bluuebunny/crossref_metadata_2025 huggingface dataset:
Southwest Subtropical Pacific Surface Water Radiocarbon in a High-Resolution Coral Record
Authors: Guilderson Thomas P , Schrag Daniel P , Goddard Ethan , Kashgarian Michaele , Wellington Gerard M , Linsley Braddock K
Published: July 2016

We have generated a high-resolution coral Δ14C record from the southwest subtropical Pacific spanning the last 50 yr. Prebomb (1950–1956) Δ14C values average −52%. Values begin to increase in 1957, reaching a maximum in the early 1970s, about 10 yr after the atmospheric peak. There is a consistent 10–15% seasonal cycle whose relationship with vertical mixing evolves as a consequence of the penetration of the bomb transient into subsurface waters. Comparison of this record with that simulated in an ocean general circulation model highlights the difficulty in modeling vertical exchange processes.
Redating Iztapan and Valsequillo, Mexico
Authors: Pichardo Mario
Published: July 2016

Recent radiocarbon dating of tephra sequences and biostratigraphic analysis in the Valley of Mexico and the Valley of Puebla, respectively, reveal that the FAD (first appearance date) for lanceolate Lerma/El Jobo points at Iztapan and Hueyatlaco archeological sites at about 14–16,000 BP predates the Clovis culture FAD. A lack of interdisciplinary communication is responsible for the neglect of these sites for three decades.
Texas A&M University Radiocarbon Dates II
Authors: Mathews T. D. , Fredericks A. D. , Sackett W. M.
Published: July 2016

The radiocarbon laboratory in the Oceanography Department at Texas A&M University was established primarily for the examination of seawater samples, although other types of samples have been run. Emphasis has been placed on seawater samples of the Gulf of Mexico and adjacent areas. Most of the samples examined have been inorganic carbon, but some organic-carbon samples are being run, mainly wood and charcoal whose ages have been determined previously. More samples of known age will be run as a further check on the reliability of experimental methods and procedures.
Spatial and Temporal Distribution of Radiocarbon Ages on Rodent Middens from the Southwestern United States
Authors: Webb Robert H
Published: July 2016

The analysis of rodent middens, principally deposited by packrats (Neotoma sp), has rapidly become the most important paleoecologic and paleoclimatologic tool in the southwestern United States. The recent discovery of rodent middens created by stick-nest rats (Leporillus sp) and rock wallabies (Petrogale sp) in Australia (Green et al, 1983; P S Martin, oral commun, 1984) and by dassie rats (Petromus typicus) in South Africa (L Scott, oral commun, 1984) portends the use of midden analysis in arid regions worldwide. Several recent reviews of southwestern paleoecology (eg, Spaulding et al, 1983) rely heavily on rodent middens for ecologic and climatic reconstructions.
Institut Royal du Patrimoine Artistique Radiocarbon Dates XI
Authors: Dauchot-Dehon Michele , Strydonck Mark Van , Heylen Jos
Published: July 2016

This list contains the results of 14C determinations obtained at the laboratory in 1984. Our laboratory measures 14C activity in the form of methane with a proportional counter built by Heidelberg University and an electronic unit built by Berthold, Benelux Analytical Instruments. The sample counting time is 4000 minutes with printouts at 100 minute intervals. Sample error is reported as one standard deviation. δ13C for mortar is measured by the University of Lyon Laboratory, δ13C was not measured or estimated for other samples.
Illinois State Geological Survey Radiocarbon Dates VIII
Authors: Liu Chao Li , Riley Kerry M , Coleman Dennis D
Published: July 2016

This article reports on archaeologic samples processed from February 1974 through May 1980 at the Illinois State Geological Survey (ISGS) Radiocarbon Dating Laboratory.
High-Precision Calibration of the Radiocarbon Time Scale, AD 1950–500 BC
Authors: Stuiver Minze , Pearson Gordon W
Published: July 2016

Radiocarbon ages of dendrochronologically-dated wood spanning the last 4500 years were determined at both the Seattle and Belfast laboratories. The combined results are reported in this issue ofradiocarbonin two papers, with this paper covering the AD 1950—500 BC interval, and the twin (Pearson & Stuiver, 1986) covering the 500 BC–2500 BC interval.
High-Precision Decadal Calibration of the Radiocarbon Time Scale, AD 1950–2500 BC
Authors: Stuiver Minze , Becker Bernd
Published: July 2016

The radiocarbon ages of dendrochronologically dated wood samples, each covering 10 years, are reported back to 2500 yr BC. The decadal calibration curve constructed from these data is an extension of the curve previously given for the AD interval (Stuiver, 1982). A major difference with the previous work, however, is the assessment of the error in the radiocarbon age determination. Whereas previously this error was only based on the Poisson counting statistics of the accumulated number of counts for the sample and standards, the current calibration error is based on an estimate of the reproducibility in the radiocarbon activity determination. As a consequence, the uncertainty in the current calibration curve is, on average, 1.6 times that of the AD curve previously given.
Problems in Radiocarbon Dating of Soils
Authors: Chichagova O. A. , Cherkinsky A. E.
Published: July 2016

