7,452 research outputs found

    Following in Your Parents' Footsteps? Empirical Analysis of Matched Parent-Offspring Test Scores

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    In this paper, we explore whether an intergenerational relationship exists between the reading and mathematics test scores, taken at ages 7, 11 and 16, of a cohort of individuals born in 1958 and the equivalent test scores of their offspring measured in 1991. Our results suggest that how the parent performs in reading and mathematics during their childhood is positively related to the corresponding reading and mathematics test scores of their offspring as measured at a similar age. Our findings imply that parental ability in numeracy and literacy as a child is positively associated with the ability in numeracy and literacy of their offspring. With respect to gender, a father´s (mother´s) test score generally has a positive influence on the test scores of their daughter (son)

    REIT Pricing Efficiency; Should Investors Still Be Concerned?

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    This study examines the impact of the REIT boom on the market microstructure of REIT common stocks. We analyze NYSE-traded REITs during the pre-boom period (1992) and the post-boom period (1994), and find significant reductions in bid/ask spreads over the period. We also find that the bid/ask spread differential between REITs and non-REITs has been roughly halved between 1991 and 1994. These reductions provide a direct benefit to REIT investors in terms of reduction in transaction costs and improved liquidity, and suggest that the level of uncertainty on the part of the REIT specialist has been reduced.

    Quantum effects in the diffusion of hydrogen on Ru(0001)

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    An understanding of hydrogen diffusion on metal surfaces is important, not just for its role in heterogeneous catalysis and hydrogen fuel cell technology, but also because it provides model systems where tunneling can be studied under well-defined conditions. Here we report helium spin-echo measurements of the atomic-scale motion of hydrogen on the Ru(0001) surface between 75 and 250 K. Quantum effects are evident at temperatures as high as 200 K, while below 120 K we observe a tunneling-dominated temperature independent jump rate of 1.9×\times109^9 s−1^{-1}, many orders of magnitude faster than previously seen. Quantum transition state theory calculations based on ab initio path-integral simulations reproduce the temperature dependence of the rate at higher temperatures and predict a crossover to tunneling-dominated diffusion at low temperatures, although the tunneling rate is under-estimated, highlighting the need for future experimental and theoretical studies of hydrogen diffusion on well-defined surfaces.Comment: 15 pages, 3 figure

    Magnetic suspension and balance system advanced study, 1989 design

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    The objectives are to experimentally confirm several advanced design concepts on the Magnetic Suspension and Balance Systems (MSBS). The advanced design concepts were identified as potential improvements by Madison Magnetics, Inc. (MMI) during 1984 and 1985 studies of an MSBS utilizing 14 external superconductive coils and a superconductive solenoid in an airplane test model suspended in a wind tunnel. This study confirmed several advanced design concepts on magnetic suspension and balance systems. The 1989 MSBS redesign is based on the results of these experiments. Savings of up to 30 percent in supporting magnet ampere meters and 50 percent in energy stored over the 1985 design were achieved

    Fetal Cortical Transplants in Adult Rats Subjected to Experimental Brain Injury

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    Fetal cortical tissue was injected into injured adult rat brains following concussive fluid percussion (FP) brain injury. Rats subjected to moderate FP injury received E16 cortex transplant injections into lesioned motor cortex 2 days, 1 week, 2 weeks, and 4 weeks post injury. Histological assessment of transplant survival and integration was based upon Nissl staining, glial fibrillary acidic protein (GFAP) immunocytochemistry, and staining for acetylcholinesterase. In addition to histological analysis, the ability of the transplants to attenuate neurological motor deficits associated with concussive FP brain injury was also tested. Three subgroups of rats receiving transplant 1 week, 2 weeks, and 4 weeks post injury Were chosen for evaluation of neurological motor function. Fetal cortical tissue injected into the injury site 4 weeks post injury failed to incorporate with injured host brain, did not affect glial scar formation, and exhibited extensive GFAP immunoreactivity. No improvement in neurological motor function was observed in animals receiving transplants 4 weeks post injury. Conversely, transplants injected 2 days, 1 week, or 2 weeks post injury survived, incorporated with host brain, exhibited little GFAP immunoreactivity, and successfully attenuated glial scarring. However, no significant improvement in motor function was observed at the one week or two week time points. The inability of the transplants to attenuate motor function may indicate inappropriate host/transplant interaction. Our results demonstrate that there exists a temporal window in which fetal cortical transplants can attenuate glial scarring as well as be successfully incorporated into host brains following FP injury

    Identification, Intervention and Collaboration: The Keys To Working Successfully With Mildly Handicapped Students In Rural Areas

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    As the nation\u27s schools are moving toward integration of mild-to-moderate handicapped students within general education classrooms, teachers must gain additional skills and expertise in both diagnosis and remediation

    Neural mechanisms of resistance to peer influence in early adolescence

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    During the shift from a parent-dependent child to a fully autonomous adult, peers take on a significant role in shaping the adolescent’s behaviour. Peer-derived influences are not always positive, however. Here we explore neural correlates of inter-individual differences in the probability of resisting peer influence in early adolescence. Using functional magnetic-resonance imaging (fMRI), we found striking differences between 10-year old children with high and low resistance to peer influence in their brain activity during observation of angry hand-movements and angry facial expressions: compared with subjects with low resistance to peer influence, individuals with high resistance showed a highly coordinated brain activity in neural systems underlying perception of action and decision making. These findings suggest that the probability of resisting peer influence depends on neural interactions during observation of emotion-laden actions
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