scholarly journals Fractionation Corrections in Radiocarbon Dating

Radiocarbon ◽  
1981 ◽  
Vol 23 (2) ◽  
pp. 173-190 ◽  
Author(s):  
T M L Wigley ◽  
A B Muller
Keyword(s):  
Theoretical Analysis ◽  
Experimental Work ◽  
Radiocarbon Dating ◽  
Published Data ◽  
Radiocarbon Dates ◽  
B Values ◽  
Radiocarbon Age ◽  
The Difference ◽  
Image Position ◽  
Recent Experimental Work

Recent experimental work has suggested that the relative fractionation of 14C to 13C may differ from the accepted value of b = 2. In order to explore the implications of this possibility, the standard formulae for correcting radiocarbon dates for fractionation effects are rederived, but without making any of the usual assumptions or approximations. A generalized dating equation is derived (where ASN and AON are normalized sample and standard activities, β is a factor which reflects changes in atmospheric 13C and 14C content, {RST(o)/RST}b accounts for post-depositional changes in sample 13C ratio, and tcal is calendar age in years before ad 1950. The errors in calculated ages which might arise from different b values are estimated and shown to be small relative to other dating uncertainties. The effect of b ≠ 2 may be important in the calibration of radiocarbon dates using tree-ring samples of known age. A theoretical analysis suggests that b ≠ 2 effects may result in a correlation between age anomaly (ie, the difference between radiocarbon age and calendar age) and sample 13C data. However, an analysis of published data reveals no meaningful correlation. This result, while not eliminating the possibility that b ≠ 2, highlights its unimportance even in this high-precision application of radiocarbon dating.

Determination of the Age of Swiss Lake Dwellings as an Example of Dendrochronologically-Calibrated Radiocarbon Dating

1966 ◽  
Vol 21 (7) ◽  
pp. 1173-1177 ◽  
Author(s):  
C. W. Ferguson ◽  
B. huber ◽  
H. E. Suess
Keyword(s):  
Tree Ring ◽  
Standard Error ◽  
Radiocarbon Dating ◽  
Tree Ring Chronology ◽  
Radiocarbon Dates ◽  
Pine Wood ◽  
Bristlecone Pine ◽  
The Difference ◽  
Swiss Lake

Comparison of the radiocarbon content of a series of samples of dendrochronologically dated bristlecone pine wood with that from trees for which a so-called floating tree-ring chronology has been established makes it possible to determine an empirical age for this floating tree-ring series based upon the age of the wood used for comparison. For the case of the Swiss Lake Dwellers, the difference between conventional radiocarbon dates and the age values determined in this manner amounts to about 800 years. The age of the floating chronology was determined within a standard error of less than 40 years. The measurements indicate that the dwellings were constructed during the 38th century B. C.

scholarly journals Discourse coherence and the interpretation of accented pronouns

2017 ◽  
Vol 8 (2) ◽  
pp. 84-104
Author(s):  
Mindaugas Mozuraitis ◽  
Daphna Heller
Keyword(s):  
Experimental Work ◽  
Alternative Interpretation ◽  
Minimal Change ◽  
Comprehension Task ◽  
Discourse Coherence ◽  
Coherence Relations ◽  
The Difference ◽  
Recent Experimental Work

It has long been argued that accenting or stressing a pronoun (i.e., making it prosodically prominent) changes its interpretation as compared to its unaccented counterpart. However, recent experimental work demonstrated that this generalization does not apply when the alternative interpretation of the pronoun is not plausible (Taylor et al., 2013). In a series of three experiments that use an offline comprehension task, we show, first, that the lack of reversal is observed when plausibility is controlled for. We furthermore show that a new generalization cannot be formed by excluding cases where the bias towards the unmarked interpretation is strong or cases where the character in the alternative interpretation is low in salience. Instead, we conclude that what constrains the interpretation of accented pronouns is coherence relations, with parallel discourses exhibiting reversal and result discourses not exhibiting reversal. We propose that the difference between coherence relations should be viewed in what would be the minimal change in order to create a ‘surprising’ or expected’ event, which is the characteristic of accenting more generally.

