Recent research has shown the potential of speleothem δ13C to record a range of environmental processes. Here, we report on 230Th-dated stalagmite δ13C records for southwest Sulawesi, Indonesia, over the last 40,000 yr to investigate the relationship between tropical vegetation productivity and atmospheric methane concentrations. We demonstrate that the Sulawesi stalagmite δ13C record is driven by changes in vegetation productivity and soil respiration and explore the link between soil respiration and tropical methane emissions using HadCM3 and the Sheffield Dynamic Global Vegetation Model. The model indicates that changes in soil respiration are primarily driven by changes in temperature and CO2, in line with our interpretation of stalagmite δ13C. In turn, modelled methane emissions are driven by soil respiration, providing a mechanism that links methane to stalagmite δ13C. This relationship is particularly strong during the last glaciation, indicating a key role for the tropics in controlling atmospheric methane when emissions from high-latitude boreal wetlands were suppressed. With further investigation, the link between δ13C in stalagmites and tropical methane could provide a low-latitude proxy complementary to polar ice core records to improve our understanding of the glacial–interglacial methane budget.

Radiocarbon (F14C) and stable carbon (δ13C) values were measured in single grains of spring barley (Hordeum vulgare L.) from the sample archive from two adjacent sites of the Long-term Experiments (LTEs) Hoosfield Spring Barley at Rothamsted Research (Harpenden, Hertfordshire, UK), covering the growing periods (March to September) of 1852 to 2020. F14C data of the barley grain confirm that recent values are approaching and will decline below the “nominal” F14C value of 1, tracking a similar decrease reported in other studies. Importantly, the measured δ13C values reveal a different temporal decline over the pre-bomb and post-bomb timescale. Detailed statistical analysis of δ13C data along with δ13C analysis of independent, archived barley mash samples, verifies and quantifies the extent and rate of this decline. Evidence presented from the barley grain and barley mash samples suggests a clear breakpoint in δ13C data occurring in 1995, where the rate of change alters, in that the slope in δ13C data for the pre-1995 period is declining at 1.4‰ per century, and the slope in δ13C for the post-1995 period is declining at 3.6‰ per century. Such a consistent shift in δ13C data could be used with F14C values to extend the use of the bomb peak for forensic, ecological, and environmental applications.

Radiocarbon (14C) dating of sediment deposition around Antarctica is often challenging due to heterogeneity in sources and ages of organic carbon in the sediment. Chemical and thermochemical techniques have been used to separate organic carbon when microfossils are not present. These techniques generally improve on bulk sediment dates, but they necessitate assumptions about the age spectra of specific molecules or compound classes and about the chemical heterogeneity of thermochemical separations. To address this, the Rafter Radiocarbon Laboratory has established parallel ramped pyrolysis oxidation (RPO) and ramped pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) systems to thermochemically separate distinct carbon fractions, diagnose the chemical composition of each fraction, and target suitable RPO fractions for radiocarbon dating. Three case studies of sediment taken from locations around Antarctica are presented to demonstrate the implementation of combined RPO-AMS and Py-GC-MS to provide more robust age determination in detrital sediment stratigraphy. These three depositional environments are good examples of analytical and interpretive challenges related to oceanographic conditions, carbon sources, and other factors. Using parallel RPO-AMS and Py-GC-MS analyses, we reduce the number of radiocarbon measurements required, minimize run times, provide context for unexpected 14C ages, and better support interpretations of radiocarbon measurements in the context of environmental reconstruction.

GIRI (Glasgow International Radiocarbon Intercomparison) was designed to meet a number of objectives, including to provide an independent assessment of the analytical quality of the laboratory/measurement and an opportunity for a laboratory to participate and improve (if needed). The principles in the design of GIRI were to provide the following: (a) a series of unrelated individual samples, spanning the dating age range, (b) linked samples to earlier intercomparisons to allow traceability, (c) known age samples, to allow independent accuracy checks, (d) a small number of duplicates, to allow independent estimation of laboratory uncertainty, and (e) two categories of samples—bulk and individual—to support laboratory investigation of variability. All of the GIRI samples are natural (wood, peat, and grain), some are known age, and overall their age spans approx. >40,000 years BP to modern. The complete list of sample materials includes humic acid, whalebone, grain, single ring dendro-dated samples, dendro-dated wood samples spanning a number of rings (e.g., 10 rings), background and near background samples of bone and wood. We present an overview of the results received and preliminary consensus values for the samples supporting a more in-depth evaluation of laboratory performance and variability.

