Printable, Transparent Force Sensing Resistive Materials for Touchscreen Applications

A transparent, force sensing resistive ink suitable for touchscreen technology is presented, which is capable of detecting both touch location and the applied force. The force sensing behavior is realized by a screen-printed ink layer which consists of pre-formed semi-conductive granules dispersed in an insulating polymer. The granule size is of a comparable dimension to the thickness of the printed layer. Conduction is via the creation of pressure-induced conductive pathways through the layer at the contact point. With increasing force the number of pathways increases and the resistance of the pathways decreases, reducing the resistance through the layer. The electrical behavior was tested with finger-press forces up to 5 N using a load cell and stylus attachment. Optical properties of the touchscreen were assessed using a spectrophotometer to measure the transmitted light over the range of visible wavelengths. Both the force-resistance profiles and the optical properties of the layer are dependent on the granule loading and composition. The structural, optical and force-resistance performance of test devices are discussed.

Quantitative assessment of luminal stirring in the perfused small intestine of the rat

We measured the resistance (RL) to CO absorption that resulted from poor luminal stirring in the constantly perfused rat jejunum. RL or calculated unstirred layer thickness was greater for 30-cm than 10-cm long segments, indicating lack of a uniform thickness of unstirred layer. The possibility that laminar flow existed in the gut was first tested by calculating expected CO absorptions from fluid moving with laminar flow. These values agreed closely with observed absorption rates. Laminar flow also was supported by the observation that CO absorption was independent of perfusate viscosity. Lastly, after sudden addition of phenolsulfonphthalein (PSP) to the perfusate, PSP outflow concentration was similar in tygon tubing (which has laminar flow) and a gut segment of comparable dimension. We conclude that flow in the perfused gut is laminar and that this laminar flow has many implications for studies carried out with the constant-perfusion technique.

Social Mobility and Psychometric Variation in a Group of Oxfordshire Villages

SummaryThe patterns of male social mobility among the contemporary populations of Otmoor are described in terms of both intra- and inter-generational mobility. The social classes are differentiated by IQ and it is shown that sons' IQ is more highly correlated with their class, after their social mobility than before it. In 85 father-son pairs the number of steps sons moved in the social scale is positively related to the magnitude of the difference between their IQ and that of their fathers. However, the relationship between social mobility and IQ appears to be entirely confined to non-locally born subjects and the social mobility among the locals, although of comparable dimension is essentially non-meritocratic. These findings are discussed in relation to the structure of the Otmoor populations and particularly the phenomenon of selective out-migration.