Visiting Joshua Tree National Park, California

    Joshua Tree National Park is nearly 800,000 acres (英亩) large and surrounds parts of the Mojave and Colorado Deserts in South-central California. Although deserted at first sight, the park is full of wildlife and provides a variety of entertainment activities from hiking to climbing. Within a three-hour drive, Joshua Tree National Park takes at least a full day to visit.

Things to do

    Hiking opportunities within the park include several choices, from 12 self-guided nature routines to all-day back-country hikes.

    Joshua Tree NP has nine camping grounds, and back-country camping is also allowed.

    Rock climbing is a popular activity in the park, which has 10 mountains greater than 5, 000 feet in height.

When to visit

    Joshua Tree NP is open 365 days a year, although the best time to visit is October through April, when temperature is milder. The peak season is when the wild flowers bloom, and the summer months are the least crowded.

What to bring

    In addition to your camera and telescope, be sure to carry lots of water. Park and guiding maps can be picked up at any of the three visitor centers.

Fees

    Parking fees: You can buy a seven-day vehicle permit (周票) for $ 15, a single entry permit for $ 5, or Joshua Tree National Park annual (每年的) pass for $ 60.

    Camping fees: They vary by camping ground

    Are you interested in students in other countries: Do they also have so much homework like you? What do they do in their spare time?

    On April 8,a report came out on the lives of high school students in China,Japan,South Korea and the US.It surveyed（调查）around 6,200 students from the four countries last year.You will find the answers to many of your questions in this report.

    Who study hardest?

    Chinese students spend the most time studying.Nearly half of Chinese students(48.6%) spend more than two hours on their homework every day.That's much more than students of the US(26.4%),Japan(8.2%) and South Korea (5.2%).

    Who sleep most often in class?

    Japanese students fall asleep in class most often.About 45% of them said they sometimes sleep in class.In South Korea, it's 32%;in the US,21%;and 5% in China.

    Who are the most distracted（分心的）?

American students are the most active in class,but also the most distracted.64.2% said they chat with friends in class;46.9% said they eat snacks in class;and 38.9% said they send emails or read storybooks in class.

    What do they do after school?

    In their spare time, most Chinese students study or surf the Internet.Most American students go out to play with their friends.Most Japanese students do physical exercises.Most Korean students watch TV.

    Blind people usually possess one advantage over other people who can see. Their sense of hearing is far more acute. Bats, whose sight is poor, use a sound location system to help them avoid blocks in the dark. They send out pulses of sound waves, pitched at 50,000 cycles per second, far above the limits of the human ear, which can hear sounds up to frequencies of about 20,000 cycles per second. As the echoes bounce back off obstacles such as trees and walls, the bats are able to take proper action.

    The first steps to help blind people to see with sound are based on exactly the same principle. The sound is given off by an ultrasonic (超声的) torch, whose shape is different from a normal electric torch. It is double-barreled. It works in a similar way to a sonar (声呐) unit on a warship or submarine. The unit's transmitter sends out pulses of ultrasonic waves at the same frequency as the bat and the receiver picks up the returning echoes. Because these are still above the frequency at which the human ear can pick them up. The echoes are filtered (过滤) through circuits that turn them into “bleeps” which can be clearly heard before passing them into headphones.

    This means that a person holding the torch can point it ahead of him and scan the area for obstacles over a range of about 25 feet. If there are no return echoes coming through the headphones, then there is nothing in the way. If echoes do come back, then the closer the obstruction the faster the succession of bleeps and the deeper the pitch of each bleep. With practice, the torch could help a blind person to lead a more normal life.

    At present, the experimental ultrasonic torch requires a shoulder bag to carry the batteries, cables for the power supplies and earphones, as well as the torch itself. Fortunately, reducing the size of the electronic equipment is progressing and it should not be long before the whole set-up can be reproduced in a form small enough to fit into a pair of glasses. The wearer would face in the direction he wanted to check, and lift or lower his head just as a sighted person would.

    People typically wash their hands seven times a day in the United States, but they do it at a far higher temperature than is necessary to kill germs, a new study says. The energy waste is equivalent to the fuel use of a small country. Amanda R. Carrico, a research assistant professor at the Vanderbilt Institute for Energy and Environment in Tennessee, told National Geographic that hand washing is often “a case where people act in ways that they think are in their best interest, but they in fact have inaccurate beliefs or outdated perceptions.”

