SciTech Now: Episode 616



Coming up... What's ahead for blockchain and cryptocurrencies?

Blockchain technologies are powerful, and they do have the ability to enfranchise and empower users.

...researching the chemicals in our water...

They call PFAS the forever chemicals because once they're in your body, they never leave.

...bacteria art...

I wasn't really sure what I was going to see, so I was really surprised by the diversity of the colors and the shapes.

...frogs and the environment...

So when we go out into these wetlands, we're listening to frogs and toad calls, reporting it so that we can tell how their populations are either growing or declining.

It's all ahead.

Funding for this program is made possible by...

Hello. I'm Hari Sreenivasan.

Welcome to 'SciTech Now,' our weekly program bringing you the latest breakthroughs in science and technology and innovation.

Let's get started.

Cryptocurrencies -- the best-known is Bitcoin -- are growing fast based on the underlying technology known as blockchain.

Facebook wants to offer its own cryptocurrency called Libra, and there are trading exchanges using blockchain technology doing big business.

But in a recent study, researchers found bots are exploiting these new exchanges in a very similar way to high-frequency trading on Wall Street.

Professor Ari Juels of Cornell Tech's Jacobs Technion-Cornell Institute, headed up that study, and he's here to tell us more about the risks and the possible rewards in the development of blockchain.


So, the exchanges is where these currencies are essentially traded any time somebody want to extract value or, you know, buy and sell a currency, right?

So what's so different about them than how Wall Street trades stocks?

Yeah, that's a very good question.

Cryptocurrency exchanges are places where people will trade one cryptocurrency for another.

There's somewhere they can trade things like dollars, what we would call fiat currency, for cryptocurrencies, but the particular type of exchange that we were studying is what's called the decentralized exchange.

This is a new type of exchange that runs at least partially on top of a blockchain.


The benefit is that a decentralized exchange is transparent.

The whole world can see the trades that are happening on these platforms, and the presumption has been that consequently, they enable people to interact in a way that is fair for all concerned.


What we've found is that a community of what we refer to as arbitrage bots, automated programs, are trading on these exchanges, and in some cases, they're taking advantage of users' mistakes to make a profit and, one might argue, to defraud these users.

What's an example of a mistake?

A mistake might be a typo, so for instance, you're trading a -- Say you're trading 1,000 tokens for -- of a particular type for -- Well, you want to trade 1,000 tokens for 1 Ether, which is a particular type of currency.

And instead you make a typo, and you accidentally offer to sell 10,000 of these tokens for 1 Ether.

A bot will detect the fact that you've offered this surplus of tokens for a single Ether and trade, with respect to your order, trade against your order, taking those tokens from you.

Now you may realize very quickly that you've made a mistake, but even if you try to correct it, a bot is typically going to be able to take the order you've placed faster than you.



So what's so different about this than, say, you know, what's called frontrunning in the stock markets?

Somebody basically figures out that you have an intent to sell X or Y, and they say, 'Okay.

Well, if that's what this person is willing to pay for it, well, why don't I snatch that stuff up and offer it at a different price?'

Well, certain forms of frontrunning are illegal on Wall Street.

Illegal, right.

The term frontrunning is a broad one.

The way that we use it, Wall Streeters might object to.

As I said, the thing about these decentralized exchanges is that users suppose that they're not being exposed to Wall Street-type shenanigans.


And it turns out that they are.

There are a couple of unique characteristics of decentralized exchanges.

One is the transparency that I mentioned.

Another is the fact that you can place trades more or less simultaneously.

Atomically is the term we like to use, which means you can buy with one hand and simultaneously sell with the other, and that gives arbitragers a capability that they don't have in Wall Street-type systems.

So you found in your research through these exchanges that these transactions were happening through robots that are actually costing people money in transactions?

Or, I mean, how do you value how much fraud or how much profit these bots are making?

What we've found is that to date, these bots have made about $6 million on decentralized exchanges.

That is a relatively small figure.


Dexes constitute 0.1 percent of the total trading volume of cryptocurrency exchanges in general.


There are cryptocurrency exchanges that operate off the blockchain.

That's where most of the trading happens.

And that's not transparent?

And that's not transparent, so we have really very little idea of what's happening on these platforms.

If you're not into blockchain now, why should you be concerned?

It this -- into trading cryptocurrencies, et cetera, Is this because this industry is going to gain more influence over time, and this takes away from some of the legitimacy of the currencies that are in play here?

There's an important lesson here.

Blockchain technologies are powerful, and they do have the ability to enfranchise and empower users, but they need to be used with caution, and we have to expect that exactly the same sort of cleverness, exactly the same sort of machinations that we see on Wall Street will arise, perhaps in a different form, on blockchain platforms.