We discuss our progress in three principal applications of 14C dating of recent and fossil soils: 1) new methods; 2) problems of interpreting 14C soil data (e.g.,14C age of soils, age of soils, duration of humus formation, rate of carbon cycling); and 3) 14C analysis of soil organic matter (OM) in pedology and paleogeography (e.g., soil genesis and evolution, humus formation and OM metamorphosis, geochronology and stratigraphy of Late Pleistocene and Holocene sediments). We suggest exploring the above issues in the analysis of each 14C profile in conjunction with paleogeographical data, and by simulation of the carbon cycle in each type of profile.
Late Pleistocene Geochronology of European Russia
Authors: Arslanov Kh. A.
Published: July 2016

I constructed a Late Pleistocene geochronological scale for European Russia employing 14C dating and paleobotanical studies of several reference sections.
Geochronology of the Nival-Glacial Deposits of the Ukrainian Carpathian Mountains
Authors: Kovalyukh N. N. , Petrenko L. V. , Kovalenko V. V.
Published: July 2016

The few studies of the paleogeography of the Ukrainian Carpathians include the chronology of relief formation (Demeduke 1971), the development of vegetation (Malinovsky 1980) and the formation of the landscape (Miller 1961). Previous paleographic inferences were based on comparisons with natural alpine cycles (Koziy 1950, 1963; Tsys 1955, 1968; Tretyak and Kuleshko 1982). Neighboring areas to the west and south of the Ukrainian Carpathians are also insufficiently studied (Serebrany 1978).
Radiocarbon Chronology of Early Medieval Archaeological Sites in Northwestern Russia
Authors: Popov S. G. , Svezhentsev Yu. S. , Zaitseva G. I.
Published: July 2016

A reliable archaelogical chronology for medieval sites in northwestern Russia depends in part on a refined regional calibration scale for 14C dates. We present results of dates on tree-ring series from Novgorod that show a systematic discrepancy from European calibration curves, and that underline the need for more extensive 14C dating as the basis of an extended calibration curve for the region.
Late Paleolithic Chronology of the East European Plain
Authors: Svezhentsev Yu. S. , Popov S. G.
Published: July 2016

We report 172 dates on osseous material from Paleolithic sites of the East European Plain.
Rapid Production of Graphite Without Contamination for Biomedical AMS
Authors: Vogel John S.
Published: July 2016

The application of AMS to the detection of 14C makes possible a new class of sensitive experiments in molecular biology. Such experiments inherently produce large numbers of samples for the determination of biological variability in molecular interactions. The samples vary in 14C concentration over many orders of magnitude. We added TiH2 to aid the reduction of CO2 by zinc in a sealed tube to reproducibly make graphite without sample cross-contamination. The CO2 is transferred from a combustion tube to the reaction tube through a disposable plastic manifold. The sealed tubes are heated to a single-reaction temperature in a muffle furnace. The process is complete within 5 h. Bulk isotopic fractionation in the finished graphite is less than 0.5%.
High-Sensitivity Radiocarbon Dating in the 50,000 to 70,000 bp Range without Isotopic Enrichment
Authors: Long Austin , Kalin Robert M.
Published: July 2016

Calculations show the possibility of detecting14C remaining after 10 or 11 decay half-lives in natural materials, such as wood, using commercially available liquid scintillation (LS) detectors. Assumingin-situ14C production has contributed insignificantly to the measured14C, one can calculate finite ages approaching 70 ka. In practice, defensible finite age determinations involve careful considerations of several critical elements in the procedure. These critical elements are: 1) the integrity of the sample itself, in terms of younger contaminants and ofin situ-produced14C; 2) the availability of “dead” background material; 3) chemical blank in laboratory preparation of, in this case, benzene; and 4) stability of background and efficiency of the LS counting system. High-sensitivity14C dating reveals a low level of memory effect14C in benzene synthesized in the laboratory from anthracite or marble. This level of14C activity is equivalent to that found in 53 ka old wood, and thus, is not distinguishable from petrochemical benzene used in routine dating. If careful control of laboratory conditions can maintain this14C blank constant, reproducible dating beyond 53 ka would be possible. Although we have not completed a systematic analysis of the origins of memory effect, lithium reactors used in acetylene production and organic solvents in wood pretreatment are likely sources.
A Radiocarbon Dating Protocol for use with Packard Scintillation Counters Employing Burst-Counting Circuitry
Authors: Cook G. T. , Anderson Robert
Published: July 2016

Considerable research has been carried out in this laboratory on the use of Packard scintillation counters employing burst-counting circuitry. The nature of the pulse-shape discrimination circuit has led to redefining our sample vialing philosophy and scintillation cocktail optimization. Results presented here demonstrate: 1) the enhancements in efficiency that are achievable using a two-component cocktail compared with the use of a primary fluor only; 2) the development of a cocktail in which efficiency and quenching are relatively unaffected by moderate variations in fluor concentrations and ratio; 3) the rationale behind the use of screw-cap vials rather than sealable ampules; 4) the advantage of nickel/chromium-plated brass caps over standard plastic caps.
Quantifying Background Components of Low-Level Gas Proportional Counters
Authors: Theodórsson Páll
Published: July 2016

I discuss background components of low-level gas proportional counters and show how each component can be estimated based on available data. For more reliable background analysis, further studies are suggested. Based on new information, a generation of low-level gas proportional counting systems for radiocarbon dating may emerge with lower and more predictable background.
Radiocarbon AMS Dating of Pollen Extracted from Peat Samples
Authors: Brown T. A. , Farwell G. W. , Grootes P. M. , Schmidt F. H.
Published: July 2016

