6,358 research outputs found
Supercritical multicomponent solvent coal extraction
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
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)
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 GeV in
which the cosmic baryon asymmetry originates from an initial asymmetry of an
anomalous -charge, and soft leptogenesis reembodies in -genesis.Comment: References updated. Some minor corrections to match the published
versio
Mount St. Helens aerosol evolution
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
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
Nonmagnetic Zn impurities are known to strongly suppress superconductivity.
We review their effects on the spin excitation spectrum in , 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}
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
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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