Donald Trump has been known to do it in the middle of the night. Kim Kardashian has done it more than 22,000 times. Many people don't understand why you would want to do it at all.

    We're talking about tweeting and, unlike posting your entire life on Facebook, this social media activity demands a particular set of skills.

    Why use Twitter? It's a way to have a one-on-one virtual connection with your heroes and anybody who interests you. Likewise, you can share your life and views with an almost limitless number of people. And it all has to be done within the limit of 140 characters of text – plus photos, videos and links – which really helps you focus your mind.

    Katy Perry has the most Twitter followers, with 95.6 million of the micro-blogging site's 317 million monthly active users. Justin Bieber isn't far behind with 91.5 million, followed by Barack Obama and Taylor Swift with around 83 million each. The heaviest hitters of Twitter are pop stars, heroes of sport and other celebrities. But you don't need to be famous to create a buzz with the right tweets at the right time.

    In fact, Katy Perry is a great example of how to do it well. She has a bubbly tweeting style that mashes up chat about her tours and her music, insights into her emotional roller coaster over the US election, and playful descriptions about her daily life. "Done with my Christmas shopping", she tweeted, and posted a link to her Instagram page that featured crazy gadgets like a "pet emergency jacket" and a "chocolate donut camera".

    To get started on Twitter, pick a simple, memorable user name like @KatyPerry, post a short profile and choose a photo. Some tips: post your own photo (not a photo of your dog, it's not Facebook) and don't be an "egg person" – referring to the absent egg-shaped image when a user hasn't posted their own picture. In that case, Twitter won't get you any followers or respect.

    Then, it's time to start tweeting by sending your updates ("what's happening?") and following people. Building up an army of followers can take time. Generally, the more people you follow and the more you tweet, the more followers you'll get. To become a Twitter star, you need to carve out a reputation for posting original, eye-catching tweets on trending topics – and maximise your visibility by mastering the use of hashtags.

    Twitter Analytics will show you how your tweets are performing and who is following you – right down to their age category, country, income bracket, gender and interests. If your popularity is flagging and your Twitter ego is keeping you awake at night, you can turn to the business of buying thousands of "followers" from online sites. But do be ware – there may be a lot of fake profiles in there and, at the end of the day, it'll feel like paying a crowd of people you don't know to come to your birthday party.

    Happy tweeting!

    You may have never heard of Lanthanum, Cerium or Neodymium, but these elements (元素) and others known as “rare earth” play a major role in modern technology. They can actually be found in many places on the earth, but not in quantities that can be mined. Only a few countries — China, America, India, Australia, Brazil and Malaysia have any that can be mined enough to be traded.

Even though some of these elements such as Cerium are as abundant as Copper, they are not found in concentrated amounts on the earth's surface. They are often mixed together with other metals, which makes extraction (提取) of these elements an expensive and an environmentally messy process. It was due to this reason that the term “rare earth” was invented.

    Rare earth metals are used widely in our life. Rechargeable car batteries, computers, iPhones, DVD players, computer monitors, televisions, lighting, lasers, glass polishing, and superconductors all use quantities of rare earth metals. Also, with the advancement in “green” technology like solar panels, these shiny materials are becoming more important than ever. An average electric car uses 10 pounds of Lanthanum for its rechargeable battery!

    America has large deposits (存储量) of rare earths and has one of the first mines. It was openedin Southern California in 1940. The element “Europium” was the first metal to be separated in quantity for use in color televisions. However, in the 1980's and 1990's, as China started producing these elements in Inner Mongolia, the mines in America and elsewhere could not keep pace. The mine in Mountain Pass, California also failed environmental regulations and shut down in 2002.

    Now, recognizing the importance of having more than one supplier of this important resource, other rare earth owning countries like India and Australia are either dusting off their rare earth mines or speeding up their production. It is believed that the debate over rare earths will become louder in the coming months and years.

    When you're having a hard time with your homework or when you're preparing for your term paper, these student-focused websites can help you with just about anything you need. The key to getting the most out of these online resources is to know how they can best be used to your advantage.

Facebook

    Although Facebook can be one of your biggest time-wasters and distractions when you are supposed to be getting work done, it can also be one of your most valuable resources. Most of your classmates will probably have a Facebook account, so anyone you need to connect with about a class you missed or about a problem is usually just a few clicks away.

SparkNotes

    With a free library of history timeline, philosophy study guides and library summaries, SparkNotes has covered just about any reading-related jam you find yourself in. Just run a search for the book, play, or short summary of the material you are supposed to read.

Amazon.com

    Do you finish every term with many expensive textbooks you will never open again? Instead of letting the money spent go to waste, get back some of your cash by selling your books on Amazon.

