A summation principle for perceived intensity of odors was investigated for mixtures of dimethyl disulphide, hydrogen sulphide, and pyridine. Mixtures were made by forming all possible pairs of these 3 compounds each appearing at S levels of perceived intensity. Perceived intensity of the individual odorants as well as the mixtures were scaled with a magnitude-estimation procedure. Results clearly showed that theoretical values calculated according to a vector model of odor interaction were in good agreement with the empirically obtained perceived intensity values for all mixtures. For components (individual odorants) equal in perceived intensity, a direct proportionality between perceived intensity of the mixture and the arithmetic sum of the perceived intensity of components was found. This result, which conforms to a special case of the vector model, is in agreement with findings reported earlier. The vector model also has practical relevance for problems of odorous air pollution.
Lines of different lengths were offered to subjects. One half of ten lines were presented horizontally; the longer and shorter part of a line that the subjects have to Droduce SO that the Dartition feels hamothe other vertically. It was found that two groups of subjects, graduate and undergraduate psychologists and art students at the average produced a ratio close to the ratio ,,ious pleasant. The presknt study therefore is another contribution to the controversy Of the -the "golden section", which is a controversy in aesthetics.Godkewitsch, M. (1974). The "golden section": An artifact of stimulus range and measure of preference. Am.
The additive degradation model assumes that the measured projection data is the sum of scatter and primary distributions. Within this framework, the scatter projection can be estimated by convolving the primary projection with a point or line raponse function normalized to primary. The convolution scatter-subtraction was formulated to overcome the fact that the primary projection is not available for Such estimation. This hypothesis assumes that accurate scatter projection data C M be obtained by convolving the measured projection (which is readily available) with scatter response function normalized to primary PIUS scattered events. The aims of this work are (i) to investigate the truth of this assumption and (ii) to delineate its validity domain.We have found that the assumption is valid if relatively large matrices are used to acmmmodare all the values of the Scatter response functions. This requirement is paticularly critical when imaging large objects using large discrimination windows. The validity of the assumption rapidly deteriorates as the measured projections change from smooth to diffuse distributions. At this point, the shapes of scauer response functions become important, We concluded that a better understanding of the current image restoration techniques by convolution needs a new degradation model with formulation which is not restricted to the measured projection data.
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