The formal expression of pro positional attitudes, especially when nested (iterated), is an important problem for A I . An interesting first-order extensional logical system for such expression has been proposed by Creary. In this system concepts (and concepts of concepts, etc.) are made explicit. The system includes "concept functions", which are special functions which act on and deliver conc...

Introduction: Interest in buried glacial ice has gained considerable attention in recent years due to its potential as an archive for long-term climate change and as a consequence of recent suggestions that call for relatively young, near-surface buried ice on Mars. Geochemical analyses of ice stored in stagnant debriscovered glaciers in the western Dry Valleys region of Antarctica (stable upla...

The structural and compositional stabilities of two-dimensional (2D) Bi2Te3 and Bi2Se3 nanocrystals, produced by both colloidal synthesis and by liquid phase exfoliation, were studied by in situ transmission electron microscopy (TEM) during annealing at temperatures between 350 and 500 °C. The sublimation process induced by annealing is structurally and chemically anisotropic and takes place th...

Fields of pits, both large and small, in Tombaugh Regio (Sputnik Planitia, and the Pitted Uplands to the east), and along the scarp of Piri Rupes, are examples of landscapes on Pluto where we conclude that sublimation drives their formation and evolution. Our heuristic modeling closely mimics the form, spacing, and arrangement of a variety of Tombaugh Regio’s pits. Pluto’s sublimation modified ...