ABSTRACT
This paper is concerned with the potential for the detection and location of an artery containing a partial blockage by exploiting the space-time properties of the shear wave field in the surrounding elastic soft tissue. As a demonstration of feasibility, an array of piezoelectric film vibration sensors is placed on the free surface of a urethane mold that contains a surgical tube. Inside the surgical tube is a nylon constriction that inhibits the water flowing through the tube. A turbulent field develops in and downstream from the blockage, creating a randomly fluctuating pressure on the inner wall of the tube. This force produces shear and compressional wave energy in the urethane. After the array is used to sample the dominant shear wave space-time energy field at low frequencies, a nearfield (i.e., focused) beamforming process then images the energy distribution in the three-dimensional solid. Experiments and numerical simulations are included to demonstrate the potential of this noninvasive procedure for the early identification of vascular blockages-the typical precursor of serious arterial disease in the human heart.
Subject(s)
Coronary Disease/diagnosis , Coronary Vessels/physiopathology , Models, Anatomic , Models, Cardiovascular , Phonocardiography/methods , Amplifiers, Electronic , Biophysical Phenomena , Biophysics , Blood Flow Velocity , Color , Coronary Disease/physiopathology , Feasibility Studies , Humans , Mathematics , Phonocardiography/instrumentation , Phonocardiography/statistics & numerical data , Time Factors , UrethaneSubject(s)
Data Display , Task Performance and Analysis , Adolescent , Adult , Age Factors , Humans , Memory, Short-Term , Middle AgedABSTRACT
Human error in the transmission of coded information can be reduced by careful choice of vocabulary, using empirical evidence already available.
Subject(s)
Auditory Perception , Cognition Disorders , Form Perception , Memory, Short-Term , Acoustic Stimulation , Adult , Female , Humans , Information Theory , Male , Middle Aged , Speech , VocabularyABSTRACT
Two experiments are reported in which the objective was to achieve minimal confusability among 14 colours required for the new lower-value range of decimal stamps. The main conclusion is that aesthetic considerations are largely incompatible with the criteria required to meet this objective. A symmetrically structured range of seven bright hues, each used at two levels of saturation, was found to have some advantages over an alternative unsymmetrical range which included more pleasing colours. This was mainly because the latter included greater variation along the brightness dimension, which produced large errors in recognition of darker hues. It could also have resulted from the greater nameability of colours made possible by combining hue and saturation cues systematically. The findings emphasise that absolute confusability of colour displays cannot be assessed reliably by viewing stimuli side-by-side, because this does not involve the imperfect mechanisms employed in colour recognition.