The SUERC Radiocarbon Laboratory reports approximately 3000 unknown samples per year with an additional 1200 samples processed for quality assurance purposes. In addition to the primary OxII standard (SRM-4990C) required for AMS batch normalization, secondary “known-age” standards have been used over many years to evaluate individual batch quality. These have included wood (as prepared alpha-cellulose), barley mash, humic acid, a background mammoth bone, known-age bones, and a whisky sample. In this paper, we present some of the results gathered over routine laboratory operation (for more than 10 years) and examine the results illustrating how they are being used to monitor and quality assure performance. Since many of these samples have also been used in the Glasgow intercomparisons, we will also reflect on the results, as well as the actual and potential uses of such samples.

Background: Perinatal arterial ischemic stroke (PAIS) is a focal brain injury in term neonates, identified postnatally but presumed to occur around birth. Early risk detection and targeted treatments are limited. We developed and validated a diagnostic risk prediction model from common clinical factors to predict a term neonate’s probability of PAIS. Methods: A diagnostic prediction model was developed using multivariable logistic regression. Common pregnancy, delivery, and neonatal clinical factors were collected across four registries. Variable selection was based on peer-reviewed literature. Participant inclusion criteria were term birth and no underlying predisposition to stroke. The primary outcome was discriminative accuracy of the model predicting PAIS, measured by the concordance (C-) statistic. Results: 2571 participants (527 cases, 2044 controls) were eligible for analysis. Nine variables were included in the model – maternal age, tobacco exposure, recreational drug exposure, pre-eclampsia, chorioamnionitis, maternal fever, emergency c-section, low 5-minute Apgar score, and sex – to predict the risk of PAIS in a term neonate. This model demonstrated good discrimination between cases and controls (C-statistic 0.73) and model fit (Hosmer-Lemeshow p=0.20). Conclusions: Clinical variables can be used to develop and internally validate a model of PAIS risk prediction. Identifying high-risk neonates for early screening and treatment could reduce lifelong morbidity.

Background: Perinatal arterial ischemic stroke (PAIS) is a leading cause of hemiparetic cerebral palsy. Multiple risk factors are associated with PAIS but studies are limited by small sample sizes and complex interactions. Unbiased machine learning applied to larger datasets may enable the development of robust predictive models. We aimed to use machine learning to identify risk factors predictive of PAIS and compare these to the existing literature. Methods: Common data elements of maternal, delivery, and neonatal factors were collected from three perinatal stroke registries and one control sample over a 7-year period. Inclusion criteria were MRI-confirmed PAIS, term birth, and idiopathic etiology. Random forest machine learning in combination with feature selection was used to develop a predictive model of PAIS. Results: Total of 2571 neonates were included (527 cases, 2044 controls). Risk factors uniquely identified through machine learning were infertility, miscarriage, primigravida, and meconium. When compared, factors identified through both literature-based selection and machine learning included maternal age, fetal tobacco exposure, intrapartum fever, and low 5-minute APGAR. Conclusions: Machine learning offers a novel, less biased method to identify PAIS predictors and complex pathophysiology. Our findings support known associations with concepts of placental disease and difficult fetal transition and may support early screening for PAIS.

This Perceptual Dialectology (PD) study asked residents of Cardiff, Wales, about their perceptions of English in the United Kingdom (UK). In addition, because face to face exposure to dialect variation has rarely been included as a variable in PD studies, participants were asked about their travel experience to ascertain whether this might influence their responses to a PD map task. Participants’ responses to the map task were analyzed using ArcGIS to create composite maps. Results show that these Cardiffians perceive “dialect or regional” speech boundaries to be located around major cities in England and Wales but also southwest Wales. Composite maps and polygon counts suggest that the more traveled respondents have a more nuanced perception of dialect regions than those who claim to travel less, suggesting that travel experience may influence PD participants’ responses to map tasks.

