Search Results for: lter

7.24.20

Limit by limit: Nutrients control algal growth in Arctic streams

The Arctic Stream Team. Frances, Breck, Abby, Alex, Jay, and Arial at Toolik Field Station in 2019. 

The activities are as follows:

You rely on the nutrients from the foods you eat to grow and thrive. Other organisms, like microbes, do as well! Aquatic algae, a type of microbe that live in the water, need to take in nutrients from their surroundings for growth. Two important nutrients for algal growth are nitrogen (N) and phosphorous (P).

Sometimes the environment does not have all the nutrients that aquatic algae need to grow. When one nutrient is less available compared to others, algae can become nutrient limited. Research on nutrient limitation started with Justus Liebig, a 19th century scientist who proposed the “law of the minimum.” The law states that the nutrient available in the lowest amount relative to demand will limit overall growth and production. This means that growth is not controlled by all the nutrients, but by the scarcest one (the “limiting factor”). When more than one nutrient limits growth, algae are considered co-limited. This just means that a combination of two nutrients are needed for algae to grow. Knowing what nutrients are limiting growth helps scientists understand how an ecosystem is working.  

From other research we know that many ecosystems, including those in the Alaskan Arctic, are phosphorus-limited. Scientists figured this out because they found if they added phosphorus, then algae growth increased. However, climate change could change this. As the Arctic warms, ecosystems on land might start to release nutrients in higher amounts or new proportions into the water. These extra nutrients will likely cause increases in algae growth in streams and ponds, which in turn could change food webs and nutrient cycling. It is therefore important to understand which nutrients are currently limiting algae growth before climate change changes things even more. This starts with tests to see how Arctic algae grow in response to changes in N, P, and N and P in the water.  

A team of scientists got to work on this question! Arial, Jay, Frances, Alex, Breck, and Abby are all interested in understanding how climate change may alter nutrient limitations in Arctic streams. Each team member has a unique role in the larger research project. For example, undergraduate researcher Abby spent her 2019 summer at Toolik Field Station in Northern Alaska as part of a research opportunity. She explored nutrient limitation in one particular lake, called Lake I8. 

Abby used small cups that placed into the streams that fed into Lake I8. These cups were filled with agar gel, a material used in labs to grow microbes. Each cup contained different nutrient treatments. Abby used four different treatments in her cups: (1) a control (agar only), (2) agar + nitrogen, (3) agar + phosphorus, and (4) agar + nitrogen + phosphorus. On the top of each cup, she placed a glass disk to provide a surface for the algae to grow.

A. Cups before going into the stream. B. Abby putting out her cup treatments into an Arctic stream. C. Cups incubating under water in an Arctic stream. D. Analyzing Chlorophyll a extracted from the cups. 

Abby put 5 replicate cups for each treatment at both the Inlet and Outlet streams on the I8 Lake. She left them underwater for 4 weeks. She brought the cups back to the lab to measure the algae that grew on each glass disk. Abby measured how much algae grew on each disk by measuring the amount of Chlorophyll a, the green pigment that helps plants photosynthesize. The more pigment, the more the algae is growing. Abby compared the data from the control to each of the other treatments. When there is more growth in a treatment compared to the control, that means a particular nutrient was limiting at that location. Abby expected that the streams would be limited by the amount of phosphorus, but not the amount of nitrogen. She predicted algae would grow more when they are given additional phosphorus compared to the control treatment.

Featured scientists: Abigail Rec from Gettysburg College; Frances Iannucci, Alex Medvedeff, and Breck Bowden from University of Vermont; Arial Shogren and Jay Zarnetske from Michigan State University

Flesch–Kincaid Reading Grade Level = 8.6

4.10.20

Working to reduce the plastics problem

stretching the raw, preformed polymers
Nick (right) and one of his students (left) stretching the raw, preformed polymers.

The activities are as follows:

Plastics are materials that can be shaped easily and are used for many functions. This has made them extremely popular across the world. Thousands of products are made using plastic, including parts of cell phones, food wrappers from your lunch, and even the stitches you may need after an injury. In fact, if you look around right now, you can probably spot at least ten items made of plastic!

Once a plastic is made, it tends to stick around. Synthetic plastics, made by humans from petroleum, cannot be broken down by nature’s decomposers – bacteria and fungi. This means they impact the environment for many, many years. Some types can take thousands of years or longer to break down! 