We present 14C AMS measurements and discuss the extraction procedure used on pollen extracted from peat samples. Microscopic examination of the extracts shows that the procedure is sufficient to remove most non-pollen materials and results in an extract that is composed predominantly of pollen. The 14C dates that we obtained for pollen extracts from peat samples associated with the Mazama Ash layer are consistent with the range of bulk-sample dates obtained by others in previous studies. The limited measurement time and resulting precision (± 100 yr) of these initial measurements restrict our ability to draw firm conclusions from a comparison of the pollen extract dates with previous bulk-sample dates. We intend to adjust our procedure to improve the rejection of non-pollen materials and to increase the precision of our 14C measurements on pollen extracts from peat samples in future studies.
Evaluating Dissolved Inorganic Carbon Cycling in a Forested Lake Watershed Using Carbon Isotopes
Authors: Aravena Ramon , Schiff S. L. , Trumbore S. E. , Dillon P. J. , Elgood Richard
Published: July 2016

Dissolved inorganic carbon (DIC) is the main acid buffer in forested lake watersheds in Canada. We used carbon isotopes (13C, 14C) to evaluate the production and cycling of DIC in an acid-sensitive lake watershed of the Precambrian Shield. Soil CO2, groundwater and stream DIC were characterized chemically and isotopically. Soil CO2 concentration profiles reflect both changes in production and in losses due to diffusion. δ13C soil CO2 profiles (δ13C values of −23‰ in summer, slightly enriched during the fall and −25%‰ during the winter) are a reflection of the isotopic composition of the sources and changes in isotopic fractionation due to diffusion. Carbon isotopic composition (13C, 14C) of the groundwater and stream DIC clearly indicate that weathering of silicates by soil CO2 is the main source of DIC in these watersheds. 14C data show that, in addition to recent groundwater, an older groundwater component with depleted 14C activity is also present in the bedrock. The carbon isotope pattern in the groundwater also implies that, besides the main springtime recharge events, contributions to the groundwater may also occur during late winter/early spring.
Radiocarbon Dating of Groundwater in a Confined Aquifer in Southeast Arizona
Authors: Robertson Frederick N.
Published: July 2016

Radiocarbon, δ13C and major-element data were used to construct a geochemical framework for interpretation of the hydrological flow system in the lower San Pedro basin, southeastern Arizona, USA. The14C and major-element data show a regional confined aquifer that extends throughout most of the basin. Groundwater ages, after correcting for chemistry, are greater than 10 ka bp. The groundwater ages do not increase in a downvalley direction, the assumed direction of groundwater movement in most intermontane basins in the region, but along general flow paths normal to the mountains toward the center of the basin. Recharge to the confined aquifer originates from infiltration of precipitation and runoff near the alluvium-mountain contact along the Galiuro Mountains and is discharged by evapotranspiration along the center of the basin. The hydrogeological concept of the14C model is supported by the water chemistry and by the mass transfer defined by the chemical model. Weathering of primary silicate minerals in the confined aquifer does not occur downvalley, but only along the direction of flow. Hydraulic conductivities calculated for the aquifer from14C velocities are about an order of magnitude slower than those determined through hydrological methods. The lower hydraulic-conductivity values are attributed to a thick confining layer overlying the discharge area along the San Pedro River.
14C Dating of Groundwater Containing Microbial CH4
Authors: Hackley K. C. , Liu C. L. , Coleman D. D.
Published: July 2016

Groundwater samples were collected from several different depths in Illinois glacial deposits at a site in east-central Illinois. Dissolved gases were extracted from many of the water samples, measured volumetrically, and analyze by gas chromatography. The DIC was precipitated as barium carbonate and analyzed for both δ13C and 14C. Due to the formation of microbial CH4, some of the DIC had unusually heavy δ13C values of −3 to −1‰. The standard groundwate 14C-age correction models were developed to account for carbonate dissolution as the primary carbon input beneath the soil zone. If the heavy δ13C values observed in this study are used in readily available groundwater dating models without accounting for the effect of microbial methane formation, many of the resultant calculated ages are negaitive (future ages) mathematically unsolvable. Isotopic and analytical result show a positive correlation (r2 = 0.90) between the δ13C of the DIC and the concentration of methane in the groundwater. With this correlation, we were able to correct the δ13C values of the DIC which were altered due to microbial CH4 formation. This adjustment of δ13C values, along with estimation of dead carbon input from the redox processes, allowed us to calculate 14C ages using standard groundwater age correction models.
Radiocarbon Anomalies Observed for Plants Growing in Icelandic Geothermal Waters
Authors: Sveinbjörnsdóttir Árný E. , Heinemeier Jan , Rud Niels , Johnsen Sigfús J.
Published: July 2016