The bots, technically are they doing something that is illegal?

I'm not an attorney, so I'm not going to pronounce on their legality.

What they're doing is, in many cases, pretty clearly unethical.

We've seen users plead with the bot masters in online fora, saying, you know, 'I'm a single parent.

This was a mistaken trade.

I may have to sell my car for my education.'

In one case, a gentleman from India had gathered the rupee from neighbors in his village and had lost quite a bit of money in a single trade and was pleading with the administrator or the owner of the bot to return the money.

So real people are being affected here, and clearly these behaviors are unethical.

But as I said, regulation is patchy, and it's very hard to regulate decentralized platforms, that's to say platforms that are in principle not administered by a single entity and instead running on a blockchain.

Does this make you cautious about, I guess, cryptocurrencies in general?

I mean, is it still pretty much the Wild West?

We don't have, kind of, any understanding by global governments on exactly what the rules of the road are?

Different countries, different states are all regulating it, if they are, differently?

Would you be cautious about entering this space?

Caution is certainly warranted.

As I said, blockchains are very powerful.

They can provide forms of transparency that other platforms can't, but they're not magic pixie dust.

So users and regulators and so on and so forth need to be aware of their limitations, and I think that -- That, as I said, is the most important lesson to be distilled from our studies.

It's going to take some time, I think, before governments know best how to regulate these platforms.

They have a lot of potential, and we don't want to stifle that potential.


But at the same time, malfeasance will be rampant if we don't exercise due care.

So Facebook, by the very fact that it has a couple billion potential users of their own proposed cryptocurrency, what is the likelihood that they're going to be able to avoid some of the pitfalls that you're essentially describing?

If they set up an exchange, what kinds of things can they do to make sure that this kind of malfeasance doesn't happen there?

Well, Libra is a very ambitious project, and their goal of bringing financial services to the some-odd, you know, 1.7 billion odd people who lack access to financial services is, I think, laudable.

But there are a lot of basic, unsolved technical problems surrounding Libra, and some of these relate to the challenges of fairness that I described with respect to decentralized exchanges.

But there are even more fundamental problems that need to be resolved before Libra, I think, should see the light of day.

One of these, ironically, is privacy.

If you read the Facebook white paper, the accompanying technical paper, privacy receives almost no mention, and given Facebook's lapses in its stewardship of users' data and in addressing privacy concerns, this is a notable omission.

I think they are trying to do the right thing.

The reason that I think privacy isn't treated in their existing technical documents is that we at this point really don't know how to build a cryptocurrency that offers substantial privacy and can also meet regulatory needs at the same time, and those two come into tension when you're constructing a cryptocurrency platform.

Because one of the concerns that people that are in the cryptocurrency community have is, well, if you take away these layers of privacy, and if you make me put everything in a centralized thing, you're back to almost banking again.

And that's what we wanted to try to avoid, right?

And then on the other hand, on the law enforcement side, they're saying, 'Hey, if I give you all this privacy, guess what.

You're going to have another Silk Road where you're going to be trading in horrible things, and I have no way to track who is the human trafficker or the drug dealer.'

That's absolutely right.

The need for privacy and the need to provide access to law enforcement and -- In addition to regulators so they can monitor monetary flows to ensure that this -- what promises to be a pretty big system doesn't pose a systemic threat to the world's financial system.

These things are going to require access of a type that clearly comes into conflict with privacy.

As I said, there's a tension between these two things.

We don't yet have the technical resources or, I think, the experience to figure out how the two can be harmonized in a cryptocurrency.

That is really a research problem.


Ari Juels, thanks so much.

Thank you very much, Hari.

It's a curious acronym: PFAS.

And it stands for a family of chemicals that is in most homes and being detected in an increasing number of people's water systems in Michigan and other states.

Research is only beginning to determine the effects of these chemicals.

Detroit Public Television's Great Lakes Bureau has the story.

PFAS: They're in you.

They're in me.

They're even in polar bears in the Arctic.

You can find PFAS in pizza boxes, Gore-tex, Teflon pans, cosmetics, fire retardants and cleaning products.

You can find them in the workplace.

They're in your food.

They're in your drinking water.

They call PFAS the forever chemicals because once they're in your body, they never leave.

But what are they?

They're complicated.

They're part of a group of human-made chemicals referred to as emerging contaminants.

So what can PFAS do to you?

Well, scientists say high levels of the chemicals have been linked to kidney and testicular cancer, high cholesterol levels, thyroid and colon problems and fertility problems.

PFAS has been around to 70 years.

Dupont created Teflon.

Then 3M invented Scotchgard.

