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Deep-water ‘stable’ subglacial lakes likely contain microbial life adapted in isolation to extreme environmental conditions. How water is supplied into a subglacial lake, and how water outflows, is important for understanding these conditions. Isochronal radio-echo layers have been used to infer where melting occurs above Lake Vostok and Lake Concordia in East Antarctica but have not been used more widely. We examine englacial layers above and around Lake Ellsworth, West Antarctica, to establish where the ice sheet is ‘drawn down’ towards the bed and, thus, experiences melting. Layer drawdown is focused over and around the northwest parts of the lake as ice, flowing obliquely to the lake axis becomes afloat. Drawdown can be explained by a combination of basal melting and the Weertman effect, at the transition from grounded to floating ice. We evaluate the importance of these processes on englacial layering over Lake Ellsworth and discuss implications for water circulation and sediment deposition. We report evidence of a second subglacial lake near the head of the hydrological catchment and present a new high-resolution bed DEM and hydropotential model of the lake outlet zone. These observations provide insight into the connectivity between Lake Ellsworth and the wider subglacial hydrological system.
Basal units – visibly distinct englacial structures near the ice-bed interface – warrant investigation for a number of reasons. Many are of unknown composition and origin, characteristics that could provide substantial insight into subglacial processes and ice-sheet history. Their significance, moreover, is not limited to near-bed depths; these units appear to dramatically influence the flow of surrounding ice. In order to enable improved characterization of these features, we develop and apply an algorithm that allows for the automatic detection of basal units. We use a tunable layer-optimized SAR processor to distinguish these structures from the bed, isochronous englacial layers and the ice-sheet surface, presenting a conceptual framework for the use of radio-echo character in the identification of ice-sheet features. We also outline a method by which our processor could be used to place observational constraints on basal units’ configuration, composition and provenance.
The invasive alien Scolytus schevyrewi Semenov (Coleoptera: Curculionidae: Scolytinae) was detected in Saskatchewan and Manitoba, Canada, in 2007. Because S. schevyrewi is a potential vector of the Dutch elm disease pathogen (Ophiostomanovo-ulmi Brasier; Fungi: Ophiostomataceae), the natural history of the beetle was studied from 2009 to 2012 in the two provinces, where the disease is managed to protect Ulmus americana Linnaeus (Ulmaceae). Typically, healthy trees become infected when their xylem is contacted during feeding by spore-bearing scolytine adults that have flown from a diseased tree; adults emerging from brood galleries in diseased trees frequently carry spores. We caught flying S. schevyrewi adults from May to October; adults were weakly attracted to healthy Ulmus Linnaeus but were strongly attracted to Ulmus pumila Linnaeus stressed by girdling. Scolytus schevrewi colonised and completed development in girdled trees and trap logs of U. pumila. In contrast to other studies, U. americana – the major source of pathogen spores in the area – was never colonised as a brood host. Our results suggest that S. schevyrewi will primarily use U. pumila, which, in Manitoba and Saskatchewan, seldom exhibits symptoms of Dutch elm disease. Thus, arrival of S. schevyrewi does not appear to require changes to Dutch elm disease management programmes.
Ramparted depressions (doughnut-shaped debris-cored ridges with peat- and/or sediment-filled central basins) are commonly perceived to represent the relict collapsed forms of permafrost ground-ice mounds (i.e. pingos or lithalsas). In Wales, UK, ramparted depressions of Late Pleistocene age have been widely attributed to permafrost-related processes. However, a variety of alternative glacial origins for these enigmatic landforms are also consistent with the available geological and geomorphological evidence, although previous studies have barely considered such alternative processes of formation. From detailed geophysical, sedimentological and remote-sensing studies at two field sites, we demonstrate that: (i) the wastage of stagnating glacier ice is a viable alternative explanation for the formation of ramparted depressions in Wales; (ii) the glacial geomorphology and geology of these landforms is analogous to supraglacial and subglacial landforms from the last Laurentide and Fennoscandian ice sheets; (iii) these landforms have significant potential for characterising the nature of deglaciation around the margins of the Irish Sea during the last glacial cycle, and may record evidence for the overextension and stagnation of the south-eastern margin of the Irish Sea Ice Stream; and (iv) investigations of ramparted depressions within formerly glaciated terrains must consider both glacial and periglacial mechanisms of formation.
