The problem of causality in an indeterministic science

A differentiation between the principles of causality and strict determinism is suggested, the principle of strict determinism being considered to be incompatible with current scientific theory, while the principle of causality is supported by all contemporary scientific knowledge. In this paper the importance of the principle of causality in indeterministic causal theories is discussed, non-relativistic quantum mechanics being considered in detail. Indeterministic causality and its relation to relativistic quantum theory is also discussed.     

The geometrical and vibrational properties of the Rh(111) surface

Low-energy electron diffraction (LEED) data have been used to characterize the clean Rh(111) surface. The surface geometry, the degree of surface relaxation, and the Debye temperature have been determined. In the Debye temperature measurement, specular LEED beam intensities were monitored as a function of temperature over a range of electron energies from approximately 30 to 1000 eV. It was found that the bulk Debye temperature is 380 ± 23 K, and the normal component of the Debye temperature at the lowest electron energy used is 197 ± 12 K. The Rh(111) surface relaxation has been determined both by a convolution-transform analysis and by dynamical calculations. Within experimental error, neither expansion nor contraction of the topmost layer has been detected. The results of the convolution-transform analysis of specular beams at two angles of incidence and of a nonspecular beam at normal incidence suggest an expansion of the topmost layer of 3 ± 5% of the bulk layer spacing. In agreement with this, comparisons between the results of the dynamical calculation and experimental data for five nonspecular beams at normal incidence suggest that the surface layer relaxes by 0 ± 5%. In addition, the dynamical calculations indicate that the topmost layer maintains an fcc structure.     

On the use of incomplete constitutive information in thermoelasticity

The extent to which non-linear thermoelastic constitutive data may be determined by controllable states is delineated, and thermomechanical states that may be analyzed completely with such incomplete data are catalogued. These include non-homogeneous finite deformations coupled with quite general temperature fields in plane, cylindrical and spherical geometries. Two problems involving the states are worked out as examples.This research was supported by the U.S. National Science Foundation Grant GK-37367 to The University of Texas at Austin.     

Anharmonicity in polyatomic molecules: The problem of phase coincidence and applications to the CH-stretching overtone spectrum of benzene

A previous analysis of the first six members of the CH-stretching overtone spectrum of benzene in terms of local oscillators is reexamined (1). The importance of the choice of relative phases in the transformation from normal modes to local modes is elucidated. The theory is recast in a form more consistent with the limitations indicated by this analysis. The frequencies of all eight members of the CH-stretching overtone spectrum of benzene are calculated on this basis and excellent agreement with experiment is obtained.     

Gas phase thermolysis of cyanomethyl t-butyl sulfide and cyanomethyl t-butyl ether

The pyrolyses of cyanomethyl t-butyl sulfide and its oxygen homologue have been studied in a stirred-flow system over the temperature range 490–540°C and pressures between 5 and 14 Torr. In both cases, isobutene is formed as product in over 97% yield. Hydrogen sulfide is obtained in about half the amount of isobutene in the pyrolysis of the sulfide. Hydrogen cyanide is formed in the pyrolysis of the ether. The first-order rate coefficients for the consumption of the reactants followed the Arrhenius equations Cyanomethyl t-butyl sulfide: Cyanomethyl t-butyl ether: A molecular mechanism involving polar four-centered cyclic transition states is proposed for both reactions, with the CN group stabilizing the partial negative charge developed at the S and O atoms.     

On Witten's proof of the positive energy theorem

This paper gives a mathematically rigorous proof of the positive energy theorem using spinors. This completes and simplifies the original argument presented by Edward Witten. We clarify the geometric aspects of this argument and prove the necessary analytic theorems concerning the relevant Dirac operator.Supported in part by the National Science Foundation under Grant PHY79-16812Junior Fellow, Harvard University Society of Fellows     

Interpretation of apparent surface texture observed in the Mössbauer spectra of some57Co-doped ferromagnetic metals

Cobalt-57-doped Fe, Co, and Ni sheets were studied by Mössbauer spectroscopy. The spectra indicated that the preferred direction of the effective magnetic field in Fe and Ni was parallel to the surface. With Co only little preference was observed. The observations are quantitatively explained by assuming that the closure domains may only show parallel to the local easy direction of magnetization, but otherwise tend to be as perpendicular to the normal vector of the surface as possible.     

InP growth and properties

Bulk polycrystalline InP is synthesized from the elements via a gradient freeze process. Hall data for a typical boule are N_d-N_a= 4.7 × 10¹⁵/cm³ and Μ77 = 28,000 cm²/V-sec. Photoluminescence data indicate that zinc is present as an acceptor impurity in the polycrystalline InP and in nominally undoped LEC single crystals grown using the synthesized InP as charge material. A series of doping experiments have determined the effective segregation coefficient to be 1.6 × 10⁻³ for Fe in InP. Semi-insulating InP crystals with resistivity > 10⁷ ohm—cm have been grown consistently from melts doped with 150 ppm Fe.     

The determination of cadmium in geological materials by flameless atomic absorption spectrometry

The use of graphite-furnace atomic absorption spectrometry for the determination of cadmium in rocks and sediments by direct atomization from the solid state is described. At the 10–1000 p.p.b. level, the relative standard deviation is ± 10–20 %. Samples were ground to 100 mesh and, if necessary, 325 mesh before analysis. Two resonance lines were employed: 228.8 nm for less than 5 p.p.m. cadmium and 326.1 nm for levels above 5 p.p.m. Instrumental parameters were optimized to produce maximum peak heights. Results are given for a series of standard rocks and for stream sediment samples.