Usefulness of powdered crown of mandibular first premolars in birth year estimation by radiocarbon dating.

Background: Radiocarbon (C), whose levels increased in the atmosphere between 1955 and 1963, accumulates in the enamel of human teeth only during the process of tooth formation and has been applied to estimate the birth year of unidentified corpses. However, enamel isolation from teeth is time-consuming and labor-intensive. Therefore, this study aimed to estimate the birth year using C in the crown of a single mandibular first premolar tooth.

Gradual onset of the Maunder Minimum revealed by high-precision carbon-14 analyses.

The Sun exhibits centennial-scale activity variations and sometimes encounters grand solar minimum when solar activity becomes extremely weak and sunspots disappear for several decades. Such an extreme weakening of solar activity could cause severe climate, causing massive reductions in crop yields in some regions. During the past decade, the Sun's activity has tended to decline, raising concerns that the Sun might be heading for the next grand minimum.

Prolonged production of C during the ~660 BCE solar proton event from Japanese tree rings.

Annual rings record the intensity of cosmic rays (CRs) that had entered into the Earth's atmosphere. Several rapid C increases in the past, such as the 775 CE and 994CE C spikes, have been reported to originate from extreme solar proton events (SPEs). Another rapid C increase, also known as the ca.

Estimation of birth year by radiocarbon dating of tooth enamel: Approach to obtaining enamel powder.

Atmospheric radiocarbon (C) levels increased from 1955 to 1963 due to atmospheric nuclear weapon tests, and then decreased. As C accumulates in human tooth enamel while the enamel is being formed, C can be used to estimate the birth year of unidentified bodies. Measurement results of C content in tooth enamel using accelerator mass spectrometry vary depending on the enamel's sample site.

Developments of the theory of spin fluctuations and spin fluctuation-induced superconductivity.

Theory of spin fluctuations as developed in the past 30 years have played important roles in the theory of magnetism in metals, particularly in elucidating the properties around the magnetic instability or quantum critical points. Recently the theory has been extended to deal with the spin fluctuaion-mediated superconductivity with anisotropic order parameters in strongly correlated electron systems. These theoretical developments are briefly reviewed and the high temperature superconductivity of cuprates and organic and heavy electron superconductors are discussed in the light of these theories.