I first came across the concept of pay-what-you-can cafes last summer in Boone, N.C., where I ate at F.A.R.M (Feed All Regardless of Means) Café. You can volunteer to earn your meal, pay the suggested price($10) or less, or you can overpay—paying it forward for a future customer's meal. My only regret after eating there was not having a chance to give my time. So as soon as Healthy World Café opened in York in April, I signed up for a volunteer shift(轮班).

    F.A.R.M and Healthy World are part of a growing trend of community cafés. In 2003, Denise Cerreta opened the first in Salt Lake City. Cerreta now runs the One World Everybody Eats Foundation, helping others copy her pay-what-you can model.

    “I think the community café is truly a hand up, not a handout,” Cerreta said. She acknowledged that soup kitchens(施粥所) have a place in society, but people typically don't feel good about going there.

    “One of the values of the community café is that we have another approach,” she said. “Everyone eats here, no one needs to know whether you volunteered, overpaid or underpaid.”

    The successful cafés not only address hunger and food insecurity but also become necessary parts of their neighborhood – whether it's a place to learn skills or hear live music. Some teach cooking to seniors; some offer free used books. Eating or working there is a reminder that we are all in this world together.

    My 10 am—1pm shift at World-Healthy-Café began with the café manager — one of the two paid staff members. Our volunteer crew wasn't the most orderly, but we managed to prepare and serve meals with a lot of laughs in between. At the end of my shift, I ordered my earned meal at the counter, together with other volunteers. After lunch, I walked out the door, with a handful of new friends, music in my head and a satisfied belly and heart.

    A schoolgirl saved her father's life by kicking him in the chest after he suffered a serious allergic (过敏的) reaction which stopped his heart.

    Izzy, nine, restarted father Colm's heart by stamping (踩) on his chest after he fell down at home and stopped breathing.

    Izzy's mother, Debbie, immediately called 999 but Izzy knew doctors would never arrive in time to save her father, so decided to use CPR.

    However, she quickly discovered her arms weren't strong enough, so she stamped on her father's chest .

    Debbie then took over with some more conventional chest compressions (按压) until the ambulance arrived .

    Izzy, who has been given a bravery award by her school, said: "I just kicked him really hard. My mum taught me CPR but I knew I wasn't strong enough to use hands. I was quite scared. The doctor said I might as well be a doctor or a nurse. My mum said that Dad was going to hospital with a big footprint on his chest.

    "She's a little star," said Debbie, "I was really upset but Izzy just took over. I just can't believe what she did. I really think all children should be taught first aid. Izzy did CPR then the doctor turned up. Colm had to have more treatment on the way to the hospital and we've got to see an expert."

    Truck driver Colm, 35, suffered a mystery allergic reaction on Saturday and was taken to hospital, but was sent home only for it to happen again the next day. The second attack was so serious that his airway swelled, preventing him from breathing, his blood pressure dropped suddenly, and his heart stopped for a moment.

    He has now made a full recovery from his suffering.

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    A team of engineers at Harvard University has been inspired by Nature to create the first robotic fly. The mechanical fly has become a platform for a series of new high-tech integrated systems. Designed to do what a fly does naturally, the tiny machine is the size of a fat housefly. Its mini wings allow it to stay in the air and perform controlled flight tasks.

     “It's extremely important for us to think about this as a whole system and not just the sum of a bunch of individual components (元件),” said Robert Wood, the Harvard engineering professor who has been working on the robotic fly project for over a decade. A few years ago, his team got the go-ahead to start piecing together the components. “The added difficulty with a project like this is that actually none of those components are off the shelf and so we have to develop them all on our own,” he said.

    They engineered a series of systems to start and drive the robotic fly. “The seemingly simple system which just moves the wings has a number of interdependencies on the individual components, each of which individually has to perform well, but then has to be matched well to everything it's connected to,” said Wood. The flight device was built into a set of power, computation, sensing and control systems. Wood says the success of the project proves that the flying robot with these tiny components can be built and manufactured.

    While this first robotic flyer is linked to a small, off-board power source, the goal is eventually to equip it with a built-in power source, so that it might someday perform data-gathering work at rescue sites, in farmers' fields or on the battlefield. “Basically it should be able to take off, land and fly around,” he said.

    Wood says the design offers a new way to study flight mechanics and control at insect-scale. Yet, the power, sensing and computation technologies on board could have much broader applications. “You can start thinking about using them to answer open scientific questions, you know, to study biology in ways that would be difficult with the animals, but using these robots instead,” he said. “So there are a lot of technologies and open interesting scientific questions that are really what drives us on a day to day basis.”