We have studied plant remains in thick beds of lacustrine sediments in the upper part of the Markarfljót drainage area in southern Iceland. We collected small samples of plant species from the same horizon and14C dated them at the Aarhus AMS Dating Laboratory. Terrestrial plants yielded an age of 9 ka BP, whereas aquaic moss (Fontinalis antipyreticaHedw.) yielded the surprisingly old14C age of 16 ka bp. We believe the age of the terrestrial plants reflects the true age of the sediment. The anomalously old14C age of the aquatic moss may be an effect of geothermal water on the moss, as the area is known to be geothermally active today. Modern aquatic moss growing in geothermal water showed a similar14C anomaly, with measured ages ranging from 6 to 8 ka BP, which may be explained by the equally old ages measured for the corresponding water samples. The14C content of geothermal springs and neighboring rivers in the area ranges from 9 to 50 pMC, equivalent to an apparent age of 20–5.5 ka bp.
Measurements of Cosmogenic 14C Produced by Spallation in High-Altitude Rocks
Authors: Jull A. J. T. , Wilson Amy E. , Burr George S. , Toolin Laurence J. , Donahue Douglas J.
Published: July 2016

The production of radioisotopes at the Earth's surface by cosmic-ray effects has been discussed for many years. Only in the past few years, with the higher sensitivity provided by accelerator mass spectrometry (AMS) in detecting 10Be, 26A1 and 36Cl, have the radioisotopes produced in this way been measured. We report here our measurements of cosmogenic 14C in terrestrial rocks at high altitude, and comparisons to other exposure-dating methods.
Common Spectral Features in the 5500-Year Record of Total Carbonate in Sea Sediments and Radiocarbon in Tree Rings
Authors: Castagnoli Giuliana Cini , Bonino Giuseppe , Serio Marina , Sonett Charles P.
Published: July 2016

We analyze here the time record of total carbonate carried as CaCO3 in a sea-bottom core from the Ionian Sea. Several major periods appear, most strongly at 1100, 690, 500, 340, 250 and 90 yr, confirmed both in the periodogram and maximum entropy estimates. The Gleissberg period appears in common with the 14C and other records, such as the sunspot index and aurorae. The manifestation of this period in what we surmise to be a climatic record is further evidence that the Gleissberg period has correlated bolometric and electrodynamic aspects.
The Impact of Accelerator Dating at the Early Village of Abu Hureyra on the Euphrates
Authors: Moore A. M. T.
Published: July 2016

The early village of Abu Hureyra is significant because of its great size (ca. 11.5 ha) and long sequence of occupation (ca. 11,500–7000 bp) that spans the transition from late Pleistocene hunting and gathering to early Holocene farming, and the cultural change from Epipaleolithic to Neolithic. The 40 accelerator dates obtained for Abu Hureyra provide new information on the development of agriculture in Southwest Asia. The dates have demonstrated that the site was inhabited for much longer than the few conventional radiocarbon dates for the site had suggested. The gap between the Epipaleolithic and Neolithic villages seems to have been brief. A change in climate and vegetation, dated at ca. 10,600 BP, during the span of occupation of the Epipaleolithic village, precipitated an adjustment in the foraging way of life of its inhabitants just before the inception of agriculture. Dating of individual bones and seeds has shown that the wild progenitors of sheep and several cereals were present near Abu Hureyra in the late Pleistocene and early Holocene, well outside their present areas of distribution. This has implications for where those species may have been domesticated. A rapid switch from exploitation of the gazelle to herding of sheep and goats during the Neolithic occupation occurred ca. 8300 bp.
Radiocarbon Dating of Copper-Preserved Organics
Authors: Beukens R. P. , Pavlish L. A. , Hancock R. G. V. , Farquhar R. M. , Wilson G. C. , Julig P. J. , Ross William
Published: July 2016

The small but vital role of 14C dating in archaeometric research is clearly shown in the copper project reported herein. The 14C ages place a time perspective on the “Old Copper Culture Complex,” substantiating early Libby dates that had been questioned. The respective roles of INAA, PGE and Pb isotope work are briefly summarized. A long tradition of heat treatment from Paleoindian stone to Archaic copper is suggested.
Dating Precolumbian Museum Objects
Authors: Van Strydonck Mark J. Y. , Van Der Borg Klaas , de Jong Arie F. M.
Published: July 2016

We have radiocarbon dated some Precolumbian artifacts. We have used both conventional beta counting and AMS to date textiles, bamboo from weaving looms, a feather carpet and straw from a clay mask. We discuss the particular problems in sample pretreatment.
Carbon-Isotope Fractionation During Wet Oxidation of Oxalic Acid
Authors: Grey D. C. , Damon P. E. , Haynes C. V. , Long Austin
Published: July 2016

The usual procedure for the preparation of carbon dioxide from the oxalic-acid standard supplied by the National Bureau of Standards is wet oxidation by means of potassium permanganate in acid solution. The procedure is straightforward, but suffers from a certain difficulty in determining the end point of the reaction.
Florida State University Radiocarbon Dates III
Authors: Martin J. R. , Goodell H. G.
Published: July 2016

Age calculations in this list include samples dated since January, 1967. Samples are converted to benzene and counted in a liquid scintillation spectrometer. Operations are essentially the same as those described in Radiocarbon, 1966, v. 8, p. 46–53 and Radiocarbon, 1967, v. 9, p. 38–42. Modern reference is 95% the activity of NBS oxalic acid standard, not age-corrected wood as reported in Radiocarbon, 1966, v. 8, p. 46–53.
University of Pennsylvania Radiocarbon Dates XI
Authors: Stuckenrath Robert , Lawn Barbara
Published: July 2016

