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Sex and snogging Whether they're just thinking about it or doing it, sex takes up a lot of a teenager's time. This new, unknown territory is a cause for concern, excitement and exploration.For both boys and girls, the key to sexual drive is the sex hormone 'testosterone'. When testosterone levels reach a certain threshold, teenagers start thinking about sex. But this does not mean they start having sex. Girls are only likely to get involved in sex if their social environment encourages it - if their friends are already involved, or if their parents are permissive, for example.But in boys, high levels of testosterone seem to lead to sexual activity regardless of their social surroundings. This may be because boys grow up in an environment in which sexual behaviour is tolerated, even encouraged, so it only takes the biological trigger to start their sexual activity.Changing role modelsAttitudes towards sex in the adult world have a huge influence on teenagers. Many of the taboos about sex that operated thirty years ago have almost completely disappeared. Teenagers know that adults have sex outside marriage and they understand the sexual references being made in much of the advertising that surrounds them. Often these are connected with lust rather than the traditional values of love.So it's no surprise that they themselves are following the trend and becoming much more open about sex. As well as taking part in sex earlier, teenagers are experimenting more and are often participating in oral sex.Teenage boys carrying condomCarrying condomsSince the campaign to prevent the spread of AIDS, teenagers have become more aware of safe sex issues, but this does not mean they are responding to the messages.Most teenagers know they should use a condom, yet they still find it excruciatingly embarrassing to buy them. There is a reluctance to carry condoms because of the implication that they are expecting to have sex. Plus, in the heat of the moment, a young person may well lack the confidence to interrupt proceedings and ask for a condom to be used.The difficulty parents and children feel when discussing sex is part of the problem. Studies have shown that teenagers get the vast majority of their information about sex from their friends. This is likely to be less accurate than information from their mum and dad.Boys produce up to 120 million sperm a day. Find out more about erections. http://www.bbc.co.uk/science/humanbody/mind/articles/emotions/teenagers/sex.shtml
Three Stages Of Love Stage 1: LUSTLust is driven by the sex hormones testosterone and oestrogen. Testosterone is not confined only to men. It has also been shown to play a major role in the sex drive of women. These hormones as Helen Fisher says "get you out looking for anything". Stage 2: ATTRACTIONThis is the truly love-struck phase. When people fall in love they can think of nothing else. They might even lose their appetite and need less sleep, preferring to spend hours at a time daydreaming about their new lover.In the attraction stage, a group of neuro-transmitters called 'monoamines' play an important role: Dopamine - Also activated by cocaine and nicotineNorepinephrine - Otherwise known as adrenalin. Starts us sweating and gets the heart racingSerotonin - One of love's most important chemicals and one that may actually send us temporarily insane Discover which type of partner you're attracted to by taking our face perception test. Stage 3: ATTACHMENTThis is what takes over after the attraction stage, if a relationship is going to last. People couldn't possibly stay in the attraction stage forever, otherwise they'd never get any work done!Attachment is a longer lasting commitment and is the bond that keeps couples together when they go on to have children. Important in this stage are two hormones released by the nervous system, which are thought to play a role in social attachments:Oxytocin - This is released by the hypothalamus gland during child birth and also helps the breast express milk. It helps cement the strong bond between mother and child. It is also released by both sexes during orgasm and it is thought that it promotes bonding when adults are intimate. The theory goes that the more sex a couple has, the deeper their bond becomesVasopressin - Another important chemical in the long-term commitment stage. It is an important controller of the kidney and its role in long-term relationships was discovered when scientists looked at the prairie vole http://www.bbc.co.uk/science/hottopics/love/
