Applied Research Briefs

Estrogen’s Impact on Post-traumatic Emotional Experiences

by Karuna Meda, Merrill Meadow | Illustrations by Jamie Cullen

Stress is common in many people’s lives and it can make straightforward tasks challenging. In fact, stress can affect both the way we think and how our bodies function.

Psychology researcher Jenna Rieder, PhD, studies how chronic stress and trauma interact with physiology. “I am particularly interested in how stress-related changes in the body connect with outcomes like risk for mental illness,” she says.

In one recent study, she and colleagues at the University of Nevada assessed how the hormone estradiol impacts everyday emotions of women who have experienced trauma. Fluctuations in estradiol have been linked to mood, cognition and the body’s stress response. “But it’s unclear if estradiol levels can affect the emotions of women who have experienced traumatic events,” says Dr. Rieder.

Her team showed that among women exposed to trauma, daily emotional experiences — including symptoms of post-traumatic stress disorder (PTSD) — differed by menstrual cycle phase. They found that participants experienced more PTSD symptoms and greater mood changes during days of lower estradiol levels.

These results might help clinicians anticipate when symptoms increase in their trauma-exposed patients who menstruate, and could also guide patients’ own responses to stress.

“Stress is often viewed as purely psychological,” says Dr. Rieder. “I hope that our studies help people recognize how stress is linked to our natural biology and physical health.”

The Inner Life of Ocean Waves 

by Karuna Meda, Merrill Meadow | Illustrations by Jamie Cullen

For many, watching ocean waves roll to shore provides fascination and joy. Others, however, are absorbed by ocean waves that flow underneath, transferring heat, energy and nutrients throughout the ocean.

“The ocean is stratified, with heavy cold water below and light warm water above,” says physicist Edward Santilli, PhD. “But there are lots of interactions between these layers, which spur ‘internal waves’ that can flow many kilometers before they become turbulent and dissipate.”

That turbulence affects the ocean, the atmosphere — and, ultimately, us.

About two hundred feet down, a change in the water’s density blocks anything from traveling up from the abyss or down from the shallow ocean. “But turbulent mixing breaks through that wall, allowing nutrients to rise into shallow waters and carbon dioxide absorbed from the atmosphere to descend into the abyss,” Dr. Santilli explains.

The SOMAR model uses adaptive grids to calculate mixing at the interface of two water densities. As the heavy (red) fluid moves to the left and the light (blue) fluid moves to the right, the fluid in between overturns and mixes (yellows and greens).

Just how many nutrients and how much carbon dioxide do internal waves exchange? That is challenging for researchers to quantify. “In the actual ocean, that process would require plenty of equipment,” Dr. Santilli says. “So, we look to computer simulations. Unfortunately, no modern computer is powerful enough to capture the enormous range of scales of internal waves.”

So, Dr. Santilli created the Stratified Ocean Model with Adaptive Refinement (SOMAR), which works on a simple principle: At any given time most of the ocean is not turbulent, therefore an efficient model rarely needs to capture very small-scale motions. SOMAR models large-scale motions only, at least until it detects turbulence. Then it triggers a data-intensive small-scale model that feeds information back to the large-scale model. Once that data has been incorporated, the turbulence model ceases and the large-scale model resumes — until new turbulence is detected.

Dr. Santilli and his collaborators hope to use SOMAR to develop a model of internal wave mixing. Such a model would facilitate more accurate investigations of microbial lifecycles and global weather patterns.