bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil Dating By Fractional Extraction of Humic Acid
Authors: Kigoshi Kunihiko , Suzuki Nobuko , Shiraki Mari 
Published: July 2016

The addition of organic materials derived from the upper soil layer yields, for samples at greater depth, younger 14C dates than the date of deposition. To find a criterion for the contamination with younger carbon in a soil sample, we examined the radiocarbon concentrations in two humic acid fractions and humin taken from the same sample. The humic acid extracted from a soil sample was divided into two fractions HA1 and HA2. HA1 is the first fraction extracted by 30 minutes' heating with 2 percent NaOH solution, and HA2 is the second fraction extracted by 2 hours' heating with 2 percent NaOH solution after the extraction of HA1. The residue was assumed as the humin (HM).Many of the peat or soil samples taken from the layer just above the nonpermeable layer contain appreciable amounts of organic materials transported from the upper layer after the sedimentation of the deposits. For the limited number of cases tested here, there is a trend in which the contaminants are selectively extracted by HA1 or HA2. When the soil samples are contaminated the ages of the HA1 and HA2 fractions appeared to differ widely in most cases. Agreement between the HA1, HA2, and HM ages may be used as a criterion for the reliability of the soil dating.
Miami Natural Radiocarbon Measurements III
Authors: Rusnak Gene A. , Bowman Albert L. , ӧstlund H. Gӧte 
Published: July 2016

The list of dates grouped below is a continuation of work reported in our earlier lists. In one case (Core A 254-BR-C), an extensive sequence of dates is reported which, for completeness, includes some data presented in an earlier report (Miami II, 1963).We continue to use a 1.0-L CO2 proportional counter operating a 3 atm pressure (see Stockholm V for details). Except for the early incorporation of a counter for tritium analyses within our present shielding house and switching over to transistorized electronics, we do not anticipate changes in our set-up.Wherever possible we have entered the δC13 corrected date as well as the δC13 value determined from that sample. An apparent 400-yr sea-surface carbonate age is subtracted from the calculated age of marine carbonate materials, but not for organic material (Miami I and Miami II).
Birmingham University Radiocarbon Dates III
Authors: Shotton F. W. , Blundell D. J. , Williams R. E. G. 
Published: July 2016

Measurements have continued with the 6 L counter. A counter of similar design but with 1 L volume has recently been brought into operation. Despite replacement of the teflon parts, the 1.5 L Oeschger-type counter has not worked consistently and has not been used for dating. Results are not corrected for δ C13. Errors quoted refer only to the standard deviation calculated from a statistical analysis of count rates and the Libby half-life of 5570 ± 30 yr.Alkali pretreatment is used for all samples of charcoal, peat, wood, and plant material provided they are of sufficient quantity. It is now standard practice to boil the sample in 5% HCl solution and filter, both before and after boiling it in 2% NaOH solution. Between each treatment it is washed in boiling distilled water and is finally oven dried at 110°C. Concentrations of acid and alkalis are varied to suit each sample but the sequence of the pretreatment is always the same. In some cases a humate extract is obtained by precipitation with weak acid from the alkali solution filtrate.The collagen fraction is obtained from samples of bone using the method of Krueger (1966) by treatment with dilute acid under reduced pressure. The gas evolved during the treatment is usually discarded but is occasionally retained and dated as the mineral fraction.After mechanical cleaning, samples of shell are dissolved in stages with 6N HCl to divide them into two or three fractions corresponding to the outer, middle, and inner layers of the shell. Normally the outer fraction is discarded when three fractions have been prepared.
Gif Natural Radiocarbon Measurements III
Authors: Delibrias G. , Guillier M. T. , Labeyrie J. 
Published: July 2016

The dates detailed below are a selection of C14 dates obtained from February 1966 to December 1967 for geologic samples. The method is essentially the same as described previously in Radiocarbon, 1966, v. 8 p. 74-95. All samples were subjected to pretreatment, differing in individual cases, to remove contamination. On one of our three installations, modern transistorized equipment replaced the original electronics.All dates reported have been calculated on the assumed half-life of 5568 yr for C14, and of 1950 as the reference year.
New Radiocarbon Dates from the Balkans (Dubene-Sarovka): Approach to the Early Bronze Absolute Chronology in Upper Thrace
Authors: Nikolova Lolita , Görsdorf Jochen 
Published: July 2016

