Here we elucidate a paradox: how a single chemoattractant‐receptor system in two individuals is used for communication despite the seeming inevitability of self‐excitation. In the filamentous fungus Neurospora crassa, genetically identical cells that produce the same chemoattractant fuse via the homing of individual cell protrusions toward each other. This is achieved via a recently described “ping‐pong” pulsatile communication. Using a generic activator‐inhibitor model of excitable behavior, we demonstrate that the pulse exchange can be fully understood in terms of two excitable (...) systems locked into a stable oscillatory pattern of mutual excitation. The most puzzling properties of this communication are the sudden onset of oscillations with final amplitude, and the absence of seemingly inevitable self‐excitation. We show that these properties result directly from both the excitability threshold and refractory period characteristic of excitable systems. Our model suggests possible molecular mechanisms for the ping‐pong communication. (shrink)

This book contains a rich, interdisciplinary collection of articles by some of the pioneers of contemporary research on attention.

In Chapters 6 and 7 of Language, Truth and Poetry I attempted to solve the ancient problem of fictional reference by claiming that a fictional construct ‘points’ or refers to certain features of reality in rather the same way as an abstraction like ‘gravitation’ or ‘cruelty’ does. I now believe that this theory of mine is unsatisfactory; and I should like to propose a new solution to the problem.

In 1773, Pope Clement XIV suppressed the Society of Jesus, a dramatic, puzzling act that had a profound impact. This volume traces the causes of the attack on the Jesuits, the national expulsions that preceded universal suppression, and the consequences of these extraordinary developments. The Suppression occurred at a unique historical juncture, at the high-water mark of the Enlightenment and on the cusp of global imperial crises and the Age of Revolution. After more than two centuries, answers to how and (...) why it took place remain unclear. A diverse selection of essays - covering France, Spain, Portugal, Italy, the Netherlands, China, Eastern Europe, and the Americas - reflects the complex international elements of the Jesuit Suppression. The contributors shed new light on its significance by drawing on the latest research. Essential reading on a crucial yet previously neglected topic, this collection will interest scholars of eighteenth-century religious, intellectual, cultural, and political history. (shrink)

Recently, Quyn et al. demonstrated that cells within the stem cell zone of human and mouse intestinal crypts tend to align their mitotic spindles perpendicular to the basal membrane of the crypt. This is associated with asymmetric division, whereby particular proteins and individual chromatids are preferentially segregated to one daughter cell. In colonic mucosa containing a heterozygous adenomatous polyposis coli gene (APC) mutation the asymmetry is lost. Here, we discuss asymmetric stem cell division as an anti‐tumourigenic mechanism. We describe how (...) hierarchical tissue structures suppress somatic evolution, and discuss the relative merits of template strand retention to limit the accumulation of DNA replication errors. We suggest experiments to determine whether somatic mutations resulting in loss of spindle alignment confer an advantage within the stem cell niche. Finally, we discuss whether lack of spindle alignment constitutes an oncogenic event per se, with particular reference to studies in model organisms, and the timing of chromosomal instability in human cancers. (shrink)

We discuss our surgical philosophy concerning the subtle interplay between the size of the surgical margin taken and the resultant morbidity from ablative oncological. procedures, which is ever more evident in the treatment of head and neck malignancy. The extent of tissue resection is determined by the "trade off" between cancer control and the perioperative, functional and aesthetic morbidity and mortality of the surgery. We also discuss our dilemmas concerning recent minimally invasive endoscopic microsurgical. techniques for the trans-oral laser removal. (...) or co-ablation of aero-digestive tract tumours, which result in a minimal. surgical margin of oncological clearance. By a process of inductive argument as to the nature of the surgical margin, we consider whether the risks of taking a lesser margin with adjuvant therapy is justified by the attendant gain in reduced surgical morbidity and the possible costs in tumour control. (c) 2006 Elsevier Ltd. All rights reserved. (shrink)

