Deuterium: Heavy Water, Tiny Probe

My grandfather was a big fan of the old sitcom Hogan’s Heroes, and to some extent, I’ve inherited his taste in comedy.  The episode which sticks out in my mind the most, centers around a heavily guarded barrel of water.  Numerous rumors circulate about why the barrel of water is so important, including one that the water is from the Fountain of Youth, but eventually it is revealed that the barrel simply contains “heavy” water.  Prior to my days as a student of chemistry,  this begged the question: what makes the water  so “heavy”?

You may be aware that a molecule of water consists of three atoms: two hydrogen atoms and one oxygen atom.  Water becomes “heavy” when the hydrogen atoms in water are substituted with a rare isotope of hydrogen. In case you’re not familiar with isotopes, you can think of isotopes as being the same basic building blocks of a molecule, only with a tiny bit of extra mass. This brings me to our main topic of discussion: deuterium.

A hydrogen atom, represented by a white sphere, is turned into a deuterium atom, represented by a green sphere, by the addition of a neutron, represented by a lowercase letter "n".
Addition of one neutron (n) to an atom of hydrogen (H) produces deuterium (D).

Both deuterium (D) and hydrogen (H) consist of one electron and one proton, but deuterium also has a neutron, which is what provides the extra mass in heavy water.  More succinctly, it can be said that deuterium is an isotope of hydrogen.  This subtle subatomic difference is all that distinguishes heavy water (D2O) from regular water (H2O), but the unique properties of D2O permit a myriad of applications in chemistry and physics.   (more…)

Earth Day 2017: Onwards and Upwards

“Unless someone like you cares a whole awful lot,
 nothing is going to get better. It’s not.”
Dr. Seuss, The Lorax

Less than fifty years ago on April 22, 1970, the modern day environmental movement was born and the first Earth Day was celebrated. Rachel Carson, scientist and writer, is credited with raising environmental awareness with the publication of her book, Silent Spring, in 1962. That publication, the political climate of the time, and a series of human-caused environmental disasters led twenty million people to come together and rally for the protection of the environment. On April 22, 2017 it is estimated that over 200 million people worldwide will follow suit and celebrate Earth Day. (more…)

Earth Day 2017: Reclaiming Climate Science

When scientists communicate with the public about politics, they often frame the issue as “science vs. politics.”  For instance, some scientists champion speaking truth to power, while others suggest that they stay out of the political fray altogether.  Both arguments assume that science and politics are independent and mutually exclusive.  Furthermore, they presuppose that science could and should remain politically neutral.  I’d like to discuss why this framing is problematic and how we might instead understand the political role of science.  Since Earth Day is just around the corner, let’s focus on climate science in the public discourse.

This same science-vs.-politics framing has arisen in the discussion of the recent actions of the Trump administration.  Many scientists and science supporters consider the White House to have an “anti-science agenda,” especially regarding environmental science and climate change.  This agenda included a temporary suspension of all Environmental Protection Agency grants, removal of the White House’s climate change webpage, and restriction of public communications for agencies such as the National Park Service.  In response, many scientists condemned the White House’s actions as politics interfering with sound science.  Following the Women’s March on Washington, they focused their energy toward a public demonstration, now officially “the March for Science,” which is planned for Earth Day (April 22) 2017.

Science activists wearing white lab coats hold signs such as “Scientists serving the common good,” “Stand up for science,” and “Scientists speaking truth to power.” They are gathered at a rally in Boston to “Stand Up for Science.” Many of the rally participants were also attendees at the AAAS annual conference during the same afternoon.
Coinciding with the annual meeting of the American Association for the Advancement of Science (AAAS), science activists rally to “Stand Up for Science” in Boston this past February. Marches and rallies for science are becoming an increasingly common form of political activism (Credit: Sarah McQuate at


Heritability: what it means and why it’s important

A cluster of points is plotted on a coordinate plane with x values randing from 155 to 180 and y values ranging from 160 to 180. A best-fit line is plotted against them
Simulated data for 1000 families representing heritability for some trait, say height in centimeters. Each point represents the mean of the offspring plotted against the mean of the parents. In this case, heritability, or the slope of the line, is 0.60.

