A transmission line equivalent circuit for piezoelectric transducers has been modified to provide modeling of lossy piezoceramic transducers. A lossy transmission line is used to model the mechanical losses. The equivalent circuit parameters are derived from analogies between electrical transmission lines and acoustic wave propagation. Implementation of the equivalent circuit model in SPICE is shown. Simulations and measurements in the time and frequency domain of a low-Q material and a multilayered ultrasonic sensor using a low-Q piezoceramic transducer are presented.

Germans spend an average of more than 3 hours watching television each day. Among them, there are many who turn on their TV sets for less than 1.5 hours a day, and others who do this for more than 8 hours a day. What accounts for these differences? The central thesis in this paper is that individuals may be distinguished by their attitude toward thinking and that differences in their need for cognition explain the differences in their time spent with TV. The lower viewers' need for cognition is, the less pleasant they feel when they have nothing to do because there is nothing left to do but think. The easiest way for individuals to escape this pressure to think is by watching TV. Thus, individuals will watch more TV when they have a lower need for cognition. Results of a survey study show that the concept of escapism proves to be useful in explaining TV use when it takes over a psychological perspective as well as a sociological one.In 1998, Germans over the age of 13 spent an average of 3 hours and 20 minutes watching television each day (Darschin, 1999, p. 154). This average represents a distribution of individual values with considerable variation: For example, there are approximately 27 million nonviewers and light viewers in Germany who watch television less than 1.5 hours each day, and there are also approximately 15 million heavy viewers who watch television more than 6 hours each day, including 3 million Germans who watch TV more than 8 hours daily (Fischer, 1997, p. 41). The causes of such individual differences in amount of television viewing remain largely unexplained, although researchers have attempted to attribute them to sociodemographic variables. As Schulz (1987) has noted: [S]ociodemographic variables can only explain 13 percent of the variance within the viewing amount. The large unexplained percentage of variance is a challenge for the media-science. The important question, which social and psychological characteristics distinguish light viewers from heavy viewers, has up to now been answered only to a small degree.

A chamber for indirect calorimetry has been constructed that utilises previously published general equations for the calculation of respiration. Owing to the large size of the chamber, the changes in gas concentration caused by a subject are very small. Therefore, algorithms are developed for noise suppression and trend identification. Using the exact solution of the equations for steady state, each gas concentration is fitted by a least square method to two connected exponential segments, of variable length, for the preceding 30 min period. Independently of the location of the join between the two segments, the gas concentration and its time derivative are evaluated at -15 min. This process is repeated, and its results are presented once every minute. As proven by gas injection tests, this procedure gives an instantaneous response to a single change in respiration, a correct averaging of repeated changes in respiration with periods of less than 15 min and noise suppression. It is concluded that this chamber is useful not only for traditional 24 h energy expenditure measurements, but also for experiments requiring rapid responses.

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