Understanding what contributes to patients’ inactivity is the focus of a world first study from the University of South Australia. Here, researchers have found that people with knee OA unconsciously believe that activity may be dangerous to their condition, despite medical advice telling them otherwise.

The study found that of those surveyed, 69% of people with knee pain had stronger implicit (unconscious) beliefs that exercise was dangerous than the average person without pain.

It’s an interesting finding that not only highlights the conflicted nature of pain and exercise, but also that what people say and what people think, deep down, may be entirely different things.

Lead researcher, and UniSA PhD candidate based at SAHMRI, Brian Pulling, says the research provides valuable insights for clinicians treating people with knee OA.

“Research shows that physical activity is good for people with knee OA, but most people with this condition do not move enough to support joint or general health,” Pulling says.

“To understand why people with OA might not be active, research studies typically use questionnaires to assess fear of moving. But unfortunately, questionnaires are limited — what we feel deep down (and how our system naturally reacts to something that is threatening) may be different to what we report. And we still know that many people are avoiding exercise, so we wanted to know why.”

To assess this, the researchers developed a tool that can detect and evaluate people’s implicit beliefs about exercise; that is, whether they unconsciously think activity is dangerous for their condition.

“We found that that even among those who said they were not fearful about exercise, they held unconscious beliefs that movement was dangerous,” Pulling says.

“Our research shows that people have complicated beliefs about exercise, and that they sometimes say one thing if asked directly yet hold a completely different implicit belief.

“People are not aware that what they say doesn’t match what they choose on the new task; they are not misrepresenting their beliefs.

“This research suggests that to fully understand how someone feels about an activity, we must go beyond just asking directly, because their implicit beliefs can sometimes be a better predictor of actual behaviour than what people report. That’s where our tool is useful.”

The online implicit association test presents a series of words and images to which a participant must quickly associate with being either safe or dangerous. The tool intentionally promotes instant responses to avoid deliberation and other influencing factors (such as responding how they think they should respond).

Associate Professor Tasha Stanton says that the new tool has the potential to identify a group of people who may have challenges increasing their activity levels and undertaking exercise.

“What people say and what people do are often two different things, Assoc Prof Stanton says.

“Having access to more accurate and insightful information will help health professionals better support their patients to engage with activity and exercise. It may also open opportunities for pain science education, exposure-based therapy, or cognitive functional therapy…things that would not usually be considered for someone who said that they were not scared to exercise.”

Researchers are now looking to see if implicit beliefs are directly associated with behaviour and are asking for people to complete the Implicit Association Test (takes seven minutes). At the end of the test participants are given their results in comparison to the rest of the population.

To take the test, please click here: https://unisasurveys.qualtrics.com/jfe/form/SV_0OZKUqzBNtiKGF0

A team of researchers led by University of Wisconsin-Madison astronomy professor Catherine Grier and recent graduate Robert Wheatley revealed the accelerating gas using years of data collected from a quasar, a particularly bright and turbulent kind of black hole, billions of light years away in the constellation Boötes. They presented their findings today at the 244th meeting of the American Astronomical Society in Madison.

Scientists believe black holes are situated at the center of most galaxies. Quasars are supermassive black holes surrounded by disks of matter being pulled in by the black hole’s enormous gravitational power.

“The material in that disk is always falling into the black hole, and the friction of that pulling and pulling heats up the disk and makes it very, very hot and very, very bright,” says Grier. “These quasars are really luminous, and because there’s a large range of temperatures from the interior to the far parts of the disk, their emission covers almost all of the electromagnetic spectrum.”

The bright light makes quasars nearly as old as the universe (as many as 13 billion light years away) visible, and the broad range of their radiation makes them particularly useful for astronomers to probe the early universe.

Researchers used more than eight years of observations of a quasar called SBS 1408+544, collected by a program carried out by the Sloan Digital Sky Survey now known as the Black Hole Mapper Reverberation Mapping Project. They tracked winds composed of gaseous carbon by spotting light from the quasar that was missing — light that was being absorbed by the gas. But instead of being absorbed at exactly the right spot in the spectrum that would indicate carbon, the shadow shifted farther from home with every new look at SBS 1408+544.

“That shift tells us the gas is moving fast, and faster all the time,” says Wheatley. “The wind is accelerating because it’s being pushed by radiation that is blasted off of the accretion disk.”

Scientists, including Grier, have suggested they’ve observed accelerating winds from black hole accretion disks before, but this had not yet been backed by data from more than a few observations. The new results came from about 130 observations of SBS 1408+544 made over nearly a decade, which allowed the team to solidly identify the increase in velocity with high confidence.