In a previous post, I briefly discussed something called genetic correlation and how this might be important for the evolution of a trait. Now, I hope to further clarify that concept and add to that a discussion of a very important concept in evolutionary biology—heritability—and tie it back to my initial discussion of the evolution of pesticide resistance.

Consider your siblings or the siblings of a friend and you will likely observe that inheritance of a trait is not a binary distinction.  In other words, it is not always as simple as either having or not having a trait from a parent.  Chances are, neither you nor your siblings are exactly the same height as either of your parents, or their mean (or average). This is because height–and virtually every other quantitative trait, or one that is variable along some continuum—has an associated heritability (or h2). As an aside, the notation of this is a bit confusing; we’re not actually squaring anything, but this notational weirdness is an accident of history. At any rate, the most straightforward, but perhaps least intuitive way of thinking about heritability is that it is the slope of the best-fit linear regression of offspring trait means on parent trait means. If your parents’ mean height is x, and you and your siblings’ mean height is y, and you plot this as a point (x,y) on a coordinate plane along with those of many other families, heritability is the slope of the line that most closely follows this cluster of points. Incidentally, the technique of linear regression taught in introductory statistics was developed for just this purpose.


How Do You Get Adolescents to Meditate?

a person sitting quietly in a meditation poseIn the health behavior field, we often focus on what health professionals should help young people avoid, such as risk behaviors, rather than positive health behaviors that we could help them acquire. So, when I decided to start working on my PhD, and I wanted to study health promoting behaviors, I knew I would be met with some resistance or challenges from the more well established health behavior researchers.  Fortunately, I ended up at Indiana University where this type of thinking is not only accepted, but encouraged within the Applied Health Science Department.

The adolescent period has traditionally been viewed as a time in life to ‘just survive’.  Remember the three As of adolescence- Acne, Awkward, and Apathetic.  However, due to advances in neuroscience, researchers are now singing a different tune when studying adolescents.  Traditionally, it was thought that a majority of the development that occurs in the brain happens during early childhood.  The neuroimaging studies from the last 10-15 years suggest otherwise (Giedd, 2008).  Around age 12, the brain goes through another massive restructuring as it eliminates connections between brain cells that aren’t used and strengthens those that are.   (more…)

Nanomaterials that Inhibit Bacterial Growth

Nanomaterials are fast becoming the materials of the future. Just this year three scientists were awarded the Nobel Prize in Chemistry for their work in understanding Molecular Machines. Each time period in human history has been defined by the materials that we are able to harness–the Stone Age, the Bronze Age, and now, the Nanomaterial Age? The better scientists are able to design, create, and manipulate nanoscale objects, the more advanced our technology will become.

But let’s back up a little. What is the nanoscale? You would be correct if you said really, really, really small, but let’s be more precise about it. A nanometer is 0.000000001 meters or, in scientific notation, 1 × 10-9 meters (move the decimal over 9 spaces). As you can see from the image below, you can’t see nanoscale objects with the naked eye, but they are still much bigger than individual molecules or x-rays. (more…)

The Lessons of Science Past—Learning about the History of Science

The logo of the Junto. It is a set of concentric circles labeled with the names of different states in the Midwest of the United States. It mirrors a geocentric cosmological diagram (with the earth at the center) in Peter Apian's Cosmographia, 1524.
Even though the geocentric model of our universe is outdated, it is still useful for illustrating the burdens facing many young scholars in the U.S. Midwest. Moving to a new location each year, the Junto makes it easier for historians of science to get out of the seemingly “outer orbit” of the Midwest by bringing the “center of the universe” to them. Logo modeled on a diagram in Peter Apian’s Cosmographia, 1524.

