Nucleation and motion of kink pairs on partial dislocations are examined by elasticity theory for materials with a high Peierls stress. Two approaches are used: one considers the change in average stacking-fault energy due to alloying elements and the other considers the change in local SFE due to a nearby solute atom. Both approaches highlight the role of SFE on kink nucleation, propagation and annihilation and both furnish strain rate as a function of stress, temperature and SFE. Model predictions are (...) compared with yield stress data for two systems: firstly, an intermetallic, MoSi 2 , which softens for alloying elements that decrease the SFE and hardens for Re additions that increase the SFE; secondly, a ceramic oxide, MgO-Al 2 O 3 spinel, which softens with increasing addition of excess alumina and at the same time exhibits a decrease in SFE. The average SFE approach agrees qualitatively with the data while quantitative agreement is obtained with the local SFE approach. The possibility is considered that the model applies to other materials, such as TiAl, HfV 2 and Fe 3 Al, which show softening with certain alloying additions. One requirement is that the dislocations are dissociated more than a few atomic distances; otherwise kink nucleation occurs on the perfect dislocation . Hence the model does not apply to materials such as bcc metals which only have a core dissociation. Normal hardening effects of solutes from size and modulus misfits are additive with any softening effects from a decrease in SFE and so may mask the latter, as occurs for W additions to MoSi 2. (shrink)

This study investigated the performance of boys with psychopathic tendencies and comparison boys, aged 9 to 17 years, on two tasks believed to be sensitive to amygdala and orbitofrontal cortex func- tioning. Fifty-one boys were divided into two groups according to the Psychopathy Screening Device (PSD, P. J. Frick & R. D. Hare, in press) and presented with two tasks. The tasks were the gambling task (A. Bechara, A. R. Damasio, H. Damasio, & S. W. Anderson, 1994) and the Intradimensional/ (...) Extradimensional (ID/ED) shift task (R. Dias, T. W. Robbins, & A. C. Roberts, 1996). The boys with psychopathic tendencies showed impaired performance on the gambling task. However, there were no group differences on the ID/ED task either for response reversal or extradimensional set shifting. The implications of these results for models of psychopathy are discussed. (shrink)

In video games, identification with avatars—virtual entities or characters driven by human behavior—has been shown to serve many interpersonal and intraindividual functions but our understanding of the psychological variables that influence players' avatar choices remains incomplete. The study presented in this paper tested whether players' preferred style of avatar creation is linked to the magnitude of self-perceived discrepancies between who they are, who they aspire to be, and who they think they should be. One-hundred-and-twenty-five undergraduate gamers indicated their preferred avatar (...) creation style and completed a values measure from three different perspectives: their actual, ideal, and ought selves. The average actual/ideal values discrepancy was greater among those who preferred idealized avatars vs. those who preferred realistic avatars. The average actual/ought values discrepancy was greater among those who preferred completely different avatars vs. those who preferred realistic avatars. These results, therefore, offer additional evidence that self-discrepancy theory is a useful framework for understanding avatar preferences. (shrink)

The function of Metaphysics is to furnish an intelligible and significant perspective. The tendency of recent speculation is to abstain from the attempt to give a total or absolute perspective of the world as a unit—there is some question as to whether we can think of the world as a whole—but rather to understand the objects about us, to bring values, formerly located in a transcendental realm, into life and conduct here and now, and to broaden our understanding and interests (...) to included related activities and other communities. To make our perspective within a single science intelligible it is necessary, as Professor Miller has demonstrated, to fill in the gaps between perceptual objects with inexperienceable “interphenomena” and to employ methodological concepts and principles derived by abstraction and inference. Then again, each of the special sciences selects certain aspects of the general perspective for intensive research leaving gaps between the sciences to be filled in by integrating concepts. Finally, values emerge at the various levels, and these need to be related to the conditions out of which they arise and to the fields of applied knowledge in which they function. (shrink)

It is strange to write for the pages of this journal a statement which will not come under the eye of its founding editor, Sheldon Sacks. For nearly five years everything that appeared in Critical Inquiry—articles, critical responses, editorial comments—was a matter of painstaking and passionate concern to Shelly Sacks. With a flow of questions and suggestions and a talent for unabashed cajolery, he generated articles and rejoinders to those articles. He worked tirelessly in editorial consultation and correspondence with contributors, (...) especially young writers, helping them to discover the best way of giving form to their ideas. Among the essays submitted to this journal he searched eagerly, even anxiously, for those which seemed, in his words, "right for C.I." What was right for C. I. was never, for Shelly Sacks, a cut-and-dried choice. In his own intellectual life, in his teaching and writing, he delighted in arguing important general questions: theories of representation in the arts, points of possible intersection between linguistic science and literary criticism, the interplay of social forces and cultural expressions. Not surprisingly, in reconnoitering for Critical Inquiry, he found special satisfaction in identifying writers who shared his passion for reexamining fundamental topics in the intellectual disciplines. If such writers made their case forcefully, so much the better: in choosing an essay for publication he assessed its capacity to stimulate interesting counterargument. At no time, however, did Shelly Sacks confuse his own beliefs with the nature of intellectual discourse. As an editor he was hospitable to writers whose premises he questioned and whose conclusions he deplored. Nor did Shelly attempt to achieve a spurious catholicity by following a quiet quota system designed to give each major line of interpretation—deconstructionist, Marxist, psychoanalytic, what have you—an occasional airing in Critical Inquiry. For Shelly each article stood on its own ground: if its author dealt responsibly and freshly with an interesting problem, that was enough. And, along with his commitment to theoretical inquiry, he responded warmly to the personal, the offbeat, the idiosyncratic. He regarded the feature Artists on Art, for example, as a central element in our design. As an editor Sheldon Sacks was above all a shaper. He labored to find and suggest connections in the phenomena of intellectual life. Even the construction of a table of contents for a typical Critical Inquiry issue became for him an opportunity to influence the reader's experience of what we offered. The eminence of an author or the allure of a title were put to one side as Shelly sought to orchestrate, through placement, a kind of intellectual counterpoint from one essay to another. Unheard melodies, doubtless, for many of us, but for Shelly real and sustaining. In this valedictory note we have spoken of Sheldon Sacks' editorial accomplishment—in our friendly view, a very distinguished one—rather than of the personal qualities which made working alongside him an exhilarating experience. We should report, however, that for more than half the life of this journal Shelly was ill and knew that the time available to him was likely to be relatively brief. Faced with this diminishing perspective, he did not—indeed it is more accurate to say he could not—moderate his involvement with the life of this journal. At his death, as at the launching of this enterprise, he held to the high ambition that Critical Inquiry encourage comeliness, vigor, and continuity in the discourse of our time. The appropriate "critical response" to this great loss is that Sheldon Sacks’ editorial colleagues, and our publisher, the University of Chicago Press, pledge whatever talents and energies we possess to the continuing life of the journal he imagined and brought into being. (shrink)