Extended Abstract Abstract In this article we take a rather diierent view on models for real-time systems. First of all, transitions are not instantaneous. They really bear time changes. Secondly, the model is of geometric inspiration (following the intuitions of 16]). It is intuitively clearer than other models in that executions can really be pictured as curves (or \trajectories"). Finally it...

Fuel for thought. A better measure of exposure to jet fuel shows that some military personnel may be at increased risk for adverse health effects from breathing noxious fumes. In this issue, Steve Wing, an associate professor of epidemiology in the School of Public Health at the University of North Carolina at Chapel Hill, and colleagues investigate environmental injustice in North Carolina's s...

T he ribosome plays a universally conserved role in catalyzing the translation of all mRNAs in every cell across all kingdoms of life. It is therefore not surprising that the ribosome is considered one of the most complex and elaborately formed “molecular machines” in the cell, whose biogenesis is extraordinarily orchestrated, requiring all three RNA polymerases and more than 150 nonribosomal f...

Spring gardens will soon bloom with an abundance of flowering plants—from cultivated roses to hillside wildflowers. The diversity among flowering plants is remarkable, and even within a single plant, you find an assortment of shapes and sizes. Plant organs—leaves and petals, for instance—clearly have distinct forms and functions and are subject to different evolutionary pressures. Yet scientist...

Plasma digoxin concentrations on admission to hospital have been compared with levels on day 8 in a group of 50 patients who were maintained on their preadmission digoxin doses for 7 days. In the absence of a change in renal function, 18 patients (36%) had higher levels on day 8 and were considered to be non-compliant: a further 7 patients (14%) had lower levels on day 8 suggesting that before ...

Several authors have considered take-away games where the players alternately remove a positive number of counters from a single pile, the player removing the last counter being the winner. On his initial move, the first player may remove any number of counters, so long as he leaves at least one. On each subsequent move, a player may remove at most f(n) counters, where n is the number of counte...

Animals successfully navigate the world despite having only incomplete information about behaviorally important contingencies. It is an open question to what degree this behavior is driven by estimates of stochastic parameters (brain-constructed models of the experienced world) and to what degree it is directed by reinforcement-driven processes that optimize behavior in the limit without estima...