The integral constraint on convective overshooting (Roxburgh 1976, 1978, 1989) is re-derived for for statistically stationary two-dimensional convection between stress-free horizontal boundaries maintained at constant temperatures, the vertical boundaries being periodic. We report on numerical simulations of such two-dimensional compressible convection in a fluid where the central regions are convectively unstable and the surrounding layers are stable. The results support the conclusion by Roxburgh (1989) that the contribution from the radiative flux is well approximated by the flux carried by the mean temperature gradient, but demonstrate that viscous dissipation is important, reducing the extent of overshooting.

The Executive Committee Working Group on “Cosmic Light” was created in 2014 (at its EC94 Meeting, Apr.30-May 2, Canberra, Australia), in preparation of the contribution of the IAU to the UNESCO “2015 International Year of Light and Light Technologies” (IYL2015), which had been approved by the UN in December 2013 (see http://www.light2015.org/Home.html).

Fossils of Columbian mammoths (Mammuthus columbi) and pygmy mammoths (Mammuthus exilis) have been reported from Channel Islands National Park, California. Most date to the last glacial period (Marine Isotope Stage [MIS] 2), but a tusk of M. exilis (or immature M. columbi) was found in the lowest marine terrace of Santa Rosa Island. Uranium-series dating of corals yielded ages from 83.8 ± 0.6 ka to 78.6 ± 0.5 ka, correlating the terrace with MIS 5.1, a time of relatively high sea level. Mammoths likely immigrated to the islands by swimming during the glacial periods MIS 6 (~ 150 ka) or MIS 8 (~ 250 ka), when sea level was low and the island–mainland distance was minimal, as during MIS 2. Earliest mammoth immigration to the islands likely occurred late enough in the Quaternary that uplift of the islands and the mainland decreased the swimming distance to a range that could be accomplished by mammoths. Results challenge the hypothesis that climate change, vegetation change, and decreased land area from sea-level rise were the causes of mammoth extinction at the Pleistocene/Holocene boundary on the Channel Islands. Pre-MIS 2 mammoth populations would have experienced similar or even more dramatic changes at the MIS 6/5.5 transition.

Curaçao has reef terraces with the potential to provide sea-level histories of interglacial periods. Ages of the Hato (upper) unit of the “Lower Terrace” indicate that this reef dates to the last interglacial period, Marine Isotope Stage (MIS) 5.5. On Curaçao, this high sea stand lasted at least 8000 yr (~ 126 to ~ 118 ka). Elevations and age of this reef show that late Quaternary uplift rates on Curaçao are low, 0.026–0.054 m/ka, consistent with its tectonic setting. Ages of ~ 200 ka for corals from the older Cortalein unit of the Lower Terrace correlate this reef to MIS 7, with paleo-sea level estimates ranging from − 3.3 m to + 2.3 m. The estimates are in agreement with those for MIS 7 made from other localities and indicate that the penultimate interglacial period was a time of significant warmth, on a par with the present interglacial period. The ~ 400 ka (MIS 11) Middle Terrace I on Curaçao, dated by others, may have formed from a paleo-sea level of + 8.3 to + 10.0 m, or (less likely) + 17 m to + 20 m. The lower estimates are conservative compared to previous studies, but still require major ice sheet loss from Greenland and Antarctica.

The stability of rcactively sputtered TiN films on InP for application as a diffusion barrier has been examined using electrical measurements, Auger profiling and scanning electron microscopy (SEM). The samples were subjected to rapid-thermal-annealing (RTA) in a N2 atmosphere at temperatures between 400°C and 900°C. The SEM pictures of “as deposited” and RTA stoichiometric films show that the morphology is smooth, fine-grained and stable until 800°C. Auger depth profiling shows little interdiffusion between TiN and InP for RTA below 800°C. Annealing at temperatures of about 700°C reduces the sheet resistance of TiN relative to the “as-deposited” films by about 50%. Annealing at temperatures above 800°C results in a large sheet resistance. This may be associated with the deterioration of the TiN/InP morphology at high anneal temperatures as observed by SEM.

WNX thin films were deposited at room temperature on (100) n-type GaAs substrates by rf reactive sputtering of a high purity W target in Ar/N2 gas mixtures. Deposition parameters such as the rf power, the ratio of gas flows, and the total pressure can be optimized for the preparation of uniform and low resistivity WNX thin films. The W:N ratio in the as-deposited WNX films was determined using Auger spectroscopy and the morphology was examined by scanning electron microscopy (SEM).

The WNx/GaAs samples were subjected to rapid thermal annealing in an N2 atmosphere at temperatures between 400°C and 800°C. The thermal stability of these structures was examined using electrical measurements and Auger profiling . The results are correlated with the properties of as-deposited films and the influence of various processing parameters will be discussed.

My aim in this essay is to explore the nature and force of “original-acquisition” justifications of private property. By “original-acquisition” justifications, I mean those arguments which purport to establish or importantly contribute to the moral defense of private property by: (a) offering a moral/historical account of how legitimate private property rights for persons first arose (i.e., at a time prior to which no such rights existed); (b) offering a hypothetical or conjectural account of how justified private property could arise (or have arisen) from a propertyless condition; or (c) simply defending an account of how an individual can (or did) make private property in some previously unowned thing (where “things” might include not only land, natural resources, and artifacts, but also, e.g., ideas or other individuals). The “original acquisition” to which such justifications centrally refer, then, may be either the first instance(s) of legitimate private property in human history (typically assumed to have been many centuries ago on earth), or only the first legitimate acquisition of some particular thing (which might, for instance, have occurred yesterday or occur in the future on Mars). But in either case, the justification will involve or entail the defense of one or more moral principles specifying how unowned (or collectively owned) things can become privately owned — that is, the defense of the kind of principles Robert Nozick has called “principles of justice in acquisition.”

The ability to repress P-element-induced gonadal dysgenesis was studied in 14 wild-type strains of D. melanogaster derived from populations in the central and eastern United States. Females from each of these strains had a high ability to repress gonadal dysgenesis in their daughters. Reciprocal hybrids produced by crossing each of the wild-type strains with an M strain demonstrated that repression ability was determined by a complex mixture of chromosomal and cytoplasmic factors. Cytoplasmic transmission of repression ability was observed in all 14 strains and chromosomal transmission was observed in 12 of them. Genomic Southern blots indicated that four of the strains possessed a particular type of P element, called KP, which has been proposed to account for the chromosomal transmission of repression ability. However, in this study several of the strains that lacked KP elements exhibited as much chromosomal transmission of repression ability as the strains that had KP elements, suggesting that other kinds of P elements may be involved.