primary rat granulosa cells were exposed to gold nanorod core/silver shell nanostructures (Au@Ag NRs), which were compared to cells exposed to gold nanorods only. The Au@Ag NRs generated more reactive oxygen species (ROS), reduced mitochondrial membrane potential, and decreased production of adenosine triphosphate. Au@Ag NRs promoted steroidogenesis, including progesterone and estradiol, in a time and dose-dependent manner. Chemical reactivity and transformation of Au@Ag NRs were then studied by electron spin resonance spectroscopy (ESR) and X-ray absorption near edge structure, which identified the generation of free radicals and intracellular silver species. These results suggested that both particle-specific activity and intracellular silver ion release of Au@Ag Please click Additional Files below to see the full abstract

    Shrub type dominates the vertical distribution of leaf C : N : P stoichiometry across an extensive altitudinal gradient

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    Understanding leaf stoichiometric patterns is crucial for improving predictions of plant responses to environmental changes. Leaf stoichiometry of terrestrial ecosystems has been widely investigated along latitudinal and longitudinal gradients. However, very little is known about the vertical distribution of leaf C :N: P and the relative effects of environmental parameters, especially for shrubs. Here, we analyzed the shrub leaf C, N and P patterns in 125 mountainous sites over an extensive altitudinal gradient (523-4685 m) on the Tibetan Plateau. Results showed that the shrub leaf C and C :N were 7.3-47.5% higher than those of other regional and global flora, whereas the leaf N and N: P were 10.2-75.8% lower. Leaf C increased with rising altitude and decreasing temperature, supporting the physiological acclimation mechanism that high leaf C (e.g., alpine or evergreen shrub) could balance the cell osmotic pressure and resist freezing. The largest leaf N and high leaf P occurred in valley region (altitude 1500 m), likely due to the large nutrient leaching from higher elevations, faster litter decomposition and nutrient resorption ability of deciduous broadleaf shrub. Leaf N: P ratio further indicated increasing N limitation at higher altitudes. Interestingly, drought severity was the only climatic factor positively correlated with leaf N and P, which was more appropriate for evaluating the impact of water status than precipitation. Among the shrub ecosystem and functional types (alpine, subalpine, montane, valley, evergreen, deciduous, broadleaf, and conifer), their leaf element contents and responses to environments were remarkably different. Shrub type was the largest contributor to the total variations in leaf stoichiometry, while climate indirectly affected the leaf C :N: P via its interactive effects on shrub type or soil. Collectively, the large heterogeneity in shrub type was the most important factor explaining the overall leaf C :N: P variations, despite the broad climate gradient on the plateau. Temperature and drought induced shifts in shrub type distribution will influence the nutrient accumulation in mountainous shrubs. © Author(s) 2018

    Towards Semantic e-Science for Traditional Chinese Medicine

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    <p>Abstract</p> <p>Background</p> <p>Recent advances in Web and information technologies with the increasing decentralization of organizational structures have resulted in massive amounts of information resources and domain-specific services in Traditional Chinese Medicine. The massive volume and diversity of information and services available have made it difficult to achieve seamless and interoperable e-Science for knowledge-intensive disciplines like TCM. Therefore, information integration and service coordination are two major challenges in e-Science for TCM. We still lack sophisticated approaches to integrate scientific data and services for TCM e-Science.</p> <p>Results</p> <p>We present a comprehensive approach to build dynamic and extendable e-Science applications for knowledge-intensive disciplines like TCM based on semantic and knowledge-based techniques. The semantic e-Science infrastructure for TCM supports large-scale database integration and service coordination in a virtual organization. We use domain ontologies to integrate TCM database resources and services in a semantic cyberspace and deliver a semantically superior experience including browsing, searching, querying and knowledge discovering to users. We have developed a collection of semantic-based toolkits to facilitate TCM scientists and researchers in information sharing and collaborative research.</p> <p>Conclusion</p> <p>Semantic and knowledge-based techniques are suitable to knowledge-intensive disciplines like TCM. It's possible to build on-demand e-Science system for TCM based on existing semantic and knowledge-based techniques. The presented approach in the paper integrates heterogeneous distributed TCM databases and services, and provides scientists with semantically superior experience to support collaborative research in TCM discipline.</p

    High extinction ratio D-shaped fiber polarizers coated by a double graphene/PMMA stack

