A late Holocene onset of Aboriginal burning in southeastern Australia

The extent to which Aboriginal Australians used fire to modify their environment has been debated for decades and is generally based on charcoal and pollen records rather than landscape responses to land-use change. Here we investigate the sensitivity of in-situ–produced 10Be, an isotope commonly used in geomorphological contexts, to anthropogenic perturbations in the southeastern Australian Tablelands. Comparing 10Be-derived erosion rates from fluvial sediment (8.7 ± 0.9 mm k.y.–1; 1 standard error, SE; n = 11) and rock outcrops (5.3 ± 1.4 mm k.y.–1; 1 SE; n = 6) confirms that landscape lowering rates integrating over 104–105 yr are consistent with rates previously derived from studies integrating over 104 to >107 yr. We then model an expected 10Be inventory in fluvial sediment if background erosion rates were perturbed by a low-intensity, high-frequency Aboriginal burning regime. When we run the model using the average erosion rate derived from 10Be in fluvial sediment (8.7 mm k.y.–1), measured and modeled 10Be concentrations overlap between ca. 3 ka and 1 ka. Our modeling is consistent with intensified Aboriginal use of fire in the late Holocene, a time when Aboriginal population growth is widely recognized

A standard, single dose of inhaled terbutaline attenuates hyperpnoea-induced bronchoconstriction and mast cell activation in athletes

Release of broncho-active mediators from mast cells during exercise hyperpnoea is a key factor in the pathophysiology of exercise-induced bronchoconstriction (EIB). Our aim was to investigate the effect of a standard, single dose of an inhaled β2-adrenoceptor agonist on mast cell activation in response to dry air hyperpnoea in athletes with EIB. Twenty-seven athletes with EIB completed a randomised, double blind, placebo-controlled, crossover study. Terbutaline (0.5 mg) or placebo was inhaled15 min prior to 8 min of eucapnic voluntary hyperpnoea (EVH) with dry air. Pre- and post-bronchial challenge, urine samples were analysed by enzyme immunoassay for 11β-prostaglandin(PG)F2α. The maximum fall in forced expiratory volume in 1 sec(FEV1) of 14 (12-20)% (median and interquartile range) following placebo was attenuated to 7 (5-9)% with the administration of terbutaline (P<0.001). EVH caused a significant increase in 11β-PGF2α from (27-57) ng·mmol creatinine-1 at baseline to (43-72) ng·mmol creatinine-1 at its peak post-EVH following placebo (P=0.002). The rise in 11β-PGF2α was inhibited with administration of terbutaline: 39 (28-44) ng·mmol creatinine-1 at baseline vs. 40 (33-58) ng·mmol creatinine-1 at its peak post-EVH (P=0.118). These data provide novel in vivo evidence of mast cell stabilisation following inhalation of a standard dose of terbutaline prior to bronchial provocation with EVH in athletes with EIB

Directly dating postglacial Greenlandic land-surface emergence at high resolution using in situ 10Be

Postglacial emergence curves are used to infer mantle rheology, delimit ice extent, and test models of the solid Earth response to changing ice and water loads. Such curves are rarely produced by direct dating of land emergence; rather, most rely on the presence of radiocarbon-datable organic material and inferences made between the age of sedimentary deposits and landforms indicative of former sea level. Here, we demonstrate a new approach, 10Be dating, to determine rates of postglacial land emergence in two different settings. In southern Greenland (Narsarsuaq/Igaliku), we date directly the exposure, as relative sea level fell, of gravel beaches and rocky outcrops allowing determination of rapid, post–Younger Dryas emergence. In western Greenland (Kangerlussuaq), we constrain Holocene isostatic response by dating the sequential stripping of terrace sediment driven by land-surface uplift, relative sea-level fall, and resulting fluvial incision. The technique we employ provides high temporal and elevation resolution important for quantifying rapid emergence immediately after deglaciation and less rapid uplift during the middle Holocene. 10Be-constrained emergence curves can improve knowledge of relative sea-level change by dating land emergence along rocky coasts, at elevations and locations where radiocarbon-datable sediments are not present, and without the lag time needed for organic material to accumulate

Erosion rates and sediment flux within the Potomac River basin quantified over millennial timescales using beryllium isotopes

