Very early risers and longtime night owls have a hard time ever changing, says David F. Dinges, chief of sleep and chronobiology at the University of Pennsylvania's Perelman School of Medicine.

宾夕法尼亚佩雷尔曼医学院睡眠和时间生物学主任大卫·丁格斯说，起得很早的人和长时间的夜猫子很难突然改变。

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Now, researchers at the Perelman School of Medicine at the University of Pennsylvania are the first to demonstrate the direct conversion of a non-heart cell type into a heart cell by RNA transfer.

现在，宾夕法尼亚大学佩雷尔曼医学院的研究人员首次人为地实现由非心肌细胞直接转化成心肌细胞。

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George Cotsarelis, professor and chair of dermatology at the Perelman School of Medicine at the University of Pennsylvania, in Philadelphia, is skeptical of product claims.

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Koop was born in Brooklyn, New York, and attended Dartmouth, Weill Cornell Medical College and the Perelman School of Medicine at the University of Pennsylvania.

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Samantha Pfeifer, an associate professor of obstetrics and gynecology at the Perelman School of Medicine at the University of Pennsylvania, says the test is usually used to determine what dose of fertility medicine to use for IVF.

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