Caitlin Milera, University of North Dakota

Thirteen years before any other woman joined the National Advisory Committee for Aeronautics – or the NACA, NASA’s predecessor – in a technical role, a young lab assistant named Pearl Young was making waves in the agency. Her legacy as an outspoken and persistent advocate for herself and her team would pave the way for women in science, technology, engineering and mathematics for decades to come.

My interest in Young’s story is grounded in my own identity as a woman in a STEM field. I find strength in sharing the stories of women who made lasting impacts in STEM. I am the director of the NASA-fundedNorth Dakota Space Grant Consortium, where we aim to foster an open and welcoming environment in STEM. Young’s story is one of persistence through setbacks, advocacy for herself and others, and building a community of support.

Facing challenges from the beginning

Young was a scientist, an educator, a technical editor and a researcher. Born in 1895, she was no stranger to the barriers that women faced at the time.

In the early 20th century, college degrees in STEM fields were considered “less suited for women,” and graduates with these degrees were considered unconventional women. Professors who agreed to mentor women in advanced STEM fields in the 1940s and 1950s were often accused of communism.

In 1956, the National Science Foundation even published an article with the title: “Women are NOT for Engineering.”

Despite society’s sexist standards, Young earned a bachelor’s degree in 1919 with a triple major in physics, mathematics and chemistry, with honors, from the University of North Dakota. She then began her decades-long career in STEM.

Becoming a technical editor

Despite the hostile culture for women, Young successfully navigated multiple technical roles at the NACA. With her varied expertise, she worked in several divisions – physics, instrumentation and aerodynamics – and soon noticed a trend across the agency. Many of the reports her colleagues wrote weren’t well written enough to be useful.

In a 1959 interview, Young spoke of her start at the NACA: “Those were fruitful years. I was interested in good writing and suggested the need for a technical editor. The engineers lacked the time to make readable reports.”

Three years after voicing her suggestion, Young was reassigned to the newly created role of assistant technical editor in the publications section in 1935. After six years in that role, Young earned the title of associate technical editor in 1941.

In 1941, the NACA established the Aircraft Engine Research Laboratory, now known as NASA Glenn Research Center, in Cleveland. This new field center needed experienced employees, so two years later, NACA leadership invited Young to lead a new technical editing section there.

It was at the Aircraft Engine Research Laboratory that Young published her most notable technical work, the Style Manual for Engineering Authors, in 1943. NASA’s History Office even referred to Young as the architect of the NACA technical reports system.

Young’s style manual allowed the agency to communicate technological progress around the globe. This manual included specific formatting rules for technical writing, which would increase consistency for engineers and researchers reporting their data and experimental results. It was essential for efficient World War II operations and was translated into multiple languages.

But it wasn’t until after this publication that Young finally received the promotion to full technical editor, 11 years after she voiced the need for the role at the agency. She was the first person to hold this role, but she had to start at the assistant level, then move up to associate before receiving the full technical editor designation.

Pearl Young ‘raising hell’

Perhaps the most noteworthy piece of Young’s story is her character. While advocating for herself and her colleagues, Young often had to challenge authority.

She stood up for her editing section when male supervisors wrongfully accused them of making mistakes. She wrote official proposals to properly classify her office in the research division at the Aircraft Engine Research Laboratory. She regularly acknowledged the contributions of her entire team for the achievements they shared.

She also secured extra personnel to lessen unbearable workloads and wrote official memorandums to ensure that her colleagues earned rightful promotions. Young often referred to these actions as “raising hell.”

The archival documents I’ve analyzed indicate that Young’s performance at the NACA was exemplary throughout her career. In 1967, she was awarded the University of North Dakota’s prestigious Sioux Award in recognition of her professional achievements and service to the university.

In 1995, and again in 2014, NASA Langley Research Center dedicated a theater in her name. The new theater is located in NASA’s Integrated Engineering Services Building.

In 2015, Young was inducted into the inaugural NASA/NACA Langley Hall of Honor. But throughout her career, not all of her colleagues shared this complimentary view of Young and her work.

One of Young’s supervisors in 1930 thought it necessary to assess her “attitude” and fitness as an employee in her progress report – and justified his position by typing these additional words into the document himself.

