My parents knew their wealth: each other, their six children, and their faith. They tried to live simple lives so that they could have time for what was most important.

    They didn't busy themselves buying a bigger house, because that would mean working harder to pay the monthly mortgage(按揭贷款), working overtime or taking a second job. Who would go running with me then? Who would read stories to me?

    They didn't burden themselves with buying an expensive car because that would mean worrying about installment(分期付款) bills. Besides, walking to the shopping centre every Saturday afternoon with me gave my dad his needed exercise, and made me feel so special.

    One of my heart's delights was seeing Dad and Mom in their bedroom at night, after our nightly family prayer. The lights were turned off, and I'd see the figure of my father seated on his old chair and Mom standing behind him, gently massaging his shoulders. I'd hear them talk about what happened during their day. Even as a child, I sensed their quiet pleasure in being together.

    My question today: Could they have done this rich practice each night and nourished(滋润) their marriage if they had been busy paying for expensive clothes for themselves or their kids, or if they had been worrying about monthly bills for new hi-tech equipment? I don't think so. And I've made a choice: I don't want that of life either.

    Each time I see a balloon , my mind flies back to a memory when I was a six-year-old girl . It was a rainy Sunday and my father had recently died . I asked my mum if my dad had gone to heaven . “ Yes , honey . Of course , ” she said . “ Can we write him a letter ? ”

    She paused , the longest pause of my short life , and answered , “ Yes . ” My heart jumped . “ Can the mailman go there ? ” I asked .

    “ No , but I have an idea . ” Mum drove to a party store and returned with a red balloon . I asked her what it was for . “ Just wait , honey . You'll see . ” Mum told me to write my letter . Eagerly , I got my favorite pen , and poured out my six-year-old heart in the form of blue ink . I wrote about my day , what I learned at school , how Mum was doing , and even about what happened in a story I had read . For a few minutes it was as if Dad were still alive . I gave the letter to Mum . She read it over , and a smile crossed her face . She made a hole in the corner of the letter to tie it to the balloon . We went outside and she gave me the balloon . It was still raining . “ Okay , on the count of three , let it go . One , two , three . ” The balloon , carrying my letter , flew upwards against the rain . We watched until it was swallowed by the mass of clouds . Later I realized , like the balloon , that Dad had never let his sickness get him down . He was strong . No matter what he suffered , he'd keep on , fly up , and finally go beyond this cold world and his sick body . He rose into sky and became something beautiful . I watched until the balloon disappeared into the grey and white and I prayed that his strength was passed on . I prayed to be a balloon .

    Can exercise during childhood protect you against memory loss many decades later?Exercise early in life seems to have lifelong benefits for the brain,in rats at least.

     “This is an animal study,but it shows that physical activity at a young age is very important—not just for physical development,but for the whole lifelong track of cognitive（认知的）development during ageing,”says Martin Wojtowicz of the University of Toronto,Canada.“In humans,it may delay the appearance of Alzheimer's symptoms（阿茨海默氏症）,possibly to the point of preventing them.”

    Wojtowicz's team divided 80 young male rats into two equal groups,and placed running wheels in the cages of one group for a period of six weeks.Around four months later—when the rats had reached middle age—the team taught all the rats to connect an electric shock with being in a specific.When placed in the box,they froze with fear.

    Two weeks later,the team tested the rats in three situations: exactly the same box in the same room,the same box with the room arranged differently,and a completely different box in a different room.

    The rats without access to a running wheel when they were young now froze the same percentage of times in each of these situations,suggesting they couldn't remember which one was dangerous.But those that had been able to run in their youth froze 40 to 50 percent less in both changed box settings.

    "The results suggest the amount of physical activity when we're young,at least for rats,has influence on brain and cognitive health—in the form of better memories—when we're older,"says Arthur Kramer of Northeastern University in Boston,who has found that,in humans,exercise promotes the growth of new brain cells.

    You may think, salt is just a simple cooking element we shake on our food for a little extra taste. But salt is much more than that. Without salt our muscles would not move. Our nervous systems would not operate. Our hearts would not beat.

