SciTech Now Episode 435

In this episode of SciTech Now, we take a look at how bats can advance human technology; Ainissa Ramirez discusses if there are genetic markers for concussions; understanding how surface water and groundwater interact and the dangerous reality of mudslides.


[ Theme music plays ]

Coming up... A bat's swift flight...

We're really interested now in how the animal has evolved to generate these kinds of forces and motions.

What can we learn about thrust, about lift, about unsteady flight mechanisms?

...what our genes say about us...

They can say, 'Okay, well, you may have more concussions because you have this gene.'

...a tale of two waters...

The concern is whether there's going to be any impact from future water-resource decisions.

...the dangerous reality of mudslides.

Enough material came out of the canyons to fill, perhaps, 300 football fields.

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, technology, and innovation.

Let's get started.

Bats are known for their bony wings and fast flight.

Researchers at Brown University in Rhode Island are studying these characteristics to determine how bats can advance human technology.

Our partner 'Science Friday' has the story.

Before we had high-speed video, people had this view that bat flight was just kind of a minor variant of bird flight.

But what we've found over and over again is how unbelievably maneuverable these animals are.

Being able to manipulate their wings and their bodies in such a way that they can adjust and they can maneuver really boggles the mind.

A bat wing, framed by the skeleton, allows bats to have a kind of control over a three-dimensional shape that would be impossible for any other kind of flying animal.

I'm Sharon Swartz.

I study bats, how they fly, and the structure of their wings.

And I'm Kenny Breuer.

I'm a professor of engineering, and I study animal flight and fluid mechanics.

So, the collaboration between Sharon's lab and my lab allows us to approach the same problem from two different perspectives.

We really find that we can do much more interesting things together than either of us can do by ourselves.

Because we're able to combine aerodynamics with the study of the morphology of the wings.

There's a lot of really fundamental differences between the flight of birds and bats.

So, a bird wing is a relatively stiff airfoil.

Bats have a whole hand in their wing, and that allows them to change the conformation and shape of the wing with incredible dexterity and precision.

So, the bones of the part of the wing that's closest to the shoulder, the humerus and the radius, have the kind of geometry that we see in birds.

But once you cross the wrist joint, we see bones that are less mineralized, and that makes that bone itself less stiff.

It actually promotes bending.

We don't usually think of skin as being a muscular organ, but the skin of the wing membranes of bats is invested with a whole series of muscles.

And what we observe is that the muscles turn on and off in every wingbeat cycle.

And so these muscles can change the stiffness of the skin in the wing membrane.

And so that means the muscles change the aerodynamic properties of the airfoil.

And that's completely different from a bird in the way in which it operates.

It bends, it flexes, it puffs out.

So, they're able to continue to generate lift even as they're moving more slowly.

So, when we first started, really very little was known about the precise nature of bat flight.

We're really interested now in how the animal has evolved to generate these kinds of forces and motions.

What can we learn about thrust, about lift, about unsteady flight mechanisms, about muscle activity?

And we design these experiments at each stage just to move ourselves forward.

So, when we do our tests, we use two facilities.

One is a flight corridor, which is just a room, and we have our cameras set up in there.

Just being able to see in detail how bats move their wings has turned out to give us a lot of insight.

The other one is this wind tunnel.

The equivalent of a treadmill for a flying animal.

We take high-resolution, high-frequency motion of the wings from multiple angles, and we reconstruct the kinematics of the motion that way.

And then we fill the wind tunnel with a cloud, and we record the motion of the particles of that cloud, and from that, we can reconstruct the wake.

And that lets us learn a lot about how it uses the wings to produce aerodynamic forces.

Once we've taken measurements with the animals, we can re-create aspects of that using engineered robotic flapping wings that we test in the wind tunnel.

And there, we can do things that we can't ask the animals to do, and it does provide a lot of inspiration and ideas of things that we might try for building robotic flying vehicles.

So, one of the things that bats do extremely well is landing.

They have to slow down, they have to flip themselves upside down and land, hanging on to the ceiling or hanging on to a tree roost.

It's like doing a high dive backwards.

What we've found is that, during the last two wingbeats of a bat preparing to land, there's almost no aerodynamic force produced.

They also use the mass in their wings to manipulate their body, and that controls their rotation in the same way that a high diver controls her rotation when they dive.

The bats are incredibly agile and maneuverable, and they're very resistant to perturbations in the air -- to gusts.

