The dynamic effective mass density and bulk modulus of an inhomogeneous medium at low frequency limit are discussed. Random configurations in a variety of two-dimensional physical contexts are considered. In each case, effective dynamic mass density and bulk modulus are calculated based on eigenmode matching theory. The results agree with those provided by Martin et al. [J. Acoust. Soc. Am. 128...

The structural symmetry and molecular separation in water and ice remain uncertain. We present herewith a solution to unifying the density, the structure order and symmetry, the size (H-O length dH), and the separation (d(OO) = d(L) + d(H) or the O:H length d(L)) of molecules packing in water and ice in terms of statistic mean. This solution reconciles: i) the d(L) and the d(H) symmetrization o...

Current experiments on atomic gases in highly anisotropic traps present the opportunity to study in detail the low temperature phases of two-dimensional inhomogeneous systems. Although, in an ideal gas, the trapping potential favors Bose-Einstein condensation at finite temperature, interactions tend to destabilize the condensate, leading to a superfluid Kosterlitz-Thouless-Berezinskii phase wit...

We use weighted mean and median statistics techniques to combine individual estimates of ΩM0, the present mean mass density in non-relativistic matter, and determine the observed values and ranges of ΩM0 from different combinations of data. The derived weighted mean ΩM0 values are not good representatives of the individual measurements, under the assumptions of Gaussianity and negligible correl...

Recent work by Tajmar and de Matos predicts a greatly enhanced gravitomagnetic field is measurable in the vicinity of a rotating superconductor. They predict that the associated frame dragging is measurable when the density of Cooper pairs is sufficiently large relative to the mass density. Experimental measurements with superconducting lead and niobium samples reported by the same group suppor...

The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment, and a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sedime...

The problem of calibrating parametric sonar systems at low difference frequencies used in backscattering applications is addressed. A particular parametric sonar is considered: the Simrad TOPAS PS18 Parametric Sub-bottom Profiler. This generates difference-frequency signals in the band 0.5-6 kHz. A standard target is specified according to optimization conditions based on maximizing the target ...

We examine the spectrum of gravitational radiation emitted by a network of cosmic strings, with emphasis on the observational constraints and the opportunities for detection. The analysis improves over past work, as we use a phenomenological model for the radiation spectrum emitted by a cosmic string loop. This model attempts to include the effect of the gravitational back-reaction on the radia...

We discuss correlation properties of a general mass density field introducing a classification of structures based on their complexity. Standard cosmological models for primordial mass fluctuations are characterized by a sort of large-scale stochastic order, that we call super-homogeneity to highlight the fact that mass fluctuations increase as a function of scale in the slowest possible way fo...

The positive mass theorem of general relativity to be addressed here states that the total mass of an isolated gravitational system (viewed from spatial infinity, known as the ADM mass) must be non-negative if its local mass density is non-negative everywhere, and in fact the mass is strictly positive unless the space-time is flat. In this essay we are only concerned with the first part of this...