1,963 research outputs found
Foreign civil aviation competition: 1976 summary and implications
A summary assessment is made of foreign civil aviation as it relates to the posture of the United States civil aviation industry. Major findings include: (1) Main competitors - European Economic Community (EEC) and Union of Soviet Socialist Republics (USSR). (2) Largest commercial market - Transport aircraft. (3) Current market status and projections - U.S. currently dominates the civil aviation market but foreign markets show greater growth trends. (4) Competitive comparisons - Status comparisons are made in technology (aerodynamics, structures and materials, propulsion, avionics, systems, design coordination, and manufacturing); production runs; marketing; and postsales support. The U.S. generally leads except in aerodynamics and propulsion. (5) Multinational ventures - Joint U.S. industry/foreign government development of advanced technology engines is well developed; airframe industry discussions are now underway. (6) Implications - Although the U.S., is currently preeminent in most areas, this may be only a temporary condition. Past U.S. success in aviation has provided many benefits to the nation. These benefits may be lost
Three and Two Colours Finite Density QCD at Strong Coupling: A New Look
Simulations in finite density, beta=0 lattice QCD by means of the
Monomer-Dimer-Polymer algorithm show a signal of first order transition at
finite temporal size. This behaviour agrees with predictions of the mean field
approximation, but is difficult to reconcile with infinite mass analytical
solution. The MDP simulations are considered in detail and severe convergence
problems are found for the SU(3) gauge group, in a wide region of chemical
potential. Simulations of SU(2) model show discrepancies with MDP results as
well.Comment: 18 pages, 9 figures, to appear in Nucl. Phys.
QCD at Finite Density and Color Superconductivity
Brief review of current status of the field.Comment: Invited talk at Lattice 99, Pisa, July 1999. 5 pages, 7 fig
On stoichiometry and intermixing at the spinel/perovskite interface in CoFe2O4/BaTiO3 thin films
The performance of complex oxide heterostructures depends primarily on the interfacial coupling of the two component structures. This interface character inherently varies with the synthesis method and conditions used since even small composition variations can alter the electronic, ferroelectric, or magnetic functional properties of the system. The focus of this article is placed on the interface character of a pulsed laser deposited CoFe2O4/BaTiO3 thin film. Using a range of state-of-the-art transmission electron microscopy methodologies, the roles of substrate morphology, interface stoichiometry, and cation intermixing are determined on the atomic level. The results reveal a surprisingly uneven BaTiO3 substrate surface formed after the film deposition and Fe atom incorporation in the top few monolayers inside the unit cell of the BaTiO3 crystal. Towards the CoFe2O4 side, a disordered region extending several nanometers from the interface was revealed and both Ba and Ti from the substrate were found to diffuse into the spinel layer. The analysis also shows that within this somehow incompatible composite interface, a different phase is formed corresponding to the compound Ba2Fe3Ti5O15, which belongs to the ilmenite crystal structure of FeTiO3 type. The results suggest a chemical activity between these two oxides, which could lead to the synthesis of complex engineered interfaces
Band gap bowing in NixMg1-xO.
Epitaxial transparent oxide NixMg1-xO (0 ≤ x ≤ 1) thin films were grown on MgO(100) substrates by pulsed laser deposition. High-resolution synchrotron X-ray diffraction and high-resolution transmission electron microscopy analysis indicate that the thin films are compositionally and structurally homogeneous, forming a completely miscible solid solution. Nevertheless, the composition dependence of the NixMg1-xO optical band gap shows a strong non-parabolic bowing with a discontinuity at dilute NiO concentrations of x  0.074 and account for the anomalously large band gap narrowing in the NixMg1-xO solid solution system
Strong coupling analysis of diquark condensation
The phenomenon of diquark condensation at non-zero baryon density and zero
temperature is analyzed in the strong coupling limit of lattice QCD. The
results indicate that there is attraction in the quark-quark channel also at
strong coupling, and that the attraction is more effective at high baryon
density, but for infinite coupling it is not enough to produce diquark
condensation. It is argued that the absence of diquark condensation is not a
peculiarity of the strong coupling limit, but persists at sufficiently large
finite couplings.Comment: 3 pages, 2 figures, Lattice2004(non-zero
Positioning the Destination Product-Can Regional Tourist Boards Learn from Private Sector Practice?
This article examines the role of positioning in the
marketing of a tourism destination. The study focuses on the current positioning strategies pursued by the Regional Tourist Boards (RTBs) in England. A recent nationwide consumer research study into short holiday destination choice in the UK revealed that consumers were confused by the regional product message. The evidence suggests that current RTB positioning strategies are failing to keep pace with the constantly evolving needs of the consumer. This
article explores the reasons for clearly positioning the destination product and suggests that, although RTBs could learn from marketing strategies employed in other sectors of the tourism industry, there are likely to be organisational and cultural barriers inhibiting this
learning curve
Internal Frame Dragging and a Global Analog of the Aharonov-Bohm Effect
It is shown that the breakdown of a {\it global} symmetry group to a discrete
subgroup can lead to analogues of the Aharonov-Bohm effect. At sufficiently low
momentum, the cross-section for scattering of a particle with nontrivial
charge off a global vortex is almost equal to (but definitely different from)
maximal Aharonov-Bohm scattering; the effect goes away at large momentum. The
scattering of a spin-1/2 particle off a magnetic vortex provides an amusing
experimentally realizable example.Comment: (14 pp
Bulk viscosity in a cold CFL superfluid
We compute one of the bulk viscosity coefficients of cold CFL quark matter in
the temperature regime where the contribution of mesons, quarks and gluons to
transport phenomena is Boltzmann suppressed. In that regime dissipation occurs
due to collisions of superfluid phonons, the Goldstone modes associated to the
spontaneous breaking of baryon symmetry. We first review the hydrodynamics of
relativistic superfluids, and remind that there are at least three bulk
viscosity coefficients in these systems. We then compute the bulk viscosity
coefficient associated to the normal fluid component of the superfluid. In our
analysis we use Son's effective field theory for the superfluid phonon, amended
to include scale breaking effects proportional to the square of the strange
quark mass m_s. We compute the bulk viscosity at leading order in the scale
breaking parameter, and find that it is dominated by collinear splitting and
joining processes. The resulting transport coefficient is zeta=0.011 m_s^4/T,
growing at low temperature T until the phonon fluid description stops making
sense. Our results are relevant to study the rotational properties of a compact
star formed by CFL quark matter.Comment: 19 pages, 2 figures; one reference added, version to be published in
JCA
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