Nick is a chemist concerned with the negative impacts caused by plastics. He knows that in order to reduce the amount of synthetic plastics in the environment, we need an alternative. And, this alternative needs to be just as good as the synthetic plastic it is replacing. Nick and his undergraduate students at Northland College are testing new ways to make plastics that are biodegradable, meaning they can be decomposed naturally and won’t last as long in the environment. His research focuses on stretchy plastics, called elastomers.Elastomers are what make up rubber bands, tires, hoses, non-latex gloves, and many more items we use every day. 

To try to solve the problem of making a biodegradable elastomer that has all the qualities of a synthetic one, Nick and his students got to work. First, they had to consider the chemical structure of plastics. Plastics are made of polymers. “Poly” means “many” and “mer” means “parts”. This means that plastics are made of long chain molecules with many repeating parts. These repeating parts are called monomers. Different monomers can be used to make different types of plastic.

Nick chose to test two biodegradable monomers – diglycerol and meso-erythritol. Diglycerol is cheap and easy to buy. However, it might be too soft when used on its own. Meso-erythritol is more expensive, but more rigid. They wanted to use diglycerol and meso-erythritol because the chemical structures have the potential to create something that is not too rigid and not too flexible.

Nick and his students designed an experiment in which they tested elastomers made from each of the monomers (diglycerol and meso-erythritol) alone, as well as elastomers made using both types of monomers. They made elastomers with the following percentage ratios of diglycerol over meso-erythritol: 100/0, 75/25, 50/50, 25/75, 0/100. The team was hoping to find the “sweet spot” between a product that is too stiff, and one that is not stiff enough to be useful in elastic materials. Once they finished making their elastomers, they prepared the stretch tests. 

To start a stretch test, the team had to stamp out a piece of material from each elastomer, creating samples with the same size, shape, and thickness. They also cut pieces from rubber bands made of synthetic plastics to compare as a control. Next, they tested the elastomers using a machine that measures how much force is applied (stress) as a material is stretched (strain), both important measures of elasticity. The stress, or force per unit of area, is measured in megapascals (MPa) while the strain, or amount of stretch, is measured as a percent of the original length. 

Featured scientist: Nick Robertson from Northland College. Written by: Theresa Paulsen from Ashland High School, Wisconsin

Flesch–Kincaid Reading Grade Level = 9.6

For additional information on the plastic problem, and Nick’s research, check out the following resources:

1.17.20

Teacher Feature – Karen Murphy

Our first Teacher Feature is by Karen Murphy, who recently used one of our new Data Nuggets by the Harvard Forest LTER with her ecology students. Karen a high school science and special education teacher at Summit Academy, a public day school in Amherst, Massachusetts. 

I was able to use A window into a tree’s world Data Nugget with my ecology class as part of a unit on the carbon cycle. I found that students were interested in the relationship between tree rings and temperature/climate. They appreciated the idea of being able to determine past climate and tree age using tree rings. I asked one student for specific feedback and she said that the assignment was “interactive, informative, and fun.”

This Data Nugget provided students with access to a current, real example of the scientific method in action. For example, the class was able to practice identifying the independent and dependent variables, graph and analyze data, and to build on this knowledge to creatively form their own questions for further research. 

I greatly appreciate the Teacher Guide and PowerPoint that were found on the web page. There is a lot of valuable information to share with the class, including instructional material on the science of climate change and sources of evidence. I now hope to incorporate more Data Nuggets into future classes.

12.11.19

A window into a tree’s world

Neil taking a tree core from a pine tree.

The activities are as follows:

According to National Aeronautics and Space Administration (NASA) and the National Oceanic Atmospheric Administration (NOAA), the years 2015-2018 were the warmest recorded on Earth in modern times! And it is only expected to get warmer. Temperatures in the Northeastern U.S. are projected to increase 3.6°F by 2035. Every year the weather is a bit different, and some years there are more extremes with very hot or cold temperatures. Climate gives us a long-term perspective and is the average weather, including temperature and precipitation, over at least 30 years. 

Over thousands of years, tree species living in each part of the world have adapted to their local climate. Trees play an important role in climate change by helping cool the planet – through photosynthesis, they absorb carbon dioxide from the atmosphere and evaporate water into the air. 