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    We demonstrate theoretically and experimentally a high extinction ratio and compact size TE-pass polarizer made by a D-shaped fiber coated with a double graphene/PMMA stack. The light propagating in the core of the fiber can be efficiently coupled into the graphene sheet thanks to the giant enhancement of the modal evanescent field associated with the high refractive index graphene/PMMA cladding. The strong interaction between the light and graphene produces a large attenuation difference between modes with orthogonal polarizations, resulting in an improved extinction ratio and a reduced insertion loss due to the device compactness. A double graphene/PMMA stack coated polarizer with an extinction ratio of up to 36 dB and an insertion loss of 5 dB has been achieved when the device length is only 2.5 mm. The double graphene/PMMA stack has proved to be significantly better than single graphene/PMMA stack and bilayer graphene/PMMA structures, providing a polarizer with maximum extinction ratio of 44 dB for a length of 4 mm. The achieved results indicate that the proposed high extinction ratio polarizer is a promising candidate for novel in-fiber graphene-based devices

    Analysis of Large Phenotypic Variability of EEC and SHFM4 Syndromes Caused by K193E Mutation of the TP63 Gene

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    EEC (ectrodactyly, ectodermal dysplasia, clefting; OMIM 604292) is an autosomal dominant developmental disorder resulting mainly from pathogenic mutations of the DNA-binding domain (DBD) of the TP63 gene. In this study, we showed that K193E mutation in nine affected individuals of a four-generation kindred with a large degree of phenotypic variability causes four different syndromes or TP63-related disorders: EEC, Ectrodactyly-ectodermal dysplasia (EE), isolated ectodermal dysplasia, and isolated Split Hand/Foot Malformation type 4 (SHFM4). Genotype-phenotype and DBD structural modeling analysis showed that the K193-located loop L2-A is associated with R280 through hydrogen bonding interactions, while R280 mutations also often cause large phenotypic variability of EEC and SHFM4. Thus, we speculate that K193 and several other DBD mutation-associated syndromes may share similar pathogenic mechanisms, particularly in the case of the same mutation with different phenotypes. Our study and others also suggest that the phenotypic variability of EEC is attributed, at least partially, to genetic and/or epigenetic modifiers

    Characteristics of ammonium and nitrate fluxes along the roots of Picea asperata

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    Nitrogen (N), ammonium (NH4+) and nitrate (NO3-), is one of the key determinants for plant growth. The interaction of both ions displays a significant effect on their uptake in some species. In the current study, net fluxes of NH4+ and NO3- along the roots of Picea asperata were determined using a Non-invasive Micro-test Technology (NMT). Besides, we examined the interaction of NH4+ and NO3- on the fluxes of both ions, and the plasma membrane (PM) H+-ATPases and nitrate reductase (NR) were taken into account as well. The results demonstrated that the maximal net NH4+ and NO3- influxes were detected at 13-15 mm and 8-10.5 mm from the root apex, respectively. Net NH4+ influx was significantly stimulated with the presence of NO3-, whereas NH4+ exhibited a markedly negative effect on NO3- uptake in the roots of P. asperata. Also, our results indicated that PM H+-ATPases and NR play a key role in the control of N uptake

    Root physiological responses can explain the effects of short-term plant-plant interactions on growth of two subalpine coniferous species

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    Root functional traits play an important role in nutrient acquisition of plants, affecting the outcome of plant-plant interactions. However, few studies have comprehensively investigated the plastic responses of plant root traits to plant-plant interactions. A pot experiment was conducted to quantify the effects of intraspecific and interspecific interactions on seedlings growth and multiple root traits of two coniferous species, Picea asperata and Abies faxoniana. The results showed that plant-plant interactions changed root physiology of two species but did not affect their root system, morphological, architectural and biotic traits. Intraspecific interaction resulted in lower root N content and stronger resource competition than under interspecific interaction. Under intraspecific interaction, P. asperata had lower root vigor and nitrate reductase activity, which impeded the acquisition and utilization of the limited resources, and thus resulted in marginally decreased total biomass; while total biomass for A. faxoniana was not significantly affected. Under interspecific interaction, the high total biomass of A. faxoniana could be explained by rhizosphere interactive effects and reduced metabolic (carbon and nitrogen) costs due to lower root exudative outputs. Our results demonstrate that root physiological responses can explain the effects of short-term plant-plant interactions on plant growth.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
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