SciTech Now Episode 335

In this episode of SciTech Now, the Cahokia State Historic Site in Illinois is using new technology to unearth an ancient city; a team at Carnegie Mellon University is creating the next generation of wearable electronics; a look into a mighty marine microbe; and the white-nose syndrome that’s hitting west coast bats.



Coming up, using new technology to unearth an ancient city.

There are a lot of questions we have about Cahokia and what happened here, and through, you know, controlled excavations, we hope to answer a lot of those questions.

The next generation of wearable electronics.

You know, the rubber film and the electronics are just so soft and thin that they can just stick to your skin, you know, almost like a Band-Aid.

A mighty marine microbe.

Its early ancestors were among the first photosynthetic cells on the planet.

White-nose syndrome hits West Coast bats.

We have seen populations of bats in eastern colonies decline in some cases to 100%.

It's all ahead.

Funding for this program is made possible by the Corporation for Public Broadcasting, Sue and Edgar Wachenheim III, and contributions to this station.

Hello. I'm Hari Sreenivasan.

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

Let's get started.

Archaeologists are using modern technology to probe a historic city.

St. Louis reporter Jim Kirchherr takes us to Cahokia State historic site in Illinois, where recent excavations have revealed secrets about ancient civilizations.

Let's take a look.

They start showing up just after 5:00 a.m.

at the reconstructed circle of posts called Woodhenge at the ancient city known today as Cahokia Mounds.

This is the first day of summer.

That's why they've come.

Just to celebrate the solstice the same way that the old people used to.

Just something we wanted to do before we pass on.

The man with the stepladder is Bill Iseminger, site manager of the Cahokia Mounds State Historic Site.

He gives a talk here every solstice and equinox at this solar calendar built to mark the seasons and the rising sun.

First of all, for those who are not that familiar with our site, this is the largest prehistoric Indian settlement in America, the largest north of Mexico.

We'll see kind of the glow of the sun.

We may not see the actual ball of the sun because of the trees that have grown up.

And about 60 people showed up for this 5:20 sunrise.

It's likely a lot more than that witnessed the sunrise at this place a thousand years ago.

So we use the term city when we talk about Cahokia because it was so much bigger than anything else at that time or even for a long time after that.

It covered about 6 square miles, had about 120 mounds here, and at its peak, maybe anywhere from 10,000 to 20,000 people.

The excavations that have gone on at this site over the years, if you put them all together, probably less than 1% of the site has been excavated.

But when you think about how big the site is...

There are a lot of mysteries in this place.

This Mississippian metropolis was abandoned long before European explorers arrived to discover one giant earthen mound and many smaller ones.

Over time, some of the mounds were destroyed.

Artifacts were taken.

Fields were plowed.

Roads and highways and subdivisions were built.

Serious site preservation and archaeological study really didn't get under way here until the 1960's.

And now every year you'll find archaeological teams digging, searching, putting together the pieces of a very large and complex physical, social, and political puzzle with no written or direct oral history to guide them.

It is steady work.

Well, my eyes are always just searching the landscape.

John Kelly has been digging here for nearly 50 years.

So from basically early '60s and up to today working here, and there are other institutions, there's been continuous work.

I wouldn't say, there's probably hasn't been a year in which there hasn't been some kind of excavations being done at the site.

And the knowledge has given us a much clearer picture of this city -- the physical layout, the structures, the neighborhoods -- and the people from the great chief on the big mound to those who lived and worked throughout the city.

And yet there's so much more to find, and there are new ways to find it.

A team funded by the National Geographic Society was here surveying a field near the big mound with a magnetometer, which will indicate features below ground where soil has been disturbed, say, for the building of a house or a sweat lodge.

And this technology will basically pick up differences in magnetic properties to see where humans were altering the soils.

We can also use techniques like ground-penetrating radar, or GPR.

We did do a small section earlier this week of GPR.

At another dig directed by St. Louis University professor Mary Vermilion, they did an electrical resistance survey.

Probes run a current through the ground, and variations in electrical resistance produce a map and a pretty good idea of where you should dig.

This is the sweat lodge.


So that's pretty spectacular.

You can see it's 3 meters in diameter.

How much of this kind of technology is changing what archaeologists do and how they do it?

It's changing it drastically.

And now more and more before we start excavating, to be able to help us place where excavation units are, to save time, to save labor.

Archaeologists still use shovels and trowels and brushes, but they can now look into the ground before they dig.

But go around this little corner here.

John Kelly for years has been concentrating on mapping the stockade wall that once enclosed the big mound and its plazas.

But I think the most important thing for me as an archaeologist is actually seeing the way in which communities were laid out, but also how that space relates to their cosmology.

More than likely, the leader on top was thought to be related to or brother of the sun.

