the British Association festival in Newcastle
A ROYAL Marines officer saved 20,000 civilians from drowning at the hands of Serbian dam-busters, it was revealed yesterday.
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The unsung hero, Captain Mark Gray, 29, from Devon defied land mines and booby traps to open a sluice gate on top of the Peruca dam in Croatia shortly before the occupying Serbs detonated explosives deep inside it.
His audacious feat two years ago has been unknown to the public until described to the Science Festival yesterday by engineering Professor Paul Pack from Oxford University.
He described how Serbian militia had expelled UN observers from the 65-metre-high dam in January, 1993, and set off huge explosives in a maintenance gallery that ran the dam's length at foundation level.
''This was an attempt to use the 540 million cubic metres of stored water as a weapon of mass destruction to the downstream land and population,'' said Professor Pack.
''Some 20,000 people would have been drowned or rendered homeless had the dam failed as intended.''
Severe damage was caused to three points in the dam corresponding to where the saboteurs had placed their explosives. In the central section alone it was estimated that 15 tons of explosive had been used.
At each of these three points the top of the dam -- made of rock fill with a clay core -- sagged by two metres, said Professor Pack, who was a member of a British team despatched by the Overseas Development Administration to inspect it and advise on repairs after the Croatians reoccupied it.
''During the tenure of the UN observers, but while the dam was in Serb hands, the British major, who had trained as an engineer, had visited the site and observed that the Serbs were holding the water level well above the correct full supply level,'' he said.
''On his own initiative, and exceeding his authority, he opened the surface spillway gate sufficiently to slowly reduce the water level. He managed to lower the water level by some metres by the time the attempt to destroy the dam took place.
''Had he not been able to reduce the level, there is no doubt that the dam would have failed as water would have poured over the slumped crest after the explosions.''
As it was, Professor Pack said it was only a miracle that the dam had not failed. With gunfire echoing in the hills engineers had to race against time before the ongoing erosion of the dam's clay core caused a blow-through and total collapse.
Professor Pack said he learned later that the officer could have been disciplined for exceeding his authority.
''I wrote to the Ministry of Defence and told him he should be given a medal instead.''
Earlier, it was learned that drug experts have closed a loophole that was enabling athletes to cheat with impunity.
Extensive research on natural levels of the hormone dihydrotestosterone will allow sports authorities to make charges stick against athletes who boost their levels artificially.
Dihydrotestosterone is a metabolite of the male hormone testosterone; it occurs naturally in males and, to a lesser extent, in females, but in both cases the levels vary from one individual to another.
Dr David Cowan, from the Drug Control Centre at King's College, London, said: ''Thanks to extensive population testing we now have the data setting out the parameters for its natural occurrence. This has enabled us to set threshold levels beyond which we can say with authority that the levels have been boosted artificially, and the disciplinary bodies will have the data to back them up.''
The use of dihydrotestosterone came to prominence last year when Chinese swimmers accused of using it were disqualified from the Asian Games.
It binds to receptors in the muscle, giving added size and strength, in the bones, boosting the manufacture of red blood cells, and in the brain, where it arouses a more aggressive and competitive edge.
It can be obtained in the form of a fine powder, mixed with whisky, and rubbed on to the chest, where it will penetrate the skin, said Dr Cowan.
Although it does not produce acute toxic effects, long-term use can lead to kidney and liver damage.
But higher levels, within the normal parameters, may be good news. Tests on Greek army recruits, published recently in the Lancet, showed that the higher the levels they had the more orgasms they achieved in the course of a week.
Meanwhile, Dr Cowan and his colleagues have turned their attention to other cheating agents which have proved difficult to detect, and hope to crack them too.
In another medical breakthrough, saliva tests may soon be used to determine when workers are over-stressed and need a break.
The tests will go under trial next year on business executives and footballers.
Excessive stress can lower resistance to infection, said former athlete Dr Lynn Fitzgerald, Reader in Sports Science at Brunel University.
''Accountants are prone to herpes towards the end of the financial year when they are struggling to get their books balanced,'' she said.
''Athletes are pushing themselves harder than ever before, and more are suffering from illness -- colds, sore throats and flu, post-vital fatigue syndrome, and chronic fatigue.
''Infections result in poor performance, with weeks or even months of training lost.''
Although some stress was no bad thing, there was a well-established link between psychological stress and immune competence, she added.
Cortisol, adrenalin, and neuropeptides are released during psychological stress as well as during physical exercise.
''The effects on the immune system of the physical stresses of elite athletes appear to be cumulative,'' said Dr Fitzgerald. ''Each exhaustive training session or competition compromises the immune system for a few hours, which provides an opportunity for infections to take hold.''