This paper addresses the absolute chronology of the earlier Yunatsite and Ezero cultures in Upper Thrace (South Bulgaria), from Early Bronze I and the beginning of Early Bronze II. The two newly obtained radiocarbon dates from Early Bronze Dubene-Sarovka (the Upper Stryama Valley) are published and discussed in a detailed stratigraphic and comparative Early Bronze I–Early Bronze II context. Date Bln-5233 (3490–3120 cal BC) is the first14C date from the Upper Maritsa valley from Early Bronze I with well-defined stratigraphic context and values earlier than 3100 BC. This date adds new arguments to the discussion of the14C dates from Yunatsite 15 and Plovdiv–Nebet Tepe, and addresses the question of the comparative chronology of Yunatsite I and Ezero I cultures from the late fourth millennium BC.The sample of the date Bln-5231 (2870–2620 cal BC) comes from a level on the border between Early Bronze I and Early Bronze II. On one hand, its values preceded the values of the earlier-obtained14C dates from IIB layer and confirmed the stratigraphic sequence at Dubene-Sarovka tell. On the other hand, the calibrated values seem to be later than the vast comparative chronology of the end of the Dubene IIA&Mdash;the beginning of Dubene IIB (ca. 3000 BC). Similar problems occur with dates from Yunatsite and Ezero. The published new dates from Dubene-Sarovka are part of the project on complex elaborating of the Early Bronze absolute chronology in the Balkans, and especially on contextual analysis of the14C dates.
Geological Survey of Canada Radiocarbon Dates II
Authors: Dyck W. , Fyles J. G. 
Published: July 2016

The accompanying date list includes age determinations completed during the period December 1, 1961 to November 1, 1962. All measurements were made with the 2 L counter described in our first date list (GSC I). Sample preparation, counting procedures, and calculation of dates were as described in GSC I except as outlined below:
a.Base and acid treatments were carried out with 1N HCl and 2% NaOH instead of 2N HCl and 4% NaOH, because the less-concentrated solutions were still strong enough to accomplish the desired purification.b.The Mg(C104)2 drying columns were removed from the purification train in order to test their effect, if any, on the purity of the gas. Since there was no detectable change in the purity of the gas these columns were left out of the purification line.c.Ages were calculated using 0.950 of the activity of the N.B.S. oxalic-acid standard as the reference activity and a.d. 1950 as the zero reference year, in line with the recommendations of the editors of Radiocarbon.
Measurement of Low 14C Activities in a Liquid Scintillation Counter in the Zagreb Radiocarbon Laboratory
Authors: Horvatinčić Nada , Barešić Jadranka , Krajcar Bronić Ines , Obelić Bogomil 
Published: July 2016

Two methods of chemical preparation of radiocarbon samples are implemented in the Zagreb Radiocarbon Laboratory for measurement by a new liquid scintillation counter (LSC), Quantulus 1220™: a CO2 absorption method (LSC-A) and a benzene synthesis method (LSC-B). For samples prepared by both methods, the optimal counting windows for measurement in LSC were determined. The total efficiency of LSC-A is 65% and that of the LSC-B is 83%, while the corresponding 14C dating limits are 31,800 yr and 52,160 yr, respectively.14C activities measured by the LSC-A and LSC-B methods were compared with those measured by the gas proportional counter (GPC) method (efficiency 75%, 14C dating limit 37,500 yr). The results obtained by the LSC-A method have larger errors than those measured by the GPC method, but LSC-A is quick, inexpensive, simple, and requires less carbon than the GPC method. Thus, LSC-A is suitable for 14C measurements of geological, hydrological, and environmental samples. On the other hand, the results obtained by the LSC-B method give smaller errors and a larger 14C dating range. Therefore, LSC-B is more suitable for 14C dating of archaeological samples.
HBCO Correction: Its Impact on Archaeological Absolute Dating
Authors: Barta Peter , Štolc Svorad 
Published: July 2016