    Shopping for and choosing clothes is challenging enough. But imagine if you were unable to use your arms to do anything, or used a wheelchair.

    The conditions are reality for four people who became the "customers" of 15 students at Parsons School of Design at the New School this year. The students spent their spring term creating clothing to fit their customers' unique requirements as part of a class run by Open Style Lab, a nonprofit organization whose aim is to design functional and fashionable clothing for people with disabilities.

    "Disability overlaps (关联、一致) with aging and universal design," said Grace Jun, the director of the program. "We need to see it as part of our life cycle. It's something that we need to not only see from a human rights standpoint but also for its economic value."

    "I'm always looking at me being the problem and the clothing as being OK," said Kieran Kern, who gets around in a wheelchair. When Ms. Kern approached Open Style Lab, she was looking for a coat that would be easy to put on with the limitations of a weaker body. Her team came up with a design with a circular rod (杆) that runs through the collar and allows Ms. Kern to swing the coat across her back with one hand.

    "The idea of having a coat that sees the parts that make me as just parts and not as a problem that I need to solve was really liberating in an identity sense," Ms. Kern said. "Because generally, when you have a different body, you don't really see yourself."

    "I think the challenges the students faced throughout the course had a lot to do with the exchange of ideas," Ms. Jun said. "They were able to understand that no two people with a disability are alike. Being able to design uniquely means you have to have a collaborative (合作) process. We're designing with each other, not for."

    Qing-Feng Steamed Dumpling Shop. Daniang Dumpling. McDonald's. What do these companies have in common?

    Well, besides all being fast food chains, their logos are all red. And it's not a coincidence. Color is one of the many that companies use to connect with customers. And if fast food wasn't hard enough, those red logos might make it even harder to ignore.

    The average human can see ten million colors, but red is special. It's one of the first colors our ancient ancestors thought important enough to name. Early human languages were uncolorful. There were words for “black” and “white” and “red” but not much else.

    As a result, we have a deeper connection to red than any other color and we react to it in certain ways that actually play to fast food companies' advantage. For starters, researchers have found that red can cause a sense of urgency. On top of that, it also has an ability to whet (刺激) our appetites. And when you pair those two together, you've got the perfect recipe to attract hungry customers who want food, fast.

    So the red logo isn't just a welcoming sign. It's a seduction (诱惑) for your brain. Now, it's unclear why red makes us feel this way. But perhaps it has something to do with where the word comes from. Many ancient languages first named red from their word for “blood”. But red's bloody beginning has transformed. During medieval times, for example, red was worn by royals as a status symbol. And today, brides in many parts of India are married in red dress.

    In fact, red is one of the few colors today that cultures all over the world view positively. And it's no wonder companies attach so much importance to their logos. After all, we're a visual species. Despite having five senses, 80% of the information our brains process on a daily basis comes from our eyes. And according to marketing company WebPageFX, nearly 85% of consumers say the main reason they choose one product over the other is color.

    Just think what McDonald's would look like in blue, green, or pink! It's just not the same, right?

    As the temperature rises, sweaty humans are making a response that is further worsening the problem of climate change. At present, the world just has 1.6 billion air conditioning units, but these units use a surprising total of ten percent of all global electricity supply. While less than a third of families globally are so equipped, the most AC-addicted countries are Japan (in 91 percent of families), the US (90 percent) and South Korea(86 percent).

    New research by the International Energy Agency (IEA) guesses that the total number of AC units is likely to increase to over 5.6 billion by 2050－equal to ten new units being sold every second for more than 30 years－with sales driven particularly by India, China and Indonesia. This will make the use of air conditioning one of the world's largest demands for energy.

    "Growing electricity demand for air conditioning is one of the most critical blind spots in today's energy debate," argues Faith Birol, executive director of the IEA. "With rising incomes, air conditioner ownership will skyrocket, especially in the developing world. While this will improve daily lives, it is quite necessary that efficiency performance be prioritized."

    Birol and the IEA stress the need for new efficiency standards to ensure that consumers are at least buying units that require significantly less power to function, therefore decreasing the total energy demand. Variations on the traditional "vapor compression" technology, which has formed the basis for AC units for more than a century, may appear really important. A water-based system was recently developed by researchers at the National University of Singapore (NUS), which uses 40 percent less electricity and produces only one by-product: drinkable water.

    "Our cooling system can be tailored for all types of weather conditions, from wet climate in the tropics to dry climate in the deserts," says associate professor Ernest Chua at NUS. "While it can be used for indoor living and commercial spaces, it can also be easily used to provide air conditioning for blocks of buildings in an energy-efficient manner."