During a recent conversation a friend of mine complained that she found missing appendages unsettling. Ever anxious to resolve such problems, I began musing about the basically poor standard of prosthetic limbs available to amputees. The NHS for example, continues to issue devices which have not progressed since the 17th century, (Hooks for God's sake!). This, clearly is ridiculous and cannot continue. I have been paying particular attention to that most crucial of appendages,* the hand. If a hand must be amputated, the resultant loss of dexterity significantly impacts on the unfortunate amputee, but much of the mobility of the hand is controlled, not by muscles in the hand itself, but by tendons attached to muscles in the forearm. The 'gripping' action is entirely controlled thus. Some of the more advanced prostheses now available are able to detect nerve impulses in the stump, and translate these into signals controlling motors in the bionic hand, but this seems overly complicated to me; why not simply attach artificial tendons to the remnants inside the forearm, and have these control the fingers and the wrist movements directly? This would restore much of the mobility of the hand, although a number of muscles, such as those controlling the thumb, would still have to be restored electronically. Since such an arrangement would require a direct interface between the interior of the wrist and the prosthesis, the latter would have to be hermetically sealed and permanently attached. in any case, to my mind, since the original hand was a permanent attachment, any replacement should be as well. This poses the problem of how to create an interface between the skin and the prosthesis. My proposed solution is simply to implant a layer of inert polymer mesh within the dermis or the subcutis, such that skin may continue to grow through it, but will be permanently anchored to it. It in turn is anchored to the prosthetic, resulting in permanent attachment (See illustration). Hopefully a polymeric material can be selected which will not provoke the dreaded Foreign Body Reaction, while the problem still remains of how best to power the small number of motors still required within the prosthesis. For the sake of permanence, one of those plutonium based radioisotope thermoelectric generators used for powering pace-makers seems like the best option.


*(Second most crucial to those of us with a Y chromosome).

With regard to my post of Monday, June 6th, 'Flying Trains', it seems that the Scots at least, are thinking along similar lines:
http://news.scotsman.com/index.cfm?id=235382006
It's nice to see that someone on this island still has some initiative.

More Trains.

The train is, in many respects a marvellous concept. It allows large numbers of freight and passengers to be carried efficiently between specific, predetermined destinations and has historically played a large part in the economic development of the settlements served by it. Traditional railways however, do have certain drawbacks- for example, the sheer expense of levelling the ground and installing miles and miles of track. In parts of Australia and Canada, a cheaper alternative has evolved- the road train. This is nothing more than a large, diesel powered truck towing a succession of trailers, but it does represent a cost effective means of transporting large amounts of freight. Problems can arise however, for example the drivers can become mesmerised by staring at the relentless miles of featureless road ahead of them, and of course the environmentalists complain incessantly about internal combustion engines. Also the trailers, having nothing to guide them, can be difficult to steer and control. These problems can be resolved however, with a little ingenuity.
I envision a modification, whereby the train is propelled by electric motors, and these are powered by a 'pick-up' in contact with a cable spooled out along the side of the road. Arranging a conventional, overhead cable or a 'third rail' would be an expensive proposition, but I don't think this is necessary. the weight of the cable, if allowed to trail, unfettered next to the road, would tend to keep it in place. Of course the 'pick-up' would tug on it, but only at one point along its entire length at any given time, and this is in any case an advantage. Sensors in the 'arm' to which the 'pick-up' is attached could measure the push or pull exerted by it on the cable, as the train drifts closer to or further from it. A fairly simple onboard computer could then use these measurements to regulate the train's distance from the cable, and thus keep it on course, freeing the driver, like his colleagues on the railways, from the need to steer.
There is one problem- a cable trailing along the ground must be insulated from it, if it is to provide useful power to the train. Conversely, to accomplish the same, the cable must be exposed to the 'pick-up'. This can best be accomplished if the top of the cable is open to the 'pick-up', while its underside is insulated. It is then necessary to ensure that the cable remains 'upright' along its whole length.
I am put in mind of 'Mr Wobbly Man', a character from Enid Blyton's 'Noddy' series. ( http://en.wikipedia.org/wiki/Noddy ). "He is a funny little man who cannot lie down because of his wobbler and always has to stand up". This is because he possessed a hemisphere in place of legs, and his weight was so distributed that his centre of mass was directly below what would equate to the mid-point of the corresponding sphere. While this can have done little for his mobility, the result is that however far he may be tilted he would always roll back to an upright position. Similarly, by weighting it along its base, our cable can be persuaded to automatically assume the correct orientation, keeping it quite literally on an even keel.
Since 'pick-ups' could be placed along the whole length, and each carriage be independently steerable in accordance with them, controlling the carriages is no longer such a problem. This system is not limited to roads either- it could be run across whatever terrain its suspension and tires could cope with. Thus it could become a cost-effective part of the transport infrastructure in any environment where a cable could be laid. Places such as the Sahara, northern Canada, central Australia, perhaps even Antarctica, or, one day, the moon.
In practice a second cable would be required to complete the circuit of course, and I couldn't say whether AC or DC supplies would be more appropriate.

