Anabranching and maximum flow efficiency in Magela Creek, northern Australia

Anabranching is the prevailing river pattern found along alluvial tracts of the world's largest rivers. Hydraulic geometry and bed material discharge are compared between single channel and anabranching reaches up to 4 times bank-full discharge in Magela Creek, northern Australia. The anabranching channels exhibit greater sediment transporting capacity per unit available stream power, i.e., maximum flow efficiency (MFE). Simple flume experiments corroborate our field results showing the flow efficiency gains associated with anabranching, and highlight the prospect of a dominant anabranch, which is found in many anabranching rivers. These results demonstrate that anabranching can constitute a stable river pattern in dynamic equilibrium under circumstances in which a continuous single channel would be unable to maintain sediment conveyance. We propose the existence of a flow efficiency continuum that embraces dynamic equilibrium and disequilibrium (vertically accreting) anabranching rivers

Long-term flood controls on semi-arid river form: evidence from the Sabie and Olifants rivers, eastern South Africa

Rivers in the Kruger National Park, eastern South Africa, are characterised by bedrock-influenced ‘macrochannels’ containing variable alluvial thicknesses and riparian vegetation assemblages. Evidence from the Sabie and Olifants rivers suggests that flows up to moderate floods (<3500 m3 s-1) tend to result in net alluviation, with sediments gradually covering the underlying bedrock. More extreme floods strip alluvium and erode bedrock, effectively exerting the primary control over long-term river morphologic development. On the Olifants River, post-flood aerial LIDAR imagery reveals that the 2012 extreme flood (~14000 m3 s-1) resulted in extensive stripping of stored alluvial sediment, exposing and eroding the underlying weathered bedrock. On the Sabie River, preliminary optically stimulated luminescence ages for remnant alluvium are all less than 1000 years, highlighting typical timescales of sediment storage. Together, these results suggest that while periods of general alluviation occur on these systems, long-term river development results from extreme flood-generated bedrock erosion

Moderate agreement between self-reported stroke and hospital-recorded stroke in two cohorts of Australian women: a validation study

Background: Conflicting findings on the validity of self-reported stroke from existing studies creates uncertainty about the appropriateness of using self-reported stroke in epidemiological research. We aimed to compare self-reported stroke against hospital-recorded stroke, and investigate reasons for disagreement. Methods: We included participants from the Australian Longitudinal Study on Women's Health born in 1921-26 (n = 1556) and 1946-51 (n = 2119), who were living in New South Wales and who returned all survey questionnaires over a defined period of time. We determined agreement between self-reported and hospitalised stroke by calculating sensitivity, specificity and kappa statistics. We investigated whether characteristics including age, education, area of residence, country of birth, language spoken at home, recent mental health at survey completion and proxy completion of questionnaire were associated with disagreement, using logistic regression analysis to obtain odds ratios (ORs) with 95% confidence intervals (CIs). Results: Agreement between self-report and hospital-recorded stroke was fair in older women (kappa 0.35, 95% CI 0.25 to 0.46) and moderate in mid-aged women (0.56, 95% CI 0.37 to 0.75). There was a high proportion with unverified self-reported stroke, partly due to: reporting of transient ischaemic attacks; strokes occurring outside the period of interest; and possible reporting of stroke-like conditions. In the older cohort, a large proportion with unverified stroke had hospital records of other cerebrovascular disease. In both cohorts, higher education was associated with agreement, whereas recent poor mental health was associated with disagreement. Conclusion: Among women who returned survey questionnaires within the period of interest, validity of self-reported stroke was fair to moderate, but is probably underestimated. Agreement between self-report and hospital-recorded stroke was associated with individual characteristics. Where clinically verified stroke data are unavailable, self-report may be a reasonable alternative method of stroke ascertainment for some epidemiological studies

A comparison of multiple luminescence chronometers at Voordrag, South Africa

A suite of 10 samples collected from an 11 m thick colluvial sequence at Voordrag, KwaZulu-Natal, South Africa, have been used to undertake a comparison of different luminescence methods. Good agreement is found between single grain quartz optically stimulated luminescence (OSL) and single grain K-feldspar post-infrared infrared-stimulated luminescence (post-IR IRSL) ages, with the exception of the basal samples where the quartz OSL signal is saturated. Multiple grain quartz OSL consistently yields ages older than single grain OSL methods. Multiple grain feldspar ages derived from the IRSL50 signal are underestimated due to anomalous fading. A previously published radiocarbon chronology yields ages that are younger than those from single grain quartz OSL and post-IR IRSL, and this is most likely due to contamination with younger carbon. Identifying the effect of saturation on the quartz OSL signal remains challenging when quartz is dated in isolation. However, using a paired quartz/feldspar dating approach is an effective way of identifying the impact of saturation on the OSL signal