This date list includes those series of samples completed in this laboratory as of August 1968. The B.P. ages are based upon A.D. 1950, and are calculated with a half-life value of 5568 yr. All samples were counted at least twice for periods of not less than 1000 min each. Errors quoted are derived from measurement of sample, background, and modern age calibration, but do not include any half-life error. All samples were pretreated with 3N HC1, and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic contaminants.
Carbon Dynamics in Vertisols as Revealed by High-Resolution Sampling
Authors: Becker-Heidmann Peter , Andresen Olaf , Kalmar Dov , Scharpenseel Hans-Wilhelm , Yaalon Dan H
Published: July 2016

Two Vertisol soil profiles under xeric soil moisture regimes, located at Qedma and Akko, Israel, were investigated and compared to a profile under ustic moisture regime, located in Hyderabad, India. Samples were taken in complete successive 2 cm thin layers down to about 180 cm depth or more. Organic and inorganic carbon were analyzed with regard to 13C and 14C concentrations. While all soils have radiocarbon ages of several thousand years BP, the depth distributions reveal substantial differences between the soil carbon dynamics. 14C and, less pronounced, δ13C clearly reflect the pedoturbation process. Further, its strength is found to be related to mainly soil moisture regime, then clay content and land use. In one soil, a change of growing from C4 to C3 crops in the past can be concluded from the δ13C depth distribution.
Coastal Response to Changes in Sea Level Since the Last 4500 BP On the East Coast of Tamil Nadu, India
Authors: Achyuthan Hema , Baker V R
Published: July 2016

Geomorphology, clay mineral composition, and radiocarbon dates from Muttukadu to Marakkanam estuaries and the tidal zone along the east coast of Tamil Nadu, India, have been used to reconstruct coastal evolution between approximately 4500 and 1100 B P. Formation of alternate oyster beds with intervening tidal clay units indicate fluctuation in the sea level may be a consequence of changes in the Mid-Holocene sedimentation pattern and coastal configuration. 14C dates from Muttukadu indicate a rapid relative sea-level rise (RSL) subsequent to 3500 BP and tidal flat sedimentation between 3475 and 3145 BP. Marine conditions along the east coast area returned around 1900 B P. Comparison of dates with other sites, e.g. Muttukadu, Mammallapuram, and Marakkanam, points toward short removal of marine conditions, ample sediment supplies in the tidal zones, and neotectonic activity. Reactivation of the north–south trending fault line occurred not earlier than approximately 1050 B P. Our study indicates that Middle to Late Holocene coastal sedimentation and the chronology of the tidal zone formation have been strongly influenced by local factors. These have provided considerable scope for internal reorganization with changing coastal processes.
Marine Radiocarbon Reservoir Corrections for the Mediterranean and Aegean Seas
Authors: Reimer P J , McCormac F G
Published: July 2016

Radiocarbon measurements of nine known age shells from the Mediterranean and the Aegean Seas combined with previous measurements provide an updated value for δR, the local variation in the reservoir correction for marine samples. Comparison of pre-1950s samples from the Algerian coast, with one collected in 1954, indicates early incorporation of nuclear weapons testing14C into the shallow surface waters of the Mediterranean. Comparisons between different basins indicate the surface waters of the Mediterranean are relatively homogenous. The recommended δR for calibration of the Mediterranean marine samples with the 1998 marine calibration dataset is 58 ± 8514C yr, but variations in the reservoir age beyond 6000 cal BP should be considered.
Marine Reservoir Corrections for the Indian Ocean and Southeast Asia
Authors: Southon John , Kashgarian Michaele , Fontugne Michel , Metivier Bernard , W-S Yim Wyss
Published: July 2016

We have measured radiocarbon in prebomb known-age shells and coral from the Indian Ocean and southeast Asia to determine marine reservoir age corrections. Western Indian Ocean results show a strong14C depletion due to upwelling in the Arabian Sea, and indicate that this signal is advected over a wide area to the east and south. In contrast, the surface waters of the South China Sea contain relatively high levels of14C, due in part to the input of well-equilibrated water masses from the western Pacific. The easternmost regions of the Indian Ocean are also strongly influenced by the flowthrough of Pacific waters north of Australia.
Intra-Annual Variability of the Radiocarbon Content of Corals from the Galapagos Islands
Authors: Brown T. A. , Farwell G. W. , Grootes P. M. , Schmidt F. H. , Stuiver Minze
Published: July 2016

We report AMS 14C measurements on subannual samples of coral from the Galapagos Islands that span the period, 1970–1973. Both the major 1972 El Niño/Southern Oscillation event and intra-annual changes in regional upwelling of 14C-depleted waters associated with alternation of surface-ocean current patterns are evident in the record. Our data show that the corals preserve a detailed record of past intra-annual variations of the 14C content of surface ocean water.
An Assessment of the Radiocarbon Dating of the Dead Sea Scrolls
Authors: Rodley G. A.
Published: July 2016

I suggest, on the basis of a statistical analysis, that recently determined “conventional radiocarbon ages” of Dead Sea Scroll documents are offset systematically by about +40 yr, leading to a similar overestimate of the ages of these documents. Much closer agreement with paleographic and specific dates is obtained when a correction of this magnitude is made to the “conventional 14C” values. This indicates that 14C dates may convey more precise information about the ages of these documents than initially recognized.
Seoul National University Accelerator Mass Spectrometry (SNU-AMS) Radiocarbon Date List I
Authors: Kim J C , Youn M Y , Kim I C , Park J H , Song Y M , Kang J , Cheoun M K
Published: July 2016

