This investigation concerns the effect of certain physical factors-viscosity, dielectric constant, ionic strength, and temperature of the medium-on the reaction of hydrogen peroxide and ferrocytochrome c in the presence of the enzyme horse-radish peroxidase. From study of the effects of viscosity and dielectric constant, it was concluded that the reaction between the secondary complex of hydrogen peroxide and enzyme on the one hand and ferrocytochrome c on the other is controlled by diffusion in media of high viscosity and by electrostatic effects at low viscosities. With respect to ionic strength, the data at pH 4.7 indicated a dipole-dipole interreaction. The temperature dependence of the over-all reaction had a Q(10) of 1.25.
Absfrucf -During August 1991, the Naval Research Laboratory conducted high-frequency shallow water acoustic scattering experiments in the Gulf of Mexico near Panama City, Florida. The acoustic measurements included surface and bottom reverberation, surface and bottom forward scattering, and direct path propagatlon. The results reported here are confined to the direct and bottom forward reflected paths and include the statktical characteristics of three signals; namely, the dlrect, the bottom reflected, and the direct plus the bottom reflected. Representative envelopes wlll be presented that illustrate the complexity of the shallow water environment Statistics, including the means, variances, and probability distributions for each signal, are presented to discern any differences that can be exploited In the detection process. The frequency range covered during the experiment was from 20 to 180 kHz. The supportlng environmental measurements included sound speed profiles, currents, wave heights, and bottom samples.
Several derivations of the wave equation in an inhomogeneous medium appear in the literature. A term ∇p1⋅∇lnρ0 is found in all of them. Inhomogeneities in the sea are due to both gravity and other effects. The reference state characterized by ρ0(xyz) gives rise to two different limits, one due to gravity alone and the other due to inhomogeneities ignoring gravity. Both lead to the same form of the wave equation, but different arguments are required to demonstrate that ∇p1⋅∇lnρ0 can be ignored. A seldom cited paper by Bergmann [J. Acoust. Soc. Am. 17, 329–333 (1946)] is used.
When designing signal processors to discriminate against underwater sound background noise and scattering, it is important to know the statistics of the unwanted signal disturbances. A study was undertaken for the Naval Research Laboratory, Stennis Space Center, Mississippi to review the literature reporting on a number of bottom scattering experiments that were conducted during the past 15–20 years. The scope of the investigation is limited to high frequencies (10 to 200 kHz) and shallow water of depths less than 100 m. Many of these tests were performed by the Naval Research Laboratory, Stennis Space Center; the Applied Research Laboratories, University of Texas at Austin; and the Applied Physics Laboratory, University of Washington. Other experiments reviewed were performed by Thomson-Sintra ASM, France and by the University of Wisconsin. Each experiment will be briefly described, and the statistical results discussed and summarized for various parameters, such as frequency, beamwidth, pulse length, grazing angle, range, and environmental factors. The statistic that was primarily examined was the probability of false alarm. The PFAs were found to follow a number of probability distribution functions including Gaussian, Rayleigh, log-normal, etc. The PFAs were quantified to systematically determine any trends with the parameters.
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