Is It Daxing? The Effect of Learning Formats on Preschoolers' Acquisition of Novel Dynamic Relations

This study investigated whether generic stimuli improve children’s ability to acquire and transfer novel dynamic relations. Three-year-olds and four-year-olds learned a novel dynamic relation (an object disappearing), which was arbitrarily termed “daxing.” Half of the participants learned with generic stimuli and half learned with concrete stimuli. Then each participant identified novel dynamic relations as either “daxing” or “not daxing.” Results revealed both developmental and learning format trends. Four-year-olds in both conditions were more adept than three-year-olds at learning and transferring the relation. Learning formats did not significantly affect three-year-olds’ ability to transfer; however, within the four-year-olds, participants who learned with generic formats transferred significantly better than those who learned with concrete formats. Because generic stimuli are perceptually simpler and less distracting than rich stimuli, four-year-olds in the generic condition may have been better able to focus on the relation and, therefore, better able to recognize it in new contexts. These findings add to understanding of the acquisition of novel relations, demonstrating that generic learning formats, as compared to concrete formats, may lend young children an advantage not only for static, perceptual relations, but also for dynamic relations.No embarg

The 2+1 Kepler Problem and Its Quantization

We study a system of two pointlike particles coupled to three dimensional Einstein gravity. The reduced phase space can be considered as a deformed version of the phase space of two special-relativistic point particles in the centre of mass frame. When the system is quantized, we find some possibly general effects of quantum gravity, such as a minimal distances and a foaminess of the spacetime at the order of the Planck length. We also obtain a quantization of geometry, which restricts the possible asymptotic geometries of the universe.Comment: 59 pages, LaTeX2e, 9 eps figure

Hamiltonian solutions of the 3-body problem in (2+1)-gravity

We present a full study of the 3-body problem in gravity in flat (2+1)-dimensional space-time, and in the nonrelativistic limit of small velocities. We provide an explicit form of the ADM Hamiltonian in a regular coordinate system and we set up all the ingredients for canonical quantization. We emphasize the role of a U(2) symmetry under which the Hamiltonian is invariant and which should generalize to a U(N-1) symmetry for N bodies. This symmetry seems to stem from a braid group structure in the operations of looping of particles around each other, and guarantees the single-valuedness of the Hamiltonian. Its role for the construction of single-valued energy eigenfunctions is also discussed.Comment: 25 pages, no figure. v2: some calculation details removed to make the paper more concise (see v1 for the longer version), minor correction in a formula in the section on quantization, references added; results and conclusions unchange

Paper Session II-C - Optical Alignment Measurements of Space Shuttle Tiles

The Space Shuttles are serviced and maintained by the Lockheed Space Operations Company (LSOC) at the Kennedy Space Center in Florida. The tiles which act as a heat shield during Shuttle re-entry into the earth\u27s atmosphere, are a major part of the Shuttle servicing efforts. One very tedious and labor intensive task is the alignment measurement of these tiles. Alignment measurements include measuring the gaps, or separation between two adjacent tiles, and measuring the steps, or the height differences between adjacent tiles. Traditional methods of measurement required two mechanical tools to separately measure steps and gaps. Plastic feeler gauges were used for gap measurements and dial-indicator trammel tools were used to measure steps. The Lockheed Research And Development Division (R&DD) in Palo Alto, CA developed and built the hand-held optical tool, the Lockheed Laser Tool (LLT), that is currently being used to measure tile steps and gaps. The LLT measures both steps and gaps simultaneously, replacing both mechanical tools. Integration of the LLT into the Shuttle servicing environment and the formal certification and acceptance of its use was an important milestone for state-ofthe- art technology being utilized to improve and maintain Shuttle processing flow. This was an iterative process during a six month period in 1988. Direct feedback from Shuttle operations/engineering helped refine the user-interface and became a critical contribution to the success of the program