Many natural language processing systems employ t ruth conditional knowledge representations (%ret)resentations' , etc.) to represent meanings of nata rm language expressions. T-representations have their strong and their weak sides. A strong side is logic: a relation of logical consequence can be de-. fined between such representations. A weak side is e x p r e s s i v e p o w e r : the capaci...

Lipids heading toward lysosomes that carry a mutated ion channel are spared from destruction, according to Meidel et al. (page 1477). The accumulating undigested fat eventually dooms the cell. Cells get rid of excess fat, which comes from worn-out organelles or engulfed pathogens by, for instance, shuttling them in endosomes to degradative lysosomes. The two organelles are thought to fuse when ...