Later that year, Young requested time off – likely for the holiday season – prompting a different supervisor to draft an official memorandum to the engineer in charge, a position akin to today’s NASA center director. He referred to Young’s “attitude” in requesting to use her vacation days.

Women not welcome in STEM

While sexism in STEM has shifted its forms over time, gender-based inequities still exist. Women in STEM frequently confront microaggressions, marginalization and hostile work environments, including unequal pay, lack of recognition and additional service expectations.

Women often lack supportive social networks and encounter other systemic barriers to career advancement, such as not being recognized as an authority figure, or the double standard of being perceived as too aggressive instead of as a leader.

Women of color, women who belong to LGBTQ+ communities and women who have one or more disabilities face even more barriers rooted in these intersectional identities.

One of the ways to combat these inequities is to call attention to systemic barriers by sharing stories of women who persisted in STEM – women like Pearl Young.

Caitlin Milera, Research Assistant Professor of Aerospace, University of North Dakota

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

Marco Ajello, Clemson University and Jonathan Zrake, Clemson University

Every galaxy has a supermassive black hole at its center, much like every egg has a yolk. But sometimes, hens lay eggs with two yolks. In a similar way, astrophysicists like us who study supermassive black holes expect to find binary systems – two supermassive black holes orbiting each other – at the hearts of some galaxies.

Black holes are regions of space where gravity is so strong that not even light can escape from their vicinity. They form when the core of a massive star collapses on itself, and they act as cosmic vacuum cleaners. Supermassive black holes have a mass a million times that of our Sun or larger. Scientists like us study them to understand how gravity works and how galaxies form.

Figuring out whether a galaxy has one or two black holes in its center isn’t as easy as cracking an egg and examining the yolk. But measuring how often these binary supermassive black holes form can help researchers understand what happens to galaxies when they merge.

In a new study, our team dug through historical astronomical data dating back over a hundred years. We looked for light emitted from one galaxy that showed signs of harboring a binary supermassive black hole system.

Galactic collisions and gravitational waves

Galaxies like the Milky Way are nearly as old as the universe. Sometimes, they collide with other galaxies, which can lead to the galaxies merging and forming a larger, more massive galaxy.

The two black holes at the center of the two merging galaxies may, when close enough, form a pair bound by gravity. This pair may live for up to hundreds of millions of years before the two black holes eventually merge into one.

Binary black holes release energy in the form of gravitational waves – ripples in space-time that specialized observatories can detect. According to Einstein’s general relativity theory, these ripples travel at the speed of light, causing space itself to stretch and squeeze around them, kind of like a wave.

Pulsar timing arrays use pulsars, which are the dense, bright cores of collapsed stars. Pulsars spin very fast. Researchers can look for gaps and anomalies in the pattern of radio waves emitted from these spinning pulsars to detect gravitational waves.

While pulsar timing arrays can detect the collective gravitational wave signal from the ensemble of binaries within the past 9 billion years, they’re not yet sensitive enough to detect the gravitational wave signal from a single binary system in one galaxy. And even the most powerful telescopes can’t image these binary black holes directly. So, astronomers have to use clever indirect methods to figure out whether a galaxy has a binary supermassive black hole in its center.

Searching for signs of binary black holes

One type of indirect method involves searching for periodic signals from the centers of active galaxies. These are galaxies that emit significantly more energy than astronomers might expect from the amount of stars, gas and dust they contain.

These galaxies emit energy from their nucleus, or center – called the active galactic nucleus. In a process called accretion, the black hole in each active galaxy uses gravity to pull nearby gas inward. The gas speeds up as it approaches the black hole’s event horizon – like how water surrounding a whirlpool moves faster and faster as it spirals inward.

As the gas heats up, it glows brightly in optical, ultraviolet and X-ray light. Active galactic nuclei are some of the most luminous objects in the universe.

Some active galactic nuclei can launch jets, which are particle beams accelerated to near the speed of light. When these jets line up with our observatories’ lines of sight, they appear extremely bright. They’re like cosmic lighthouses.

Some active galactic nuclei have periodic light signals that get bright, fade and then get bright again. This unique signal could come from the cyclical motion of two supermassive black holes inside, and it suggests to astronomers to look for a binary black hole system in that galaxy.

