Rebirth of Liquid Crystals for Sensoric Applications: Environmental and Gas Sensors

Films and droplets of liquid crystals may soon become an essential part of sensitive environmental sensors and detectors of volatile organic compounds (VOCs) in the air. In this paper a short overview of recent progress in the area of sensors based on liquid crystals is presented, along with the studies of low molar mass liquid crystals as gas sensors. The detection of VOCs in the air may rely on each of the following effects sequentially observed one after the other: (i) slight changes in orientation and order parameter of liquid crystal, (ii) formation of bubbles on the top of the liquid crystalline droplet, and (iii) complete isotropisation of the liquid crystal. These three stages can be easily monitored by a photo camera and/or optical microscopy. Detection limits corresponding to the first stage are typically lower by a factor of at least 3–6 than detection limits corresponding to isotropisation. The qualitative model taking into account the reorientation of liquid crystals is presented to account for the observed changes

Child and adolescent differences in economy at various speeds across a two-year time period

Economy of movement is defmed as the mass related aerobic demand (V02 mL·kg-l·min-l) or energy expenditure required to run or walk at a given submaximal speed (Morgan, 2000). It has been well established that children have a lower economy compared to adults (Rowland and Green, 1988; Rowland et al., 1987; Unnithan and Eston, 1990). This means that at any given walking or running speed, children exhibit a higher weight relative V02compared to that of an adult. The difference in economy between children and adults is thought to be due to differences in stride frequency (SF), leg length, body-surface-area to mass ratio (BSA:M), body mass index (BMI), and ventilatory efficiency (Rowland et al., 1987; Rowland and Green, 1988; Unnithan and Eston, 1990)

A constant-quality price index for resale public housing flats in Singapore

10.1080/0042098032000146858Urban Studies40132705-272

Estimation of Depreciation for Single-Family Appraisals

Methods for the estimation of depreciation within the cost approach to appraisal of single-family residential property have been the focus of very few empirical studies. The purpose of this study is to generate empirical evidence related to one such method, specifically the age-life method. Within the context of a hedonic price model, functional form of the model and the design of the age variable are chosen so that we can test for alternative paths of depreciation with just one model. The alternative paths can be concave, convex or straight-line. Contrary to the evidence presented in several previous studies, the empirical evidence presented in this paper supports a path of depreciation for single-family houses that is concave (i.e., initially less rapid than straight-line). Of the standard paths of depreciation often suggested, the reverse sum of the years digits path most closely approximates the path indicated as appropriate by this study, particularly in the early years of the life of a house. If appraisers are looking for an approximation of the path of depreciation for single-family residences, it would appear that the reverse sum of the years digits path is much more appropriate than the straight-line path that is often assumed. Copyright American Real Estate and Urban Economics Association.