An anisotropic electron spin resonance spectrum was observed in three natural Type Ib diamonds. The diamonds which exhibit the spectrum also show the spectrum from substitutional nitrogen donors previously observed by others. The spectrum consists of three anisotropic groups of lines. The spectrum is interpreted in terms of a model in which each defect center is characterized by a spin Hamiltonian of the form H=βS·g·H+A·I·S, where S = ½ and I = 1, and in which the tensors g and A each have one component g1 and A1 oriented in a 〈110〉 direction. The spin-one nucleus is believed to be nitrogen. The principal components of g and A have the values g1 = 2.0031±0.0003, g2 = 2.0019±0.0003, g3 = 2.0025±0.0003, A1 = 5.303±0.005×10−4 cm−1, A2 = 7.164±0.005×10−4 cm−1, and A3 = 5.293±0.005×10−4 cm−1. The components g2 and A2 make angles Ψ = 45.2°±0.3° and α = 22.4°±0.1°, respectively, with 〈110〉 directions. The theoretical angular dependencies of the spectra when the magnetic field H is rotated in {100}, {110}, and {111} crystalline planes were calculated on the basis of the above model and are in excellent agreement with the experimentally observed angular behaviors.

Equations are derived giving the period of rocking oscillatory motion of various bodies when placed on a flat horizontal surface, displaced from equilibrium, and released. The bodies include a sphere and a circular disk with a flat surface, a circular disk with a circular hole, and elliptical disks with circular and elliptical holes. A technique that can be used in an undergraduate mechanics laboratory is described for determining the period of rocking oscillatory motion. The technique consists of measuring the frequency with which electrical continuity is completed when a metallic body instantaneously makes contact with two conducting plates as it undergoes rocking oscillatory motion. The timing is accomplished with digital electronics.

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Combinations of tensile testing and bending stress-induced tests were conducted on different diameter optical fibers, with different protective coatings, manufactured by different fiber vendors. Various types of stress-aging effects were studied. The work was done to gain an understanding of mechanical strength variability of optical fiber and the effects of environment as they relate to potential applications in optical firing systems designs and enhanced surveillance campaign activity.

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