The Deadly Rise of Anti-Science

The Deadly Rise of Anti-Science,
by Peter Hotez.

This week I read The Deadly Rise of Anti-Science: A Scientist’s Warning, by Peter Hotez. Every American should read this book. In his introductory chapter, Hotez writes

This is a dark and tragic story of how a significant segment of the population of the United States suddenly, defiantly, and without precedent turned against biomedical science and scientists. I detail how anti-science became a dominant force in the United States, resulting in the deaths of thousands of Americans in 2021 and into 2022, and why this situation presents a national emergency. I explain why anti-science aggression will not end with the COVID-19 pandemic. I believe we must counteract it now, before something irreparable happens to set the country on a course of inexorable decline…

The consequences are shocking: as I will detail, more than 200,000 Americans needlessly lost their lives because they refused a COVID-19 vaccine and succumbed to the virus. Their lives could have been saved had they accepted the overwhelming scientific evidence for the effectiveness and safety of COVID-19 immunization or the warnings from the community of biomedical scientists and public health experts about the dangers of remaining unvaccinated. Ultimately, this such public defiance of science became a leading killer of middle-aged and older Americans, more than gun violence, terrorism, nuclear proliferation, cyberattacks or other major societal threats.

Where did this 200,000 number come from? On page 2 of Intermediate Physics for Medicine and Biology, Russ Hobbie and I claim that

One valuable skill in physics is the ability to make order-of-magnitude estimates, meaning to calculate something approximately right.

Hotez gives a classic example of estimation when deriving the 200,000 number. First, he notes that 245,000 Americans died of covid between May 1 and December 31, 2021. Covid arrived in the United States in early 2020, but vaccines did not become widely available until mid 2021. Actually, the vaccines were ready in early 2021 (I had my first dose on March 20), but May 1 was the date when the vaccine was available to everyone. During the second half of 2021, about 80% of Americans who died of covid were unvaccinated. So, Hotez multiplies 245,000 by 0.8 to get 196,000 unvaccinated deaths. After rounding this off to one significant figure, this is where he gets the number 200,000.

There are a few caveats. On the one hand, our estimate may be too high. The vaccine is not perfect. If all of the 200,000 unvaccinated people who died would have gotten the vaccine, some of them would still have perished from covid. If we take the vaccine as being 90% effective against death, we would multiple 196,000 times 0.9 to get 176,400. On the other hand, our estimate may be too low. Covid did not end on January 1, 2022. In fact, the omicron variant swept the country that winter and at its peak over 2000 people died of covid each day. So, the total covid deaths since the vaccine became available—the starting point of our calculation—is certainly higher than 245,000.

As Hotez points out, other researchers have also estimated the number of unnecessary covid deaths, using slightly different assumptions, and all the results are roughly consistent, around 200,000. (Hotez’s book appears to have been written in mid-to-late 2022; I suspect the long tail of covid deaths since then would not make much difference to this estimation, but I’m not sure.) 

In the spirit of an order-of-magnitude estimate, one should not place too great an emphasis on the precise number. It was certainly more than twenty thousand and it was without a doubt less than two million. I doubt we’ll ever know if the “true” amount is 187,000 or 224,000 or any other specific value. But we can say with confidence that about a couple hundred thousand Americans died unnecessarily because people were not vaccinated. Hotez concludes

That 200,000 unvaccinated Americans gave up their lives needlessly through shunning COVID-19 vaccines can and should haunt our nation for a long time to come.

Infectious disease scientists such as Peter Hotez, Tony Fauci, and others are true American heroes. That far-right politicians and journalists vilify these researchers is despicable and disgusting. We all owe these scientists so much. Last Monday was “Public Health Thank You Day” and yesterday was Thanksgiving. I can think of no one more deserving of our thanks than the scientists who led the effort to vaccinate America against covid. 

Why Science Isn’t Up for Debate, with Peter Hotez.

https://www.youtube.com/watch?v=PbGfeksduGE

Gustav Bucky and the Antiscatter Grid

An antiscatter grid.
Episcophagus, CC BY-SA 4.0,
via Wikimedia Commons.

In Chapter 16 of Intermediate Physics for Medicine and Biology, Russ Hobbie and I discuss the antiscatter grid used in radiography.

