The sound of a mosquito can mean trouble in many parts of the world. The bite of the mosquito can be deadly. The insects carry serious diseases like malaria (疟疾). It is estimated that almost 630,000 people died from malaria and malaria­related causes in 2012, and most of these cases were in African countries.

    In the United States, a group of California scientists are working to develop a more effective and less costly substance (物质) to protect people from mosquitoes. The researchers are investigating the sense of smell in mosquitoes. They found the insects use the same receptor for identifying carbon dioxide in human breath as they do for the smell of our skin. Anandasankar Ray, who is leading the investigation, says scientists tested more than a million chemical compounds (化合物) until they found a substance called Ethyl Pyruvate. He says Ethyl Pyruvate makes the mosquitoes' receptors inactive. “When we apply Ethyl Pyruvate to a human arm and offer it to hungry mosquitoes in a cage, very few of the mosquitoes are attracted to the human arm because only a few of them are able to smell it out,” said Ray.

    Genevieve Tauxe, a member of the research team, says it was not easy to find the neurons (神经元) of noble cells that recognize both the smell of human breath and skin. “With the device used to examine the mosquito, we are able to insert a very small electrode (电极) into the part of the mosquito's nose, where its smelling neurons are and where the smell is happening,” said Tauxe.

    Anandasankar Ray says a product based on Ethyl Pyruvate may cost less to produce than DEFT, the most effective chemical treatment now in use. He says DEFT is too costly for most people who live in areas affected by malaria.

    “Perhaps by finding smells that can attack other target receptors, we will be able to improve upon DEFT and finally have the next generation of insect behaviour control products,” said Ray.

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

    Prinker: Color Your Way

    Tattoos always look so cool, but actually getting one is quite a commitment. After all, apart from using expensive laser removal therapy, they stay on your skin forever.

    The Prinker is here to change the game. It is a device (设备) that lets you create or print any image or temporary tattoos within a matter of seconds. It is connected to your smartphone and you can select a bunch of preloaded tattoos available in the app.

    This device was exhibited at The International Consumer Electronics Show in Las Vegas this year. It is manufactured by a Korean startup company called “SketchOn”.

    You can sketch your ideas out on your skin with this portable device that is almost twice the size of a computer mouse. This is a nice way to support your team in the match by printing its logo or design onto your skin. You can also share your tattoo designs with others through the app. It is also a fun and creative toy for kids to play with.

    In order to print the design, all you need to do is select or draw a design on your mobile and then press and rub the base of the device against your skin and you are done. These designs and images are water resistant but can be washed off with soap water. The ink of the Prinker is non-toxic and is made only from certified cosmetic ingredients. Each cartridge (墨盒) contains enough ink for about 1,500 tattoos, or as J₊ R. Smith would call it, “a good start.”

    The Prinker is developed by a small team of five members. The company is planning to launch the device in China and then in the United States. The device is currently commercializing in Korea as a rental device. The agencies and organizations pay $150 for a day to use it in their events or marketing.

    The current version of Prinker is aimed towards business users (think festivals, carnivals, sports events, promotion campaigns). But the company is working on a home version, and hopes to have it available to buy before the end of 2018. SketchOn estimates the personal model will retail at $200. The company is currently seeking to partner with international agencies for distribution opportunities.

    Although Prinker is currently aimed towards novelty and creative purposes, its technologies could eventually be adapted for use by professional tattoo artists or medical professionals who provide tattoos for patients, such as after a breast cancer operation or skin graft.

    A medical study has shown that excess(过度的)coffee drinking could cause heart attacks in people who do not metabolize(使新陈代谢)caffeine fast enough.

    The study, published recently in the Journal of the American Medical Association, says an enzyme(酶)that metabolizes caffeine in the liver works differently in some people, depending on the make­up of the gene(基因). People who have a slow version (版本)of the enzyme are at a greater risk(风险)of a heart attack when they drink more coffee. The risk had something to do with a person's age and how many cups of coffee he drinks.

    The team from the University of Toronto in Canada studied 4,024 people living in coffee­rich Costa Rica between 1994 and 2004, of whom half suffered non­fatal(非致命的)heart attacks. They found slightly more than half had the slow version of the gene, while the rest had the fast form.

    Two to three cups of coffee a day increased the possibilities of a heart attack by 36 percent for those with the slow­acting gene and four or more cups a day lifted it by 64 percent.

    But those under 50 who had the fast version of the gene had a lower risk of heart disease, even with four or more cups a day.

    Those with the fast­acting gene who drank two to three cups of coffee a day had 22 percent reduced possibilities of having a heart attack, but drinking four or more cups a day only lessened the risk by 1 percent. Scientists recommend limiting coffee consumption(消耗量)to within four cups a day.

    Global warming is the process of earth's atmosphere heating up. Over the last 100 years, the average temperature of earth's atmosphere has gone up 1 Fahrenheit. The weather has not changed exactly the same way in every area of the planet. But scientists think that the rise in average temperature is already affecting the earth, s climate.

    Many scientists now believe that global warming is caused by cutting down trees, producing more trash, and polluting the environment are some of the reasons that the temperature has gone up. Many scientists believe that the biggest causes of global warming are new human technologies that release greenhouse gases into the atmosphere.

    The greenhouse effect is not new. Certain gases in the atmosphere, like carbon dioxide, nitrous oxide and methane, prevent heat energy from escaping back into space. In the past, the climate didn't change much because nature produced just the right amount of greenhouse gases to deal with it.

    Today, most scientists are pretty sure that the rising temperature can't be blamed on nature. Ever since the industrial revolution in the 1700s, humans have relied on machines for daily life. And many of those machines give off a lot of greenhouse gases. An increase in the release of greenhouse gases from human activities is throwing nature off balance.

    The climate is a very complicated thing, but many scientists agree that the rising atmospheric temperature has already damaged the environment. Sheets of ice, called glaciers, are melting in Antarctica and other parts of the globe. As glaciers break off and melt into the oceans, they are adding warm water to the oceans and causing the sea level to rise.

    Over the past last 100 years, the sea level has risen 6-8 inches around the world. That means land along the coasts is beginning to disappear under water. Bigger and warmer oceans are also adding to other weather problems caused by pollution in the atmosphere. Some places have received more rain, others have had bigger storms and a few areas in the world have experienced unusual droughts.

Going to concerts and live performances is a lot of fun. As a teen, you'll want to prepare for the event far in advance in order to ensure that your concert experience is enjoyable.

Check to make sure that the concert venue(场所) is for all ages.

Some venues, particularly those that serve alcohol, will only allow entry for guests who are over 21 years old. {#blank#}1{#/blank#} If you buy a ticket and get turned away at the door, you likely will not get your money back.

Ask your parents for permission.

{#blank#}2{#/blank#} Have a conversation with your parents to figure out how you will travel to and from the concert, and talk about ground rules for staying safe at the event.

Find a friend to go with.

For your safety, it's best not to attend concerts alone. {#blank#}3{#/blank#} If you're having trouble finding company, consider posting on Facebook, Twitter, or Instagram to see if other people in your social network are interested.

Buy tickets.

If the concert is for a popular band, figure out exactly when the tickets go on sale. {#blank#}4{#/blank#}Ticketmaster. com sells tickets for bigger shows, but if you're going to a smaller show, look online at the venue's website for information on how to buy tickets.

Research venue policies and regulations.

Find the venue's web page to get a sense of what to expect, and to avoid any problem on the day of the concert. You should know how early the doors will open. {#blank#}5{#/blank#}