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

Radiocarbon ◽  
1993 ◽  
Vol 35 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Gordon W. Pearson ◽  
Minze Stuiver
Keyword(s):  
High Precision ◽  
Time Scale ◽  
Count Rate ◽  
Basic Information ◽  
Data Set ◽  
Sole Purpose ◽  
Radon Decay

The sole purpose of this paper is to present a previously published 14C data set to which minor corrections have been applied. All basic information previously given is still applicable (Pearson & Stuiver 1986). The corrections are needed because 14C count-rate influences (radon decay in Seattle, a re-evaluation of the corrections applied for efficiency variation with time previously unrecognized in Belfast) had to be accounted for in more detail. Information on the radon correction is given in Stuiver and Becker (1993). The Belfast corrections were necessary because the original correction for efficiency variations with time was calculated using two suspect standards (these were shown to be suspect by recent observations) that overweighted the correction. A re-evaluation (Pearson & Qua 1993) now shows it to be almost insignificant, and the corrected dates (using the new correction) became older by about 16 years.

scholarly journals Calibration of the Radiocarbon Time Scale for the Southern Hemisphere: Ad 1850–950

Radiocarbon ◽  
2002 ◽  
Vol 44 (3) ◽  
pp. 641-651 ◽  
Author(s):  
F G McCormac ◽  
P J Reimer ◽  
A G Hogg ◽  
T F G Higham ◽  
M G L Baillie ◽  
...  
Keyword(s):  
South Africa ◽  
New Zealand ◽  
Southern Hemisphere ◽  
High Precision ◽  
Time Scale ◽  
Calibration Data ◽  
Data Set ◽  
Calibration Data Set ◽  
Consequent Effect

We have conducted a series of radiocarbon measurements on decadal samples of dendrochronologically dated wood from both hemispheres, spanning 1000 years (McCormac et al. 1998; Hogg et al. this issue). Using the data presented in Hogg et al., we show that during the period AD 950–1850 the 14C offset between the hemispheres is not constant, but varies periodically (∼130 yr periodicity) with amplitudes varying between 1 and 10% (i.e. 8–80 yr), with a consequent effect on the 14C calibration of material from the Southern Hemisphere. A large increase in the offset occurs between AD 1245 and 1355. In this paper, we present a Southern Hemisphere high-precision calibration data set (SHCal02) that comprises measurements from New Zealand, Chile, and South Africa. This data, and a new value of 41 ± 14 yr for correction of the IntCal98 data for the period outside the range given here, is proposed for use in calibrating Southern Hemisphere 14C dates.

scholarly journals Curating GitHub for engineered software projects

2016 ◽  
Author(s):  
Nuthan Munaiah ◽  
Steven Kroh ◽  
Craig Cabrey ◽  
Meiyappan Nagappan
Keyword(s):  
Software Engineering ◽  
High Precision ◽  
Ground Truth ◽  
Software Project ◽  
Software Projects ◽  
Data Set ◽  
High Recall ◽  
Home Work ◽  
Reference Implementation ◽  
Engineering Practices

Software forges like GitHub host millions of repositories. Software engineering researchers have been able to take advantage of such a large corpora of potential study subjects with the help of tools like GHTorrent and Boa. However, the simplicity in querying comes with a caveat: there are limited means of separating the signal (e.g. repositories containing engineered software projects) from the noise (e.g. repositories containing home work assignments). The proportion of noise in a random sample of repositories could skew the study and may lead to researchers reaching unrealistic, potentially inaccurate, conclusions. We argue that it is imperative to have the ability to sieve out the noise in such large repository forges. We propose a framework, and present a reference implementation of the framework as a tool called reaper, to enable researchers to select GitHub repositories that contain evidence of an engineered software project. We identify software engineering practices (called dimensions) and propose means for validating their existence in a GitHub repository. We used reaper to measure the dimensions of 1,994,977 GitHub repositories. We then used the data set train classifiers capable of predicting if a given GitHub repository contains an engineered software project. The performance of the classifiers was evaluated using a set of 200 repositories with known ground truth classification. We also compared the performance of the classifiers to other approaches to classification (e.g. number of GitHub Stargazers) and found our classifiers to outperform existing approaches. We found stargazers-based classifier to exhibit high precision (96%) but an inversely proportional recall (27%). On the other hand, our best classifier exhibited a high precision (82%) and a high recall (83%). The stargazer-based criteria offers precision but fails to recall a significant potion of the population.

scholarly journals Considerations for atmospheric retrieval of high-precision brown dwarf spectra

2020 ◽  
Vol 497 (4) ◽  
pp. 5136-5154
Author(s):  
Anjali A A Piette ◽  
Nikku Madhusudhan
Keyword(s):  
High Precision ◽  
Thermal Emission ◽  
Simulated Data ◽  
Brown Dwarfs ◽  
High Signal ◽  
Temperature Structure ◽  
Wide Field ◽  
Brown Dwarf ◽  
Data Set ◽  
Stellar Objects