On the hunt for a binary black hole system

Our team studied one such active galactic nucleus, called PG 1553+153. The light from this object gets brighter and dimmer about every 2.2 years.

These periodic variations suggest that PG 1553+153 has a supermassive black hole binary inside. But a binary isn’t the only explanation for this variation. Other phenomena, such as wobbly jets or changes in the flow of material around the black hole, could also explain this pattern without the presence of a binary black hole, so we had to rule those out.

To understand whether the PG 1553+153 system’s light emission patterns came from a binary black hole, we simulated how binary supermassive black holes collect gas. Our models suggested that sometimes, when the black holes pull in gas, dense clumps of gas collect around the outside of the hole.

We calculated that the time it takes for these clumps to orbit around the two black holes should be five to 10 times longer than the time it takes for the two black holes to circle each other.

So, we finally had a clear prediction that we could test. If a binary black hole system caused the 2.2-year periodic variation in PG 1553+153, then we should also be able to see a longer pattern of variation, about every 10 to 20 years, when the clumps of gas circle around the black holes.

But to see whether this was really a pattern, we needed to watch it repeat for four to five cycles. For PG 1553+153, that would be 40 to 100 years.

Astronomers have observed the sky for hundreds of years. But the era of digital astronomy, where astronomical images are recorded on computers and saved in databases, is very recent – only since the year 2000 or so.

Before then, starting around 1850, astronomers recorded images of the sky on photographic plates. These are flat pieces of glass coated with a light-sensitive chemical layer traditionally used in photography. Many observatories around the world have photographic images of the night sky dating back to more than a hundred years ago. Before that, astronomers would sketch what the sky looked like in their notebooks.

Projects like DASCH, Digital Access to a Sky Century at Harvard, have started digitalizing photographic plates from a few observatories to make them available for scientists and nonscientists alike.

Our team learned that the DASCH database provided data on PG 1553+153 dating back to 1900 – more than 120 years. We used this dataset to see whether we could see a pattern repeating every 10 to 20 years.

Somewhat to our surprise, we found a 20-year pattern that adds more evidence to our theory that there’s a binary system at the core of PG 1553+153. The detection of this second pattern also helped us figure out that the masses of the two supermassive black holes are in a 2.5:1 ratio – with one 2½ times as large as the other – and that their orbit is nearly circular.

While this historical data makes us more confident that there are two supermassive black holes in PG 1553+153, we still can’t say for sure. The final confirmation might need to wait until pulsar timing arrays become sensitive enough to detect the gravitational waves coming from PG 1553+153.

Marco Ajello, Professor of Physics and Astronomy, Clemson University and Jonathan Zrake, Assistant Professor of Physics, Clemson University

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

Kerry E. Kaylegian, Penn State

As the H5N1 avian flu virus continues to spread in poultry flocks and dairy cattle, consumers may worry about whether the U.S. milk supply is safe to drink. According to the U.S. Food and Drug Administration, the answer is yes, as long as the milk is pasteurized.

In late November 2024, however, California regulators recalled two batches of raw, unpasteurized milk from a Fresno dairy farm after bird flu virus was detected in the milk. The dairy subsequently recalled all of its raw milk and cream products from stores due to possible bird flu contamination. State regulators placed the farm under quarantine, suspending any new distribution of its raw milk, cream, kefir, butter and cheese products produced on or after November 27.

No human bird flu cases associated with the milk were detected immediately following the recalls. But officials strongly urged buyers not to drink raw milk from the affected batches and to return it to the store where they bought it.

Despite health experts’ warning that raw milk could contain high levels of the avian flu virus, along with many other pathogens, raw milk sales are up in the U.S. Robert F. Kennedy Jr., whom President-elect Donald Trump has said he will nominate to head the Department of Health and Human Services, has asserted that raw milk “advances human health,” contrary to warnings from FDA officials and food scientists.

As an extension food scientist in a state where raw milk sales are legal, I provide technical support to help processors produce high-quality, safe dairy foods. I also like to help people understand the confusing world of pasteurization methods on their milk labels, and why experts strongly discourage consuming raw milk and products made from it.

