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Microfibril deposition i n most plant cells i s influenced by cortical microtubules. Thus, cortical microtubules are templates that provide spatial information to the cell wall. How cortical microtubules acquire their spatial information and are positioned is unknown. There are indications that plant cells respond to mechanical stresses by using microtubules as sensing elements. Regenerating protoplasts from tobacco (Nicotiana tabacum) were used to determine whether cells can be induced t o expand in a preferential direction in response to an externally applied unidirectional force. Additionally, an anti-microtubule herbicide was used t o investigate the role of microtubules in the response to this force. Protoplasts were embedded i n agarose, briefly centrifuged at 28 to 34g, and either cultured or immediately prepared for immunolocalization of their microtubules. The microtubules within many centrifuged protoplasts were found t o be oriented parallel t o the centrifugal force vector. Most protoplasts elongated with a preferential axis that was oriented 60 t o 90" t o the applied force vector. Protoplasts treated transiently with the reversible microtubule-disrupting agent amiprophos-methyl (applied before and during centrifugation) elongated but without a preferential growth axis. These results indicate that brief biophysical forces may influence the alignment of cortical microtubules and that microtubules themselves act as biophysical responding elements.

This study addresses factors commonly examined in the research concerning adoption and use of e-business and e-commerce information technology (EEIT) by small and medium enterprises (SMEs). The primary objectives are to determine: 1) what barriers and incentives SMEs perceive in adopting EEIT; 2) how the level of adoption of EEIT influences perceptions of incentives and barriers; and 3) whether results vary depending on demographic characteristics of size, geographic market scope, or industry sector. This paper also examines how homogenous SMEs’ perceptions are in their consideration of EEIT adoption factors. Data were collected from 290 U.S. SMEs. The findings revealed that among 25 factors identified in the research literature as incentives or barriers to adoption of EEIT by SMEs, only 16 factors were significant in the population studied, 12 as incentives and four as barriers. Factors were perceived differently as incentives or barriers by adopters, intended adopters, and non-adopters of EEIT. A number of differences were found among SMEs based on demographic characteristics, particularly size and industry-sector.

A numerical model is developed to study the flow of a thermoset resin parallel to a unidirectional, heated fiber array, where the resin viscosity varies with temperature. Steady, incompressible flow is assumed when solving the momentum equation for the velocity parallel to the fiber tow. Resin temperatures are determined by applying a finite differencing scheme to the convective energy equation. An iterative approach is used to update the velocity, temperature, and viscosity in the flow direction. The resulting nonisothermal flow profiles are 'plug-like" with significant increases in the velocities near the fibers. Comparisons of average total flow times for isothermal and nonisothermal flows indicate that, for an epoxy resin at an initial 250C and the fibers heated to 100°C. the fill time is equivalent to the isothermal case with the resin held at a constant 50°C.

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