If we want to understand how bats are able to do this so well, we have to have some way of providing a gust to the animal in the lab and then seeing what it does in detail.

We have two sets of laser crossbeams here so that when the bat flies through, the bat breaks the laser beams.

That sends a trigger signal.

The air jet delivers a puff of air, and we can capture all of that in high-speed video from above and below using an array of high-speed cameras.

We find that, even really strong gusts of wind, they recover stability in less than a single wingbeat.

And so what we're trying to understand now is, what are the mechanisms that they use to recover so quickly?

What is it about the properties of the body and the wing that might return control passively, and how much is active?

The ability to do these experiments really gives us a unique insight as to how these animals move and maneuver, and also just how they evolved.

I mean, what is the evolution of flight in mammals?

I think that we understand enough now about how flight works where we can look at the origin and diversification of that flight.

It's a beautiful evolutionary laboratory.

I love those moments where you've recorded something that no one has seen before.

A moment of insight into the natural world.

It doesn't matter how tiny it is.

There's nothing like that.

Ainissa Ramirez is a scientist, author, and a self-proclaimed science evangelist.

She is the creator of a podcast series called 'Science Underground.'

She joins me now to discuss if there are genetic markers for concussions.

This is an important topic.

A lot of people have been thinking about it, not just in the context of NFL players, but also now little-league soccer kids and lots of things.

Is there something in us that makes us sort of worse off if we get a concussion?

Well, it's still early on in the research in terms of the genes.

They have been able to identify some things.

The first thing we need to do is, we need to understand what a concussion is.

So, the brain hits the inside of the skull.

And what happens is that the brain cells, the neurons, they act erratically, and they send electrical chemicals going in one direction in another.

So, we can examine the different types of genes that look at or modify those signals.

That's the first thing that they do.

The other thing we can do is, we can look at the genes and see how well they repair, and that's the smoking gun that they've found.

They found a gene called the APOE that -- it seems to change how fast, or it slows down how fast it will repair.

And that seems to be the smoking gun.

They see that, if you have this certain variant of APOE, that you have a tendency for concussions more readily than other people.

So, somewhere in the future, are we gonna be having genetic tests on babies or little children, and we tell their parents, 'Okay, they have this thing.

Make sure they wear a helmet every time they ride a bicycle.'

Or how does it work?

I think that that will be on the horizon fairly soon.

And, again, it's susceptibility.

It's not a deterministic.

And what that means is that you are more inclined, you have a proclivity for concussions, but that doesn't mean you're gonna get it.

They just see the linkages.

And, again, the research is still very early.

So, that information is useful if you have a son or daughter who's interested in a sport where there's some kind of impact.

You can get the test and realize, 'Okay, well, you know, this person shouldn't be having hard impacts during practice all the time.'

It gives you some information of how to modify your practice schedule.

Well, what do we do with this information for people who have already had concussions?

Mm. They can say, 'Okay, well, you may have more concussions because you have this gene, and because the brain cells are not able to repair as quickly.'

But it doesn't really do anything in terms of the symptoms.

It's just giving you information that this might happen.

Even if we could put helmets on players that detect exactly what kind of force they've been hit by, there's still a big cultural hurtle we have to overcome, to say, 'Okay, this is actually good information that you should have, and you should be making these kinds of decisions with it.'

You know, because say, for example -- part of the problem at the NFL level or college-football level is, college athlete might not want to put this on, because if it looks like they have two strikes against them, then a team might not draft that guy.


You raise a good question.

The information is good, but also it's in a context.

Who knows? If you're a football player and they find that you have this gene, your coverage, your health coverage might change.

So you have to be careful about privacy issues and the like.

So there's a lot of things.

So, scientists are just looking to see what causes a concussion, and what prevents people from healing.

That's one part.

But putting it in a context about how we change practice schedules, if you will get drafted, those are the consequences as a result of that information.

All right.

Ainissa Ramirez. Thanks so much.

Thank you.

A geoscience team from the Southwest Research Institute in San Antonio, Texas, is using computer modeling in an effort to understand how surface water and groundwater interact.

Here's a look.

Well, the problem is that Texas is in a semi-arid area, particularly the western part, and there are increased demands for the water.

Limited resources.

And so it's become very important to understand the relationship between surface water, groundwater, the demands, river flows, spring flows.

And we've been working on different studies in order to look at that.

In particular, we've just finished a study on the Devils River, which is in a very challenging area because of the limited amount of precipitation and the demands that are being placed upon those water resources.

