Finally, the Mind-Twitter Intersection

Last year, Ben McGrath wrote a great article for the New Yorker about the new frontier in prosthetics, which involves using the brain to transmit signals to robotic appendages. I was reminded of that article by the Silent Barrage installation at Exit Art over the weekend, and again by this bit of news.

Researchers at the University of Wisconsin have successfully used the brain-computer interface to send tweets. Their research has much loftier goals, but the Twitter project has garnered a ton of media attention.

An Evening in Rat Brains

Lately I’ve been into exploring the science-art intersection/interaction/interface. This is something I’ve been interested in since I began, in college, to notice congruence between my studies in geomorphology and literature. As my understanding of natural processes deepened, so did my thinking on literary structure and themes—I found I could use science as a context for thinking about literature, and vice versa.

I hadn’t given much thought to the visual art/science intersection before a few of months ago, when I attended a “Wonder Cabinet” at NYU. There, I spoke with a couple of artists who have created a new kind of perspective drawing. As we talked about their process of discovery and creation, I was struck by how much their inspiration was rooted in their observation of their experience of the world. In addition to beginning work on a written piece about these artists, I have been thinking a lot about the ways in which science and visual art influence each other.

This past Friday, I went to Exit Art’s Corpus Extremus exhibition. The exhibition consisted of work by a bunch of artists who are “using bio- and media- technologies to investigate questions of life and death.” Inside the gallery, familiar pieces of the biological world were being presented at unfamiliar, grotesque scales—there were enlarged photographs of diseased living tissue in thin section, and films projected on large screens depicting surgery on unidentifiable body parts. One installation featured a group of plants in a sterile, symmetrical setting. There were taxidermied rabbits under red light, and digital images of transgenic (genetically altered) insects made to fluoresce. Together, these pieces seemed to pose some question about the boundary (or lack of boundary) between the living and non-living worlds. I don’t know what the question was, exactly, but its mere suggestion made me uneasy.

In the middle of the gallery there was an installation of tall, white poles with robotic parts attached. The parts were moving up and down at seemingly random intervals and tracing black circles around the poles. I walked around in between the poles and let the weirdness of the situation build. Some of the poles were heavily marked by activity; others were entirely still. There was something unsettling about the unpredictability of their movement, their silence punctuated by a sudden mechanical hum.

When I found the placard containing the curator’s notes, I learned that the robotic arms on the 36 poles were responding to electronic stimulus from a petri dish in Atlanta, Georgia which contained a network of rat neurons; the base of the dish was covered in electrodes that could both send and receive information. Above my head was a camera which was recording my movement and sending electrical impulses through the internet, through the electrodes, to the neural network in Atlanta.



In some bizarre way, the rat neurons and I were part of a closed neural circuit, like the knee-jerk reflex or the loops our brains access when we perform simple, rote tasks. Furthermore, I was witnessing the ability of neurons to control kinetic, robotic movement. This was more than just the boundary between living and non-living worlds—it was an example of the way science can manipulate the interaction between them. While the interaction here was virtually uncontrolled and artistic in nature, the implications for controlled interaction were quite real to me as I stood there, in what had come to feel like a virtual space in which I was both wandering around within, and influencing a network of rat neurons.

I’m pretty sure the point of the installation (called Silent Barrage) was to get us thinking about harnessing neural networks to control robotics, and I think that’s pretty cool. But on the train home, the thing I couldn’t stop thinking about was the exchange between my own movements—recorded by the camera—and the rat neurons. There was something intimate about wandering around inside of living neurons’ electrical output, and knowing those neurons were responding to stimulus created by me (I may not have taken all of this so personally, but the exhibit was closing when I was there, and I was alone. I even got locked in the gallery for a minute, before someone came out of the back office to direct me out the side door). When do we get to enjoy such immediate, unfiltered interaction with a foreign set of brains? Certainly not amid the body language, perfumes, and fabrics on a Friday night on the L train.

***********
Pictures: http://www.exitart.org/site/pub/exhibition_programs/corpus_extremus/index.html

Silent Barrage is an installation by artists Guy Ben-Ary and Philip Gamblen in collaboration with the Dr. Steve Potter Lab in Atlanta, Georgia. It made its world premiere at Exit Art.

Part 2: Why is there Poop in My Margarita? my subterranean mexican blues.

My vicarious experience with Montezuma’s Revenge over the Christmas holiday raised some questions. Where, I wondered, does Mexico get its freshwater supply? And how does fecal matter make its way into this water? And what does Mexico do to filter or process its water to make it fit for human consumption?

