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The elastic constants of mercury selenide from 4.2 to 300 K have been determined from 10-MHz soundvelocity measurements utilizing the pulse-echo technique. The constants en, en, and cu range from 6.900 X10 11 , 5.105X10 11 , and 2.3073X10 11 dyn/cm 2 , respectively, at 0 K to 5.950X10 11 , 4.307X10 11 , and 2.2015 X10 11 dyn/cm 2 , respectively, at 300 K. The shear modulus C, = 0.899X10 U dyn/cm 2 , compressibility £ el = 1.753X 10~1 2 cm 2 /dyn, and the low-temperature limit of the Debye characteristic temperature O 0 el = 151 K are deduced from values of the elastic constants at 0 K obtained by extrapolation. The reststrahlen frequency as given by the Szigeti relation is 5.12X10 13 Hz. From theoretical and empirical relations, the ionicity of HgSe is estimated to be e*/e=0.7dz0.l. The behavior of the elastic constants and the ionicity of HgSe are compared with the characteristics of other II-VI compounds that have the zinc-blende crystal structure.

An experimental and theoretical study of the electron mobility in the semimetal-semiconductor alloy system Hg& "Cd"Se is reported. for the range of compositions 0.12 & x & 0.68 and at temperatures from 4.2 to 300 K. The samples used in the study are single-crystal specimens grown by the traveling-molten-zone and the Bridgman methods. The mobility data are analyzed in terms of a microscopic theory of electrical conduction appropriate to the alloy system, and the dominant intrinsic and defect-scattering mechanisms are determined.The analysis includes scattering of electrons by longitudinal-optical phopons, longitudinaland transverseacoustical phonons, charged and neutral defects, heavy holes, and the compositional disorder potential of the alloy. It is found that longitudinal-optical-phonon scattering is the dominant mechanism at room temperature for all alloys in the composition range studied. Acoustical-phonon scattering is unimportant at all temperatures and compositions. Scattering associated with the compositional disorder of the alloy increases from 5% of the total scattering at x = 0.12 to 21 k at x = 0.68. Evidence is presented for the presence of four defect species: a donor associated with the HgSe lattice, a donor associated with the CdSe lattice, an acceptor associated with the CdSe lattice, and a stable neutral defect associated with the HgSe lattice.

Purpose -In the light of recent financial scandals, such as Enron, Global Crossing and WorldCom, the purpose of this paper is to use an institutional theory perspective to examine the interactions between the accounting profession, the SEC and the Congress. Design/methodology/approach -The paper takes an institutional perspective of the Sarbanes-Oxley Act and reviews how historical events have led to various institutional developments, which, in turn, have resulted in accountancy changes. Findings -The end result is posited to be an outcome that enhances the legitimacy of the SEC to regulate the accounting profession. At the same time, the accounting profession will emerge from the events able to proclaim that it is improved. Finally, politicians will garner favor from the voters since they have acted to protect the public from financial frauds. Originality/value -Describes how the relationship among the three parties is in reality a highly predictable set of behaviors that will allow all of the participants to demonstrate legitimacy to their external constituents and enable each party to secure enhanced future resources.