Scientists are very interested in learning how trees respond to rapidly warming temperatures. Luckily, trees offer us a window into their lives through their growth rings. Growth rings are found within the trunk, beneath the bark. Each year of growth has two parts that can be seen: a light ring of large cells with thin walls, which grows in the spring; and a dark layer of smaller cells with thick walls that forms later in the summer and fall. Ring thickness is used to study how much the tree has grown over the years. Dendrochronology is the use of these rings to study trees and their environments.

Different tree species have different ranges of temperatures and rainfall in which they grow best. When there are big changes in the environment, tree growth slows down or speeds up in response. Scientists can use these clues in tree’s rings to decipher what climate was like in the past. There is slight variation in how each individual tree responds to temperature and rainfall. Because of this, scientists need to measure growth rings of multiple individuals to observe year-to-year changes in past climate.

Jessie taking a tree core in the winter.

Jessie and Neil are two scientists who use tree rings for climate research. Jessie entered the field of science because she was passionate about climate change. As a research assistant, Neil saw that warming temperatures in Mongolia accelerated growth in very old Siberian pine trees. When he later studied to become a scientist, he wanted to know if trees in the eastern U.S. responded to changes in climate in the same way as the old pine trees in Mongolia. As a result, there were two purposes for Jessie’s and Neil’s work. They wanted to determine if there was a species that could be used to figure out what the climate looked like in the past, and understand how it has changed over time.

Jessie and Neil decided to focus on one particular species of tree – the Atlantic white cedar. Atlantic white cedar grow in swamps and wetlands along the Atlantic and Gulf coasts from southern Maine to northern Florida. Atlantic white cedar trees are useful in dendrochronology studies because they can live for up to 500 years and are naturally resistant to decay, so their well-preserved rings provide a long historical record. Past studies of this species led them to predict that in years when the temperature is warmer, Atlantic white cedar rings will be wider. If this pattern holds, the thickness of Atlantic white cedar rings can be used to look backwards into the past climate of the area. 

To test this prediction, Jessie and Neil needed to look at tree rings from many Atlantic white cedar trees. Jessie used an increment borer, a specialized tool that drills into the center of the tree. This drill removes a wood core with a diameter about equal to that of a straw. She sampled 112 different trees from 8 sites, and counted the rings to find the age of each tree. She then crossdated the wood core samples. Crossdating is the process of comparing the ring patterns from many trees in the same area to see if they tell the same story. Jessie used a microscope linked to a computer to measure the thickness of both the early and late growth to the nearest micrometer (1 micrometer = 0.001 millimeter) for all rings in all 112 trees. From those data she then calculated the average growth of Atlantic white cedar for each year to create an Atlantic white cedargrowth index for the Northeastern U.S. She combined her tree ring data with temperature data from the past 100 years.

Featured scientists: Jessie K Pearl, University of Arizona and Neil Pederson, Harvard University. Written by Elicia Andrews.

Flesch–Kincaid Reading Grade Level = 9.9

Suggestions for inquiry surrounding this Data Nugget:

These videos, demonstrating the science of dendrochronology, could be a great way to spark class discussions:

11.4.19

Streams as sensors: Arctic watersheds as indicators of change

Jay taking field notes next to a rocky Tundra stream.

The activities are as follows:

The Arctic, Earth’s region above 66° 33’N latitude, is home to a unique biome, known as tundra. A defining trait of tundra ecosystems is the frozen land. Permafrost is the underground layer of organic matter, soil, rock, and ice that has been frozen for at least 2 full years. Plant material decays slowly in the Arctic because of the cold temperatures. Building up over thousands of years, the plants become frozen into the permafrost. Permafrost represents a very large “sink” of dead plant material, nutrients, and soil that is locked away in a deep freeze. 

Though the Alaskan Arctic may seem far away from where you live, tundra permafrost is important for the entire globe. During the past few thousand years, Earth’s climate has naturally changed a little over time, but because humans are adding greenhouse gases to the atmosphere, the average global temperature may increase by as much as 2 to 4oC over the next century. As a result of global climate change, permafrost has become less stable. By causing warmer and wetter conditions in the Arctic, thawing permafrost soils release ancient material that was previously frozen and locked away. Two important materials are dissolved nitrogen (N), which is a nutrient critical for plant growth, and carbon (C), which is stored in plant matter during photosynthesis. These released materials can be used again by plants, but some is carried away as melted water flows from the land into rivers and streams. You can imagine N and C in permafrost like a bank account where the landscape is the savings account. The land slowly deposits or withdraws N and C from the savings account, while the water receives any excess N and C that the land does not save.

