A Plant Collection from the Wrangell Mountains, Alaska

Lists with brief descriptive and distributional notes, 115 vascular plant taxa collected as part of Arctic Institute of North America High Mountain Environment Project 1966-1967, from the Skolai Creek floodplain at 4800 ft, the steep slopes leading to and from the 5800 ft Chitistone Pass. Some of the species bridge occurrence gaps in populations of central Alaska and St Elias Mts of SW Yukon; some are known from so few localities that their Alaska distribution is uncertain; the remainder are widely distributed in most alpine areas of Alaska and the Yukon. A southern extension of Draba oblongata is noted

Notes on the Alpine Flora of the St. Elias Mountains

Botanical exploration along the continental slope of the northern St. Elias Mountains has revealed several floristic novelties. My 1965 collection from a nunatak in the Kaskawulsh Glacier (60°43'N, 139°19'W) was examined by Dr. Eric Hultén, Museum of Natural History, Stockholm, and he has reported and mapped this new locality for Lewisia pygmaea (Gray) Robins., Arabis lemmonii Wats., and A. lyallii Wats., far north of their previously known range. Neilson collected nearby and also found interesting taxa, in particular the only North American population of the Eurasian species Artemisia rupestris L. Work has continued during subsequent summers (1966-1969) east from the nunatak along the Kaskawulsh Glacier-Slims River drainage, north to the vicinity of the Steele Glacier, and into the northernmost portion of the St. Elias Mountains on the south side of the upper White River valley. [These] ... notes are offered for those botanists with an interest in the floristics of northern regions

Yang-Mills theory for bundle gerbes

Given a bundle gerbe with connection on an oriented Riemannian manifold of dimension at least equal to 3, we formulate and study the associated Yang-Mills equations. When the Riemannian manifold is compact and oriented, we prove the existence of instanton solutions to the equations and also determine the moduli space of instantons, thus giving a complete analysis in this case. We also discuss duality in this context.Comment: Latex2e, 7 pages, some typos corrected, to appear in J. Phys. A: Math. and Ge

Information sciences experiment system

The rapid expansion of remote sensing capability over the last two decades will take another major leap forward with the advent of the Earth Observing System (Eos). An approach is presented that will permit experiments and demonstrations in onboard information extraction. The approach is a non-intrusive, eavesdropping mode in which a small amount of spacecraft real estate is allocated to an onboard computation resource. How such an approach allows the evaluation of advanced technology in the space environment, advanced techniques in information extraction for both Earth science and information science studies, direct to user data products, and real-time response to events, all without affecting other on-board instrumentation is discussed

A modified Oster-Murray-Harris mechanical model of morphogenesis

There are two main modeling paradigms for biological pattern formation in developmental biology: chemical prepattern models and cell aggregation models. This paper focuses on an example of a cell aggregation model, the mechanical model developed by Oster, Murray, and Harris [Development, 78 (1983), pp. 83--125]. We revisit the Oster--Murray--Harris model and find that, due to the infinitesimal displacement assumption made in the original version of this model, there is a restriction on the types of boundary conditions that can be prescribed. We derive a modified form of the model which relaxes the infinitesimal displacement assumption. We analyze the dynamics of this model using linear and multiscale nonlinear analysis and show that it has the same linear behavior as the original Oster--Murray--Harris model. Nonlinear analysis, however, predicts that the modified model will allow for a wider range of parameters where the solution evolves to a bounded steady state. The results from both analyses are verified through numerical simulations of the full nonlinear model in one and two dimensions. The increased range of boundary conditions that are well-posed, as well as a wider range of parameters that yield bounded steady states, renders the modified model more applicable to, and more robust for, comparisons with experiments