By day, Robert Titterton is a lawyer. In his spare though he goes on stage beside pianist Maria Raspopova — not as a musician but as her page turner. "I'm not a trained musician, but I've learnt to read music so I can help Maria in her performance."

Mr Titterton is chairman of the Omega Ensemble but has been the group's official page turner for the past four years. His job is to sit beside the pianist and turn the pages of the score so the musician doesn't have to break the flow of sound by doing it themselves. He said he became just as nervous as those playing instruments on stage.

"A lot of skills are needed for the job. You have to make sure you don't turn two pages at once and make sure you find the repeats in the music  when you have to go back to the right spot." Mr Titterton explained.

Being a page turner requires plenty of practice. Some pieces of music can go for 40 minutes and require up to 50 page turns, including back turns for repeat passages. Silent onstage communication is key, and each pianist has their own style of "nodding" to indicate a page turn which they need to practise with their page turner.

But like all performances, there are moments when things go wrong. "I was turning the page to get ready for the next page, but the draft wind from the turn caused the spare pages to fall off the stand," Mr Titterton said, "Luckily I was able to catch them and put them back."

Most page turners are piano students or up-and-coming concert pianists, although Ms Raspopova has once asked her husband to  help her out on stage.

"My husband is the worst page turner," she laughed. "He's interested in the music, feeling every note, and I have to say: 'Turn, turn!' "Robert is the best page turner I've had in my entire life."

"What would the world be if there were no hunger?" It's a question that Professor Crystal would ask her students. They found it hard to answer, she wrote later, because imagining something that isn't part of real life—and learning how to make it real—is a rare skill. It is taught to artists and engineers, but much less often to scientists. Crystal set out to change that, and helped to create a global movement. The result一an approach known as systems thinking—is now seen as essential in meeting global challenges.

Systems thinking is crucial to achieving targets such as zero hunger and better nutrition because it requires considering the way in which food is produced, processed, delivered and consumed, and looking at how those things intersect (交叉) with human health, the environment, economics and society. According to systems thinking, changing the food system—or any other network- requires three things to happen. First, researchers need to identify all the players in that system, second, they must work out how they relate to each other, and third, they need to understand and quantify the impact of those relationships on each other and on those outside the system.

Take nutrition. In the latest UN report on global food security, the number of undernourished (营养不良) people in the world has been rising, despite great advances in nutrition science. Tracking of 150 biochemicals in food has been important in revealing the relationships between calories, sugar, fat and the occurrence of common diseases. But using machine learning and artificial intelligence, some scientists propose that human diets consist of at least 26,000 biochemicals—and that the vast majority are not known. This shows that we have some way to travel before achieving the first objective of systems t hinking - which,in this example, is to identify more constituent parts of the nutrition system.

A systems approach to creating change is also built on the assumption that everyone in the system has equal power. But as some researchers find, the food system is not an equal one. A good way to redress (修正) such power imbalance is for more universities to do what Crystal did and teach students how to think using a systems approach.

More researchers, policymakers and representatives from the food industry must learn to look beyond their direct lines of responsibility and adopt a systems approach. Crystal knew that visions alone don't produce results, but concluded that "we'll never produce results that we can't envision".

The elderly residents(居民) in care homes in London are being given hens to look after to stop them feeling lonely.

The project was dreamed up by a local charity(慈善组织) to reduce loneliness and improve elderly people's wellbeing. It is also being used to help patients suffering dementia, a serious illness of the mind. Staff in care homes have reported a reduction in the use of medicine where hens are in use.

Among those taking part in the project is 80-year-old Ruth Xavier. She said: "I used to keep hens when I was younger and had to prepare their breakfast each morning before I went to school."

"I like the project a lot. I am down there in my wheelchair in the morning letting the hens out and down there again at night to see they've gone to bed."

"It's good to have a different focus. People have been bringing their children in to see the hens and residents come and sit outside to watch them. I'm enjoying the creative activities, and it feels great to have done something useful. "

There are now 700 elderly people looking after hens in 20 care homes in the North East, and the charity has been given financial support to roll it out countrywide.

Wendy Wilson, extra care manager at 60 Pen fold Street, one of the first to embark on the project, said: "Residents really welcome the idea of the project and the creative sessions: We are looking forward to the benefits and faun the project can bring to people here."

Lynn Lewis, director of Notting Hill Pathways, said: "We are happy to be taking part in the project. It will really help connect our residents through a shared interest and creative activities."