Another important push was the onset of the Little Ice Age, a climatic phenomenon that led to cooler temperatures in the Northern Hemisphere.

另一个重要的推动因素是小冰期的开始，这一气候现象导致北半球气温下降。

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In many countries with good measles control, an increasing age at onset of SSPE has been observed attributable to cases that acquired measles infection at a time when the disease was more prevalent.

在许多麻疹已经得到很好控制的国家SSPE的发病年龄有增高趋势，观察发现这些病例都是因为在过去麻疹较严重流行时期感染了麻疹的缘故。

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The average age was 63 at the study's onset.

研究开始时，她们的平均年龄为63岁。

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When dysthymia starts before age 21, it's called early-onset dysthymia.

CNN: Dysthymia