Abstract. The nine adiabatic elastic stiffness constants of synthetic single-crystal fayalite, FezSiO4, were measured as functions of pressure (range, 0 to 1.0 GPa) and temperature (range, 0 to 40 ~ C) using the pulse superposition ultrasonic method. Summary calculated results for a dense fayalite polycrystalline aggregate, based on the HS average of our single-crystal data, are as follows: Vp-6.67km/s; V~ = 3.39 km/s; K = 127.9 GPa; # = 50.3 GPa; (~K/SP)r = 5.2; (8 #/SP)r = 1.5;(~ K/~ T)e = --0.030 GPa/K; and, (~#/8 T)p = -0.013 GPa/K (the pressure and temperature data are referred to 25~ and 1 atm, respectively). Accuracy of the single-crystal results was maintained by numerous cross and redundancy checks.Compared to the single-crystal elastic properties of forsterite, MgzSiO4, the fayalite stiffness constants, as well as their pressure derivatives, are lower for each of the on-diagonal (Cij for which i=j) values, and generally higher for the off-diagonal (Cij for which i*j) data. As a result, the bulk moduli (K) and dK/dP for forsterite and fayalite are very similar, but the rigidity modulus (#) and d#/dP for polycrystalline fayalite are much lower than their forsterite counterparts. The bulk compression properties derived from this study are very consistent with the static-compression x-ray results of Yagi et al. (1975). The temperature dependence of the bulk modulus of fayalite is somewhat greater (in a negative sense) than that of forsterite. The rigidity dependencies are almost equivalent. Over the temperature range relevant to this study, the elastic property results are generally consistent with the data of Sumino (1978), which were obtained using the RPR technique. However, some of the compressional modes are clearly discrepant. The elastic constants of fayalite appear to be less consistent with a theoretical HCP model (Leibfried 1955) than forsterite, reflecting the more covalent character of the Fe-O bonding in the former.

Males typically surpass females in spatial performance, an outcome that may be linked to testosterone and estrogen. The authors (a) review physiological mechanisms, developmental periods, and past empirical work relevant to sex steroids' effects on human spatial performance and (b) report an experimental study of the role of actively circulating sex steroids in adolescents being treated for delayed puberty (N = 55; mean age = 13.70 years). Sex steroids (simulating early, middle, and late puberty) and placebos were given alternately over 21 months and spatial tests were given every 3 months. Spatial performance showed traditional sex differences but did not vary with levels of actively circulating sex steroids.

Male and female adolescents who differed in physical attractiveness (PA) were also expected to differ in peer and parent relations, classroom behaviors, and self-perceptions, with adolescents higher in PA expected to score more favorably than those lower in PA. To test these expectations, sixth graders from the Pennsylvania Early Adolescent Transitions Study were longitudinally assessed at the beginning, middle, and end of sixth grade. Across time, adolescents who saw themselves as competent were rated similarly by their teachers and had better peer and parent relations than was the case with the adolescents who saw themselves as less competent. As expected, PA was associated with these differences. Within and across time, adolescents higher in PA tended to have more favorable ratings than did adolescents lower in PA. The stimulus information value of PA for cuing a stereotype regarding attractiveness is discussed.

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