But whilst working on large-scale energy projects in developing countries, she also realized that the pressing needs of many poor individuals were still not being served.

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We cannot stop pressing our leaders to help struggling poor and middle-class Americans.

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Mr Singer's influence extends to the world beyond the ivory tower partly because he writes with such lucidity and quiet passion about genuinely pressing questions: the environment, the rich-poor divide, cruelty to animals, human suffering.

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"The most pressing problem is that the mechanical and electrical systems are in a poor state of repair, which is why we have embarked on a five-year programme of aggressive maintenance to mitigate against the most serious equipment failures, " he said.

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