This paper focuses on acoustic reflectivity of the ocean bottom, and describes inversion of reflection data from an experiment designed to study the physical properties and structure of the ocean bottom. The formalism of Bayesian inference is reviewed briefly to establish an understanding of the approach for inversion that is in widespread use. A Bayesian inversion of ocean bottom reflection co...

Pulsating auroras are usually observed with ultralow-frequency (ULF) waves in the Pc 3–5 band (period 10–600 s). These thought to result from interactions between energetic electrons and chorus waves, but their relationship ULF remains an open question. In this study, we investigated question by conducting a comparative study on two wave events pulsating near magnetic footprints. Conjugate obse...

Compressional or traumatic asphyxia is a well recognized entity to most forensic pathologists. The vast majority of reported cases have been accidental. The case reported here describes the apparent inflicted compressional asphyxia of a small child. A review of mechanisms and related controversy regarding proposed mechanisms is discussed.

Oil well logs are frequently used to determine the mineralogy and physical properties of potential reservoir rocks, and the nature of the fluids they contain. Recently we reported an exploratory use of neural network ensembles for modeling these records. We showed that ensembles are clearly superior to linear multivariate regression as modeling technique, revealing an underlying nonlinear funct...

The evolution and viscous damping of cosmic magnetic fields in the early universe, is analysed. Using the fact that the fluid, electromagnetic, and shear viscous energy-momentum tensors are all conformally invariant, the evolution is transformed from the expanding universe setting into that in flat spacetime. Particular attention is paid to the evolution of nonlinear Alfvén modes. For a small e...

Contrary to the traditional view, seismic attenuation in Biot's theory of uid-saturated porous media is due to viscous damping of local (not global) pore-uid motion. Since substantial inhomogeneities in uid permeability of porous geological materials are to be expected, the regions of highest local permeability contribute most to the wave energy dissipation while those of lowest permeability do...

There are three general methods that can be used to determine formation velocities from full waveform logs. The first approach is to make use of the data from the entire waveform. This type of velocity analysis is performed either in the frequency domain (I.e. f-k analysis or the two station method) or in the time domain (I.e. velocity spectral analysis). The second approach is to identify the ...

Classical long wavelength approximate solutions to the scattering of acoustic waves by a spherical liquid particle suspended in a liquid (an emulsion) show small but significant differences from full solutions at very low k(c)a (typically k(c)a < 0.01) and above at k(c)a > 0.1, where k(c) is the compressional wavenumber and a the particle radius. These differences may be significant in the cont...

Compressional waves of an earthquake doublet (two events occurring in the South Sandwich Islands on 1 December 1993 and 6 September 2003), recorded at three seismic stations in Russia and Kyrgyzstan and reflected off Earth's inner core boundary, arrived at least from 39 to 70 milliseconds earlier in the 2003 event than in the 1993 event. Such changes indicate that Earth's inner core radius enla...

A numerical method is proposed to simulate the propagation of transient poroelastic waves across 2D heterogeneous media, in the low frequency range. A velocity-stress formulation of Biot’s equations is followed, leading to a first-order system of partial differential equations. This system is splitted in two parts: a propagative one discretized by a fourth-order ADER scheme, and a diffusive one...