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The interpretation of data from scanning electron microscopy (SEM) combined with energy dispersive analysis of X-rays (EDAX) is dependent on the size of the excitation volume, the magnitude of which for organic materials such as wood has been little studied. From the analysis of a model system comprised of a thin layer of gold sandwiched between two layers(More)
A mathematical model has been derived for the prediction of the resistance to viscous liquid flow generated by tracheid lumina and various parts of the bordered pit structure. The model also takes into account changes in pit geometry occurring as the pit membrane deflects when a pressure differential is applied across it. Methods for checking whether flow(More)
A number of structural variables influence the conductivity of simple and scalariform perforation plates, and of vessel lumina. Using a previously developed computer model, the effects on conductivity of over 8,000 permutations of different lumen radii, perforation plate angles, perforation plate rim widths, scalariform slit pore heights, and scalariform(More)
A number of workers have noted a marked decrease of wood permeability with increasing specimen length, and to date a model proposed by Bramhall has been used to explain the phenomenon. This describes the effect of random blockages on the permeability of an anisotropic porous medium. However, the model does not allow for the fact that transverse flow may(More)
Existing political economy models rely on inter-industry differences such as factor endowment or factor specificity to explain the politics of trade policy-making. However, this paper finds that a large proportion of variation in U.S. applied tariff rates in fact arises within industry. I offer a theory of trade liberalization that explains how product(More)
Orifice flow and drag theory are found theoretically to be generally inapplicable to axial gas flow through conifer wood under the conditions normally used for gas permeability studies of the material. However, orifice flow theory might be applicable at higher mean pressures or at higher applied pressure drops. Methods of testing this possibility(More)
The effectiveness of psychological services provided remotely, telepsychology, for the management of Posttraumatic Stress Disorder (PTSD) was evaluated. Eleven studies (n = 472 participants) were identified from electronic database searches. Study quality was assessed, with studies characterised by small and underpowered samples. Effect sizes and associated(More)
The different approaches to the use of steady-state gas flow data in the prediction of the steady-state axial permeability of wood to liquids are reviewed. Since these may be shown to have certain theoretical shortcomings, a new predictive method based on a computer analysis is presented. This and previous methods are tested experimentally; apparently, none(More)