bluuebunny/crossref_metadata_2025_split huggingface dataset:
Illinois State Geological Survey Radiocarbon Dates I
Authors: Kim Stephen M. , Ruch R. R. 
Published: July 2016

The radiocarbon dating laboratory of the Illinois State Geological Survey has been established to satisfy a growing need for radiocarbon dates for an active Pleistocene research program. Because of the age and type of material dated, the benzene liquid scintillation counting method is employed in this laboratory. The detailed chemical procedure for converting carbon to benzene has been published by Noakes, Kim, and Stipp (1965) and Noakes, Kim, and Akers (1967); however, the procedures for benzene synthesis and sample counting are briefly explained below to clarify this laboratory's procedure.An organic sample, such as peat, organic silt, or wood, is burned and the CO2 evolved is absorbed in NH4OH. SrCl2 solution is added to precipitate the carbonate, and the solution plus precipitate is boiled and cooled before filtration of SrCO3. The SrCO3 is acidified with dilute H3PO4 to liberate CO2 in a closed system, and the CO2 is converted to C2H2, as reported by Barker (1953). In this method, 2.4 gm of dry packed lithium, obtainable from the Lithium Corporation of America, is used for each liter of CO2 that is converted to C2H2. Trimerization of the C2H2 to form C6H6 is accomplished using a vanadium-alumina catalyst.To the C6H6 synthesized from the sample carbon, 2 cc of toluene containing 100 mg Butyl-PBD, 2-(4-tert-Butylphenyl)-5-(4-Biphenylyl)-1,3,4-Oxadiazole, are added, and this mixture is made to a total volume of 10 cc with spectrograde C6H6. A modified Packard Instrument Co. liquid scintillation spectrometer (Model 3375) is used for measurement of C14 activity.Ages are calculated from a C14 half-life of 5568 years, and the standard deviation (1σ) is based only on counting errors; however, if calculated error is less than 200 years, 200 years is chosen as one standard deviation (1σ).
University of Rome Carbon-14 Dates VII
Authors: Alessio M. , Bella F. , Cortesi C. , Turi B. 
Published: July 2016

We list measurements carried out between June and November 1968. Archaeologic samples are from Italian and Swat (W Pakistan) territories; all geologic samples are from Italian territory.Chemical preparation of samples, measurement technique, and the modern standard are unchanged (Bella and Cortesi, 1960; Alessio, Bella, and Cortesi, 1964; Alessio et al., 1968).For each sample of CO2 the counting rate was corrected according to mass-spectrometrically measured C13/C12 ratio. Isotopic analyses were carried out with a 6 in., 60°-sector, double-collecting mass spectrometer, designed and built by G. Boato at Ist. di Fisica, Univ. of Genoa (Boato et al., 1960) and now in use at Ist. di Geochim., Univ. of Rome. C13/C12 ratio is reported as δ-value, the deviation in parts per mil of the C13/C12 ratio of sample from the PDB standard:
Yale Natural Radiocarbon Measurements IX
Authors: Stuiver Minze 
Published: July 2016

The present list represents a major portion of the samples measured since publication of the last date list in 1963. As in previous lists, dates are reported in terms of the 5568 yr half-life. Infinite dates are reported as beyond a limit equal to 2σ above background. Nearly all of the samples were measured in one of three quartz counters with backgrounds of 0.7 to 1.2 cpm per liter of effective counting volume at working pressures of about two atmospheres. The age errors quoted are based only on the standard deviations in counting rates of sample and standards.The various C14 projects of the Radiocarbon Laboratory have been supported by the National Science Foundation, Grants GP 4879 and GA 1157; the tree ring research has been supported by the Atomic Energy Commission under contract AT (30-1) 2652. Technical assistance has been provided by Carolyn H. Morgan and Terry C. Eisensmith.
Optimization of Liquid Scintillation Counting Conditions With Two Kinds of Vials and Detector Shields for Low-Activity Radiocarbon Measurements
Authors: Rauret Gemma , Mestres J S , Garcia J F 
Published: July 2016

