Of the *240 9 10 mol year of biogenic silica (bSi) produced by diatoms and other silicifying organisms, only roughly 3%–4% escapes dissolution to be permanently buried. At the global scale, how, where and why bSi is preserved in sediment is not well understood. To help address this, I compile 6245 porewater dissolved Si concentrations from 453 sediment cores, to derive the concentration gradien...

This paper examines thermoacoustic effects on the propagation of non-planar sound in a circular duct subjected to an axial temperature gradient. Of particular concern are thermoviscous diffusive effects, which taken into account by boundary-layer approximation framework linear theory. For disturbances expanded Fourier and Fourier–Bessel series azimuthal radial directions, respectively, pressure...

The rate of oxygen consumption of isolated, Langendorff-circulated, saline-perfused hearts of guinea pigs, rats, and rabbits was measured using the classical Fick Principle method. The heart was suspended in a glass chamber the oxygen partial pressure, PO2, of which could be varied. The measured rate of oxygen consumption was found to vary inversely with the ambient (heart chamber) PO2. This re...

We study the contribution of advection by thermal velocity fluctuations to the effective diffusion coefficient in a mixture of two identical fluids. The steady-state diffusive flux in a finite system subject to a concentration gradient is enhanced because of long-range correlations between concentration fluctuations and fluctuations of the velocity parallel to the concentration gradient. The en...

The textbook thermophoretic force which acts on a body in a fluid is proportional to the local temperature gradient. The same is expected to hold for the macroscopic drift behavior of a diffusive cluster or molecule physisorbed on a solid surface. The question we explore here is whether that is still valid on a 2D membrane such as graphene at short sheet length. By means of a nonequilibrium mol...

We are interested in the effects of diffusivity and chemotaxis on the competition of several species for a limited resource. Diffusivity of cells is also called motility in some engineering literature. Chemotaxis is the oriented movement of cells in response to the concentration gradient of chemical substances in their environment. It is ”anti-diffusion”. It was observed experimentally that mot...

In this paper, we prove the wellposedness of classical solutions for equation, deduced in [23]. It represents a reaction-diffusion model which spatial structure is maintained by means diffusive mechanism more general than Fickian diffusion. This generalized diffusion takes into account gradient (or energy) necessary to maintain pattern even single diffusing species.