15,303 research outputs found
A digitalized solar ultraviolet spectrum
Digitalized solar ultraviolet spectrum obtained in rocket experiments for use in analysis of upper atmosphere experiment
Model for Cumulative Solar Heavy Ion Energy and Linear Energy Transfer Spectra
A probabilistic model of cumulative solar heavy ion energy and LET spectra is developed for spacecraft design applications. Spectra are given as a function of confidence level, mission time period during solar maximum and shielding thickness. It is shown that long-term solar heavy ion fluxes exceed galactic cosmic ray fluxes during solar maximum for shielding levels of interest. Cumulative solar heavy ion fluences should therefore be accounted for in single event effects rate calculations and in the planning of space missions
High-resolution observation of the Venus dayglow spectrum 1250-1430 angstroms
The spectrum of the dayglow of Venus between 1250 and 1430 A was measured in high resolution with the International Ultraviolet Explorer. Seven exposures which were made with the short wavelength camera in the high dispersion mode using the large aperture were combined to give a total exposure time of 309 min. The atomic oxygen lines at 1302.2, 1304.9, 1306.0, and 1355.6 A are present. In addition, the (14,3) and (14,4) bands of the carbon monoxide fourth positive system at 1317 and 1354 A respectively are identified. These bands are compared with synthetic spectra, showing the excitation mechanism to be fluorescent scattering of solar Lyman alpha radiation
Seasonal observation of Mars
The International Ultraviolet Explorer detected the Hartley bands of ozone in the spectrum of Mars. Seasonal observations show a variation in the north consistent with the measurement of Mariner 9. Observations during Martian late fall in the south were also made
Electric field response of strongly correlated one-dimensional metals: a Bethe-Ansatz density functional theory study
We present a theoretical study on the response properties to an external
electric field of strongly correlated one-dimensional metals. Our investigation
is based on the recently developed Bethe-Ansatz local density approximation
(BALDA) to the density functional theory formulation of the Hubbard model. This
is capable of describing both Luttinger liquid and Mott-insulator correlations.
The BALDA calculated values for the static linear polarizability are compared
with those obtained by numerically accurate methods, such as exact (Lanczos)
diagonalization and the density matrix renormalization group, over a broad
range of parameters. In general BALDA linear polarizabilities are in good
agreement with the exact results. The response of the exact exchange and
correlation potential is found to point in the same direction of the perturbing
potential. This is well reproduced by the BALDA approach, although the fine
details depend on the specific parameterization for the local approximation.
Finally we provide a numerical proof for the non-locality of the exact exchange
and correlation functional.Comment: 8 pages and 8 figure
Dispersion and connectivity estimates along the U.S. west coast from a realistic numerical model
Near-surface particle dispersion, larval dispersal and connectivity along the U.S west coast were explored using a realistic numerical model of the California Current System. Seasonal model velocities were qualitatively and quantitatively evaluated using Global Drifter Program data. The model displayed a clear seasonal cycle of eddy energy near the coast with energy maxima southwest of major headlands. Eddy speeds were correlated with drifter-based estimates during summer and fall when compared spatially. Over six million passive, Lagrangian particles were released in the upper 20 m of the water column within 10 km of the California and Oregon coasts and tracked for 7 years. The effect of subgridscale vertical turbulence was parameterized with a random walk model. Resulting trajectories yielded climatological maps of particle dispersion. Particle densities varied with release region, release season and time-since-release. Dispersal distances and coastal connectivity varied with season of release, release location, release depth and pelagic larval duration (PLD). Connectivity was clearly influenced by major geographic features such as the Gulf of the Farallones and Cape Mendocino. Given a moderate (30–60 day) PLD, mean dispersal distances varied from ∼10–230 km, with standard deviations of ∼130–220 km. For release locations from Palos Verdes to Point Sur, the primary direction of dispersal was northward for a moderate PLD, regardless of season. For long PLDs (120–180 day), mean dispersal distances were larger (∼40–440 km), with standard deviations of ∼330–540 km. In winter given a long PLD, dispersal was primarily southward for release locations north of Point Arena. Increasing release depths to 40–60 m altered mean dispersal distances by 50–250 km polewards, but had little effect on standard deviations. Point Conception did not act as a barrier to dispersal for source regions in the Southern California Bight
Composition Conditions for Classes of Analytic Functions
We prove that for classes of analytic functions tree composition condition
and composition condition coincide.Comment: 13 page
Raman signatures of classical and quantum phases in coupled dots: A theoretical prediction
We study electron molecules in realistic vertically coupled quantum dots in a
strong magnetic field. Computing the energy spectrum, pair correlation
functions, and dynamical form factor as a function of inter-dot coupling via
diagonalization of the many-body Hamiltonian, we identify structural
transitions between different phases, some of which do not have a classical
counterpart. The calculated Raman cross section shows how such phases can be
experimentally singled out.Comment: 9 pages, 2 postscript figures, 1 colour postscript figure, Latex 2e,
Europhysics Letters style and epsfig macros. Submitted to Europhysics Letter
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