An alternative speci¢cation for the trend component of crop yield growth is developed and applied to maize yield data for Zimbabwe's large-scale farming sector. This accounts for permanent regime shifts as new technologies are discovered but allows gradual absorption as adoption follows a di¡usion path. Econometric methods are used to estimate the timing and importance of innovations, as well a...

Error di usion ordered dither and patterning are well known digital halftoning tech niques each with its advantages and disadvantages Error di usion is known for correlated artifacts looking like zebra stripes Images produced by ordered dither and patterning su er from arti cial contours in slowly varying regions of pictures Use of ordered matrices by both ordered dither and patterning results ...

Tritium behavior in plasma-facing components (PFCs) of future tokamak reactors such as ITER is an essential factor in evaluating and choosing the ideal plasma-facing materials (PFMs). One important parameter that in ̄uences tritium buildup and release in candidate materials is the e€ect of material porosity on tritium di€usion and retention. Di€usion in porous materials, for example, consists of...

A three-dimensional model for release and di usion of glutamate in the synaptic cleft was developed and solved analytically. The model consists of a source function describing transmitter release from the vesicle and a di usion function describing the spread of transmitter in the cleft. Concentration pro les of transmitter at the postsynaptic side were calculated for di erent transmitter concen...

|The error di usion algorithm for digital halftoning is equivalent in form to a noise-shaping feedback coder, a class of delta-sigma modulator. The white noise assumption of the quantizer error is known to be false; in fact, the quantizer error is seen to be highly correlated with the input image. To account for this correlation, we use a gain model for the quantizer. This model accurately pred...

This appendix shows simulation results using URDME and MesoRD for a simple di↵usion problem. This problem illustrates the advantage of unstructured meshes: the ability to resolve processes on curved surfaces without causing a unnecessarily fine discretization. We also evaluate the accuracy of the software on a non-trivial reaction-di↵usion system by simulating the example of Min oscillations pr...

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...

The Yale stellar evolution code has been modi ed to include the combined e ects of di usion and rotational mixing on 1 H, 4 He and the trace elements 3 He, 6 Li, 7 Li, and 9 Be. The interaction between rotational mixing and di usion is studied by calculating a number of calibrated solar models. The rotational mixing inhibits the di usion in the outer parts of the models, leading to a decrease i...