Bridges are an indispensable part of the infrastructure of any country and have been integral to the smooth functioning of communities ever since the earliest ancestor of man walked across a fallen tree in order to cross a stream or dyke. Over that time bridge design has progressed, diversified, and varied enormously, though there are two types that really capture the imagination  for architectural ingenuity: ‘Suspension’ and ‘cable-stayed’ (or simply ‘cable’) bridges.

Suspension bridges such as the Golden Gate Bridge (opened in 1937) – which spans the Golden Gate strait in San Francisco, California – and the Millennium Bridge (opened in 2001) – a footbridge spanning the Thames between St Paul’s Cathedral and the Tate Modern in London – have become iconic symbols of their cities. Similarly, the cable-stayed Pont Di Normandie, which runs between Le Havre and Honfleur in France has become a recognised symbol which compliments its landscape superbly.
Both suspension and cable-stayed bridges utilise the tension created by tightly pulled cables to support the main bridge structure. However, there are major differences in design which can affect an architect’s choice when designing a bridge for a specific project.

Suspension Bridges

Suspension bridges generally feature two main cables which run over the length of the bridge and are suspended from its two towers. These cables, which are anchored to the ground at each end of the bridge, are utilised to suspend trusses that are placed horizontally between each cable and the bridge deck.  The main cables bear the tension created by the weight of the deck pulling on them via the trusses, which is in turn transferred to the towers.

A suspension bridge would be the preferred choice over long distances as towers can be added to support additional length. The world’s longest suspension bridge – the Japanese Akashi Kaikyō bridge, opened in 1998 – measures 1,991 metres , whilst the longest cable-stayed bridge – the Russian Russkiy Bridge –  measures  just 1,104 metres.

Cable-Stayed Bridges

A cable-stayed bridge features support cables tied directly from the top of the support tower to the bridge deck. One advantage is that these bridges do not need their cables to be anchored at each end, as each cable runs from the tower to the deck. This makes cable stayed bridges much cheaper in comparison to suspension bridges.

However, the engineering considerations are immense in respect of the fact that a precise symmetry is needed in order to maintain balance. If a design needs to account for greater length this invariably means making longer towers that can bear more tension. Computer Aided Design (CAD) can be used to simulate real working scenarios, yet often suspension bridges are seen as more practical than very tall towers in terms of building.

Flexibility

Both suspension and cable-stayed bridges have the advantage of being highly flexible, meaning they are unlikely to break under the movement of traffic or the elements. However, their flexibility means that at times they may have to be closed due to intense movement in high wind conditions. That said, in 77 years the Golden Gate Bridge has been closed a total of only 3 times and the advantages of both types of bridge make them the first choice for structures over water, where building towers or arches upwards from a sea or river bed would often be non-viable.

Overall, both types of bridges offer almost endless possibilities in terms of design and function, and the simple differences in mechanics for either means that together they can accommodate almost any kind of budget, functional idiosyncrasy, and style. There aren’t many feats of engineering quite as classic, elegantly simple, or as important as bridges, so the next time you find yourself speeding over a length of cable-supported concrete, take a moment to appreciate just how complex and diverse bridges are.

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In recent times silk threads have also been used, apart from clothing manufacture, in the biomedical industry for bandages and sutures. However the recent advances are with the use of Spider Silk which has a higher tensile strength and also more elasticity than traditional silk. Experiments taken place by Notre Dame University, the University of Wyoming and Kraig Biocraft Laboratories, Inc., have been able to genetically produce a highbred silkworm that produces a cocoon from a combination of silkworm and spider silk.

This new product not only produces a better bandage and suture for the medical industry but also can be used for artificial skin for wounds and burns cases. Due to its high tensile strength experiments are being carried out for improved air bags for safety in cars, stronger fabrics, athletic clothing and even for the production of bullet proof vests. Silk vests are currently used by Thai police using 16 layers of ordinary silk fabric as they have a huge silk industry in that country. However when large quantities of the new spider enhance fabric are available, there would not be the need for so many layers as tests have shown the spider silk vest to be twice as strong as Kevlar, the current favoured fabric.

