A new R function for the Internal External Uncertainty (IEU) model

A new function (calc IEU) is now available in the latest version of the R Luminescence package (version 0.4.2). The calc IEU function can be used to calculate an equivalent dose (De)value for a given dose distribution using the Internal External Uncertainty (IEU) model. The IEU model is used in luminescence dating to determine a De value for a partially-bleached sample by calculating the weighted mean from the well bleached part of a partially-bleached population. The new calc IEU function automates the calculation of the IEU model so that the results are produced rapidly and reproducibly. This is advantageous as the user can easily perform sensitivity tests of the model in response to changing input parameters

“CODE LABOR”: An Evidence Based and Interdisciplinary Approach to Managing Women Experiencing Precipitous Labor Outside of the Labor and Delivery Unit

Local Problem: Precipitous deliveries can incite adverse obstetrical events and poor outcomes. In one rural northern Alabama hospital, 75-100 babies are delivered monthly with an average of two precipitous deliveries occurring monthly. Objective: The intent of the work was to address a cohort of obstetrical (OB) and emergency department (ED) nurses’ knowledge gaps regarding the care of women experiencing precipitous labor outside of the labor and delivery (L&D) unit. DESIGN A quasi-experimental design aimed at quality improvement at the healthcare system’s level was developed. A non-probability, quota sampling method was used to gather data. Participants: Fifty-seven ED and OB RNs participated. Intervention/Measurements: Education specific to managing women experiencing precipitous labor was presented. Surveys were conducted to evaluate perceived limitations and improvements in interdisciplinary teamwork and communication. Results: Pre-educational data revealed moderate-well communication was felt to occur between the OB and ED nurses and 50.8% of participating nurses felt comfortable or neutral when caring for an OB patient experiencing precipitous labor and delivery. Post-educational data revealed improved interdisciplinary communication and RN comfort level. Nine out of 343 women experienced precipitous labor during the project\u27s time frame. Seven delivered within 7 to 40 minutes after arriving to the L&D unit and two deliveries occurred outside of the L&D unit. Interviews revealed positive utilization of the CODE LABOR policy. Hospital Consumer Assessments of Healthcare Providers and Systems (HCHAPS) data were evaluated for process improvement related to patient experience. Data in the last quarter 2018 disclosed an 84.3% satisfaction rate of nurse/patient communication and a 70.6% recommendation of the hospital to friends and family. First quarter data 2019 revealed an 80.2% satisfaction rate of nurse/patient communication and 71.7% that would recommend the hospital to friends and family. Conclusion: Instituting an interdisciplinary policy helps nurses increase assessment skills, critical decision making processes, communication, and teamwork

Internal U, Th and Rb concentrations of alkali-feldspar grains:Implications for luminescence dating

This study assesses whether internal U, Th and Rb concentrations of single grains of alkali-feldspar can impact upon luminescence dating. Internal alpha dose-rates determined for two sedimentary samples calculated from mean U and Th concentrations accounted for ∼10% of the total dose-rates, while internal beta dose-rates from mean Rb concentrations accounted for ∼2%. Depth profiles of measurements penetrating into each grain show that internal U and Th concentrations varied between grains, where some grains had effective internal alpha dose-rates up to 1.8 Gy/ka (32% of the total dose-rate). K concentrations inferred from Rb (KRb) for individual grains suggest that internal U and Th concentrations are related to the feldspar composition. Grains with KRb > 6% had low U and Th, and grains with KRb < 6% had higher U and Th concentrations. Internal alpha and beta dose-rates of the perthitic and Na-rich grains contaminating the density-separated K-feldspar fractions had a significant impact upon the single-grain De distributions, which was estimated to be equivalent to overdispersion values of ∼10 – 15%. The scatter in the De distributions arising from internal alpha and beta dose-rates for both samples could be reduced by selecting only the brightest 20% of grains for luminescence dating