Robot future Robot future Building bridgesA computer program developed at Brandeis University in Massachusetts has learnt how to design and build bridges, cranes and tables all by itself. It reinvented support structures such as the cantilever and the triangle without prior knowledge of them.Fraud bustingCredit card companies use a computer program called The Falcon to detect card fraud. The Falcon works by constantly updating a profile of how customers use their credit cards. It then looks for uncharacteristic patterns of credit card use in the data.Roving eyesA robotic head built by a Scottish robotics company can determine a woman’s attractiveness. It works by examining faces to determine how 'feminine' or 'masculine' they are. It doesn’t work in reverse because men’s appeal is supposedly not based as much on looks. Perhaps jokingly, researchers say it could be put to use as an artificial receptionist. Consumer gadgetsRobots designed for the consumer market and employing very basic forms of AI have become increasingly popular in recent years. Sony's Aibo robot dog behaves like a puppy when it is first activated. But it "learns" new behaviour as it spends more time with its human owner. NeCoRo cat Omron's NeCoRo robotic cat and Sanyo's robotic guard dog are other examples of this wave of consumer robots. This is likely to continue in future as consumer robots become more and more sophisticated.Air wareA software program called FACES could stop mid-air collisions between planes. It makes planes perform avoidance manoeuvres in synch. When tested in a flight simulator, the software prevented a pile-up between 35 planes sharing airspace. Brave new worldOver the coming century, breakthroughs in nanotechnology, the science of ultra-small machines constructed at the molecular level, may help us build more sophisticated machines that are more compact.We may also see breakthroughs from scientists who are experimenting with connecting biological cells to silicon circuits - a phenomenon called wetware. http://www.bbc.co.uk/science/hottopics/ai/future.shtml
Applications of AI Q. What are the applications of AI? A. Here are some. game playing You can buy machines that can play master level chess for a few hundred dollars. There is some AI in them, but they play well against people mainly through brute force computation--looking at hundreds of thousands of positions. To beat a world champion by brute force and known reliable heuristics requires being able to look at 200 million positions per second. speech recognition In the 1990s, computer speech recognition reached a practical level for limited purposes. Thus United Airlines has replaced its keyboard tree for flight information by a system using speech recognition of flight numbers and city names. It is quite convenient. On the the other hand, while it is possible to instruct some computers using speech, most users have gone back to the keyboard and the mouse as still more convenient. understanding natural language Just getting a sequence of words into a computer is not enough. Parsing sentences is not enough either. The computer has to be provided with an understanding of the domain the text is about, and this is presently possible only for very limited domains. computer vision The world is composed of three-dimensional objects, but the inputs to the human eye and computers' TV cameras are two dimensional. Some useful programs can work solely in two dimensions, but full computer vision requires partial three-dimensional information that is not just a set of two-dimensional views. At present there are only limited ways of representing three-dimensional information directly, and they are not as good as what humans evidently use. expert systems A ``knowledge engineer'' interviews experts in a certain domain and tries to embody their knowledge in a computer program for carrying out some task. How well this works depends on whether the intellectual mechanisms required for the task are within the present state of AI. When this turned out not to be so, there were many disappointing results. One of the first expert systems was MYCIN in 1974, which diagnosed bacterial infections of the blood and suggested treatments. It did better than medical students or practicing doctors, provided its limitations were observed. Namely, its ontology included bacteria, symptoms, and treatments and did not include patients, doctors, hospitals, death, recovery, and events occurring in time. Its interactions depended on a single patient being considered. Since the experts consulted by the knowledge engineers knew about patients, doctors, death, recovery, etc., it is clear that the knowledge engineers forced what the experts told them into a predetermined framework. In the present state of AI, this has to be true. The usefulness of current expert systems depends on their users having common sense. heuristic classification One of the most feasible kinds of expert system given the present knowledge of AI is to put some information in one of a fixed set of categories using several sources of information. An example is advising whether to accept a proposed credit card purchase. Information is available about the owner of the credit card, his record of payment and also about the item he is buying and about the establishment from which he is buying it (e.g., about whether there have been previous credit card frauds at this establishment). http://www-formal.stanford.edu/jmc/whatisai/node3.html
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