Now PFAS is in everything from drinking water to food and particles in the air.

A couple of cases of PFAS contamination hit West Virginia.

Two decades ago, PFAS were connected to the deaths of 100 cows and the contamination of drinking water in Parkersburg.

On the other side of the state, firefighting foam used by the National Guard led to the contamination of the drinking water in Martinsburg.

In west Michigan in 2017, a shoe company's use of Scotchgard has been blamed for polluting the city of Rockford's water supply.

Some of the wells had PFAS levels nearly 600 times more toxic than what the Environmental Protection Agency said was safe.

This led Michigan governor Rick Snyder to create a PFAS task force to look at water supplies all across the state.

Now that's more than 1,300 water systems in 460 school districts.

All this has led to the discovery of more high levels of PFAS, and now there's a state of emergency in two townships near Kalamazoo and a preschool in Ionia, near Grand Rapids.

The governor issued a 'do not drink the water' emergency and opened up emergency centers to hand out bottled water.

High PFAS levels are now reported in Lake St. Clair near Detroit where Selfridge Air Force Base is the source.

There's also a 'do not eat fish' advisory for three counties near Detroit after PFAS was discovered in the Huron River.

The Michigan Department of Environmental Quality says there are at least 35 confirmed PFAS contamination sites in Michigan with possibly 11,000 more, and this could be just the beginning of what's happening all over the U.S.

So what now?

Well, PFAS doesn't fall under the federal Safe Drinking Water Act.

Environmentalists says the EPA needs to step in to take some sort of action.

One thing is sure.

Right now the drinking water supply for 9 million Michigan residents and maybe millions of people all across the world is at risk from PFAS contamination.

I'm Mary Ellen Geist, Bureau Chief at Detroit Public Television's Great Lakes Bureau:

♪♪ ♪♪

Typographer and illustrator Craig Ward heard an urban legend that 'Using the hand rails on a subway is like shaking hands with 100 people.'

He decided to test that theory by sampling the bacteria on subway lines around New York City and photographing his findings.

Our partner, 'Science Friday,' has the story.

There's the urban legend that when you use the handrails on the subway, you're effectively shaking hands with 100 people at the same time.

I wanted to see if there was any way to kind of capture that.

My name is Craig Ward, and I'm a typographer and designer based here in Brooklyn.

My work tends to be a mix of typography and photography and illustration.

I try and work with people from a lot of different areas intentionally.

There's immunologists and biochemists.

I had seen a photograph from a researcher of her 8-year-old son's handprint in an agar dish.

Obviously working with type a lot, I've started to think about letters of the subway lines and decided to bring those two worlds together.

I mean, you can get away with most things on the New York subway, but I feel like as soon as you start getting out scientific equipment, people, you know, want to raise their eyebrows and maybe shuffle down the seat a little bit, which is crazy considering the stuff you do deal with on the subway.

I would just try and get it done as quickly as possible.

It was a little uncomfortable.

I just sort of kept them dark and warm for up to a week.

I wasn't really sure what I was going to see, so I was really surprised by the diversity of the colors and the shapes.

It felt like I needed to juxtapose the, you know, the grossness of it and sort of present it in quite a premium way.

I wanted to tie it back to the subway lines themselves, so I used the colored gels.

They look like little worlds, you know?

I think that's what I really like about them.

People began to ask me what I've actually captured.

You could probably safely identify around a dozen or so different kinds of bacteria.

Anything else would probably have needed to, you know, be isolated and sent to a lab and tested properly.

I think probably two-thirds of what we found were what's deemed natural flora, which is, you know, present on everybody's hands.

We did find some creepier stuff: salmonella in small quantities, E. coli, staph, strep.

The Weill Cornell Pathomap Project, that was next-level.

They basically swabbed every subway station around the city, over 400 stations, and profiled something like 15,000 species of bacteria, almost half of which had never been seen before or never been identified before, which is obviously super creepy.

I reached out to them, just sort of to compare notes.

I think that's sort of pretty much in line with what I found.

Alongside the creepy stuff, I think it's great that they were able to isolate bacteria sort of associated with mozzarella and sauerkraut.

I think, you know, New York is such a foodie city.

I think it's perfect that that's what you find in the subway as well.

I think the images are portraits, albeit very unconventional ones and not, you know, certainly not in the traditional sense.

They're very much a snapshot of the people of New York and commuters.

The subway, as rife as it is with bacteria, isn't a hospitable environment for the bacteria, so if I hadn't captured it on that particular day, it would have been dead within hours or a day or so at most.

I think there's an element of truth to the myth about the shaking hands with 100 people.

I feel very small here, where there's -- Just be happy about the fact that there's a lot of smaller individuals just sort of struggling with New York on your train as well as you.