RateMyProfessors.com

    Choosing new classes can sometimes be like trying to pick out your clothes in the dark, a total guessing game. Which teacher gives out the hardest problem sets? How much homework will that history professor give you every week? At RateMyProfessors.com, students all over the country rate their professors on quality, helpfulness, and how hard their classes are.

 Wikipedia

    While Wikipedia isn't aimed specifically at students, it is difficult to think of another website that does more to reduce the pain of paper writing and researching. Wikipedia gives you a quick way to find sources and get the details of almost any topic you need to research — all without walking to the library.

    What's your favorite type of music? Most people may prefer rock and roll, pop or jazz. These types are most publicized by television and the radio. Country music now would seem to mistakenly belong to the category of rock or pop. Publicity of this category started to drop only after the year 2000; however, it did have its peak years just before falling down.

    What people may not know is that this type of music inspired(促成) rock and roll especially with one of the most important figures in music history-Elvis Presley-who is known as the 6/King of Rock and Roll". Elvis used to be very famous at a radio program which broadcast country music back in the late 1940- s.  Country music is influenced by jazz and blues. Rock music is also influenced by jazz and blues so that they may even seem similar.

    Nowadays, country music is closely related to pop music due to artists' preference and popular demand. Starting from the 1980's it slowly divided itself into New and Old Country Music. Legends like Johnny Cash began to slip away because the new understanding of country music actually contains pop and his music just doesn't fit the category. Fortunately, country music is still heavily promoted through websites and reviews.

    Certain types of music nowadays are linked with different age groups. Classical for the people in the mid 19th century, pop in the 1920's, and then there's country music.

    All these types continue to grow and modernize while still appealing to certain age groups. More modern country music compositions tend to become different in their own ways which makes it even harder to identify them as country music while they, again, remain appealing only to certain age groups. Active promoters of country music videos, however, seem to appeal to a large number of age groups especially those active in Australia, for as long as country music isn't mixed with other types, it will eventually regain its charm as music for all ages.

    I first met Paul Newman in 1968, when George Roy Hill, the director of Butch Cassidy and the Sundance Kid, introduced us in New York City. When the studio didn't want me for the film - it wanted somebody as well known as Paul - he stood up for me. I don't know how many people would have done that; they would have listened to their agents or the studio powers.

    The friendship that grew out of the experience of making that film and The Sting four years later had its root in the fact that although there was an age difference, we both came from a tradition of theater and live TV. We were respectful of craft(技艺)and focused on digging into the characters we were going to play. Both of us had the qualities and virtues that are typical of American actors: humorous, aggressive, and making fun of each other - but always with an underlying affection. Those were also at the core(核心)of our relationship off the screen.

    We shared the brief that if you're fortunate enough to have success, you should put something back - he with his Newman's Own food and his Hole in the Wall camps for kids who are seriously ill, and me with Sundance and the institute and the festival. Paul and I didn't see each other all that regularly, but sharing that brought us together. We supported each other financially and by showing up at events.

    I last saw him a few months ago. He'd been in and out of the hospital. He and I both knew what the deal was, and we didn't talk about it. Ours was a relationship that didn't need a lot of words.

    Some of the world's most famous musicians recently gathered in Paris and New Orleans to celebrate the first annual International Jazz Day. UNESCO(United Nations Educational, Scientific and Cultural Organization) recently set April 30 as a day to raise awareness of jazz music, its significance, and its potential as a unifying(联合) voice across cultures.

    Despite the celebrations, though, in the U. S. the jazz audience continues to shrink and grow older, and the music has failed to connect with younger generations.

    It's Jason Moran's job to help change that. As the Kennedy Center's artistic adviser for jazz, Moran hopes to widen the audience for jazz, make the music more accessible, and preserve its history and culture.

    "Jazz seems like it's not really a part of the American appetite, "Moran tells National Public Radio's reporter Neal Conan. "What I'm hoping to accomplish is that my generation and younger start to reconsider and understand that jazz is not black and white anymore. It's actually color, and it's actually digital. "

    Moran says one of the problems with jazz today is that the entertainment aspect of the music has been lost. "The music can't be presented today the way it was in 1908 or 1958. It has to continue to move, because the way the world works is not the same, "says Moran.

    Last year, Moran worked on a project that arranged Fats Waller's music for a dance party, "just to kind of put it back in the mind that Waller is dance music as much as it is concert music," says Moran. "For me, it's the recontextualization. In music, where does the emotion(情感) lie? Are we, as humans, gaining any insight(感悟) on how to talk about ourselves and how something as abstract as a Charlie Parker record gets us into a dialogue about our emotions and our thoughts? Sometimes we lose sight that the music has a wider context," says Moran, "so I want to continue those dialogues. Those are the things I want to foster. "