Accelerator mass spectrometry (AMS) is an ultrasensitive analytical technique for measuring rare nuclides such as 14 C, 26 Al and 41 Ca. The low detection limit and wide dynamic range of AMS allow long-term and highly sensitive tracer studies in nutrition that cannot be performed with other methods. The present paper is intended to provide a description of AMS to the interested nutritionist and present proven applications. AMS is compared to liquid scintillation counting and stable isotope MS. A description of common AMS methodology is presented that consists of determining the dose, preparing the sample, diluting the sample (if necessary), and measuring the sample. Applications include Ca metabolism, Al uptake from the environment, dietary intake of carcinogens, fat metabolism and folate metabolism. Throughout this discussion the experimental advantages (small doses that pose no health risk, extremely long experimental lifetime, small sample sizes and high sensitivity) made possible by the unique analytical capabilities of AMS are emphasized. The future of AMS is discussed. As the number of AMS centres, instruments, and studies increases, the number of nutritional applications that employ AMS will continue to grow. The coupling of AMS with other analytical techniques (e.g. high performance liquid chromatography) will be developed as access to AMS improves.Accelerator mass spectrometry: Stable isotopes: Micronutrient metabolism: Fat metabolism: Carcinogens: Radioisotope

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We present a switched linear system approach for modeling the complex nonlinear dynamics associated with temperature inversion occurring in thermally stratified hot water tanks. Such tanks are commonly used for thermal energy storage, particularly in low- to medium-temperature waste heat recovery applications. By separating the influence of temperature inversion from the internal heat transfer between states in the governing differential equations, we paramaterize the nonlinearity using a vector of discrete variables. This vector is then used to define the switching between a set of linear, discrete time models. The proposed switched model is validated against a reduced-order nonlinear model of the thermal energy storage and then integrated with a fuel cell model to capture the dynamics of a micro-combined heat and power system. Simulation results demonstrate the importance that temperature inversion has on the stratification dynamics which in turn has implications for control of such systems.