To have the sky brother coming out of his mound would reinforce his authority and power and his connection with the upper world.

There are a lot of questions we have about Cahokia and what happened here.

And through, you know, controlled excavations, we hope to answer a lot of those questions.


From smart watches to Bluetooth shoes, electronic wearable devices have exploded in popularity.

Now engineers are working to create lighter, thinner, and more efficient electronics.

One team at Carnegie Mellon University has even created a printable smart tattoo that can monitor body functions.

Carmel Majidi, an associate professor of mechanical engineering at Carnegie Mellon University, joins me now to talk about this breakthrough.

So first of all, what is a soft machine?

Because what you're describing in electronics that are kind of bendable and wearable, how do you do that?

So, number one, thanks for having me over.

And so the work I'm going to show, this is from my research group, the Integrated Soft Materials Lab, and there's a few different approaches to engineering machines and electronics that are soft, stretchable, bendable, compatible with the body.

Just brought a few examples here just so you have a sense of the types of materials that we work with.

So this is based more on a conventional flex circuit technology, and so this circuit is actually designed from measuring muscle activity.


And so on the bottom side here you see these electrodes that make contact with the skin.

As your muscle contracts, it generates electrical signals.

That gets picked up by the electrodes, and then the signals are processed by these electronics on the other side.

So this is just one approach.

I mean, you can tell it's pretty thin.

It's flexible.

It conforms nicely to the skin.

But, I mean, you asked about, you know, soft and, you know, stretchable electronics.

Effectively what we would really like to have is something more like a second skin.

And for that there's a few different approaches that my group has been looking at.

One approach incorporates insulating and conductive rubbers.

So here's an example of the same muscle-monitoring circuit, but now instead of these thin copper traces, we have these conductive rubber composites.

Another approach uses liquid metal.

This is a nontoxic mixture of gallium and indium.

The alloy has similar conductivity than what you get with conventional wiring.

But it's liquid, so it deforms with the surrounding rubber.

The circuit remains intact as we stretch.

So there's been a lot of progress in the space of manufacturing and materials for these soft stretchable electronics and machines.

So what's it going to, you know, when you get, you get kind of thinner and thinner.

When you get down to liquid metal, and we talked about this idea of almost a tattoo, I mean, you're putting that tattoo into that rubber, right?




And so the idea is that the, you know, the rubber film and the electronics are just so soft and thin that they can just stick to your skin, you know, almost like a Band-Aid, or if you will, like a smart tattoo, or at least that's the, that's the vision.

And, you know, eventually where we'd like to go with this, I mean, not just talking about electronics on your skin but potentially also in implants.

And how would that work?

So the thinking, so, I mean, you know, already, I mean, we have, say, pacemakers and defibrillators.

I mean, these go in the body.

I mean, they play a, you know, a vital role for example in preventing cardiac arrest.

The, one of the challenges, though, with these are they typically depend on fairly rigid and then bulky electronics.

And so the thinking is if we can take some of these same soft and stretchable electronics and incorporate that into these medical implantables, then we can have implants that are more compatible with the surrounding tissue and organs.

And they could probably send you more information back.


I mean, so --

Because right now, sometimes people think of implantables as almost dumb objects.

They're pumps to do one specific thing over and over again until they run down.


And they're in limited parts of the body or just even, you know, wearables in general.

I mean, when we think about, say, sensors in your smart phone or an activity tracker in a smart watch, I mean, there's only so much, right, that you can learn from having a sensor, say, in your pocket or on your wrist.

By having electronics that are kind of soft, have this kind of second skin type functionality, we can place them on different parts of the body.

We can put them, implant them in various locations so we can get a much richer picture of your physiological state.

So when you go work out, this could just be a sensor that's embedded in your shirt that's monitoring your heart rate?



So it could be embedded in the clothing.

It could stick to your skin.

It could monitor heart rate, muscle activity, oxygen in your blood.

I mean, all sorts of different types of vitals that would otherwise be very difficult to access with existing wearables.

In this process, have you had to design how you actually print these things into existence?

Because probably not too many printers can do what you're talking about.


So a lot of the manufacturing techniques with these conductive rubbers and these metals are going to be different than what we use for traditional flex and rigid circuit.

So a lot of the research, a lot of the work in my group and others at Carnegie Mellon and elsewhere, I mean, has focused on novel printing techniques for patterning these circuits.

Another challenge is also interfacing these soft, stretchable circuits with the pins of these rigid microchips, so --

This isn't something that a 3D printer at home is ever going to be able to do?

Or maybe...?

Well, you know, potentially maybe.

I mean, we're actually, you know, looking right now at ways of retrofitting 3D printers so they can print conductive rubber composites or this liquid metal alloys.

And so, no, it could be possible in a few years.