Low-level radiocarbon measurements were made using two liquid scintillation (LS) counters, both with passive lead shields of approximately the same dimensions. The first one had a conventional background reduction with low-activity lead and “high-low” coincidence bias selection, and the second one had a spectrum analysis background reduction based on the different three-dimensional pulse-height signal of background and beta pulses.
The performance of commercial teflon-copper and glass vials were compared with both LS counters. Optimum counting conditions for the two detectors studied were also established. From results obtained, quality parameters and characteristics of quench curves were studied. Performances of each counter in the working conditions established were also compared.
University of Rome Radiocarbon Dates XVII
Authors: Alessio Marisa , Allegri Lucia , Improta Salvatore , Belluomini Giorgio , Cortesi Cesarina , Manfra Luigia , Turi Bruno 
Published: July 2016

This list includes dates from Italy, Libyan Sahara, Niger and the Dahlak Islands, obtained from 1976 to 1980, using the benzene scintillation method.Chemical processing from sample to benzene follows procedures of Alessio et al (1978a). Standard pretreatment for wood and charcoal included boiling with 5–10% HCL.
Storage Conditions and Physical Treatments Relating to the Dating of the Dead Sea Scrolls
Authors: Caldararo Niccolo 
Published: July 2016

The Dead Sea Scrolls have been analyzed by paleographic, non-destructive and destructive testing. The dates of their creation have been in dispute since their discovery. Research has established their authenticity, but a variety of conditions including the methods of skin preparation, variation in storage conditions and post-discovery restoration treatments could have introduced changes now affecting dating efforts. Comprehensive analyses were not possible until recently. Such analysis must be performed to establish a concrete framework for all the texts.Professor R. B. Blake told a story in response to a question of why so little remained of writing on leather. He said that on one of his expeditions to Asia Minor, one of his native servants exhibited proudly some chamois trousers of his own manufacture, upon which Professor Blake detected with sorrow, traces of medieval writing (Reed 1972).
First 14C Results from Archaeological and Forensic Studies at the Vienna Environmental Research Accelerator
Authors: Wild Eva , Golser Robin , Hille Peter , Kutschera Walter , Priller Alfred , Puchegger Stephan , Rom Werner , Steier Peter , Vycudilik Walter 
Published: July 2016

14C dating with the new Vienna Environmental Research Accelerator (VERA) began with the age determination of a mummified marmot found in the Austrian Alpine region. Soft tissue and bones of the marmot were used for the investigation. For comparison, bone material from known-age samples was also processed and measured. These exercises showed that 14C dating with VERA is reliable, and since that time various samples from archaeological context have been dated.We also studied the applicability of the 14C method in forensic sciences to determine the time of death of human individuals. 14C/12C measurements of samples from different organic human material (bone collagen, lipids from bone and bone marrow, hair) were performed and compared with the tropospheric “bomb peak” values to transform the measured ratios into “calibrated ages”. For specific substances with rapid turnover rates, this gives an estimate for the time of death of the individual. In our study, lipids and hair yield reasonable times of death, whereas the collagen fraction from bones, which has a relatively long turnover time, is not suitable for this purpose.
Factors Influencing 14C Ages of the Pacific Rat Rattus Exulans
Authors: Beavan Nancy Ragano , Sparks Rodger J. 
Published: July 2016

An isotopic database for the Pacific/Polynesian rat (Rattus exulans) and foods that it scavenges is used to examine diet-induced 14C age variation in omnivores. We discuss a suite of 26 δ14C determinations and 13C and 15N analysis for modern Pacific/Polynesian rat bone gelatin and available food items from Kapiti Island, New Zealand (40°51'S, 174°75'E). These analyses provide the first isotopic data for modern specimens of the species, collected as part of a larger project to determine potential sources of bias in unexpectedly old 14C age measurements on subfossil specimens of R. exulans from New Zealand. Stable C, N and 14C isotopic and trapping data are used to trace carbon intake via the diet of the rats in each habitat. Data from specimens linked to five specific habitats on the island indicate that modern populations of R. exulans are not in equilibrium with atmospheric values of δ14C, being either enriched or depleted relative to the atmospheric curve in 1996/97, the period of collection. The δ14C values recorded for R. exulans are associated with diet, and result from variation in δ14C values found in animal-protein food items available to a scavenging omnivore. The titer of carbon deviating from atmospheric values is believed to be derived from the essential amino acids in the protein-rich foods of the rat diet.Present evidence suggests that the depletion required to affect 14C ages limits the possibility that diet introduces dramatic offsets from true ages. Marine diets, for example, would have a variable effect on ages for terrestrial omnivores, contraindicating the application of a standard marine correction for such specimens. We suggest that to identify the extent to which diet may influence the 14C age in a given specimen of terrestrial omnivore, the separation and dating of essential amino acids vs. a nonessential amino, such as glycine, be applied.
14C Dating of Laminated Sediments from Loch Ness, Scotland
Authors: Cooper M. C. , O'Sullivan P.E. , Harkness D. D. , Lawson E. M. , Bull D. , Kemp A. E. S. , Peglar Sylvia M. , Matthews Nina M. , Jones R. I. , Shine A. J. 
Published: July 2016

