Applications of modern physics in medicine

Many remarkable medical technologies, diagnostic tools, and treatment methods have emerged as a result of modern physics discoveries in the last century--including X-rays, radiation treatment, laser surgery, high-resolution ultrasound scans, computerized tomography (CT) scans, and magnetic resonance imaging. This undergraduate-level textbook describes the fundamental physical principles underlying these technological advances, emphasizing their applications to the practice of modern medicine. Intended for science and engineering students with one year of introductory physics background, this textbook presents the medical applications of fundamental principles of physics to students who are considering careers in medical physics, biophysics, medicine, or nuclear engineering. It also serves as an excellent reference for advanced students, as well as medical and health researchers, practitioners, and technicians who are interested in developing the background required to understand the changing landscape of medical science. Practice exercises are included and solutions are available separately in an instructor's manual. Complete discussion of the fundamental physical principles underlying modern medicineAccessible exploration of the physics encountered in a typical visit to a doctorPractice exercises are included and solutions are provided in a separate instructor's manual (available to professors)A companion website (modernphysicsinmedicine.com) presents supplementary material

Trace gas emission in chambers: a non-steady-state diffusion model, Soil Sci

ABSTRACT Non-steady-state (NSS) chambers are widely used to measure trace gas emissions from the Earth's surface to the atmosphere. Unfortunately, traditional interpretations of time-dependent chamber concentrations often systematically underestimate predeployment exchange rates because they do not accurately represent the fundamental physics of diffusive soil gas transport that follows chamber deployment. To address this issue, we formally derived a time-dependent diffusion model applicable to NSS chamber observations and evaluated its performance using simulated chamber headspace CO 2 concentration data generated by an independent, three-dimensional, numerical diffusion model. Using nonlinear regression to estimate the model parameters, we compared the performance of the non-steady-state diffusive flux estimator (NDFE) to that of the linear, quadratic, and steady-state diffusion models that are widely cited in the literature, determined its sensitivity to violation of the primary assumptions on which it is based, and addressed some of the practicalities of its application. In sharp contrast to the other models, NDFE proved an accurate and robust estimator of trace gas emissions across a wide range of soil, chamber design, and deployment scenarios