By the mid-nineteenth century, the term “icebox” had entered the American language, but ice was still only beginning to affect the diet of ordinary citizens in the United States. The ice trade grew with the growth of cities. Ice was used in hotels, pubs, and hospitals, and by some forward-looking city dealers in fresh meat, fresh fish, and butler. After the Civil War (1861-1865), as ice was used to refrigerate freight cars(货车), it also came into household use. Even before 1880, half the ice sold in New York, Philadelphia, and Baltimore, and one-third of that sold in Boston and Chicago, went to families for their own use. This had become possible because a new household convenience, the icebox, a precursor（前身）of the modem refrigerator, had been invented.

    Making an efficient icebox was not as easy as we might now suppose. In the early nineteenth century, the knowledge of the physics of heat, which was essential to a science of refrigeration, was undeveloped. The common belief that the best icebox was one that prevented the ice from melting was of course mistaken, for it was the melting of the ice that performed the cooling. Nevertheless, early efforts to economize ice included wrapping the ice in blankets, which kept the ice from doing its job. Not until near the end of the nineteenth century did inventors achieve the delicate balance of insulation(绝缘) and circulation needed for an efficient icebox.

    But as early as 1803, an intelligent Maryland farmer, Thomas Moore, had been on the right track. He owned a farm about twenty miles outside the city of Washington, for which the village of Georgetown was the market center. When he used an icebox of his own design to transport his butter to market, he found that customers would pass up the rapidly melting butter of his competitors to pay an extra price for his butter, still fresh and hard in neat, one-pound bricks. One advantage of his icebox, Moore explained, was that fanners would no longer have to travel to market at night in order to keep their produce cool.

With the clicking of walking sticks and determined steps, a long line of walking group along the winding road is a fantastic sight. Almost each of the walkers is using some kind of fitness tracker. A few Fitbits, some Xiaomi wrist bands (手环), a couple of phone apps and some other pedometers (计步器) — and all, they say, are counting their steps.

    Fitness trackers are in. Sales figures for 2016 released by Internet Data Center (IDC) indicated 25% market growth compared to the previous year, with Fitbit taking the lion's share, followed by the brand Xiaomi.

    However, the wearables market has had a rollercoaster ride in recent months. Jawbone, once a popular fitness tracker brand, announced that it is leaving the consumer market. Microsoft has removed its Fitness Band on its online store although it is still available on retail (零售) giant Amazon. Fitbit remains a key brand name at the heart of the fitness tracker revolution. But it is recently reported to be cutting down on workers, and its founder James Park said it experienced “softer than expected” sales recently.

    Counting steps is probably the most common use of wearable devices (可穿戴设备), but recently experts have questioned whether the golden goal of walking 10,000 steps a day is actually worthwhile, and a US study concluded that health trackers did not aid weight loss.

Analyst Ben Wood from CCS Insight used to wear a fitness tracker on either wrist. Now, however, his concern is about users'experience — these devices don't tell you anything new after a while. There are also battery problems and many of the older and cheaper varieties aren't waterproof (防水的).

    When we think of a generation gap we usually think of conflicting tastes in music, or pastimes. But now the generation gap is handwriting. After one teacher in Tennessee discovered that she had students who couldn't read the assignments she was writing on the board, she posted it on the Internet saying handwriting should be taught in schools.

    Opponents claim that handwriting has become out of time in our modern world. Typed words have become a primary form of communication. Once a practical kill handwriting is no longer used by the vast majority of Americans. It is no longer taught in schools, and some claim that the time that it would take to teach it could be put to better use, for instance, by teaching the technical skills.

    But even in today's world there are still plenty of reasons to pick up a pen and apply it to paper. Many American institutions still require original signatures, for instance, signing for a registered letter and buying a house. And original signatures are much more difficult to forge(伪造) than their digital counterparts. There is also strong evidence that writing by hand is good for the mind. It activates a different part of the brain, and improves fine moving skills in young children. People also tend to remember what they write by hand more than what they type, and the process of writing by hand has been shown to stimulate ideas. Besides, studies have shown that kids who write by hand learn to read and spell earlier than those who don't. Not to mention, handwriting is pleasing, as is evidenced by the fact that no one has ever typed a love letter. And handwriting remains popular as an art form.

