AMS 14C Dates and Major Element Composition of Glass Shards of Late Pleistocene Tephras on Tanegashima Island, Southern Japan

Four late Pleistocene tephra layers—Tane I (Tn1), II (Tn2), III (Tn3), and IV (Tn4) in ascending order—are intercalated between widespread tephras, Kikai-Tozurahara (K-Tz: 95 ka) and Aira-Tn (AT: 30 cal kBP), on Tanegashima Island, in southern Japan. Paleolithic ruins such as the Yokomine C and Tatikiri archaeological sites were excavated from the loam layer between the Tn4 and Tn3 tephras. To refine the chronological framework on the island, we conducted accelerator mass spectrometry (AMS) radiocarbon dating for 2 paleosol and 6 charcoal samples related with the late Pleistocene tephras and the Yokomine C archaeological site. The obtained 14C dates are consistent with the stratigraphy in calendar years, 33 cal kBP for Tn4, 40 cal kBP for Tn3, and 50 cal kBP for Tn2 and Tn1. The charcoal dates from Yokomine C, 32–38 cal kBP, not only constrain the age of Tn4 and Tn3 ashes, but also serve as a possible date for the site. We also measured the major element compositions of volcanic glass shards with EDS-EPMA to characterize these tephras. Although we could not find a possible correlative for Tn3 and Tn4 ashes using major element oxides of the glass shards, i.e. 75–76 wt% in SiO2, the glass chemistry obtained in this study will be valuable in correlating these tephras with their source volcanoes in the near future.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Structural aging of human neurons is the opposite of the changes in schizophrenia

Human mentality develops with age and is altered in psychiatric disorders, though their underlying mechanism is unknown. In this study, we analyzed nanometer-scale three-dimensional structures of brain tissues of the anterior cingulate cortex from eight schizophrenia and eight control cases. The distribution profiles of neurite curvature of the control cases showed a trend depending on their age, resulting in an age-correlated decrease in the standard deviation of neurite curvature (Pearson's r = -0.80, p = 0.018). In contrast to the control cases, the schizophrenia cases deviate upward from this correlation, exhibiting a 60% higher neurite curvature compared with the controls (p = 7.8 x 10^(-4)). The neurite curvature also showed a correlation with a hallucination score (Pearson's r = 0.80, p = 1.8 x 10^(-4)), indicating that neurite structure is relevant to brain function. We suggest that neurite curvature plays a pivotal role in brain aging and can be used as a hallmark to exploit a novel treatment of schizophrenia. This nano-CT paper is the result of our decade-long analysis and is unprecedented in terms of number of cases.Comment: 24 pages, 5 figures. arXiv admin note: text overlap with arXiv:2007.0021

Recent Results from LHD Experiment with Emphasis on Relation to Theory from Experimentalist’s View

he Large Helical Device (LHD) has been extending an operational regime of net-current free plasmas towardsthe fusion relevant condition with taking advantage of a net current-free heliotron concept and employing a superconducting coil system. Heating capability has exceeded 10 MW and the central ion and electron temperatureshave reached 7 and 10 keV, respectively. The maximum value of β and pulse length have been extended to 3.2% and 150 s, respectively. Many encouraging physical findings have been obtained. Topics from recent experiments, which should be emphasized from the aspect of theoretical approaches, are reviewed. Those are (1) Prominent features in the inward shifted configuration, i.e., mitigation of an ideal interchange mode in the configuration with magnetic hill, and confinement improvement due to suppression of both anomalous and neoclassical transport, (2) Demonstration ofbifurcation of radial electric field and associated formation of an internal transport barrier, and (3) Dynamics of magnetic islands and clarification of the role of separatrix

Paleomagnetism of Miocene Rocks in the Western Area of Baragoi, Northern Kenya

A total of 22 reliable paleomagnetic data has been obtained from Miocene rocks in this area. The magnetic polarity sequence is divided into six magneto-zones, which are tentatively correlated with the geomagnetic reversal time scale. The Kenyapithecus horizon is assigned to a normal epoch in the period between 14 Ma and 12 Ma. The VGPs obtained from this area show the deviations in the direction of the "far-sided and right-handed" effect from the geographical pole

Strontium concentrations in saline lake waters in the Dry Valleys region of Southern Victoria Land, Antarctica

The Sr concentrations of saline lake waters collected from the Dry Valleys region of Victoria Land were determined and the Sr/Ca ratios were evaluated. These waters have various Sr/Ca ratios ranging from 0.0 to 4.56×(10)^. It was observed that the Sr/Ca ratios of inland lake waters were smaller than those of the lakes near the Ross Sea. On the basis of the Sr/Ca ratios the origin of lake waters in the Dry Valleys region is summarized as follows : 1) The water in Lake Fryxell was originated from evaporated seawater under frigid conditions, because the Sr/Ca ratio of the water, about 3 to 4×(10)^, is similar to that of evaporated seawater from which halite is deposited. This water may have been formed by mixing of the evaporated seawater with glacial meltwater. It is likely that the water in Lake Bonney was also formed in a similar manner to that of Lake Fryxell. 2) The water in Lake Vanda was originated from glacial meltwater containing dissolved marine evaporites. The evaporites such as calcite and gypsum in the valley may have been formed under frigid conditions as delineated by T. G. THOMPSON and K. H. NELSON (Am. J. Sci., 254,227,1956). 3) The water in the Labyrinth area was probably originated from the dissolution of air-borne salts by glacial meltwater and snowfall and the waters drived from fresh water-basalt interactions