The accelerator mass spectrometry facility at Seoul National University (SNU-AMS) began functioning in December 1998 and was first reported at the Vienna AMS conference in October 1999 and at the 17th International Radiocarbon Conference in Israel in June 2000. At the Vienna conference, we reported our accelerator system (Kim et al. 2000) and details of the basic sample preparation system (Lee et al. 2000), such as the combustion line to produce CO2; the catalytic reduction line for the graphitization of CO2; and the pretreatment procedures for wood, charcoal, and peat samples. The recent progress of the AMS facility (Kim et al. 2001) and the extension of the sample pretreatment system to iron and bone samples were reported at the 17th International Radiocarbon Conference (Cheoun et al. 2001). In the meantime, extensive testing of accuracy and reproducibility has been carried out, and ∼1000 unknown archaeological and geological samples have been measured every year. In this report, the archaeological, geological, and environmental data carried out in 1999 are presented in terms of yr BP.
The Theatre's Qualified Victory in an Old War
Authors: Johnson Claudia D.
Published: July 2016

After a century-long attack from the Puritan progeny of nineteenth-century America, the theatre by 1860 had long since come to accept as a way of life the religious public's antipathy to the stage. The story of the war between church and theatre is an old but, understandably, not a very popular one with theatre historians; nevertheless, some of the most surprising ironies in American cultural history lie in the dynamics — the death of a president, the death and burial of a respected actor, and an ultimate concession on both fronts — which by the turn of the twentieth century brought a winding down of clerical attacks against the stage and a qualified victory for the comparatively poor, scorned, unorganized theatrical forces over their powerful adversary.
Statistics of spiral patterns and comparison of our Galaxy with other galaxies
Authors: De Vaucouleurs G.
Published: July 2016

Apparent relative frequencies of various types of spirals are given for 900 spirals with the best revised Hubble classifications. Mean diameters of inner ring structures vary from 2.1 kpc in ordinary spirals (SA) to 4.4 kpc in barred spirals (SB) with a total range of 10 to 1 within each type. The probable morphological type of our galaxy is estimated from 6 criteria (multiplicity of spiral pattern, inner ring diameter, broken ring structure, radio structure of nucleus, Yerkes type, HI diagram); arguments advanced in 1963 for an SAB(rs) structure of the inner regions of the galactic system are strengthened by this analysis. Several examples of galaxies in this area of the classification plane are discussed.
Observations of radio continuum emission from M31
Authors: Pooley G. G.
Published: July 2016

Observations of continuum emission from M 31 have been made with the Cambridge One-mile radio telescope (Pooley, 1969). Two observing frequencies were used; maps of the whole of the visible nebula were obtained at 408 MHz, and spectral data for the central region at 1407 MHz. The results show that the radiation from the disc is confined to the nucleus and to the population I spiral arms.

The nuclear region may be described in terms of two spherical radio components, with diameters of 200 pc and 1 kpc. Any more compact source at the nucleus has a luminosity less than 1/20 of that of the source Sgr A in our Galaxy.

The intensity of the radio emission from the spiral arms is closely correlated with the number of H ii regions visible. The main spiral arms, corresponding to Baade's arms 4 and 5, cross the major axis at about 8 and 12.5 kpc from the nucleus. The spectrum of the radiation shows that it is non-thermal in origin; the spectral index is 0.8. The intensity is less than that which would be observed from our own Galaxy at the same distance.
Spiral structure and distribution of stellar associations in NGC 6946
Authors: Khachikian E. Ye. , Sahakian K. A.
Published: July 2016

The associations of NGC 6946 outline its spiral arms. There is no relation between the colour or magnitude of the associations and their distance from the centre. Their mean absolute magnitude is −11m.1 and their mean colour index near zero.
A motion picture film of galactic 21-cm line emission
Authors: Westerhout G.
Published: July 2016

Since 1964 we have been observing 21-cm line profiles in a new survey of the neutral hydrogen distribution in the neighborhood of the galactic plane with the 300-foot radio telescope of the National Radio Astronomy Observatory in Green Bank, W.Va. This is the largest telescope available for 21-cm line work; it has a beamwidth of 10 min of arc and is equipped with an excellent line receiver. Since it seems unlikely that an extensive hydrogen-line survey will be made with any larger telescope, we felt that for reference purposes a concerted effort should be made to obtain as many 21-cm data as possible pertaining to the structure of the Galaxy with this telescope. The data have been presented in the form of contour maps giving the intensity of the 21-cm line radiation as a function of right-ascension and velocity at constant declination. A series of contour maps was distributed to the astronomical community in 1966 as the first edition of the Maryland–Green Bank Galactic 21-cm Line Survey. The second edition, containing 1200 pages and approximately 1800 maps, was distributed in the summer and fall of 1969. It is expected that additional contour maps, completing the survey as originally planned, covering a latitude range from bII = +1° to −1°, lII = 11° to 235° (bII = +3° to −3° between lII = 100° and 145°), will be finished by the summer of 1970. Scans were made across the galactic equator with a stationary telescope, so that the declination is constant through each scan; the declination intervals varied from 4 to 6 min of arc. Eventually, we plan to cover a strip from bII = +5° to −5° between lII = 11° and 235°, containing 225000 independent points at intervals of 6 min of arc, with an effective beamwidth of 12.5 min of arc, a velocity resolution of 2 km s-1, and a total of 1.2 × 108 individual intensities.
On a possible corrugation of the galactic plane
Authors: Varsavsky C. M. , Quiroga R. J.
Published: July 2016

