In space, there are clouds that contain gas and dust ejected from stars. Our solar system was formed 4.6 billion years ago from such a molecular cloud. Most of these dust grains were destroyed during solar system formation. However, a very small amount of the grains survived and remained intact in primitive meteorites. They are called presolar grains because they predate the solar system. I am a scientist who studies the early solar system and beyond, focusing mainly on presolar grains.

The picture is an image of such a grain taken by a scanning electron microscope. This grain is silicon carbide (SiC). The scale bar is 1 micron, or one millionth of a meter (39.37 inches). The grain was extracted from the Murchison meteorite that fell in Australia in 1969.

Scientists have investigated physical properties of the grain to determine its origin. Carbon has two stable isotopes, ¹²C and ¹³C, whose weights are slightly different from one another. The ratio between these isotopes is almost unchanged by processes taking place in the solar system such as evaporation and condensation. In contrast, nucleosynthetic processes in stars cause ¹²C/¹³C ratios to vary from 1 to over 200,000.

If this grain had originated within the solar system, its ¹²C/¹³C ratio would be 89. The ¹²C/¹³C ratio of the grain in this picture is about 55.1, which attests to its stellar origin. Together with other information about the grain, the ratio tells us that this grain formed in a type of star called an asymptotic giant branch star. The star was at the end of its life cycle when it profusely produced and expelled dust into space more than 4.6 billion years ago.

Scientists have found other types of presolar grains in meteorites, including diamond, graphite, oxides and silicates. Presolar grains like the one in the picture help researchers understand nucleosynthesis in stars, mixing of different zones in stars and stellar ejecta, and how abundances of elements and their isotopes change with time in the galaxy.

Sachiko Amari, Research Professor of Physics, Arts & Sciences at Washington University in St. Louis

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Racism steals time from people’s lives – possibly because of the space it occupies in the mind. In a new study published in the journal JAMA Network Open, our team showed that the toll of racism on the brain was linked to advanced aging, observed on a cellular level.

Black women who were more frequently exposed to racism showed stronger connections in brain networks involved with rumination and vigilance. We found that this, in turn, was connected to accelerated biological aging.

We are neuroscientists who use a variety of approaches, including self-reported data and biological measurements like brain scans, to answer our questions about the effects of stressors on the brain and body. We also use this data to inform the development of interventions to help people cope with this stress.

Why it matters

Aging is a natural process. However, stress can speed up the biological clock, making people more vulnerable to aging-related diseases, from cardiovascular disease to diabetes and dementia.

Epidemiological studies consistently show that Black people experience these aging-related health problems at an earlier age than white people. New studies also show focal effects of aging on the brain, indicating disparities in brain aging between Black and white populations.

Race-related stressors, including racial discrimination, affect the rate at which people age on a biological level. These experiences activate the stress response system and have been linked to greater activity in brain regions that process incoming threats. However, until now, researchers in our field have not understood how brain changes linked to racism contribute to accelerated aging.

Racial discrimination is a ubiquitous stressor that often goes unnoticed. It might look like a doctor questioning a Black patient’s pain level and not prescribing pain medication, or a teacher calling a Black child a “thug.” It is a constant stressor faced by Black people starting at an early age.

Rumination – reliving and analyzing an event on a loop – and vigilance, meaning being watchful for future threats, are possible coping responses to these stressors. But rumination and vigilance take energy, and this increased energy expenditure has a biological cost.

In our study of Black women, we found that more frequent racial discrimination was linked to more connectivity between two key regions. One, called the locus coeruleus, is a deep brain region that activates the stress response, promoting arousal and vigilance. The other is the precuneus, a key node of a brain network that engages when we think about our experiences and internalize – or suppress – our emotions.

These brain changes, in turn, were linked to accelerated cellular aging measured by an epigenetic “clock.” Epigenetics refers to changes that happen to our DNA from the environment. Epigenetic clocks assess how the environment affects our aging at a molecular level.

Higher clock values indicate that someone’s biological age is greater than their chronological age. In other words, the space that racist experiences occupy in people’s minds has a cost, which can shorten the lifespan.

What still isn’t known

Although we saw links between racism, brain connectivity changes and accelerated aging, we did not measure coping responses like rumination and vigilance in real time, meaning as people were experiencing them.

We also do not know how other factors such as neighborhood disadvantage, gender and sexuality intersect to influence accelerated aging and related health disparities.

What’s next

Our next steps are to use real-time measurement of everyday racism along with physiological measurements and neuroimaging to take a deeper dive into these research questions.

We want to know how different types of racial discrimination and coping styles influence brain and body responses. Understanding these issues better can bring more attention to prevention, such as programs that target implicit bias in physicians and teachers. It can also inform interventions like neuromodulation, which involves the use of external or internal devices to stimulate or inhibit brain activity. Neuromodulation can be used as a therapy aid to reduce stress.

The Research Brief is a short take on interesting academic work.

Negar Fani, Associate Professor of Psychiatry and Neuroscience, Emory University and Nathaniel Harnett, Assistant Professor of Psychiatry, Harvard University

This article is republished from The Conversation under a Creative Commons license. Read the original article.