1,411 research outputs found

    BDGS: A Scalable Big Data Generator Suite in Big Data Benchmarking

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    Data generation is a key issue in big data benchmarking that aims to generate application-specific data sets to meet the 4V requirements of big data. Specifically, big data generators need to generate scalable data (Volume) of different types (Variety) under controllable generation rates (Velocity) while keeping the important characteristics of raw data (Veracity). This gives rise to various new challenges about how we design generators efficiently and successfully. To date, most existing techniques can only generate limited types of data and support specific big data systems such as Hadoop. Hence we develop a tool, called Big Data Generator Suite (BDGS), to efficiently generate scalable big data while employing data models derived from real data to preserve data veracity. The effectiveness of BDGS is demonstrated by developing six data generators covering three representative data types (structured, semi-structured and unstructured) and three data sources (text, graph, and table data)

    Iterative disaggregation for a class of lumpable discrete-time stochastic automata networks

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    Cataloged from PDF version of article.Stochastic automata networks (SANs) have been developed and used in the last 15 years as a modeling formalism for large systems that can be decomposed into loosely connected components. In this work, we concentrate on the not so much emphasized discrete-time SANs. First, we remodel and extend an SAN that arises in wireless communications. Second, for an SAN with functional transitions, we derive conditions for a special case of ordinary lumpability in which aggregation is done automaton by automaton. Finally, for this class of lumpable discrete-time SANs we devise an efficient aggregation–iterative disaggregation algorithm and demonstrate its performance on the SAN model of interest. © 2002 Elsevier Science B.V. All rights reserved

    Lumpable continuous-time stochastic automata networks

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    Cataloged from PDF version of article.The generator matrix of a continuous-time stochastic automata network (SAN) is a sum of tensor products of smaller matrices, which may have entries that are functions of the global state space. This paper specifies easy to check conditions for a class of ordinarily lumpable partitionings of the generator of a continuous-time SAN in which aggregation is performed automaton by automaton. When there exists a lumpable partitioning induced by the tensor representation of the generator, it is shown that an efficient aggregation-iterative disaggregation algorithm may be employed to compute the steady-state distribution. The results of experiments with two SAN models show that the proposed algorithm performs better than the highly competitive block Gauss-Seidel in terms of both the number of iterations and the time to converge to the solution. © 2002 Elsevier Science B.V. All rights reserved

    Controlled atmosphere bench-scale calorimetry revisited

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    International audienceThe standard Cone Calorimeter has been designed with an "open configuration", allowing for testing of specimens through use of freely driven room air for combustion. For testing specimens in oxygen depleted atmospheres or in fuel rich combustion a modified apparatus working under controlled atmosphere can be used. To our Knowledge there is very few publications describing the use of such modified cone calorimeters and providing data regarding the effect of ventilation on the fire properties. In the open literature it was reported end of the 1990's that substantial burning can occurred outside the test chamber when such a device is used, the amount of oxygen available to combustion exceeding the amount that was fed to the combustion chamber. In such a case (leading to post-buming outside the test chamber), it has been proposed to correct the experimental data by replacing the oxygen mass feeding rate by the actual rate of oxygen consumption. This paper analyses the proposed correction, and suggests that this might not be fully satisfactory by comparison to data obtained in another bench scale calorimeter with controlled atmosphere. The capacity of a Cone Calorimeter fitted with a controlled atmosphere device will be more in depth investigated in a new research project starting in 2007

    Synthesis of 3 H‐labeled sympathomimetic amines for neuronal mapping

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    The synthesis of two tritium labeled sympathomimetic amines, (R)‐(‐)‐phenylephrine and (1R,2S)‐(‐)‐ meta ‐hydroxyephedrine, is described. The tritium label was introduced into the aromatic ring in the final step by catalytic reductive dehalogenation of the corresponding iodinated precursor. (1R,2S)‐(‐)‐ meta ‐hydroxyephedrine was synthesized in four steps from commercially available metaraminol. A novel HPLC purification method provided the labeled compounds in a medium ready for direct animal evaluation. Chemical and radiochemical purity was ≥98%; specific activity was ≥ 22 Ci/mmol.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90370/1/2580280713_ftp.pd

    High-quality conforming hexahedral meshes of patient-specific abdominal aortic aneurysms including their intraluminal thrombi

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    In order to perform finite element (FE) analyses of patient-specific abdominal aortic aneurysms, geometries derived from medical images must be meshed with suitable elements. We propose a semi-automatic method for generating conforming hexahedral meshes directly from contours segmented from medical images. Magnetic resonance images are generated using a protocol developed to give the abdominal aorta high contrast against the surrounding soft tissue. These data allow us to distinguish between the different structures of interest. We build novel quadrilateral meshes for each surface of the sectioned geometry and generate conforming hexahedral meshes by combining the quadrilateral meshes. The three-layered morphology of both the arterial wall and thrombus is incorporated using parameters determined from experiments. We demonstrate the quality of our patient-specific meshes using the element Scaled Jacobian. The method efficiently generates high-quality elements suitable for FE analysis, even in the bifurcation region of the aorta into the iliac arteries. For example, hexahedral meshes of up to 125,000 elements are generated in less than 130 s, with 94.8 % of elements well suited for FE analysis. We provide novel input for simulations by independently meshing both the arterial wall and intraluminal thrombus of the aneurysm, and their respective layered morphologies

