“Sugar, alcohol and tobacco,” economist Adam Smith once wrote, “are commodities which are nowhere necessaries of life, which have become objects of almost universal consumption, and which are, therefore, extremely popular subjects of taxation.”

    Two and a half centuries on, most countries impose (征税) sort of tax on alcohol and tobacco. With obesity levels putting increasing pressure on public health systems, governments around the world have begun to toy with the idea of taxing sugar as well.

    Whether such taxes work is a matter of debate. A preliminary review of Mexico's taxation found a fall in purchases of taxed drinks as well as a rise in sales of untaxed and healthier drinks. By contrast, a Danish tax on foods high in fats was abandoned a year after its introduction, during claims that consumers were avoiding it by crossing the border to Germany to satisfy their desire for cheaper, fattier foods.

    The food industry has, in general, been firmly opposed to such direct government action. Nonetheless, the renewed focus on waistlines means that industry groups are under pressure to demonstrate their products are healthy as well as tasty.

    Over the past three decades, the industry has made some efforts to improve the quality of its offerings. For example, some drink manufactures have cut the amount of sugar in their beverages (饮料).

    Many of the reductions over the past 30 years have been achieved either by reducing the amount of sugar, salt or fat in a product, or by finding an alternative ingredient. More recently, however, some companies have been investing money in a more ambitious undertaking: learning how to adjust the fundamental make-up of the food they sell. For example, having salt on the outside, but none on the inside, reduces the salt content without changing the taste.

    While reformulating (再制定) recipes is one way to improve public health, it should be part of a multisided (多边的) approach. The key is to remember that there is not just one solution. To deal with obesity, a mixture of approaches, which include reformulation, taxation and adjusting portion sizes, will be needed. There is no silver bullet.

    On the third Sunday in June, Americans take time to recognize and thank a special person in the family -fathers! Father's Day celebrates the importance of fathers, young and old and the men thought of as father figures.

    The words "the child is father of the man" come from William Wordsworth's poem My Heart Leaps Up. "It means people's personalities form when they are children. They will most likely have the same qualities as an adult that they had as a child.

    Used in everyday speech, one could say, "In his case, the child was father of the man; he loved nature as a child and now works as a botanist(植物学家)".

    Let's say you want to tell a child a story about something that happened long before they were born. You could say it happened when they “were just a twinkle in their father's eyes.” This expression has a humorous and dreamy feel. Here, the word “twinkle” suggests the interest your father had in your mother.

    When a much older man is interested in a much younger woman and supports her with his money, he is called he “sugar daddy.” The money part is very important-that's the sugar.

    Sometimes fathers are not a good influence or active in the lives of the children. In that case, a person may look for a father figure, a man who is not actually the person's father but who acts like one.

    The relationship between a man and his son can be complex. But the relationship between a father and daughter is often simpler. The expression “daddy's little girl” is understood to mean that, in a father's eyes, his daughter can do no wrong.

    There is usually not a dry eye at any wedding during the traditional father-and-daughter dance, especially if they are dancing to a song like Michael Buble's “Daddy's Little Girl.”

    If someone asked you to quantify (衡量) the time you spend online, how would you answer? If you're like one-fifth of Americans, you'd likely say “almost constantly.” New research shows that 21 percent of Americans report that they're online more or less constantly.

    Andrew Perrin, a research assistant at Pew, did a survey about Internet use. During the survey, adults were asked how much they go online. 13 percent said they don't go online and 13 percent said they go online several times a week or less. Only 10 percent said they go online once a day and much larger quantities said they go online several times a day (42 percent) or “almost constantly” (21 percent).

    Interestingly, there wasn't a gender split (性别分化) when it came to near constant Internet use. Age seems to be the great divider: Only six percent of people over 65 said they were online that much. Those who reported that they were online all the time included 12 percent of 50- to 64-year-olds, 28 percent of 30- to 49-year-olds and 36 percent of 18- to 29-year-olds.

    Don't suppose that teenagers are online more than adults, however. In another survey, Pew found that while they did have a slight edge on adults in general when it came to “almost constant” Internet use, 24 percent said they were online pretty much all the time. They still fell greatly behind the 36 percent of adults between 18 and 29 years of age who were always online.

    Given that the United Nations considers unrestricted (无限制的) Internet access (接入) to be a human right, the number of Americans who report being online “almost constantly” could rise along with availability and affordability. But it remains to be seen whether being online all the time is actually something to long for, or how constant connectivity will affect American culture in the long term.

    Forcing waiters and waitresses to survive on tips from customers rather than normal wages is a pointless, crude, and unique American custom that, in the past several years, a handful of progressive restaurant owners have attempted to do away with. Danny Meyer, CEO of Union Square Hospitality Group, is about to join their ranks and has announced that he plans to gradually stop tipping at the company's 13 restaurants.

    What, exactly, is wrong with tipping? As Brian Palmer has explained, more or less it's everything. To start, leaving a waiter's pay in the hands of customers has a feeling of classism (阶级歧视). And in theory, handing restaurant customers the power to tip is at least supposed to motivate better service. This fails in practice because humans turn out to be pretty arbitrary (随意的) about their tipping behavior. Research has shown that the amount diners tip has very little to do with their level of satisfaction. All of this doesn't encourage waiters and waitresses to do anything but turn over as many tables as possible.

    Tipping is also very unfair to kitchen staff. The law allows restaurants to divide tips between front-of-the-house workers like waiters, hosts, hostesses, and bartenders (调酒师), but not cooks. This creates a system in which the people serving the food in a restaurant can earn more than the people preparing it.

    One of the most fascinating parts of Meyer's move is that, unlike some restaurant owners who have taken an anti-tipping stand, he won't simply add a standard extra charge to diners' bills. Rather, Union Square Hospitality Group means to raise menu prices enough to fully cover the cost of a meal. If Meyer manages to move away from tipping at all without hurting his profits, it would almost certainly set the stage for others to follow suit.

    Teenagers around the world can be happy with the news that the brain will ignore parents' order when they use their smart phones. A new scientific study from the University College London has shown that humans may temporarily go deaf when they're focusing on something visual (视觉的) at the same time.

    The researchers played the normal-volume sounds in the background. And 13 volunteers experienced inattentional deafness as their visual tasks became increasingly difficult. "We found that when volunteers were performing the difficult visual task, they were unable to hear sounds that they would normally hear," Maria Chait said in a statement. "The brain scans showed that people didn't filter out the sounds on purpose. They were not actually hearing them in the first place."

    The findings, published in the Journal of Neuroscience, suggest that the centre of sights and the center of sounds share limited resources. Inattentional deafness is a common everyday experience and the study explains why, according to UCL Institute of Cognitive Neuroscience Professor Nili Lavie.

    If you try to talk to someone focusing on a book, game, or television program and don't receive a response, they aren't necessarily ignoring you. They simply might not hear you at all. This could also explain why you might not hear your bus or train stop being announced if you're lost in your phone, book or newspaper. However, some loud sounds will still be able to break through.

    Some situations could become possibly dangerous when the quieter ones go unheard. As you can imagine, in the operating room, when a doctor concentrates on his work, he might not hear the equipment beeping. It also applies to drivers who center on complex directions. Fortunately, experts have given us some useful tips on preventing such situations.