A player moving in the plane is given a sequence of instructions of the following type: at step i a planar convex set Fi is specified, and the player has to move to a point in Fi. The player is charged for the distance traveled. We provide a strategy for the player which is competitive, i.e., for any sequence Fi the cost to the player is within a constant (multiplicative) factor of the "off-lin...

Although we know enormous amounts of detailed information about the neurons that make up the cortex, placing this information back into the context of the behaving animal is a serious challenge. The functional cell assembly hypothesis first described by Hebb (The Organization of Behavior; a Neuropsychological Theory. New York: Wiley; 1949) aimed to provide a mechanistic explanation of how group...

The UK and its anxious neighbours are currently focusing on foot and mouth disease but agricultural researchers are still working on a much deeper and worrying problem: BSE and its human form, new variant CJD. Unlike foot and mouth disease, much remains unknown about the aberrant prion protein agent of BSE and how it causes disease. One of the biggest stumbling blocks to research is the lack of...

Basic research on biodiversity has concentrated on individual species-naming new species, studying distribution patterns, and analyzing their evolutionary relationships. Yet biodiversity is more than a collection of individual species; it is the combination of biological entities and processes that support life on Earth. To understand biodiversity we must catalog it, but we must also assess the...

Edge-chasing is the basis of many deadlock detection algorithms. This method detects a deadlock by propagating special messages called probes along dependency edges. When the initiator of a probe receives the probe back, it knows the existence of a deadlock. Once a deadlock is detected, a special message called token is sent to clean up those probes in the deadlock cycle which, if not removed, ...

A Quick guide to Love Spots: striking male-specific regions of the eye found in some insects that are used for detecting and chasing females.