14,182 research outputs found

    The effect of tetrathionate on the stability and immunological properties of muscle triosephosphate dehydrogenases

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    Tetrathionate effect on stability and immunological properties of muscle triosephosphate dehydrogenase

    Galaxy pairs as a probe for mergers at z ~ 2

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    In this work I investigate the redshift evolution of pair fraction of a sample of 196 massive galaxies from z = 0 to 3, selected from the COSMOS field. We find that on average a massive galaxy undergoes ~ 1.1 \pm 0.5 major merger since z = 3. I will review the current limitations of using the pair fraction as a probe for quantifying the impact of mergers on galaxy evolution. This work is based on the paper Man et al. (2011).Comment: 4 pages; to appear on the Conference Proceedings for "Galaxy Mergers in an Evolving Universe", held in Hualien, Taiwan (October 2011

    A comparative study of the evolution of enzymes and nucleic acids Semiannual progress report, 1 May - 30 Nov. 1967

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    Immunological and enzymological approaches to evolution of enzymes and nucleic acid

    Using 21-cm absorption surveys to measure the average HI spin temperature in distant galaxies

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    We present a statistical method for measuring the average HI spin temperature in distant galaxies using the expected detection yields from future wide-field 21cm absorption surveys. As a demonstrative case study we consider a simulated all-southern-sky survey of 2-h per pointing with the Australian Square Kilometre Array Pathfinder for intervening HI absorbers at intermediate cosmological redshifts between z=0.4z = 0.4 and 11. For example, if such a survey yielded 10001000 absorbers we would infer a harmonic-mean spin temperature of T‾spin∼100\overline{T}_\mathrm{spin} \sim 100K for the population of damped Lyman α\alpha (DLAs) absorbers at these redshifts, indicating that more than 5050 per cent of the neutral gas in these systems is in a cold neutral medium (CNM). Conversely, a lower yield of only 100 detections would imply T‾spin∼1000\overline{T}_\mathrm{spin} \sim 1000K and a CNM fraction less than 1010 per cent. We propose that this method can be used to provide independent verification of the spin temperature evolution reported in recent 21cm surveys of known DLAs at high redshift and for measuring the spin temperature at intermediate redshifts below z≈1.7z \approx 1.7, where the Lyman-α\alpha line is inaccessible using ground-based observatories. Increasingly more sensitive and larger surveys with the Square Kilometre Array should provide stronger statistical constraints on the average spin temperature. However, these will ultimately be limited by the accuracy to which we can determine the HI column density frequency distribution, the covering factor and the redshift distribution of the background radio source population.Comment: 11 pages, 9 figures, 1 table. Proof corrected versio

    Dual-doped thermographic phosphor particles as surrogates for green fluorescent protein-labeled cells in tests of cytometric neurocatheters

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    We investigated the laser-induced fluorescence of particles of a compound thermographic phosphorLa2O2S:Eu(1%) and Gd2O2S:Eu(1%) to see if they can serve as a surrogate for cells transfected with the green fluorescent protein, in tests of neurocatheters used for intraparenchymal celldelivery. At an excitation wavelength of 337 nm and a concentration of ≈2×106 particles ml−1, the resulting slurries produced fluorescence intensities at 625 nm that were within a factor of 2 of those produced by similar number densities of relevant cells, thus suggesting the utility of this approach

    Economic Feasibility of Commercial Algae Oil Production in the United States

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    A Monte Carlo simulation model was constructed to analyze the economic feasibility of growing algae as a renewable fuel source. Increasing growth rates, pond water depth, oil content, and facility size are important for ensuring the economic viability of a commercial algae facility.algae, renewable, fuel, feedstock, microalgae, Agribusiness, Agricultural and Food Policy, Crop Production/Industries, Production Economics, Resource /Energy Economics and Policy, Risk and Uncertainty,

    Ab Initio Liquid Hydrogen Muon Cooling Simulations with ELMS in ICOOL

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    This paper presents new theoretical results on the passage of muons through liquid hydrogen which have been confirmed in a recent experiment. These are used to demonstrate that muon bunches may be compressed by ionisation cooling more effectively than suggested by previous calculations. Muon cooling depends on the differential cross section for energy loss and scattering of muons. We have calculated this cross section for liquid H2 from first principles and atomic data, avoiding traditional assumptions. Thence, 2-D probability maps of energy loss and scattering in mm-scale thicknesses are derived by folding, and stored in a database. Large first-order correlations between energy loss and scattering are found for H2, which are absent in other simulations. This code is named ELMS, Energy Loss & Multiple Scattering. Single particle trajectories may then be tracked by Monte Carlo sampling from this database on a scale of 1 mm or less. This processor has been inserted into the cooling code ICOOL. Significant improvements in 6-D muon cooling are predicted compared with previous predictions based on GEANT. This is examined in various geometries. The large correlation effect is found to have only a small effect on cooling. The experimental scattering observed for liquid H2 in the MUSCAT experiment has recently been reported to be in good agreement with the ELMS prediction, but in poor agreement with GEANT simulation.Comment: 6 pages, 3 figure

    Reconstruction of deglacial sea surface temperatures in the tropical Pacific from selective analysis of a fossil coral

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    The Sr/Ca of coral skeletons demonstrates potential as an indicator of sea surface temperatures (SSTs). However, the glacial-interglacial SST ranges predicted from Sr/Ca of fossil corals are usually higher than from other marine proxies. We observed infilling of secondary aragonite, characterised by high Sr/Ca ratios, along intraskeletal pores of a fossil coral from Papua New Guinea that grew during the penultimate deglaciation (130 +/- 2 ka). Selective microanalysis of unaltered areas of the fossil coral indicates that SSTs at similar to 130 ka were &lt;= 1 degrees C cooler than at present in contrast with bulk measurements ( combining infilled and unaltered areas) which indicate a difference of 6-7 degrees C. The analysis of unaltered areas of fossil skeletons by microprobe techniques may offer a route to more accurate reconstruction of past SSTs.</p
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