Obtaining accurate radiocarbon (14C) results from wood samples requires the extraction of cellulose. In the past, this has been done using different combinations of methods including acidified bleaching, acid-base-acid, and strong bases. This often becomes a time-consuming task in most analyses, especially when single ring isotope chronologies are needed from wood samples. Using 14C and Fourier-transform infrared spectroscopy (FTIR), we tested four different pretreatment methods to determine their ability to produce high quality cellulose. We then adjusted the best methods to determine a method for pretreating wood laths of multiple rings. A sequence of base-acid-base-acid-bleach + strong base (BABAB+) and BABAB produced the most accurate results when compared to the Bomb20 Northern Hemisphere Zone 1 curve with an average difference in Δ14C of 1.3‰ and 5.8‰ respectively. These methods were adjusted to pretreat an entire wood lath and a comparison of the FTIR results suggest that our adjusted BABAB+ and BABAB produced high quality cellulose comparable to that of an individually pretreated ring. The possibility to pretreat wood lath samples has the potential to more than double the number of tree rings which can be pretreated in a week. This is a significant reduction in time when creating long tree ring chronologies.

The eastern Great Lakes Late Quaternary timescale is based on older thermoluminescence dates and on uncalibrated radiocarbon dates from extensive sections along the north shores of Lakes Erie and Ontario. New optically stimulated luminescence dates from Late Quaternary delta sediments from the north shores of Lake Erie at Sand Hills Park give consistent ages of 23.5 to 20.5 ka. This is 4 to 7 ka older than previously assigned based on lithologic correlation with 16.5 ka calibrated radiocarbon dated sediments 5 km to the west at Vanderven. On the existing eastern Great Lakes stratigraphy, it puts deposition of these Sand Hills Park sediments in the Erie interstadial and not in the fluctuating postglacial glacial retreat of the Mackinaw phase to which the Vanderven sediments belong. The Sand Hills delta and underlying diamicts must have been overridden by the Porty Bruce advance at 18 ka. IntCal20 calibration of existing radiocarbon ages suggests that the physical stratigraphic relations of the various Wisconsin units are accurate and that the existing timescale is simply too young.

The IntCal family of radiocarbon (14C) calibration curves is based on research spanning more than three decades. The IntCal group have collated the 14C and calendar age data (mostly derived from primary publications with other types of data and meta-data) and, since 2010, made them available for other sorts of analysis through an open-access database. This has ensured transparency in terms of the data used in the construction of the ratified calibration curves. As the IntCal database expands, work is underway to facilitate best practice for new data submissions, make more of the associated metadata available in a structured form, and help those wishing to process the data with programming languages such as R, Python, and MATLAB. The data and metadata are complex because of the range of different types of archives. A restructured interface, based on the “IntChron” open-access data model, includes tools which allow the data to be plotted and compared without the need for export. The intention is to include complementary information which can be used alongside the main 14C series to provide new insights into the global carbon cycle, as well as facilitating access to the data for other research applications. Overall, this work aims to streamline the generation of new calibration curves.

Temporal and spatial variation in radiocarbon (14C) in the atmosphere has been the subject of investigation from the first pioneering work of Libby and Arnold. However, as the precision of measurements has improved, now by almost two orders of magnitude, what constitutes a significant variation has also changed. Furthermore, it has become possible to test degrees of variation over much longer timescales and with ever wider geographic coverage. As knowledge has improved, the interpretation of 14C measurements has had to be revised. These re-evaluations, and the loss of chronological precision that comes with accurate calibration, have often been seen as an unfortunate drawback in the 14C dating method. However, these problems have stimulated extensive research in global 14C records, statistical methods for dealing with complex 14C data, and measurement methods. This research has provided a wealth of information useful for other scientific challenges, most notably the quantification of the global carbon cycle, but also enabled, in the right circumstances, measurement precision an order of magnitude better than if there had been no variation in atmospheric 14C. Challenges remain but the research undertaken for 14C calibration has, through its ingenuity and innovation, provided rich scientific dividends in both chronology and broader geoscience.

