منابع مشابه
Early formation of the Moon 4.51 billion years ago
Establishing the age of the Moon is critical to understanding solar system evolution and the formation of rocky planets, including Earth. However, despite its importance, the age of the Moon has never been accurately determined. We present uranium-lead dating of Apollo 14 zircon fragments that yield highly precise, concordant ages, demonstrating that they are robust against postcrystallization ...
متن کامل0 The nuclear interaction at Oklo 2 billion years ago ∗
We re-examine the effort to constrain the time-variability of the coupling constants of the fundamental interactions by studying the anomalous isotopic abundance of Sm observed at the remnants of the natural reactors which were in operation at Oklo about 2 billion years ago, in terms of a possible deviation of the resonance energy from the value observed today. We rely on new samples that were ...
متن کاملOrbital forcing of climate 1.4 billion years ago.
Fluctuating climate is a hallmark of Earth. As one transcends deep into Earth time, however, both the evidence for and the causes of climate change become difficult to establish. We report geochemical and sedimentological evidence for repeated, short-term climate fluctuations from the exceptionally well-preserved ∼1.4-billion-year-old Xiamaling Formation of the North China Craton. We observe tw...
متن کاملGeriatrics one hundred years ago.
JUST OVER A century ago, Daniel Maclachlan, Physician to the Royal Hospital, Chelsea, published his book The Diseases and Infirmities of Advanced Life. This was based on his extensive experience among the Chelsea pensioners as well as patients seen in private practice. He begins by stating 'the diseases of advanced and declining life have been comparatively neglected ... they have nowhere recei...
متن کاملThe Nuclear Interaction at Oklo 2 Billion Years Ago *
We re-examine Shlyakhter’s effort to constrain the time-variability of the coupling constants of the fundamental interactions by studying the anomalous isotopic abundance of Sm observed at the remnants of the natural reactors which were in operation at Oklo about 2 billion years ago. We rely on new samples that were carefully collected to minimize natural contamination and also on a careful tem...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Natural Resources
سال: 2013
ISSN: 2158-706X,2158-7086
DOI: 10.4236/nr.2013.45047