In research published today in Nature Mental Health, an international team of researchers, including from the University of Cambridge and Fudan University, looked at a combination of factors including lifestyle factors, genetics, brain structure and our immune and metabolic systems to identify the underlying mechanisms that might explain this link.

According to the World Health Organization, around one in 20 adults experiences depression, and the condition poses a significant burden on public health worldwide. The factors that influence the onset of depression are complicated and include a mixture of biological and lifestyle factors.

To better understand the relationship between these factors and depression, the researchers turned to the UK Biobank, a biomedical database and research resource containing anonymised genetic, lifestyle and health information about its participants.

By examining data from almost 290,000 people — of whom 13,000 had depression — followed over a nine-year period, the team was able to identify seven healthy lifestyle factors linked with a lower risk of depression. These were:

• moderate alcohol consumption
• healthy diet
• regular physical activity
• healthy sleep
• never smoking
• low-to-moderate sedentary behaviour
• frequent social connection

Of all of these factors, having a good night’s sleep — between seven and nine hours a night — made the biggest difference, reducing the risk of depression, including single depressive episodes and treatment-resistant depression, by 22%.

Frequent social connection, which in general reduced the risk of depression by 18%, was the most protective against recurrent depressive disorder.

Moderate alcohol consumption decreased the risk of depression by 11%, healthy diet by 6%, regular physical activity by 14%, never smoking by 20%, and low-to-moderate sedentary behaviour by 13%.

Based on the number of healthy lifestyle factors an individual adhered to, they were assigned to one of three groups: unfavourable, intermediate, and favourable lifestyle. Individuals in the intermediate group were around 41% less likely to develop depression compared to those in the unfavourable lifestyle, while those in the favourable lifestyle group were 57% less likely.

The team then examined the DNA of the participants, assigning each a genetic risk score. This score was based on the number of genetic variants an individual carried that have a known link to risk of depression. Those with the lowest genetic risk score were 25% less likely to develop depression when compared to those with the highest score — a much smaller impact than lifestyle.

In people at high, medium, and low genetic risk for depression, the team further found that a healthy lifestyle can cut the risk of depression. This research underlines the importance of living a healthy lifestyle for preventing depression, regardless of a person’s genetic risk.

Professor Barbara Sahakian, from the Department of Psychiatry at the University of Cambridge, said: “Although our DNA — the genetic hand we’ve been dealt — can increase our risk of depression, we’ve shown that a healthy lifestyle is potentially more important.

“Some of these lifestyle factors are things we have a degree control over, so trying to find ways to improve them — making sure we have a good night’s sleep and getting out to see friends, for example — could make a real difference to people’s lives.”

To understand why a healthy lifestyle might reduce the risk of depression, the team studied a number of other factors.

First off, they examined MRI brain scans from just under 33,000 participants and found a number of regions of the brain where a larger volume — more neurons and connections — was linked to a healthy lifestyle. These included the pallidum, thalamus, amygdala and hippocampus.

Next, the team looked for markers in the blood that indicated problems with the immune system or metabolism (how we process food and produce energy). Among those markers found to be linked to lifestyle were the C-reactive protein, a molecule produced in the body in response to stress, and triglycerides, one of the primary forms of fat that the body uses to store energy for later.

These links are supported by a number of previous studies. For example, exposure to stress in life can affect how well we are able to regulate blood sugar, which may lead to a deterioration of immune function and accelerate age-related damage to cells and molecules in the body. Poor physical activity and lack of sleep can damage the body’s ability to respond to stress. Loneliness and lack of social support have been found to increase the risk of infection and increase markers of immune deficiency.

The team found that the pathway from lifestyle to immune and metabolic functions was the most significant. In other words, a poorer lifestyle impacts on our immune system and metabolism, which in turn increases our risk of depression.

Dr Christelle Langley, also from the Department of Psychiatry at the University of Cambridge, said: “We’re used to thinking of a healthy lifestyle as being important to our physical health, but it’s just as important for our mental health. It’s good for our brain health and cognition, but also indirectly by promoting a healthier immune system and better metabolism.”