    Carrico said, “It's certainly true that heat kills bacteria, but if you were going to use hot water to kill them it would have to be a way too hot for you to tolerate.”

Carrico said that after a review of the scientific literature, her team found “no evidence that using hot water that a person could stand would have any benefit in killing bacteria.” Even water as cold as 40°F (4.4℃) appeared to reduce bacteria as well as hotter water, if hands were scrubbed, rinsed(冲洗)and dried properly.

    Using hot water to wash hands is therefore unnecessary, as well as wasteful, Carrico said, particularly when it comes to the environment. According to her research, people use warm or hot water 64 percent of the time when they wash their hands. Using that number, Carrico's team calculated a significant impact on the planet.

    “Although the choice of water temperature during a single hand wash may appear unimportant, when multiplied by the nearly 800 billion hand washes performed by Americans each year, this practice results in more than 6 million metric tons of CO2 equivalent emissions annually,” she said.

    The researchers published their results in the July 2013 issue of International Journal of Consumer Studies. They recommended washing with water that is at a “comfortable” temperature, which they noted may be warmer in cold months and cooler in hot ones.

    Every year, millions of people head to London's Trafalgar Square to see Nelson's Column, and the four lion statues that “guard” it. And last month, during the London Design Festival, a bright red lion sculpture was added to the collection.

    But this was more than just a statue: It had a large open mouth, with an LED screen inside it. At the same time, passersby could type in random words on a screen close to the lion, which were used to produce an AI-created poem. The most interesting part of the poems lies in their randomness, as the words that people choose to enter include many things, such as the time, the weather and their mood. In the daytime, the finished poem appeared on the LED screen, but at night, it was projected (投射) onto the lion's body and the famous Nelson's Column, in a 1ovely light display.

    Es Devlin, the sculpture's creator, was inspired by the history behind the four historic lion statues. Edwin Landseer, the designer of the lions, wanted them to look much more animated, but Queen Victoria refused his plan. This made Devlin wonder, "What if we could give a lion a poetic voice?" According to Devlin, although England has seen many poems about national identity in recent years, these works have been lacking imagination. "I wanted to make a piece that was poetic and collective" he told BBC News.

    After standing for almost 180 years, the purpose of Trafalgar Square has changed over the years. But thanks to the high-tech lion and its poetry, the square is standing the test of time.

    In the early decades of the United States, the agrarian(土地的) movement promoted the farmer as society's hero. In the minds of agrarian thinkers and writers, the farmer was a person on whose well-being the health of the new country depended. The period between the Revolution, which ended in 1783, and the Civil War, which ended in 1865, was the age of the farmer in the United States. Agrarian philosophers, represented most eloquently by Thomas Jefferson, celebrated farmers extravagantly for their supposed centrality in a good society, their political virtue, and their Superior morality. And virtually all policy makers, whether they subscribed to the tenets of the philosophy held by Jefferson or not, recognized agriculture as the key component of the American economy. Consequently, government at all levels worked to encourage farmers as a social group and agriculture as economic enterprise.

    Both the national and state governments developed transportation infrastructure, building canals, roads, bridges, and railroads, deepening harbors, and removing obstructions from navigable streams. The national government imported plant and animal varieties and launched exploring expeditions into prospective farmlands in the West. In addition, government trade policies facilitated the exporting of agricultural products.

    For their part, farmers seemed to meet the social expectations agrarian philosophers had for them, as their broader horizons and greater self-respect, both products of the Revolution, were reflected to some degree in their behavior. Farmers seemed to become more scientific, joining agricultural societies and reading the farm newspapers that sprang up throughout the country. They began using improved implements, tried new crops and pure animal breeds, and became more receptive to modern theories of soil improvement.

    They also responded to inducements by national and state governments. Farmers streamed to the West, filling frontier lands with stunning rapidity. But farmers responded less to the expectations of agrarians and government inducements than to growing market opportunities. European demand for food from the United States seemed insatiable. War, industrialization, and urbanization all kept demand high in Europe. United States cities and industries grew as well; even industries not directly related to farming thrived because of the market, money, and labor that agriculture provided.