The natural assassin
Because there are environmental regulations covering the use of ant powder, is there any reason why you could not tame an anteater to do the job for you, therefore providing a wholly natural solution to the problem? Would a single suburban garden be enough to sustain the anteater or would you have to hire it out to neighbours and friends?
鈥� Anteaters have developed special features for feeding from anthills in South America. However, their enormous claws, said to be able to kill a jaguar, would not be suited to breaking open the patios and house bricks that house ant colonies in the British suburbs. Their long snouts would be equally useless for poking into cracks between bricks, because they have evolved into toothless tubes for sticking inside the huge mounds made by colonial insects in their native countries 鈥� not the small holes made by pesky ants in UK gardens.
Finally, anteaters need to eat as many ants as possible while awake, because ants do not provide very nutritious fare. The average suburban garden in the UK simply would not have enough ants for an anteater to survive, even if it were shared with other households and their gardens.
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Victoria Clent
Northampton, UK
鈥� The trouble with anteaters, and other creatures that eat ants, is that they actively hunt out ants or termites rather than just catching them as they wander past. This means that once your garden became ant-free, your anteater would be looking to move on.
The Australian thorny devil is one of the few animals that relies on the ants to do the legwork, but it is a bit impractical for our climate.
Instead, I invented a very good, environmentally friendly cure while I was living in Hong Kong. First, you need to find a wandering ant in your house, garage, garden or greenhouse and then pile a teaspoon of sugar in front of it. Wait a few hours, and you will see that a clearly visible line of ants will link the spoonful of sugar with their nest.
Once you have located this point, decide where you would like the ants to stop 鈥� just outside your house or garage, rather than inside, is as good a place as any. Pile another tablespoon of sugar at this point. The ants will pick this up, turn round and return to the nest with it, and will not bother travelling any further. The column of ants to the original teaspoon of sugar will quickly peter out, and you can clear it up.
Then keep an eye on the new pile of sugar 鈥� it may need topping up occasionally if you have a large nest, but it will certainly solve your problem.
Jason Miller
Hemel Hempstead, Hertfordshire, UK
Hello, I鈥檓 on the train
How fast must a train be travelling for the Doppler effect to put all the mobile phones being used on it out of action?
鈥� The Doppler effect says that if an object emitting a wave is approaching the receiver of the wave, it is heard at a higher frequency by the following factor:
frequency heard = frequency sent 脳 (1/(1-speed/c))
where c is the speed of your wave (practically the speed of light in this case).
If the emitter is moving away from your receiver, its frequency is lowered by the following factor:
frequency heard = frequency sent 脳 (1/(1+speed/c))
In the UK, mobile phones use either the GSM900 protocol, broadcasting in the 890-915 megahertz range for uplinks and 935-960 MHz for downlinks, or the GSM1800 protocol, with equivalent ranges of 1710-1785 MHz and 1805-1880 MHz.
To ensure that one end of each of these ranges is Dopplered out the other end, one would need to travel at a speed of roughly 3 per cent of the speed of light for GSM900 signals, or 4 per cent for GSM1800. This amounts to a train speed of between 32 million and 43 million kilometres per hour.
Somehow I don鈥檛 think that鈥檚 likely on UK trains. Or indeed any others, if I鈥檓 being reasonable.
Simon Scarle
University of Manchester Institute of Science and Technology, UK
This week鈥檚 questions
Liver building
The human liver is said to be a 鈥減rivileged鈥� organ, because it can regenerate more than 80 per cent of its volume within only two months following surgery. Such a rate of growth exceeds that of most solid tumours. This raises two questions: what triggers the start of this extremely rapid growth, and perhaps even more importantly, what causes it to stop at the right point?
Heiner Biesel
Sandy, Utah, US
Living on stone
There is a brick chimney stack near my home in Hemel Hempstead in southern England that has a tree growing out of it, and I have seen similar trees on rock faces and cathedral spires. How do these plants survive? Where do their roots go? Young trees in my garden struggle in well-tended, well-fed soil. How can a 1-metre tree survive in what is essentially a brick wall?
Jane Stephens
Hemel Hempstead, Hertfordshire, UK
Water, water, everywhere
How can oceanographers tell the average depth of the ocean? In calculations of sea levels, currently considered a matter of great importance, they can seemingly tell to the nearest centimetre if the water is rising or falling. Surely even on a windless day the ocean surface rises and falls by more than a few centimetres, simply due to local wave action, not to mention the changes caused by tides and swells.
Roger Sharp
By email, no address supplied