ABSTRACT Isolated brown dwarfs provide remarkable laboratories for understanding atmospheric physics in the low-irradiation regime, and can be observed more precisely than exoplanets. As such, they provide a glimpse into the future of high-signal-to-noise ratio (SNR) observations of exoplanets. In this work, we investigate several new considerations that are important for atmospheric retrievals of high-quality thermal emission spectra of sub-stellar objects. We pursue this using an adaptation of the h y dra atmospheric retrieval code. We propose a parametric pressure–temperature (P–T) profile for brown dwarfs consisting of multiple atmospheric layers, parametrized by the temperature change across each layer. This model allows the steep temperature gradient of brown dwarf atmospheres to be accurately retrieved while avoiding commonly encountered numerical artefacts. The P–T model is especially flexible in the photosphere, which can reach a few tens of bar for T-dwarfs. We demonstrate an approach to include model uncertainties in the retrieval, focusing on uncertainties introduced by finite spectral and vertical resolution in the atmospheric model used for retrieval (∼8 per cent in the present case). We validate our retrieval framework by applying it to a simulated data set and then apply it to the HST/WFC3 (Hubble Space Telescope’s Wide-Field Camera 3) spectrum of the T-dwarf 2MASS J2339+1352. We retrieve sub-solar abundances of H2O and CH4 in the object at ∼0.1 dex precision. Additionally, we constrain the temperature structure to within ∼100 K in the photosphere. Our results demonstrate the promise of high-SNR spectra to provide high-precision abundance estimates of sub-stellar objects.

scholarly journals High-Precision Calibration of the Radiocarbon Time Scale, 3930–3230 Cal BC

Radiocarbon ◽  
1986 ◽  
Vol 28 (2B) ◽  
pp. 939-941 ◽  
Author(s):  
AFM de Jong ◽  
Bernd Becker ◽  
WG Mook
Keyword(s):  
River Basin ◽  
High Precision ◽  
Tree Rings ◽  
Time Scale ◽  
Danube River ◽  
The South ◽  
The Danube River ◽  
Danube River Basin

This paper contains 14C results obtained by the special high-precision proportional gas counter, designed by Tans and Mook (1978), on tree rings from the South German oak chronologies: Donau 7, 3, 10, and 12, originating from the Danube River basin (48° 24’ N, 10° 5’ E).

scholarly journals Highlights from HAWC

2019 ◽  
Vol 208 ◽  
pp. 14001
Author(s):  
H. León Vargas
Keyword(s):  
Energy Range ◽  
High Altitude ◽  
High Precision ◽  
Gamma Rays ◽  
Large Data ◽  
Cosmic Ray ◽  
Air Showers ◽  
Data Set ◽  
Sierra Negra Volcano ◽  
Selection Of

The HAWC (High Altitude Water Cherenkov) observatory, located on the slopes of the Sierra Negra volcano in the state of Puebla, Mexico, was designed with the goal of detecting gamma-rays in the Teraelectron- volt energy range. However, most of the air showers that are detected with the observatory, with a rate of ≈ 27 kHz, are of hadronic origin. This makes that, after three years of operations, HAWC has accumulated a very large data set that allows to perform cosmic-ray analysis of high precision. The details of the observatory operation, as well as a selection of recent results in cosmic-ray physics are discussed in this work.

First Determination of the Proton's Weak Charge

2015 ◽  
Vol 8 (3) ◽  
Author(s):  
Shelley A. Page
Keyword(s):  
Standard Model ◽  
High Precision ◽  
Standard Model Prediction ◽  
Data Set ◽  
Weak Charge ◽  
Newport News ◽  
The Standard Model ◽  
First Results ◽  
First Time

The weak charge of the proton has been determined for the first time via a high precision electron-proton scattering experiment, Qweak, carried out at Jefferson Laboratory (JLab) in Newport News, USA. The weak charge is a basic property in subatomic physics, analogous to electric charge. The Standard Model makes a prediction for the weak charges of protons and other particles. First results described here are based on an initial 4% of the data set reported in 20131, with the ultimate goal of the experiment being a high precision Standard Model test conducted with the full Qweak data set. These initial results are consistent with the Standard Model prediction; they serve as an important first determination of the proton’s weak charge and a proof of principle that the ultimate goals are within reach.

Chronometric calibration of mid-Ordovician to Tournaisian conodont zones: a compilation from recent graphic-correlation and isotope studies

1992 ◽  
Vol 129 (6) ◽  
pp. 709-721 ◽  
Author(s):  
Barry G. Fordham
Keyword(s):  
High Resolution ◽  
High Precision ◽  
Time Scale ◽  
Lower Devonian ◽  
New South ◽  
Upper Ordovician ◽  
South Wales ◽  
Isotope Studies ◽  
Stratotype Section ◽  
Upper Silurian

AbstractThree available graphic-correlation analyses are used to calibrate mid-Palaeozoic conodont zonations: Sweet's scheme for the mid- to Upper Ordovician; Kleffner's for the mid- to Upper Silurian; and Murphy & Berry's for the lower and middle Lower Devonian. The scheme of Sweet is scaled by applying the high-precision U-Pb zircon date of Tucker and others for the Rocklandian and linked with that of Kleffner by scaling the graptolite sequence of the Ordovician-Silurian global stratotype section to fit two similarly derived dates from this sequence. The top of Kleffner's scheme, all of Murphy & Berry's, as well as standard zones to the Frasnian are calibrated by using tie-points of the latest Cambridge-BP time-scale (GTS 89). However, the recent microbeam zircon date by Claoué-Long and others for the Hasselbachtal Devonian-Carboniferous auxiliary stratotype is used to calibrate the standard Famennian zones. Also the similarly derived but preliminary determination reported by Roberts and others from the Isismurra Formation of New South Wales is tentatively taken as the top of the Tournaisian and so used to calibrate Tournaisian zones. Despite the considerable extrapolation required to compile these schemes and their inherent errors, the resultant time-scale closely agrees with other dates of Tucker and others from the Llanvirn as well as the GTS 89 Homerian-Gorstian tie-point. This suggests that stratigraphic methods can be usefully applied to geochronometry. The Llandovery appears to have lasted longer (16 m. y.) than usually envisaged and the Ordovician-Silurian boundary may need to be lowered to approximately 443.5 Ma. Certainly, chrons varied widely in duration and further stratigraphic studies to estimate their relative durations as well as high-resolution dating for their calibration will be crucial to more accurate biochronometries.

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