The human visual system is remarkably tolerant to degradation in image resolution: human performance in scene categorization remains high no matter whether low-resolution images or multimegapixel images are used. This observation raises the question of how many pixels are required to form a meaningful representation of an image and identify the objects it contains. In this article, we show that...

recognition. The key role of cholesterol metabolism in cardiovascular diseases has been accepted long ago; emerging evidence now supports the central role of cholesterol metabolism in neurodegenerative, metabolic, skin and infectious diseases. Cellular cholesterol content has to be maintained within tight limits, or else; not surprisingly, therefore, a number of regulatory mechanisms provide mu...

Every manufacturer is confronted with the problem of finding the most economical quantity to manufacture in putting through an order. This is a general problem and admits of a general solution, and, however much it may be advisable to exercise judgment in a particular case, such exercise of judgment will be assisted by a knowledge of the general solution. The writer has seen the practical worki...

Desert ants have a sequence of optimized behaviours that allow them to forage efficiently. Recent work shows that after using navigational memories to reach previously rewarding areas, ants follow long crosswind sweeps that appear adapted for encountering odour plumes.