2,076 research outputs found

    FLASH: Randomized Algorithms Accelerated over CPU-GPU for Ultra-High Dimensional Similarity Search

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    We present FLASH (\textbf{F}ast \textbf{L}SH \textbf{A}lgorithm for \textbf{S}imilarity search accelerated with \textbf{H}PC), a similarity search system for ultra-high dimensional datasets on a single machine, that does not require similarity computations and is tailored for high-performance computing platforms. By leveraging a LSH style randomized indexing procedure and combining it with several principled techniques, such as reservoir sampling, recent advances in one-pass minwise hashing, and count based estimations, we reduce the computational and parallelization costs of similarity search, while retaining sound theoretical guarantees. We evaluate FLASH on several real, high-dimensional datasets from different domains, including text, malicious URL, click-through prediction, social networks, etc. Our experiments shed new light on the difficulties associated with datasets having several million dimensions. Current state-of-the-art implementations either fail on the presented scale or are orders of magnitude slower than FLASH. FLASH is capable of computing an approximate k-NN graph, from scratch, over the full webspam dataset (1.3 billion nonzeros) in less than 10 seconds. Computing a full k-NN graph in less than 10 seconds on the webspam dataset, using brute-force (n2Dn^2D), will require at least 20 teraflops. We provide CPU and GPU implementations of FLASH for replicability of our results

    Cosmic ray intensity distribution perpendicular to solar equatorial plane at 1 A.U. during 1978-83

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    The distribution of cosmic ray intensity perpendicular to solar equatorial plane, was investigated by using its yearly variation with respect to the heliolatitudinal position of the Earth, for the two intervals 1978 to 1980 and 1981 to 1983. The monthly mean values of two high latitude stations along with the solar and geomagnetic indices are used to derive the cosmic ray intensity distribution free from the changes due to variation in solar activity. The correction is found to be significant only during the interval 1976 to 1980. The results indicate a significant linear increase in cosmic ray intensity from north to south of solar equator, contrary to that observed during 1973 to 1975. No symmetrical gradients are found during the period of study, in agreement with earlier results

    A Microprocessor-Based System for Monitoring Gas Turbines

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    The development and testing of hardware and software for a microprocessor-based monitoring system for gas turbines is described in this paper. The operators of gas turbines can be trained to monitor running hours, slip between high and low pressure compressor spools and torque on the reduction gear-box under various conditions ofoperation. The system will replace the traditional method of monitoring these parameters which are more time consuming and error prone

    Structural and antimicrobial studies of coordination compounds of VO(II), Co(II), Ni(II) and Cu(II) with some Schiff bases involving 2-amino-4-chlorophenol

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    Complexes of tailor-made ligands with life essential metal ions may be an emerging area to answer the problem of multi-drug resistance (MDR). The coordination complexes of VO(II), Co(II), Ni(II) and Cu(II) with the Schiff bases derived from 2-hydroxyacetophenone/2-chlorobenzaldehyde with 2-ami¬no-4-chlorophenol were synthesized and characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, ESR, FAB mass, thermal and magnetic susceptibility measurements. The FAB mass and thermal data show degradation of the complexes. The ligand A (2-hydroxyacetophenone-2amino-4-chlorophenol) behaved as tridentate and ligand B (2-chlorobenzylidene-2-amino-4-chlorophenol) as bidentate, coordinating through O and N donors. The complexes [VO(A)(H2O)]×xH2O, [M(A)(H2O)n]×xH2O for Co and Ni, [Cu(A)(H2O)] and [VO(B)2]×xH2O, [M(B)2(H2O)n] for Co and Cu and [Ni(B)2] exhibited coordination numbers 4, 5 or 6. X-ray powder diffraction data (a = 11.00417 Å, b = 11.706081 Å and c = 54.46780 Å) showed that [Cu(CACP)2(H2O)2], complex 8, crystallized in the orthorhombic system. The in vitro biological screening effects of the investigated compounds were tested against the bacteria Escherichia coli, Staphylococcus aureus and Streptococcus fecalis and the fungi Aspergillus niger, Trichoderma polysporum and Candida albicans by the serial dilution method. A comparative study of the MIC values of the Schiff base and their [M(B)2(H2O)2] complexes (Co(II), complex 6 and Cu(II), complex 8), indicated that the metal complexes exhibited a higher or lower antimicrobial activity than 2-chlorobenzylidene-2-amino-4-chlorophenol as the free ligand (B)

