Using a cognitive architecture to examine what develops

Different theories of development propose alternative mechanisms by which development occurs. Cognitive architectures can be used to examine the influence of each proposed mechanism of development while keeping all other mechanisms constant. An ACT-R computational model that matched adult behavior in solving a 21-block pyramid puzzle was created. The model was modified in three ways that corresponded to mechanisms of development proposed by developmental theories. The results showed that all the modifications (two of capacity and one of strategy choice) could approximate the behavior of 7-year-old children on the task. The strategy-choice modification provided the closest match on the two central measures of task behavior (time taken per layer, r = .99, and construction attempts per layer, r = .73). Modifying cognitive architectures is a fruitful way to compare and test potential developmental mechanisms, and can therefore help in specifying “what develops.

Health effects and related standards for fossil-fuel and geothermal power plants. Volume 6 of health and safety impacts of nuclear, geothermal, and fossil-fuel electric generation in California. [In California]

This report reviews health effects and related standards for fossil-fuel and geothermal power plants, emphasizing impacts which may occur through emissions into the atmosphere, and treating other impacts briefly. Federal regulations as well as California state and local regulations are reviewed. Emissions are characterized by power plant type, including: coal-fired, oil-fired, gas-fired, combined cycle and advanced fossil-fuel plants; and liquid and vapor geothermal systems. Dispersion and transformation of emissions are treated. The state of knowledge of health effects, based on epidemiological, physiological, and biomedical studies, is reviewed

Spectroscopic studies of Manduca sexta and Sesamia nonagrioides chorion protein structure

The secondary structure of Manduca sexta and Sesamia nonagrioides chorion proteins has been studied in intact chorions using laser-Raman and Fourier transform infra-red (FTIR) spectroscopy and in a solution containing extracted and reassembled chorion proteins using circular dichroism (CD) spectroscopy. Laser-Raman and IR spectra suggest the predominance of antiparallel β-pleated sheet structure in intact chorion proteins of both Lepidoptera species. The bands at 1673, 1674 cm-1 (amide I) and 1234-1238 cm-1 (amide III) in the laser-Raman spectra can best be interpreted as resulting from abundant antiparallel β-pleated sheet structure. Analysis of the amide I band suggests that chorion proteins consist of 60-70% antiparallel β-pleated sheet and 30-40% β-turns. Supporting evidence for the prevalence of antiparallel β-pleated sheet in chorion proteins was supplied using FTIR spectroscopy by the observation of a very intense absorption band at 1635 cm-1(amide I) and of a weak band at 1530, 1525 cm-1 (amide II) from chorions of both species. Surprisingly, analysis of the CD spectra of extracted and reassembled chorion proteins suggests that, in solution, they retain a regular secondary structure most probably dominated by β-pleated sheet. We therefore suggest that the prominent regular β-sheet structure of chorion proteins may exist in solution and dictate the aggregation and polymerization process in vivo. © 1995

Seismically induced uplift effects on nuclear power plants. Part 2: Demand on internal equipment

This work focuses on the dynamic response of nuclear power plant mechanical sub-systems (i.e., main cooling system, steam generators, emergency cooling injection tanks and piping) that are housed within the containment structure and are associated with power generation. More specifically, the numerical modeling procedure focuses on the internal R/C wall structural system used for supporting the mechanical equipment. Next, the complex grid of the mechanical components is modeled with shell finite elements. This internal equipment configuration is then excited by the ground motion numerically predicted in Part I οf this work by considering geometrically nonlinear soil-structure interaction effects. Following extensive parametric studies, the seismic demand imposed on the internal equipment is assessed on the basis of dynamic stress analysis of the critical components. Depending on frequency content of the incoming seismic motion, it is shown that abrupt uplift may take place. This is true even for moderate earthquake intensity, particularly when the containment structure rests on soft soils and the vertical component of ground motion is not negligible. This situation may produce peaks in the pipe elbow strains that could potentially affect serviceability, operation and under extreme conditions, the safety of the entire nuclear power plant

Laser-Raman and FT-IR spectroscopic studies of peptide-analogues of silkmoth chorion protein segments

Silkmoth chorion, the proteinaceous major component of the eggshell, with extraordinary mechanical and physiological properties, consists of a complex set of proteins, which have a tripartite structure: a central, evolutionarily conserved, domain and two more variable 'arms'. Peptide-analogues of silkmoth chorion protein central domain segments have been synthesized. Laser-Raman and infrared spectroscopic studies suggest the preponderance of antiparallel β-pleated sheet structure for these peptides, both in solution and in the solid state