Professor Jianfeng Feng, from Fudan University and Warwick University, added: “We know that depression can start as early as in adolescence or young adulthood, so educating young people on the importance of a healthy lifestyle and its impact on mental health should begin in schools.”

This study was supported by grants from organisations including the National Natural Science Foundation of China and the Ministry of Science, China*.

Adnan Rajib, a UT Arlington assistant professor in the Department of Civil Engineering, was the lead author on the published study, “Human Alterations of the Global Floodplains.”His doctoral student, Qianjin Zheng, played a significant role in developing the research.

U.S. Environmental Protection Agency (EPA) scientists Charles Lane, Heather Golden and Jay Christensen; Itohaosa Isibor of Texas A&M University-Kingsville; and Kris Johnson of The Nature Conservancy collaborated on the study. The work was funded through NASA and the National Science Foundation.

“The bottom line is that the world is at greater flood risk than what we realized, especially considering what effect human development has had on floodplains,” Rajib said. “In 27 years, between 1992 and 2019, the world has lost a dramatic 600,000 square kilometers of floodplains due to human disturbances, which include infrastructure development, industry and business construction and expansion of agriculture.”

The team used satellite remote sensing data and geospatial analytics in studying 520 major river basins of the world, discovering previously unknown spatial patterns and trends of human floodplain alterations.

“Mapping the world’s floodplains is relatively new. While there is increasing awareness to map floodplains accurately and understand flood risks, an attempt to map human disturbances in those floodplains at a global scale never existed,” said Rajib, who also is the director of the UT Arlington Hydrology and Hydroinformatics Innovation Lab. “It’s been done in smaller regions around the world and certainly in the United States and Europe, but not in data-poor regions of the world.”

The study concludes that wetland habitats are in danger and that one-third of the total global loss of floodplain wetlands occurred in North America. Rajib said the magnitude of risk for floodplains is much larger than what was previously understood. He and the team examined satellite pictures of those floodplain areas taken over the past 27 years.

“We wanted to look at floodplains at the neighborhood level,” Zheng said. “We wanted to see the impact of development on someone who lives adjacent to or near a floodplain. Some of the changes in these pictures are good, like when trees are planted or parks are built. But many of the pictures reveal disturbing outcomes. For instance, we saw a dramatic increase in the development of parking lots or the construction of buildings without adequate stormwater runoff allowances.”

Johnson, a co-author on the paper, said that “worldwide, floodplains are biodiversity hotspots that also provide a wide range of ecosystem services for people. We hope this study sheds light on this critical habitat we’re losing as well as ways in which we can reverse the trend.”

Melanie Sattler, chair and professor of the Department of Civil Engineering, said this study should give planners a vital tool to reduce flood risks for people.

“Rajib’s work can be our lens to help guide future development in order to decrease susceptibility to floods in a changing climate,” Sattler said. “And, in some cases, we hope this study can help us correct mistakes we’ve made through past development decisions.”

That belief is reflected in his team’s new publication in the journal Advanced Sustainable Systems.

Rabnawaz and his colleagues showed that sodium chloride — table salt — can outperform much more expensive materials being explored to help recycle plastics.

“This is really exciting,” Rabnawaz said. “We need simple, low-cost solutions to take on a big problem like plastics recycling.”

Although plastics have historically been marketed as recyclable, the reality is that nearly 90% of plastic waste in the United States ends up in landfills, in incinerators or as pollution in the environment.

One of the reasons plastics have become so disposable is that the materials recovered from recycling aren’t valuable enough to spend the money and resources required to get them.

According to the team’s projections, table salt could flip the economics and drastically reduce costs when it comes to a recycling process known as pyrolysis, which works through a combination of heat and chemistry.

Although Rabnawaz expected salt to have an impact because of how well it conducts heat, he was still surprised by how well it worked. It outperformed expensive catalysts — chemicals designed to spur reactions along — and he believes his team has just started tapping into its potential.

Furthermore, the work is already getting attention from big names in industry, he said.

In fact, the research was partially supported by Conagra Brands, a consumer packaged goods company. The U.S. Department of Agriculture and MSU AgBioResearch also helped finance the work.