    Taurodontic teeth in cone beam computed tomography: pictorial review

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    Objective: Taurodontism is a developmental disorder with enlargement of the body of the tooth and lack of cervical constriction, which results in a large pulp chamber and small roots with the apical displacement of furcation. Taurodontism exists in deciduous, and definitive unilateral, and bilateral teeth. We found that taurodontism was also described in 67 syndromes. We proposed a review of the open access literature on taurodontism, a new clinical classification of taurodontic teeth with illustrations from free open access literature, and from our case serie of 15 patients. Material and methods: We performed a systematic search for articles with free full text about taurodontism. The search was performed by one observer in PubMed database. We found 168 articles, and after application of inclusion/exclusion criteria we finally selected 136 articles for the review. Results: we provided 34 figures of taurodontic teeth related to: 1) Unilateral mandibular first premolar, 2) Unilateral mandibular second premolar, 3) Bilateral mandibular first and second premolar, 4) Bilateral upper maxillary first premolars, 5) Bilateral mandibular second molars, 6) Bilateral upper maxillary second premolar and left first molar, 7) Bilateral upper maxillary third molars, 8) Bilateral upper maxillary first and second molars, 9) Bilateral upper maxillary first, second, and third molars, 10) Bilateral upper maxillary molars (third molars, second, and first left upper molars), and mandibular molars (first right, and left mandibular molars, right third molar), 11) Bilateral upper maxillary molars (first, second, third right, and left upper molars), and mandibular molars, 12) Unilateral first mandibular premolar with cleft, 13) Bilateral molars of the mandible and the upper maxilla (adolescent patient who received chemotherapy at the age of 3-years-old to treat retinoblastoma), 14) Unilateral first maxillary molar (Treacher-Collins syndrome). Conclusions: We proposed a new clinical classification of taurodontic teeth based on hypo-, meso-, and hypertaurodontism, and on different types of deciduous, and definitive teeth (42 boxes). We were first to provide free reference images for: 1) upper maxillary second premolar hypertaurodontism, 2) mandibular second premolar mesotaurodontism, 3) upper maxillary third molar meso-and hypertaurodontism, 4) mandibular first molar hypotaurodontism, 5) mandibular third molar mesotaurodontism. We were also first to freely illustrate taurodontism related with chemotherapy, cleft palate patients, and Treacher-Collins syndrome. Objective: Taurodontism is a developmental disorder with enlargement of the body of the tooth and lack of cervical constriction, which results in a large pulp chamber and small roots with the apical displacement of furcation. Taurodontism exists in deciduous, and definitive unilateral, and bilateral teeth. We found that taurodontism was also described in 67 syndromes. We proposed a review of the open access literature on taurodontism, a new clinical classification of taurodontic teeth with illustrations from free open access literature, and from our case serie of 15 patients. Material and methods: We performed a systematic search for articles with free full text about taurodontism. The search was performed by one observer in PubMed database. We found 168 articles, and after application of inclusion/exclusion criteria we finally selected 136 articles for the review. Results: we provided 34 figures of taurodontic teeth related to: 1) Unilateral mandibular first premolar, 2) Unilateral mandibular second premolar, 3) Bilateral mandibular first and second premolar, 4) Bilateral upper maxillary first premolars, 5) Bilateral mandibular second molars, 6) Bilateral upper maxillary second premolar and left first molar, 7) Bilateral upper maxillary third molars, 8) Bilateral upper maxillary first and second molars, 9) Bilateral upper maxillary first, second, and third molars, 10) Bilateral upper maxillary molars (third molars, second, and first left upper molars), and mandibular molars (first right, and left mandibular molars, right third molar), 11) Bilateral upper maxillary molars (first, second, third right, and left upper molars), and mandibular molars, 12) Unilateral first mandibular premolar with cleft, 13) Bilateral molars of the mandible and the upper maxilla (adolescent patient who received chemotherapy at the age of 3-years-old to treat retinoblastoma), 14) Unilateral first maxillary molar (Treacher-Collins syndrome). Conclusions: We proposed a new clinical classification of taurodontic teeth based on hypo-, meso-, and hypertaurodontism, and on different types of deciduous, and definitive teeth (42 boxes). We were first to provide free reference images for: 1) upper maxillary second premolar hypertaurodontism, 2) mandibular second premolar mesotaurodontism, 3) upper maxillary third molar meso-and hypertaurodontism, 4) mandibular first molar hypotaurodontism, 5) mandibular third molar mesotaurodontism. We were also first to freely illustrate taurodontism related with chemotherapy, cleft palate patients, and Treacher-Collins syndrome
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