Photography has become a pervasive component of contemporary communication. Recent technological advances in creating and manipulating images have provided renewed impetus to decades-long debates on use of photographs in science. With increase in the potential for inappropriate image manipulation, fears about misrepresentation have heightened concern among journal editors and scholars about the 'accuracy' of published images. We discuss how science has responded to growing concerns surrounding falsification and inaccuracy of photography. We document progress in implementing a variety of complementary approaches (...) to addressing the problem. These include digital forensics, photo member checking and the implementation of codes of ethics to enhance the veracity of published photographs in science research. We conclude by acknowledging the irreducible conflict likely to remain between use of the photograph as a creative work of art and employment of this medium as a source of information in the progress of science. (shrink)

This book is a succinct introduction to the orienting of attention.

This paper provides a survey of philosophical discussion of the "the Turing Test". In particular, it provides a very careful and thorough discussion of the famous 1950 paper that was published in Mind.

The foundations of systematics lie in ontology, not in subjective epistemology. Systems and their elements should be distinguished from classes; only the latter are constructed from similarities. The term classification should be restricted to ordering into classes; ordering according to systematic relations may be called systematization.The theory of organization levels portrays the real world as a hierarchy of open systems, from energy quanta to ecosystems; followingHartmann these systems as extended in time are considered the primary units of reality. Organization levels (...) should be distinguished from levels of differentiation within each organization level.Certain biological systems, such as species, continue to be misinterpreted as classes, particularly by logicians unfamiliar with modern biological theory. Replacement of Aristotelian definitions of species by “polytypic” definitions achieves nothing, because species are individual systems which can be defined from an ontological viewpoint only as wholes. The dispute whether classes are real per se or only in individuals is of no scientific importance; irrespective of which view is taken, any ordering of physical objects into classes constitutes an hypothesis about the structure of the real world.The distinction between essential and contingent characters is relevant only to classification. There are no universal rules for evaluating characters for purposes of systematization. Character statements do not form separate linear sequences. The search for “unit characters” in an absolute sense is futile. All real characters are reducible to relations and are in principle measurable, although there are limitations on the extent to which this can be presently achieved.The concept of the sexual species is fundamental to theories of biosystematics. Sexual species may be defined as lineages consisting at any given time of series of populations between which genetic exchange can occur and delimited in time by two successive processes of speciation. Linnaean nomenclature needs modification; in its traditional form it is appropriate only to non-truncated hierarchies, whereas real phylogenies form truncated hierarchies. In consequence of the distinction between systematization and classification it is concluded that, while taxa may be classified into age classes or evolutionary grades, their limits as taxa can be no different in either case. Classification into evolutionary grades remains an imprecise endeavour, since no general measure of evolutionary differentiation has been devised.The spatial and temporal extent of ecosystems, the postulated basic units of ecosystematics, remains unclarified. Nevertheless there are grounds for expecting progress in this field as the energetic relations between organisms become better understood. Biotic communities are not “abstract” classes, but systematic units. Physiognomic classification should not be confused with systematization of plant communities; both approaches contribute to an understanding of vegetational structure. (shrink)

There is some complementarity of models for the origin of the electroencephalogram (EEG) and neural network models for information storage in brainlike systems. From the EEG models of Freeman, of Nunez, and of the authors' group we argue that the wavelike processes revealed in the EEG exhibit linear and near-equilibrium dynamics at macroscopic scale, despite extremely nonlinear – probably chaotic – dynamics at microscopic scale. Simulations of cortical neuronal interactions at global and microscopic scales are then presented. The simulations depend (...) on anatomical and physiological estimates of synaptic densities, coupling symmetries, synaptic gain, dendritic time constants, and axonal delays. It is shown that the frequency content, wave velocities, frequency/wavenumber spectra and response to cortical activation of the electrocorticogram (ECoG) can be reproduced by a “lumped” simulation treating small cortical areas as single-function units. The corresponding cellular neural network simulation has properties that include those of attractor neural networks proposed by Amit and by Parisi. Within the simulations at both scales, sharp transitions occur between low and high cell firing rates. These transitions may form a basis for neural interactions across scale. To maintain overall cortical dynamics in the normal low firing-rate range, interactions between the cortex and the subcortical systems are required to prevent runaway global excitation. Thus, the interaction of cortex and subcortex via corticostriatal and related pathways may partly regulate global dynamics by a principle analogous to adiabatic control of artificial neural networks. (shrink)

