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One of the key challenges in urban architecture over the next 50 years will be figuring out how to squeeze vast numbers of additional people into urban areas that are already extremely 01. London, for example, will 02 have to deal with a projected 100, 000 extra inhabitants every year until 2016. The 03 plan of building new “satellite towns” of the city causes a lot of problems -- but architecture 04 tanks are working on ambitious solutions that go vertical instead of horizontal in search of 05.In 06 of population density, London is one of the 07 crowded major cities in the world — four times fewer people per square kilometer than Paris, for example, six times fewer than New York and eight times fewer than Cairo. But the fact remains that the city's population is 08 at a rapid rate, and horizontal expansion into the surrounding areas is 09 up increasingly important agricultural land, as well as worsening all the transport problems that come with urban 10.Popular Architecture would propose a radically 11 solution. The proposal is to go upwards, with vertical towers of considerable size, each representing an entire new town by the time it's 12. Each tower would be 1500 meters high. 13 mere accommodation, each tower would function as an entire town unit, with its own schools, hospitals, parks and gardens, sports facilities, business areas and community spaces. The population density of such a tower could help 14 the individual energy requirements of each inhabitant, reducing the ecological impact of the population as a whole.The village towers are considered as hollow tubes, with large holes to allow 15 and air through the entire construction. Occasional floor discs spread 16 the height of the building will give inhabitants large central areas in the middle of the tube to use as 17 spaces.While the building itself is 18 ever to be seriously considered for construction -- imagine the number of elevators it would need, let 19 the safety implications of open areas at such heights and with such wind exposure — the concept can serve as a conversation-starter for urban planners looking to 20 the challenges of the current and coming centuries.

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Passwords are everywhere in computer security. 01 too often, they are also ineffective. A good password has to be both easy to remember and hard to guess, but 02 practice people seem to pay attention to the former. Names of wives, husbands and children are 03. “123456" or “12345" are also common choices.That predictability lets security researchers ( and hackers ) create dictionaries which 04 common passwords, useful to those seeking to break in. But 05 researchers know that passwords are insecure, working out just how insecure has been difficult. Many studies have only small 06 to work on.However, with the co-operation of Yahoo!, Joseph Bonneau of Cambridge University 07 the biggest sample to date - 70 million passwords that came with useful data about their owners.Mr. Bonneau found some interesting variations. Older users had 08 passwords than young ones. People whose preferred language was Korean or German chose the most secure passwords; those 09 spoke Indonesian the least. Passwords 10 to hide sensitive information such as credit-card numbers were only slightly more secure than those protecting less important things, like 11 to games. “Nag screens” that told users they had chosen a weak password made virtually no 12. And users whose accounts had been hacked in the past did not make more secure choices than those 13 had never been hacked.But it is the broader analysis of the sample that is 14 most interest to security researchers. For, despite their differences, the 70 million users were still predictable 15 that a generic password dictionary was effective against 16 the entire sample and any slice of it. Mr. Bonneau is blunt: “An attacker who can manage ten guesses per account will compromise around l % of accounts." And that is a worthwhile 17 for a hacker.One obvious solution would be for sites to limit the number of guesses that can be 18 before access is blocked. Yet whereas the biggest sites, such as Google and Microsoft, 19 take such measures, many do not. The reasons of 20 not doing so are various. So it's time for users to consider the alternatives to traditional passwords.

