Delicate seafloor landforms reveal past Antarctic grounding-line retreat of kilometers per year.

A suite of grounding-line landforms on the Antarctic seafloor, imaged at submeter horizontal resolution from an autonomous underwater vehicle, enables calculation of ice sheet retreat rates from a complex of grounding-zone wedges on the Larsen continental shelf, western Weddell Sea. The landforms are delicate sets of up to 90 ridges, 10 kilometers per year) are inferred during regional deglaciation of the Larsen shelf. If repeated today, such rapid mass loss to the ocean would have clear implications for increasing the rate of global sea level rise

Поверхностные скорости и айсберговый сток ледникового купола Академии Наук на Северной Земле

We have determined the ice-surface velocities of the Academy of Sciences Ice Cap, Severnaya Zemlya, Russian Arctic, during the period November 2016 – November 2017, using intensity offset-tracking of Sentinel-1 synthetic-aperture radar images. We used the average of 54 pairs of weekly velocities (with both images in each pair separated by a12-day period) to estimate the mean annual ice discharge from the ice cap. We got an average ice discharge for 2016–2017 of 1,93±0,12 Gt a−1, which is equivalent to −0,35±0,02 m w.e. a−1 over the whole area of the ice cap. The difference from an estimate of ~1,4 Gt a−1 for 2003–2009 can be attributed to the initiation of ice-stream flow in Basin BC sometime between 2002 and 2016. Since the front position changes between both periods have been negligible, ice discharge is equivalent to calving flux. We compare our results for calving flux with those of previous studies and analyse the possible drivers of the changes observed along the last three decades. Since these changes do not appear to have responded to environmental changes, we conclude that the observed changes are likely driven by the intrinsic characteristics of the ice cap governing tidewater glacier dynamics.По 54 парам космических снимков Sentinel‐1, сделанных с ноября 2016 г. по ноябрь 2017 г., определены скорости движения ледникового купола Академии Наук на Северной Земле. На этой основе оценён среднегодовой расход льда в море этого купола (1,93±0,12 Гт/год), установлены основные пути стока льда, проведено сравнение с прежними оценками

Unnatural Deaths in South African Platinum Miners, 1992-2008

Background: The mortality rate from unnatural deaths for South Africa is nearly double the world average. Reliable data are limited by inaccurate and incomplete ascertainment of specific causes of unnatural death. This study describes trends in causes of unnatural death between 1992 and 2008 in a cohort of South African miners.Methodology/Principal Findings: The study used routinely-collected retrospective data with cause of death determined from multiple sources including the mine's human resources database, medical records, death registration, and autopsy. Cause-specific mortality rates and Poisson regression coefficients were calculated by calendar year and age group. The cohort included 40,043 men. One quarter of all 2937 deaths were from unnatural causes (n = 805). Causes of unnatural deaths were road traffic accidents 38% (109/100,000 py), homicides 30% (88/100,000 py), occupational injuries 17% (50/100,000 py), suicides 8% (24/100,000 py), and other accidents 6% (19/100,000 py). Rates of unnatural deaths declined by 2% (95% CI -4%,-1%) per year over the study period, driven by declining rates of road traffic and other accidents. The rate of occupational injury mortality did not change significantly over time (-2% per year, 95% CI -5%,+ 2%). Unnatural deaths were less frequent in this cohort of workers than in the South African population (IRR 0.89, 95% CI 0.82-0.95), particularly homicides (IRR 0.48, 95% CI 0.42-0.55).Conclusions/Significance: Unnatural deaths were a common cause of preventable and premature death in this cohort of miners. While unnatural death rates declined between 1992 and 2008, occupational fatalities remained at a high level. Evidence-based prevention strategies to address these avoidable deaths are urgently needed

EB Ford revisited: assessing the long-term stability of wing-spot patterns and population genetic structure of the meadow brown butterfly on the Isles of Scilly

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Data files of wing spot sizes and AFLP genotypes available from the Dryad Digital Repository: http://dx.doi.org/10.5061/dryad.j7v42.Understanding selection in the wild remains a major aim of evolutionary ecology and work by Ford and colleagues on the meadow brown butterfly Maniola jurtina did much to ignite this agenda. A great deal of their work was conducted during the 1950s on the Isles of Scilly. They documented island-specific wing-spot patterns that remained consistent over about a decade, but patterns on some islands changed after environmental perturbation. It was suggested that these wing-spot patterns reflected island-specific selection and that there was little migration between islands. However, genetic studies to test the underlying assumption of restricted migration are lacking and it is also unknown whether the originally described wing-spot patterns have persisted over time. We therefore collected female butterflies from five of Ford's original study locations, including three large islands (St Mary's, St Martin's and Tresco) and two small islands (Tean and St Helen's). Wing-spot patterns had not changed appreciably over time on three of the islands (two large and one small), but were significantly different on the other two. Furthermore, analysis of 176 amplified fragment length polymorphisms revealed significant genome-wide differentiation among the five islands. Our findings are consistent with Ford's conclusions that despite the close proximity of these islands, there is restricted gene flow among them.Heredity advance online publication, 2 November 2016; doi:10.1038/hdy.2016.94.We thank the Genetics Society for a fieldwork grant (to DJH) that funded the collection trip and DJH thanks Mike Johnson for sparking interest in this area. SWB is supported by the Australian Research Council and a Ramsay Fellowship, NW by a Royal Society Wolfson Fellowship and NERC and DJH by the Leverhulme Trust