This is a map of South Central Texas.

And what we are showing are the different watersheds.

Some go off into the Colorado River, off into East Texas.

The rest of those funnel down to the Rio Grande.

And what you see is, at the center of this image is the Devils River.

You see the Lower Pecos.

And if you look at all the water that is discharged out of Amistad Reservoir, about 1/3 of it is recharged out of Val Verde County.

And most of that comes out of Devils River.

So even though the Devils River watershed looks rather small relative to some of these other watersheds, it provides 15% to 20% of all the water in the lower Rio Grande.

Green provides an interesting graphic to demonstrate the region's relationship between rock and the flow paths of groundwater.

An easy way to visualize this is, think of it as pipes in a sponge.

So, the rock is the sponge.

These preferential flow paths are pipes.

So, we've placed them along some of the major tributaries in the Devils River, as shown in this graphic.

So if you happen to put in a well that's close to one of these pipes, you're going to do very well.

If you happen to put in a well away from the pipes, you're going to be lucky to get a few gallons a minute.

And so that's what this graphic shows.

It's pipes in a sponge.

But what happens when too many wells are pumping water from the ground in the area?

The concern is whether there's going to be any impact from future water-resource decisions.

And by that I mean, there are some thoughts of maybe putting in some well fields in order to intercept some of that groundwater and use it wherever the need may be.

It may be locally.

It may be at some distance, where they'd need pipelines.

The concern is, at what point does that groundwater pumping impact the river?

And that's a hard question to answer.

We've been working on it since about 2009.

And we've made some progress in the last few years, and we did that by developing a groundwater model, a computer model, and a surface-water model.

But we base that on a lot of underground work.

We've looked at the chemistry of the water.

That tells you a lot about where the groundwater goes, how it flows.

We've done sub-surface imaging using geophysics, where we try to understand what the rock looks like, particularly near the rivers.

We've looked at the hydraulics, which is the capacity of wells in the area.

Green and other scientists at Southwest Research Institute combined the data from surface water and groundwater to create a new numerical model that can analyze and predict water availability in the region.

This picture shows how the numerical model was assembled.

So, on the left, you see a sort of a dendritic pattern.

It looks like a leaf of a tree.

And you see all these conduits that have been placed in the model that have preferential flow, allowing faster groundwater flow.

Then, on the right, you see the rest of the model, and that includes the rock matrix.

The rock matrix is what we call the sponge.

These conduits are what we call the pipes.

And when we couple those together, and groundwater and surface water, we have a rather intricate coupled model that takes into account both surface water and groundwater.

Now we understand a fair bit better how these two watercourses, surface water and groundwater, interact out in this area, and we have, I think, developed a good tool in order to help manage the resources as we go forward.

Mudslides can be a dangerous and deadly natural event, and are often triggered after widespread wildfires.

In California, emergency responders and the U.S. Geological Survey are researching better ways to be prepared in the event of a mudslide.

Here's a look.

December 2017, Southern California fell victim to the worst wildfire ever recorded in state history.

The Thomas Fire burned nearly 300,000 acres, scorching everything in its path, all the way from Ventura County to Santa Barbara County, which is about two hours north of downtown Los Angeles.

No sooner were Californians out of harm's way from the devastating blaze, Mother Nature dealt a different kind of wrath.

In January, heavy, intense rains caused unprecedented mudslides and debris flows in the Montecito neighborhood of Santa Barbara County because of all the scorched earth from the Thomas Fire.

21 people died in this disaster.

More than 100 homes were destroyed, over 300 damaged, and part of one of California's busiest highways, Highway 101, was shut down for nearly two weeks.

Kate Scharer is a geologist with the United States Geological Survey.

She was part of the response team which aided in the Montecito rescue effort, and also helped with damage surveillance and assessment.

Today, we met Scharer out here, at a debris basin the Sylmar community of Los Angeles County, located at the base of the San Gabriel Mountains.

In December, parts of Sylmar were also scorched from what was known as the Creek Fire.

The material that you can see on the landscape is what becomes a debris flow.

A common word that's used to describe that is actually a mudflow.

We like to use the term 'debris flow' because it includes not just mud from the soil, but also the big rocks, the trees, big chunks of the bedrock or the hillslope that can get entrained in these flows as they go downhill.

So the reason we like to say debris flow is it's a huge variety of material that comes down, not just mud.

Is that what causes the devastation?