When constructing absolute chronologies in archaeology, the aim is to detect archaeological events. In this respect, we draw attention to the relation between the radiocarbon ages of human bone collagen samples and the absolute dating evidence on the age at death. In recent material, Mebus Geyh (2001a,b) described the offset between the former and the latter, and suggested the relevant correction. The corrected 14C ages pertain to the age of the individual at death.We have developed an application of Geyh's original observation, which we term the human bone collagen offset (HBCO) correction, to apply to archaeological 14C dates. If the death and interment of individuals are identical, the corrected 14C date reliably informs us about the deposition of the body and accompanying grave goods. In archaeology, the concrete correction value is determined by the anthropologically estimated age of the individual, which we model by a normal (Gaussian) distribution. The eventual impact of the HBCO correction on archaeological chronology depends on the portion of the calibration curve through which the HBCO-corrected date is calibrated. At a certain level of 14C measurement precision, the difference between the HBCO-corrected and non-corrected calendar dates can be considerable.
Letter to the Editor
Authors: Gove H. E. 
Published: July 2016

Dear Editor,Professor R. E. Taylor, in his review for R adiocarbon of my book Relic, Icon or Hoax? Carbon Dating the Turin Shroud (Taylor 1997) noted that I had incorrectly used the word “invent” and its derivatives in connection with the origins of accelerator mass spectrometry (AMS). A more accurate description of the development of AMS is to be found in the papers that I co-authored (Gove, Litherland and Purser 1987) and authored (Gove 1992) prior to publication of my book. Who actually “invented” AMS is not clear. Certainly, strong contenders are L. W. Alvarez and R. Cornog (Alvarez and Cornog 1939) and K. H. Purser (Purser 1977). The contributions made by Purser, A. E. Litherland and me to the development of AMS were recognized by Pergamon Press in 1980 when the Board of Editors of the International Journal of Applied Radiation and Isotopes (JARI) voted to give us the first JARI award. I should note that neither of my two colleagues with whom I was involved in the development of AMS, Professor Litherland nor Dr. Purser, saw a copy of my book before publication. If they had, this unintended contretemps would not have occurred.Yours sincerely,
Density distribution and the radial velocity field in the spiral arms of M31
Authors: Einasto J. , Rümmel U. 
Published: July 2016

The density distribution and the radial velocity field in the Andromeda galaxy, M 31, have been studied on the basis of the 21-cm radio-line data from Jodrell Bank and Green Bank. The true density has been obtained from the observed one by solving a two-dimensional integral equation. As the resolving power of the radio telescopes is too low to locate all spiral arms separately, optical data on the distribution of ionized hydrogen clouds have been also used. The mean radial velocities have been derived by solving a two-dimensional non-linear integral equation with the help of hydrogen densities, and a model radial velocity field.The inner concentrations of hydrogen form two patchy ringlike structures with mean radii 30′ and 50′, the outer concentrations can be represented as fragments of two leading spiral arms.The rotational velocity, derived from the radial velocity field, in the central region differs considerably from the velocity curves obtained by earlier authors. The difference can be explained by the fact that in this region the correction for the antenna beam width is much greater than adopted by previous investigators.
Pulsars in Globular Clusters
Authors: Kulkarni S. R. , Anderson S. B. 
Published: July 2016

