6,358 research outputs found

    Supercritical multicomponent solvent coal extraction

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    The yield of organic extract from the supercritical extraction of coal with larger diameter organic solvents such as toluene is increased by use of a minor amount of from 0.1 to 10% by weight of a second solvent such as methanol having a molecular diameter significantly smaller than the average pore diameter of the coal

    Dynamic Project Control Utilising a New Approach to Project Control

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    A new system has been developed for dynamic project management and control known as Planning Orientation Evaluation Methods (POEM) which has been considered as a core project evaluation system incorporating cost and time analysis. The performance control gives the manager a direct influence on the project completion date and rate of spend

    Leptogenesis from Soft Supersymmetry Breaking (Soft Leptogenesis)

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    Soft leptogenesis is a scenario in which the cosmic baryon asymmetry is produced from a lepton asymmetry generated in the decays of heavy sneutrinos (the partners of the singlet neutrinos of the seesaw) and where the relevant sources of CP violation are the complex phases of soft supersymmetry-breaking terms. We explain the motivations for soft leptogenesis, and review its basic ingredients: the different CP-violating contributions, the crucial role played by thermal corrections, and the enhancement of the efficiency from lepton flavour effects. We also discuss the high temperature regime T>107T > 10^7 GeV in which the cosmic baryon asymmetry originates from an initial asymmetry of an anomalous RR-charge, and soft leptogenesis reembodies in RR-genesis.Comment: References updated. Some minor corrections to match the published versio

    Mount St. Helens aerosol evolution

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    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mount St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months

    Healthcare Facilities in Nigeria: Redefining Standards and Developing Performance Benchmarks for the Professionalisation of FM Practices, Professionalism and ethics in construction: Improving the global industry

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    Healthcare in Nigeria is delivered by three tiers of government: the federal, state, and local government. Public hospital buildings suffer as facilities management (FM) functions are often neglected with significant effect on the operation of public hospitals in Nigeria. Most government hospitals have no tools for measuring FM performance. The aim of the study is to propose a performance measurement framework by redefining standards and developing performance benchmarks to improve current practices and to professionalise FM. The research adopted mixed qualitative and quantitative approaches to explore key issues and barriers to FM practices with stakeholders responsible for the management of hospital assets. The findings provided pointers on how to develop performance measurement in FM. Adoption of the FM performance measurement framework will assist policy makers in public hospitals in Nigeria to drive key organisational changes in the way assets are managed to support healthcare delivery and the professionalisation of FM

    Magnetic resonance peak and nonmagnetic impurities

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    Nonmagnetic Zn impurities are known to strongly suppress superconductivity. We review their effects on the spin excitation spectrum in YBa2Cu3O7\rm YBa_2Cu_3O_{7}, as investigated by inelastic neutron scattering measurements.Comment: Proceedings of Mato Advanced Research Workshop BLED 2000. To appear in Nato Science Series: B Physic

    Superconductivity-Induced Anomalies in the Spin Excitation Spectra of Underdoped YBa_2 Cu_3 O_{6+x}

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    Polarized and unpolarized neutron scattering has been used to determine the effect of superconductivity on the magnetic excitation spectra of YBa_2 Cu_3 O_{6.5} (T_c = 52K) and YBa_2 Cu_3 O_{6.7} (T_c = 67K). Pronounced enhancements of the spectral weight centered around 25 meV and 33 meV, respectively, are observed below T_c in both crystals, compensated predominantly by a loss of spectral weight at higher energies. The data provide important clues to the origin of the 40 meV magnetic resonance peak in YBa_2 Cu_3 O_7.Comment: LaTex, 4 pages, 4 ps figures. to appear in Phys. Rev. Let

    The Afterglow and Environment of the Short GRB111117A

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    We present multi-wavelength observations of the afterglow of the short GRB111117A, and follow-up observations of its host galaxy. From rapid optical and radio observations we place limits of r \gtrsim 25.5 mag at \deltat \approx 0.55 d and F_nu(5.8 GHz) < 18 \muJy at \deltat \approx 0.50 d, respectively. However, using a Chandra observation at t~3.0 d we locate the absolute position of the X-ray afterglow to an accuracy of 0.22" (1 sigma), a factor of about 6 times better than the Swift-XRT position. This allows us to robustly identify the host galaxy and to locate the burst at a projected offset of 1.25 +/- 0.20" from the host centroid. Using optical and near-IR observations of the host galaxy we determine a photometric redshift of z=1.3 (+0.3,-0.2), one of the highest for any short GRB, and leading to a projected physical offset for the burst of 10.5 +/- 1.7 kpc, typical of previous short GRBs. At this redshift, the isotropic gamma-ray energy is E_{gamma,iso} \approx 3\times10^51 erg (rest-frame 23-2300 keV) with a peak energy of E_{pk} \approx 850-2300 keV (rest-frame). In conjunction with the isotropic X-ray energy, GRB111117A appears to follow our recently-reported E_x,iso-E_gamma,iso-E_pk universal scaling. Using the X-ray data along with the optical and radio non-detections we find that for a blastwave kinetic energy of E_{K,iso} \approx E_{gamma,iso}, the circumburst density is n_0 \sim 3x10^(-4)-1 cm^-3 (for a range of epsilon_B=0.001-0.1). Similarly, from the non-detection of a break in the X-ray light curve at t<3 d, we infer a minimum opening angle for the outflow of theta_j> 3-10 degrees (depending on the circumburst density). We conclude that Chandra observations of short GRBs are effective at determining precise positions and robust host galaxy associations in the absence of optical and radio detections.Comment: ApJ accepted versio
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