1,696,209 research outputs found
Raman Fingerprint of Charged Impurities in Graphene
We report strong variations in the Raman spectra for different single-layer
graphene samples obtained by micromechanical cleavage, which reveals the
presence of excess charges, even in the absence of intentional doping. Doping
concentrations up to ~10^13 cm-2 are estimated from the G peak shift and width,
and the variation of both position and relative intensity of the second order
2D peak. Asymmetric G peaks indicate charge inhomogeneity on the scale of less
than 1 micron.Comment: 3 pages, 5 figure
Interoperability of Information Systems and Heterogenous Databases Using XML
Interoperabilily of information systerrrs is the most critical issue facing businesse!
that need to access information from multiple idormution systems on
tlifferent environments ancl diverse platforms. Interoperability has been a basic
requirement for the modern information systems in a competitive and volatile
business environment, particularly with the advent of distributed network system
and the growing relevance of inter-network communications. Our objective
in tltis paper is to develop a comprehensiveframework tofacilitate interoperability
smong distributed and heterogeneous information systems and to develop prototype
software to validate tlte application of XML in interoperability of infurmation
systems and databases
Quasi-Local Formulation of Non-Abelian Finite-Element Gauge Theory
Recently it was shown how to formulate the finite-element equations of motion
of a non-Abelian gauge theory, by gauging the free lattice difference
equations, and simultaneously determining the form of the gauge
transformations. In particular, the gauge-covariant field strength was
explicitly constructed, locally, in terms of a path ordered product of
exponentials (link operators). On the other hand, the Dirac and Yang-Mills
equations were nonlocal, involving sums over the entire prior lattice. Earlier,
Matsuyama had proposed a local Dirac equation constructed from just the
above-mentioned link operators. Here, we show how his scheme, which is closely
related to our earlier one, can be implemented for a non-Abelian gauge theory.
Although both Dirac and Yang-Mills equations are now local, the field strength
is not. The technique is illustrated with a direct calculation of the current
anomalies in two and four space-time dimensions. Unfortunately, unlike the
original finite-element proposal, this scheme is in general nonunitary.Comment: 19 pages, REVTeX, no figure
TOWARDS A FUTURISTIC EDUCATIONAL DEVELOPMENT IN NIGERIA
Majority of the nations of the world were colonized and went through wars at various times, but
had turned around their fortunes through economic and educational reforms. In Nigeria however,
there had been series of educational reforms from: 7/6-5-4 to 6-3-3-4 and now 9-3-4 system.
Similarly, the recent reform in the higher education sector which has resulted into the conversion
of the nation’s higher technical educational institutions to degree awarding universities, which
arose largely from the disparity between the graduates of the two institutions in the labor market
and the fallen standard of education.
This paper presents a critical review of the various educational reforms with a view to designing
a viable educational model based on the examples of some developed and developing nations. It
attempts to proffer solutions to some of the existing problems
ASCA and ROSAT observations of NGC5548: discrepant spectral indices
We report on simultaneous ASCA and ROSAT observations of the Seyfert galaxy
NGC5548 made during the ASCA Performance Verification phase. Spectral features
due to a warm absorber and reflection are clearly seen in the X-ray spectra. We
find that the continuum spectral shape differs between the ASCA and ROSAT
datasets. The photon-index obtained from the ROSAT PSPC exceeds that from the
ASCA SIS about 0.4. The discrepancy is clear even in the 0.5-2 keV energy band
over which both detectors are sensitive. The spectra cannot be made consistent
by choosing a more complex model. The problem likely lies in the response curve
(estimated effective area) of one, or both, detectors. There may be important
consequences for a wide range of published results.Comment: 9 pages, accepted for publication in MNRA
Finite Element Flow Simulations of the EUROLIFT DLR-F11 High Lift Configuration
This paper presents flow simulation results of the EUROLIFT DLR-F11
multi-element wing configuration, obtained with a highly scalable finite
element solver, PHASTA. This work was accomplished as a part of the 2nd high
lift prediction workshop. In-house meshes were constructed with increasing mesh
density for analysis. A solution adaptive approach was used as an alternative
and its effectiveness was studied by comparing its results with the ones
obtained with other meshes. Comparisons between the numerical solution obtained
with unsteady RANS turbulence model and available experimental results are
provided for verification and discussion. Based on the observations, future
direction for adaptive research and simulations with higher fidelity turbulence
models is outlined.Comment: 52nd Aerospace Sciences Meetin
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