"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".

Rome can be pricey for travelers, which is why many choose to stay in a hostel ( 旅 社 ). The hostels in Rome offer a bed in a dorm room for around

$25 a night, and for that, you'll often get to stay in a central location (位置) with security and comfort.

Yellow Hostel

If I had to make just one recommendation for where to stay in Rome, it would be Yellow Hostel. It's one of the best-rated hostels in the city, and for good reason. It's affordable, and it's got a fun atmosphere without being too noisy. As an added bonus, it's close to the main train station.

Hostel Alessandro Palace

If you love social hostels, this is the best hostel for you in Rome. Hostel Alessandro Palace is fun. Staff members hold plenty of bar events for guests like free shots, bar crawls and karaoke. There's also an area on the rooftop for hanging out with other travelers during the summer.

Youth Station Hostel

If you're looking for cleanliness and a modern hostel, look no further than Youth Station. It offers beautiful furnishings and beds. There are plenty of other benefits, too; it doesn't charge city tax; it has both air conditioning and a heater for the rooms; it also has free Wi-Fi in every room.

Hotel and Hostel Des Artistes

Hotel and Hostel Des Artistes is located just a 10-minute walk from the central city station and it's close to all of the city's main attractions. The staff is friendly and helpful, providing you with a map of the city when you arrive, and offering advice if you require some. However, you need to pay 2 euros a day for Wi-Fi.

Who is a genius? This question has greatly interested humankind for centuries.

Let's state clearly: Einstein was a genius. His face is almost the international symbol for genius. But we want to go beyond one man and explore the nature of genius itself. Why is it that some people are so much more intelligent or creative than the rest of us? And who are they?

In the sciences and arts, those praised as geniuses were most often white men, of European origin. Perhaps this is not a surprise. It's said that history is written by the victors, and those victors set the standards for admission to the genius club. When contributions were made by geniuses outside the club—women, or people of a different color or belief—they were unacknowledged and rejected by others.

A study recently published by Science found that as young as age six, girls are less likely than boys to say that members of their gender（性别）are "really, really smart." Even worse, the study found that girls act on that belief Around age six they start to avoid activities said to be for children who are "really, really smart." Can our planet afford to have any great thinkers become discouraged and give up? It doesn't take a genius to know the answer: absolutely not.

Here's the good news. In a wired world with constant global communication, we're all positioned to see flashes of genius wherever they appear. And the more we look, the more we will see that social factors（因素）like gender, race, and class do not determine the appearance of genius. As a writer says, future geniuses come from those with "intelligence, creativity, perseverance（毅力）, and simple good fortune, who are able to change the world."