A catalyst worth its salt

Pyrolysis is a process that breaks down the plastics into a mixture of simpler, carbon-based compounds, which come out in three forms: gas, liquid oil and solid wax.

That wax component is often undesirable, Rabnawaz said, yet it can account for more than half of products, by weight, of current pyrolysis methods. That’s even when using catalysts, which are helpful, but they often can be toxic or prohibitively expensive to be applied in managing waste plastics.

Platinum, for example, has very attractive catalytic properties, which is why it’s used in catalytic converters to reduce harmful emissions from cars. But it’s also very pricey, which is why thieves steal catalytic converters.

Although bandits are unlikely to rob platinum-based materials from a sweltering pyrolysis reactor, attempting to recycle plastics with those catalysts would still require a hefty investment — millions, if not hundreds of millions, of dollars, Rabnawaz said. And current catalysts aren’t efficient enough to justify that cost.

“No company in the world has that kind of cash to burn,” Rabnawaz said.

In earlier work, Rabnawaz and his team showed that copper oxide and table salt worked as catalysts to break down a plastic known as polystyrene. Now, they’ve shown table salt alone can eliminate the wax byproduct in the pyrolysis of polyolefins — polymers that account for 60% of plastic waste.

“That first paper was important, but I didn’t get excited until we worked with polyolefins,” Rabnawaz said. “Polyolefins are huge, and we just outperformed expensive catalysts.”

Joining Rabnawaz on this project were Christopher Saffron, an associate professor in the College of Agriculture and Natural Resources, visiting scholar Mohamed Shaker and MSU doctoral student Vikash Kumar.

When using table salt as a catalyst to pyrolyze polyolefins, the team produced mostly liquid oil containing hydrocarbon molecules similar to what’s found in diesel fuel, Rabnawaz said. Another perk of the salt catalyst, the researchers showed, is it can be reused.

“You can recover salt by simply washing the obtained oil with water,” Rabnawaz said.

The researchers also showed that table salt aided in the pyrolysis of metallized plastic films, which are commonly used in food packaging, like potato chip bags, which isn’t currently recycled.

Although pure table salt didn’t outperform a platinum-alumina catalyst the team also tested with metallized films, the results were similar, and the salt is a fraction of the cost.

Rabnawaz, however, stressed that metallized films, while useful, are inherently problematic. He envisions a world where such films are no longer needed, which is why his team is also working to replace them with more sustainable materials.

The team will also continue working to further its pyrolysis project.

For instance, the team has yet to fully characterize the gas products of pyrolysis with table salt. And Rabnawaz believes the team can improve this approach so that the liquid products contain chemicals with more valuable applications than being burned as fuel.

Still, the early returns of the team’s new table salt tactics are encouraging. Based on a quick, preliminary economic analysis, the team estimated a commercial pyrolysis reactor could triple its profits just by adding salt.

Cold Spring Harbor Laboratory (CSHL) Professor Christopher Hammell has found that in the worm C. elegans, this genetic orchestra has no single conductor. Instead, a quartet of molecules works in concert to time each developmental stage. Hammell says this process shares some similarities with the circadian clocks that control human behavior. Understanding how the worm’s clock is regulated could help explain how time affects development in other animals. Hammell explains:

“This clock we’ve discovered sets the cadence of development. It’s a coordinator of the orchestra. It controls when the trombone goes, how loud it gets, and how long the note lasts.”

Each stage of C. elegans‘ development begins with two proteins, NHR-85 and NHR-23. They work together to spark a pulse of gene expression, switching on the microRNA lin-4, which controls stem cell development patterns. The pulse’s timing, strength, and duration depend on the short stretch when NHR-85 and NHR-23 interact, and another protein, LIN-42, which ends each developmental period by shutting off NHR-85.

“Mess up the orchestra — it’ll still make sound,” Hammell says. “But the way the music changes lets us know proper timing is critical for development.”

Hammell teamed with Wolfgang Keil from Paris’ Curie Institute to observe this gene expression cycle in action. C. elegans takes about 50 hours to reach adulthood. During that time, it’s always on the move, like a restless teenager. The team developed a new imaging technique to hold the tiny worm in place long enough to take pictures and video. This let them measure each developmental beat as it occurred.

