The theoretical limit of sensitivity in any measurement is determined by the noise generated by the resistances present in the circuit.

测量灵敏度的理论极限取决于在电路中的电阻所产生的噪声。

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This will, by necessity limit the sensitivity of this category (i.e. some lead-related deaths are missed).

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"Personally, I think that having some threshold would give some more uniformity to the test, but pragmatically we don't want to limit the sensitivity of tests, " said Prof David Cowan from King's College London, who is in charge of anti-doping at next summer's London Olympic Games.

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