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Global Good (Testing Passive Cooler on Camel)

Understanding Vaccination: The Cold Chain

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Global Good (Testing Passive Cooler on Camel)

Delivering vaccines is hard work. One of the hardest—and least-discussed—problems of vaccination is the cold chain, the challenge of keeping a vaccine at cold temperatures all the way from production, through shipping to a given country, through local delivery to a health clinic, and finally delivery into someone's body. As we continue World Immunization Week, let's dig in to this slightly geeky technical problem—one that literally means the difference between life and death.

Why Keep Vaccines Cold?

While some vaccines are stable at a relatively wide range of temperatures (some as hot as 40° C), most vaccines must be kept cold in order to maintain their potency. What's more, some vaccines must be kept in a strictly controlled range of temperatures (typically 2°-8° C) or they go bad. Temperatures too cold or too warm can cause a dose of vaccine to lose its "immunogenicity," or its ability to affect the human immune system.

There's a related problem here: Some vaccines that are able to be exposed to higher temperatures are not labeled as such. This causes workers to refrigerate those vaccines unnecessarily (treating all of them the same), which is a waste of energy.

Why Is This A Challenge?

Almost 50% of health posts providing vaccines have no (or very minimal) access to the power grid. Without grid power, it's hard to have reliable refrigeration (and even if you have grid power, in some parts of the world that means lots of outages—which can be hard on a refrigeration unit).

Transporting cold vaccines to remote areas and then storing them properly in those locations are both serious problems due to the general lack of reliable electricity for cooling. In some parts of the world, we're talking about literally packing a foam cooler with ice and vaccine, then carrying that cooler to a village.

To compound the cold chain's core logistical challenge, we are now able to vaccinate children against more diseases than ever. This is great! But more kinds of vaccines means more vaccine volume to carry around and keep cold. One estimate shows that the volume of vaccine per child has gone from 50cm3 in 1980 to 200cm3 in 2010. That's a fourfold increase in vaccine volume per child, to protect against roughly 2.5 times the number of diseases over the same time period.

Promising Solutions

The best solution to this problem would be the development of vaccines that do not require refrigeration. While work is underway, it may not be possible for certain kinds of vaccines, and even if it becomes possible, that doesn't solve any problems today; the R&D is years out. But, for the record, "thermostable" vaccines are what we hope for down the road—along with better labeling of the ones we have today.

There are also interesting technological solutions in testing. The simplest is a "passive long-term cooler," which you may know better as "a really big, beefy Thermos©-style container." When you make the leap from traditional "tailgate party cooler full of ice" to a precisely engineered vacuum flask, you can extend the cold storage from a matter of hours to an entire month with no power. This is huge, it's cheap, and it's simple. (On the hand, it does require ice...which typically requires refrigeration to create.)

Another approach for health posts without grid power is a Solar Direct Drive. These devices use solar power to drive a compressor, creating ice, then store power in the ice rather than in a battery. This is more resilient to power losses than a traditional refrigerator or battery pack, and a large block of ice can keep the system cool for up to five days even if solar input is low or nonexistent (for instance, on cloudy days).

The final technological solution in the pipeline is Ice-Lined Refrigerators (ILRs). These exist today, but improvements to the basic technology could mean these refrigerators could operate on about 8 hours of grid power per day, and still keep vaccines in the required cool range for several days in the event of a power failure.

Systems Thinking

The cold chain is a logistical problem with many inputs. To improve its performance, we have to think about all sides of the problem: improved vaccines (ideally requiring less refrigeration or less volume); improved refrigeration (requiring less or no power); and improved delivery systems (only deliver the needed amount of a vaccine to a given area "just in time," reducing the need for local storage off the grid). All of these elements are in play.

In a recent pilot program in Nigeria's Lagos State, all these elements were addressed. At the beginning of the trial, half the district health posts had inadequate vaccine stock on hand; at the end, all were properly stocked. After the program, pentavalent vaccination rates had risen by 15% within just one month. (The "penta" vaccine protects against five diseases: diphtheria-tetanus-pertussis (DTP), hepatitis B, and Haemophilius influenzae type B.) Nigeria is just one of three countries (the others being Afghanistian and Pakistan) in which polio is still endemic, so improvements to vaccination there are key to beating polio.

