251 research outputs found

    A Joint Model for Unsupervised Chinese Word Segmentation

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    In this paper, we propose a joint model for unsupervised Chinese word segmentation (CWS). Inspired by the 'products of experts' idea, our joint model firstly combines two generative models, which are word-based hierarchical Dirichlet process model and character-based hidden Markov model, by simply multiplying their probabilities together. Gibbs sampling is used for model inference. In order to further combine the strength of goodness-based model, we then integrated nVBE into our joint model by using it to initializing the Gibbs sampler. We conduct our experiments on PKU and MSRA datasets provided by the second SIGHAN bakeoff. Test results on these two datasets show that the joint model achieves much better results than all of its component models. Statistical significance tests also show that it is significantly better than stateof- The-art systems, achieving the highest F-scores. Finally, analysis indicates that compared with nVBE and HDP, the joint model has a stronger ability to solve both combinational and overlapping ambiguities in Chinese word segmentation.,. ? 2014 Association for Computational Linguistics.EI

    Transparent glass ceramic containing NdF3 nanocrystals for magneto-optical application

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    Mechanics of Tunable Helices and Geometric Frustration in Biomimetic Seashells

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    Helical structures are ubiquitous in nature and engineering, ranging from DNA molecules to plant tendrils, from sea snail shells to nanoribbons. While the helical shapes in natural and engineered systems often exhibit nearly uniform radius and pitch, helical shell structures with changing radius and pitch, such as seashells and some plant tendrils, adds to the variety of this family of aesthetic beauty. Here we develop a comprehensive theoretical framework for tunable helical morphologies, and report the first biomimetic seashell-like structure resulting from mechanics of geometric frustration. In previous studies, the total potential energy is everywhere minimized when the system achieves equilibrium. In this work, however, the local energy minimization cannot be realized because of the geometric incompatibility, and hence the whole system deforms into a shape with a global energy minimum whereby the energy in each segment may not necessarily be locally optimized. This novel approach can be applied to develop materials and devices of tunable geometries with a range of applications in nano/biotechnology

    Efficient Spatial Dataset Search over Multiple Data Sources

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    In this paper, we investigate a novel spatial dataset search paradigm over multiple spatial data sources, which enables users to conduct join and union searches seamlessly. Specifically, we define two search problems called Maximum Intersection Query (MIQ) and Maximum Coverage Query with a Connection constraint (MCQC). To address these problems, we propose a unified Multi-source Spatial Dataset Search (MSDS) framework. In MSDS, we design a multi-layer index to accelerate the MIQ and MCQC. In addition, we prove that the MCQC is NP-hard and design two greedy algorithms to solve the problem. To deal with the constant update of spatial datasets in each data source, we design a dynamic index updating strategy and optimize search algorithms to reduce communication costs and improve search efficiency. We evaluate the efficiency of MSDS on five real-world data sources, and the experimental results show that our framework is able to achieve a significant reduction in running time and communication cost

    MODULATING MULTIPLE DRUG RESISTANCE VIA CO-DELIVERY OF NANOPARTICLE

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    When various mechanisms in cancer causing cells show resistance towards one or many chemotherapeutics, it hinders the efficacy of chemotherapy. This is referred as multidrug resistance. There are several factors that contribute in MDR. This research specifically focuses on modulate resistance towards multiple drugs by co-delivery of the nanoparticle. This research review has highlighted several delivery systems of nanodrug for overcoming the mechanism followed by MDR. This is done by exploiting, evading or neutralizing the pumps of drug efflux. The research essay has specifically discussed five different system categories. These categories are Mdr-1 and survivin-targeting, Docetaxel and siRNA, Paclitaxel and curcumin, Doxorubicin and paclitaxel and Doxorubicin and PSC 833. Based on the overall discussion, a brief summary is provided. Keywords: Drug resistance, nanomedicine, co-delivery, drug delivery

    Human impacts on the cladoceran community of Jili Lake, arid NW China, over the past century

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    Deterioration of aquatic ecosystems, as a consequence of human-induced disturbances, is a critical global concern. To fully understand the responses of aquatic systems to anthropogenic impacts, it is crucial to assess long-term changes in lakes. The water quality of Jili Lake, a large water body in northwest China, has deteriorated recently, owing to the growing impacts of regional warming and human activities. Thus, Jili Lake was a prime candidate for evaluation of historical multi-stressor impacts. Meteorological data, historical documents, and assemblages of cladoceran microfossils in the sediments of Jili Lake were employed to investigate changes in the cladoceran community over the past century, and to evaluate the response of that aquatic community to human activities. From the 1920s to the 1950s, species richness of the cladoceran community was high, which reflected conditions of relatively low human impact. From the 1960s to 1970s, a sharp decrease in Bosmina longirostris, a planktonic cladoceran species, suggested a decrease in water level as a result of dam construction and intensified water exploitation. Since the 1980s, the water level in the lake has been restored, but increased fish farming and construction of a water storage facility caused salinisation and eutrophication of Jili Lake. Accordingly, the cladoceran community displayed distinct signs of a regime shift, with a gradual transition to dominance of B. longirostris and a sharp decrease in littoral species (e.g. Leydigia leydigi, L. acanthocercoides, Alona quadrangularis, Alona affinis). Our results suggest that human-induced disturbances were the main factor that drove changes in the cladoceran community since about the mid-20th century.Peer reviewe
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