Properties of Cooperatively Induced Phases in Sensing Models

A large number of eukaryotic cells are able to directly detect external chemical gradients with great accuracy and the ultimate limit to their sensitivity has been a topic of debate for many years. Previous work has been done to understand many aspects of this process but little attention has been paid to the possibility of emergent sensing states. Here we examine how cooperation between sensors existing in a two dimensional network, as they do on the cell's surface, can both enhance and fundamentally alter the response of the cell to a spatially varying signal. We show that weakly interacting sensors linearly amplify the sensors response to an external gradient while a network of strongly interacting sensors form a collective non-linear response with two separate domains of active and inactive sensors forming what have called a "1/2-state" . In our analysis we examine the cell's ability to sense the direction of a signal and pay special attention to the substantially different behavior realized in the strongly interacting regime.Comment: 8 pages, 5 figure

In Praise of Diversity

This is the publisher's official version, which the author has obtained special permission to share

Annihilated Spaces: American Literature and American Society

Annihilated Space uses American literature to understand our social history. Flexible and inclusive, it shows multiple ways in which national fiction, drama, journals and poetry reveal us. The study builds upon a lifetime of scholarship and experience in areas as diverse as contemporary conditions among Native American peoples, the social structure of the audience for “classical” music, the history of American art, street life in Mexico City and, of course, American literature and the American experience. It suggests approaches that “work” even on pieces set outside the United States, in one case revealing American social history in a novel with no American characters. Some works treated in this lively discussion are acknowledged masterpieces. A few are things critics generally dislike—but they can be entertaining to discuss, and very useful to an open-minded student of society

Communications

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