Showing posts with label polio vaccine. Show all posts
Showing posts with label polio vaccine. Show all posts

Another anti-vax paper bites the dust

Anti-vaxxers learned a lesson from discredited, de-licensed former doctor Andrew Wakefield, who in 1998 published a badly flawed article in The Lancet pushing a link between vaccines and autism. Wakefield's study was eventually shown to be not only flawed but fraudulent, leading all of the co-authors except Wakefield himself to disavow it, and in 2010 the journal finally retracted it after Wakefield lost his medical license.

But it took The Lancet 12 years to retract the paper, and in that time the anti-vaccine movement flourished. Wakefield became a hero within that movement, and continues to push his anti-vaccine propaganda today, even making films presenting himself as a lone hero fighting for truth.

Other anti-vaxxers are very familiar with this saga, and they have followed Wakefield's recipe by writing scientific papers and attempting to get them published in reputable journals. Usually they fail, but now and then one slips through, which they then point to as "proof" that vaccines are harmful.

The latest example is a paper that appeared in Scientific Reports in November 2016 and that the journal just retracted last week. It has a title that sounds highly technical: "Murine hypothalamic destruction with vascular cell apoptosis subsequent to combined administration of human papilloma virus vaccine and pertussis toxin." (Wakefield's 1998 paper had a similarly obscure title.)

What that lengthy title hides is the paper's anti-vaccine message: that the HPV vaccine might cause neurological damage. The paper was quickly called out as pseudoscience by the scientific community, who reacted within days in the blogosphere and elsewhere, as described by a news article in Science that appeared just after the paper's publication.

(Aside: the HPV vaccine protects people from human papillomavirus, which causes many cases of cervical cancer as well as throat cancer. It's the first vaccine that prevents these cancers, which is an amazing breakthrough. Millions of doses have been administered with essentially zero cases of harm.)

What did the paper do? Basically, it was a setup. The authors–most of them from Tokyo Medical University–gave mice a huge dose of HPV vaccine plus (here's the kicker) a large dose of pertussis toxin. There's no valid reason to administer that toxin except to try to induce brain damage, which the authors could then blame on the HPV vaccine. The study design was clearly awful, and the paper should never have been published.

Just after the paper appeared, two groups of scientists wrote to the Nature publishing group (which publishes Scientific Reports) to protest, as reported in the Science story. One letter, from a group of HPV experts at the University of Antwerp, explained that:
"This experimental setup in no way mimics the immunization with HPV vaccines but is gross over-dosage and manipulation of membrane permeability."
This is putting it mildly. For a blunter assessment, see Orac's aptly titled "Torturing more mice in the name of antivaccine pseudoscience," which appeared in November 2016.

What was not publicly known before now was that I too wrote to the journal editors, asking them to "take action quickly, rather than waiting for over 10 years as The Lancet did." First I wrote to the immunology sub-editor, who forwarded my letter to the Editor-in-Chief, Richard White. Dr. White replied on 29 Nov 2016 that "We are looking into the specific issues raised regarding this paper."

That was the last I heard of it, until the journal announced last week that they have retracted the paper.

So in the end, the scientific record was corrected. But why did it take Scientific Reports 18 months to do it? Haven't they learned from the Wakefield debacle how much damage can be done while antivaccine articles like this one remain in the literature? The journal's editors had a responsibility to act more quickly, and they failed. The scientists who wrote those letters back in 2016 had the same complaint, as reported by Dennis Normile in Science last week. Not surprisingly, Scientific Reports refused to comment (when asked by Science) on any details of their review process.

That's not good enough. Scientific Reports is a "mega-journal," a new type of journal that publishes thousands of papers per year, with a relatively low bar for acceptance. The idea (not a bad one, in theory) is that any valid scientific study, even one that makes only a very small contribution, still merits publication somewhere.

What publishers have learned is that these mega-journals are very profitable, because they charge a publishing fee that more than covers their costs. In return for these profits, Nature Publishing has an obligation to remove harmful papers far faster than they did in this case. Otherwise, it's only a matter of time before anti-vaxxers do this again.

