SUSTAINABLE DEVELOPMENT IN MINERAL ECONOMIES: THE EXAMPLE OF BOTSWANA

Environmental Economics and Policy, Resource /Energy Economics and Policy,

Kinetics of the Electrical Discharge Pumped Oxygen-iodine Laser

A systematic study of microwave discharges at 2.45 GHz has been performed through the pressure range of sustainable electric discharges in pure oxygen flows of 2 to 10 Torr. A corresponding study of 13.56 MHz has also been performed at pressures of 2, 4, and 7 Torr. Optical emissions from O2(a 1Δ), O2(b 1Σ), and O-atoms have been measured from the center of a μ-wave discharge. Discharge residence times from 0.1 to 5 ms have been reported. The O2(b 1Σ) emissions, with a spectral resolution of 0.01 nm, have been used to measure the temperature of the gas, which typically reaches a steady-state of 1,200 K. The interpretation of the measured O2(a 1Δ), yield, using a streamlined, nearly analytic model, cast new light on the kinetics within the electric discharge. The pseudo-first order quenching rate of O2(a 1Δ) ranges from 6,000 s-1 for μ-wave discharges to 600 s-1 for radio frequency (RF) discharges, independent of gas pressure and flow rate. The observations are consistent with a second order reaction channel that is dependent on both the electron and oxygen ground state concentrations. The role of vibrationally excited ground state oxygen is explored and provides a plausible destruction mechanism

Collaborating with Academic Affairs to Cultivate Environments that Support Student Integrity

Integrity development has been recognized as a common outcome at many colleges and universities (Association of American Colleges & Universities, 2012; Chickering & Reisser, 1993; Dugan & Komives, 2007; Higher Education Research Institute, 1996). Thus, it is important to create academic and student affairs collaborations that promote the development of students’ integrity and values clarification. In this article, we briefly discuss existing and new integrity research that informs how practitioners and administrators can structure environments supportive of students’ value clarification and congruence with their actions on campus. We use student Honor Codes/Codes of Conduct as an example source of collaboration on campus

The Affect of Animal Gender on Fed Cattle Producer Marketing Behavior

Weekly grid market share by volume for slaughter steers is compared to slaughter heifers. Summary statistics indicate average grid market share for steers (42%) is 27% higher than slaughter heifers (33%). The literature indicates that pregnancy and increased dark cutter incidence associated with heifers relative to steers creates additional financial risk when heifers are sold on a grid. Econometric analysis suggests grid market share is less sensitive to change in market conditions for heifers relative to steers. The empirical evidence is consistent with the supposition that marketing heifers is riskier than marketing steers on a grid. Thus sellers need stronger economic incentives to market heifers on a grid relative to steers.grid pricing, fed cattle, animal gender, risk, Livestock Production/Industries, Q00,

High time-resolution observations of the Vela pulsar

We present high time resolution observations of single pulses from the Vela pulsar (PSR B0833-45) made with a baseband recording system at observing frequencies of 660 and 1413 MHz. We have discovered two startling features in the 1413 MHz single pulse data. The first is the presence of giant micro-pulses which are confined to the leading edge of the pulse profile. One of these pulses has a peak flux density in excess of 2500 Jy, more than 40 times the integrated pulse peak. The second new result is the presence of a large amplitude gaussian component on the trailing edge of the pulse profile. This component can exceed the main pulse in intensity but is switched on only relatively rarely. Fluctutation spectra reveal a possible periodicity in this feature of 140 pulse periods. Unlike the rest of the profile, this component has low net polarization and emits predominantly in the orthogonal mode. This feature appears to be unique to the Vela pulsar. We have also detected microstructure in the Vela pulsar for the first time. These same features are present in the 660 MHz data. We suggest that the full width of the Vela pulse profile might be as large as 10 ms but that the conal edges emit only rarely.Comment: 6 pages, 5 figures, In Press with ApJ Letter

Efficient Mesh Management in Firedrake Using PETSc DMPlex

The use of composable abstractions allows the application of new and established algorithms to a wide range of problems, while automatically inheriting the benefits of well-known performance optimizations. This work highlights the composition of the PETSc DMPlex domain topology abstraction with the Firedrake automated finite element system to create a PDE solving environment that combines expressiveness, flexibility, and high performance. We describe how Firedrake utilizes DMPlex to provide the indirection maps required for finite element assembly, while supporting various mesh input formats and runtime domain decomposition. In particular, we describe how DMPlex and its accompanying data structures allow the generic creation of user-defined discretizations, while utilizing data layout optimizations that improve cache coherency and ensure overlapped communication during assembly computation