Packing tripods: Narrowing the density gap

Packing tripods: Narrowing the density gap

In 1984, S. K. Stein and his co-authors posed a problem concerning simple three-dimensional shapes, known as semicrosses, or tripods. By definition, a tripod is formed by a corner and the three adjacent edges of an integer cube. How densely can one fill the space with nonoverlapping tripods of a given size? In particular, is it possible to fill a constant fraction of the space as the tripod siz...

Narrowing the gap.

Since 1981 AIDS has illuminated, like a roving searchlight, a series of ethical questions, which extend far beyond the apparently narrow limits of one disease. It has revealed, one by one, human attitudes and behaviours that were previously unquestioned, or unobserved based on unidentified but shaky pre-suppositions. This commentary oVers two contrasting perspectives on the problems facing deve...

Narrowing the Nutrition Gap:

Narrowing the Explanatory Gap with Bridge Metaphors

A central problem in philosophy of mind concerns the relationship between subjective experiences and the physical processes that subserve them. There seems to be an unbridgeable “explanatory gap” between the two. Whereas other scientific explanations (e.g. the explanation of temperature in terms of kinetic energy) involve determinate relationships between two kinds of phenomena, correlations be...

Narrowing the US energy efficiency gap.

T he energy-efficiency gap has puzzled researchers and policy makers for decades (1). Changes in behavior and the use of efficient technologies could substantially reduce energy consumption, yielding strong financial returns. However, householders, business managers, and government officials fail to take advantage of the opportunity. Attari et al. (2) reveal important features of the gap by an ...