Oxygen delivery to the tissues is crucial to survival but our understanding of the processes involved in the transport of oxygen from blood to tissue is incomplete. The aim of the present work is to illustrate a long-standing paradox regarding such transport by reporting new state-of-the-art measurements and by analyzing the results in several ways, thereby exploring possible resolutions of the...

Why is Africa poor? Conversely, what has sustained the immense economic growth we have seen in the U.K., the U.S., and other developed countries over the last couple of centuries? While there is no single answer to these questions, technical change looms large among possible explanations. From Solow’s seminal work on growth theory to the “new growth economics”, technical change is the engine of...

The leaching reaction kinetics of weathered crust elution-deposited rare earth with mixed ammonium salts was studied. The in uence of concentration of reagents and particle size of ore on leaching rate was investigated. The results showed that the di usion process and leaching rate could be improved by increasing reagents concentration and decreasing leaching owing rate and particle size. The l...

A model for long range di usion reaction on population dynamics has been considered, and conditions for the existence and uniqueness of solutions to the model in L p;q norms has been obtained.

The classical Petrov-Galerkin approach to Black Box multigrid for nonsymmetric problems due to Dendy is combined with the recent factor-three-coarsening Black Box algorithm due to Dendy and Moulton, along with a powerful symmetric line Gauss-Seidel smoother, resulting in an e cient and robust multigrid solver. Focusing on the convectiondi usion operator, the algorithm is tested and shown to ach...

For a large class of irregular grid applications, the structure of the mesh changes from one phase of the computation to the next. Eventually, as the graph evolves, the adapted mesh has to be repartitioned to ensure good load balance. If this new graph is partitioned from scratch, it will lead to an excessive migration of data among processors. In this paper, we present two new schemes for comp...

Di¡usion tensor imaging studies in schizophrenia have demonstratedlowerdi¡usion anisotropy withinwhitematter thatprovides information about brain white matter integrity.We have examined whether whitematter is abnormal in ¢rst-episode schizophrenia by using di¡usion tensor imaging. Twenty-one schizophrenic patients and healthy controls underwent di¡usion tensor imaging scans that analyzed by usi...

in this paper, we propose an algorithm for numerical solving an inverse non-linear diusion problem. in additional, the least-squares method is adopted tond the solution. to regularize the resultant ill-conditioned linear system ofequations, we apply the tikhonov regularization method to obtain the stablenumerical approximation to the solution. some numerical experiments con-rm the utility of...

The forward di¤usion equation for gene frequency dynamics is solved subject to the condition that the total probability is conserved at all times. This can lead to solutions developing singular spikes (Dirac delta functions) at the gene frequencies 0 and 1. When such spikes appear in solutions they signal gene loss or gene …xation, with the “weight”associated with the spikes corresponding to th...

The e ect of arti cial di usion on discrete shock structures is examined for a family of schemes which includes scalar di usion, convective upwind and split pressure (CUSP) schemes, and upwind schemes with characteristic splitting. The analysis leads to conditions on the di usive ux such that stationary discrete shocks can contain a single interior point. The simplest formulation which meets th...