Factors associated with educational mobility in mid-age Australian women

The educational mobility of mid-age women is rarely studied. We analysed the baseline socio-economic position (SEP) and health factors associated with obtaining further education in 4117 mid-age Australian women between 1996 and 2010 (aged 45–50 at baseline, 62–67 at follow-up) from a population-based study. Women either unemployed or working part-time at baseline had higher odds of a stable low and middle education over time (ORs ranging from 1.61 to 3.86) versus educational mobility. Apart from obesity, characteristics that may signal an unhealthy lifestyle in early mid-life were not useful indicators of women's future educational mobility

A pilot study of alterations in oxidized angiotensinogen and antioxidants in pre-eclamptic pregnancy

© 2020, The Author(s). The oxidation status of angiotensinogen (AGT) may have a critical role in pre-eclampsia. We used a validated, quantitative, mass spectrometry-based method to measure the oxidized and total AGT levels in plasma of pre-eclamptic women (n = 17), normotensive-matched controls (n = 17), and healthy non-pregnant women (n = 10). Measurements of plasma glutathione peroxidase (GPx) activity and serum selenium concentrations were performed as markers of circulating antioxidant capacity. Higher proportions of oxidized AGT in plasma from pre-eclamptic women compared to matched normotensive pregnant controls (P = 0.006), whilst maintaining a similar total plasma AGT concentration were found. In the pre-eclamptic group, blood pressure were correlated with the proportion of oxidized AGT; no such correlation was seen in the normotensive pregnant women. Plasma GPx was inversely correlated with oxidized AGT, and there was an inverse association between serum selenium concentration and the proportion of oxidized AGT. This is the first time that oxidized AGT in human plasma has been linked directly to antioxidant status, providing a mechanism for the enhanced oxidative stress in pre-eclampsia. We now provide pathophysiological evidence that the conversion of the reduced form of AGT to its more active oxidized form is associated with inadequate antioxidant status and could indeed contribute to the hypertension of pre-eclampsia

Effects of vegetation on bacterial communities, carbon and nitrogen in dryland soil surfaces: implications for shrub encroachment in the southwest Kalahari

Shrub encroachment is occurring in many of the world's drylands, but its impacts on ecosystem structure and function are still poorly understood. In particular, it remains unclear how shrub encroachment affects dryland soil surfaces, including biological soil crust (biocrust) communities. In this study, soil surfaces (0–1 cm depth) were sampled from areas of Grewia flava shrubs and Eragrostis lehmanniana and Schmidtia kalahariensis grasses in the southwest Kalahari during two different seasons (March and November). Our hypothesis is that the presence of different vegetation cover types (shrubs versus grasses) alters the microbial composition of soil surfaces owing to their contrasting microenvironments. The results showed that more significant differences in microclimate (light, soil surface temperatures) and soil surface microbial communities were observed between shrubs and grasses than between sampling seasons. Based on high-throughput 16S rRNA gene sequencing, our findings showed that approximately one third (33.5%) of the operational taxonomic units (OTUs) occurred exclusively in soil surfaces beneath shrubs. Soil surfaces with biocrusts in grass areas were dominated by the cyanobacteria Microcoleus steenstrupii, whereas the soil surfaces beneath shrubs were dominated by the proteobacteria Microvirga flocculans. Soil surfaces beneath shrubs are associated with reduced cyanobacterial abundance but have higher total carbon and total nitrogen contents compared to biocrusts in grass areas. These findings infer changes in the relative contributions from different sources of carbon and nitrogen (e.g. cyanobacterial and non-cyanobacterial fixation, plant litter, animal activity). The distinctive microbial composition and higher carbon and nitrogen contents in soil surfaces beneath shrubs may provide a positive feedback mechanism promoting shrub encroachment, which helps to explain why the phenomenon is commonly observed to be irreversible.This study was kindly supported by the European Union's Horizon 2020 Research and Innovation Programme under a Marie Skłodowska-Curie Grant (No. 663830), by the National Natural Science Foundation of China (No. 31670456), and by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA17010502)

Simulating the influences of groundwater on regional geomorphology using a distributed, dynamic, landscape evolution modelling platform

A dynamic landscape evolution modelling platform (CLiDE) is presented that allows a variety of Earth system interactions to be explored under differing environmental forcing factors. Representation of distributed surface and subsurface hydrology within CLiDE is suited to simulation at sub-annual to centennial time-scales. In this study the hydrological components of CLiDE are evaluated against analytical solutions and recorded datasets. The impact of differing groundwater regimes on sediment discharge is examined for a simple, idealised catchment, Sediment discharge is found to be a function of the evolving catchment morphology. Application of CLiDE to the upper Eden Valley catchment, UK, suggests the addition of baseflow-return from groundwater into the fluvial system modifies the total catchment sediment discharge and the spatio-temporal distribution of sediment fluxes during storm events. The occurrence of a storm following a period of appreciable antecedent rainfall is found to increase simulated sediment fluxes

The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods

A recent workshop entitled The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods was held in Paris in December 2010, sponsored by the French National Centre for Scientific Research (CNRS) and by the journal Human Biology. This workshop was intended to foster a debate on questions related to the family names and to compare different multidisciplinary approaches involving geneticists, historians, geographers, sociologists and social anthropologists. This collective paper presents a collection of selected communications