Finally, let me repeat something that can't be said often enough: vaccines are perhaps the single greatest medical advance in human history. They have saved millions of lives, and they continue to save lives today. Scourges such as smallpox and polio, which once swept through populations causing terrible pain, suffering, and death, have been conquered thanks to vaccines. Medical researchers continue to work on new vaccines against the infections that still plague us, and they are the real heroes.



The Physics of Golf

[Herman Erlichson was a physicist and a historian of science (he had Ph.D.s in both). He was also an avid golfer, and he was my uncle.  He passed away just over a year ago, and I've been wanting to write this column ever since.  We corresponded frequently when I was a teenager, in a time when hand-written letters were still common.  Here is a small anecdote.]

Everyone who plays golf knows that the driver hits the ball the farthest of any club.  It also has the lowest launch angle, or "loft."  Clubs with high loft, such as a sand wedge, pop the ball very high up in the air, but don't hit it very far.

The universe of people who both play golf and also know college-level physics may not be very large, but everyone in this club has puzzled over this conundrum: why is it that a driver has a loft of only about 10 to 12 degrees?  That seems far too low.

Exactly 30 years ago this month, my uncle Herman Erlichson figured this out.  It's the spin.

He published the answer in a serious physics journal [1], but I'm guessing that most golfers don't read physics journals.  So here is what he found.

Everyone in freshman physics learns that the optimal launch angle for a projectile - the angle that makes a ball fly the farthest - is 45 degrees, in a vacuum.  But in the game of golf, 45 degrees is the angle of a pitching wedge, which (as every golfer knows) hits the ball only a short distance, about half as far as a driver.

Now the physics calculation assumes that the ball is in a vacuum, but still: how come the presence of air makes the optimum angle so much lower?  Or as my uncle put it, in his classic understated style:
"The large discrepancy between the approximately 11 deg of loft for the golf driver club and the 45 deg maximum range angle for a vacuum was the motivation to begin a study of the question of maximum projectile range in the presence of air resistance, with particular application to the flight of a golf ball." [1]
The analysis itself is technically very complex, involving 3 forces: gravity, drag (resistance caused by air friction), and lift, caused by the backspin on the ball.  All three are big factors, but the theoretical result of 45 degrees only accounts for gravity.  

Air friction (or drag) turns out to have a quadratic effect, as my uncle showed.  In other words, the drag increases in proportion to the square of the velocity of the ball.  So hitting it harder causes a very rapid increase in drag.  Here's his graph showing how the angle is affected by quadratic drag:
One consequence of "quadratic drag" is that hitting the ball a lot harder only yields a modest increase in distance.  More important, though, is that if we just consider gravity plus drag, the best angle to launch a golf ball is 35 degrees.  Lower than 45, but still nowhere near the angle of a modern driver.  And the distance here is still too low, only 336 feet (112 yards).

My uncle Hymie figured out that backspin makes a huge difference. Backspin generates lift, keeping the ball in the air much, much longer.  My uncle derived equations that allowed him to calculate how the lift force increases with the rate of spin and the speed of the ball.  This produced a very different picture of how far the ball would carry at different angles, shown here:
After accounting for lift, the optimum angle is 16 degrees, and the ball flies about 200 yards.  (This assumes a typical launch speed by the standards of 1983. The much longer drivers used today create a much greater speed off the tee.)  The remaining different between the actual loft of 10-12 degrees can be explained by the fact that for a drive, the teed-up ball is struck just past the bottom of the swing. This makes the launch angle slightly higher than the loft of the club.

There you have it: when you account for all the forces at play, the optimum angle for a golf driver really is around 10-12 degrees.

My uncle Herman Erlichson loved the game of golf and played often, despite having a seriously weakened leg, the after-effect of a polio infection that he contracted in the 1950's.  He might have struggled to master the game itself, but when it came to the physics of golf, he solved a mystery that had puzzled physicist-golfers for decades.

Reference
H Erlichson. American Journal of Physics 51:4 (1983), pp. 357-362.

For all 95 of Herman Erlichson's scholarly papers, including his paper on the physics of golf, see his Google Scholar page.