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1.
A parallel constrained coding scheme is considered where p-blocks of raw data are encoded simultaneously into q tracks such that the contents of each track belong to a given constraint S. It is shown that as q increases, there are parallel block-decodable encoders for S whose coding ratio p/q converges to the capacity of S. Examples are provided where parallel coding allows block-decodable encoders, while conventional coding, at the same rate, does not. Parallel encoders are then applied as building blocks in the construction of block-decodable encoders for certain families of two-dimensional constraints  相似文献   
2.
A 2-year field experiment was carried out in a sandy soil (Xeropsament-Torripsament) at Nir Yizhaq, Israel, where commercially grown peanut plants were sprayed with different NPKS solutions during the pod-filling period. All foliar sprays were applied in addition to the fertilizer which had been added to the soil before planting. The differences in yield between the treatments were not significant in either year. In the first year, there was a tendency toward increased yields of pods (up to 13%) and of hay (up to 16%) when four foliar fertilizer applications (10 kg N, 1 kg P, 3 kg K and 0.5 kg S/ha/application) were given, at one-week intervals. N was added mainly as urea, P and K as potassium polyphosphate, and S as ammonium sulphate. In the second year, the highest yield was obtained in the control plots and the differences between the treatments were not significant. Utilization of foliar nutrient application seems to be dependent upon availability of these nutrients in the soil.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 1976-E. 1087 series.  相似文献   
3.
The Semantic Web envisions a World Wide Web in which data is described with rich semantics and applications can pose complex queries. To this point, researchers have defined new languages for specifying meanings for concepts and developed techniques for reasoning about them, using RDF as the data model. To flourish, the Semantic Web needs to provide interoperability—both between sites with different terminologies and with existing data and the applications operating on them. To achieve this, we are faced with two problems. First, most of the world’s data is available not in RDF but in XML; XML and the applications consuming it rely not only on the domain structure of the data, but also on its document structure. Hence, to provide interoperability between such sources, we must map between both their domain structures and their document structures. Second, data management practitioners often prefer to exchange data through local point-to-point data translations, rather than mapping to common mediated schemas or ontologies.This paper describes the Piazza system, which addresses these challenges. Piazza offers a language for mediating between data sources on the Semantic Web, and it maps both the domain structure and document structure. Piazza also enables interoperation of XML data with RDF data that is accompanied by rich OWL ontologies. Mappings in Piazza are provided at a local scale between small sets of nodes, and our query answering algorithm is able to chain sets mappings together to obtain relevant data from across the Piazza network. We also describe an implemented scenario in Piazza and the lessons we learned from it.  相似文献   
4.
Learning to Match the Schemas of Data Sources: A Multistrategy Approach   总被引:5,自引:0,他引:5  
Doan  AnHai  Domingos  Pedro  Halevy  Alon 《Machine Learning》2003,50(3):279-301
The problem of integrating data from multiple data sources—either on the Internet or within enterprises—has received much attention in the database and AI communities. The focus has been on building data integration systems that provide a uniform query interface to the sources. A key bottleneck in building such systems has been the laborious manual construction of semantic mappings between the query interface and the source schemas. Examples of mappings are element location maps to address and price maps to listed-price. We propose a multistrategy learning approach to automatically find such mappings. The approach applies multiple learner modules, where each module exploits a different type of information either in the schemas of the sources or in their data, then combines the predictions of the modules using a meta-learner. Learner modules employ a variety of techniques, ranging from Naive Bayes and nearest-neighbor classification to entity recognition and information retrieval. We describe the LSD system, which employs this approach to find semantic mappings. To further improve matching accuracy, LSD exploits domain integrity constraints, user feedback, and nested structures in XML data. We test LSD experimentally on several real-world domains. The experiments validate the utility of multistrategy learning for data integration and show that LSD proposes semantic mappings with a high degree of accuracy.  相似文献   
5.
Five studies examined the effects of chronic and contextual activation of attachment security on reactions to others' needs. The sense of attachment security was contextually primed by asking participants to recollect personal memories, read a story, or look at a picture of supportive others or by subliminally exposing them to proximity-related words. This condition was compared against the priming of neutral themes, positive affect, or attachment-insecurity schemas. Then reports of empathy and personal distress or the accessibility of empathy and personal-distress memories were assessed. Attachment-security priming strengthened empathic reactions and inhibited personal distress. Self-reports of attachment anxiety and avoidance were inversely related to empathy, and attachment anxiety was positively related to personal distress. The discussion emphasizes the relevance of attachment theory for explaining reactions to others' needs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
7.
We derive lower bounds on the capacity of certain two-dimensional (2-D) constraints by considering bounds on the entropy of measures induced by bit-stuffing encoders. A more detailed analysis of a previously proposed bit-stuffing encoder for (d,/spl infin/)-runlength-limited (RLL) constraints on the square lattice yields improved lower bounds on the capacity for all d /spl ges/ 2. This encoding approach is extended to (d,/spl infin/)-RLL constraints on the hexagonal lattice, and a similar analysis yields lower bounds on the capacity for d /spl ges/ 2. For the hexagonal (1,/spl infin/)-RLL constraint, the exact coding ratio of the bit-stuffing encoder is calculated and is shown to be within 0.5% of the (known) capacity. Finally, a lower bound is presented on the coding ratio of a bit-stuffing encoder for the constraint on the square lattice where each bit is equal to at least one of its four closest neighbors, thereby providing a lower bound on the capacity of this constraint.  相似文献   
8.
9.
Digital library information-technology infrastructures   总被引:2,自引:1,他引:1  
This paper charts a research agenda on systems-oriented issues in digital libraries. It focuses on the most central and generic system issues, including system architecture, user-level functionality, and the overall operational environment. With respect to user-level functionality, in particular, it abstracts the overall information lifecycle in digital libraries to five major stages and identifies key research problems that require solution in each stage. Finally, it recommends an explicit set of activities that would help achieve the research goals outlined and identifies several dimensions along which progress of the digital library field can be evaluated.  相似文献   
10.
Low-energy laser (He-Ne) irradiation was found to promote skeletal muscle regeneration in vivo. In this study, its effect on the proliferation and differentiation of satellite cells in vitro was evaluated. Primary rat satellite cells were irradiated for various time periods immediately after preparation, and thymidine incorporation was determined after 2 days in culture. Laser irradiation affected thymidine incorporation in a bell-shaped manner, with a peak at 3 s of irradiation. Three seconds of irradiation caused an induction of cell-cycle regulatory proteins: cyclin D1, cyclin E and cyclin A in an established line of mouse satellite cells, pmi28, and proliferating cell nuclear antigen (PCNA) in primary rat satellite cells. The induction of cyclins by laser irradiation was compatible with their induction by serum refeeding of the cells. Laser irradiation effect on cell proliferation was dependent on the rat's age. At 3 weeks of age, thymidine incorporation in the irradiated cells was more than twofold higher than that in the controls, while at 6 weeks of age this difference had almost disappeared. Myosin heavy chain (MHC) protein levels were twofold lower in the irradiated than in the control cells, whereas the proliferation of the irradiated cells was twofold higher. Fusion percentage was lower in the irradiated compared to non-irradiated cells. In light of these data, the promoting effect of laser irradiation on skeletal muscle regeneration in vivo may be due to its effect on the activation of early cell-cycle regulatory genes in satellite cells, leading to increased proliferation and to a delay in cell differentiation.  相似文献   
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