A tidewater glacier landform assemblage in Belcher Inlet, Canadian Arctic

Belcher Glacier, a 35 km-long tidewater outlet glacier of the 12,000 km² ice cap on Devon Island (Dowdeswell et al. 2004), is one of the fastest-flowing glaciers in the Canadian Arctic (Van Wychen et al. 2014) (Fig. 1). Belcher Glacier and neighbouring Fitzroy Glacier to the southeast account for about 55% of the iceberg calving loss from the Devon Ice Cap (Van Wychen et al. 2014). The terminus of Belcher Glacier remained relatively stable between the 1960s (light blue dashed line in Fig. 1a) and 2000 (Landsat 7 satellite image in Fig. 1a). In contrast, the unnamed glacier immediately to the north retreated 2 km during this period (Fig. 1a). Belcher Glacier and the unnamed glacier retreated around 500 m and 250 m, respectively, between 2000 and 2014 (dark blue dashed line in Fig. 1a). The bed topography of Belcher Glacier, which is around 250 m below sea level at the present-day glacier margin (Fig. 1c) and remains below sea level in the lower 11 km of the glacier, suggests that its terminus region may become unstable in the event of future retreat. Seafloor mapping of Belcher Inlet beyond the termini of Belcher Glacier and the unnamed glacier (Fig. 1a), together with sub-bottom profiling, provide information about the dynamic behaviour of tidewater glaciers.This is the author accepted manuscript. The final version is available from Geological Society of London via https://doi.org/10.1144/M46.14

Scott Polar Research Institute Arctic Airborne Radio-Echo Sounding Datasets: Canadian Arctic 2000

This data set contains radar sounder profiles from the SPRI 100 MHz ice-penetrating radar instrument over Devon and Ellesmere islands in the Canadian Arctic (CA). Along with the radar profile data, the archive includes derived and ancillary data, plus software code produced for acquisition and working up of data. The data were collected under funding from a UK Natural Environment Research Council (NERC) grant (GR3/12469) to Prof. J. A. Dowdeswell. Please consult the 'MetadataCA2000.pdf' file for a detailed description of the dataset and its contents.Funding: The collection of these data was funded by NERC grant GR3/12469 to J.A. Dowdeswell, as well as by grants from the Meteorological Service of Canada (CRYSYS program) to M.J. Sharp. Further funding (to J.A. Dowdeswell) for development of the dataset was provided by the NERC Centre for Polar Observation and Modelling, UK, and the EU SPICE Project

Large-scale sedimentation on the glacier-influenced polar North Atlantic Margins: Long-range side-scan sonar evidence

Long-range side-scan sonar (GLORIA) imagery of over 600,000 km² of the Polar North Atlantic provides a large-scale view of sedimentation patterns on this glacier-influenced continental margin. High-latitude margins are influenced strongly by glacial history and ice dynamics and, linked to this, the rate of sediment supply. Extensive glacial fans (up to 350,000 km³) were built up from stacked series of large debris flows transferring sediment down the continental slope. The fans were linked with high debris inputs from Quaternary glaciers at the mouths of cross-shelf troughs and deep fjords. Where ice was slower-moving, but still extended to the shelf break, large-scale slide deposits are observed. Where ice failed to cross the continental shelf during full glacials, the continental slope was sediment starved and submarine channels and smaller slides developed. A simple model for large-scale sedimentation on the glaciated continental margins of the Polar North Atlantic is presented

Timing, rates, and causes of death in a large South African tuberculosis programme.

BACKGROUND: Tuberculosis (TB) mortality remains high across sub-Saharan Africa despite integration of TB and HIV/ART programmes. To inform programme design and service delivery, we estimated mortality by time from starting TB treatment. METHODS: Routinely collected data on TB treatment, vital status, and the timing and causes of death, were linked to cardio-respiratory autopsy data, from 1995-2008, from a cohort of male platinum miners in South Africa. Records were expanded into person-months at risk (pm). RESULTS: 4162 TB episodes were registered; 3170 men were treated for the first time and 833 men underwent retreatment. Overall, 509 men died, with a case fatality of 12.2% and mortality rate of 2.0/100 pm. Mortality was highest in the first month after starting TB treatment for first (2.3/100 pm) and retreatment episodes (4.8/100 pm). When stratified by HIV status, case fatality was higher in HIV positive men not on ART (first episode 14.0%; retreatment episode 26.2%) and those on ART (12.0%; 22.0%) than men of negative or unknown HIV status (2.6%; 3.6%). Mortality was also highest in the first month for each of these groups. Mortality risk factors included older age, previous TB, HIV, pulmonary TB, and diagnostic uncertainty. The proportion of deaths attributable to TB was consistently overestimated in clinical records versus cardio-respiratory autopsy. CONCLUSIONS: Programme mortality was highest in those with HIV and during the first month of TB treatment in all groups, and many deaths were not caused by TB. Resource allocation should prioritise TB prevention and accurate earlier diagnosis, recognise the role of HIV, and ensure effective clinical care in the early stages of TB treatment