Radiocarbon dates of snow petrel (Pagodroma nivea) nest sites in central Dronning Maud Land, Antarctica

Polar Record ◽  
1997 ◽  
Vol 33 (184) ◽  
pp. 29-38 ◽  
Author(s):  
W.K. Steele ◽  
A. Hiller
Keyword(s):  
Radiocarbon Dating ◽  
Last Glacial Period ◽  
Radiocarbon Dates ◽  
Radiocarbon Age ◽  
Clear Cut ◽  
Nest Sites ◽  
Snow Petrel ◽  
Dronning Maud Land ◽  
Nesting Activity ◽  
The Last Glacial

AbstractThis paper presents the results of a radiocarbon dating study of snow petrel (Pagodroma nivea) nest sites in central Dronning Maud Land, Antarctica. Mumiyo (a sub-fossilized accumulation of regurgitated proventricular oil) samples were collected from 15 snow petrel nest sites at nunataks in the northern Ahlmannryggen, Gjelsvikfjella, and Mühlig-Hofmannfjella.Radiocarbon dating revealed Holocene ages of ca 8500 years and less for all but one of these mumiyo samples. A sample collected at S varthamaren in the Muhlig-Hofmannfjella was dated as old as ca 34,000 a BP, indicating that at least some areas of that mountain escaped the scouring action of glaciers during the last glacial period. Similar pre-Holocene ages have been determined for a small number of mumiyo samples in previous studies. Mumiyo accumulations from some nests indicate periods of occupation as long as 6000 years, whereas the radiocarbon age and volume of other mumiyo samples suggest short periods of frequent nesting activity. As expected, sub-samples extracted from the lower layers of mumiyo pieces generally displayed greater ages than sub-samples from upper layers of the same piece. However, there was no clear-cut correlation between the age of a mumiyo sample and its height above the present ice level. It is suspected that this lack of correlation is due to some of the mumiyo samples being displaced previously through rockfalls.

scholarly journals High-Precision Bidecadal Calibration of the Radiocarbon Time Scale, AD 1950–500 BC and 2500–6000 BC

Radiocarbon ◽  
1993 ◽  
Vol 35 (1) ◽  
pp. 1-23 ◽  
Author(s):  
Minze Stuiver ◽  
Gordon W. Pearson
Keyword(s):  
Pacific Northwest ◽  
High Precision ◽  
Calibration Curve ◽  
Time Scale ◽  
Published Data ◽  
Data Sets ◽  
Radiocarbon Dates ◽  
Radiocarbon Age ◽  
The Us ◽  
Bristlecone Pine

The radiocarbon ages of dendrochronologically dated wood spanning the AD 1950–6000 BC interval are now available for Seattle (10-yr samples, Stuiver & Becker 1993) and Belfast (20-yr samples, Pearson, Becker & Qua 1993; Pearson & Qua 1993). The results of both laboratories were previously combined to generate a bidecadal calibration curve spanning nearly 4500 years (Stuiver & Pearson 1986; Pearson & Stuiver 1986). We now find that minor corrections must be applied to the published data sets, and therefore, give new bidecadal radiocarbon age information for 2500–6000 BC, as well as corrected radiocarbon age averages for AD 1950–500 BC. Corrected average 14C ages for the 500–2500 BC interval are given separately (Pearson & Stuiver 1993). The Seattle corrections (in the 10–30 14C-yr range) are discussed in Stuiver and Becker (1993), whereas Pearson and Qua (1993) provide information on Belfast corrections (averaging 16 yr). All dates reported here are conventional radiocarbon dates, as defined in Stuiver and Polach (1977). Belfast 14C ages back to 5210 BC were obtained on wood from the Irish oak chronology (Pearson et al. 1986). Wood from the German oak chronology (Becker 1993) was used by Belfast for the 5000–6000 BC interval. For the overlapping interval (5000–5210 BC), Belfast reports weighted Irish wood/German wood 14C age averages. The Seattle 14C ages for the AD interval were either on Douglas fir wood from the US Pacific Northwest, or Sequoia wood from California (Stuiver 1982). The BC materials measured in Seattle were mostly part of the German oak chronology. Thirteen samples (5680–5810 BC) from the US bristlecone pine chronology (Ferguson & Graybill 1983) were measured in Seattle as well. Here, the final Seattle decadal 14C ages resulted from averaging German oak and bristlecone pine ages.