Scientists have even genetically altered goat DNA for them to produce milk with the spider silk embedded in it. This operation will enable large quantities of the silk to be produced and we can look forwards to a greater use of this brilliant natural material, albeit ‘adjusted’ by the Human race. Many more uses will eventually be found, especially in the medical areas where reconstruction of bodies is an ever growing industry for people wishing to live longer. Already skin is being produce in large quantities that enable burn victims to lead a better and improved life.

A recent garment was put on show in London made from Golden Orb Weaver Silk and is absolutely stunning but with a price in the millions. It took the harvesters over three years to produce the quantity necessary. Amazing applications for the future these advancements hold.

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The Pentagon is backing the research as they are looking at one day when they could conduct covert operations with the soldiers being invisible through the distortion of light. Researchers at the University of Texas, last year, were able to harness a mirage effect that made objects vanish.
Masking an object entails bending light around that object and if the light doesn’t actually hit the object, then that object won’t be visible to the human eye. The university team at Cornell has managed to hide an event for 40 picoseconds viz. 40 trillionths of a second.

Where events are concerned, concealment relies on changing the speed of light. Light that’s emitted from actions, as they happen, is what allows us to see those actions happen. Usually, that light comes in a constant flow. What Cornell researchers did just for a mere iota of time, in simple terms was to tweak the ongoing flow of light so that the event could transpire without being observable.

A beam of green light is passed down a fibre optic cable passing through a lens which splits the light into two different frequencies. One frequency moves faster than the other producing a ‘time hole’ in the beam to hide the occurrence of an event from the observer. Whilst this happens, the research team fired a red laser through the beams during a very small time gap making the transmission imperceptible. There is a long way to go before the team can mask 30 seconds, let alone several minutes. According to Cornell scientists it will take a machine 18600 miles long to produce a time mask that would last a single second.

The research certainly opens up new possibilities for masking super – quick events like data transmission which could conceal covert operations on computers. However there will be a considerable amount of research to enable the concealment of military personnel, so it will be many decades before we see the invisible soldier like the alien in the ‘Predator’ movies or the invisible Aston Martin in the James Bond movie.

One day soldiers could conduct covert operations in complete secrecy which is why the Pentagon is backing the physicists to find out how to mask entire events by distorting light. The results so far are a significant step towards the development of full spatio-temporal cloaking.

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The device transmitted information to a computer and consisted of implants of tiny electrodes threaded into a structure in the brain that is crucial for the forming of new memories. This is the same in humans as in rats and two parts of the brain known as CA1 and CA3 communicates with each other with the brain learning the information and storing it. The scientists at Wake Forest led by Dr Sam A. Deadwyler were able to introduce a drug to shutdown activity in CA1. Without CA1 activated the rats could not remember which lever to press and the rule – to push the opposite lever to the one that first appeared. The implant when switched on activated CA1 and the rat’s memory returned.

The scientist found that after distracting the rats for a considerable time their new memories faded by 40%. With the activity of CA1 being amplified by the use of the implant the memories only eroded by 10%. The scientists believe that with the use of wireless technology and computer chips this system could be used for humans. However the human brain is much more diverse and complex in its neural processes, so more research is needed to establish whether it is just this region that is affected.

Other technical problems in humans is that the signals produced by the brain in some patients may be too weak and those with severe memory problems may not be able to improve. These obstacles are being considered and the intent is to test the procedure on primates with the objective of confirming the technology to help people suffering from strokes, dementia, Alzheimer’s and memory loss through accidents.

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Well, the farfetched concept is now almost a reality with the Polytechnic University of Catalonia in Barcelona envisioning with a research team under Maria Gregori and Ignacio Llatser. They have come up with the idea of using nanobots with whip tailed bacteria contained in them to assist with the attack upon cancer tumour cells with anti cancer drugs.  The tails enable the bacteria to travel

When a nanobot finds the cancer cells it releases anti cancer drugs and the bacteria to communicate with other nanobots to come and release their anti cancer drugs. The bacteria travel through the bloodstream and are attracted to other nanobots with nutrients stored in them. They also release a coded message that the other nanobots as to the location and the site to release their drugs too.