Flying Trains.

Southeast England, as I have mentioned previously (29th May 2006), is terribly short of housing. This is because Britain's economy is entirely dependent on London, while the other cities are reduced to the status of backwaters. As a consequence, everyone wants to work in London, and it follows that they want to live in the London commuter belt, which is basically, Southeast England. The problem can be partially aleviated by more high-rise buildings, but however well designed these may be, there remain practical limits on how many people can be crammed comfortably into a given area. Furthermore the increased concentration of people puts a tremendous strain on the transport infrastructure. By contrast the cities of the north maintain much lower land values, and suffer a comparative economic malaise.
In short, everyone wants to work in London, because that's where the business is, and everyone wants to do business in London, as that's where all the people are- a 'catch 22' situation.
The enviable French 'TGV' rail network, has achieved a world speed record for a (non-maglev) train of 320.3 mph ( http://en.wikipedia.org/wiki/TGV_world_speed_record ), but this was for a fairly conventionally designed train, and was attained way back in 1990. One would hope that British ingenuity could surpass this figure, to create a railway capable of averaging this speed. This is a matter of slightly increasing the top speed and maximising the acceleration that the train can accomplish. The introduction of 'broad gauge' would allow large wheels and thus reduce the wear they would otherwise suffer. A simple calculation shows that a dedicated track running in a straight line between London and Manchester, for example, could then be expected to be able to run a dedicated ferry service that could take a commuter from one city to the other in 35 minutes. Such an arrangement would place Manchester inside the London commuter belt. A similar service between London and Birmingham would be even quicker. Suddenly the pressure on housing in the south will decline, in competition with more widely available accommodation in the north. for the same reason the latter will come to enjoy the affluence currently monopolised by the Home Counties, business opportunities will expand correspondingly, and so will national prosperity- more than compensating HM Government for the subsidy that would inevitably be required to keep such a service running affordably.

The Capillary Water-Wheel.

The world, we are told, is in the grip of a growing energy crisis. This of course is not accurate- there are any number of energy sources available, it just requires a little ingenuity to tap some of them. To illustrate this point, I have devised a perpetual motion machine.
Of course every moderately attentive schoolboy knows that prepetual motion machines in the strictest sense are impossible, as they violate the first law of thermodynamics- you cannot create energy. Perpetual motion by harnassing the forces of nature however, is less of a challenge; for example, James Cox famously developed a perpetual clock powered by variations in atmospheric pressure. ( http://en.wikipedia.org/wiki/Cox )
My device works on the principles of capillary action and gravity. Capillary action is really a manifestation of surface tension which allows liquids, in this case water, to climb porous materials. In this device, a length of porous material is immersed at its base, in a trough of water. The water obligingly climbs this, and from the top of it is soaked into a seperate piece of porous substance attached to the paddles of my water-wheel. When the weight of water becomes sufficient, the paddle falls, turning the wheel and bringing the next paddle into place to repeat the process. Upon falling, the orientation of the 'sponge' on the paddle changes from horizontal to upright, reducing its capacity to hold liquid. Most of the water thus drains back into the trough below, rendering the paddle light again. The result is a perpetual turning motion, as illustrated above. The total energy output from such a contraption is inadequate for many practical uses, but working out whence the energy comes is a diverting challenge.