• Gakushuin Natural Radiocarbon Measurements I

      Kigoshi, Kunihiko; Tomikura, Y.; Endo, Kunihiko (American Journal of Science, 1962-01-01)
    • Gakushuin Natural Radiocarbon Measurements II

      Kigoshi, Kunihiko; Endo, Kunihiko (American Journal of Science, 1963-01-01)
    • Gakushuin Natural Radiocarbon Measurements III

      Kigoshi, Kunihiko; Lin, Der-Hwang; Endo, Kunihiko (American Journal of Science, 1964-01-01)
    • Gakushuin Natural Radiocarbon Measurements IV

      Kigoshi, Kunihiko; Kobayashi, Hiromi (American Journal of Science, 1965-01-01)
    • Gakushuin Natural Radiocarbon Measurements V

      Kigoshi, Kunihiko; Kobayashi, Hiromi (American Journal of Science, 1966-01-01)
    • Gakushuin Natural Radiocarbon Measurements VI

      Kigoshi, Kunihiko (American Journal of Science, 1967-01-01)
    • Gakushuin Natural Radiocarbon Measurements VII

      Kigoshi, Kunihiko; Aizawa, Hiroko; Suzuki, Nobuko (American Journal of Science, 1969-01-01)
    • Gakushuin Natural Radiocarbon Measurements VIII

      Kigoshi, Kunihiko; Suzuki, Nobuko; Fukatsu, Hiroko (American Journal of Science, 1973-01-01)
    • Gamma Flux in 14C Laboratories

      Theodórsson, Páll; Kaihola, Lauri; Loosli, H. H.; Rodríguez, José M. (Department of Geosciences, The University of Arizona, 1992-01-01)
      An informal collaborative group of radiocarbon dating laboratories, the Low-Level Club, has been established to measure the gamma radiation flux and to test the efficiency of the anticoincidence counting system in laboratories with a NaI detector unit. The detector will record gamma radiation from cosmogenic nuclides, muons and secondary y radiation formed in the passive shield by charged cosmic-ray particles. We present here the first phase of this work.
    • Gas Counting System for 14C Dating of Small Samples in the Kraków Laboratory

      Gorczyca, Zbigniew; Jeleń, Kazimierz; Kuc, Tadeusz (Department of Geosciences, The University of Arizona, 1998-01-01)
      The application of traditional gas or liquid scintillation counting (LSC) is necessary for assessing radionuclide activity in countries without operating accelerator mass spectrometry (AMS) facilities. A simple and relatively inexpensive system of mini gas counters for measurement of radiocarbon in archaeological and environmental samples has been set up recently in the Kraków laboratory (Department of Environmental Physics, University of Mining and Metallurgy). The system is composed of a gas purification and counter filling line, three identical 15-mL copper/quartz counters, active and passive shielding, and an electronic unit with data acquisition. One counter measures 22 mg of carbon as CO2 with efficiency >95% at a background reduced to 0.044 cpm by a NaJ(T1) guard counter and lead shield. The detection limit (1 sigma) for a two-week measurement of 48 mL of CO2 is 0.52 pMC. The corresponding counting error of a 100 pMC environmental sample is 1.3 pMC for 22 mgC (one counter) and 0.75 pMC for 66 mgC (three counters filled with the sample).
    • Gas Exchange Rate Measurements in Natural Systems

      Broecker, W. S.; Peng, T.-H.; Mathieu, G.; Hesslein, R.; Torgersen, T. (American Journal of Science, 1980-01-01)
      Rates of CO, exchange across the air-water interface in oceans and lakes measured to date by the L-DGO group are summarized. They range from 3 to 38 moles/m2/yr. The possible causes for this range include the differences in salinity, mean wind speed, and pH. Wind tunnel studies comparing fresh water and sea water are required before a satisfactory explanation can be found.
    • Gas Proportional Versus Liquid Scintillation Counting, Radiometric Versus AMS Dating

      Theodórsson, Páll (Department of Geosciences, The University of Arizona, 1991-01-01)
      I discuss here the basis of a comparison of methods for radiocarbon dating and introduce a new index for the relative merit of a system, factor of counting capacity, that is generally more appropriate than the commonly used factor of merit. The merit of a dating system cannot be based on a single figure but other factors must also be considered. A comparison of the gas proportional, liquid scintillation and accelerator mass spectrometry technique is presented that for gas proportional counters is based on a multi-detector system rather than a single detector.
    • Genotoxicity Study on Nicotine and Nicotine-Derived Nitrosamine by Accelerator Mass Spectrometry