    Yes, we live in a modern world, but we live in a modern world that is based on fundamental values.

    A new study, which was published in the American Journal of Preventive Medicine, found that heavy use of platforms such as Facebook and Snapchat was associated with feelings of being separated from society among young adults—basically the opposite of what we are led to believe.

    Study co-author Brian Primack and his team surveyed 1,787 U. S. adults aged 19 to 32 and asked them about their usage of 11 social media platforms. They also asked participants questions related to social isolation, such as how often they felt left out. The participants who reported spending the most time on social media—over two hours a day—had twice the odds of perceived（感知到的）social isolation than those who said they spent a half-hour per day or less on the same sites.

    According to Tom Kersting, psychotherapist and author of Disconnected, the key to understanding these results lies in our understanding of “connections.” “Humans are social —emotional beings, meaning that it is in our DNA to be connected, face-to-face, with other humans,” he told Reader's Digest. “Although people think being on social media all the time makes them 'connected' to others, they are actually 'disconnected,' because the more time one spends behind a screen, the less time one spend face-to-face.”

    “Part of the issue of loneliness is that the majority of people who use social media aren't just posting, they are also viewing,” Kersting continued. “They are spending a lot of time looking at everyone else's posts, where they are and what they are doing. The constant exposure to everyone else's 'perfect' life experiences causes feelings of being left out.”

    So what's the answer? It's simple, says Kersting. “The solution to this is resisting the temptation to look at everyone else's life. Just focus on your own life, where you're going, what you are grateful for, and what you want to accomplish in this world.”

    Beyoncé Knowles can do something that many humans struggle with: sing and dance at the same time. But, it turns out this great ability is not unique to humans. The superb lyrebird, already known to be a gifted singer, can perform coordinated(协调的)song­and­dance routines(一套舞蹈动作)that put most humans to shame.

    The superb lyrebird is one of only two lyrebird species living in Australia, the other named Albert's lyrebird. Male lyrebirds have tails in the shape of an ancient musical instrument when spread out. Like most animals with beautiful body parts, the males use their tails to attract females. Each one sets up a small mound(小丘)on the forest floor, where he walks around proudly and sings. He also shows his tail by holding it over his head.

    Lyrebirds are gifted mimics(模仿者), so their songs combine their own calls, the songs of other species, and sounds they have heard in the forest. That would be enough showing off for other animals, but male superb lyrebirds also dance.

    Anastasia Dalziell of the Australian National University in Canberra filmed 12 lyrebirds in the wild. She found that males only danced during four song types, and that each song type was accompanied by a specific move. “Lyrebirds match different dance styles to different types of songs, ”she says. For example, when the male sang a series of rapid notes he also stepped to the side and held his tail wide. Another song type was accompanied by jumping and moving up and down, with the tail held narrow.

    “Our results suggest that the coordination between song and dance—like movements we see in humans can occur in other animals,” says Dalziell. Female lyrebirds might prefer males that are better at coordinating song and dance, although there is no evidence of that yet.

In a study of 33 years of trends in Body Mass Index (体重指数) across 200 countries, the scientists found that people worldwide are getting heavier {#blank#}1{#/blank#}that most of the rise is due to gains in BMI in rural areas. 

BMI is an internationally recognized measurement tool {#blank#}2{#/blank#}

gives an indication of whether someone is a healthy weight. It is calculated by dividing a {#blank#}3{#/blank#} (person) weight in kg by their height in metres squared, and a BMI of between 19 and 25{#blank#}4{#/blank#} (consider) healthy. 

The study found that between 1985 and 2017, average rural BMI increased {#blank#}5{#/blank#}2.1 in women and men. In cities, however, the gain {#blank#}6{#/blank#} (be)1.3 in women and 1.6 in men. The researchers described "striking changes" in the geography of BMI. In 1985, urban men and women in more than three quarters of the countries{#blank#}7{#/blank#} (study) had higher BMIs than men and women in rural areas. But 30 years later, the BMI difference between urban and rural people in many countries had narrowed {#blank#}8{#/blank#} (sharp). 

This may be due to some disadvantages for people {#blank#}9{#/blank#} (live) in the countryside, including {#blank#}10{#/blank#} (low) levels of income and education, higher costs of healthy foods, and fewer sports facilities.