John P. Bentley

Part I: General Principles 1. The general measurement system. 2. Static characteristics of measurement system elements. 3. The accuracy of measurement systems in the steady state. 4. Dynamic characteristics of measurement systems. 5. Loading effects and two port networks. 6. Signals and noise in measurement systems. 7. Reliability, choice and economics of measurement systems. Part II: Typical Measurement System elements. 8. Sensing elements. 9. Signal conditioning elements. 10. Signal processing elements. 11. Data presentation elements. Part III: Speciaised Measurement Systems 12. Flow measurement systems. 13. Intrinsically safe measurement systems. 14. Heat transfer effects in measurement systems. 15. Optical measurement systems. 16. Ultrasonic measurement systems. 17. Gas chromatography. 18. Data acquisition. Answers to numerical problems. Index.

OBJECTIVES: To determine the effects of risk and payment on subjects' willingness to participate, and to examine how payment influences subjects' potential behaviours and risk evaluations. METHODS: A 3 (level of risk) x 3 (level of monetary payment), between subjects, completely randomised factorial design was used. Students enrolled at one of five US pharmacy schools read a recruitment notice and informed consent form for a hypothetical study, and completed a questionnaire. Risk level was manipulated using recruitment notices and informed consent documents from hypothetical biomedical research projects. Payment levels were determined using the payment models evaluated by Dickert and Grady as a guide. Five dependent variables were assessed in the questionnaire: willingness to participate, willingness to participate with no payment, propensity to neglect to tell about restricted activities, propensity to neglect to tell about negative effects, and risk rating. RESULTS: Monetary payment had positive effects on respondents' willingness to participate in research, regardless of the level of risk. However, higher monetary payments did not appear to blind respondents to the risks of a study. Payment had some influence on respondents' potential behaviours regarding concealing information about restricted activities. However, payment did not appear to have a significant effect on respondents' propensity to neglect to tell researchers about negative effects. CONCLUSIONS: Monetary payments appear to do what they are intended to do: make subjects more willing to participate in research. Concerns about payments blinding subjects to risks could not be substantiated in the present study. However, the findings do raise other concerns--notably the potential for payments to diminish the integrity of a study's findings. Future research is critical to make sound decisions about the payment of research subjects.

This investigation has sought to determine the significance of the wide range of extractable collagen fractions which appear to exist in growing connective tissues and to determine their position in the process of fibrogenesis. Carrageenin granulomata were induced in guinea pigs and, after injection of (14)C-glycine, this tissue and skin from the same animal were subjected to successive extractions with neutral salt solutions of increasing ionic strength, citrate buffer pH 3.6, and to gelatinization. The specific activity of these fractions was determined at various time intervals. At 8 hours it was found that the specific activity decreased with increasing ionic strength of the neutral salts and was still lower in the citrate extracts and gelatin. At 36 hours the situation was almost completely reversed except that the citrate extract and gelatin still had the lowest activities. The data from skin were more clear cut than that from the granuloma and the reasons for this are discussed. It is concluded that at any given time in developing connective tissue, there is a continuous spectrum of collagen aggregates of varying degrees of strength of cross-linkage, dependent upon the time that has elapsed since their constituent molecules were synthesized. The various extraction media used remove a particular cross-section of these aggregates depending upon their disaggregating power. These extracts will thus be biologically heterogeneous. The fraction extracted with 0.14 M NaCl will contain the collagen molecules most recently synthesized and in this respect can be considered the earliest form of extracellular collagen.

An inability to lift loads great enough to disrupt muscular blood flow may impair the ability to fatigue muscles, compromising the hypertrophic response. It remains unknown what level of blood flow restriction (BFR) pressure, if any, is necessary to reach failure at very low-loads (i.e., 15%1RM). The purpose of this study was to investigate muscular adaptations following resistance training with a very low-load alone (15/0), with moderate BFR (15/40), or with high BFR (15/80), and compare them to traditional high-load (70/0) resistance training. Using a within/between subject design, healthy young participants (n=40) performed four sets of unilateral knee extension to failure (up to 90 repetitions/set), twice per week for eight weeks. Data presented as mean change (95% CI). There was a condition by time interaction for 1RM (p<.001), which increased for 70/0 [3.15 (2.04,4.25) kg] only. A condition by time interaction (p=.028) revealed greater changes in endurance for 15/80 [6 (4,8) repetitions] compared to 15/0 [4 (2,6) repetitions] and 70/0 [4 (2,5) repetitions]. There was a main effect of time for isometric MVC [change = 10.51 (3.87,17.16) Nm, p=.002] and isokinetic MVC at 180/second [change = 8.61 (5.54,11.68) Nm, p<.001], however there was no change in isokinetic MVC at 60/second [2.45 (-1.84,6.74) Nm, p=.261]. Anterior and lateral muscle thickness was assessed at 30, 40, 50, and 60% of the upper leg. There was no condition by time interaction for muscle thickness sites (all p≥.313). There was a main effect of time for all sites, with increases over time (all p<.001). With the exception of the 30% lateral site (p=.059) there was also a main effect of condition (all p<.001). Generally, 70/0 was greater. Average weekly volume increased for all conditions across the eight weeks, and was greatest for 70/0 followed by 15/0, 15/40, then 15/80. With the exception of 1RM, changes in strength and muscle size are similar regardless of load or restriction. The workload required to elicit these changes lowered with increased BFR pressure. These findings may be pertinent to rehabilitative settings, future research, and program design.

Describes the characteristics of three types of sensors currently in wide use: platinum resistance thermometers, thermistors and thermocouples. It then explains how the transfer characteristics of each sensor can be established using readily available temperature standards. The article then shows how these characteristics can be used to design signal conditioning circuits which convert the sensor output into a convenient voltage signal. Bridge circuits are necessary for the resistance thermometer and thermistor. It is possible to design a bridge with a nonlinear transfer characteristic which almost compensates for that of the thermistor. The design of an automatic reference junction circuit for a thermocouple is discussed. The article concludes by describing how a microcomputer can be incorporated into these systems as a signal processing element to improve accuracy. In the case of the thermocouple, the computer solves a quartic equation to arrive at an improved estimate of temperature.