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Full-Text Articles in Physical Sciences and Mathematics
Further Investigation Of The Time Delay, Magnification Ratios, And Variability In The Gravitational Lens 0218 + 357, A. S. Cohen, J. N. Hewitt, C. B. Moore, Deborah B. Haarsma
Further Investigation Of The Time Delay, Magnification Ratios, And Variability In The Gravitational Lens 0218 + 357, A. S. Cohen, J. N. Hewitt, C. B. Moore, Deborah B. Haarsma
University Faculty Publications and Creative Works
High-precision VLA flux density measurements for the lensed images of 0218 + 357 yield a time delay of 10.1 +1.5-1.6 days (95% confidence). This is consistent with independent measurements carried out at the same epoch by Biggs and colleagues in 1999, lending confidence to the robustness of the time delay measurement. However, since both measurements make use of the same features in the light curves, it is possible that the effects of unmodeled processes, such as scintillation or microlensing, are biasing both time delay measurements in the same way. Our time delay estimates result in confidence intervals that are somewhat …
Faint Radio Sources And Star Formation History, Deborah B. Haarsma, R. B. Partridge, R. A. Windhorst, E. A. Richards
Faint Radio Sources And Star Formation History, Deborah B. Haarsma, R. B. Partridge, R. A. Windhorst, E. A. Richards
University Faculty Publications and Creative Works
The centimeter-wave luminosity of local radio galaxies correlates well with their star formation rate. We extend this correlation to surveys of high-redshift radio sources to estimate the global star formation history. The star formation rate found from radio observations needs no correction for dust obscuration, unlike the values calculated from optical and ultraviolet data. Three deep radio surveys have provided catalogs of sources with nearly complete optical identifications and nearly 60% complete spectroscopic redshifts: the Hubble Deep Field and Flanking Fields at 12h + 62°, the SSA13 field at 13h + 42°, and the V15 field at 14h + 52°. …
Directional Correlation In Direct And Sequential Double Ionization Of Model Atoms, Stanley L. Haan, N. Hoekema, S. Poniatowski, W. C. Liu
Directional Correlation In Direct And Sequential Double Ionization Of Model Atoms, Stanley L. Haan, N. Hoekema, S. Poniatowski, W. C. Liu
University Faculty Publications and Creative Works
We discuss directional dependence in the time development of spatial wavefunctions, which includes jet formation, for two-electron model atoms exposed to intense laser fields. Two competing scenarios for double ionization are evident: (1) both electrons emerge simultaneously from the core region and on the same side of the nucleus, and (2) the electrons detach on opposite sides but not simultaneously. The importance of the electron-electron repulsion contribution to the competing processes is investigated for various laser intensities.
Parallel Computing To Start The Millennium, Joel C. Adams, Chris Nevison, Nan C. Schaller
Parallel Computing To Start The Millennium, Joel C. Adams, Chris Nevison, Nan C. Schaller
University Faculty Publications and Creative Works
The experience of three undergraduate computer science programs offering courses on parallel computing is described. On particular, three different solutions to the problem of equipping a lab are discussed. It is shown these solutions may affect the content of the course.
On Simplicial Commutative Algebras With Vanishing André-Quillen Homology, James M. Turner
On Simplicial Commutative Algebras With Vanishing André-Quillen Homology, James M. Turner
University Faculty Publications and Creative Works
In this paper, we study the André-Quillen homology of simplicial commutative ℓ-algebras, ℓ a field, having certain vanishing properties. When ℓ has non-zero characteristic, we obtain an algebraic version of a theorem of J.-P. Serre and Y. Umeda that characterizes such simplicial algebras having bounded homotopy groups. We further discuss how this theorem fails in the rational case and, as an application, indicate how the algebraic Serre theorem can be used to resolve a conjecture of D. Quillen for algebras of finite type over Noetherian rings, having non-zero characteristic.