Digital cameras tend to be upgraded every few months, often with only subtle changes.

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But with the help of a guide like Dr Crump, subtle changes in the balance of nature can be observed: with the limpet population practically wiped out by the oil, the particular seaweed they used to feed on was allowed to thrive, changing the look of the rocks.

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Though these changes can go unnoticed by a person with a disease, relatives and friends more often pick up on it, but a computer algorithm that detects nuances of speech and subtle changes could detect abberations with much greater frequency.

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Our own busy lives may cause us to be less than conscious of the subtle changes and warning signs that parents need our attention, especially with money.

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The new design sees subtle changes to the controller, which gets a more ergonomic form with extended grips and a tapered shape to better sit in the hand.

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The three different sizes of live tiles on the start screen is the obvious change, but there are more subtle changes inside the core applications and in the underlying code that developers work with.

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