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.

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.

Possible involvement of AMPK in acute exercise-induced expression of monocarboxylate transporters MCT1 and MCT4 mRNA in fast-twitch skeletal muscle.

Objective: The regulatory mechanisms responsible for acute exercise-induced expression of monocarboxylate transporters MCT1 and MCT4 mRNA in skeletal muscle remain unclear. 5'-adenosine-activated protein kinase (AMPK) is a key signaling molecule that regulates gene expression at the mRNA level. We examined whether AMPK activation is involved in acute exercise-induced expression of MCT1 and MCT4 mRNA in fast-twitch muscle.