由此产生的聚落地图显示，公元500年至公元850年，科潘古城崩溃时，城市周围农村人口的分布和密度发生了巨大变化。

The resulting settlement maps show how the distribution and density of the rural population around the city changed dramatically between AD 500 and 850, when copán collapsed.

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不过当涉及到群体的密度增加，运行变得混乱时，对于预测发生的变化往往不能奏效。

But it often fails to predict the changes that happen as a crowd's density increases and its movement becomes chaotic.

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一特定地区发生的火灾次数和该地区的人口密度密切相关。

There is a close correlation between population density and the number of fires in a given region.

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The calorie density has changed because food is processed, so the calories in the fat and the sugar that can get squeezed into things made possible by technological changes has shifted things a lot.

食品经过加工,热量密度发生了变化,添加到食品中的脂肪和糖类,其卡路里含量可通过技术手段进行调整,进而造成很大不同

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选