We have studied the rotation curve of the Galaxy at different heights below and above the equator. In the course of this work we noticed that the maximum brightness temperature of hydrogen oscillates around the galactic plane following a fairly sinusoidal pattern. It is further noticed that the maximum temperature of hydrogen occurs right on the plane in the regions where the rotation curve has a form indicating solid body rotation. A rotation curve based on points of maximum hydrogen temperature does not differ appreciably from a rotation curve measured on the galactic plane.
Contribution to the study of the distribution of neutral hydrogen in the region 230° ≤ lII ≤ 280°
Authors: Goniadzki D. , Jech A.
Published: July 2016

A sky survey of the 21 cm hydrogen line has been made with the 100-foot Radiotelescope of the I.A.R.-C.I.W. Radio Astronomy Station in the region 230° ≤ lII ≤ 280°, −15° ≤ bII ≤ −3°.

We study the distribution of the local hydrogen and that in the Orion, Intermediate and Perseus arms. We find a new structure that starts at lII = 265°. We also study the concentrations which lie far below the plane; some of them seem to be related to Lindblad's G arm.
Hydrogen in the regions of four stellar clusters
Authors: Tovmassian H. M.
Published: July 2016

Young clusters of O type and the corresponding stellar associations, together with the associated hydrogen complexes, make up the spiral arms of our Galaxy. Thus the investigation of the distribution of hydrogen and its relation to the clusters is of definite interest.
The galactic distribution of young Cepheids
Authors: Tammann G. A.
Published: July 2016

The distribution of long-period Population I cepheids is studied. An age comparison of cepheids and galactic clusters shows that cepheids with periods > 11.25 d, corresponding to ages of ≲ 30 × 106 yr, should be almost as good spiral arm tracers as galactic clusters with earliest types b 2–3. The distances of cepheids are determined from a revised period-luminosity-colour relation and from colour excesses, for the determination of which a new, purely photometric method is given. The resulting distribution of cepheids shows a good correlation with the spiral arms, as traced by young clusters.
Generating mechanisms for spiral waves
Authors: Lynden-Bell D.
Published: July 2016

To maintain the spiral structure over long periods in spite of the chaotic disturbances so often seen in galaxies it is probably necessary to have a large energy store which is gradually tapped to generate and maintain the spiral wave. Now in a sense stable axially symmetrical model galaxies are configurations of minimum energy for a given angular momentum structure. By a given angular momentum structure I mean that the function μ(h)dh giving the total mass with specific angular momentum between h and h + dh is given and in making the minimum energy statement I have assumed that there is sufficient ‘random’ motion to satisfy Toomre's local stability criterion. To tap a store of energy one must either tap the energy of the whole rotational structure by finding disturbances that may change μ(h), or one may tap the smaller energy store of the ‘random’ motions. Clearly the larger energy store is the more attractive. Now μ(h) is conserved for any axially symmetrical time dependent motions so the only disturbances that can change μ(h) are non-axially symmetrical. If one considers a single star moving in nearly circular motion and interacting with a weak disturbance in the gravitational potential which may be Fourier analysed into components of the form S(R) exp[i(mΦ+ωt)] then one finds that the energy and angular momentum of the star oscillate but do not change in the mean. This statement is untrue when the force due to the wave does not average to zero or when it resonates with the natural oscillation of the star about the circular motion. The angular frequency of the force seen by the star is ω + mΩ, where Ω(R) is the rotational angular velocity of the galaxy, so the exceptions occur at the resonances
Here κ(R) = (4B(B-A))1/2, the epicyclic angular frequency, and A(R) and B(R) are Oort's constants. At the radius where ω + mΩ(R) = 0 the pattern of the disturbance moves around at the same velocity as the circular motion of the stars epicentre. The other resonances that were discovered by B. Lindblad lie one within and one outside that circle.
Spiral waves caused by a passage of the LMC?
Authors: Toomre A.
Published: July 2016

This progress report on the deduction of an almost grazing orbit of the Large Magellanic Cloud from the warped shape of our Galaxy focused on two issues of special relevance to this Symposium:

(i)

Distance R0. - An implausibly large mass (> 3 × 1010M⊙) of the LMC is needed to account for the observed warp even with the most optimal orbit, using Schmidt's (1965) disk model of our Galaxy, or any close variant thereof. Although as yet only tentative, the inference seems to be that our distance R0 from the galactic center has been overestimated; instead of the now ‘standard’ R0 = 10 kpc, these disk-bending calculations suggest a value more like the older R0 ≅ 8 kpc.