Is it the velocity and the violence of the flow?

Or is it something else?

It's certainly the velocity of it.

Debris flows can move as fast as 30 to 40 miles an hour.

If you think of yourself driving in a car at that speed, you certainly wouldn't want to hit anybody, right?

When you envision that you could take all the material in the landscape and have it move that quickly in a slurry that has a concentration of, like, cement, for example, and it's moving that fast, it can take you out very quickly.

Scharer explains these charred hills here in Sylmar are exactly like the hillsides in Montecito after the Thomas Fire.

The inferno burned all the living and dead vegetation that had sheltered the soil.

The lands quickly eroded because there was no protective shield or barrier from the debris flow.

You can see where there used to be vegetation, before the fire.

And that vegetation, all of the roots that go in, the smaller plants that have burned up, all of those roots go in and basically lock the soil into the bedrock.

Once you have this burned, those roots that act like the staples that hold the soil into the ground are all gone, and so for two to five years after one of these fires, you can expect that, if the right kind of rainstorm comes through, material will get mobilized.

Just this thin veneer of soil and rubble will get mobilized, and can come down in a debris flow.

There is no way to quickly get away from this once the land starts crumbling down?

That's correct.

The descriptions you hear from people, that it sounds like a freight train coming at you.

So you can envision -- you have boulders out in the Montecito area.

We were measuring boulders that were two meters high.

That's taller than me.

And you're 6 feet tall.

Yes. [ Laughs ] And so those things were coming down with a velocity of 40 miles an hour.

That's, equivalently, a truck coming at you.

I have not seen a debris flow this bad within the last 20 years.

Janis Hernandez is with the California Geological Survey.

Hernandez was also part of the team out at Montecito, helping emergency responders and also documenting the path of the debris flow and mudslide.

Debris flows are characterized as sediment, rock, wooded debris, materials, air, and water that just get entrained and mobilized in a rapid deposit.

They come barreling down the canyons at a rapid pace, and as this material works its way down the slopes, it's picking up stuff.

We call it entraining.

But it's picking up stuff from the sides, from the front, and it's just making the mass even greater.

If, at the bottom of the canyon, we have a debris basin down there, it's supposed to catch this heavy material and allow the lighter material, the water, to flow out of it.

But in the case after a fire, there was just too much material to come down, and the basins filled up, and they over-topped, and all that material was spilling out into the neighborhoods uncontrollably.

If you happen to be home, you most likely will become part of that deposit.

Enough material came out of the canyons to fill, perhaps, 300 football fields.

Now the California Geological Survey is educating the public.

CGS has compiled a safety-and-preparedness checklist for all California residents, and any other U.S.

residents who live in parts of the country where they could be victims of wildfires that could lead to mudslides or debris flows in the future.

First, CGS says it is critical that residents heed all evacuation warnings from local law enforcement and Weather Service officials.

Secondly, CGS tells residents to expect debris flows for two to five years after a wildfire.

It takes intense rain, typically about 1/2 inch per hour to a recently burned slope, to trigger a debris flow or mudslide.

Thirdly, monitor all National Weather Service or local weather forecasts for flash-flood watches or flash-flood warnings.

And fourthly, if you must shelter in place, choose your location in advance and stay there, and find the highest point of shelter, such as a second story or a rooftop.

To help with these life-saving efforts, geologists are combining science and technology to map the post-fire danger zones for potential mudslides and debris flows.

It's a collaborative effort with USGS and CGS, and other technical specialists such as hydrologists, engineers, the U.S. Forest Service, and the Weather Service.

Together they are helping create specialized landslide maps.

Scientists track, and then map, things like soil texture, burn severity, and topographic information.

Geologists are also using aerial imagery and satellite data, and a technology called lidar.

Lidar is another mapping technique using laser beams flowing from an airplane to collect information.

Lidar can see through things like trees, brush, and other vegetation, and with digital processing get detailed imagery of everything on the ground, like homes, buildings, creeks, rivers, drainage systems, and it can identify any type of terrain, be it rough, hilly, or mountainous, helping geologists study landforms as if they're under a magnifying glass.

Is there any way that this can be prevented, or is Mother Nature just gonna do what Mother Nature does?

Mother Nature is gonna do what Mother Nature does.

When the rain comes down, no vegetation, loose soils, it's just a recipe for disaster.

You basically get buried by the debris.

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... ♪♪ ♪♪ ♪♪ ♪♪ ♪♪