1,229 research outputs found

    A partitioning strategy for nonuniform problems on multiprocessors

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    The partitioning of a problem on a domain with unequal work estimates in different subddomains is considered in a way that balances the work load across multiple processors. Such a problem arises for example in solving partial differential equations using an adaptive method that places extra grid points in certain subregions of the domain. A binary decomposition of the domain is used to partition it into rectangles requiring equal computational effort. The communication costs of mapping this partitioning onto different microprocessors: a mesh-connected array, a tree machine and a hypercube is then studied. The communication cost expressions can be used to determine the optimal depth of the above partitioning

    Ricci Collineations for Non-Degenerate, Diagonal and Spherically Symmetric Ricci Tensors

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    The expression of the vector field generator of a Ricci Collineation for diagonal, spherically symmetric and non-degenerate Ricci tensors is obtained. The resulting expressions show that the time and radial first derivatives of the components of the Ricci tensor can be used to classify the collineation, leading to 64 families. Some examples illustrate how to obtain the collineation vector

    Malignancy with unknown primary presenting as acute cardiac tamponade: a case report

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    A case report of a patient presenting in cardiac tamponade that was subsequently diagnosed as being secondary to malignancy of unknown primary. The patient was treated by urgent pericardiocentesis, followed by subsequent formation of a subxiphoid pericardial window. He was discharged home and given palliative chemotherapy. Malignant pericardial effusions are common, but it is rare for a patient to present in cardiac tamponade as the presenting feature of an unidentified malignancy. The causes, diagnosis and treatment of cardiac tamponade are discussed

    Antimicrobial and phytotoxic screening of various fractions of Sonchus asper

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    Sonchus asper is used in the treatment of many diseases ethnopharmacologically in Pakistan. In the present manuscript we demonstrate the antimicrobial and phytotoxic effects of various fractions of S.asper. Six (6) different bacteria (Escherichia coli, Bacillus subtilis, Micrococcus luteus, klebsiella pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa) are used in the screening of extract as well as 4 strains of fungi are characterized. Raddish root inhibition assay was used for phytotoxic screening. Methanolic fraction of S. asper showed best activities in all of assays, in inhibition of microbes and phytotoxic activities. The potency of these activities is due to the presence of bioactive flavonoids, saponins and phenolic compounds

    The Tera Multithreaded Architecture and Unstructured Meshes

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    The Tera Multithreaded Architecture (MTA) is a new parallel supercomputer currently being installed at San Diego Supercomputing Center (SDSC). This machine has an architecture quite different from contemporary parallel machines. The computational processor is a custom design and the machine uses hardware to support very fine grained multithreading. The main memory is shared, hardware randomized and flat. These features make the machine highly suited to the execution of unstructured mesh problems, which are difficult to parallelize on other architectures. We report the results of a study carried out during July-August 1998 to evaluate the execution of EUL3D, a code that solves the Euler equations on an unstructured mesh, on the 2 processor Tera MTA at SDSC. Our investigation shows that parallelization of an unstructured code is extremely easy on the Tera. We were able to get an existing parallel code (designed for a shared memory machine), running on the Tera by changing only the compiler directives. Furthermore, a serial version of this code was compiled to run in parallel on the Tera by judicious use of directives to invoke the "full/empty" tag bits of the machine to obtain synchronization. This version achieves 212 and 406 Mflop/s on one and two processors respectively, and requires no attention to partitioning or placement of data issues that would be of paramount importance in other parallel architectures

    Evaluating the efficacy of tuberculosis advocacy, communication and social mobilization (ACSM) activities in Pakistan : a cross-sectional study

