Periodical cicadas (Magicicada spp.) are insect herbivores that feed on host tree roots, but their distribution among hosts is determined largely by the oviposition of female cicadas in the previous generation. A pattern of decreasing tree growth rates with increasing cicada densities is predicted when considering the costs of chronic root herbivory, but the opposite pattern is expected when co...

We give a rigorous analysis of variations of the contact process on a finite graph in which the cure rate is allowed to vary from one vertex to the next, and even to depend on the current state of the system. In particular, we study the epidemic threshold in the models where the cure rate is proportional to the degree of the node or when it is proportional to the number of its infected neighbors.

As graph models are applied to more widely varying fields, researchers struggle with tools that are at times too general or too specific for their needs. The Zoomgraph system attempts to address this issue by allowing users to define graphs with complex node and edge attributes, and providing a command and scripting language to manipulate and explore these graphs. The tool, which is publicly av...

In this paper we generalize the framework of linear loop transformations in the sense that loop alignment is considered as a new component in the transformation process. The aim is to match the structure of loop nests with the data distribution and alignment in order to eliminate non-local references whenever possible when compiling a sequential program for a distributed memory machine. The ali...

Suppose (S, ∗) is a mathematical structure on a set S. As examples, (S, ∗) might be a topological space on S, a topological group on S, an n-ary operator on S, an n-ary relation on S or a Steiner triple system on S. A similarity mapping on (S, ∗) is a permutation on S that preserves the structure of (S, ∗). Such mappings f : (S, ∗) → (S, ∗) are called by different names. As examples, f might be...

on S, an n-ary operator on S or a Steiner triple system on S. A similarity mapping on (S, ∗) is a permutation of S that preserves the structure of (S, ∗) . Such mappings f : (S, ∗) → (S, ∗) are called by different names. As examples, f might be called a homeomorphism or an automorphism on (S, ∗). Suppose (S, ·) is a group on S. For each t in S, the left and right translations on S are permutati...