Since the discovery of the first globular cluster pulsar in M28 (Lyne et al. 1987) a total of 33 pulsars have been found to reside within 13 seperate clusters. Many (but not all) of the cluster pulsars have properties similar to the millisecond pulsars in the disk: short period, binarity and low magnetic field strength. The common understanding is that these pulsars are primordial neutron stars (i.e. the remnants of massive stars in clusters) which have been spun up by accretion of matter from a companion. Therefore, in this framework, the cluster pulsars are descendents of Low Mass X-ray Binaries (LMXBs) (Alpar et al. 1982). This hypothesis is by no means accepted by all workers (e.g. Michel 1987, Ray & Kluzniak 1990, Romani 1990, Bailyn & Grindlay 1993). These workers have argued that at least some (if not all) cluster pulsars could be formed by accretion induced collapse of massive white dwarfs. In either case, it is clear from the sensitivity limits of current cluster searches, and the luminosity of field pulsars, that there are currently O(103) extant radio pulsars in the Galactic globular cluster system.In this review, specifically targeted for astronomers working in the field of globular clusters, not pulsar astronomers, we argue that cluster pulsars have provided us with a new window into the population of long-dead massive stars and the physics of tidal capture. The precision with which pulsars can be timed has created new diagnostics: measurement of the mass distribution in the dense cores, measurement of orbital evolution on short timescales and precise determination of orbital characteristics. It is fair to say that all these diagnostics are unique, and not obtainable by other observations. Despite this, it is our assessment that the typical astronomer who works in the field of globular clusters is apparently unaware of these relevant contributions. Hopefully this review will bridge this gap. A complete copy of the review article may be found at http://astro.caltech.edu/~srk.
A Study of the Continua of the Nuclei of Galaxies
Authors: Alloin D. , Andrillat Y. , Souffrin S. 
Published: July 2016

Many people have attacked the problem of synthesizing the stellar population of the galaxies. We have performed such a synthesis, by using only the intensities of absorption lines in the nuclei of galaxies. It is then possible to obtain a synthesized continuous spectrum even if there are several possible solutions for the stellar composition, and the computed continuum does not vary much with the assumed model of stellar population.The method is to fit the equivalent widths of the absorption lines using different stellar compositions. In order to avoid any instrumental effect, we have observed different lines and bands from 3500 to 8500 å in stars of various well-known stellar types and luminosity classes, under the same conditions as the galaxies.We have applied this method to some ‘ordinary’ nuclei and to some Seyfert ones. As an example, we show the results for M81 and for NGC 1068.
Matter-Antimatter Annihilation as an Energy Source in Seyfert Galaxies
Authors: Steigman G. , Strittmatter P. A. 
Published: July 2016

The extreme infrared luminosities of some Seyfert galaxies place severe requirements on the efficiency of the energy source. It is attractive to suggest that matter-antimatter annihilation supplies the necessary energy source; efficiencies of up to ∼50% are, in principle, obtainable. However, there is a price to pay for such an explanation: gamma rays and neutrinos.In a typical nucleon-antinucleon annihilation roughly ⅓ Mc2 is released in electron-positron pairs, ∼⅔ Mc2 in ∼3 gamma rays and ∼Mc2 in ∼3 electron-neutrinos and ∼6 muon-neutrinos. As a result, if the observed infra-red power is to be derived from the energy in electron-positron pairs, then the flux of gamma rays would be 102-103 times the upper limits to the gamma ray flux. It is, of course, possible to account for the absence of the gamma rays by insisting that they be absorbed in the source. The neutrinos, however, will not be stopped and hence provide the possibility of testing the annihilation hypothesis.We have computed the spectrum of neutrinos produced in annihilation. Assuming the product of the space density and infrared luminosity of Seyfert galaxies varies with redshift (z) as: L (z) n (z) = L0n0 (1 + z)m we have computed the flux of μ-neutrinos contributed by all Seyfert galaxies out to a given red-shift for m = 3 and m = 6.5 (strong evolution). Further, assuming the “3K” and “0.3 mm” background radiation fields to be caused by a burst of “Seyfert type” objects at appropriate redshifts, we have again computed the expected μ-neutrino flux. When these results are compared with present limits on the flux of μ-neutrinos at the Earth, as determined from experiments performed by several groups deep underground, it emerges that the predicted flux is comparable to or greater than present upper limits. Thus, annihilation probably does not supply the infrared sources in Seyfert galaxies with the energy they require.
Transient Annular Structures in Exploding Galaxies
Authors: Sěrsic J. L. 
Published: July 2016