John Lubbock, a British member of the Parliament, led to the first law to safeguard Britain's heritage — the Ancient Monuments Bill. How did it 01?By the 02 1800s more and more people were visiting Stonehenge for a day 03. Now a World Heritage Site owned by the Crown, it was, at the time, privately owned and neglected.But the visitors left 04 rubbish and leftover food. It encouraged rats that made holes at the stones’ foundations, 05 them. One of the upright stones had already fallen 06 and one had broken in two. They also chipped pieces off the stones 07 souvenirs and carved pictures into them, says architectural critic Jonathan Glancey.It was the same for 08 pre-historic remains, which were disappearing fast. Threats also included farmers and landowners as the ancient stones got 09 the way of working on the fields and were a free source of building materials.Shocked and angry, Lubbock took up the 10. When he heard Britain's largest ancient stone circle at Avebury in Wiltshire was 11 for sale in 1871 he persuaded its owners to sell it to him and the stone circle was saved.“Lubbock 12 national attention for ancient monuments," says Glancey. “At the time places like Stonehenge were just 13 as a collection of stones, ancient sites to get building materials.”“Lubbock knew they were the roots of British identity. He did for heritage 14 Darwin did for natural history."But Lubbock couldn't 15 every threatened site. He knew laws were needed and tabled the Ancient Monuments Bill. It 16 government powers to take any pre-historic site under threat away from uncaring owners, a radical idea at the time.For eight years he tried and failed to get the bill through parliament. Finally, in 1882, it was 17 into law. It had, however, been 18 down; people had to willingly give their ancient monuments to the government. But what it did do was plant the idea that the state could preserve Britain's heritage 19 than private owners.Pressure started to be 20 on the owners of sites like Stonehenge to take better care of them.

Late last year, I needed to transport some furniture from our house in Sussex to my son's flat in central London. I 01 a man to do it for me, but foolishly confident in my driving ability, l decided to hire a van and drive it 02. It was a Ford Transit 280, long and wide; you couldn't see out of the back. You never really knew how close you were to anything 03 on the road.Reversing in my home yard, l crashed into a small shed, causing permanent 04. At least l owned the shed.l loaded up the furniture and set 05. By now it was rush 06. My nerves broke down, as I steered the huge van through ever-shifting lanes, across oncoming vehicles, between distances of buses, at last to Charlotte Street.Here, I found an 07 parking space. As I reversed into it, I noticed three people at a pavement café 08 to me. l got out, trembling violently, like one 09 has just endured a stormy Atlantic crossing. “You've shifted the car parked 10 you three feet," they said, and it belonged 11 a disabled person. I examined the car. There were white scratches 12 its front bumper. It bore a disabled 13. So, now I was a bad driver and a bad man. Under the stern gaze of the three, I left an apologetic note on the damaged car's windscreen, 14 my phone number.l 15 the furniture, dripping with sweat. Wanting only to escape the monster, I drove the van back to its base on the Edgware Road. On arrival, the hire man told me I must 16 it up with petrol before returning it. “Just charge me," I cried, still shaking with 17. He gazed at me with understanding. No doubt he'd witnessed 18 in this state before. "How 19 I drive you to a petrol station, you fill up, and l drive her back?” he asked.He danced the great van through the traffic so casually that it 20 me if I had not been so grateful.

By the time you retire, there's no doubt about it, your brain isn't what it used to be. By 65, 01 people will start to notice the signs: you forget people's names and the teapot occasionally turns 02 in the fridge.There is a good reason 03 our memories start to let us down. At this stage of life, we are steadily losing brain cells in critical areas. This is not too 04 of a problem at first; even in old age, the brain is flexible 05 to compensate. At some point, though, the losses start to make 06 felt.Clearly, not everyone ages in the same way, so what's the difference 07 a happy, intelligent old person and a forgetful, bad-tempered granny? And can we improve our chances of becoming the 08?Exercise can certainly help. Numerous studies have shown that gentle exercise three 09 a week can improve concentration and abstract reasoning in older people, perhaps 10 encouraging the growth of new brain cells. Exercise also helps 11 our blood sugar. As we age, our blood sugar control 12, which causes a large increase in blood sugar levels. This can affect an area that helps form memories. Since physical activity helps control blood sugar, getting out and about could reduce these 13 and, potentially, improve your memory.Coordination training could also help. Studies have shown 14 specifically targeting motor control and balance improves learning function in 60 to 80-year-olds.“Brain training" was once considered strange, 15 a study concludes that computerised brain exercises can improve memory and attention in the over 65s. 16, these changes were large enough that participants reported significant improvements in everyday activities, such 17 remembering names or following conversations in noisy restaurants.Avoiding the complaints is even easier. 18 fact, your brain is doing all it can to ensure a contented retirement. By 65, we are 19 better at increasing the experience of positive emotion, says Florin Dolcos, a neurobiologist at the University of Alberta in Canada. In experiments, he found that people over the age of 60 tended to remember 20 emotionally negative photographs compared with positive ones than younger people.