5,062 research outputs found
QED structure function of the photon at LEP
We report about the studies of the processes e/sup +/e/sup -/ to e /sup +/e/sup -/e/sup +/e/sup -/ and e/sup +/e/sup -/ to e/sup +/e/sup -/ mu /sup +/ mu /sup -/ in a single tag configuration, using data collected by the LEP experiments at square root S approximately=91 Ge V. (9 refs)
The role of the charge state of PAHs in ultraviolet extinction
Aims: We explore the relation between charge state of polycyclic aromatic
hydrocarbons (PAHs) and extinction curve morphology. Methods: We fit extinction
curves with a dust model including core-mantle spherical particles of mixed
chemical composition (silicate core, and carbonaceous layers),
and an additional molecular component. We use exact methods to calculate the
extinction due to classical particles and accurate computed absorption spectra
of PAHs in different charge states, for the contribution due to the molecular
component, along a sample of five rather different lines of sight. Results: A
combination of classical dust particles and mixtures of real PAHs
satisfactorily matches the observed interstellar extinction curves. Variations
of the spectral properties of PAHs in different charge states produce changes
consistent with the varying relative strengths of the bump and non-linear
far-UV rise.Comment: 5 pages, 3 figures, Astronomy & Astrophysics Letters, in pres
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NWA 4415 AND 4416: Two new enstatite chondrites from northwest Africa
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Textural and compositional features of NWA 4222, A new Martian meteorite
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