So best-case scenario, ten years from now, if there are applications of this sort of soft, wearable electronics in the marketplace, how would life be different?

How do you see somebody interacting with this?


Well, like I said, I mean, you know, one is in the space of wearable computing and biomonitoring.

And another potential application and, you know, something that, you know, we're very excited about is the potential for using these in robotics.

I mean, you an almost think about these materials as being artificial skin, artificial nervous tissue that could be used to make robots safer for physical interaction, a little bit more natural to the touch.

I mean, when we think about, you know, robots and the robot revolution, I mean, oftentimes you picture a humanoid that's working in close proximity with humans, and so physical contact is going to be inevitable.

And so we do have to be mindful of the types of materials that we use that construct these machines.

I mean, better to be in contact with kind of a soft, rubbery robot as opposed to a machine built from hard plastics and metals.


Carmel Majidi, associate professor of mechanical engineering at Carnegie Mellon.

Thanks for joining us.

All right.

Thank you.

It was a pleasure.

Up next, it's one of the most abundant photosynthetic organisms on earth, but you may never have heard of it.

Prochlorococcus is a tiny plantlike bacteria, which is responsible for about 5% of all photosynthesis on the planet.

My next guest was part of the group that discovered the marine microorganism almost 30 years ago, and her lab is dedicated to studying the organism today.

Penny Chisholm is an institute professor at the Massachusetts Institute of Technology.

Thanks for joining me via Google Hangouts.

So, first of all, how is it possible that a tiny microbe like this could be responsible for 5% of an enormous process on the planet?

It's very small, but it's incredibly abundant.

Throughout the oceans, the mid-latitude oceans, it's the most abundant photosynthetic cell in the ocean.

So it contributes a significant fraction of ocean photosynthesis.

And this is in the ecosystem regardless of which part of the mid-ocean that you go to?


We pretty much find it everywhere except in some places along the coast.

It doesn't... It likes to grow in the open ocean, very pristine open ocean waters that are relatively warm.

We don't find them in the high latitudes.

So this is both key in what?

The food chain as well as oxygen production?


It's the base of the food web in these regions, and it's producing significant quantities of oxygen and taking up carbon dioxide in photosynthesis.

How old do we think this is?

Not just the... The process is forever, but how old do we know, do we have any kind of carbon dating that puts this particular microbe in history?

Its ancestors are incredibly ancient.

Its early ancestors were among the first photosynthetic cells on the planet.

After life evolved, they were the ones that actually put oxygen in our atmosphere.

But Prochlorococcus itself is actually very recent in terms of the evolution of microbes.

So if there is so much of this, is there a risk ever of too much?

I mean, in terms of, you know, people are familiar with algae blooms.

It's totally different, but are there particular areas of the ocean where there's an abundance of them versus other areas where they're more necessary?

That's what's so interesting about Prochlorococcus.

Where it is, it's fairly stable in abundance.

It grows.

It doubles about once every day.

The cells divide in half.

That's how it multiplies.

But it gets eaten just as fast as it grows.

So the actual numbers stay fairly steady wherever it is.

So it isn't one of these bloom-forming species like we see in coastal waters.

It's very finely tuned for the niche where it lives, and it stays at these very stable numbers.

And what's it like when it comes to genetic variation?

And how does that play into the success of its species?

That's one of the most amazing things that we've learned over the last 20 years since genomics has become a tool that we could use.

Each strain, or each individual cell, has about 2,000 genes.

But every time we look at another strain or another lineage, we find that it has maybe 100 or 200 genes that haven't seen before.

So there's extraordinary diversity in the, we call it the Prochlorococcus collective, such that if you... so far the estimates are if you took all of the Prochlorococcus genes in the oceans, there's probably up to 80,000 unique genes in that collective -- whereas our human genome is only 20,000 genes.

So there's more diversity of function in all the Prochlorococcus together than there is in our human, our complex human metabolism.

So does that give us an indication that perhaps that these are adapted to their specific environment really well, meaning that could you take one and plant it in a different type of ocean?

Would it survive or thrive or would it say, 'Well, the conditions are a little different here,' and it would just go away?

Excellent question.

And that's basically what we've been studying all these years, is looking at how these different, we call them ecotypes, are distributed along different gradients in the ocean.

So there are some that are adapted to high light intensities and others that are adapted to low light intensities that you'd find deep in the water column.

And they're so different that light intensities that are optimal for one strain would actually kill a different one.

And we see the same thing for temperature.

There are some that are much better adapted to the lower temperatures at the high latitudes than along the equator and others that are adapted to the equatorial regions.

So the range of environments that the collective can thrive in is much, much broader than any individual strain.

Could we use them in any sort of an intervention?

