Effect of spin-orbit interaction on the metal-insulator transition in doped silicon

Abstract

We show that in disordered metallic systems, spin-orbit interactions lead to the existence of two metallic phases separated in temperature. The low-temperature metallic phase arises from spin-orbit interactions. The crossover temperature is proportional to (Z-Z′)² (Z is the atomic number of the donor and Z′ that of the matrix) and is expected to be observable for donors with large atomic numbers. The presence of two metallic phases implies two mobility edges, existing at different temperatures, and affecting the conductivity when the Fermi energy E _F lies below the mobility edge E _c We thus predict anomalies in the conductivity in this range of concentration, consistent with the measurements of Long and Pepper on Si:Sb.     

Are children more accurate than adults? Spontaneous use of metaphor by children and adults

This study examined an observation in which children outscored adults on a series of test questions, which included unusual items such as, "Do you see with your ears?" We assumed that the adults were treating the questions metaphorically because the literally correct answer was so obvious, an assumption consistent with Grice's theory. In Study 1, we tested this assumption by manipulating pretest and test items so as to suggest, or not suggest, a metaphorical or factual response. In Study 2, we used a similar manipulation involving the order of questions of various sorts and we more directly tested the Gricean hypothesis by giving college students a reason to treat the question literally. The results replicated the previous finding in which college students' scores were lower than those of children, and the condition effects suggested that the college students' performance was due to their responding metaphorically.     

Counselling the counsellors: Support groups in Devon

The establishment of support groups for school and college counsellors in Devon is described. Reference is made to the pressures which led to their creation, to the way the support system has gradually been developed and modified, to the membership, organisation and purpose of the present groups, and to some initial problems and adjustments. Possibilities for future development are suggested.