The take-away: by tackling the cold chain problem from multiple angles, we can improve delivery of vaccines, reduce waste, and save both lives and money. That's a goal worth fighting for.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Library of Congress
10 Facts About the Tomb of the Unknown Soldier
May 29, 2017
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Library of Congress

On Veterans Day, 1921, President Warren G. Harding presided over an interment ceremony at Arlington National Cemetery for an unknown soldier who died during World War I. Since then, three more soldiers have been added to the Tomb of the Unknowns (also known as the Tomb of the Unknown Soldier) memorial—and one has been disinterred. Below, a few things you might not know about the historic site and the rituals that surround it.


Wikimedia Commons // Public Domain

To ensure a truly random selection, four unknown soldiers were exhumed from four different WWI American cemeteries in France. U.S. Army Sgt. Edward F. Younger, who was wounded in combat and received the Distinguished Service Medal, was chosen to select a soldier for burial at the Tomb of the Unknowns in Arlington. After the four identical caskets were lined up for his inspection, Younger chose the third casket from the left by placing a spray of white roses on it. The chosen soldier was transported to the U.S. on the USS Olympia, while the other three were reburied at Meuse Argonne American Cemetery in France.


One had served in the European Theater and the other served in the Pacific Theater. The Navy’s only active-duty Medal of Honor recipient, Hospitalman 1st Class William R. Charette, chose one of the identical caskets to go on to Arlington. The other was given a burial at sea.


WikimediaCommons // Public Domain

The soldiers were disinterred from the National Cemetery of the Pacific in Hawaii. This time, Army Master Sgt. Ned Lyle was the one to choose the casket. Along with the unknown soldier from WWII, the unknown Korean War soldier lay in the Capitol Rotunda from May 28 to May 30, 1958.


Medal of Honor recipient U.S. Marine Corps Sgt. Maj. Allan Jay Kellogg, Jr., selected the Vietnam War representative during a ceremony at Pearl Harbor.


Wikipedia // Public Domain

Thanks to advances in mitochondrial DNA testing, scientists were eventually able to identify the remains of the Vietnam War soldier. On May 14, 1998, the remains were exhumed and tested, revealing the “unknown” soldier to be Air Force 1st Lt. Michael Joseph Blassie (pictured). Blassie was shot down near An Loc, Vietnam, in 1972. After his identification, Blassie’s family had him moved to Jefferson Barracks National Cemetery in St. Louis. Instead of adding another unknown soldier to the Vietnam War crypt, the crypt cover has been replaced with one bearing the inscription, “Honoring and Keeping Faith with America’s Missing Servicemen, 1958-1975.”


The Tomb was designed by architect Lorimer Rich and sculptor Thomas Hudson Jones, but the actual carving was done by the Piccirilli Brothers. Even if you don’t know them, you know their work: The brothers carved the 19-foot statue of Abraham Lincoln for the Lincoln Memorial, the lions outside of the New York Public Library, the Maine Monument in Central Park, the DuPont Circle Fountain in D.C., and much more.


Tomb Guards come from the 3rd U.S. Infantry Regiment "The Old Guard". Serving the U.S. since 1784, the Old Guard is the oldest active infantry unit in the military. They keep watch over the memorial every minute of every day, including when the cemetery is closed and in inclement weather.


Members of the Old Guard must apply for the position. If chosen, the applicant goes through an intense training period, in which they must pass tests on weapons, ceremonial steps, cadence, military bearing, uniform preparation, and orders. Although military members are known for their neat uniforms, it’s said that the Tomb Guards have the highest standards of them all. A knowledge test quizzes applicants on their memorization—including punctuation—of 35 pages on the history of the Tomb. Once they’re selected, Guards “walk the mat” in front of the Tomb for anywhere from 30 minutes to two hours, depending on the time of year and time of day. They work in 24-hour shifts, however, and when they aren’t walking the mat, they’re in the living quarters beneath it. This gives the sentinels time to complete training and prepare their uniforms, which can take up to eight hours.


The Tomb Guard badge is the least awarded badge in the Army, and the second least awarded badge in the overall military. (The first is the astronaut badge.) Tomb Guards are held to the highest standards of behavior, and can have their badge taken away for any action on or off duty that could bring disrespect to the Tomb. And that’s for the entire lifetime of the Tomb Guard, even well after his or her guarding duty is over. For the record, it seems that Tomb Guards are rarely female—only three women have held the post.


Everything the guards do is a series of 21, which alludes to the 21-gun salute. According to

The Sentinel does not execute an about face, rather they stop on the 21st step, then turn and face the Tomb for 21 seconds. They then turn to face back down the mat, change the weapon to the outside shoulder, mentally count off 21 seconds, then step off for another 21 step walk down the mat. They face the Tomb at each end of the 21 step walk for 21 seconds. The Sentinel then repeats this over and over until the Guard Change ceremony begins.