Performance of a spin-based insulated gate field effect transistor

Fundamental physical properties limiting the performance of spin field effect transistors are compared to those of ordinary (charge-based) field effect transistors. Instead of raising and lowering a barrier to current flow these spin transistors use static spin-selective barriers and gate control of spin relaxation. The different origins of transistor action lead to distinct size dependences of the power dissipation in these transistors and permit sufficiently small spin-based transistors to surpass the performance of charge-based transistors at room temperature or above. This includes lower threshold voltages, smaller gate capacitances, reduced gate switching energies and smaller source-drain leakage currents.Comment: 4 pages including 3 figures, APL in pres

Artificial Intelligence

Contains research objectives and reports on eight research projects.Computation Center, M.I.T

Bromoform and dibromomethane above the Mauritanian upwelling: Atmospheric distributions and oceanic emissions

Natural sources of bromoform (CHBr3) and dibromomethane (CH2Br2), including oceanic emissions, contribute to stratospheric and tropospheric O3 depletion. Convective transport over tropical oceans could deliver large amounts of these short-lived organic bromine species to the upper atmosphere. High mixing ratios of atmospheric CHBr3 in air masses from the northwest African coast have been hypothesized to originate from the biologically active Mauritanian upwelling. During a cruise into the upwelling source region in spring 2005 the atmospheric mixing ratios of the brominated compounds CHBr3 and CH2Br2 were found to be elevated above the marine background and comparable to measurements in other coastal regions. The shelf waters were identified as a source of both compounds for the atmosphere. The calculated sea-to-air emissions support the hypothesis of a strong upwelling source for reactive organic bromine. However, calculated emissions were not sufficient to explain the elevated concentrations observed in the coastal atmosphere. Other strong sources that could contribute to the large atmospheric mixing ratios previously observed over the Atlantic Ocean must exist within or near West Africa

1928 Ruby Yearbook

A digitized copy of the 1928 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1030/thumbnail.jp

1981 Ruby Yearbook

A digitized copy of the 1981 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1084/thumbnail.jp

How and when plume zonation appeared during the 132 Myr evolution of the Tristan Hotspot

Increasingly, spatial geochemical zonation, present as geographically distinct, subparallel trends, is observed along hotspot tracks, such as Hawaii and the Galapagos. The origin of this zonation is currently unclear. Recently zonation was found along the last B70 Myr of the Tristan-Gough hotspot track. Here we present new Sr–Nd–Pb–Hf isotope data from the older parts of this hotspot track (Walvis Ridge and Rio Grande Rise) and re-evaluate published data from the Etendeka and Parana flood basalts erupted at the initiation of the hotspot track. We show that only the enriched Gough, but not the less-enriched Tristan, component is present in the earlier (70–132 Ma) history of the hotspot. Here we present a model that can explain the temporal evolution and origin of plume zonation for both the Tristan-Gough and Hawaiian hotspots, two end member types of zoned plumes, through processes taking place in the plume sources at the base of the lower mantle

Regional-scale brine migration along vertical pathways due to CO2 injection - Part 1: The participatory modeling approach

Saltwater intrusion into potential drinking water aquifers due to the injection of CO₂ into deep saline aquifers is one of the potential hazards associated with the geological storage of CO₂. Thus, in a site selection process, models for predicting the fate of the displaced brine are required, for example, for a risk assessment or the optimization of pressure management concepts. From the very beginning, this research on brine migration aimed at involving expert and stakeholder knowledge and assessment in simulating the impacts of injecting CO₂ into deep saline aquifers by means of a participatory modeling process. The involvement exercise made use of two approaches. First, guideline-based interviews were carried out, aiming at eliciting expert and stakeholder knowledge and assessments of geological structures and mechanisms affecting CO₂-induced brine migration. Second, a stakeholder workshop including the World Café format yielded evaluations and judgments of the numerical modeling approach, scenario selection, and preliminary simulation results. The participatory modeling approach gained several results covering brine migration in general, the geological model sketch, scenario development, and the review of the preliminary simulation results. These results were included in revised versions of both the geological model and the numerical model, helping to improve the analysis of regional-scale brine migration along vertical pathways due to CO₂ injection

1958 Ruby Yearbook

A digitized copy of the 1958 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1061/thumbnail.jp

1960 Ruby Yearbook

A digitized copy of the 1960 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1063/thumbnail.jp

1970 Ruby Yearbook

A digitized copy of the 1970 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1073/thumbnail.jp