    Effects of chromium on the immune system

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    Chromium is a naturally occurring heavy metal found commonly in the environment in trivalent, Cr(III), and hexavalent, Cr(VI), forms. Cr(VI) compounds have been declared as a potent occupational carcinogen among workers in chrome plating, stainless steel, and pigment industries. The reduction of Cr(VI) to Cr(III) results in the formation of reactive intermediates that together with oxidative stress oxidative tissue damage and a cascade of cellular events including modulation of apoptosis regulatory gene p53, contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. On the other hand, chromium is an essential nutrient required to promote the action of insulin in body tissues so that the body can use sugars, proteins and fats. Chromium is of significant importance in altering the immune response by immunostimulatory or immunosuppressive processes as shown by its effects on T and B lymphocytes, macrophages, cytokine production and the immune response that may induce hypersensitivity reactions. This review gives an overview of the effects of chromium on the immune system of the body

    Simple Analytical Particle and Kinetic Energy Densities for a Dilute Fermionic Gas in a d-Dimensional Harmonic Trap

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    We derive simple analytical expressions for the particle density ρ(r)\rho(r) and the kinetic energy density τ(r)\tau(r) for a system of noninteracting fermions in a dd-dimensional isotropic harmonic oscillator potential. We test the Thomas-Fermi (TF, or local-density) approximation for the functional relation τ[ρ]\tau[\rho] using the exact ρ(r)\rho(r) and show that it locally reproduces the exact kinetic energy density τ(r)\tau(r), {\it including the shell oscillations,} surprisingly well everywhere except near the classical turning point. For the special case of two dimensions (2D), we obtain the unexpected analytical result that the integral of τTF[ρ(r)]\tau_{TF}[\rho(r)] yields the {\it exact} total kinetic energy.Comment: 4 pages, 4 figures; corrected versio

    Electromagnetic transition from the 4+^+ to 2+^+ resonance in 8^8Be measured via the radiative capture in 4^4He+4^4He

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    An earlier measurement on the 4+^+ to 2+^+ radiative transition in 8^8Be provided the first electromagnetic signature of its dumbbell-like shape. However, the large uncertainty in the measured cross section does not allow a stringent test of nuclear structure models. The present paper reports a more elaborate and precise measurement for this transition, via the radiative capture in the 4^4He+4^4He reaction, improving the accuracy by about a factor of three. The {\it ab initio} calculations of the radiative transition strength with improved three-nucleon forces are also presented. The experimental results are compared with the predictions of the alpha cluster model and {\it ab initio} calculations.Comment: 5 pages and 7 figures, Submitted to Physical Review Letter

    Role of the cluster structure of 7^7Li in the dynamics of fragment capture

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    Exclusive measurements of prompt γ\gamma-rays from the heavy-residues with various light charged particles in the 7^7Li + 198^{198}Pt system, at an energy near the Coulomb barrier (E/VbV_b \sim 1.6) are reported. Recent dynamic classical trajectory calculations, constrained by the measured fusion, α\alpha and tt capture cross-sections have been used to explain the excitation energy dependence of the residue cross-sections. These calculations distinctly illustrate a two step process, breakup followed by fusion in case of the capture of tt and α\alpha clusters; whereas for 6^{6}He + pp and 5^{5}He + dd configurations, massive transfer is inferred to be the dominant mechanism. The present work clearly demonstrates the role played by the cluster structures of 7^7Li in understanding the reaction dynamics at energies around the Coulomb barrier.Comment: 6 pages, 4 figures, Accepted for publication in Phys. Letts.
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