The role of differential phase contrast in electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 176-177
Author(s):  
E.M. Waddell ◽  
J.N. Chapman ◽  
R.P. Ferrier
Keyword(s):  
Phase Contrast ◽  
Practical Method ◽  
Position Vector ◽  
Differential Phase ◽  
Pure Phase ◽  
Differential Phase Contrast ◽  
The Difference ◽  
Image Position ◽  
First Moment

Dekkers and de Lang (1977) have discussed a practical method of realising differential phase contrast in a STEM. The method involves taking the difference signal from two semi-circular detectors placed symmetrically about the optic axis and subtending the same angle (2α) at the specimen as that of the cone of illumination. Such a system, or an obvious generalisation of it, namely a quadrant detector, has the characteristic of responding to the gradient of the phase of the specimen transmittance. In this paper we shall compare the performance of this type of system with that of a first moment detector (Waddell et al.1977).For a first moment detector the response function R(k) is of the form R(k) = ck where c is a constant, k is a position vector in the detector plane and the vector nature of R(k)indicates that two signals are produced. This type of system would produce an image signal given bywhere the specimen transmittance is given by a (r) exp (iϕ (r), r is a position vector in object space, ro the position of the probe, ⊛ represents a convolution integral and it has been assumed that we have a coherent probe, with a complex disturbance of the form b(r-ro) exp (iζ (r-ro)). Thus the image signal for a pure phase object imaged in a STEM using a first moment detector is b2 ⊛ ▽ø. Note that this puts no restrictions on the magnitude of the variation of the phase function, but does assume an infinite detector.

Kinematical and Dynamical CBED Pattern Models: Increasing the Accuracy of the Unit-Cell Parameter Measurements Based on CBED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 540-541
Author(s):  
I.N. Yadhikov ◽  
S.K. Maksimov
Keyword(s):  
Reciprocal Lattice ◽  
Unit Cell ◽  
Reciprocal Lattice Vector ◽  
Unit Cell Parameters ◽  
Lattice Vector ◽  
Cell Parameters ◽  
Accuracy Of Measurements ◽  
The Difference ◽  
Image Position ◽  
Convergent Beam

Convergent beam electron diffraction (CBED) is widely used as a microanalysis tool. By the relative position of HOLZ-lines (Higher Order Laue Zone) in CBED-patterns one can determine the unit cell parameters with a high accuracy up to 0.1%. For this purpose, maps of HOLZ-lines are simulated with the help of a computer so that the best matching of maps with experimental CBED-pattern should be reached. In maps, HOLZ-lines are approximated, as a rule, by straight lines. The actual HOLZ-lines, however, are different from the straights. If we decrease accelerating voltage, the difference is increased and, thus, the accuracy of the unit cell parameters determination by the method becomes lower.To improve the accuracy of measurements it is necessary to give up the HOLZ-lines substitution by the straights. According to the kinematical theory a HOLZ-line is merely a fragment of ellipse arc described by the parametric equationwith arc corresponding to change of β parameter from -90° to +90°, wherevector, h - the distance between Laue zones, g - the value of the reciprocal lattice vector, g‖ - the value of the reciprocal lattice vector projection on zero Laue zone.

A quantitative evaluation of some factors affecting the non-fatty solids of cow's milk

1960 ◽  
Vol 27 (1) ◽  
pp. 19-32 ◽  
Author(s):  
W. H. Alexander ◽  
F. B. Leech
Keyword(s):  
Cell Count ◽  
Residual Effect ◽  
Clinical Mastitis ◽  
High Cell ◽  
Factors Affecting ◽  
Stage Of Lactation ◽  
Cell Counts ◽  
Satisfactory Analysis ◽  
The Difference ◽  
Image Position

SummaryTen farms in the county of Durham took part in a field study of the effects of feeding and of udder disease on the level of non-fatty solids (s.n.f.) in milk. Statistical analysis of the resulting data showed that age, pregnancy, season of the year, and total cell count affected the percentage of s.n.f. and that these effects were additive and independent of each other. No effect associated with nutritional changes could be demonstrated.The principal effects of the factors, each one freed from effects of other factors, were as follows:Herds in which s.n.f. had been consistently low over a period of years were compared with herds in which s.n.f. had been satisfactory. Analysis of the data showed that about 70% of the difference in s.n.f. between these groups could be accounted for by differences in age of cow, stage of lactation, cell count and breed.There was some evidence of a residual effect following clinical mastitis that could not be accounted for by residual high cell counts.The within-cow regression of s.n.f. on log cell count calculated from the Durham data and from van Rensburg's data was on both occasions negative.The implications of these findings are discussed, particularly in relation to advisory work.

scholarly journals ON PROPERTIES OF FINITE-ORDER MEROMORPHIC SOLUTIONS OF A CERTAIN DIFFERENCE PAINLEVÉ I EQUATION

2011 ◽  
Vol 85 (3) ◽  
pp. 463-475 ◽  
Author(s):  
MEI-RU CHEN ◽  
ZONG-XUAN CHEN
Keyword(s):  
Finite Order ◽  
Meromorphic Solutions ◽  
Rational Solutions ◽  
Polynomial Solutions ◽  
The Difference ◽  
Image Position

AbstractIn this paper, we investigate properties of finite-order transcendental meromorphic solutions, rational solutions and polynomial solutions of the difference Painlevé I equation where a, b and c are constants, ∣a∣+∣b∣≠0.

