4,872 research outputs found

    On-chip differential interference contrast microscopy using lensless digital holography.

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    We introduce the use of a birefringent crystal with lensless digital holography to create an on-chip differential interference contrast (DIC) microscope. Using an incoherent source with a large aperture, in-line holograms of micro-objects are created, which interact with a uniaxial crystal and an absorbing polarizer, encoding differential interference contrast information of the objects on the chip. Despite the fact that a unit fringe magnification and an incoherent source with a large aperture have been used, holographic digital processing of such holograms rapidly recovers the differential phase contrast image of the specimen over a large field-of-view of approximately 24 mm(2)

    Analytical investigation of marine casualties at the Strait of Istanbul with SWOT-AHP method

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    The Strait of Istanbul is one of the most dangerous and busiest sea passages, according to its narrowness, sharp turns, currents, heavy traffic and many other important factors. Despite the latest precautions, marine incidents still occur, especially in narrow seaways. This study shows that a management tool that is specifically applied for reducing marine casualties and consequently enhancement of safety and ship management performance can be used to prevent accidents and casualties in maritime transportation. In this study, factors which affect marine casualties examined and determined with SWOT (strengths, weaknesses, opportunities and threats) analysis method and weighting of the factors determined by using the AHP (analytic hierarchy process) method. With this approach, strategic action plans were developed for minimizing shipping casualties at the Strait of Istanbul, taking into account the weighting factors and previously happened accidents

    Static index pruning in web search engines: Combining term and document popularities with query views

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    Cataloged from PDF version of article.Static index pruning techniques permanently remove a presumably redundant part of an inverted file, to reduce the file size and query processing time. These techniques differ in deciding which parts of an index can be removed safely; that is, without changing the top-ranked query results. As defined in the literature, the query view of a document is the set of query terms that access to this particular document, that is, retrieves this document among its top results. In this paper, we first propose using query views to improve the quality of the top results compared against the original results. We incorporate query views in a number of static pruning strategies, namely term-centric, document-centric, term popularity based and document access popularity based approaches, and show that the new strategies considerably outperform their counterparts especially for the higher levels of pruning and for both disjunctive and conjunctive query processing. Additionally, we combine the notions of term and document access popularity to form new pruning strategies, and further extend these strategies with the query views. The new strategies improve the result quality especially for the conjunctive query processing, which is the default and most common search mode of a search engine

    Second chance: A hybrid approach for dynamic result caching and prefetching in search engines

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    Cataloged from PDF version of article.Web search engines are known to cache the results of previously issued queries. The stored results typically contain the document summaries and some data that is used to construct the final search result page returned to the user. An alternative strategy is to store in the cache only the result document IDs, which take much less space, allowing results of more queries to be cached. These two strategies lead to an interesting trade-off between the hit rate and the average query response latency. In this work, in order to exploit this trade-off, we propose a hybrid result caching strategy where a dynamic result cache is split into two sections: an HTML cache and a docID cache. Moreover, using a realistic cost model, we evaluate the performance of different result prefetching strategies for the proposed hybrid cache and the baseline HTML-only cache. Finally, we propose a machine learning approach to predict singleton queries, which occur only once in the query stream. We show that when the proposed hybrid result caching strategy is coupled with the singleton query predictor, the hit rate is further improved. © 2013 ACM

    The validity of eight neoclassical facial canons in the Turkish adults

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    The neoclassical canons were used to define the proportions between various areas of the head and face. Therefore, this study was done to establish the neoclassical canons of facial proportions in Turkish adults. A total of 200 healthy adults 20 to 35 years of age were examined. Using anthropometric landmarks, 5 horizontal and 9 vertical direct measurements were made on the faces with a sliding calliper. Results have been compared with 8 neoclassical facial canons. When comparing between sexes, a significant difference has been found in all measurements except the upper facial width, left eye-fissure width, forehead height I and II (p < 0.005). The nasofacial proportion has been found to include the most proportional subjects (33%) followed by the orbito-nasal (30%), the orbital proportion (25%) and the naso-oral proportion (17%) in the female. Considering the male, the orbital proportion has been found to include the most proportional subjects (23%) followed by the orbito-nasal proportion (21%), naso-facial proportion (19%) and the naso-oral proportion (17%). The neoclassical canons have been shown to rarely be applicable to Turkish adults and our results may contribute to determine the concepts of transcultural facial structures
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