Search results for "Cosmology and Extragalactic Astrophysics"
showing 10 items of 1668 documents
The Star Height One Problem for Irreducible Automata
1993
The star height of a regular expression is, informally, the maximum number of nested stars in the expression. The star height of a regular language is the minimal star height of a regular expression denoting this language. The notion of star height indicates in a certain sense the “loop complexity” of a regular expression and thus it gives a measure of the complexity of a regular language.
Objective assessment of the effect of pupil size upon the power distribution of multifocal contact lenses
2017
AIM: To analytically assess the effect of pupil size upon the refractive power distributions of different designs of multifocal contact lenses. METHODS: Two multifocal contact lenses of center-near design and one multifocal contact lens of center-distance design were used in this study. Their power profiles were measured using the NIMO TR1504 device (LAMBDA-X, Belgium). Based on their power profiles, the power distribution was assessed as a function of pupil size. For the high addition lenses, the resulting refractive power as a function of viewing distance (far, intermediate, and near) and pupil size was also analyzed. RESULTS: The power distribution of the lenses was affected by pupil siz…
Drift Time Measurement in the ATLAS Liquid Argon Electromagnetic Calorimeter using Cosmic Muons
2010
The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the second layer of the calorimeter are uniform at the level of 1.3% in the barrel and 2.8% in the endcaps. This leads to an estimated contribution to the constant term of (0.29-0.04+0.05)% in the barrel and (0.54-0.04+0.06)% in the endcaps. The same data are used to measure the drift velocity of ionization electrons …
Spectroscopic properties of pure and Coumarin 153-doped thin films of sol-gel silica xerogels
1999
Abstract Thin-films doped with Coumarin 153, an important laser dye, have been prepared by the sol-gel method. Spectroscopic properties of the entrapped dye are studied by electronic absorption, diffuse reflectance, electronic excitation, emission and time-resolved emission techniques. The obtained results indicate that the entrapment of the dye results in formation of molecular aggregates having absorption and emission characteristics different from those of the monomeric dye. The blue matrix emission band (at approx. 450 nm) is relatively short-lived while the red band (at approx. 700 nm) displays a very long lifetime. Electronic excitation spectra of the sol-gel thin-films suggest that t…
"Table 1" of "Measurements of the line shape of the Z0 and determination of electroweak parameters from its hadronic and leptonic decays"
1994
Hadronic cross sections from the 1990 data set. Additional systematic uncertainties come from efficiencies and background of 0.4 pct in addition to the luminosity uncertainty 0.7 pct.
"Table 40" of "Tuning and test of fragmentation models based on identified particles and precision event shape data."
1996
Compilation of multiplicities of baryons from current LEP I data.
"Table 10" of "Cross-sections and leptonic forward-backward asymmetries from the Z0 running of LEP."
2000
Cross section and forward-backward asymmetry in the TAU+ TAU- channel for the 1993 data. Additional systematic error for cross section of 0.60 PCT (efficiencies and backgrounds) and 0.29 PCT (absolute luminosity). Additional systematic error for the asymmetry of 0.0020.
IPHAS-selected classical Be stars
2016
We present a semi-automatic procedure to obtain fundamental physical parameters and distances of classical Be (CBe) stars, based on the Barbier-Chalonge-Divan (BCD) spectrophotometric system. Our aim is to apply this procedure to a large sample of CBe stars detected by the IPHAS photometric survey, to determine their fundamental physical parameters and to explore their suitability as galactic structure tracers. In this paper we describe the methodology used and the validation of the procedure by comparing our results with those obtained from different independent astrophysical techniques for subsamples of stars in common with other studies. We also present a test case study of the galactic …
Be stars in the exofield of CoRoT. II.
2018
The class of Be stars are the epitome of rapid rotators in the main sequence. These stars are privileged candidates for studying the incidence of rotation on the stellar internal structure and on non-radial pulsations. Pulsations are considered possible mechanisms to trigger mass-ejection phenomena required to build up the circumstellar disks of Be stars. Time series analyses of the light curves of 15 faint Be stars observed with the CoRoT satellite were performed to obtain the distribution of non-radial pulsation (NRP) frequencies in their power spectra at epochs with and without light outbursts and to discriminate pulsations from rotation-related photometric variations. Standard Fourier t…
Non-thermal processes in coronae and beyond
2012
This contribution summarizes the splinter session "Non-thermal processes in coronae and beyond" held at the Cool Stars 17 workshop in Barcelona in 2012. It covers new developments in high energy non-thermal effects in the Earth's exosphere, solar and stellar flares, the diffuse emission in star forming regions and reviews the state and the challenges of the underlying atomic databases.