“We could see every time genes turned on from birth to adulthood,” Hammell says. “This kind of imaging had never been done in animals, only in single cells.”

Hammell is now working with CSHL Professor & HHMI Investigator Leemor Joshua-Tor to image how clock proteins interact over time.

“We want to work out, with even more precision, how this clock operates,” Hammell says. “Humans can do things like write music or perform calculus, not because we have a calculus or music gene, but because our developmental clocks enable our brain to develop longer into a more complex organ.”

In other words, when it comes to development, time is truly of the essence.

“In our earlier work, we demonstrated that our soft robot was able to twist and turn its way through a very simple obstacle course,” says Jie Yin, co-corresponding author of a paper on the work and an associate professor of mechanical and aerospace engineering at North Carolina State University. “However, it was unable to turn unless it encountered an obstacle. In practical terms this meant that the robot could sometimes get stuck, bouncing back and forth between parallel obstacles.

“We’ve developed a new soft robot that is capable of turning on its own, allowing it to make its way through twisty mazes, even negotiating its way around moving obstacles. And it’s all done using physical intelligence, rather than being guided by a computer.”

Physical intelligence refers to dynamic objects — like soft robots — whose behavior is governed by their structural design and the materials they are made of, rather than being directed by a computer or human intervention.

As with the earlier version, the new soft robots are made of ribbon-like liquid crystal elastomers. When the robots are placed on a surface that is at least 55 degrees Celsius (131 degrees Fahrenheit), which is hotter than the ambient air, the portion of the ribbon touching the surface contracts, while the portion of the ribbon exposed to the air does not. This induces a rolling motion; the warmer the surface, the faster the robot rolls.

However, while the previous version of the soft robot had a symmetrical design, the new robot has two distinct halves. One half of the robot is shaped like a twisted ribbon that extends in a straight line, while the other half is shaped like a more tightly twisted ribbon that also twists around itself like a spiral staircase.

This asymmetrical design means that one end of the robot exerts more force on the ground than the other end. Think of a plastic cup that has a mouth wider than its base. If you roll it across the table, it doesn’t roll in a straight line — it makes an arc as it travels across the table. That’s due to its asymmetrical shape.

“The concept behind our new robot is fairly simple: because of its asymmetrical design, it turns without having to come into contact with an object,” says Yao Zhao, first author of the paper and a postdoctoral researcher at NC State. “So, while it still changes directions when it does come into contact with an object — allowing it to navigate mazes — it cannot get stuck between parallel objects. Instead, its ability to move in arcs allows it to essentially wiggle its way free.”

The researchers demonstrated the ability of the asymmetrical soft robot design to navigate more complex mazes — including mazes with moving walls — and fit through spaces narrower than its body size. The researchers tested the new robot design on both a metal surface and in sand.

“This work is another step forward in helping us develop innovative approaches to soft robot design — particularly for applications where soft robots would be able to harvest heat energy from their environment,” Yin says.

The work was done with support from the National Science Foundation under grants 2005374, 2126072, 1944655 and 2026622.

Synchronised phenomena are all around us, whether it is human clapping and dancing, or the way fireflies flash, or how our neurons and heart cells interact. However, it is something not fully understood in engineering and science.

Associate Professor Joseph Lizier, expert in complex systems at the University of Sydney, said: “We know the feeling of dancing in step to the ‘Nutbush’ in a crowd — or the awkward feeling when people lose time clapping to music. Similar processes occur in nature, and it is vital that we better understand how falling in and out of sync actually works.

“Being in sync in a system can be very good; you want your heart cells to all beat together rather than fibrillate. But being in sync can also be very bad; you don’t want your brain cells to all fire together in an epileptic seizure.”

Associate Professor Lizier and colleagues at the Max Planck Institute in Leipzig, Germany have published new research on synchronisation in the Proceedings of the National Academy of Sciences (PNAS).

The paper sets out the mathematics of how the network structure connecting a set of individual elements controls how well they can synchronise their activity. It is a critical insight into how these systems operate, because in most real-world systems, no one individual element controls all the others. And nor can any individual directly see and react to all the others: they are only connected through a network.