Since the radiograph assumes that photons either travel in a straight line from the point source in the x-ray tube to the detector or are absorbed, Compton-scattered photons that strike the detector reduce the contrast and contribute an overall background darkening. This effect can be reduced by placing an antiscatter grid (or radiographic grid, or “bucky” after its inventor, Gustav Bucky) just in front of the detector.

Who is Gustav Bucky? We can learn more about his life and work by examining the chapter “Two Centenaries: William Coolidge & Gustav Bucky,” by Elizabeth Beckmann and Adrian Thomas, in The Story of Radiology (Volume 2), published by the European Society of Radiology. Beckmann and Thomas begin

Gustav Peter Bucky was born on September 3, 1880 in Leipzig, Germany. He wanted to be an engineer, however at the insistence of his parents he transferred to study medicine at the University of Leipzig, graduating in1906. The combination of his interest in photography at school, his ambition to be an engineer and his parent’s insistence that he study medicine would lead him into the relatively new technical branch of medicine which was to be called radiology.

I’ve seen many reasons for scientists to straddle between physics/engineering and biology/medicine. In Bucky’s case the reason was parental pressure.

Beckmann and Thomas of course mention Bucky’s biggest contribution to science, his antiscatter grid.

It was Gustav Bucky who realised that the main problem was finding a way to reduce the scattered radiation that was responsible for the loss of definition of the radiological image from reaching the film. However, this had to be achieved with minimum impact on the primary x-ray beam. Bucky had his original idea on how to achieve this in 1909, but it took some years of experimenting for him to develop his design.

Bucky described his original design for the ‘Bucky Diaphragm’ as a ‘honeycomb’ lead grid, but with individual elements being square in shape, rather than hexagonal. He used lead since it was a material which absorbed x-rays. In this design the lead strips were thick and spaced 2 cm apart, running both parallel to the length and width of the film. This resulted in the lines of the grid being visible on the x-ray film. Despite this, the grid was effective and did remove scatter and improve image contrast.

You can eliminate those artifact lines by moving the grid.

In 1920, the American Hollis Potter further developed the grid. Potter aligned the lead strips so that they now ran in one direction only, and he also made the lead strips thinner so that they were less visible on the image. Potter also proposed moving the grid during exposure, which blurred out the image of the lead strips on the radiographic image... The resulting moving grid, based upon the work of Bucky and Potter, became known as the Potter-Bucky grid.

Albert Einstein and Gustav Bucky,
Leo Baeck Institute, F 5347B.

Bucky moved from Germany to the United States in 1929. He became good friends with Albert Einstein.

In 1933, Bucky met up again with his friend Albert Einstein when he arrived in New York. When on holiday together Gustav and Albert would go for a long walk together each day, discussing and developing new ideas…

Probably the most famous collaboration between Bucky and Einstein was the idea of ‘a light intensity self-adjusting camera’ with a US patent granted on October 27, 1936...

It is a sign of the close relationship between Bucky and Einstein that Bucky visited Einstein every day during his final illness and was at the hospital only hours before Einstein’s death in April 1955.

The story concludes

Gustav Bucky was a friendly, modest, undemanding person who made a lasting and significant contribution to radiology. For 21st century radiology the impact of the invention for which Gustav Bucky is most remembered – the Bucky Grid – continues. The grid is as important in modern digital detection systems, like computed radiography (CR) plates or digital radiography (DR) detector systems, as it was with x-ray film in the 1920s. 

Monet's Water Lilies

When my wife and I were in Paris several years ago we visited the Musée de l’Orangerie, where Claude Monet’s beautiful water lily murals are displayed. Monet (1840–1926) is the famous impressionist painter who, during the last decades of his life, painted lilies floating on the surface of the pond at his home in Giverny. I remember sitting in one of the oval rooms staring at these giant paintings. It was so quiet and peaceful.

Monet’s water lily murals in the Musée de l’Orangerie in Paris.
Brady Brenot, CC BY-SA 4.0 , via Wikimedia Commons.

Water lilies take advantage of some interesting physics. First, their stalks and leaves contain air pockets, reducing their average density and making them buoyant. Russ Hobbie and I compare the effect of buoyancy in terrestrial and aquatic animals. I quote this comparison below, but I have replaced the word “animals” by “plants”.