The Mini International Neuropsychiatric Interview (MINI) is a short diagnostic structured interview (DSI) developed in France and the United States to explore 17 disorders according to Diagnostic and Statistical Manual (DSM)-III-R diagnostic criteria. It is fully structured to allow administration by non-specialized interviewers. In order to keep it short it focuses on the existence of current disorders. For each disorder, one or two screening questions rule out the diagnosis when answered negatively. Probes for severity, disability or medically explained symptoms are not explored symptom-by-symptom. Two joint papers present the inter-rater and test-retest reliability of the MINI the validity versus the Composite International Diagnostic Interview (CIDI) (this paper) and the Structured Clinical Interview for DSM-III-R patients (SCID) (joint paper). Three-hundred and forty-six patients (296 psychiatric and 50 non-psychiatric) were administered the MINI and the CIDI ‘gold standard’. Forty two were interviewed by two investigators and 42 interviewed subsequently within two days. Interviewers were trained to use both instruments. The mean duration of the interview was 21 min with the MINI and 92 for corresponding sections of the CIDI. Kappa coefficient, sensitivity and specificity were good or very good for all diagnoses with the exception of generalized anxiety disorder (GAD) (kappa = 0.36), agoraphobia (sensitivity = 0.59) and bulimia (kappa = 0.53). Interrater and test-retest reliability were good. The main reasons for discrepancies were identified. The MINI provided reliable DSM-III-R diagnoses within a short time frame, The study permitted improvements in the formulations for GAD and agoraphobia in the current DSM-IV version of the MINI.

The Mini International Neuropsychiatric Interview (MINI) is a short diagnostic structured interview, developed in clinician (MINI-CR) and patient-rated (MINI-PR) formats, for 17 Diagnostic and Statistical Manual (DSM)-III-R Axis I psychiatric disorders. This study, which investigates the validity of the MINI in relation to the Structured Clinical Interview for DSM-III-R Patients (SCID-P), was conducted in conjunction with a similar study, investigating the validity of the MINI in relation to the Composite International Diagnostic Interview (CIDI) for International Statistical Classification of Disease (ICD)-10. Both studies also examined the inter-rater and test-retest reliability of the MINI. Three hundred and seventy subjects (330 in Florida and 40 in Paris) participated in the validation of the MINI versus the SCID-P. Of these, 308 had at least one psychiatric disorder and 62 were non-patient adult controls. Eighty of the subjects (40 in Florida and 40 in Paris) also participated in the parallel study of the validity of the MINI versus the CIDI. The 330 Florida subjects first completed the patient-rated version of the MINI. All subjects were administered the MINI-CR (after the MINI-PR in the case of the Florida subjects), followed by the SCID-P. The MINI-CR was rated by two interviewers for 42 subjects in Florida and 42 in Paris (inter-rater reliability test) and readministered by a third blind interviewer one to two days after the initial rating (test-retest reliability test). Overall, the results supported the validity and reliability of the MINI. In addition, administration of the MINI-CR took half as long as administration of corresponding sections of the SCID-P. The application of short structured interviews in clinical and research settings is discussed.

A physical oceanographic, geophysical and marine geological survey of Edward VIII Gulf, Kemp Coast, collected data from conductivity–temperature–depth casts, multi-beam bathymetric swath mapping and 3.5 kHz sub-bottom surveying. Modified circumpolar deep water (mCDW) is observed in Edward VIII Gulf, as well as notable bathymetric features including mega-scale glacial lineations and a 1750 m-deep trough. Sedimentological, geochemical, rock-magnetic and micropalaeontological analysis of two kasten cores document regional palaeoclimate and palaeo-oceanographic conditions over the past 8000 years, with a warm period occurring from c. 8 to 4 ka and a shift to cooler conditions beginning at c. 4 ka and persisting until at least 0.9 ka. Sediment packages > 40 m thick within deep troughs in Edward VIII Gulf present potential targets for higher-resolution Holocene and deglacial climate studies. Despite the presence of mCDW on the shelf, inland bed topography consisting of highland terrain suggests the likelihood of relative stability of this sector of the East Antarctic Ice Sheet.

Over the past 30 years, the format of the radiocarbon (14C) intercomparison studies has changed, however, the selection of sample types used in these studies has remained constant—namely, natural and routinely dated materials that could subsequently be used as in-house reference materials. One such material is peat which has been used 12 times, starting with the ICS in 1988. Peat from Iceland (TIRI), Ellanmore (TIRI), Letham Moss (ICS, VIRI, and SIRI), and St Bees, UK (FIRI and VIRI) have been used, as well as a near-background peat from Siberia. In the main, these peat samples have been provided as the humic acid fraction, with the main advantage being that the humic acid is extracted in solution and then precipitated (the solution phase providing the homogenisation) which is a key requirement for a reference material. In this paper, we will revisit the peat results and explore their findings. In addition, for the last 8 years, the Letham Moss sample has been used in the SUERC 14C laboratory as an in-house standard or reference material. This has resulted in several thousand measurements. Such a rich data set is explored to illustrate the benefits arising from the intercomparison program.