The answer to the first question lies in the area’s geology. The Yucatan peninsula is made out of a thick layer (hundreds of meters) of limestone. Limestone is fairly ubiquitous in tropical environments because it forms in warm shallow seas from the compacted shells of sea creatures. Later, during a period of uplift, the bottom of the sea is pushed up and becomes the ground beneath our feet, or bedrock. When limestone gets broken down into sand during the process of weathering, the result are those white sandy beaches that we are used to associating with warm island vacation spots. (The characteristic turquoise blue of the water is also due to the limestone sand).

In addition to gorgeous beaches, you’re also likely to find caves wherever you find limestone. This is because the rock is composed mostly of the mineral calcium carbonate, which dissolves easily in acidic water. Thanks to the combination of high rainfall and high atmospheric carbon dioxide, much of the Yucatan’s limestone bedrock has dissolved, resulting in an extensive network of underground caves, cracks, and fissures, and a landscape dominated by classic karst topography*.

Rainwater infiltrates quickly through the highly permeable limestone until it reaches the water table—the level below which all of the empty spaces within the rock are filled with water (a large body of rock with water in all of its empty space is referred to as an aquifer). The entire population of the Yucatan peninsula gets its fresh water from natural springs or wells that tap this supply of groundwater.

In much of the Yucatan peninsula—and especially near the ocean—the water table happens to be fairly close to the ground surface. On the one hand, this makes it easy to dig a well. On the other hand, the high water table means that pollutants from the surface seep quickly and easily into the groundwater supply—these pollutants include toxic industrial, medical, human, and agricultural waste. In addition to the pollutants’ “natural” flow into the aquifers, many communities on the Yucatan actively pump liquid waste underground as a method of disposal. Solid wastes are frequently burned and then added to unlined landfills, where contaminants are leached by rainwater and carried underground.

Furthermore, because the network of cracks and caves is so extensive throughout the Yucatan, once underground pollutants can spread far from their source, contaminating vast sections of the groundwater supply.

Considering these facts, it isn’t surprising that there’s poop in the water.

In the more industrial parts of the Yucatan, such as Merida—the peninsula’s largest city—there are chemicals whose toxicity far exceed that of a few pesky strains of e. coli. One recent study of the groundwater in Merida found high levels of cadmium, arsenic, lead, iron, and chromium, none of which are beneficial to human health.

The Riviera Maya—the area south of Cancun including Playa del Carmen, Tulum, and a string of resorts—has undergone rapid development over the past ten years, bringing both huge numbers of tourists and a large industry-support population to the area. It seems wildly irresponsible to engage in rapid development of an area such as this based on its natural beauty without taking into account the environmental and—ultimately—economic impact of that development. I believe this is a matter of putting the cart before the horse, of leaping before we look, and I believe we should know better than that in this twenty-first century of ours.

We find ourselves always moving forward into an uncertain future. Often, the nature of progress requires us to rush forward in some new direction before we have the capacity to understand the consequences of our actions. The problem, as I see it, arises when we do have the capability to explore the impact of some human venture or activity, but we choose not to. Certainly, this is the case with the state of freshwater in the Yucatan peninsula, as well as many other places in the developing and developed world.

It is well within the means of science to explore the current hydrogeological state of the Yucatan peninsula. Our findings could tell us how much water is there, and to what extent it is contaminated. More importantly, we could apply this knowledge to the sustainable development of the area. How much will it cost? Can we afford not to do it?


*A karst landscape is made out of limestone and has a characteristic dry, lumpy look to it. The lack of moisture is due not to a lack of rainfall, but to the high permeability of limestone rock—when it rains, the water infiltrates quickly downward until it reaches the water table. Underground cave networks give way and fall in on themselves, giving rise to an uneven, “lumpy” ground surface. Check out Ireland’s burren for some good-looking karst landscape.

Pictures:

Limestone Beach

Aquifer

Riviera Maya

References:

Sustainable Management of Groundwater in Mexico:
Hydrogeology of a contaminated sole-source karst aquifer,
Mérida, Yucatán, Mexico

La Navidad Mexicana, Part 1. Or, When You're Sliding Into First...

Every Christmas holiday, the members of my family uproot from their various corners of the continental U.S. and converge on an area of the Greater Northern Detroit suburbs known as Lake Orion, where our parents have lived for the past ten years. Michigan is, in general, a flat state, and Lake Orion is characterized by a distinctly two-dimensional element—an element amplified by the single, white, depthless cloud that covers the sky like a non-retractable dome for the majority of the wintertime. The only notable topography in the area is a giant landfill by the highway, across from a sign that reads “Lake Orion: Where Living is a Vacation.”

And then there’s the weather. In Michigan, in late December, there are always variables—it may or may not be snowing, it may or may not be windy—but it is always cold. Really, really cold.

Regardless of the fact that we always have an excellent time in Michigan over Christmas, the family decided this year to try for a spot where living might actually feel like a vacation. And so, instead of blustery Michigan, we met up in Akumal, Mexico for a week of sunshine, relaxation, and fun—and a little diarrhea.

