In the November 13, 2020 episode of ( Season 12, Episode 5), two earnest entrepreneurs, Ken and Allyson, try to persuade five investors, the “sharks,” to buy into their company. The entrepreneurs sell LIFTiD, a device that applies a small steady current to the forehead. Ken said it’s supposed to improve “productivity, focus, and performance.” Allyson claimed it’s a “smarter way to get a… boost of energy.”

The device is based on transcranial direct current stimulation (tDCS). In 2009 I published an editorial in the journal Clinical Neurophysiology to accompany a paper appearing in the same issue by Pedro Miranda


Voodoo Science,
by Robert Park

These days — when so many people believe crazy conspiracy theories, refuse life-saving vaccines, promote alternative medicine, fret about perceived 5G cell phone hazards, and postulate implausible microwave weapons to explain the Havana Syndrome — we need to understand better how science interacts with society. In particular, we should examine similar controversies in the past to see what we can learn. In this post, I review the power line/cancer debate of the 1980s and 90s. I remember it well, because it raged during my graduate school days. …


In last week’s post, I discussed the Bragg peak: protons passing through tissue lose most of their energy near the end of their path. In Chapter 16 of Intermediate Physics for Medicine and Biology, Russ Hobbie and I present a homework problem in which the student calculates the stopping power (energy lost per distance traveled), S, as a function of depth, x, given a relationship between stopping power and energy, T. This problem is a toy model illustrating the physical origin of the Bragg peak. Often its helpful to have two such exercises; one to assign as homework and one…


Energy loss versus depth for a 150 MeV proton beam in water, with and without straggling (fluctuations in the range). The Bragg peak enhances the energy deposition at the end of the proton range. Adapted from Fig. 16.47 in Intermediate Physics for Medicine and Biology.

In Chapter 16 of Intermediate Physics for Medicine and Biology, Russ Hobbie and I discuss the Bragg peak.

Protons are also used to treat tumors (Khan 2010, Ch. 26; Goitein 2008). Their advantage is the increase of stopping power at low energies. It is possible to make them come to rest in the tissue to be destroyed, with an enhanced dose relative to intervening tissue and almost no dose distally (“downstream”) as shown by the Bragg peak in Fig.16.47.


Alan Magee. Reproduced from the website www.americanairmuseum.com.

On January 3, 1943, airman Alan Magee fell 22,000 feet (6700 meters, or about 4 miles) without a parachute from a damaged B-17 Flying Fortress and survived. How’d he do it?

Let’s examine Magee’s fall using elementary physics. Homework Problem 29 in Chapter 2 of Intermediate Physics for Medicine and Biology explains how someone falling through the air reaches a steady-state, or terminal, speed. A typical terminal speed, v, when skydiving is about 50 m/s. This may be a little slower than average, but v decreases with mass and ball turret gunners like Magee were usually small. Skydivers will reach…


When a particle travels faster than the speed of light, it emits Cerenkov radiation. This phenomenon has resulted in new medical imaging applications, as described in a 2017 review paper by Esther Ciarrocchi and Nicola Belcari ( Cerenkov Luminescence Imaging: Physics Principles and Potential Applications in Biomedical Sciences, EJNMMI Physics, Volume 4, Article 14). This is an open access article, so you can read it for free.

Russ Hobbie and I don’t discuss Cerenkov Luminescence Imaging in Intermediate Physics for Medicine and Biology, but you can learn a lot about it using the physics we do discuss. For example, can…


Why is my field — bioelectromagnetics — so prone to pseudoscience? I don’t know. But I do know that we need to be more skeptical about alternative medical treatments. That’s why I’m a fan of the website sciencebasedmedicine.org.

Science-Based Medicine is dedicated to evaluating medical treatments and products of interest to the public in a scientific light, and promoting the highest standards and traditions of science in health care. Online information about alternative medicine is overwhelmingly credulous and uncritical, and even mainstream media and some medical schools have bought into the hype and failed to ask the hard questions.

We…


An Inspire TV ad.

I suspect you’ve seen some of the recent ads for Inspire, a new treatment for obstructive sleep apnea.

How does Inspire work? It uses electrical stimulation, like Russ Hobbie and I discuss in Chapter 7 of Intermediate Physics for Medicine and Biology.

7.10 Electrical Stimulation

The information that has been developed in this chapter can also be used to understand some of the features of stimulating electrodes. These may be used for electromyographic studies; for stimulating muscles to contract called functional electrical stimulation (Peckham and Knutson 2005); for a cochlear implant to partially restore hearing (Zeng…


“The Bidomain Model of Cardiac Tissue:
Predictions and Experimental Verification”

In the early 1990s, I was asked to write a chapter for a book titled Neural Engineering. My chapter had nothing to do with nerves, but instead was about cardiac tissue analyzed with the bidomain model. (You can learn more about the bidomain model in Chapter 7 of Intermediate Physics for Medicine and Biology.)

“The Bidomain Model of Cardiac Tissue: Predictions and Experimental Verification” was submitted to the editors in January, 1993. Alas, the book was never published. However, I still have a copy of the chapter, and you can download it here. …

Brad Roth

Professor of Physics at Oakland University and coauthor of the textbook Intermediate Physics for Medicine and Biology.

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