A team of Japanese, Australian, Dutch, and Italian researchers has set a new speed record for an industry standard optical fibre, achieving 1.7 Petabits over a 67km length of fibre. The fibre, which contains 19 cores that can each carry a signal, meets the global standards for fibre size, ensuring that it can be adopted without massive infrastructure change. And it uses less digital processing, greatly reducing the power required per bit transmitted.

Macquarie University researchers supported the invention by developing a 3D laser-printed glass chip that allows low loss access to the 19 streams of light carried by the fibre and ensures compatibility with existing transmission equipment.

The fibre was developed by the Japanese National Institute of Information and Communications Technology (NICT, Japan) and Sumitomo Electric Industries, Ltd. (SEI, Japan) and the work was performed in collaboration with the Eindhoven University of Technology, University of L’Aquila, and Macquarie University.

All the world’s internet traffic is carried through optical fibres which are each 125 microns thick (comparable to the thickness of a human hair). These industry standard fibres link continents, data centres, mobile phone towers, satellite ground stations and our homes and businesses.

Back in 1988, the first subsea fibre-optic cable across the Atlantic had a capacity of 20 Megabits or 40,000 telephone calls, in two pairs of fibres. Known as TAT 8, it came just in time to support the development of the World Wide Web. But it was soon at capacity.

The latest generation of subsea cables such as the Grace Hopper cable, which went into service in 2022, carries 22 Terabits in each of 16 fibre pairs. That’s a million times more capacity than TAT 8, but it’s still not enough to meet the demand for streaming TV, video conferencing and all our other global communication.

“Decades of optics research around the world has allowed the industry to push more and more data through single fibres,” says Dr Simon Gross from Macquarie University’s School of Engineering. “They’ve used different colours, different polarisations, light coherence and many other tricks to manipulate light.”

Most current fibres have a single core that carries multiple light signals. But this current technology is practically limited to only a few Terabits per second due to interference between the signals.

“We could increase capacity by using thicker fibres. But thicker fibres would be less flexible, more fragile, less suitable for long-haul cables, and would require massive reengineering of optical fibre infrastructure,” says Dr Gross.

“We could just add more fibres. But each fibre adds equipment overhead and cost and we’d need a lot more fibres.”

To meet the exponentially growing demand for movement of data, telecommunication companies need technologies that offer greater data flow for reduced cost.

The new fibre contains 19 cores that can each carry a signal.

“Here at Macquarie University, we’ve created a compact glass chip with a wave guide pattern etched into it by a 3D laser printing technology. It allows feeding of signals into the 19 individual cores of the fibre simultaneously with uniform low losses. Other approaches are lossy and limited in the number of cores,” says Dr Gross.

“It’s been exciting to work with the Japanese leaders in optical fibre technology. I hope we’ll see this technology in subsea cables within five to 10 years.”

Another researcher involved in the experiment, Professor Michael Withford from Macquarie University’s School of Mathematical and Physical Sciences, believes this breakthrough in optical fibre technology has far-reaching implications.

“The optical chip builds on decades of research into optics at Macquarie University,” says Professor Withford. “The underlying patented technology has many applications including finding planets orbiting distant stars, disease detection, even identifying damage in sewage pipes.”

In a new study published in Nature Climate Change, environmental economists including the University of Exeter’s Professor Ben Groom found consensus between the two academic disciplines over an aspect of climate policy known as the ‘social discount rate’, with philosophers offering support for a rate of 2% — a value predominantly backed by economists, and which is in line with UN climate targets.

Social discount rates are used by governments to determine how costs and benefits that occur in the future — such as the impacts of climate mitigation projects, policies and programmes — are valued in the present.

A low discount rate places greater value on the benefits to future generations, such as those created by avoiding burning fossil fuels, and increases the costs of carbon emissions used in public investment appraisal.

The researchers analysed survey data from over 200 economists and philosophers with expertise in social discounting, who provided a range of qualitative and quantitative answers.

They found considerable agreement between the two disciplines for a long-term social discount rate of 2% and on analysing the survey data they found in each discipline the median discounting value resulted in temperature changes of around 1.4 degrees C by the end of the century, a figure in line with the UN Paris climate targets.

Small changes to the SDR have significant policy implications: the Trump administration’s increase of the SDR from 3% to 7% reducing the social cost of carbon by a factor of seven, whereas New York State’s decision to reduce its SDR to 2% rather than 3% made the social cost of carbon increase from $40 to $125 per tonne of CO₂.

The study is the first to attempt to build expert consensus on social discount rates outside the field of economics.

