The occurence of polygonal structures is widespread in nature 1]. Extensive investigations on the statistics of two-dimensional networks have been performed for biological tissues 2, 3], clusters of metal grains 4, 5], systems of soap bubbles 6, 7, 8], emulsion lattices 9], gas bubbles in Lang-muir monolayers 10], magnetic froth 11] or convective patterns in hydrody-namics 12, 13, 14]. The stro...

^Smithsonian Tropical Research Institute, Box 2072, Balboa, Republic of Panama ^Archaeobiology Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington DC 20560, USA ^Department of Anthropology, Peabody Museum, Harvard University, 11 Divinity Avenue, Cambridge, Massachusetts 02130, USA ^Institute of Archaeology, University of Haifa, Mount Carm...

The analyses of 738 soil and sediment samples taken during the investigation of 20 forensic cases are combined in a database for retrospective comparisons. Quartz sand grain surface textures are combined into grain types which are analysed at one of five orders of classification. This classification also provides frequency data on the number of grain types found in a sample, the individuality o...

The grain procurement and marketing system was established in China in the early 1950s. The primary policy objective was to ensure equal and relatively efficient distribution of limited grain among consumers and industrial users, and to ensure the growth of grain production at the planned rate. At the same time, it was assigned another important task: to divert agricultural surplus into investm...

Epidemic outbreaks of new pathogens, or known pathogens in new populations, cause a great deal of fear because they are hard to predict. For theoretical models of disease spreading, on the other hand, quantities characterizing the outbreak converge to deterministic functions of time. Our goal in this paper is to shed some light on this apparent discrepancy. We measure the diversity of (and, thu...

These lectures will cover methods for studying the evolution of galaxies since their formation. Because the properties of a galaxy depend on its history, an understanding of galaxy evolution requires that we understand the dynamical interplay between all components over 10 gigayears. For example, lopsided (m = 1) asymmetries are transient with gigayear time scales, bars may grow slowly or sudde...

A new mechanism for the pp → ppπ reaction close to threshold is suggested coming from the isoscalar excitation of the Roper and its decay into N(ππ)s−wave, with one of the π 0 emitted and the other one reabsorbed on the second nucleon. The mechanism can lead to important interference with other mechanisms and, together with experiment, serves to exclude large ranges of the 2π N decay parameters...

This paper reconsiders the uniform sublevel set estimates of Carbery, Christ, and Wright [5] and Phong, Stein, and Sturm [17] from a geometric perspective. This perspective leads one to consider a natural collection of homogeneous, nonlinear differential operators which generalize mixed derivatives in R. As a consequence, it is shown that, in the case of both of these previous works, improved u...