An apparatus for quantitative measurement of ventilation in unrestrained small animals is described. The subject rests in an environmental chamber, and respiration is indicated by barometric pressure oscillations proportional to tidal volume. The chamber is purged continuously at a relatively high flow rate during studies. Thus, CO2 does not accumulate and long-term measurement can proceed without interruption. Respiratory control studies are especially facilitated since different gas mixtures can be rapidly passed through the chamber. An electronic device also is described which automatically calculates expired minute volumes (VE) from the pressure signal obtained from the plethysmograph.

The accuracy of the formula derived by Drorbaugh and Fenn (Pediatrics 16: 81-86, 1955) for calculating tidal volume (VT) from the phasic pressure change measured when an animal breathes in a closed chamber has recently been challenged. Epstein and Epstein (Respir. Physiol. 32: 105-120, 1978) argue that the formula may underestimate VT by up to 30% and predict that the error increases as the ratio of inspiratory duration (TI) to total breath duration (Ttot) increases, and as the expired temperature at the nares (TN) increases. To test their theory, I measured VT in anesthetized rats by the barometric technique and by conventional pneumotachography simultaneously. TN was varied from ambient to body temperature by passing a variable current through the pneumotachograph heater; TI/Ttot was varied by changing FICO2 and by selecting different rats. The predictions were confirmed. A factor is derived for retrospectively correcting VT estimated by the Drorbaugh-Fenn formula. It requires knowledge of TN and TI/Ttot and reduces the error between experiments to under 20% and within each experiment to about 5%. To facilitate its use, TN was measured in rat, rabbit, cat, man, and infant pigtail monkey.

This book teaches model-based analysis and model-based testing, with important new ways to write and analyze software specifications and designs, generate test cases, and check the results of test runs. These methods increase the automation in each of these steps, making them more timely, more thorough, and more effective. Using a familiar programming language, testers and analysts will learn to write models that describe how a program is supposed to behave. The authors work through several realistic case studies in depth and detail, using a toolkit built on the C# language and the .NET framework. Readers can also apply the methods in analyzing and testing systems in many other languages and frameworks. Intended for professional software developers including testers, and for university students, this book is suitable for courses on software engineering, testing, specification, or applications of formal methods.

We show how model-based on-the-fly testing can be applied in the context of web applications using the NModel toolkit. The concrete case study is a commercial web-based positioning system called WorkForce Management (WFM) which interacts with a number of other services, such as billing and positioning, through a mobile operator. We describe the application and the testing, and discuss the test results.