Great speakers are not born but made. You too can become a good orator by taking up the public speaking courses. Those who are incapable of speaking in front of the public can't come up in their life. The art of public speaking must be practiced by everybody who wants to reach great heights in their career. A lot of public speaking courses are available on the Internet. Choosing the best course that is right for you may be difficult but not impossible.

    The basic motive of public speaking courses should be to train you to become a public speaker and improve your skills of delivering a public speech. The course should first educate you with the principles of public speaking and tell you how to overcome stress and anxiety. By overcoming fear, you will be able to deliver your presentation clearly to your audience.

    A speaker can have a great influence on the audience with his body language and your public speaking course should tell you the gestures on stage that can attract the audience. Non-verbal communication also has a major role to play in delivering a speech effectively to a group. Though body language is important, the content and the natural use of words are what the audience are closely caring about. Public speaking courses should give tips in using the right words at the right time.

    Even though you have prepared well, the real success of public speaking lies in the way your speech is delivered. Public speaking courses will train you to present the contents in a lively manner impressing the audience. Your presentation should be professional and stylish. You can add humor or interactive sessions (互动环节) to your presentation to gain the audience attraction.

    Scientists from the University of East Anglia have identified four new man-made gases that are contributing to the damage to the ozone(臭氧) layer. Two of the gases are accumulating at a rate that is causing concern among researchers.

    Worries over the growing ozone hole have seen the production of chlorofluorocarbon (CFC) gases restricted since the mid 1980s. But the precise origin of these new, similar substances remains a mystery.

    Lying in the atmosphere, the ozone layer plays a critical role in blocking harmful UV rays, which cause cancers in humans and reproductive problems in animals.

    Scientists from the British Antarctic Survey were the first to discover a huge “hole” in the ozone over Antarctica in 1985. The evidence quickly pointed to CFC gases, which were invented in the 1920s, and were widely used in refrigeration. Extraordinarily, global action was rapidly agreed to deal with CFCs and the Montreal Protocol to limit these substances came into being in 1987. A total global ban on production came into force in 2010.

    Now, the newly discovered four new gases can destroy ozone and are getting into the atmosphere from as yet unidentified sources. Three of the gases are CFCs and one is a hydrochlorofluorocarbon (HCFC), which can also damage ozone.

    The research has shown that four gases were not around in the atmosphere at all until the 1960s, which suggests they are man-made. The scientists discovered the gases by analyzing polar snow pack. Air from this snow is a natural archive of what was in the atmosphere up to 100 years ago. There searchers also looked at modern air samples, collected at remote Cape Grim in Tasmania.

    They estimate that about 74,000 tonnes of these gases have been released into the atmosphere. Two of the gases are accumulating at significant rates. However, they don't know where the new gases are being released from and this should be investigated. Possible sources include chemicals for insecticide (杀虫剂)production and solvents (溶液) for cleaning electronic components. The three CFCs are being destroyed very slowly in :the atmosphere—so even if emissions (散发)were to stop immediately, they will still be around for many decades to come.

    Of the four species identified, CFC-113a seems the most worrying as there is a very small but growing emission source somewhere, maybe from agricultural insecticides. We should find it and take it out of production.

    It's common knowledge that sleep problems can be caused by things such as stress, anxiety, or even using a smartphone before bedtime. But recently, a team of researchers discovered that genes could also be a cause of sleepless nights.

    The scientists, from Rockefeller University in New York, US, found that delayed sleep phase disorder（DSPD，睡眠相位后移综合症）, a condition that affects one's sleeping patterns, is passed down via a mutated（突变的）gene. DSPD sufferers wake up later and go to bed later than the average person. To come to their conclusion, the team studied a 46-year-old woman who is only usually able to fall asleep at 2 or 3 in the morning. It was discovered that the woman's body produces the hormone that helps her sleep at night up to 7 hours later than regular sleepers. The scientists found this was caused by a mutation in one of the woman's genes, one that helps regulate the “body clock”.

    Some of the woman's family members were also found to share the same mutation—and the same sleeping problems –leading the scientists to believe that sleep troubles are passed down through the generations.

    However, having this mutation doesn't mean you automatically have sleep problems. The team also found two people who had the mutation but reported no problems with their sleep.

    But while this is an interesting discovery, it offers no help to those who can't fall asleep at night—although there are a few things you could try to help you sleep earlier.

    BBC journalist Michael Mosley produced a TV documentary in May in which he talked about his battle with insomnia（失眠）and the techniques he used. “I avoid social media for at least an hour before bed, I do mindfulness exercises, and if I wake up in the middle of the night, I read a book for an hour or so,” he wrote in an article for the Radio Times.

