251 research outputs found
A Joint Model for Unsupervised Chinese Word Segmentation
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
Mechanics of Tunable Helices and Geometric Frustration in Biomimetic Seashells
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
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
Effect of Thickness of Anode Functional Layer on Electrochemical Performance of Ni-Ce0.8Gd0.2O1.9 Anode-Supported Solid Oxide Fuel Cells
MODULATING MULTIPLE DRUG RESISTANCE VIA CO-DELIVERY OF NANOPARTICLE
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
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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