11,309 research outputs found
Regional significance of volcanic geochemistry in the Far Triple Junction, Ethiopia
Regional significance of volcanic geochemistry in far Triple Junction, Ethiopi
Notes on the Afar triple junction
Geological anomalies of Afar and bordering plateau
Ethiopian rift and plateaus - Some volcanic petrochemical differences
Volcanic petrochemical differences in Ethiopian rift and plateau
Optical Turbulence Measurements and Models for Mount John University Observatory
Site measurements were collected at Mount John University Observatory in 2005
and 2007 using a purpose-built scintillation detection and ranging system.
profiling indicates a weak layer located at 12 - 14 km above sea
level and strong low altitude turbulence extending up to 5 km. During calm
weather conditions, an additional layer was detected at 6 - 8 km above sea
level. profiling suggests that tropopause layer velocities are nominally
12 - 30 m/s, and near-ground velocities range between 2 -- 20 m/s, dependent on
weather. Little seasonal variation was detected in either and
profiles. The average coherence length, , was found to be cm for
the full profile at a wavelength of 589 nm. The average isoplanatic angle,
, was arcsec. The mean turbulence altitude,
, was found to be km above sea level. No average in the
Greenwood frequency, , could be established due to the gaps present in the
\vw\s profiles obtained. A modified Hufnagel-Valley model was developed to
describe the profiles at Mount John, which estimates at 6 cm
and at 0.9 arcsec. A series of models were developed, based
on the Greenwood wind model with an additional peak located at low altitudes.
Using the model and the suggested model for moderate ground
wind speeds, is estimated at 79 Hz.Comment: 14 pages; accepted for publication in PAS
QED self-energy contribution to highly-excited atomic states
We present numerical values for the self-energy shifts predicted by QED
(Quantum Electrodynamics) for hydrogenlike ions (nuclear charge ) with an electron in an , 4 or 5 level with high angular momentum
(). Applications include predictions of precision transition
energies and studies of the outer-shell structure of atoms and ions.Comment: 20 pages, 5 figure
Modification of nuclear transitions in stellar plasma by electronic processes: K-isomers in 176Lu and 180Ta under s-process conditions
The influence of the stellar plasma on the production and destruction of
K-isomers is studied for the examples 176Lu and 180Ta. Individual
electromagnetic transitions are enhanced predominantly by nuclear excitation by
electron capture, whereas the other mechanisms of electron scattering and
nuclear excitation by electron transition give only minor contributions. It is
found that individual transitions can be enhanced significantly for low
transition energies below 100 keV. Transitions with higher energies above 200
keV are practically not affected. Although one low-energy transition in 180Ta
is enhanced by up to a factor of 10, the stellar transition rates from low-K to
high-K states via so-called intermediate states in 176Lu and 180Ta do not
change significantly under s-process conditions. The s-process nucleosynthesis
of 176Lu and 180Ta remains essentially unchanged.Comment: 10 pages, 10 figures, Phys. Rev. C, accepte
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