50,620 research outputs found
System identification and pattern recognition
New method for system identification based on relaxation technique used in pattern recognitio
Spectroscopic reassignment and ground state dissociation energy of molecular iodine
Spectroscopic reassignment and ground state dissociation energy of molecular iodin
Permeability of a one-dimensional potential barrier
Permeability of one dimensional potential barrie
Sensitivity design technique for optimal control, part C Final report
Optimal sensitivity design techniques to design feedback control system for large, flexible booste
Slow X-ray bursts and chromospheric flares with filament disruption
The data from OGO-5 and OSO-7 X-ray experiments have been analyzed to study six chromospheric flares with filament disruption associated with slow thermal X-ray bursts. Filament activation accompanied by a slight X-ray enhancement precedes the first evidence of H alpha flare by a few minutes. Rapid increase of the soft X-ray flux is accompanied by a sudden brightening of the filament when viewed on-band H alpha. Thereafter the bright chromospheric strands reach their maximum brightness with maximum X-ray flux. Any plateau or slow decay phase in the X-ray flux is accompanied by a quieting in filament activity and even by filament re-appearance. The height of the disrupted prominence is proportional to the soft X-ray flux for the August 3, 1970 limb occulted event
A continuous low star formation rate in IZw 18 ?
Deep long-slit spectroscopic observations of the blue compact galaxy IZw 18
obtained with the CFH 3.6 m Telescope are presented. The very low value of
oxygen abundance previously reported is confirmed and a very homogeneous
abundance distribution is found (no variation larger than 0.05 dex) over the
whole ionized region. We concur with Tenorio-Tagle (1996) and Devost et al.
(1997) that the observed abundance level cannot result from the material
ejected by the stars formed in the current burst, and propose that the observed
metals were formed in a previous star formation episode. Metals ejected in the
current burst of star formation remain most probably hidden in a hot phase and
are undetectable using optical spectroscopy. We discuss different scenarios of
star formation in IZw 18. Combining various observational facts, for instance
the faint star formation rate observed in low surface brightness galaxies van
Zee et al. (1997), it is proposed that a low and continuous rate of star
formation occurring during quiescent phases between bursts could be a
significant source of metal enrichment of the interstellar medium.Comment: 10 pages, 4 Postscript figures, to be published in Astronomy and
Astrophysics main journa
Dissociation energy and long-range potential of diatomic molecules from vibrational spacings - The halogens
Dissociation energy and long-range potential of diatomic molecules from vibrational spacings, halogen
The pion-pion scattering amplitude. III: Improving the analysis with forward dispersion relations and Roy equations
We complete and improve the fits to experimental scattering
amplitudes, both at low and high energies, that we performed in the previous
papers of this series. We then verify that the corresponding amplitudes satisfy
analyticity requirements, in the form of partial wave analyticity at low
energies, forward dispersion relations (FDR) at all energies, and Roy equations
below threshold; the first by construction, the last two, inside
experimental errors. Then we repeat the fits including as constraints FDR and
Roy equations. The ensuing central values of the various scattering amplitudes
verify very accurately FDR and, especially, Roy equations, and change very
little from what we found by just fitting data, with the exception of the D2
wave phase shift, for which one parameter moves by . These improved
parametrizations therefore provide a reliable representation of pion-pion
amplitudes with which one can test various physical relations. We also present
a list of low energy parameters and other observables. In particular, we find
,
and .Comment: Plain TeX. 29 figures. Version to be published in PRD, with improved
P and F wave
Shape resonances and rotationally predissociating levels - The atomic collision time delay functions and quasibound level properties of H2 /Chi /1 Sigma g plus//
Atomic collision time delay functions and quasibound level properties of ground state of molecular hydroge
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