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In this example , November rainfall was delivered as a single 3-day tropical storm event and resulting flooded field conditions demanded unusually high discharges . Nonpoint source pollution does not result from a single definable location , such as an industrial discharge pipe , but rather results from land runoff , precipitation , atmospheric deposition , or percolation . Preliminary genetic results suggest that this may be a single recessive gene , with a number of modifying factors which usually hold down the expression of this fundamentally teratological condition . Guinea worm is a painful and debilitating parasitic disease whose effects reach far beyond a single victim-crippling agricultural production , impacting household food security , reducing school attendance , and influencing many other facets of life . Putting it even more starkly : Taking the low-point of oil prices at the end of 1998 ( USD10 per barrel Brent ) and thus interpreting the developments since then as a single prolonged oil price shock , the scale of the shock is greatly magnified .