【推荐2】A long-standing idea of urban design is that cities encourage interactions among different economic groups and so lead to less segregation (隔离). One common way to measure this is to look at where people live and their corresponding economic position. But some argue the analysis is incomplete and needs to include how people interact when they aren’t at home.

Jure Leskovec at Stanford University in California and his colleagues have used smartphone data on 1.6 billion interactions among 9.6 million people unknown by name in more than 382 US towns and cities to show that people in large cities have less social integration, and mix less with those from different socioeconomic backgrounds, than people in small towns. Leskovec and his team first looked at where each phone, representing a person, was located at around 2 am, when they were likely to be at home sleeping. “From this, we infer their income, their socioeconomic position, and then we look during the day, as these cell phones move around, how often these cell phones cross paths,” says Leskovec.

The researchers defined crossing paths as two people being in a 50-square-metre area within a 5-minute period. They tried other definitions, changing the space and time boundaries, but it didn’t transmute the findings. They found that segregation was 67 percent higher in the 10 largest cities they looked at than in the smallest, defined as having fewer than 100,000 people.

“What is new and interesting about what they’ re doing is the use of mobile phone data,” says David Manley at the University of Bristol, the UK. “That large kind of spatial (空间的) data set means that they’re able to get the population movements in a way that we haven’t been able to do before. However, the data set isn’t detailed enough to say whether people are interacting or just being in the same space, and different data sets could be needed to get that level of detail.”

【推荐3】Lucio Arreola is going to have a surprising Father's Day this year. He finds every day is surprising now. Arreola is 50 years old, the father of three daughters and a banking manager in Puerto Rico. On April 20, doctors performed a transplant to implant inside him the heart of a dead 25 year old man whose name he may never know, but to whom he and his family will always be grateful.

Arreola was told he had a heart muscle disease 15 years ago that weakened his breathing and circulation. He went on a series of medications. while he and his wife. Elena raised three daughters. They worried about their father's health. He worried about their happiness.

"I live for them."he said. "I worried if I could do what a father really should do for his children. But I knew if they were going to grow up, they had to treat me like a normal person, not a patient."

"One day up one day down." he said. "Some days dark, some light. But what hap-pens."he says."is that when the sun is out, you really feel it. Every breath is sweet. You see the trees people. You hear your daughters laugh and it's like birds singing. You tell yourself.‘There's no time in life for anything but love.'"

Liz Laguaite, a hospital music therapist(理疗师).told the Arreola family.“Why don't you try to write a song together about what you've been through and what you've learned?"They decided to try. Lucio Arreola had worried that illness might make his daughters see him their father. as weak. But instead of frailty, they mostly saw his courage to live on and positive attitude towards life. And he says their love was his powerful heart that gave him faith. hope and courage.

Arreola says he's learned that human hearts are weak. But a family's love is lasting for a long time. The Arreola family has recorded the song they ereated while Lucio recovers. It begins with the strong beat of a father's loving heart.

【推荐2】New research finds a link between poverty and poor decision making. The findings may explain why poor people sometimes make bad choices that continue their hardship.

Earlier studies have found the poor less likely to escape poverty. But there has been little research on why the poor make decisions that make their lives harder. Until recently, Eldar Shafir, a psychologist and his team did two experiments. One took place at a shopping center in New Jersey. The other was carried out among sugar cane (甘蔗) farmers in rural India.

The New Jersey experiment involved individuals with low paying jobs and others belonged to the middle class. All the volunteers were asked what they would do if their cars needed repairing.

The volunteers were given two imaginary situations. In the first, the car repair cost $150. In the second, $1,500.

“In the first, the poor and the rich performed equally well.”

“And when the repair cost $1,500, the poor performed significantly worse.” The poor lost about 13 IQ points on average. This is about the loss experienced when a person has not slept for one night.

The scientists then wondered if the same person reacted differently when he was rich and when he was poor. Once a year when the harvest comes in, the India sugar cane farmers earn most of their money, which often does not last through the year.

“So they find themselves basically rich after the harvest when the income comes in and poor just before the harvest.”

The researchers gave them tests similar to the ones taken by the people in New Jersey. They tested the Indian farmers before the harvest and after.

And the results were much the same as with the mall shoppers.

“They performed much more slowly and made many more mistakes when they were poor than when they were rich.”

Mr. Shafir says the results support 50 years of research that shows all humans have limited mental power to deal with things in life.

“And so the insight here is that, having not enough of something in a way makes it harder to make good decisions for everything else.”

【推荐3】Imagine you’re a farmer in India with a crop of potatoes to sell. Typically, you go to a marketplace called a mandi and get the best price you can from a local middleman, who will then sell them to another middleman.

Sanjay Agarwalla learned about Indian farmers’ lack of access to buyers even when he was a student decades ago. After talking the problem over with his son Aditya, then a computer science major at Princeton University, the two decided to form an online marketplace they called the Kisan Network in late 2015.

“Anything that deals with agriculture in India is pretty large. So, if it’s a problem, the problem can affect millions of people, and the impact of the solution could be enormous,” Sanjay says. After all, some 70 percent of rural households in the country depend on agriculture as a main source of income.

Kisan Network’s app lets farmers advertise their produce and see potential buyers beyond the local mandi. Once the deal is completed online, Kisan runs the produce from the farmer direct to the buyer, each side staying put.

Kisan’s fee ranges from 5 to 15 percent of the sale, and farmers get to keep more than they would under the traditional system, where middleman after middleman raises the price of the produce before it reaches a final buyer. “Even with low-profit crops like potatoes, we have been able to offer 10 percent more than physical market rates. That’s what our entire goal is,” says Aditya. “As for higher-profit crops, the improvement goes up.”

Building products for this new set of technology consumers brings its own challenges. “All of our engineers are from urban backgrounds,” says Aditya Agarwalla. “It’s not like you’re building something you would use on your own.” To be effective, Kisan’s platform must work with inexpensive smartphones on slower networks and be able to support regional languages.

Today, farmers feel it’s better selling to someone who is at their doors. They do not have to typically travel miles to a mandi, staying overnight without a place to sleep.