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    BACKGROUND: Tuberculosis (TB) continues to be a major public health and development problem within many low- and middle-income countries. Although Advocacy, Communication and Social Mobilization (ACSM) activities have been undertaken in high TB burden countries to remediate these issues, there is little empirical evidence of the efficacy of these approaches. The purpose of this study was therefore to examine the efficacy of an ACSM program undertaken within Pakistan. Pakistan was chosen because it has received considerable funding for ACSM related activities and is one of 22 high-burden TB countries. METHODS: The program was evaluated by surveying a stratified random sample of 2,400 participants across 57 districts of Pakistan. Participants were categorized into one of three groups: aware of both media and community ACSM activities (Aware(Media)&(Community)), aware of ACSM media activities only (Aware(Media)), or unaware of any ACSM activities (Unaware(Media)&(Community)). RESULTS: Independent measures ANCOVA revealed complex differences in knowledge, attitudes, and intended behaviors towards TB between the three groups. In general, Unaware(Media)&(Community) cases had a poorer understanding of TB and its treatment, whilst awareness of ACSM activities was highest among literate and urban dwelling Pakistanis. Preferred sources of TB information were also found to vary by gender, geographic location, and literacy. CONCLUSIONS: Whilst highlighting improvements in knowledge and attitudes toward TB, the results also provide invaluable insights into areas where further work needs to be done to address deficits in TB understanding, particularly among rural and illiterate Pakistanis. Equally important, the findings have implications for future TB ACSM initiatives in Pakistan in terms of leveraging the preferred media channels of key demographic segments and exploring the degree to which exposure to multiple channels of communication may have an additive effect on health knowledge

    Conformal Ricci collineations of static spherically symmetric spacetimes

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    Conformal Ricci collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating conformal Ricci collineations is found when the Ricci tensor is non-degenerate, in which case the number of independent conformal Ricci collineations is \emph{fifteen}; the maximum number for 4-dimensional manifolds. In the degenerate case it is found that the static spherically symmetric spacetimes always have an infinite number of conformal Ricci collineations. Some examples are provided which admit non-trivial conformal Ricci collineations, and perfect fluid source of the matter

    Phytotoxic characterization of various fractions of Launaea procumbens

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    Allelopathic screening of various fractions of Launaea procumbens, collected from Wah Cantt (Punjab) Pakistan, was conceded to identify potent allelopathic fraction for future phytochemical analyses. For this purpose, radish root inhibition method was used to test allelopathic potential. Two different concentrations of 100 ppm and 1000 ppm of Launaea procumbens were used in this study. Methanolic and ethyl acetate fraction potently inhibited root and radical growth; comparative to other fractions, it might be due to the presence of bioactive allelochemicals. Based on this screening, both of these fractions were recommended for future bioassay guided isolation of allelochemicals.Key words: Launaea procumbens, radish seeds, root inhibition, Launaea procumbens methanolic fraction

    Frame Interpolation for Cloud-Based Mobile Video Streaming

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    © 2016 IEEE. Cloud-based High Definition (HD) video streaming is becoming popular day by day. On one hand, it is important for both end users and large storage servers to store their huge amount of data at different locations and servers. On the other hand, it is becoming a big challenge for network service providers to provide reliable connectivity to the network users. There have been many studies over cloud-based video streaming for Quality of Experience (QoE) for services like YouTube. Packet losses and bit errors are very common in transmission networks, which affect the user feedback over cloud-based media services. To cover up packet losses and bit errors, Error Concealment (EC) techniques are usually applied at the decoder/receiver side to estimate the lost information. This paper proposes a time-efficient and quality-oriented EC method. The proposed method considers H.265/HEVC based intra-encoded videos for the estimation of whole intra-frame loss. The main emphasis in the proposed approach is the recovery of Motion Vectors (MVs) of a lost frame in real-time. To boost-up the search process for the lost MVs, a bigger block size and searching in parallel are both considered. The simulation results clearly show that our proposed method outperforms the traditional Block Matching Algorithm (BMA) by approximately 2.5 dB and Frame Copy (FC) by up to 12 dB at a packet loss rate of 1%, 3%, and 5% with different Quantization Parameters (QPs). The computational time of the proposed approach outperforms the BMA by approximately 1788 seconds

    Weighing the Milky Way

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    We describe an experiment to measure the mass of the Milky Way galaxy. The experiment is based on calculated light travel times along orthogonal directions in the Schwarzschild metric of the Galactic center. We show that the difference is proportional to the Galactic mass. We apply the result to light travel times in a 10cm Michelson type interferometer located on Earth. The mass of the Galactic center is shown to contribute 10^-6 to the flat space component of the metric. An experiment is proposed to measure the effect.Comment: 10 pages, 1 figur
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