Beryllium isotopes measured in detrital river sediment are often used to estimate rates of landscape change at a basin scale, but results from different beryllium isotope systems have rarely been compared. Here, we report measurements of in situ and meteoric 10Be (10Bei and 10Bem, respectively) along with measurements of reactive and mineral phases of 9Be (9Bereac and 9Bemin, respectively) to infer long-term rates of landscape change in the Potomac River basin, North America. Using these data, we directly compare results from the two different 10Be isotope systems and contextualize modern sediment flux from the Potomac River basin to Chesapeake Bay. Sixty-two measurements of 10Bei in river sand show that the Potomac River basin is eroding on average at 29.6 ± 14.1 Mg km–2 yr–1 (11 ± 5.2 m m.y.–1 assuming a rock density of 2700 kg m–3)—a rate consistent with other estimates in the mid-Atlantic region. 10Bei erosion rates correlate with basin latitude, suggesting that periglacial weathering increased with proximity to the former Laurentide Ice Sheet margin. Considering the 10Bei-derived erosion rate as a sediment flux over millennia, rates of sediment delivery from the Potomac River to Chesapeake Bay are up to ∼5× lower than contemporary sediment yields implying modern land-use practices have accelerated erosion and sediment transport over background rates. However, 10Bei erosion rate data suggest that regulatory benchmark levels used to manage sediment export from the Potomac River basin to Chesapeake Bay are set appropriately to reduce sedimentation and restore the Bay’s ecological health. The mean of 56 10Bem/9Bereac-derived denudation rates (40.0 ± 21.7 Mg km–2 yr–1) is higher than, but statistically indistinguishable from, the mean 10Bei erosion rate (29.6 ± 14.1 Mg km–2 yr–1; p = 0.003). However, when considered basin by basin, 10Bem/9Bereac-determined denudation rates are only weakly correlated (R2 = 0.208; p 1, suggesting that 10Bem is being retained and sediment is being stored within the Potomac River basin. The Appalachian Plateau is the only physiographic province where sediment export dominates, likely as the result of ongoing relief growth in catchments draining the Appalachian Mountain divide. 10Bem concentrations measured in the 150 k.y. Hybla Valley sediment core, taken from the lower Potomac River basin, suggest that 10Bem and sediment are preferentially stored in the catchment when vegetation proxies for climate suggest warmer conditions prevailed. 10Bem and sediment are exported when vegetation proxies for climate suggest conditions are colder, perhaps a reflection of periglacial activity or changes in storm frequency and/or magnitude over glacial-interglacial cycles. GeoRef Subject alluvium Appalachians Central Appalachians Eastern U.S. alkaline earth metals clastic sediments Be-10/Be-9 beryllium North America Potomac River basin geomorphology isotopes isotope ratios metals sediments radioactive isotopes sand stable isotopes United State

Dynamic water quality modelling and uncertainty analysis of phytoplankton and nutrient cycles for the upper South Saskatchewan River

The surface water quality of the upper South Saskatchewan River was modelled using Water Quality Analysis Simulation Program (WASP) 7.52. Model calibration and validation were based on samples taken from four long-term water quality stations during the period 2007–2009. Parametric sensitivities in winter and summer were examined using root mean square error (RMSE) and relative entropy. The calibration and validation results show good agreement between model prediction and observed data. The two sensitivity methods confirmed pronounced parametric sensitivity to model state variables in summer compared to winter. Of the 24 parameters examined, dissolved oxygen (DO) and ammonia (NH3-N) are the most influenced variables in summer. Instream kinetic processes including nitrification, nutrient uptake by algae and algae respiration induce a higher sensitivity on DO in summer than in winter. Moreover, in summer, soluble reactive phosphorus (SRP) and chlorophyll-a (Chla) variables are more sensitive to algal processes (nutrient uptake and algae death). In winter however, there exists some degree of sensitivity of algal processes (algae respiration and nutrient uptake) to DO and NH3-N. Results of this study provide information on the state of the river water quality which impacts Lake Diefenbaker and the need for additional continuous monitoring in the river. The results of the sensitivity analysis also provide guidance on most sensitive parameters and kinetic processes that affect eutrophication for preliminary surface water quality modelling studies in cold regions

Identifying Malignant Pleural Effusion by A Cancer Ratio (Serum LDH: Pleural Fluid ADA Ratio)

AIM: We studied the diagnostic potential of serum lactate dehydrogenase (LDH) in malignant pleural effusion. METHODS: Retrospective analysis of patients hospitalized with exudative pleural effusion in 2013. RESULTS: Serum LDH and serum LDH: pleural fluid ADA ratio was significantly higher in cancer patients presenting with exudative pleural effusion. In multivariate logistic regression analysis, pleural fluid ADA was negatively correlated 0.62 (0.45–0.85, p = 0.003) with malignancy, whereas serum LDH 1.02 (1.0–1.03, p = 0.004) and serum LDH: pleural fluid ADA ratio 0.94 (0.99–1.0, p = 0.04) was correlated positively with malignant pleural effusion. For serum LDH: pleural fluid ADA ratio, a cut-off level of >20 showed sensitivity, specificity of 0.98 (95 % CI 0.92–0.99) and 0.94 (95 % CI 0.83–0.98), respectively. The positive likelihood ratio was 32.6 (95 % CI 10.7–99.6), while the negative likelihood ratio at this cut-off was 0.03 (95 % CI 0.01–0.15). CONCLUSION: Higher serum LDH and serum LDH: pleural fluid ADA ratio in patients presenting with exudative pleural effusion can distinguish between malignant and non-malignant effusion on the first day of hospitalization. The cut-off level for serum LDH: pleural fluid ADA ratio of >20 is highly predictive of malignancy in patients with exudative pleural effusion (whether lymphocytic or neutrophilic) with high sensitivity and specificity