The winds pushing gas out from the quasar are of interest to astronomers because they are a way in which the supermassive black holes might influence the evolution of the galaxies that surround them.

“If they’re energetic enough, the winds may travel all the way out into the host galaxy, where they could have a significant impact,” Wheatley says.

Depending on the circumstances, a quasar’s winds could supply pressure that squeezes gas together and speeds the birth of a star in its host galaxy. Or it could scour away that fuel and keep a potential star from forming.

“Supermassive black holes are big, but they’re really tiny compared to their galaxies,” says Grier, whose work is supported by the National Science Foundation. “That doesn’t mean they can’t ‘talk’ to each other, and this is a way for one to talk to the other that we will have to account for when we model the effects of these kinds of black holes.”

The study of SBS 1408+544, published today in The Astrophysical Journal included collaborators at York University, Pennsylvania State University, University of Arizona and others.

This research was funded in part by grants from the National Science Foundation (AST-2310211 and AST-2309930).

The research comprises two papers, one published in The Astrophysical Journal in April 2024, and one as yet unpublished that will be submitted to the same journal. The results will be presented at the 244th meeting of the American Astronomical Society, held June 9 through June 13 at the Monona Terrace Convention Center in Madison, Wisconsin. 

“Supermassive black holes in galaxy centers have millions-to-billions of times the mass of the Sun,” said Fan Zou, a graduate student at Penn State and first author of the papers. “How do they become such monsters? This is a question that astronomers have been studying for decades, but it has been difficult to track all the ways black holes can grow reliably.”

Supermassive black holes grow through a combination of two main channels. They consume cold gas from their host galaxy — a process called accretion — and they can merge with other supermassive black holes when galaxies collide.

“During the process of consuming gas from their hosting galaxies, black holes radiate strong X-rays, and this is the key to tracking their growth by accretion,” said W. Niel Brandt, Eberly Family Chair Professor of Astronomy and Astrophysics and professor of physics at Penn State and a leader of the research team. “We measured the accretion-driven growth using X-ray sky survey data accumulated over more than 20 years from three of the most powerful X-ray facilities ever launched into space.”

The research team used complementary data from NASA’s Chandra X-ray Observatory, the European Space Agency’s X-ray Multi-Mirror Mission-Newton (XMM-Newton), and the Max Planck Institute for Extraterrestrial Physics’ eROSITA telescope. In total, they measured the accretion-driven growth in a sample of 1.3 million galaxies that contained over 8,000 rapidly growing black holes.

“All of the galaxies and black holes in our sample are very well characterized at multiple wavelengths, with superb measurements in the infrared, optical, ultraviolet, and X-ray bands,” Zou said. “This allows for robust conclusions, and the data show that, at all cosmic epochs, more massive galaxies grew their black holes by accretion faster. With the quality of the data, we were able to quantify this important phenomenon much better than in past works.”

The second way that supermassive black holes grow is through mergers, where two supermassive black holes collide and merge together to form a single, even more massive, black hole. To track growth by mergers, the team used IllustrisTNG, a set of supercomputer simulations that model galaxy formation, evolution, and merging from shortly after the Big Bang until the present.

“In our hybrid approach, we combine the observed growth by accretion with the simulated growth through mergers to reproduce the growth history of supermassive black holes,” Brandt said. “With this new approach, we believe we have produced the most realistic picture of the growth of supermassive black holes up to the present day.”

The researchers found that, in most cases, accretion dominated black-hole growth. Mergers made notable secondary contributions, especially over the past 5 billion years of cosmic time for the most-massive black holes. Overall, supermassive black holes of all masses grew much more rapidly when the Universe was younger. Because of this, the total number of supermassive black holes was almost settled by 7 billion years ago, while earlier in the Universe many new ones kept emerging.

“With our approach, we can track how central black holes in the local universe most likely grew over cosmic time,” Zou said. “As an example, we considered the growth of the supermassive black hole in the center of our Milky Way Galaxy, which has a mass of 4 million solar masses. Our results indicate that our Galaxy’s black hole most likely grew relatively late in cosmic time.”

In addition to Zou and Brandt, the research team includes Zhibo Yu, graduate student at Penn State; Hyungsuk Tak, assistant professor of statistics and of astronomy and astrophysics at Penn State; Elena Gallo at the University of Michigan; Bin Luo at Nanjing University in China; Qingling Ni at the Max Planck Institute for Extraterrestrial Physics in Germany; Yongquan Xue at the University of Science and Technology of China; and Guang Yang at the University of Groningen in the Netherlands.

Funding from the U.S. National Science Foundation, the Chandra X-ray Center, and Penn State supported this work. The work was also made possible by the sharing of the IllustrisTNG simulation results with the scientific community.