Radiometric and AMS radiocarbon dating of a 6-m sediment core from Loch Ness, Scotland, indicates that it represents perhaps the very end of the Late Pleistocene, and the first ca. 7500 yr of the Holocene. Counts of laminations observed in the Holocene section of the core suggest that they are present in sufficient number to constitute annual laminations (varves), an hypothesis consistent with the pollen record, which contains a sequence of zones representative of the Early, Middle and part of the Late Holocene regional vegetation history. On the basis of BSEM and X-ray studies of sediments, and modern seston trap data, the laminations are believed to be produced by winter floods, which introduce increased silt loading into the Loch. Sediment for the rest of the year is mostly composed of clay-sized material. This hypothesis is being further tested, however, by continuing sedimentological and microfossil studies.Time-depth relations for the core based on calibrated 14C dates and lamination counts, respectively, illustrate the close correspondence between the two sets of data. The latter are therefore now being used to develop a varve chronology for the Holocene for Loch Ness. This will then in turn be used for further chronological studies, and for investigations of palaeoclimatic variations over the eastern North Atlantic, to which the signal of lamination thickness in the sediments is thought to be particularly sensitive. They may also eventually be used for calibration studies, employing 14C dating of specific carbon compounds, or groups of compounds extracted from the sediment using modern organic geochemical methods.
Using 14C as a Tracer of Carbon Accumulation and Turnover in Soils
Authors: Milton G. M. , Kramer S. J. 
Published: July 2016

Three very different Canadian soils—clay soils of the St. Lawrence Lowlands, sandy forest soils of the Ottawa Valley, and organic-rich sediments from a wetland on the Canadian Shield—have been cored, sliced and separated into different density fractions, and the radiocarbon content of these soil fractions measured. In two of the areas sampled, cores were obtained close to operating nuclear reactors, as well as from beyond their region of influence. As a consequence, it has been possible to ascertain the depths of penetration of both the weapons-testing pulse (peaking in 1963), and a 25–50-yr chronic reactor input of 14C.The percentage of carbon stored in different density fractions varied with soil type. Turnover times for bulk soil organic carbon, estimated from soil degassing rates, have been compared with those predicated on the residual “bomb” 14C in background cores, and/or on the ratio of reactor-emitted 14C retained in the soils to the total deposited during the lifetime of operation. Residence times for the heavy carbon fraction present at depths below the influence of anthropogenic inputs have also been estimated.The accumulated data will be incorporated in a revised soil model, adjusted for the parameters deemed to be most important to carbon turnover rates under Canadian conditions.
Lamont Natural Radiocarbon Measurements VII
Authors: Olson Edwin A. , Broecker Wallace S. 
Published: July 2016

Radiocarbon-age measurements reported here were made at Lamont Geological Observatory between July 1958 and November 1960. Sample descriptions are classified as follows:
I.Samples associated with glacial depositsII.Samples associated with marine coastal depositsIII.Samples associated with marine coastal deposits uplifted by glacial reboundIV.Samples associated with pluvial-lake depositsV.Samples from deep-sea coresVI.Samples from cave depositsVII.Miscellaneous samples of geologic interestVIII.Samples of archaeologic interest
University of Barcelona Radiocarbon Dates I
Authors: Mestres J. S. , Rauret Gemma , Garcia J. F. 
Published: July 2016

The Radiocarbon Laboratory at the University of Barcelona began its serial measurements in 1985. The following list contains dates obtained between 1985 and 1987. Both archaeological and geological samples were dated.The measurement technique we use is liquid scintillation counting of benzene. A previous paper (Mestres, García & Rauret 1991) describes sample pretreatment, synthesis and counting protocols and equipment.
Late Holocene Climatic Change in the Balkans: Speleothem Isotopic Data from Serbia
Authors: Kacanski Aleksander , Carmi Israel , Shemesh Aldo , Kronfeld Joel , Yam Ruth , Flexer Akiva 
Published: July 2016