Merciful heavens? A question in Aeschylus' Agamemnon

1974 ◽  
Vol 94 ◽  
pp. 100-113 ◽  
Author(s):  
Maurice Pope
Keyword(s):  
Oral Tradition ◽  
Correct Reading ◽  
The Difference ◽  
Image Position

In discussions of Aeschylus' theology one of the passages most often quoted is the so-called ‘hymn to Zeus’ in the first chorus of the Agamemnon (Ag. 160–83). Fraenkel in his commentary goes so far as to call it ‘the corner-stone not only of this play but of the whole trilogy’. The passage concludes with two lines which in all modern editions are read as a statement, though our oldest manuscript, the Medicean, writes them as a question. Textually the difference is merely one of accent, but the difference of accent carries with it a reversal of meaning. As a statement the lines mean that the gods are something to be grateful for, that there is some χάρις or kindness associated with them. Taken as a question they deny this. Clearly then it is of great importance for the interpretation of Aeschylus to decide which is the correct reading.The lines in question, written without accents, areOur oldest manuscript, M, as I have said, writes ποῦ with an accent. So does our next oldest, the manuscript 468 of the Biblioteca di San Marco, generally known as V. If this reading stems uncorrupted from the time when accents were first applied to the text of Aeschylus and if at that time the oral tradition of the poet's words was not yet dead, then it will not be destitute of authority. But the thread is far too tenuous to bear any weight of proof.Equally there can be no argument from authority on the side of reading the lines as a statement. For though Triclinius and the closely associated manuscript F write που without an accent as an enclitic, this is as likely as not to be due to simple conjecture.

Determination of Resistance to Abrasive Wear. VIII. Influence of Softeners in Tests with the Akron-Croydon and Du Pont Machines

1949 ◽  
Vol 22 (1) ◽  
pp. 259-262
Author(s):  
J. F. Morley
Keyword(s):  
Unit Area ◽  
Published Data ◽  
The Road ◽  
Abrasive Surface ◽  
Abrasive Power ◽  
The Difference ◽  
On The Road ◽  
The Right ◽  
Abrasion Testing

Abstract These experiments indicate that softeners can influence abrasion resistance, as measured by laboratory machines, in some manner other than by altering the stress-strain properties of the rubber. One possible explanation is that the softener acts as a lubricant to the abrasive surface. Since this surface, in laboratory abrasion-testing machines, is relatively small, and comes repeatedly into contact with the rubber under test, it seems possible that it may become coated with a thin layer of softener that reduces its abrasive power. It would be interesting in this connection to try an abrasive machine in which a long continuous strip of abrasive material was used, no part of it being used more than once, so as to eliminate or minimize this lubricating effect. The fact that the effect of the softener is more pronounced on the du Pont than on the Akron-Croydon machine lends support to the lubrication hypothesis, because on the former machine the rate of wear per unit area of abrasive is much greater. Thus in the present tests the volume of rubber abraded per hr. per sq. cm. of abrasive surface ranges from 0.03 to 0.11 cc. on the du Pont machine and from 0.0035 to 0.0045 cc. on the Akron-Croydon machine. On the other hand, if the softener acts as a lubricant, it would be expected to reduce considerably the friction between the abrasive and the rubber and hence the energy used in dragging the rubber over the abrasive surface. The energy figures given in the right-hand columns of Tables 1 and 3, however, show that there is relatively little variation between the different rubbers. As a test of the lubrication hypothesis, it would be of interest to vary the conditions of test so that approximately the same amount of rubber per unit area of abrasive is abraded in a given time on both machines; this should show whether the phenomena observed under the present test conditions are due solely to the difference in rate of wear or to an inherent difference in the type of wear on the two machines. This could most conveniently be done by considerably reducing the load on the du Pont machine. In the original work on this machine the load was standardized at 8 pounds, but no figures are quoted to show how abrasion loss varies with the load. As an addition to the present investigation, it is proposed to examine the effect of this variation with special reference to rubbers containing various amounts and types of softener. Published data on the influence of softeners on the road wear of tire rubbers do not indicate anything like such large effects as are shown by the du Pont machine. This throws some doubt on the value of this machine for testing tire tread rubbers, a conclusion which is confirmed by information obtained from other workers.

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