Radiocarbon (14C) concentrations in the oceans are different from those in the atmosphere. Understanding these ocean-atmospheric 14C differences is important both to estimate the calendar ages of samples which obtained their 14C in the marine environment, and to investigate the carbon cycle. The Marine20 radiocarbon age calibration curve is created to address these dual aims by providing a global-scale surface ocean record of radiocarbon from 55,000–0 cal yr BP that accounts for the smoothed response of the ocean to variations in atmospheric 14C production rates and factors out the effect of known changes in global-scale palaeoclimatic variables. The curve also serves as a baseline to study regional oceanic 14C variation. Marine20 offers substantial improvements over the previous Marine13 curve. In response to community questions, we provide a short intuitive guide, intended for the lay-reader, on the construction and use of the Marine20 calibration curve. We describe the choices behind the making of Marine20, as well as the similarities and differences compared with the earlier Marine calibration curves. We also describe how to use the Marine20 curve for calibration and how to estimate ΔR—the localized variation in the oceanic 14C levels due to regional factors which are not incorporated in the global-scale Marine20 curve. To aid understanding, illustrative worked examples are provided.

More than eight decades have passed since Edmonds's introduction to the rock-cut Tomb of Qizqapan, yet there are still ambiguities and questions regarding a number of aspects, specifically its dating. Different dates from the Median, Achaemenid, Seleucid, and Parthian periods have been proposed for this monument. However, out of all the proposed eras, none has been fully accepted by the majority of archaeologists, and disagreements regarding the date still continue. This article reviews and analyses previous proposals and discusses and evaluates other elements which affect the dating of this monument. The results show that by taking into account several factors, the most probable date for this tomb is the fourth century B.C., contemporaneous with the late Achaemenid and the early Seleucid period. The conclusion is that Qizqapan does have a Median identity but not a Median period date.

This paper integrates the first rock art directly dated with radiocarbon (14C) in Southeast Asia with the archaeological activity in the area and with stylistically similar rock art in the region. Peñablanca is a hotspot of archaeological research that includes the oldest dates for human remains in the Philippines. The caves in Peñablanca with known rock art were revisited and only 37.6% of the original recorded figures were found; the others are likely lost to agents of deterioration. A sample was collected from an anthropomorph and accelerator mass spectrometry (AMS) dated to 3570–3460 cal BP. The date corresponds to archaeological activity in the area and provides a more holistic view of the people inhabiting the Peñablanca caves at that time. A systematic review was used to find similar black anthropomorph motifs in Southeast Asia to identify potential connections across the region and provide a possible chronological association.

The excavation of a building in the village of Felanitx in the eastern part of the island of Mallorca (Balearic Islands) has revealed the existence of a small necropolis. The inhumations did not provide grave goods except for a bronze belt buckle for which the typological study suggests a Late Antique chronology. The stratigraphical sequence however seems to suggest a possible evolution of the space across time since some graves are cut by others. In order to obtain an absolute date for the necropolis and to verify if there are chronological differences between the graves, a total of 6 human bones samples have been 14C dated by AMS. The results of the radiocarbon dating confirm a Late Antique chronology (4th to 7th century AD) for the graves but do not suggest a chronological evolution. Despite the fact that the knowledge of the necropolis is still fragmentary, the results are extremely important because they provide an absolute date for a Late Antique necropolis in the Mallorcan rural area.

We present a new biennial record of radiocarbon (14C) measured in Danish oak. The new record covers the years 1251–1378 CE, thereby spanning the Grand Solar Minimum known as the Wolf Minimum. Two oak samples from every other year were measured at the AMS facility at Aarhus University (Denmark), resulting in an average precision of 1.4‰ for the record. Spectral analysis of the new record revealed two peaks at 27 and 9.1 years, which could indicate the Hale cycle was lengthened and the Schwabe cycle shortened during the Wolf Minimum, but it is also possible that the amplitude of the Schwabe cycle was too small to be accurately identified with the acquired precision of this record. The record was bandpass filtered to investigate the variability of the amplitude in different bands, which showed a dampening of the amplitude during the second half of the Wolf Minimum in bands centered on the Schwabe and the Hale cycle, respectively. A reconstruction of the solar modulation function, Φ, also showed a periodicity of ca. 9 years, and indicated that the Wolf Minimum was preceeded by one cycle of decreased solar activity.