A detailed profile of the stable isotopes of carbon and oxygen was obtained from a speleothem (stalagmite) from the Ceremosjna Cave in eastern Serbia. The stalagmite is a low magnesian calcite that did not show any evidence of diagenetic alteration. It was precipitated under isotopic equilibrium conditions from dripping water. The age and rate of deposition was derived from six internally consistent radiocarbon dates. The initial 14C activity was determined to be approximately 80 pMC. The stalagmite appears to preserve a continuous record of calcite deposition from approximately 2300 BP until the present.Oxygen isotopic data, based upon 100 samples, are used to derive the first paleotemperature record for Serbia. A regression analysis of the all the data indicates that over the period of time that the speleothem was deposited there was a general trend of lowering of the average temperature. Superimposed upon this are significant long-term temperature fluctuations. These can be divided into four broader climatic groupings. Going from the oldest times to the present, there are two warm periods separated by a period when the temperatures fell below the temperature trend line. However, the absolute temperatures were generally above those of the more recent period that is generally characterized by the coolest climatic conditions.
Radiocarbon Dates of Riga I
Authors: Veksler V S 
Published: July 2016

The Riga Radiocarbon Laboratory began its serial measurements in 1971. Radiocarbon activity is measured by solution scintillation counters. Benzol, obtained by acetylene trimerization on vanadium pentoxide activated silicagel, is used as 14C activity carrier. The dates refer to 1950 according to the 5568-year half-life of 14C. The statistical error is 1σ (Veksler, Putans & Savvaitov, 1971).We present data here of samples from coastal regions of the USSR, which reflect their geologic-geomorphologic development (Veksler et al, 1975; Veksler, Putans & Stelle, 1977; Veksler & Prede, 1986).
The Impact of Radiocarbon Dating on Old World Archaeology: Past Achievements and Future Expectations
Authors: Bar-Yosef O 
Published: July 2016

Half a century since radiocarbon was first used in the archaeology of the Old World, it seems that the expectations of W F Libby may be becoming a reality. In 1952 (Libby 1952:97), he wrote:Archaeologists, geologists and palynologists are continually searching for the means to improve methods of counting time. The … relative chronologies lack precision and direct correlation with the calendar, except when they may be checked with, … for example, the calendar based on tree-ring counts.
Reporting 14C Activities and Concentrations
Authors: Mook Willem G , van der Plicht Johannes 
Published: July 2016

Three modes of reporting 14C activities are in use, in part analogous to the internationally accepted (IAEA) conventions for stable isotopes: (1) absolute activity, the specific activity of 14C or the activity per gram of carbon; (2) activity ratio, the ratio between the absolute activities of a sample and the standard; and (3) relative activity, the difference between the absolute activities of a sample and standard material, relative to the absolute standard activity. The basic definitions originate from decisions made by the radiocarbon community at its past conferences. Stuiver and Polach (1977) reviewed and sought to specify the definitions and conventions. Several colleagues, however, have experienced inadequacies and pitfalls in the definitions and use of symbols. Furthermore, the latter have to be slightly amended because of the use of modern measuring techniques.This paper is intended to provide a consistent set of reporting symbols and definitions, illustrated by some practical examples.
Anthropogenic Influence on the 14C Activity and Other Constituents of Recent Lake Sediments: A Case Study1
Authors: Srdoč Dušan , Horvatinčić Nada , Ahel Marijan , Giger Walter , Schaffner Christian , Bronić Ines Krajcar , Petricioli Donat , Pezdič Jože , Marčenko Elena , Plenković-Moraj Anđelka 
Published: July 2016

