What Makes a Computation Unconventional?

A coherent mathematical overview of computation and its generalisations is described. This conceptual framework is sufficient to comfortably host a wide range of contemporary thinking on embodied computation and its models.Comment: Based on an invited lecture for the 'Symposium on Natural/Unconventional Computing and Its Philosophical Significance' at the AISB/IACAP World Congress 2012, University of Birmingham, July 2-6, 201

The Computability-Theoretic Content of Emergence

In dealing with emergent phenomena, a common task is to identify useful descriptions of them in terms of the underlying atomic processes, and to extract enough computational content from these descriptions to enable predictions to be made. Generally, the underlying atomic processes are quite well understood, and (with important exceptions) captured by mathematics from which it is relatively easy to extract algorithmic con- tent. A widespread view is that the difficulty in describing transitions from algorithmic activity to the emergence associated with chaotic situations is a simple case of complexity outstripping computational resources and human ingenuity. Or, on the other hand, that phenomena transcending the standard Turing model of computation, if they exist, must necessarily lie outside the domain of classical computability theory. In this article we suggest that much of the current confusion arises from conceptual gaps and the lack of a suitably fundamental model within which to situate emergence. We examine the potential for placing emer- gent relations in a familiar context based on Turing's 1939 model for interactive computation over structures described in terms of reals. The explanatory power of this model is explored, formalising informal descrip- tions in terms of mathematical definability and invariance, and relating a range of basic scientific puzzles to results and intractable problems in computability theory

Localization of actin in Dictyostelium amebas by immunofluorescence

Antibody prepared against avian smooth muscle actin has been used to localize actin in the slime mold, Dictyostelium discoideum. The distribution of actin in migrating cells is different from that in feeding cells. Migrating amebas display fluorescence primarily in advancing regions whereas feeding amebas show uniform fluorescence throughout. The reaction is specific for actin since the fluorescence observed is blocked when the antibody is absorbed by actin purified from avian skeletal muscle, human platelets, and Dictyostelium. These results, in addition to describing the distribution of actin in D. discoideum, demonstrate that actins from these diverse sources share at least one common antigenic determinant

Clinical and radiographic observation of the periodontium in patients undergoing orthodontic therapy: first twenty-seven months

Thesis (MSD) --Boston University (Periodontics).Includes bibliographic references: leaves 84-89.Twenty-two male patients from 12-14 years of age were selected prior to active orthodontic therapy at Boston University School of Graduate Dentistry's Departmant of Orthodontics. These patients were projected to undergo full-banded orthodontic treatnent. The objective of this investigation was designed as a long tenn project to document the quantitative and qualitative changes occurring in the periodontium during and following orthodontic therapy. The patients were examined for the first 9 month period by Dr. Stuart Sears and Dr. Sergio Tejedor-Leon. Relocation of two families reduced the number of patients to twenty which were examined for the second 9 nonth period by Dr. Robert E. Roe and Dr. Robert P. Rubins. [TRUNCATED