Arial downloads data from a water quality monitoring station at the Kuparuk River. The station is connected a sensor that stays in the river and takes a reading for both carbon and nitrogen concentrations every 15 minutes.

The water that melts as permafrost thaws flows into a stream, ultimately ending up in an ocean. Watersheds are the network of streams and rivers that flow to a single point as they empty out into the ocean. The water at the end of the watershed therefore reflects all the changes that happened across a large area. Scientists use Arctic watersheds as large “sensors” to understand how and when landscapes may be releasing material from thawing permafrost. 

Because the Alaskan Arctic is a vast, sparsely populated area, scientists often rely on established field stations to conduct experiments, collect observational data, and develop new understanding of Arctic ecosystems. One of these field sites is Toolik Field Station. Scientists working at Toolik have been monitoring terrestrial and aquatic Arctic ecosystems since the late 1970s. 

Arial and Jay are aquatic scientists who work at Toolik. They are interested in how Arctic watersheds respond to climate change. Together, Arial and Jay act like ecosystem accountants: they use the chemistry within the water to monitor changes in ecosystem budgets of C and N. Arial and Jay used both historic data and water quality sensors deployed in 2017 and 2018 to monitor the N and C budget in the Kuparuk River. They use this data to calculate how much N and C the river is spending. They measure this as the total export in units of mass per year. This mass per year is determined by multiplying concentration (mass/volume) by flow (volume/day) and adding these values across the whole season (mass/year). These budgets at the watershed outlet help reveal signals of how this tundra landscape may be changing. In this way, they can assess if the landscape savings account for N and C is being depleted due to climate change. 

Featured scientists: Arial Shogren and Jay Zarnetske from Michigan State University

Flesch–Kincaid Reading Grade Level = 10.8

10.29.19

The carbon stored in mangrove soils

Tall mangroves growing close to the coast.

The activities are as follows:

In the tropics and subtropics, mangroves dominate the coast. There are many different species of mangroves, but they are all share a unique characteristic compared to other trees – they can tolerate having their roots submerged in salt water.

Mangroves are globally important for many reasons. They form dense forested wetlands that protect the coast from erosion and provide critical habitat for many animals. Mangrove forests also help in the fight against climate change. Carbon dioxide is a greenhouse gas that is a main driver of climate change. During photosynthesis, carbon dioxide is absorbed from the atmosphere by the plants in a mangrove forest. When plants die in mangrove forests, decomposition is very slow. The soils are saturated with saltwater and have very little oxygen, which decomposers need to break down plants. Because of this, carbon is stored in the soils for a long time, keeping it out of the atmosphere.

Sean is a scientist studying coastal mangroves in the Florida Everglades. Doing research in the Everglades was a dream opportunity for Sean. He had long been fascinated by the unique plant and animal life in the largest subtropical wetland ecosystem in North America. Mangroves are especially exciting to Sean because they combine marine biology and trees, two of his favorite things! Sean had previously studied freshwater forested wetlands in Virginia, but had always wanted to spend time studying the salty mangrove forests that exist in the Everglades. 

Sean Charles taking soil samples amongst inland short mangroves.

Sean arrived in the Everglades with the goal to learn more about the factors important for mangrove forests’ ability to hold carbon in their soils. Upon his arrival, he noticed a very interesting pattern – the trees were much taller along the coast compared to inland. This is because mangroves that grow close to the coast have access to important nutrients found in ocean waters, like phosphorus. These nutrients allow the trees to grow large and fast. However, living closer to the coast also puts trees at a higher risk of damage from storms, and can lead to soils and dead plants being swept out to sea. 

Sean thought that the combination of these two conditions would influence how much carbon is stored in mangrove soils along the coast and inland. Larger trees are generally more productive than smaller ones, meaning they might contribute more plant material to soils. This led Sean to two possible predictions. The first was that there might be more carbon in soils along the coast because taller mangroves would add more carbon to the soil compared to shorter inland mangroves. However, Sean thought he might also find the opposite pattern because the mangroves along the coast have more disturbance from storms that could release carbon from the soils. 