All waves transfer energy, but the way they do it varies.

A longitudinal wave can carry energy through air, water and solids, and it does it by compressing and expanding the medium in the same direction it transfers the energy.

This compression and expansion can be measured in different ways.

A compression is a point where the medium is at its most squished, or maximum density.

A rarefaction is a point where the medium is most spread out, or least dense.

Amplification is the measurement of how far the particles are pushed from their resting state, and the wavelength is the length of one wave cycle, compression to compression or rarefaction to rarefaction.

Longitudinal waves use particles to push the energy.

That means they can travel through gas, liquids and solids, but not through a vacuum.

Sound is a longitudinal wave, for instance, and there is no sound in space.

Feel that beat?

That is a longitudinal wave.

♪♪ ♪♪

FrogWatch USA is helping citizen-scientists young and old understand the significance of frogs as an indicator of environmental health.

The FrogWatch database will help scientists better understand where these key indicator species are thriving or failing.

We learn more in this segment from PBS News Hour's Student Reporting Labs.

Going on the FrogWatch monitoring sessions is always a bit of an adventure because you never really know what you're going to experience and what you're going to discover as you collect your data.

My name is Sonya Dunham, and I am a FrogWatcher in Greenville, South Carolina, and I do it with my daughter Elsa, my 10-year-old daughter.

My name is Jennifer Garcia.

I am the education program coordinator at the Greenville Zoo.

FrogWatch USA is one of the flagship citizen science programs of the Association of Zoos and Aquariums, or AZA, and AZA helped to start this FrogWatch citizen science so that we can monitor the breeding habits of Anurans, which are frogs and toads.

So when we go out into these wetlands, we're listening to frogs and toad calls, reporting it so that we can tell how their populations are either growing or declining.

My name is Hugh Vant-Levon.

Frogs and toads are indicators of what's going on in the environment.

They give us a heads-up.

They're a first shot that there's changes taking place, and are these changes good or are they bad?

When our frogs disappear -- there's 30 percent of them in the United States that are on the list for disappearing completely -- we need to be monitoring that and making changes and adjustments so that that doesn't happen because these are on the food chain, you know?

They may not be at the bottom of the food chain, but they're down there.

And so what happens to them affects people farther up the food chain.

All of that is going to impact us at some point in time.

We need to recognize that and to act on that.

So after about 30 minutes past sunset, we follow a procedure where for 2 minutes we need everything to be quiet, and if anything interrupts that silence, we have to stop and start the 2 minutes over again.

And then, but once we get 2 minutes of silence, then we monitor for 3 minutes, and basically we cup our hands around our ears so we can listen a little better because it helps with the acoustics.

And we just, very, very quiet, we stay quiet and just really listen and pay attention to any of the frog calls we might be hearing.

As soon as that 3 minutes is over, then we whip out our flashlights and record everything that we heard: the different species, and there's a scale about how many, if there's just one individual or a full chorus, and all the information like that.

So when we go to monitor frogs, it's usually group of us, sometimes a small group, sometimes maybe a little larger.

What's special about building those relationships is, you're not just learning about frogs, but you're also getting to learn more about their specialties.

It's a really great way for families to connect with each other and to have a weekly activity where they go out in nature and spend some quality time together.

So one of the reasons I really appreciate and enjoy participating in FrogWatch as a citizen science project is, it's something I do get to do with my daughter, my 10-year-old.

She loves reptiles and amphibians, and so to be able to encourage her in that...

If you immerse somebody in a dusk-filled park and all the cacophony of noises starts -- You know, you hear these frogs.

You hear an owl.

You hear splashes of the wetland nearby.

It's senses that are awakened, and it really creates a memory that you're not going to forget.

Is FrogWatch beneficial?


This is a good way to monitor changes in the environment.

It's a great way to not only just learn more about the frog species in the area but to expose yourself or your family to what it means to be involved in science and to the detail involved in how to just be quiet and pay attention in nature, and not just rush through, like -- Our lives are so busy nowadays, so it kind of forces you to come to a pause and just be quiet and listen and notice what you're hearing.

If we don't take care of our facilities, our country, our climate and our world, this affects the young people.

It affects old people.

It affects everybody and everything.

It's our world.

It's the only one we've got.

We need to take care of it.

And that wraps it up for this time.

For more on science, technology and innovation, visit our website.

Check us out on Facebook and Instagram, and join the conversation on Twitter.

You can also subscribe to our YouTube channel.

Until then, I'm Hari Sreenivasan.

Thanks for watching.

Funding for this program is made possible by... ♪♪ ♪♪ ♪♪ ♪♪