Marr's distinction between three levels of explanation of a computational system has become a familiar part of the methodology of cognitive science. Marr distinguishes between the top level of computational theory, the middle level of representation and algorithm, and the bottom level of hardware implementation, and claims that we understand an information-processing system completely only when...

The contribution of regulatory genes to fluoroquinolone resistance was studied with clinical Escherichia coli strains bearing mutations in gyrA and parC and with different levels of fluoroquinolone resistance. Expression of marA and soxS was evaluated by Northern blot analysis of isolates that demonstrated increased organic solvent tolerance, a phenotype that has been linked to overexpression o...

David Marr's book Vision attempted to formulate athoroughgoing formal theory of perception. Marr borrowed much of the "computational" level from James Gibson: a proper understanding of the goal of vision, the natural constraints, and the available information are prerequisite to describing the processes and mechanisms by which the goal is achieved. Yet, as a research program leading to a comput...

Bacteroides fragilis is the strict anaerobic bacteria most commonly found in human infections, and has a high mortality rate. Among other virulence factors, the remarkable ability to acquire resistance to a variety of antimicrobial agents and to tolerate nanomolar concentrations of oxygen explains in part their success in causing infection and colonizing the mucosa. Much attention has been give...

Although Broadbent concedes that we are probably correct in supposing that memory representations are distributed, he argues that psychological evidence is irrelevant to our argument because our point is relevant only at what Marr (1982) has called the implementation^ level of description and that psychological theory is only properly concerned with what Marr calls the computational level. We b...

Food habits are not static and never have been (Braudel, 1973; Burnett, 1979). An enormous number of factors influence both the choice and use of different foodstuffs. To claim that eating habits do not or cannot change (Marr and Morris, 1982; Marr, 1983) is to ignore history. Since the Second World War the average family has spent a decreasing proportion of the household budget on food-over 30...