To test these competing hypothesis, the team of scientists set out into the Everglades in the Biscayne National Park in Homestead, Florida. Their mission was to collect surface soils and measure mangrove tree height. To collect soils, they used soil cores, which are modified cylinders that can be hammered into the soil and then removed with the soil stuck in the tube. Tree height was measured using a clinometer, which is a tool that uses geometry to estimate tree height. They took these measurements along three transects. The first transect was along the coast where trees had an average height of 20 meters. The second transect between the coast and inland wetlands where trees were 10 meters tall, on average. The final transect was inland, with average tree height of only 1 meter tall.  With this experimental design Sean could compare transects at three distances from the coast to look for trends. 

Once Sean was back in the lab, he quantified how much carbon was in the soil samples from each transect by heating the soil in a furnace at 500 degrees Celsius. Heating soils to this temperature causes all organic matter, which has carbon, to combust. Sean measured the weight of the samples before and after the combustion. The difference in weight can be used to calculate how much organic material combusted during the process, which can be used as an estimate of the carbon that was stored in the soil. 

Featured scientist: Sean Charles from Florida International University

Flesch–Kincaid Reading Grade Level = 9.6

Additional teacher resources related to this Data Nugget:

Digital Data Nuggets on DataClassroom

We partnered with DataClassroom to create new Digital Data Nuggets! These activities allow your students to easily explore large datasets and make beautiful graphs, develop their data literacy abilities, do statistics, and more. All Digital Data Nuggets can be found here.

Click here to access Digital Data Nuggets on DataClassroom!

Although DataClassroom offers some paid features, Digital Data Nuggets will always be free. Once you are logged in to DataClassroom, look for the Data Nuggets “DN” logo in the list of datasets. The first time you visit their site you will have to create an account using your email or connecting through Gmail. Once you’re logged in, this link should bring you directly to the table of Digital Data Nuggets.

8.8.19

Digital Data Nuggets on DataClassroom!

We are so excited to announce that we have partnered with our friends at DataClassroom to create new “Digital Data Nuggets“! These activities allow your students to easily make beautiful graphs, develop their data literacy abilities, do statistics, and play with data visuals for free in the DataClassroom tool. Although DataClassroom.com offers some paid features, Digital Data Nuggets will always be available with their free version. Once you are logged in to DataClassroom, look for the Data Nuggets “DN” logo in the list of datasets.

Click here to register a free password at DataClassoom.

Click here for a quick tutorial on making graphs with DataClassroom.

DataClassroom was created by our good friend, Aaron Reedy, a former high school teacher and evolutionary biologist. He developed them as the digital data-tool that he always wished he had when he was teaching in his Chicago Public School classroom. In addition to exploring the Data Nugget datasets, DataClassroom lets students upload their own data, easily create graphs, and even conduct animated chi-square or t-tests when they are ready to move up to null hypothesis testing. Aaron is willing to demo the full DataClassroom tool for any interested teacher or school. You can directly send questions, feedback, or a request for a demo to Aaron at aaron@dataclassroom.com.

Leave a comment below to let us know what you think about Digital Data Nuggets!

1.15.19

Hold on for your life! Part II

In Part I the data showed that, after the hurricanes, anole lizards had on average smaller bodies, shorter legs, and larger toe pads. The patterns were clear and consistent across the two islands, indicating that these traits are adaptations shaped by natural selection from hurricanes. At this point, however, Colin was still not convinced because he was unable to directly observe the lizards during the hurricane.

Still shot of lizard clinging to an experimental perch in hurricane-force winds. Wind speed meter is displaying in miles per hour

The activities are as follows:

Colin was unable to stay on Pine Cay and Water Cay during the hurricanes and directly observe the lizards. To be more confident in his explanation, Colin needed to find out how lizards behave in hurricane-force winds. He thought there were two options for what they might do. First, he thought they might get down from the branch and hide in tree roots and cracks. Alternatively, they might hold onto branches and ride out the storm. If they tried to hold on in high winds, it would make sense that traits like the length of their limbs or the size of their toepads would be important for their survival. However, if they hid in roots or cracks, these traits might not be adaptations after all.

To see how the lizards behaved, Colin needed to design a safe experiment that would simulate hurricane-force winds. He bought the strongest leaf blower he could find, set it up in his hotel room on Pine Cay, and videotaped 40 lizards as they were hit with high winds. Colin first set up this experiment to observe behavior, but he ended up learning not only that, but a lot about how the traits of the lizards interacted with high winds.