Luminescence dating of glacial advances at Lago Buenos Aires (∼46 °S), Patagonia

Understanding the timing of past glacial advances in Patagonia is of global climatic importance because of the insight this can provide into the influence on glacier behaviour of changes in temperature and precipitation related to the Southern Westerlies. In this paper we present new luminescence ages determined using single grains of K-feldspar from proglacial outwash sediments that were deposited by the Patagonian Ice Sheet around Lago Buenos Aires (∼46 °S), east of the contemporary Northern Patagonian Icefield. The new luminescence ages indicate that major outwash accumulations formed around ∼110 ± 20 ka to 140 ± 20 ka and that these correspond to the Moreno I and II moraine ridges, which were previously dated using cosmogenic isotope dating to 150 ± 30 ka. Luminescence dating at Lago Buenos Aires has also identified outwash sediments that were deposited during glacial advances ∼30.8 ± 5.7 ka and ∼34.0 ± 6.1 ka (MIS 3) that are not recorded in the moraine record. Younger outwash accumulations were then deposited between ∼14.7 ± 2.1 and 26.2 ± 1.6 ka which correspond to the Fenix I – V moraine ridges. The combined chronology suggests that glacial advances occurred ∼110 ± 20 ka to 150 ± 30 ka (MIS 6), ∼30.8 ± 5.7 ka to ∼34.0 ± 6.1 ka (MIS 3), and ∼14.7 ± 2.1 to 26.2 ± 1.6 ka (MIS 2) at Lago Buenos Aires. Overall luminescence dating using single grains of K-feldspar has excellent potential to contribute towards the ever-increasing geochronological dataset constraining the timings of glacial advances in Patagonia

Glacier expansion in central Patagonia during the Antarctic Cold Reversal followed by retreat and stabilisation during the Younger Dryas

The spatial-temporal footprint of millennial-scale climate events during the last glacial-interglacial transition can yield insights into the underlying drivers of climate change, but remains poorly resolved in Patagonia. Here, we assess the glacier response to abrupt cold events and palaeolake evolution using geomorphological mapping along with ages and optically stimulated luminescence ages from near Lago Belgrano (47.9° S) on the eastern side of Monte San Lorenzo. The former Belgrano glacier was sustained by a climatically sensitive ice cap, making the site ideal for investigating the glacier response to abrupt cold reversals. Our data reveal an extensive re-advance at 13.1 0.6 ka, consistent with cooling and increased precipitation during the Antarctic Cold Reversal (ACR). Subsequently, ice retreated by at least 10 km and created an ice-dammed proglacial lake in the Belgrano valley. Rapid recession was punctuated by smaller advances/still-stands sufficient to maintain an ice-dam for the palaeolake and deposit a lateral moraine dated at 12.4 0.3 ka during the Younger Dryas (YD). The final withdrawal of glaciers to the mountains allowed the palaeolake to drain and resulted in an Atlantic/Pacific drainage reversal. This marks the final separation of the Patagonian Ice Sheet into the individual ice fields at the YD-Holocene transition. Our data demonstrate the dominant ACR climate signal in central Patagonia, but also reveals a co-occurrence of the northern hemisphere YD signal, albeit of smaller magnitude. The ACR re-advance was primarily climatically controlled, but its relative magnitude was likely a consequence of ice divide migration and ice flow re-routing during the break-up of the Patagonian Ice Sheet

An integration of numerical modelling and paleoenvironmental analysis reveals the effects of embankment construction on long‐term salt marsh accretion

This dataset contains the results discussed in the journal article titled 'An integration of numerical modelling and paleoenvironmental analysis reveals the effects of embankment construction on long-term salt marsh accretion'

Erosion rates in a wet, temperate climate derived from rock luminescence techniques

Abstract. A new luminescence erosion-meter has huge potential for inferring erosion rates on sub-millennial scales for both steady and transient states of erosion, which is currently not possible with any existing techniques capable of measuring erosion. This study applies new rock luminescence techniques to a well-constrained scenario provided by the Beinn Alligin rock avalanche, NW Scotland. Boulders in this deposit are lithologically consistent, have known cosmogenic nuclide ages, and independently-derived Holocene erosion rates. We find that luminescence-derived exposure ages for the Beinn Alligin rock avalanche were an order of magnitude younger than existing cosmogenic nuclide exposure ages, suggestive of high erosion rates (as supported by field evidence of quartz grain protrusions on the rock surfaces). Erosion rates determined by luminescence were consistent with independently-derived rates measured from boulder-edge roundness. Inversion modelling indicates a transient state of erosion reflecting the stochastic nature of erosional processes over the last ~4 ka in the wet, temperate climate of NW Scotland. Erosion was likely modulated by known fluctuations in moisture availability, and to a lesser extent temperature, which controlled the extent of chemical weathering of these highly-lithified rocks prior to erosion. The use of a multi-elevated temperature, post-infra-red, infra-red stimulated luminescence (MET-pIRIR) protocol (50, 150 and 225 °C) was advantageous as it identified samples with complexities introduced by within-sample variability (e.g. surficial coatings). This study demonstrates that the luminescence erosion-meter can infer accurate erosion rates on sub-millennial scales and identify transient states of erosion (i.e. stochastic processes) in agreement with independently-derived erosion rates for the same deposit. </jats:p