The explosive events going on in the central parts of some galaxies are related to a very high mass concentration. As an explosion is actually a drastic rearrangement of the concerned masses with energy release, the binding energy of the central core will change and, correspondingly, its effective gravitational mass. A test particle far from the nuclear region, although within the galaxy, will be moving accordingly in a variable-mass Newtonian gravitational field.On the other hand the observations suggest that explosions in galaxies have axial symmetry, so we are concerned with the global properties of the motion of a particle in a variable mass axisymmetric gravitational field. In order to get rid of the mass variation a space-time conformal transformation is made, which, after imposing some not very restrictive conditions, leads to a conservative potential in the new variables. This new potential has additional terms due to the elimination of the variable mass. The equations of motion in the new variables provide the motion of the test particle relative to an expanding or contracting background which depends on the choice of the transformation and the law of the mass variability. The problem is, at this point, formally similar to Hill's. It is possible to write an equation for the relative energy (a generalization of Jacobi's integral) and also to define surfaces of zero relative velocity for the infinitesimal particle. The general topological properties of these surfaces require singular points along the symmetry axis (analogous to the collinear Eulerian points) and also a dense set in a circumference on a plane perpendicular to the symmetry axis (analogous to the Lagrangian points). The latter one is the main feature characterizing the topology of the zero relative velocity surfaces. Even when we lift some of the restrictive conditions, the Lagrangian ring preserves its properties, as for example, the one of being the only region where zero-velocity curves and equi-potentials coincide when the configuration evolves in time (in the transformed space-time).It is easy to understand that the topology of the surfaces is kept when we reverse the transformation and go back to physical space-time. If the dust, gas or stars in the system has definite upper limits for its Jacobian constants, spatial segregation of them will arise, as is the case in radio-galaxies such as NGC 5128, NGC 1316, etc. where ringlike dust structures are observed.
Two-Dimensional Stochastic Motions and the Problem of Differential Rotation for Unrestricted Rotational Rates
Authors: Rüdiger G. 
Published: July 2016

For dealing analytically with the problem of differential rotation we investigate the spatial dependence of the angular velocity in a rotating turbulent fluid. The original turbulence unaffected by the rotation is assumed to be two-dimensional, where the stochastic motions completely lie in the horizontal planes. From the expression describing the relation between the correlations of rotating and nonrotating turbulent fields the meridional flux of momentum is derived. The resulting rotational law is determined by using Bochner's theorem for homogeneous turbulence as well as the characteristic scales of the turbulence field considered. The conclusions are:
(a)The angular velocity ω is increasing toward the outer layers.(b)For 2 Ω ≪ ωc (ωc frequency of turbulent mode) the Biermann-Kippenhahntheory of anisotropic viscosity is deduced. An equatorial acceleration is only caused by a meridional circulation.(c)For 2 Ω ≲ ωc a latitudinal dependence of ω is possible without any meridional circulation. If the two-dimensional eddy viscosity is negative the equatorial regions are accelerated. The expression for the two-dimensional eddy viscosity which has been derived earlier allows negativity in contrast to that for three-dimensional eddy viscosity. The scale length and the scale time of supergranulation as well as of giant cells lead to negative two-dimensional eddy viscosity.
Influence of Abundances Upon Stellar Atmosphere Calculations
Authors: Baschek B. 
Published: July 2016

The basic equations for constructing a stellar atmosphere (hydrostatic equilibrium, flux constancy, radiative transfer, convective instability) are briefly summarized. While the parameters Teff (effective temperature) and g (surface gravity) are directly contained in these equations, the element abundances ∈i enter only indirectly through the thermodynamic properties (such as electron pressure, entropy, …) and the absorption and scattering coefficients of stellar matter.The equation of state, convection, the effects of the absorption coefficients (particularly of line absorption) on the temperature stratification, and the role of velocity fields (microturbulence) are discussed in some detail, emphasizing their dependence on the abundances.From a given model atmosphere, a ‘theoretical spectrum’ (colours, bolometric correction, line strengths etc.) can be calculated. The (relative) fluxes emerging at the surface are essentially determined by the temperature gradient and the absorption coefficients at the frequencies under consideration. The basic goal of quantitative classification, however, is the inverse problem, namely to deduce the stellar parameters from selected observed spectral criteria. Aspects relevant to this problem such as the question of uniqueness and the occurrence of possible systematic errors (even when using differential analysis techniques) are briefly sketched and illustrated by some examples.