We evaluate the utility of the National Surveys of Attitudes and Sexual Lifestyles (Natsal) undertaken in 2000 and 2010, before and after the introduction of the National Chlamydia Screening Programme, as an evidence source for estimating the change in prevalence of Chlamydia trachomatis (CT) in England, Scotland and Wales. Both the 2000 and 2010 surveys tested urine samples for CT by Nucleic Acid Amplification Tests (NAATs). We examined the sources of uncertainty in estimates of CT prevalence change, including sample size and adjustments for test sensitivity and specificity, survey non-response and informative non-response. In 2000, the unadjusted CT prevalence was 4.22% in women aged 18–24 years; in 2010, CT prevalence was 3.92%, a non-significant absolute difference of 0.30 percentage points (95% credible interval −2.8 to 2.0). In addition to uncertainty due to small sample size, estimates were sensitive to specificity, survey non-response or informative non-response, such that plausible changes in any one of these would be enough to either reverse or double any likely change in prevalence. Alternative ways of monitoring changes in CT incidence and prevalence over time are discussed.

Bone is frequently dated in archaeological studies and, especially for very old bones (more than 40,000 years old), it is critical to have an accurate and precise measure of the material-specific background value and its associated uncertainty. The SUERC Radiocarbon Laboratory has obtained a mammoth bone as a background bone standard and an appropriate number are now routinely prepared and measured in each AMS batch, resulting in the accumulation of a large number of background bone results over a two-year period. Additionally, information on which of the two accelerator mass spectrometry (AMS) instruments was used to make the radiocarbon (14C) measurements, and which sample pretreatment method (modified Longin or modified ultrafiltration) was used to extract and purify the collagen, is recorded for each sample. These data have been used to estimate the laboratory bone background (to be subtracted from each unknown bone sample prepared in the laboratory) and its associated analytical uncertainty. The statistical analysis of the bone results has made use of a linear mixed effects model to examine the variation, and to apportion the overall variation between and within batches on both AMS instruments, and the different pretreatment methods used at SUERC.

We present a new surface-balance and ice-motion dataset derived from high-precision GPS measurements from a network of steel poles within three icefields of the Allan Hills blue-ice area, Antarctica. The surveys were conducted over a 14 year time period. Ice-flow velocities and mass- balance estimates for the main icefield (MIF) are consistent with those from pre-GPS era measurements but have much smaller uncertainties. The current study also extends these measurements through the near-western icefield (NWIF) to the eastern edge of the mid-western icefield (MWIF). The new dataset includes, for the first time, well-constrained evidence of upward motion within the Allan Hills MIF, indicating that old ice should be present at the surface. These data and terrestrial meteorite ages suggest that paleoclimate reconstructions using the surface record within the Allan Hills MIF could potentially extend the ice-core-based record beyond the 800 000 years currently available in the EPICA Dome C core.

The SUERC Radiocarbon Laboratory employs a one-step “background subtraction” method when calculating 14C ages. An interglacial wood (VIRI Sample K) is employed as the non-bone organic background standard, while a mammoth bone (LQH12) from Latton Quarry is used as the bone background standard. Results over several years demonstrate that the bone background is consistently around a factor of two higher and more variable than the wood background. As a result, the uncertainty on routine bone measurements is higher than for other sample types. This study investigates the factors that may contribute to the difference in F14C values and the higher variability. Preparations of collagen using modified Longin or ultrafiltration methods show no significant difference, nor does eliminating the collagen dissolution step. Two bone samples of known infinite age with respect to radiocarbon are compared and again no significant difference is observed. Finally, the quantity and age of the organic matter in the water used during the pretreatment is investigated and it is shown that there is insufficient organic matter in the reverse osmosis water to influence background values significantly. The attention is now on determining if incomplete demineralization could lead to contaminants being retained by the phosphate in the hydroxyapatite.