Plants are made up primarily of water, so their density is approximately 10³ kg m⁻³. The buoyant force depends on the plant’s environment. Terrestrial plants live in air, which has a density of 1.2 kg m⁻³. The buoyant force on terrestrial plants is very small compared to their weight. Aquatic plants live in water, and their density is almost the same as the surrounding fluid. The buoyant force almost cancels the weight, so the plant is essentially “weightless.” Gravity plays a major role in the life of terrestrial plants, but only a minor role for aquatic plants. Denny (1993) explores the differences between terrestrial and aquatic plants in more detail.

Another piece of physics important to water lilies is surface tension, a topic only briefly mentioned in the fifth edition of Intermediate Physics for Medicine and Biology, but which (spoiler alert!) may play a larger role in the sixth edition. The lily’s leaf is waxy, which repels water and enhances its ability to remain on the water-air surface. In addition, small cilia increase the surface area.

A last bit of physics has to do with the surface-to-volume ratio. Usually surface tension can’t support a large object, because its weight increases with the cube of its linear size, whereas the effect of surface tension increases with the object’s perimeter. Therefore, the impact of gravity increases with size more dramatically than does the impact of surface tension, so a large object sinks like a rock. The water lily’s leaf, however, is thin, and making the leaf larger increases its surface area but not its thickness. The weight only increases as the square of its linear size, not as the cube. If the leaf is large enough, gravity will still win out, but the leaf can be larger than you might expect and still float on the water surface.

Monet donated his water lily murals to France at the end of World War I, to create a place where people could reflect on those who gave their life for the nation. When visiting them, you can also contemplate the role of physics in medicine and biology.

Happy Veterans Day.

One of Monet’s water lily murals at the Musée de l’Orangerie.

Monet’s Water Lilies: Great Art Explained.

 https://www.youtube.com/watch?v=fd-Me3EBGYY&t=7s

The Golay Coil

Last week I introduced the Helmholtz coil and the Maxwell coil. The Maxwell coil is useful for creating the magnetic field gradient needed for magnetic resonance imaging. At the end of the post, I wrote

The Maxwell coil is great for producing the magnetic field gradient dB_z/dz needed for slice selection in MRI, but what coil is required to produce the gradients dB_z/dx and dB_z/dy needed during MRI readout and phase encoding? That, my friends, is a story for another post.

Today, I will finish the story.

First, let’s assume the gradient coils are all located on the surface of a cylinder. If this were a clinical MRI scanner, the person would lie on a bed that would be slid into the cylinder to get an image. The Maxwell coil consists of two circular coils, separated by a distance equal to the square root of three times the coil radius. The parts of the coil in the back that are hidden by the cylinder are shown as dashed. The two coils carry current in opposite directions, as shown below, creating a gradient dB_z/dz in the imaging region midway between the two coils on the axis of the cylinder.

To perform imaging, however, you need gradients in the x and y directions too. To create dB_z/dx, you typically use what is called a Golay coil. It consists of four coils wound on the cylinder surface as shown below. 

The mathematics to determine the details of this design is too complicated for this post. Suffice to so, it requires setting the third derivative of B_z with respect to x equal to zero. The resulting coils should each subtend an angle of 120°. Their inner loops should be separated by 0.778 cylinder radii, and their outer loops by 5.14 radii.

To create the gradient dB_z/dy, simply rotate the Golay coil by 90°, as shown below. 

So, to perform magnetic resonance imaging you need a nested set of three coils as shown below. 

The picture gets confusing with all the hidden lines. Here is how the set looks with the hidden parts of the coils truly hidden.

While this set of coils will produce linear magnetic field gradients in the central region, in state-of-the-art MRI scanners the coils are somewhat more complicated, with multiple loops corresponding to each loop shown above.

We all know who Helmholtz and Maxwell are, but who is Golay? Marcel J. E. Golay (1902-1989) was a Swiss scientist who came to the US to get his PhD at the University of Chicago and then stayed. He had a varied career, making fundamental advances in chromatography, information theory, and the detection of infrared light. He studied the process of shimming: making small adjustments to the magnetic field of a MRI scanner to make the static field more homogeneous. This work ultimately led to the design of gradient coils.

In Chapter 18 of Intermediate Physics for Medicine and Biology, Russ Hobbie and I discuss magnetic resonance imaging and the need for magnetic field gradients. In a nutshell, MRI converts magnetic field strength to spin precession frequency. By measuring this frequency, you can obtain information about magnetic field strength. A magnetic field gradient lets you map frequency to position, an idea which is at the heart of imaging using magnetic resonance.