Associate Professor Lizier, from the Centre of Complex Systems and the School of Computer Science in the Faculty of Engineering, said: “Our results open new opportunities for designing network structures or interventions in networks. This could be super useful in stabilising electricity in power grids, vital for the transition to renewables, or to avoid neural synchronisation in the brain, which can trigger epilepsy.”

To understand how these systems work, the researchers studied what are known as “walks” through a network in a complex system. Walks are sequences of connected hops between individual elements or nodes in the network.

Associate Professor Lizier said: “Our maths examines paired walks: where you start at one node and set off on two walks with randomly chosen hops between nodes for a specified number of steps. Those two walks might end up at the same node (convergent walks) or at different nodes (divergent walks).

“Our main finding is that the more commonly paired walks on a network are convergent, the worse the quality of synchronisation on that network structure would be.”

This is good news for the brain, where synchronisation is not desirable as it can cause epilepsy . The brain’s highly modular structure means it has a high proportion of convergent walks, which naturally push it away from epilepsy.

“We can even draw an analogy to social media with the echochamber phenomenon,” said co-author Jürgen Jost, whose group also works on social network dynamics. “Here we see sub-groups reinforcing their own messages, via convergent walks within their own group, but not necessarily synchronising to the wider population.”

The findings represent a major step forward in the theory of how the structure of complex networks affects their dynamics or how they compute, such as how brain structure underpins cognition.

The research was supported by the Australian Research Council Discovery Early Career Researcher Award (DECRA) grant DE160100630, the The University of Sydney, Sydney Research Accelerator (SOAR) award, the Alexander von Humboldt Foundation and the NSF Grant Division of Mathematical Sciences (DMS)-0804454 Differential Equations in Geometry. The research used the University of Sydney’s high-performance computing cluster Artemis in generating the paper’s results for this paper.

The researchers declare no competing interests.

Bio-oils resulting from the intense heating (pyrolysis) of industrial or agricultural by-products, are increasingly seen as potential alternatives to fossil fuels. But the stability and consequent treatment of these bio-oils depends entirely on their composition; and since they are often mixtures of many dozens, or hundreds, of different compounds, analysing such complex mixtures is not simple — or cheap.

Dr Robert Evans, Senior Lecturer in Physical Chemistry at Aston University, explains: “The composition of any pyrolysis bio-oil is absolutely key to future use. For example if there are oxygen-containing chemicals in the oil, that will make the oil more corrosive and it will be more unstable. So in particular we need to know if carbonyl groups are present — where oxygen and carbon atoms are bonded together — as these can have a major impact.”

A leading method of analysis is high-field nuclear magnetic resonance (NMR) spectroscopy, which gives a detailed breakdown of the identity and concentration of chemical species present in any sample. However these large high-field NMR spectrometry machines cost in the range of £600,000-£10million and require a supply of expensive cryogens and solvents, so are generally only found in the very biggest research facilities.

The team at Aston, led by Dr Evans, set out to see if ‘low-field’, or benchtop, NMR spectrometers, could analyse pyrolysis oils well enough to produce the necessary detailed information. Benchtop NMR spectrometers use permanent magnets, which don’t require cryogenic cooling, so cost much less to purchase and maintain. However, using lower strength magnets comes at the cost of lower sensitivity and poorer resolution. While they can find some use as research instruments, they are also commonly found in teaching laboratories.

The study, carried out with collaborators at the University of Tennessee, tested pyrolysis oils produced from a number of different plants, and compared the results from benchtop spectrometers to both high-field spectrometers and other methods of analysis. They found that the benchtop machine estimates compared favourably with titration analysis for overall carbonyl content, as well as matching high-field spectrometry for the specific identification of carbonyl groups such as ketones, aldehydes and quinones.

Dr Evans said: “Despite the known limitations of benchtop spectrometers, a very similar quality of NMR data could be obtained for these samples, enough to accurately estimate concentrations of different classes of carbonyl-containing species. Using benchtop spectrometers will make NMR analysis of pyrolysis oils much simpler, cheaper, and more accessible to a wider range of different users.”