A laboratory-testable, solid-state Maxwell demon is proposed that utilizes the electric field energy of an open-gap p-n junction. Numerical results from a commercial semiconductor device simulator (Silvaco International–Atlas) verify primary results from a 1-D analytic model. Present day fabrication techniques appear adequate for laboratory tests of principle.

Natural law political theory grounds the authority of law in the law's capacity to advance the common good, but questions about what this common good is and how it relates to political life remain highly contested. The influential new natural law theory of John Finnis reduces political association to the operation of government and makes it a merely instrumental good that serves to secure and facilitate individual and social goods. Political community, on this account, does not realize any further human (...) good not already experienced in smaller human communities. In A Vindication of Politics, Matthew Wright challenges this account and argues that political community itself realizes an aspect of social life intrinsic to full human flourishing. Wright develops an account of the political common good that is both inclusivist and distinctive--that is to say, it includes within its orbit the diverse goods of individuals and other associations, and it recognizes the good of the political association itself. Drawing on the work of Edmund Burke and the example of Abraham Lincoln, Wright argues that political community has its own distinctive goods, including civic friendship and political culture, embodied in its history, institutions, practices, and ideals. Individuals do not have to run for office to be engaged in the political common good. Participation in the vibrant cultural life of one's political community is an intrinsic part of the common good. (shrink)

A number of studies in the apparent motion literature were examined using the cognitive penetrability criterion to determine the extent to which beliefs affect the perception of apparent motion. It was found that the interaction between the perceptual processes mediating apparent motion and higher order processes appears to be limited. In addition, perceptual and inferential beliefs appear to have different effects on perceived motion optimality and direction. Our findings suggest that the system underlying apparent motion perception has more than one (...) stage and is informationally encapsulated from cognitive factors. (shrink)

From Galileo to the Bhopal tort litigation, Scopes to OncoMouse®, Lysenko to the lie detector, the agonistic and alethic forum of the courtroom has offered unique opportunities to witness science and scientists being made and unmade. Evolving legal systems have consistently been forced to draw on (or defensibly away from) scientific knowledge, scientific methods, and scientific experts in the pursuit of truth and justice. At the same time, courts—in many ways the original site for the production of social facts—have to (...) a significant extent shaped both the theories and the practices of knowledge production central to the emergence of modern science. This Focus section draws together a set of scholars at work on these borrowings and aims to stimulate more research in an important and fast‐expanding area of scholarship. (shrink)

Annotation Presents historical methodology to augment the critical capacity of research on black history.

We outline fresh findings that show that our macroscopic electrocorticographic (ECoG) simulations can account for synchronous multiunit pulse oscillations at separate, simultaneously activated cortical sites and the associated gamma-band ECoG activity. We clarify our views on the approximations of dynamic class applicable to neural events at macroscopic and microscopic scales, and the analogies drawn to classes of ANN behaviour. We accept the need to introduce memory processes and detailed anatomical and physiological information into any future developments of our simulations. On (...) the issue of intrinsic cortical stability and the role of extrinsic fibre systems in maintaining stability, we argue that this position is not in extreme contradiction to those of our commentators, and that the mechanisms implicit in our simulations' properties imply rich computational possibilities. We discuss some of the reasons for and against the existence of significant global resonances in the brain and explain why such behaviour appears absent in our simulations. Last, we discuss other phenomena, such as rhythmic driving of the cortex, which have not yet been introduced into our models, and indicate lines for future development of the simulations. (shrink)