    But do not think rubbing salt in a wound will help. Doing that would be painful and not heal the wound. To rub salt in a wound is an idiom that means to purposefully make a bad situation worse.

    Early humans got the salt they needed to stay alive from the animals they killed. But advances in agriculture led to a diet low in salt. So, humans needed to find other sources. Those who lived near the ocean or other natural sources for salt were lucky. Those who did not had to trade for salt. In fact, people used salt as a method of payment in many parts of the ancient world. The word “salary” comes from the word “salt”.

    Salt also played an important part in population movement and world exploration. Explorers understood that if they could keep food fresh, they could travel longer distances. So they used salt to preserve food and explored the world.

    Salt was so important that, according to food historians, it was traded pound-for- pound for gold. Today, people still use the expressions “to be worth one's salt” or “worth one's weight in salt”. The expressions describe a person of value.

    A person might also be called “salt of the earth”. That description means he or she is dependable and trustworthy. However, when you say “I think we should take what he said with a grain of salt” you mean you accept it but maintain a degree of doubt about its truth.

    Mya Le Thai is a scientist studying at the University of California, Irvine. She recently discovered a process that may result in batteries that last forever. Thai said she had been discouraged that the batteries for her wireless devices degrade. Over time, they fail to charge fully.

    Thai did not like to have keep her wireless laptop connected to an electrical outlet. She decided to do something about that problem.

    At first, she and her team thought about inventing a new battery. But as they experimented, Thai discovered something that might permit lithium-ion(锂离子) batteries to last forever. Lithium-ion batteries power most wireless devices. Over time, the batteries lose the ability to hold a charge. Most of these batteries have a life span of about 7,000 charging cycles before they die.

    One of the reasons lithium-ion batteries degrade is their use of nanowires(纳米线) to carry electricity. Nanowires are extremely thin. A human hair is thousands of times thicker, for example. Nanowires are extremely efficient carriers of electricity, which makes them useful in batteries. But Thai said their thinness also makes them weak. "Nanowires break over time," she said. "That's why they lose capacity."

    But, Thai had a theory: The nanowires might last longer if covered with a material. She and the team tested her theory. The team tried many coverings for the wires. PMMA was one of them. The nanowires were coated with PMMA and cycled through charges 200,000 times. The PMMA coated nanowires showed no evidence of damage. The results suggest that batteries could last forever, without losing charging ability.

    Thai hopes to continue her research to understand why this material works so well and to see if any other material could create better results.

"It's kind of cool," she said. "I'm really glad people are showing interest in my work and not just in the work itself, but also in technology and energy."

When it comes to sitting properly, we all know the correct way even if we don't do it to the letter. No crossed legs, bottoms touching the back of the chair and feet on the ground. But even if you're doing it right, sitting for long periods is shockingly bad for you. It has been described as the new smoking, linked to heart disease and even cancer. There is no doubt we should all try to do less of it. But perhaps we could also do it better.

A classic survey, published in 1953, described 100 different sitting postures adopted by 480 cultures around the world. Among the most common were sitting cross-legged, kneeling and the deep squat (深蹲), with feet flat on the ground and bottoms resting on or just above it. Even in Western cultures, these are preferred sitting positions among young children. But Westerners tend to prefer chair use from an early age, insisting children sit on seats in school.

One big problem with this desire for chairs is that they make sitting so, well, sedentary (久坐不动的). Consider the Hadza, a group of hunter-gatherer people in Tanzania. They spend around 9 hours a day sitting. However, they squat and sit on the ground in various positions, and this involves high levels of muscle activity. The supportive nature of chairs, with their high backs and armrests, removes this effort perhaps the reason that people love them.

So what's the best way to sit? Josette Bettany-SaItikov at Teesside University, UK has found that kneeling can help keep the spine in a better position as does squatting. We might also take inspiration from traditional cultures like the Hadza. "Use a variety of postures and preferably not just still postures but some which allow movement," says Bettany-Saltikov.

Bettany-Saltikov believes that we should be rethinking what it means to do a desk job. "We still need to design workplaces that enable people to be productive while being lightly active, like with under-table cycling or walking desks," she says. For now, if your job is sedentary, don't forget to stand up regularly and move around.