Seasonal variations of δ 13 C were analyzed for two Japanese cypress trees ( Chamaecyparis obtusa ), one buried and one living. Both trees were different in age but sampled in areas geographically close to each other in central Japan. A buried cypress with 394 annual rings was excavated from Old Fuji mudflow, the last glacial strata of the dormant Mt. Fuji volcano. The accelerator mass spectrometry (AMS) radiocarbon date of this glacial sample was 18,600 ± 120 BP (NUTA–4884). A living tree stem, which has 192 rings, was cut from the Izu Peninsula in 1986. In order to measure the seasonal δ 13 C fluctuation, the tree rings were divided equally into three earlywood and one or two latewood consecutive sections. The δ 13 C value within an annual ring generally increased from the first to the third or fourth sections then decreased in the last section. This pattern of the variation was similar in the glacial and modern samples. The δ 13 C value within an annual ring seems to be controlled by environmental factors (not plant physiological ones), since there was no isotopic shift in the seasonal δ 13 C variation at the earlywood-latewood boundary, which was controlled by plant physiology. The result suggests the potential to reconstruct the paleoenvironment within a year using the seasonal δ 13 C variation, though site-specific conditions such as soil characteristics would also affect to its fluctuation.
Gastrointestinal duplications are uncommon congenital malformations that can occur anywhere along the gastrointestinal tract.Most cases are recognized before the age of 2 years, and those encountered in adults are rare.We describe here a case of ascending colon duplication in a 20-year-old male that caused intussusception and was treated laparoscopically.Although computed tomography revealed a cystic mass filled with stool-like material, the preoperative diagnosis was a submucosal tumor of the ascending colon.We performed a laparoscopic right colectomy, and the postoperative pathological diagnosis was duplication of the ascending colon, both cystic and tubular components.We conclude that gastrointestinal duplications, although rare, should be considered in the differential diagnosis of all abdominal and submucosal cystic lesions and that laparoscopy is a preferred approach for the surgical treatment of gastrointestinal duplications.
Thermokarst formation and vegetation change in central Yakutia, eastern Siberia, were reconstructed based on newly obtained AMS radiocarbon data and pollen records from four typical thermokarst depressions (alases). Radiocarbon ages of wood fragments, which are good indicators of the development of thermokarst depressions, suggest that they formed during the early Holocene. The result of dating at various locations implies that thermokarst in central Yakutia developed synchronously, at a time that regional paleoclimate records indicate warm and moist conditions prevailed. Major trends in pollen records from the four thermokarst deposits were similar. The predominant vegetation type during the thermokarst active phase was open larch and birch forest with herbaceous taxa. Grassland developed on areas exposed by a decrease in water levels of thermokarst lakes during the late Holocene.
ABSTRACT We obtained radiocarbon ( 14 C) dates with accelerator mass spectrometry (AMS) of vascular plant samples and a charcoal sample collected from peat deposits near the prehistoric village site informally designated CR-03 on Carlisle Island in the Islands of Four Mountains group, Alaska, to determine the eruption age of the CR-02 tephra. A fine vitric ash erupted from Okmok caldera, Umnak Island (ca. 2 ka BP) was also discovered in the bog. The ages of the CR-02 tephra and Okmok II ash are estimated to be 1050 and 2000 cal BP, respectively. Because both tephras are distinctive and widespread, these are important chronostratigraphic markers for archaeological sites in this island group. The 14 C dates obtained from this bog are 800 years younger than the dates of the charcoal fragments from cultural layers in the Unit 3 of prehistoric village site CR-02 (AMK-0003).
ABSTRACT The open-system pingos of Spitsbergen are formed outside terminal moraines, fault zones, and delta areas. Pingos in this study area were located near the shore in active geologic uplift areas. Three open-system pingos in the Adventdalen delta area of Spitsbergen were examined. Pingos closer to shore are younger in age and those farther away are older. Growth of these pingos occurs rapidly after initial submarine uplift and a minimum thickness of permafrost is established. Hut pingo, which is farthest from the sea, was formed after 6980±70 a BP (NUTA-3856). Driftwood associated with Longyear pingo, in the middle part of the delta, was dated at 2800±90 a BP. The radiocarbon age of peat near the shore pingo, Lagoon pingo, was 140±20 a BP. The growth of the pingos is related to transgression and development of permafrost.