The coded messages in the bacteria are up to 600kilobits of DNA information stored in the bacteria’s cytoplasm. Once released and attracted to other nanobots with the nutrient the encoded DNA

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Dr Seiji Aoyagi of Kansai University in Osaka, Japan has, with his colleagues developed a needle that is serrated and barely touches the skin, just like a mosquito, so you don’t feel a thing. It is delicate and is driven by tiny motors based on lead zirconium titanate, a piezoelectric crystal that vibrates at about 15hertz to control how the needle enters the skin.

Dr Aoyagi and his engineering team created a needle just one millimetre long and 0.1 millimetres in diameter. They bonded together slices of silicon dioxide into a jagged shape made by etching. The needle’s walls are only 1.6 micrometres thick. This is unlike a normal syringe that has a larger area of metal in touch with the patient’s skin, causing interaction with person’s pain sensors and their subsequent reaction.

Professor Suman Chakraborty of the Institute of Technology in Kharagpur, an expert in micro fluidics engineering, has worked on several designs of a similar nature in the past and believes that the new design by Dr Aoyagi is a substantial improvement in technology.

Dr Aoyagi believes that this could be the beginning of production of small wireless devices with the micro needle permanently attached to the patient’s body.  With a five-millimetre-wide tank attached it could collect blood and fluids to be monitored for blood sugar levels or other chemical items for lab analysis.

Further work is being undertaken on the design to mimic additional mouth parts of the mosquito in order to reduce stimulation of the nerve fibres causing the little pain experienced in tests.

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We have seen the success of Professor Hawkins with his brilliant mind locked in his handicapped body. However, the latest technology designed and developed by Tan Le & Nam Do of Emotiv EPOC has been able to feature a high resolution headset that acquires a neuro-signal from the patient’s brain and connects to a computer with a wireless setup.

The headset tunes the electrical signals from the brain thoughts, expressions and feelings and using the specialised programs the computer is able to interpret facial expressions and monitor the emotional state of the patient in real time. It is also able to interpret conscious thoughts and provide communication through the use of the computer thus giving the patient the independence and enjoyment that they would otherwise be unable to achieve.

The ongoing development looks bright for those suffering and wanting freedom from their current mundane lives in the prison of their disabled body. The Emotiv Company has also developed a number of games that can be played using their headset and programs.

The EPOC Neuroheadset and software is certainly an advance upon the 1970’s technology used by Professor Hawkins, like the mobile telephones of today being more powerful than the computers used by the Apollo astronauts visiting the Moon. It is exciting for those in need and thought provoking and inspiration for others to continue with great ideas and solutions for the future.

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The piezoelectric effect occurs only in non conductive materials such as crystals and ceramics. The most well known being quartz as used in quartz clocks. Other crystals are tourmaline, topaz, Rochelle salt and cane sugar. This effect was discovered in 1880 by the Jacques and Pierre Curie brothers.

The flexible chip designed by Professor Wang has millions of tiny nanowires measuring from 1/5,000th to 1/25th the diameter of a human hair and are capable of creating energy from low frequency vibrations and movements such as the wind. An applied mechanical stress upon Wang’s flexible nanogenerator such as flexing or pressure will generate a voltage. This means that the simple act of walking, running or even heavy breathing could be sufficient to create the energy needed. Further applications could be developed to fit on or in the body to utilize the movement and sound of the patient’s heartbeat and provide power to assist the operation of the patient’s heart.

Further developments will enable the movement of blood through the body to generate sufficient energy to power items such as iPods, mobile phones and other portable electronics. The nanogenerator is cable of providing power to a liquid crystal display or a LED light and will, according to Professor Wang, will generate enough voltage provided by two AA batteries, when five nanogenerators are stacked together.

image medgadget.com

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The full video can be watched at www.abc.net.au/tv/bigideas/stories/2009/06/26/2609568.htm

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He states that the existence of aliens is a mathematical certainty in a Universe containing 100 billion galaxies, each of which contains hundreds of millions of stars.  If humans met with another intelligent species then it could be extremely dangerous for the human race.

We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet. I imagine they might exist in massive ships, having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they can reach.

To highlight the risks, he stated that;

If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn out very well for the Native Americans.

Hawking has long held the belief that life exists elsewhere in the Universe, but in recent years his theories has been substantiated by the discovery of more than 450 planets orbiting distant stars, proving that planets are a common phenomenon.

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