      Li, X. S.; Wang, H. F.; Shi, J. Y.; Wang, X. Y.; Liu, Y. F.; Li, K.; Lu, X. Y.; Wang, J. J.; Liu, K. X.; Guo, Z. Y. (Department of Geosciences, The University of Arizona, 1996-01-01)
      We have studied DNA adduction with 14C-labe1ed nicotine and nicotine-derived nitrosamine, 4-(methylnitrosamino)1-(3-pyridyl)-1-butanone (NNK), by accelerator mass spectrometry (AMS) in mouse liver at doses equivalent to lowlevel exposure of humans. The dose ranges of nicotine and NNK administered were from 0.4g to 4.0x 10^2 micrograms kg b.w.-1, and from 0.1 micrograms to 2.0x10^4 micrograms kg b.w.-1, respectively. In the exposure of mice to either nicotine or NNK, the number of DNA adducts increased linearly with increasing dose. The detection limit of DNA adducts was 1 adduct per 1011 nucleotide molecules. This limit is 1-4 orders of magnitude lower than that of other techniques used for quantification of DNA adducts. The results of our animal experiments enabled us to speculate that nicotine is a potential carcinogen. According to the procedure for 14C-labeled-NNK synthesis, we discuss the ultimate chemical speciation of NNK bound to DNA. From the animal tests we derived a directly perceivable relation between tobacco consumption and DNA adduction as the carcinogenic risk assessment.
    • Geochron Laboratories, Inc. Radiocarbon Measurements I

      Krueger, Harold W.; Weeks, C. Francis (American Journal of Science, 1965-01-01)
    • Geochron Laboratories, Inc. Radiocarbon Measurements II

      Krueger, Harold W.; Weeks, C. Francis (American Journal of Science, 1966-01-01)
    • Geochronologic and Paleoclimatic Characterization of Quaternary Sediments in the Great Hungarian Plan

      Hertelendi, Ede; Sümegi, Pål; Szöör, Gyula (Department of Geosciences, The University of Arizona, 1992-01-01)
      We reconstructed the climate of the Great Hungarian Plain between the years, 7-32 ka BP using a malacothermometer method. The reconstruction is based on seven Gastropoda taxa, for which optimal temperature and tolerance ranges have been determined. The temporal scales of the malacofaunal levels were calibrated with radiocarbon data. We compared our paleotemperature values with the temperature values of existing climatic curves and found the same climatic periods.
    • Geochronology of Late Quaternary Events in Northeastern Russia

      Lozhkin, A. V. (Department of Geosciences, The University of Arizona, 1993-01-01)
      Radiocarbon-dated paleobotanical and palynological samples record complex changes of vegetation and climate in northeastern Russia during the Late Pleistocene and Holocene. Since the Kargin Interval (middle Wisconsin equivalent), which started 50 ka ago, we can distinguish two periods that were colder than the present. The Kirgilyakh was the earliest Karginsk cool period, dating to 45–39 ka BP. The second significant cool period dates to 33–30 ka BP. The boundary between the Kargin Interval and the last Late Pleistocene glaciation (Sartan, late Wisconsin equivalent) dates from 27 ka BP. The sharp change from herbaceous mossy tundra (Sartan) to light-coniferous larch forests (Holocene) in northeastern Russia dates to 12.5 ka ago. The Holocene thermal maximum, linked to the expansion of woody plants into the modern barren-ground tundra, dates from 9.5–8 ka BP.
    • Geochronology of the Holocene of the Belorussian Polessie

      Matveev, A. V.; Krutous, E. A.; Zernitskaya, V. P. (Department of Geosciences, The University of Arizona, 1993-01-01)
      We distinguished major stages of the last glaciation (Bulling, Older Dryas, Allerod, Younger Dryas) and the Holocene by radiocarbon dating and paleobotanical analyses. Our paleobotanical investigation of peatlands is well correlated with independent 14C data. We establish that the Atlantic and Subboreal stages of the Holocene have three divisions, and that the Subatlantic has two.
    • Geochronology of the Nival-Glacial Deposits of the Ukrainian Carpathian Mountains

      Kovalyukh, N. N.; Petrenko, L. V.; Kovalenko, V. V. (Department of Geosciences, The University of Arizona, 1993-01-01)
    • Geochronology of the Pleistocene and Holocene in the Fore-Urals

      Latypova, E. K.; Yakheemovich, B. L. (Department of Geosciences, The University of Arizona, 1993-01-01)
      The paper presents the results for the 14C dating obtained recently in the Laboratory of the Institute of Geology, Ufa Science Centre, Russian Academy of Science, on the basis of megafaunal bones, peats, wood and mollusk shells. Dates are reported in stratigraphic sequence from the Late Wurmian to the Holocene.