Everyone in the family is pretty private about these kinds of things, so I don’t really know exactly who got it and exactly how bad it was, but I know it made, at least, a brief pass through the villa.

Which made me wonder: Why are people always getting sick when they go to Mexico? Why aren’t we supposed to drink the water? What’s in the water there that makes so many visitors to the area sick? And why aren’t the native Mexicans sick? And what is diarrhea, anyway?

In Mexico, Traveler’s Diarrhea goes by the less formal name “Montezuma’s Revenge.” The name comes from the Aztec king Moctezuma whose empire fell to the Spanish in the mid-16th century (historical details are foggy, but what’s clear is that Moctezuma welcomed the Spanish explorer Hernan Cortes into his capital city of Tenochtitlan and ultimately got totally screwed by him. Sound like a familiar story?). The idea is that old Moctezuma is taking revenge on subsequent interlopers by afflicting them with vigorous bouts of nausea, cramping, vomiting, and diarrhea.

There’s also a more scientific explanation.

Traveler’s Diarrhea affects about 40% of people who visit Mexico, and is prevalent in many other underdeveloped nations around the world. While there are several bugs (parasites, bacteria, and viruses) responsible for TD, the most common culprit is a strain of e. coli referred to as enterotoxogenic e. coli, or ETEC. While it shares a proclivity for causing diarrhea with its notorious relative O157:H7, ETEC is not a deadly strain of e. coli. The good news is that most strains of e. coli are completely harmless (many take up permanent residence in our colons); the bad news is that where there is e. coli, there is poop. Which means that-- even if you don’t like to think about it-- there’s a little bit of fecal matter in the water in Mexico. (We’ll get into why that is later).

In order to understand how ETEC causes diarrhea, let’s make like an e. coli-tinged ice cube and take a hurried trip through the human GI tract:

Food begins to break down in our mouths, with the physical work of chewing and the chemical work of enzyme-laden saliva. The saliva also makes the food wet and mushy, so that it slides with relative ease* down the esophagus and into the stomach, where it hangs out for several hours. Here, gastric acid breaks the food down into a gooey, milky substance called chyme. This acidic environment also serves to kill off a number of potentially harmful bacteria.

From the stomach, the chyme makes its way into the small intestine by way of the pyloric sphincter. The small intestine is a hotbed of digestive activity where food gets broken down by a rich cocktail of bile, pancreatic juice, and digestive enzymes. The folded walls of the small intestine are covered in millions of little projections (think of a trimmed Koosh ball) that increase the surface area of the organ and allow for increased absorption of nutrients (converted glucose, fats, and amino acids). Excess liquids are also absorbed through the walls of the small intestine.

After the small intestine, food makes its last stop at the large intestine, or colon. Thanks to trillions of bacteria, this is where poop really becomes poop. The bacteria creates gas, turns the waste brown, and makes it smell like—well, shit. The colon is also theoretically where fecal matter becomes solid, due to absorption of liquid through the walls of the large intestine…

But here we need to take a step back and remember that we’re talking about diarrhea rather than semi-solid, healthy, normal feces. If the enterotoxogenic e. coli in your margarita’s ice cubes survives the gastric juices of the stomach and makes it to the large intestines, it produces a toxin that prevents the absorption of liquids and instead stimulates the opposite process. Instead of sucking moisture out of your poop, the walls of your large intestines let water in.

You know the rest of the story.

*The motion of food through the entire digestive system is aided by the action of peristalsis—the contraction and relaxation of muscles in the organ’s walls. Think of squeezing a tube of toothpaste or, perhaps more accurately, squeezing raw sausage out of it’s intestinal casing. If you’ve ever felt the urge to go to the bathroom right when you start eating, it’s because this action in the esophagus triggers a wave of peristalsis throughout the whole GI tract—all the way to the colon.

Pictures:
Digestive System
Michigan Winter
Akumal
E. Coli
Chyme

References:
The CDC
The Way We Work, David Macaulay
Textbook of Bacteriology

Q & A/Mulligan: Solar Panels

In response to my post the other day about photovoltaic cells, I received a number of responses indicating I had done an inadequate job explaining the technology. One dear friend wrote:

okay, I believe you because I trust you, but I don't totally comprehend the concept of how PV cells generate energy. It seems like scientists are trying to fool me into believing some gobbledygook they made up.

So here goes a more complete-- and hopefully better-- explanation:

The most basic idea with a solar cell is that it works by using energy from the sun, in the form of photons, to create electricity. In order to do this, engineers start off by putting two layers of "doped" silicon in contact with each other-- one of these layers is positively-charged; the other is negatively-charged.

The positively-charged layer (p-layer) has a lot of "holes"-- places where electrons could be if there were electrons available. The n-layer, on the other hand, has a lot of electrons that are extra-- you can think of them like a bunch of understudies on an acting set (they have a role, but they're really just waiting around to jump into a more stable, more important role).