Hollywood's theory that machines with evil(邪恶) minds will drive armies of killer robots is just silly. The real problem relates to the possibility that artificial intelligence(AI) may become extremely good at achieving something other than what we really want. In 1960 a well-known mathematician Norbert Wiener, who founded the field of cybernetics（控制论）, put it this way: “If we use, to achieve our purposes, a mechanical agency with whose operation we cannot effectively interfere(干预), we had better be quite sure that the purpose put into the machine is the purpose which we really desire.”

A machine with a specific purpose has another quality, one that we usually associate with living things: a wish to preserve its own existence. For the machine, this quality is not in-born, nor is it something introduced by humans; it is a logical consequence of the simple fact that the machine cannot achieve its original purpose if it is dead. So if we send out a robot with the single instruction of fetching coffee, it will have a strong desire to secure success by disabling its own off switch or even killing anyone who might interfere with its task. If we are not careful, then, we could face a kind of global chess match against very determined, super intelligent machines whose objectives conflict with our own, with the real world as the chessboard.

The possibility of entering into and losing such a match should concentrate the minds of computer scientists. Some researchers argue that we can seal the machines inside a kind of firewall, using them to answer difficult questions but never allowing them to affect the real world. Unfortunately, that plan seems unlikely to work: we have yet to invent a firewall that is secure against ordinary humans, let alone super intelligent machines.

Solving the safety problem well enough to move forward in AI seems to be possible but not easy. There are probably decades in which to plan for the arrival of super intelligent machines. But the problem should not be dismissed out of hand, as it has been by some AI researchers. Some argue that humans and machines can coexist as long as they work in teams—yet that is not possible unless machines share the goals of humans. Others say we can just “switch them off” as if super intelligent machines are too stupid to think of that possibility. Still others think that super intelligent AI will never happen. On September 11, 1933, famous physicist Ernest Rutherford stated, with confidence, “Anyone who expects a source of power in the transformation of these atoms is talking moonshine.” However, on September 12, 1933, physicist Leo Szilard invented the neutron-induced(中子诱导) nuclear chain reaction.

    Reusable straw with cleaner & case

    This stainless steel straw is a good product to replace single-use straws. The straw folds into four, meaning you can carry it in your pocket. It's also easy to clean, thanks to the supplied brush. You can get it now for just $24. 99, that's 50% off.

    Aduro Homedome Smart Outlet (插座)

    This new product fits in any outlet and allows you to control the power supply through your phone. This means you can cut your energy use, from lights to heaters. The Aduro is now 60% off at just $19. 99.

    Omega AXL Inkless Pen

    Millions of ballpoints are made and thrown away each year. The Omega AXL is a green replacement—this amazing pen puts down perfect lines using a special kind of aluminium. It never runs out and your drawings will always stay clear and tidy. Worth $39. 99, the Omega pen is now discounted to $29. 99.

    Altgalley chopsticks

    Disposable chopsticks are another example of unnecessary waste. The Altgalley chopsticks are better for the planet, and they won't affect the taste of your dish. In addition, they are specially designed so they will stand upright. This makes sure that the chopsticks stay clear of restaurant-table dirt. You can get a pair now for $11. 99, saving 33 percent on the usual price.

    When international aid is given, steps must be taken to ensure（确保）that the aid reaches the people for whom it is intended. The way to achieve this may not be simple. It is very difficult for a nation to give help directly to people in another nation. The United Nations Organization （UNO） could undertake to direct the distribution of aid. Here however rises the problem of costs. Also tied with this is time. Perhaps the UNO could set up a body of devoted men and women in every country who can speedily distribute aid to victims of floods and earthquakes.

    More than the help that one nation can give to another during a disaster, it would be more effective to give other forms of help during normal times. A common proverb says, "Give me a fish and I eat for a day, teach me to fish and I eat for a lifetime." If we follow this wise saying, it would be right to teach people from less developed nations to take care of themselves. For example, a country could share its technology with another. This could be in simple areas like agriculture or in more complex areas like medical and health care or even in building satellites. Even a small country is able to help less developed nations. Sometimes what is taken for granted, like the setting up of a water purification plant or the administration of a school, could be useful for countries which are looking about to solve common problems. It does not cost much to share such simple things. Exchange students could be attached for a number of months or years and learn the required craft while on the site. They can then take their knowledge back to their homelands and if necessary come back from time to time to clear doubts or to update themselves. Such aid will be truly helpful and there is no chance of it being temporary or of it falling into the wrong hands.

    Many countries run extensive courses in all sorts of skills. It will not cost much to include deserving foreigners in these courses. Besides giving effective help to the countries concerned, there is also the build­up of friendships to consider. Giving direct help by giving materials may be effective in the short run and must continue to be given in the event of emergencies. However, in the long run what is really effective would be the sharing of knowledge.