Humans have launched themselves into the outer space. They've landed on the moon. They've built habitable space stations that orbit the Earth. The next giant leap for mankind is to reach another planet – specifically, Mars.

    The problem is that it's no easy task. The planet is 586 times further away from the Earth than the moon, and it'll take around 180 to 220 days to reach Mars, depending on where each planet is in its orbit. Such long periods in space have suggested many potential health problems, including hormonal changes, skin conditions, and muscle and bone deterioration (损耗).

    Here's where some furry friends come in. A wide range of animals have been in space, from fruit flies and spiders to cats, and dogs. Such experiments began as far back as the late 1940s in first tests to see if living things could withstand the extreme g-force (重力) of a rocket launch.

    Mice continue to play a very important part in space experiments, mainly because the animals make excellent test subjects. They're small, which makes them inexpensive and easy to care for. In addition, their size and short life span make it possible to do the equivalent of several human years of tests in a much shorter time. Finally, because mice are mammals, they share many common characteristics with humans in terms of genetics, biology and behavior.

    Astromice have hit the headlines recently, as a team of scientists led by Betty Nusgens, professor of biology at the University of Liege in Belgium, found that the mice suffered a 15 percent thinning of their skin after 91 days aboard the International Space Station (ISS).

    This experiment was part of a wider NASA mission (任务) called the Mice Drawer System (MDS). The Italian Space Agency developed the facility, which allows six mice to be housed, monitored, and automatically fed and watered aboard the ISS, among which three survived during the mission.

    The mice have participated in 20 separate experiments, to study such effects as osteoporosis (骨质疏松症), anemia (贫血) and heart health.

    Results for the 20 experiments are coming in gradually. But it's clear that mice continue to play an important role in the ongoing quest to conquer the final frontier.

     “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.

    Most people who fly on passenger planes in the United States do not lose their luggage. Even if the luggage is lost, usually it is only delayed. Most "lost" luggage is found in a few days. Airlines search for the owners of unclaimed(未认领的) bags for up to three months. But when the owners cannot be found or the bags are not claimed, they are sold to a store in the small city of Scottsboro, in the southern state of Alabama.

    About one-half of one percent of all luggage passing through US airports is unclaimed. Many of the missing bags, and what is in them, are sold at the Unclaimed Baggage Center. Seven thousand items arrive at the store every day. Tom Barnes, who was shopping at the store said, "I can go into any of the large shopping centers, like the international malls. I can walk through there for an hour and come out with three items. But I come into this store, and then I come out with my car full of stuff."

    Brenda Cantrell, who works at the store, said, "The Unclaimed Baggage Center is the only store in America that buys and resells unclaimed baggage from the airline industry. You would be surprised at all the jackets, eyeglasses, neck pillows, blankets, laptops, Kindles, iPads, and you know, all kinds of expensive electronics."

    The store says it once sold a container for flowers for $80 that was found to be worth $18,000. And it says a painting it sold for $25 was later found to be worth $25,000.

    The store buys the luggage from the airlines. It does not examine the things inside them before buying them. Only about half of the items in the bags are suitable for sale at the store.

    Some people say it is not fair to the owners of the lost passage to sell their goods. Customer Daniel Martin is not one of them, saying, "I feel the airport may try to find the people that lose the things. If they've tried and they can't get a hold of them, it's better than throwing them away or just letting them rot in a warehouse somewhere."

    Model Railroading

    Would you like to know a fun way to learn about math? Well, you can do that with model railroading. Yes, it's true. You can learn about many school topics without using a school book. Besides that, there are many other benefits that model railroading brings us as well. In this article, we will discuss just a few of those benefits of model railroading.

    Patience and problem solving skills

    When you build a model railroad, you have to plan your railroad out. You have to decide where the tracks (轨道) will go, where to put buildings, where to put streets and any other things you would like to add to your model railroad. Also, you have to think about any problems you may have with the design you choose. How will you make railroad crossings? How will you design hills, mountains, and rivers? Deciding on what to do with your model railroad takes a lot of thought and patience, but it is not as difficult as you may think.

    Building skills

    With model railroading, you learn how to put together plastic models of buildings. Also, you can learn how to build a table for your design, or make scenery for the geography of your design. Your model railroad runs on electricity, so you learn about electronics as well. These are skills that not only help you build a model railroad; these skills will help you throughout life.

    Fun for family and friends

    Different from many video games, model railroading is a social hobby that lets you communicate with family and friends. This is because you have to communicate with family and friends as you build and run your model railroad. By spending time with the people in your life you love and care about, you learn to become closer and care more for each other. This is one of the best parts of model railroading as a hobby. Of course, the best part about model railroading is running the trains. Watching the trains run around the track and make all the sounds and do all the things that real trains do gives people hours of enjoyment. Also, there is great satisfaction in the fact that you, your family, and your friends built the model railroad.

    I hope you can learn to enjoy model railroading and experience all the benefits you just read about and many others. Happy railroading!