Atomic data for neutron-capture elements III. Charge transfer rate coefficients for low-charge ions of Ge, Se, Br, Kr, Rb, and Xe

We present total and final-state resolved charge transfer (CT) rate coefficients for low-charge Ge, Se, Br, Kr, Rb, and Xe ions reacting with neutral hydrogen over the temperature range 10^2--10^6 K. Each of these elements has been detected in ionized astrophysical nebulae, particularly planetary nebulae. CT rate coefficients are a key ingredient for the ionization equilibrium solutions needed to determine total elemental abundances from those of the observed ions. A multi-channel Landau Zener approach was used to compute rate coefficients for projectile ions with charges q=2-5, and for singly-charged ions the Demkov approximation was utilized. Our results for five-times ionized species are lower limits, due to the incompleteness of level energies in the NIST database. In addition, we computed rate coefficients for charge transfer ionization reactions between the neutral species of the above six elements and ionized hydrogen. The resulting total and state-resolved CT rate coefficients are tabulated and available at the CDS. In tandem with our concurrent investigations of other important atomic processes in photoionized nebulae, this work will enable robust investigations of neutron-capture element abundances and nucleosynthesis via nebular spectroscopy.Comment: 11 pages, 4 figures, accepted for publication in Astronomy & Astrophysic

VCU Professor Researches Early Intervention Programs for Preschools, Ties to RTR Program

The Institute for Education Sciences, IES, a branch of the US Department of Education, awarded a grant to VCU professors Bryce McLeod, Ph.D and Kevin Sutherland, Ph.D to research behavioral problems in local preschool children. The four-year grant totaled up to $1.6 million

Alfred Henry Sturtevant (November 21, 1891-April 6, 1970)

It would be difficult to overestimate the importance of Sturtevant's scientific contributions to the development of present-day genetic concepts. Even so I am reluctant to attempt any such evaluation. Memories of a warm personal relationship extending over nearly fifty years distract me from strict objectivity. In any case, at the time (1913) of Sturtevant's earliest and perhaps most fundamental discovery (1) I was too young to appreciate its impact on contemporary biological thought. I doubt that a valid estimation of the worth of a particular contribution can be had without an understanding of the state of knowledge and interpretations generally held by scientists at the time. I do, however, vividly recall the extreme skepticism with which many biologists viewed genetic interpretations five, or even ten, years later, and I suspect that not all who accepted Mendelian interpretations could appreciate the importance of Sturtevant's deductions. It is fortunate for us that Sturtevant's penchant for accurate reporting overcame his innate modesty sufficiently to give something of his own assessment of the relation of his work to the particular time-in "A History of Genetics" (2), especially in the chapter titled "The Fly Room" which has been separately issued (3). It is also fortunate that a number of his most noteworthy publications were reissued in a single volume in commemoration of his seventieth birthday (4). As pointed out by a number of reviewers of this volume, some of whom were Sturtevant's contemporaries, it is remarkable that a single individual should have made so many fundamental contributions

Who was Jesus?

Reviewed Book: Wright, November T. (Nicholas Thomas), Bp. Who was Jesus?. Grand Rapids: Eerdmans; London: SPCK, 1992

Immortal Mortals

Junior Information Systems and Bioinformatics major Michael Kiflezghi focuses his research interests on an organism’s lifespan and gut microbial communities