What can make milk unsafe

Dairy products, like many foods, have inherent risks that can cause a variety of illnesses and even death. Dairy milk comes from animals that graze outdoors, live in barns and lie in mud and manure. Milk is picked up from the farm in tanker trucks and delivered to the processing plant. These environments offer numerous opportunities for contamination by pathogens that cause illness and produce organisms that make food spoil.

For example, listeria monocytogenes comes from environmental sources like soil and water. Mild infections with listeriosis cause flu-like symptoms. More serious cases are, unfortunately, too common and can cause miscarriages in pregnant women and even death in extreme cases.

Other pathogens commonly associated with dairy animals and raw milk include E. coli, which can cause severe gastrointestinal infections and may lead to kidney damage; Campylobacter, the most common cause of diarrheal illness in the U.S.; and Salmonella, which cause abdominal pain, diarrhea and other symptoms.

Keeping beverages safe with heat

In the 1860s, French microbiologist Louis Pasteur discovered that heating wine and beer killed the organisms that caused spoilage, which then was a significant problem in France.

This heating process, which became known as pasteurization, was adopted in the U.S. prior to World War II, at a time when milk was responsible for 25% of all U.S. outbreaks of foodborne illnesses. In 1973 the federal government required that all milk sold across state lines in the U.S. had to be pasteurized, and in 1987 it banned interstate sales of raw milk.

Pasteurization heats every particle of a food to a specific temperature for a continuous length of time in order to kill the most heat-resistant pathogen associated with that product. Different organisms have different responses to heat, so controlled scientific studies are required to determine what length of time at a given temperature will kill a specific organism.

Since 1924, pasteurization in the U.S. has been guided by the Grade “A” Pasteurized Milk Ordinance, a federal guidance document that is updated every two years to reflect current science and has been adopted by all 50 states. Pasteurization equipment in the U.S. must meet stringent requirements that include sanitary design, safety controls and material standards.

Pasteurization methods

Dairy processors can choose among several different types of pasteurization. When executed properly, all of these methods produce the same result: pathogen-free milk. Processors may treat milk beyond minimum times or temperatures to provide an extra margin of safety, or to reduce bacteria that can cause milk to spoil, thus increasing the product’s shelf life.

Smaller-scale processors who handle limited volumes use what are known as vat pasteurizers, also known as batch pasteurizers. Milk is pumped into a temperature-controlled tank with a stirrer, heated to a minimum of 145 degrees Fahrenheit (63 Celsius) and held there continuously for 30 minutes. Then it is cooled and pumped out of the vat.

The most common method used for commercial milk is high-temperature short-time pasteurization, which can treat large volumes of milk. Milk is pumped through a series of thin plates at high speed to reach a minimum temperature of 161 F (71 C). Then it travels through a holding tube for 15 seconds, and the temperature is checked automatically for safety and cooled.

The most complex and expensive systems are ultra-pasteurizers and ultra-high-temperature pasteurizers, which pasteurize milk in just a few seconds at temperatures above 285 F (140 C). This approach destroys many spoilage organisms, giving the milk a significantly longer shelf life than with other methods, although sometimes products made this way have more of a “cooked” flavor.

Ultra-high-temperature products are processed in a sterile environment and packaged in sterile packaging, such as lined cartons and pouches. They can be shelf-stable for up to a year before they are opened. Ultra-high-temperature packaging makes taking milk to school for lunch safe for kids every day.

Avian flu in milk

The detection of avian flu virus fragments in milk is a new challenge for the dairy industry. Scientists do not have a full picture of the risks to humans but are learning.

Research so far has shown that virus particles end up in the milk of infected cows, but that pasteurization will inactivate the virus. The FDA advises consumers not to drink raw milk because there is limited information about whether it may transmit avian flu.

The agency also is urging producers not to manufacture or sell raw milk or raw milk products, including cheese, made with milk from cows showing symptoms of illness.

Avian flu continues to appear in new species, and as of early December 2024, 57 human cases had been confirmed in the U.S. Of these, all but two were people who worked with livestock.

Two recent cases – a child in California and a teen in Canada – may indicate that young people with immature immune systems are more vulnerable than adults to the virus. With medical researchers still learning how H5N1 is transmitted, I agree with the FDA that raw milk poses risks not worth taking.

This is an updated version of an article originally published on May 17, 2024.

Kerry E. Kaylegian, Associate Research Professor of Food Science, Penn State

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