12,396 research outputs found
Oil Prices and the Impact of Rising Economies
•The first commercial oil well was drilled in Romania in 1857, since then oil has been playing a crucial role in the global economy. •High oil prices can slow economic growth, cause inflationary pressures and create global imbalances. •High oil prices and tight market conditions have also raised fears about oil scarcity and concerns about energy security in many oil- importing countries. •The supply-demand factor seems to be popular among the factors that outweigh the impact of Organization of Petroleum Exporting Countries (OPEC)
Current-induced reversal in magnetic nanopillars passivated by silicon
We demonstrate that magnetic multilayer nanopillars can be efficiently
protected from oxidation by coating with silicon. Both the protected and the
oxidized nanopillars exhibit an increase of reversal current at cryogenic
temperatures. However the magnetic excitation onset current increases only in
the oxidized samples. We show that oxidized nanopillars exhibit anomalous
switching statistics at low temperature, providing a simple test for the
quality of magnetic nanodevices.Comment: 3 pages, 4 figure
On blowup for Yang-Mills fields
We study development of singularities for the spherically symmetric
Yang-Mills equations in dimensional Minkowski spacetime for (the
critical dimension) and (the lowest supercritical dimension). Using
combined numerical and analytical methods we show in both cases that generic
solutions starting with sufficiently large initial data blow up in finite time.
The mechanism of singularity formation depends on the dimension: in the
blowup is exactly self-similar while in the blowup is only approximately
self-similar and can be viewed as the adiabatic shrinking of the marginally
stable static solution. The threshold for blowup and the connection with
critical phenomena in the gravitational collapse (which motivated this
research) are also briefly discussed.Comment: 4 pages, 3 figures, submitted to Physical Review Letter
Integrals of motion and the shape of the attractor for the Lorenz model
In this paper, we consider three-dimensional dynamical systems, as for
example the Lorenz model. For these systems, we introduce a method for
obtaining families of two-dimensional surfaces such that trajectories cross
each surface of the family in the same direction. For obtaining these surfaces,
we are guided by the integrals of motion that exist for particular values of
the parameters of the system. Nonetheless families of surfaces are obtained for
arbitrary values of these parameters. Only a bounded region of the phase space
is not filled by these surfaces. The global attractor of the system must be
contained in this region. In this way, we obtain information on the shape and
location of the global attractor. These results are more restrictive than
similar bounds that have been recently found by the method of Lyapunov
functions.Comment: 17 pages,12 figures. PACS numbers : 05.45.+b / 02.30.Hq Accepted for
publication in Physics Letters A. e-mails : [email protected] &
[email protected]
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