7,833 research outputs found

    Atomic spectrometry update. Clinical and biological materials, foods and beverages

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    This review discusses developments in elemental mass spectrometry, atomic absorption, emission and fluorescence, XRF and LIBS, as applied to the analysis of specimens of clinical interest, foods and beverages. Sample preparation procedures and quality assurance are also included.</p

    Breeding for improved nitrogen use efficiency in oilseed rape

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    Oilseed rape has a high requirement for nitrogen (N) fertiliser relative to its seed yield. This paper uses published and unpublished work to explore the extent to which the N use efficiency (seed yield Ă· N supply) of oilseed rape could be improved without reducing seed yield. It was estimated that if the concentration of N in the stem and pod wall at crop maturity could be reduced from 1.0 to 0.6%, the root length density increased to 1 cm/cm3 to 100 cm soil depth and the post flowering N uptake increased by 20 kg N/ha then the fertiliser requirement could be reduced from 191 to 142 kg N/ha and the N use efficiency could be increased from 15.2 to 22.4 kg of seed dry matter per kg N. Genetic variation was found for all of the traits that were estimated to be important for N use efficiency. This indicates that there is significant scope for plant breeders to reduce N use efficiency in oilseed rape

    The Extraordinarily Rapid Expansion of the X-ray Remnant of Kepler's Supernova (SN1604)

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    Four individual high resolution X-ray images from ROSAT and the Einstein Observatory have been used to measure the expansion rate of the remnant of Kepler's supernova (SN 1604). Highly significant measurements of the expansion have been made for time baselines varying from 5.5 yrs to 17.5 yrs. All measurements are consistent with a current expansion rate averaged over the entire remnant of 0.239 (+/-0.015) (+0.017,-0.010) % per yr, which, when combined with the known age of the remnant, determines the expansion parameter m, defined as R∝tmR\propto t^m, to be 0.93 (+/-0.06) (+0.07,-0.04). The error bars on these results include both statistical (first set of errors) and systematic (second set) uncertainty. According to this result the X-ray remnant is expanding at a rate that is remarkably close to free expansion and nearly twice as fast as the mean expansion rate of the radio remnant. The expansion rates as a function of radius and azimuthal angle are also presented based on two ROSAT images that were registered to an accuracy better than 0.5 arcseconds. Significant radial and azimuthal variations that appear to arise from the motion of individual X-ray knots are seen. The high expansion rate of the X-ray remnant appears to be inconsistent with currently accepted dynamical models for the evolution of Kepler's SNR.Comment: 14 pages, including 7 postscript figs, LaTeX, emulateapj. Accepted by Ap

    Capital Budgeting for Small Businesses: An Appropriate Modification of Net Present Value

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    This paper sets forth a capital budgeting technique that is both theoretically correct and sensitive to the special financing needs of the small business. This technique involves evaluating cash flows and determining if they are sufficient to meet the loan payment schedule. A sufficient amount of cash flow must remain after debt obligations are met to compensate the equity investment. Net operating cash flows are discounted at the cost of equity while the tax shield from interest and depreciation is discounted at the cost of debt

    Stereocontrolled Synthesis of Amino‐Substituted Carbocycles by Pd‐Catalyzed Alkene Carboamination Reactions

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    Amino‐substituted alkylidenecyclopentanes were synthesized through a stereoselective intermolecular Pd‐catalyzed alkene carboamination reaction between alkenyl triflates bearing a pendant alkene and exogenous amine nucleophiles. The reactions are effective with a range of different substrate combinations, and proceed with generally high diastereoselectivity. Use of (S)‐tBuPhox as the ligand in reactions of achiral substrates provides enantioenriched products with up to 98.5:1.5 e.r.Adding amines: The palladium‐catalyzed coupling of amines with enol triflates derived from 2‐allylcycloalkanones provides substituted alkylidenecyclopentylamine derivatives in good yield with high levels of stereoselectivity. Achiral substrates are transformed with up to 98.5:1.5 e.r.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136662/1/chem201700466_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136662/2/chem201700466.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136662/3/chem201700466-sup-0001-misc_information.pd

    A Proposed Capital Budgeting Technique For Liquidity Constrained Small Businesses

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    Although the ad vantages of capital budgeting models using discounted cash flaws are well known, small businesses continue to rely on non-discounted techniques in making capital budgeting decisions. This paper analyzes the financial environment in which small businesses operate that makes traditional capital budgeting models inappropriate. A capital budgeting technique is developed that is sensitive to the needs of small businesses and also meets the three-fold criteria for capital budgeting methods.
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