Specific impairments in cognitive development: a dynamical systems approach

Neuropsychologists have frequently proposed that domain-specific deficits can be observed in developmental disorders (e.g., phonology in dyslexia, theory of mind in autism, grammar in specific language impairment, face recognition in prosopagnosia, mathematics in dyscalculia). These deficits appeal to a modular cognitive architecture. However, specific developmental deficits are at odds with theories that posit a high degree of interactivity between cognitive abilities across development. If there are early deficits, why do these not spread across the cognitive system during development? Or experience compensatory help from other initially intact components? We address these questions within a dynamical systems framework (van der Maas et al., 2006). We explore the conditions for deficit spread and compensation for a range of possible cognitive architectures, from modular to fully distributed. While preliminary, the results point to the importance of specifying precisely the normal developmental architecture of a system prior to characterizing patterns of impairment that might emerge from it

An Actuarial Analysis of the Production Function of Major League Baseball

The majority of major league baseball production function studies have utilized data (nonstandardized and standardized) from only one baseball season. This research study utilized data from the 1980-1984 baseball seasons. The results indicate that factors contributing to victories fluctuate. Consistent with prior research, this study found batting average, manager\u27s career win-loss record and the strike-out-to-walk ratio to be the most significant factors contributing to victories. Inconsistent with prior research, this study found that fielding average can also be significant

USING REAL OPTIONS TO EVALUATE PRODUCER INVESTMENT IN NEW GENERATION COOPERATIVES

New Generation Cooperatives have emerged as a contemporary means for farmers to invest in further processing activities. This paper considers real options as the basis for evaluating producer investment in a start-up cooperative that involves technological uncertainty. The investment and risk inherent in producer membership in an NGC is analyzed using real options theory logic. Real options theory has recently been extended to technology positioning projects and how the extent of uncertainty influences the value of a technology "option". Conventional net present value formulas have been shown to be limited when the conditions of the investment require substantial commitment under uncertainty, such as investments in technology. Implications for producers are drawn from the analysis. Producers always have the alternative of not investing in the initial start-up but waiting and buying in at a later time, perhaps when less uncertainty prevails. Results indicate that producers are better able to evaluate investment in a NGC using real options.Agribusiness,

Color Superconductivity at Large N: A New Hope

At zero density, the `t Hooft large N_c limit often provides some very useful qualitative insights into the non-perturbative physics of QCD. However, it is known that at high densities the `t Hooft large N_c world looks very different from the N_c=3 world, which is believed to be in a color superconducting phase at high densities. At large N_c, on the other hand, the DGR instability causes a chiral-density wave phase to dominate over the color superconducting phase. There is an alternative large N_c limit, with the quarks transforming in the two-index antisymmetric representation of the gauge group, which at N_c=3 reduces to QCD but looks quite different at large N_c. We show that in this alternative large N_c limit, the DGR instability does not occur, so that it may be plausible that the ground state of high-density quark matter is a color superconductor even when N_c is large. This revives the hope that a large N_c approximation might be useful for getting some insights into the high-density phenomenology of QCD.Comment: 8 pages, 1 figur