It is often held that although explicit learning declines in the course of normal aging, implicit learning is relatively preserved. Here we summarize research from our group which leads us to argue that some forms of implicit learning do decline with adult age. In particular, we propose that there are age-related declines in implicit learning of probabilistic sequential relationships that occur across the adult lifespan, and that they reflect, at least in part, age-related striatal dysfunction. We first review behavioral evidence (...) supporting this age-related decline and then evidence from patient groups, genetics, and neuroimaging supporting this striatal dysfunction hypothesis. (shrink)
Computational models of semantic memory exploit information about co-occurrences of words in naturally occurring text to extract information about the meaning of the words that are present in the language. Such models implicitly specify a representation of temporal context. Depending on the model, words are said to have occurred in the same context if they are presented within a moving window, within the same sentence, or within the same document. The temporal context model (TCM), which specifies a particular definition of (...) temporal context, has proved useful in the study of episodic memory. The predictive temporal context model (pTCM) uses the same definition of temporal context to generate semantic memory representations. Taken together pTCM and TCM may prove to be part of a general model of declarative memory. (shrink)
A key question in understanding microtubule dynamics is how GTP hydrolysis leads to catastrophe, the switch from slow growth to rapid shrinkage. We first provide a review of the experimental and modeling literature, and then present a new model of microtubule dynamics. We demonstrate that vectorial, random, and coupled hydrolysis mechanisms are not consistent with the dependence of catastrophe on tubulin concentration and show that, although single-protofilament models can explain many features of dynamics, they do not describe catastrophe as a (...) multistep process. Finally, we present a new combined (coupled plus random hydrolysis) multiple-protofilament model that is a simple, analytically solvable generalization of a single-protofilament model. This model accounts for the observed lifetimes of growing microtubules, the delay to catastrophe following dilution and describes catastrophe as a multistep process. (shrink)
The 2006 outbreak of E. coli O157:H7, traced to bagged spinach from California, illustrates a number of contradictions. The solutions sought by many politicians and popular food analysts have been to create a centralized federal agency and a uniform set of production standards modeled after those of the animal industry. Such an approach would disproportionately harm smaller-scale producers, whose operations were not responsible for the epidemic, as well as reduce the agroecological diversity that is essential for maintaining healthy human beings (...) and ecosystems. Why should responses that only reinforce the problem be proffered? We use the framework of accumulation and legitimation to suggest corporate and government motives for concealing underlying problems and reinforcing powerful ideologies of individualism, scientism, and centralizing authority. Food safety (or the illusion of safety) is being positioned to secure capital rather than public welfare. We propose implementing the principle of subsidiarity as a more democratic and decentralized alternative. Because full implementation of this principle will be resisted by powerful interests, some promising intermediate steps include peer production or mass collaboration as currently applied to disease prevention and surveillance, as well as studying nascent movements resisting current food safety regulations. (shrink)
Recent years have seen a substantial increase in alternative agrifood initiatives that attempt to use the market to curtail the negative social and environmental effects of production and trade in a globalized food system. These alternatives pose a challenge to capital accumulation and the externalization of environmental costs by large agribusiness, trading and retail firms. Yet the success of these alternatives also makes them an inviting target for corporate participation. This article examines these dynamics through a case study of the (...) two most significant such food system alternatives—organics and fair trade—focusing on corporate involvement in establishing and renegotiating the standards undergirding these initiatives. We compare the development of and contestation over the standards for both certified organic and certified fair trade, with particular attention to the U.S. context. We provide a brief history of their parallel processes of rapid growth and market mainstreaming. We examine claims of cooptation by movement participants, as well as the divergences and similarities between the organic and fair trade cases. Analyzing these two cases provides useful insights into the strategic approaches that corporate firms have deployed to further capital accumulation and to defuse threats to their profit margins and to status quo production, pricing, labor, trading and retailing practices. It can also offer valuable lessons regarding the most effective means of responding to such counter-reforms and of protecting or reasserting the more transformative elements at the heart of these alternative systems. (shrink)
This review essay examines H. TristramEngelhardt, Jr.'s The Foundations of Bioethics, a contemporary nonfeminist text in mainstream biomedical ethics. It focuses upon a central concept, Engelhardt's idea of the moral community and argues that the most serious problem in the book is its failure to take account of the political and social structures of moral communities, structures which deeply affect issues in biomedical ethics.
H. Tristram Engelhardt has made profound contributions to both philosophical and religious bioethics, and his philosophical and religious works may be read in mutually illuminating ways. As a philosopher, Engelhardt has mustered a powerful critique of secular efforts to develop a shared substantive morality. As a religious scholar, Engelhardt has affirmed a Christian bioethics that does not emanate from human rationality but from the experience of God found in Orthodox Christianity. In this collection of essays, both defenders and critics of (...) Engelhardt's religious bioethics have their say, and the spirited nature of their discussion attests, in its own right, to Engelhardt's enduring influence. (shrink)
The Foundations of Pragmatism in American Thought Series offers two sets of volumes containing the most significant defenses and critiques of pragmatism written before World War I: the Early Defenders of Pragmatism and Early Critics of Pragmatism . This, the first collection, Early Defenders , provides key texts for understanding the context of pragmatism’s years of greatest vitality. The early defenders were products of pragmatism’s three cradles. H. Heath Bawden was a graduate of the Chicago philosophy department, having studied with (...) John Dewey and George Mead. John E. Boodin and Horace M. Kallen earned their Ph.Ds with William James and Josiah Royce at Harvard. D. L. Murray and Howard V. Knox were independent scholars and writers inspired by F. C. S. Schiller’s humanistic pragmatism at Oxford. This collection brings together the central texts of the movement along with a representative selection of the secondary texts, reviews and responses, they elicited. Each volume features a newly-commissioned introduction by a leading scholar of American pragmatism. --five central texts reproduced in facsimile, accompanied by the main responses and replies, reset in new typography --scattered and scarce works available together for the first time --new introductions to each volume by leading scholars of American pragmatism. (shrink)