Expert advice — predominantly from economists — plays a key role in discounting and its application to climate policy, but the underlying ethical issues at stake fall outside most economists’ expertise.

The findings therefore strengthen economists’ arguments for a social discount rate of 2% by underpinning it with ethical concerns for the welfare of future generations and ‘intergenerational equity’.

Professor Ben Groom, Dragon Capital Chair in Biodiversity Economics at the University of Exeter said: “That economists and philosophers can agree on policy outcomes builds academic expert consensus, and the paper will help build consensus in favour of the new guidance as it works its way through the US government.

“The different perspectives of philosophers are complementary to those of economists and offer ethical checks and balances within integrated assessment models to narrow the set of acceptable climate policies, or offer altogether different procedural lenses through which to evaluate climate policy. These insights will be overlooked if economists continue to dominate the social discounting debate.”

The study, published in the latest issue of the journal Gerontologist, is the first to longitudinally track sexual satisfaction in tandem with sexual health and cognition, the researchers state, and its findings point to a potential novel risk factor for cognitive decline.

“What was unique about our approach is that we measured memory function and sexual function at each point in the longitudinal study, so we could look at how they changed together over time,” said Martin Sliwinski, professor of human development and family studies at Penn State and co-author on the study. “What we found connects to what scientists are beginning to understand about the link between life satisfaction and cognitive performance.”

The study explored the relationship between physical changes like the microvascular changes relevant for erectile function, and psychological changes, such as lower sexual satisfaction, to determine how the changes relate to cognition. They examined the shifts starting in middle age because it represents a transition period where declines in erectile function, cognition and sexual satisfaction begin to emerge.

Sliwinski added that while the team discovered a strong correlation between the three health factors, they can only speculate as to the cause.

“Scientists have found that if you have low satisfaction generally, you are at a higher risk for health problems like dementia, Alzheimer’s disease, cardiovascular disease and other stress-related issues that can lead to cognitive decline,” he said. “Improvements in sexual satisfaction may actually spark improvement in memory function. We tell people they should get more exercise and eat better foods. We’re showing that sexual satisfaction also has importance for our health and general quality of life.”

For the study, the researchers used survey data from 818 men who participated in the Vietnam Era Twin Study of Aging. Through neuropsychological tests, such as tests of memory and processing speed, they examined cognitive changes of participants over the 12-year span from age 56 to 68, adjusting for participants’ cognitive ability in young adulthood. Their erectile function and sexual satisfaction were measured alongside cognition, using the International Index of Erectile Function, a self-reported assessment for male sexual health. The researchers then built a statistical model to understand how the three variables changed as individuals aged.

“Research on sexual health has historically focused on quantifiable facets of sexuality like number of sexual partners or frequency of sexual activity,” said Riki Slayday, a doctoral candidate at Penn State and lead author on the study. “What we were interested in is the perception of that activity, how someone feels about their sex life, and how that influences cognitive function, because multiple people could be in the same situation physically but experience completely different levels of satisfaction.”

The study found that decreases in erectile function and sexual satisfaction were both associated with memory decline, which the researchers say points to a connection between psychological and physical health.

“When we mapped the relationship over time, we found increases or decreases in erectile function and sexual satisfaction were associated with concurrent increases or decreases in cognitive function,” Slayday said. “These associations survived adjustment for demographic and health factors, which tells us there is a clear connection between our sex lives and our cognition.”

Prior studies have found a link between microvascular changes and changes in erectile function over time. In fact, the active ingredient in Viagra (Sildenafil) was originally developed to treat cardiovascular problems, Sliwinski explained, so the connection between vascular health and erectile function is well understood. How erectile function connects to other aspects of health should be an area of focus for future research, he added.

Increasing the assessment and monitoring of erectile function as a vital sign of health may help identify those at risk of cognitive decline before their 70s, he said. The researchers note that the older adult population in the U.S. is expected to double over the next 30 years, which means twice as many people will likely enter their 60s and experience declines in erectile function and sexual satisfaction.

“We already have a pill for treating erectile dysfunction. What we don’t have is an effective treatment for memory loss,” Sliwinski said. “Instead of the conversation being about treating ED, we should see that as a leading indicator for other health problems and also focus on improving sexual satisfaction and overall well-being, not just treating the symptom.”

Other co-authors on the paper are Tyler Bell, Teresa Warren, William Kremen and Carol Franz of the University of California San Diego; and Michael Lyons, Rosemary Toomey and Richard Vandiver of Boston University.

The work was supported the National Institute on Aging at the National Institutes of Health.