When the two layers come together, the extra electrons on the n-side, close to the barrier, rush to fill the "holes" on the p-side. On the p-side, the holes migrate over to the n-side. This happens really fast, until equilibrium is reached, right at the boundary between the two sides (called the p-n junction):



Because the n-layer now has this positive charge right by the barrier, it takes too much energy for more electrons to move from the n-side to the p-side. However, electrons can move easily from the p-side to the n-side.

Of course, once the equilibrium is reached when the two layers are put together, electrons aren't going to keep moving around on their own-- they need energy to push them. Here's where photons come into play: photons are a form of energy, and when they strike the layers of silicon, they transfer that energy to electrons and dislodge them from their place. Electrons on the p-side cross the barrier to the n-side, but the electrons on the n-side can't cross to the p-side, so they get knocked around the n-side, looking for somewhere to go.



In a solar cell, some of those electrons end up in metal conducting strips (remember those thin silver lines on the PV cell on your calculator?) in the solar panel, which move the electrons out of the cell and into a wire-- generating electricity!



The solar panel is a closed-loop system, meaning that the electrons that are lost through the metal conducting strips and into the wire travel aren't lost forever-- after doing their job generating electricity, they travel back through the wire and are picked up by a conductive metal backing on the back of the solar panel, where they transfer back to the p-layer.

The whole solar panel has a number of parts-- we've mentioned the two layers of silicon, the metal conducting bands, and the metal backing. The top of the panel is also covered in an anti-reflective coating so that the panel can absorb as much light as possible, and the whole thing is covered in a layer of protective glass:



If you're with me to this point, you can see why solar panels are fairly inefficient producers of energy, even though the sun is so powerful. Only certain levels of energy from the sun knock the electrons in the silicon out of place; also, of the electrons that do start to fly around, only a few of them make it into the metal conducting strips.

Does this Ring a Bell?

My friend Will e-mailed me this today!

GBW: IKEA cometh to Brooklyn

I have a hate/love/(hate again) relationship with IKEA. I hate the light-birch color of their furniture, because it reminds me of the flesh in a freshly-axed tree, which makes me feel guilty. I love IKEA because it has supplied me with almost all of my furniture (mostly via craigslist). And I hate IKEA again because the entire store is set up to make customers disoriented and lost, so that they come back to the same sections over and over until they decide to buy the merchandise they didn’t think they wanted, like trick answers on a multiple-choice test.

That said, many of our city-dwelling, carless lives have been eased significantly by the opening of an IKEA in Brooklyn this past June. And although it’s located in transportationally-challenged Red Hook, IKEA makes itself accessible to visitors with free shuttles from the F and G trains, a free water taxi to Manhattan, and direct service on two Brooklyn bus lines. In addition, you can rent a UHAUL right out of the parking garage to drive large purchases home.

The Brooklyn IKEA is also pleading its case as a social/environmentally responsible superstore by applying for a silver LEED certificate. The most significant green feature of IKEA is the huge photovoltaic array on its roof, which provides the building with somewhere between 5 and 10 percent of its energy needs.

Put simply, photovoltaic cells work by converting light (photo) energy into electric (voltaic) energy. Although it seems like people are talking about “solar energy” as a relatively new idea, the roots of photovoltaic (PV) technology goes back about 170 years to a French physicist named Alexandre Edmond Becquerel. Becquerel was the first to observe (or at least get credit for observing) that electricity could be created by shining light on to certain chemical solutions. One century and several brilliant minds later, Bell Labs introduced the first high-powered PV silicon cell, and the NY Times predicted that solar cells would lead to a source of “limitless energy” (If I had a nickel for every time...).

PV technology is not only pretty old, but it’s also fairly ubiquitous. Unless you went to school before the 1980’s, your first memory of PV cells probably dates back to your first calculator. And unless you were an exceptionally engaged student, you probably spent some time in math class covering the light sensor with your finger and watching the numbers fade gradually from the display screen, only to reappear when your finger was removed. Voila-- your first tactile experience with semiconductors!

A photovoltaic cell works by using a semiconductor—a material that has some qualities of an insulator and some qualities of a conductor. The most common semiconductor is silicon. In it’s pure state, silicon is stable, meaning that it has neither too many nor too few electrons. However, another trace element can be added to silicon to disturb this balance. This process is called doping, and people use it to create sheets of negatively-charged (n) and positively-charged (p) silicon.

To create a PV cell, the two sheets of semiconductor-- one with extra electrons (n-silicon) and one missing electrons (p-silicon)-- are placed together. When the sun's energy, in the form of photons, strikes the negatively-charged layer, electrons are knocked loose and move toward the p-silicon. This movement of electons creates an electric field, generating electricity.