(ii)

Forced spiral waves. - Even with the revised R0, the sense of the LMC orbit remains ambiguous (though not the perigalactic distance of roughly 20 kpc nor the low absolute inclination of that orbit relative to the galactic plane). Neither the detailed shapes of the vertically bent model disks, nor any computed tidal effects of the Galaxy upon the LMC and SMC, either separately or as a system, rule out an LMC passage that is retrograde with respect to the galactic rotation, but all favor a direct passage as being the more plausible. The latter kind of passage, however, presents an embarrassment of riches.
Numerical experiments in spiral structure
Authors: Miller R. H. , Prendergast K. H. , Quirk W. J.
Published: July 2016

Results of an n-body calculation, containing about 120000 particles, were shown as a motion picture. Some of the particles are treated as ‘gas’, obeying a special dissipative dynamics, the rest as ‘stars’. The system was started as pure ‘gas’, and ‘stars’ were made out of the ‘gas’ in a manner closely mimicking real galaxies. Spiral density wave patterns appear in the ‘gas’, and last for about 3 ‘galactic rotations’ without substantial change of form. Various experiments are described that have been undertaken in an attempt to learn the roles of various parts of the system in the maintenance of spiral patterns.
Large-scale galactic shock phenomena and the implications on star formation
Authors: Roberts W. W.
Published: July 2016

The possible existence of a stationary two-armed spiral shock pattern for a disk-shaped galaxy, such as our own Milky Way System, is demonstrated. It is therefore suggested that large-scale galactic shock phenomena may very well form the large-scale triggering mechanism for the gravitational collapse of gas clouds, leading to star formation along narrow spiral arcs within a two-armed grand design of spiral structure.
Deviation of the vertex of the velocity ellipse of young stars and its connection with spiral structure
Authors: Woolley Sir R.
Published: July 2016

The deviation of the vertex of the velocity ellipse of stars of spectral class A is shown clearly in a diagram published by Strömberg (1946); no such clear deviation is shown by the velocity ellipses of stars of other spectral types in his diagrams. This deviation of the vertex or tilt of the velocity ellipse can have some connexion with spiral structure, and there seem to be two possibilities, (a) that the tilt is confined to young stars only, and has something to do with an initial condition of their formation; and (b) that the tilt is a manifestation of the nature of the attracting field in the neighbourhood of the sun, which is not central on account of the attractions of spiral arms.

The present note examines data taken from the velocities of nearby stars, and uses the classification of the late type main sequence stars put forward by Wilson, based on observations of the reversals in the Ca+ H and K lines.

From this material it is concluded that the vertex deviation is confined to young stars, and that hypothesis (a) rather than hypothesis (b) is correct – or at least strongly indicated by available observations. The paper goes on to show that the deviation of the vertex can be explained by supposing that the stars were formed comparatively recently in a thin strip of the galaxy more or less at right angles to the direction of the galactic centre – in fact, in something like a spiral arm.
Summary and outlook
Authors: Bok B. J.
Published: July 2016

Our Symposium has truly been held in the spirit of IAU Commission 33. This Commission has traditionally provided the opportunity for optical and radio astronomers to meet with theorists interested in the dynamics of stellar systems. Our good relations with Commission 34 assure us that in our deliberations we shall not lose sight of the physical implications of our theoretical and observational developments. The past and present Presidents of Commission 33 are proud of the fact that they – and their Organizing Committees – took the initiative for holding this Symposium in Basel. We need not hide the fact that the plan to go to Basel came because many of us wished to honor Wilhelm Becker and his associates for the beautiful and basic researches they have done relating to the spiral structure of our Galaxy.
Searches for Binary Stars in Globular Clusters
Authors: Pryor C. , Fletcher J.M. , Hesser J.E. , McClure R.D. , Stetson P.B. , Richer H.B. , Fahlman G.G. , Ibata R.A. , Ivanans N.C. , Mandushev G. , Bell R.A. , Bolte M. , Bond H.E. , Harris W.E. , Vandenberg D.A. , Wood M.A.
Published: July 2016

Primordial binaries in globular clusters are important both because their properties are an integral part of the description of the stellar population and because they can strongly influence the dynamical evolution of the cluster (see Hut, this volume).
Combining Stellar Evolution and Stellar Dynamics
Authors: Eggleton Peter P.
Published: July 2016

There seem to me to be four approaches to the problem of computing the evolution of star clusters. Firstly, one might assume that our knowledge of the evolution of stars can be condensed into a subroutine that can be added to an N-body code. This subroutine would mainly have to give the radius and the time-dependent mass of a star as a function of its initial mass and its age. Secondly, standing this on its head, one might assume that our knowledge of N-body evolution can be condensed into a subroutine that can be added to a stellar evolution code. This subroutine would determine, probably in a Monte-Carlo fashion, whether the star had picked up, or lost, a binary companion, or whether the orbit of its companion was significantly changed; the probabilities would be determined by simple analytic approximations to the time-dependent distribution functions of stars (and binaries) of different masses and ages, and by interaction cross-sections as functions of density and ‘temperature’. Thirdly, if the computing power is available, one might more simply unite an N-body code with a Stellar Evolution (SE) code, and follow both the dynamics and the internal evolution simultaneously. Fourthly, we might hope at some stage to put together simple analytic approximations both from N-body and from SE studies, to develop a unified simple model. I venture to say that it is only the last stage, if it is attainable, that would entitle us to say that we ‘understand’ the evolution of stellar clusters. ‘Understanding’, I think, means that we can extract some essential wisdom from large numerical simulations, and apply it on the back of the proverbial envelope.
Gravitational Scattering Experiments
Authors: McMillan Stephen L. W.
Published: July 2016

We describe a fully automated gravitational scattering package capable of determining cross sections and reaction rates for binary-single-star scattering, and present some applications to systems of astrophysical interest.