Meaning if there are spaces in the ocean which are becoming hypoxic or in low oxygen levels, could you take some of these, put them in there, and get them to be producing oxygen?

We don't think of it in that way because they are so finely tuned for their particular environment, although it's interesting you should ask that question because there are some regions in the oceans that are very low oxygen that are dominated by Prochlorococcus.

And we don't know why they're in the deep, deep layers of the low-light layers of the oceans, and we're actively trying to understand what it is.

The trouble is these environments are complex, so a cell could be dominant because its predators aren't there or it could be dominant because it's perfectly adapted to the chemistry or temperature of that water.

And so you have to study the food web in order to really get to the bottom of what's causing those patterns.

All right.

Penny Chisholm of MIT.

Thanks so much for joining us.

Thank you very much.


In 2006, millions of bats began dying of a mysterious disease called white-nose syndrome.

For years the disease was confined to the northeastern United States, but now the deadly disease has spread to bats in the Northwest.

And the Washington Department of Fish and Wildlife is racing to stop a white-nose outbreak in the bat population there.

Our environmental reporting partner, Earthfx, has the story.

Ready for the sampling?

Yep. Ready.

Wildlife veterinarian John Huckabee is on the lookout for symptoms of a deadly and contagious disease, a disease that kills bats by the millions.

There are a few deep-pigmented areas of scarring.

But overall, looks like he's in very good shape.

This silver-haired bat doesn't seem to be a carrier.

But a few months ago, a little brown bat arrived at his office outside Seattle.

I saw that one of the wings had a lot of contracture and some wounds, some lesions on the wing.

And it had an appearance like it may have a fungal infection.

The odd scarring was a possible sign of white-nose syndrome, one of the deadliest wildlife diseases in modern times.

First discovered in New York state in 2006, white-nose syndrome has killed more than 5 1/2 million bats and counting.

The disease, which is spread primarily from bat-to-bat contact, has wreaked havoc on the large colonies of the East Coast.

We have seen populations of bats in eastern colonies decline in some cases to 100%.

Until recently, it wasn't known how the disease killed its victims.

But new research suggests that bats with white-nose wake up more often during hibernation.

This causes them to burn through fat reserves that would usually sustain them through the winter.

Starvation and death soon follow.

In just a few short years, the epidemic raced across the country, spreading from the Northeast all the way to Nebraska and Oklahoma.

But then it hit an enormous natural barrier.

The Rocky Mountains kept the disease from reaching western bats, or so scientists thought until Huckabee's discovery.

Some speculate that an infected bat may have hitched a ride on a freight truck.

Others think hikers or cavers may have unwittingly carried the fungus on their clothes or equipment.

Since the first infected bat was found in the forest east of Seattle, the white-nose fungus has been found twice more in Washington state, both near the original site around North Bend.

Good job.

We have bats in the net.

Fear of a white-nose outbreak has jump-started research, not just in Washington, but around the Northwest.

In Central Oregon, ecologist Tom Rodhouse and a team of researchers are collecting data on local bats.

Bats hang out in the dark.

They hang out in these big cliffs and crevices that we can't access.

So we've gone for decades without really understanding what's happening with bats.

Was it coming out?

They're trying to assess the health and population size of Oregon's 15 species of bats.

There's really no way for us to ascertain what's happening with our bat populations without this kind of a coordinated, large-scale survey effort.

I'll grab the detector.

Back in Washington, researchers such as Abby Tobin are trying to learn how bats spend their winters.

We're trying to figure out what type of habitats they're roosting in, if they're hibernating through the winter or if they are kind of active throughout, and also looking at those habitats they're using and whether the environment there is conducive for the fungus to thrive.

Why don't we kind of go down a little bit to be away from the trail?

It would be a little more stable.


Let's try down there.

She's setting up bat detectors, specialized microphones that can pick up bats' high-frequency calls.

Yeah, that's good.

Oh, yeah.

Each bat has unique echolocation call, and so we're able to identify them based on that call from those acoustic detectors.

Now I got to turn the detector on.

From this I could tell this is a canyon bat.

And they have this typical kind of hockey-stick shape look to their call.

In the lab, Tobin looks for small signs the disease is taking hold in Washington.

There's a couple little, tiny little holes.

I am looking right now to see if there's any damage to the wing membranes, which would be a sign that it had white-nose syndrome.

It's important to detect white-nose syndrome early because it allows us to get a sense of where it is, so we might be able to do some sort of containment or treatment with the animals.

Despite white-nose's deadly effects on bats, it poses no known threat to people.

But many questions remain.

And it could be years before definitive answers emerge.

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 next time, I'm Hari Sreenivasan.

Thanks for watching.

Funding for this program is made possible by the Corporation for Public Broadcasting, Sue and Edgar Wachenheim III, and contributions to this station.