Vertex-Unfoldings of Simplicial Polyhedra

We present two algorithms for unfolding the surface of any polyhedron, all of whose faces are triangles, to a nonoverlapping, connected planar layout. The surface is cut only along polyhedron edges. The layout is connected, but it may have a disconnected interior: the triangles are connected at vertices, but not necessarily joined along edges.Comment: 10 pages; 7 figures; 8 reference

Winners and Losers: Formula versus Competitive Funding of Agricultural Research

Research and Development/Tech Change/Emerging Technologies, O3, O4, Q16,

ECONOMIC ANALYSIS OF ENVIRONMENTAL BENEFITS OF INTEGRATED PEST MANAGEMENT

Public support for integrated pest management (IPM) is derived in part from concerns over food safety and the environment, yet few studies have assessed the economic value of health and environmental benefits of IPM. An approach is suggested for such an assessment and applied to the Virginia peanut IPM program. Effects of IPM on environmental risks posed by pesticides are assessed and society's willingness to pay to reduce those risks is estimated. The annual environmental benefits of the peanut IPM program are estimated at $844,000. The estimates of pesticide risks and willingness to pay can be applied elsewhere in economic assessments of IPM.Integrated pest management, Willingness to pay, Environmental benefits, Crop Production/Industries, Environmental Economics and Policy,

ESTIMATING RETURNS TO AGRICULTURAL RESEARCH, EXTENSION, AND TEACHING AT THE STATE LEVEL

The majority of decisions concerning investment and allocation of public funds for agricultural research, extension, and teaching (RET) are made at the state-level, while most of the quantitative RET evaluations are made on a national basis. This paper illustrates an approach for conducting a disaggregated state-level evaluation of agricultural research, extension, and teaching. Ridge regression is employed to handle multicollinearity problems.Teaching/Communication/Extension/Profession,

Extrasolar Planets in the Classroom

The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique. Following the simple analysis procedure describe we are able to determine the planetary radius to be 1.27 +/- 0.20 R_{J} which, within errors agrees with the establish value of 1.32 +/- 0.25 R_{J}.Comment: 7 pages, 2 figures, published in Physics Educatio

Discovery of excess O I absorption towards the z = 6.42 QSO SDSS J1148+5251

We present a search for O I in the spectra of nine 4.9 < z_qso < 6.4 QSOs taken with Keck/HIRES. We detect six systems with N(O I) > 10^13.7 cm^{-2} in the redshift intervals where O I 1302 falls redward of the Ly-alpha forest. Four of these lie towards SDSS J1148+5251 (z_qso = 6.42). This imbalance is unlikely to arise from variations in sensitivity among our data or from a statistical fluctuation. The excess O I occurs over a redshift interval that also contains transmission in Ly-alpha and Ly-beta. Therefore, if these O I systems represent pockets of neutral gas, then they must occur within or near regions of the IGM that are highly ionized. In contrast, no O I is detected towards SDSS J1030+0524 (z_qso = 6.30), whose spectrum shows complete absorption in Ly-alpha and Ly-beta over \Delta z ~ 0.2. Assuming no ionization corrections, we measure mean abundance ratios = -0.04 +/- 0.06, = -0.31 +/- 0.09, and = -0.34 +/- 0.07 (2 sigma), which are consistent with enrichment dominated by Type II supernovae. The O/Si ratio limits the fraction of silicon in these systems contributed by metal-free very massive stars to < 30%, a result which is insensitive to ionization corrections. The ionic comoving mass densities along the z_qso > 6.2 sightlines, including only the detected systems, are \Omega(O I) = (7.0 +/- 0.6) * 10^{-8}, \Omega(Si II) = (9.6 +/- 0.9) * 10^{-9}, and \Omega(C II) = (1.5 +/- 0.2) * 10^{-8}.Comment: Submitted to ApJ, with changes to reflect referee's comment

Activation mechanisms in sodium-doped Silicon MOSFETs

We have studied the temperature dependence of the conductivity of a silicon MOSFET containing sodium ions in the oxide above 20 K. We find the impurity band resulting from the presence of charges at the silicon-oxide interface is split into a lower and an upper band. We have observed activation of electrons from the upper band to the conduction band edge as well as from the lower to the upper band. A possible explanation implying the presence of Hubbard bands is given.Comment: published in J. Phys. : Condens. Matte

SHORTFALLS IN 1997 NET FARM INCOME IN NORTH DAKOTA (Prepared for Senators Byron Dorgan and Kent Conrad)

North Dakota net farm income declined in 1997 due to adverse weather conditions and low prices. The total income loss in 1997 was estimated to be $394 million, which was divided into$290 million due to weather and diseases, and $104 million due to lower-than-average prices. Net farm income losses were largest in Region 3 (Northeast), followed by Regions 1 (Northwest) and 6 (East Central). HRS wheat accounted for the largest income loss, followed by durum and barley.Net farm income, crop losses, weather conditions, North Dakota input output model, Agricultural Finance,