To begin the experiment, Colin placed the anoles on a perch. He slowly ramped up the wind speed on the leaf blower until the lizards climbed down or they were blown, unharmed, into a safety net. He recorded videos of each trial and took pictures. 

Featured scientist: Colin Donihue from Harvard University

Written with: Bob Kuhn and Elizabeth Schultheis

Flesch–Kincaid Reading Grade Level = 8.4

Additional teacher resources related to this Data Nugget:

  • This study was published in the journal Nature in 2018. Colin would like to thank his coauthors Anthony Herrel, Anne-Claire Fabre, Anthony Geneva, Ambika Kamath, Jason Kolbe, Tom Schoener, and Jonathan Losos. You can read the paper here.
  • Colin wrote a blog post about his experience. He shares more about the lead-up to the project and how a chance occurrence changed the entire trajectory of his research.
  • Colin also put together a story map with more images and animated gifs of this research.
  • We put together a PowerPoint of images from Colin’s research that you can show in class to accompany the activity.

To engage students in this activity, show the following video in class. This video gives some information on the experiment and Colin’s research.

1.15.19

Hold on for your life! Part I

Anolis scriptus, the Turks and Caicos anole, on Pine Cay.

The activities are as follows:

On the Caribbean islands of Turks and Caicos, there lives a small brown anole lizard named Anolis scriptus. The populations on two small islands, called Pine Cay and Water Cay, have been studied by researchers from Harvard University and the Paris Natural History Museum for many years. In 2017, Colin, one of the scientists, went to these islands to set up a long-term study on the effect of rats on anoles and other lizards on the islands. Unbeknownst to him, though, a storm was brewing to the south of the islands, and it was about to change the entire trajectory of his research.

While he was collecting data, Hurricane Irma was developing into a massive category 5 hurricane. Eventually it became clear that it would travel straight over these small islands. Colin knew that this might be the last time he would see the two small populations of lizards ever again because they could get wiped out in the storm. It dawned on him that this might be a serendipitous moment. After the storm, he could evaluate whether lizards could possibly survive a severe hurricane. He was also interested in whether certain traits could increase survival. Colin and his colleagues measured the lizards and vowed to come back after the hurricane to see if they were still there. They measured both male and female lizards and recorded trait values including their body size, femur length, and the toepad area on their forelimbs and hindlimbs.

Colin was not sure whether the lizards would survive. If they did, Colin formed two alternative hypotheses about what he might see. First, he thought lizards that survived would just be a random subset of the population and simply those that got lucky and survived by chance. Alternatively, he thought that survival might not be random, and some lizards might be better suited to hanging on for their lives in high winds. There might be traits that help lizards survive hurricanes, called adaptations. He made predictions off this second hypothesis and expected that survivors would be those individuals with large adhesive pads on their fingers and toes and extra-long legs – both traits that would help them grab tight to a branch and make it through the storm. This would mean the hurricanes could be agents of natural selection.

Not only did Hurricane Irma ravage the islands that year, but weeks later Hurricane Maria also paid a visit. Upon his return to Pine Cay and Water Cay after the hurricanes, Colin was shocked to see there were still anoles on the islands! He took the measurements a second time. He then compared his two datasets from before and after the hurricanes to see if the average trait values changed.

Featured scientist: Colin Donihue from Harvard University

Written with: Bob Kuhn and Elizabeth Schultheis

Flesch–Kincaid Reading Grade Level = 9.9

Additional teacher resources related to this Data Nugget:

  • This study was published in the journal Nature in 2018. Colin would like to thank his coauthors Anthony Herrel, Anne-Claire Fabre, Anthony Geneva, Ambika Kamath, Jason Kolbe, Tom Schoener, and Jonathan Losos. You can read the paper here.
  • Colin wrote a blog post about his experience. He shares more about the lead-up to the project and how a chance occurrence changed the entire trajectory of his research.
  • Colin also put together a story map with more images and animated gifs of this research.
  • We put together a PowerPoint of images from Colin’s research that you can show in class to accompany the activity.

To engage students in this activity, show the following video in class. This video gives some information on the experiment and Colin’s research. For Part I stop the video at minute 1:30.

« Previous Page
Next Page »