As a reader on this blog, you probably enjoy learning about science.  But how much do you know about its history?  If you’re a scientist, do you know where your field came from?  There are fascinating stories behind the instruments you use and the journals you read.  If you’re not a scientist, do you know about the connections between surgery and warfare?  Or how computers came to be both everywhere and invisible?  This is where historians of science come in.  We inform current-day scientists by tracing their present work to past discoveries and reflecting on the lessons from these successes and failures.  We can tell you how scientific knowledge has changed over time, the stories of the people who were behind it, and how it shaped and was shaped by society.   (more…)

Why is there no cure for cancer, and what are we doing about it?

Have you ever wondered why there is no “cure” for cancer? Conspiracy theories aside, a cure for cancer doesn’t exist because it is biologically impossible. The reason is simple: just as no two people are identical, no two cancers are the same. Each case of cancer may be genetically distinct, which means that the driver mutations that caused the cancer  can differ from patient to patient. For this reason, different treatments are required for each type of cancer, making it unfeasible to think that there will someday be a “one-size-fits-all” cure for cancer.

Given such diversity among cancers, what is the best strategy for scientists to target specific driver mutations? Treatments that are tailored to a specific mutational subtype of a disease are called precision medicines. Precision medicines are designed with consideration of a patient’s genetics, lifestyle, and environment in order to more effectively treat individual cancer cases.  In 2016, President Obama launched a $215 million Precision Medicine Initiative to fund advances in this area. (more…)

The Need of Our Times: Support for Fundamental Science Research

If you are an undergraduate student, you probably share some attributes with other readers of this blog. You are likely a millennial, meaning that you may not remember the fall of the Berlin wall, and to you, the space race is a distant past. It is also likely that you do not remember an era when scientists focused mainly on their work, instead of on how to secure the funding.

Graphic comparing federal funding shares and dollar amounts for science research and development (y-axis) by fiscal year, from 1960 to 2014 (x-axis).
Figure 1: Federal research and development (R&D) spending peaked in 1965, but has been decreasing since then. Though the total amount of federal spending (total outlays in federal budget) has increased dramatically, R&D spending has maintained a level below 5% for the majority of the last two decades. [click to enlarge]
Federal funding for “fundamental” or “basic” science research was at the all-time high in the 1960’s (see Figure 1). However, it has not increased in the recent past and, worse, has steadily declined. At a time when the science, technology, engineering, and math (STEM) workforce is forecast to hit a new peak, this should be alarming. Consumers love 21st-century technologies, like smartphones and smart TVs, but what will 22nd-century technology look like with diminished federal funding? Because we regularly hear about budget cuts and are surrounded by economic uncertainty, we fail to recognize that science funding in the U.S. is not keeping up with that of other countries (see Figure 2 below). (more…)

Chemical Keys to Brain Function

According to both popular science and drug commercials, the brain is a mess of chemicals.  Imbalances in these chemicals are responsible for a variety of ailments from depression to addiction. However, there’s rarely any mention of how these chemicals are related to neural activity. For instance, why is dopamine often rewarding, and why is serotonin related to depression?

A molecule of glutamate depicted as differently colored spheres representing atoms connected by cylinders representing molecular bonds.
The molecular structure of glutamate, an excitatory neurotransmitter. Glutamate unlocks “doors” in many neurons that allow charged particles into the cell, making it more likely to fire. Image by SubDural12 / CC BY.

To answer such questions, let’s back up a bit. The brain receives, processes, and sends information in the form of electrical signals sent to and from neurons. Like all cells, neurons have a membrane which separates the inside of the cell from the outside. They also have molecular machinery that keeps the inside of the cell more electrically negative than the outside of the cell by pumping out certain electrically charged particles and allowing others in. Like a wall in a building, the membrane is solid in most places but also contains tiny doors. When the right molecule fits into part of the door, like a key into a lock, the door opens and lets in particles which can make the inside more or less negative.