Despite the increased use of dating technology for finding and forming romantic relationships, location remains relevant for relationship formation. While current research on relationship formation attends to the ratio of marriageable men to women, marital attitudes, and gendered racial exclusion, this research does not always consider a nuanced look at how location can also constrain opportunities to make short- or long-term romantic connections. Drawing on interviews with 111 Asian, White, Black, and Latina heterosexual college-educated women between the ages of twenty-five and thirty-three, I find that regardless of race/ethnicity, women observe that some places provide limited opportunities to meet men and that the mismatch between their dating norms, beliefs, and/or expectations for relationships and the location where they reside make their search more difficult. Women of color additionally note that some locations provide fewer opportunities for same-race and/or interracial dating than others. I also find that women of color are more likely to employ strategies to address their locational barriers than White women.

Therefore, I argue that not only does location continue to matter for forming romantic connections in the digital age, but that location and race also intersect to create unique locational barriers for women of color. This intersection, consequently, demonstrates that the opportunities for relationship formation remain stratified despite the rise of dating technology.

Connecting calendar ages to radiocarbon (14C) ages, i.e. constructing a calibration curve, requires 14C samples that represent, or are closely connected to, atmospheric 14C values and that can also be independently dated. In addition to these data, there is information that can serve as independent tests of the calibration curve. For example, information from ice core radionuclide data cannot be directly incorporated into the calibration curve construction as it delivers less direct information on the 14C age–calendar age relationship but it can provide tests of the quality of the calibration curve. Furthermore, ice core ages on 14C-dated volcanic eruptions provide key information on the agreement of ice core and radiocarbon time scales. Due to their scarcity such data would have little impact if directly incorporated into the calibration curve. However, these serve as important “anchor points” in time for independently testing the calibration curve and/or ice-core time scales. Here we will show that such information largely supports the new IntCal20 calibration record. Furthermore, we discuss how floating tree-ring sequences on ice-core time scales agree with the new calibration curve. For the period around 40,000 years ago we discuss unresolved differences between ice core 10Be and 14C records that are possibly related to our limited understanding of carbon cycle influences on the atmospheric 14C concentration during the last glacial period. Finally, we review the results on the time scale comparison between the Greenland ice-core time scale (GICC05) and IntCal20 that effectively allow a direct comparison of 14C-dated records with the Greenland ice core data.

The deposits in Cumberland Bone Cave (Allegany County, Maryland) preserved one of the most taxonomically diverse pre-radiocarbon Pleistocene faunas in the northeastern United States. The site has long been recognized as an important record of Pleistocene life in the region, but numerical age control for the fauna was never developed, and hypotheses for its age have been based upon biochronological assessments of the mammalian fauna. We used fossil teeth and preserved sediment housed in museum collections to obtain the first numerical age assessment of the fauna from Cumberland Bone Cave. Coupled U-series Electron Spin Resonance (US-ESR) was used to date fossil molars of the extinct peccary, Platygonus sp. The age estimates of two teeth gave ages of 722 ± 64 and 790 ± 53 ka. Our results are supported by previously unpublished paleomagnetic data generated by the late John Guilday, and by plotting length-width of the first molar (m1) of Ondatra (muskrats) from Cumberland Bone Cave on the chronocline of Ondatra molar evolution in North America. Our age assessments are surprisingly close to the age estimate previously proposed by Charles Repenning, who based his age on a somewhat complicated model of speciation and morphotype evolution among arvicoline rodents.

Violence in dating relationships constitutes a serious problem, thus, the study of related factors could help to better understand this violence and intervene in it. This study had three goals: (1) To analyze the prevalence of dating violence in adolescents under residential care settings according to sex and age; (2) to explore the relationships between victimization and perpetration in adolescents’ dating violence, sexist attitudes and clinical variables; and (3) to identify variables associated to adolescents’ dating violence (victimization and perpetration). The sample comprised 271 adolescents (54.6% boys and 45.4% girls), aged between 12 and 17 years (M = 15.23, SD = 1.60). The victimization (R2 = .17, p <.001) and perpetration (R2 = .20. p < .001) results showed prevalence rates higher than those of previous studies. Sex was not a differentiating factor for perpetration of dating violence, but age was: the older they were, the higher the perpetration rate. In the case of victimization, an interaction between sex and age was found. Results showed that age, sex, hostile sexism and depression were variables associated to victimization whereas age, hostile sexism and depression were associated to perpetration of dating violence.