Anthropogenic activities that introduce an excess of nutrients and other pollutants into rivers and lakes are causing significant changes in their aquatic environment. Excessive nutrients greatly accelerate eutrophication, and lake marl formed during eutrophication differs from that formed in oligotrophic water.We analyzed recent sediment cores from Prošće and Kozjak lakes located in Plitvice National Park, central Croatia. Analyses consisted of 14C activity of calcareous lake marl, the ratio of stable isotopes (δ13C, δ18O), organic compounds in the sediment and the distribution of diatoms. Previous 14C activity measurements helped to determine the sedimentation rate and thus the time period of increased input of nutrients into lakes. We determined the increased 14C activity in lake sediments caused by nuclear bomb effect in recent depth profiles. We attributed the sudden increase in diatom species, Cyclotella operculata unipuctata and Achnanthes clevei rostrata, in the uppermost 5-cm layer, to eutrophication of the lake water.We performed a molecular characterization of hydrocarbons isolated from the sediments, and applied computer-assisted high-resolution gas chromatography/mass spectrometry to estimate contributions of biogenic, fossil and pyrolytic hydrocarbons.
Novel Statistical Model for a Piece-Wise Linear Radiocarbon Calibration Curve
Authors: Aguilar Delil Gómez Portugal , Litton Cliff D , O'Hagan Anthony 
Published: July 2016

The process of calibrating radiocarbon determinations onto the calendar scale requires the setting of a specific statistical model for the calibration curve. This model specification will bear fundamental importance for the resulting inference regarding the parameter of interest—namely, in general, the calendar age associated to the sample that has been 14C-dated.Traditionally, the 14C calibration curve has been modelled simply as the piece-wise linear curve joining the (internationally agreed) high-precision calibration data points; or, less frequently, by proposing spline functions in order to obtain a smoother curve.We present a model for the 14C calibration curve which, based on specific characteristics of the dating method, yields a piece-wise linear curve, but one which rather than interpolating the data points, smooths them. We show that with this specific model if a piece-wise linear curve is desired, an underlying random walk model is implied as covariance structure (and vice versa). Furthermore, by making use of all the information provided by the calibration data in a comprehensive way, we achieve an improvement over current models by getting more realistic variance values for the calibration curve.
Modelling the Spectral Energy Distributions of AGB Stars in the LMC
Authors: Groenewegen M. A. T. , Van Loon J. Th. , Whitelock P. A. , Wood P. R. , Zijlstra A. A. 
Published: July 2016

The spectral energy distributions of 16 AGB stars in the LMC are fitted. The 6 known oxygen-rich stars are well fitted with silicate dust. Due to the completely different absorption properties of silicate and carbonaceous dust we argue that of the 10 stars of unknown spectral type, 1 is probably O-rich while the other 9 are probably C-rich.The Period-Luminosity relation is discussed. Both the O- and C-rich LPVs in this study appear to lie on extensions of P-L relations derived for stars with much shorter periods.
Spark-chamber observation of galactic γ-radiation
Authors: Hutchinson G. W. , Pearce A. J. , Ramsden D. , Wills R. D. 
Published: July 2016

A γ-Ray telescope incorporating an acoustic spark chamber is included in the payload of the OGO-5 spacecraft. The performance of the instrument, which is sensitive to photons of energy 25 to 100 MeV, is discussed.Observations are limited to a portion of the sky near Cygnus, but the first month's data indicate a variation of intensity showing a maximum in the direction of the galactic plane. If this plane contains a line source of radiation, its intensity is found to be (9 ± 5) × 10−4 photons cm−2 sec−1 rad−1 above an energy of 40 MeV.
Origin of the cosmic X-ray background:(Invited discourse)
Authors: Setti G. , Rees M. J. 
Published: July 2016

In this paper we review the theories which have been proposed to account for the extra-galactic X-ray background. Although there is still no detailed theory, one may devise reasonable models which account in a natural way both for the intensity and the spectral shape over the whole energy band, provided that cosmological evolutionary effects are included. A model based on Compton scattering of cosmic black body photons by relativistic electrons in radio sources at large redshifts (z≳ 4) seems to give the most satisfactory explanation. However, the data are not yet good enough to discriminate against alternative models.A discussion of the recent observations in the soft X-ray region (< 1 keV), and their relevance to the physics of interstellar and intergalactic gas, is given. The available data are somewhat confusing, but it seems that this part of the spectrum may still be consistent with a simple extrapolation of the non-thermal spectrum at higher energies, though various workers have claimed the detection of a new component probably due to hot intergalactic gas. If this interpretation is correct one may deduce interesting conclusions about the state of ionization and composition of the intergalactic gas, because of the importance of the absorption effects in this energy band.Also it appears that the Galaxy is more transparent than one would deduce from 21-cm observations. However, due to the lack of observational data, no firm conclusions can be reached.