Numerical ice-sheet models are commonly matched to surface ice velocities from InSAR measurements by modifying basal drag, allowing the flow and form of the ice sheet to be simulated. Geophysical measurements of the bed are rarely used to examine if this modification is realistic, however. Here, we examine radio-echo sounding (RES) data from the Weddell Sea sector of West Antarctica to investigate how the output from a well-established ice-sheet model compares with measurements of the basal environment. We know the Weddell Sea sector contains the Institute, Möller and Foundation ice streams, each with distinct basal characteristics: Institute Ice Stream lies partly over wet unconsolidated sediments, where basal drag is very low; Möller Ice Stream lies on relatively rough bed, where basal drag is likely larger; and Foundation Ice Stream is controlled by a deep subglacial trough with flow-aligned bedrock landforms and smooth unconsolidated sediments. In general, the ice-sheet model represents each ice-stream system well. We also find that ice velocities do not match perfectly in some locations, and that adjustment of the boundaries of low basal drag, to reflect RES evidence, should improve model performance. Our work showcases the usefulness of RES in calibrating ice-sheet model results with observations of the bed.
Tree-ring reconstructions of temperature often target trees at altitudinal or latitudinal tree line where annual growth is broadly expected to be limited by and respond to temperature variability. Based on this principal, regions with sparse tree line would seem to be restricted in their potential to reconstruct past temperatures. In the northeastern United States, there are only two published temperature reconstructions. Previous work in the region reconstructing moisture availability, however, has shown that using a greater diversity of species can improve reconstruction model skill. Here, we use a network of 228 tree-ring records composed of 29 species to test the hypothesis that an increase in species diversity among the pool of predictors improves reconstructions of past temperatures. Chamaecyparis thyoides alone explained 31% of the variability in observed cool-season minimum temperatures, but a multispecies model increased the explained variance to 44%. Liriodendron tulipifera, a species not previously used for temperature reconstructions, explained a similar amount of variance as Chamaecyparis thyoides (12.9% and 20.8%, respectively). Increasing the species diversity of tree proxies has the potential for improving reconstruction of paleotemperatures in regions lacking latitudinal or elevational tree lines provided that long-lived hardwood records can be located.
Emergency department (ED) access block, the inability to provide timely care for high acuity patients, is the leading safety concern in First World EDs. The main cause of ED access block is hospital access block with prolonged boarding of inpatients in emergency stretchers. Cumulative emergency access gap, the product of the number of arriving high acuity patients and their average delay to reach a care space, is a novel access measure that provides a facility-level estimate of total emergency care delays. Many health leaders believe these delays are too large to be solved without substantial increases in hospital capacity. Our objective was to quantify cumulative emergency access blocks (the problem) as a fraction of inpatient capacity (the potential solution) at a large sample of Canadian hospitals.
In this cross-sectional study, we collated 2015 administrative data from 25 Canadian hospitals summarizing patient inflow and delays to ED care space. Cumulative access gap for high acuity patients was calculated by multiplying the number of Canadian Triage Acuity Scale (CTAS) 1-3 patients by their average delay to reach a care space. We compared cumulative ED access gap to available inpatient bed hours to estimate fractional access gap.
Study sites included 16 tertiary and 9 community EDs in 12 cities, representing 1.79 million patient visits. Median ED census (interquartile range) was 66,300 visits per year (58,700-80,600). High acuity patients accounted for 70.7% of visits (60.9%-79.0%). The mean (SD) cumulative ED access gap was 46,000 stretcher hours per site per year (± 19,900), which was 1.14% (± 0.45%) of inpatient capacity.
ED access gaps are large and jeopardize care for high acuity patients, but they are small relative to hospital operating capacity. If access block were viewed as a “whole hospital” problem, capacity or efficiency improvements in the range of 1% to 3% could profoundly mitigate emergency care delays.
The increasingly negative mass balance of the Greenland ice sheet (GrIS) over the last ~25 years has been associated with enhanced surface melt and increased ice loss from marine-terminating outlet glaciers. Accelerated retreat during 2000–2010 was concentrated in the southeast and northwest sectors of the ice sheet; however, there was considerable spatial and temporal variability in the timing and magnitude of retreat both within and between these regions. This behaviour has yet to be quantified and compared for all glaciers in both regions. Furthermore, it is unclear whether retreat has continued after 2010 in the northwest, and whether the documented slowdown in the southeast post-2005 has been sustained. Here, we compare spatial and temporal patterns of frontal change in the northwest and southeast GrIS, for the period 2000–2015. Our results show near-ubiquitous retreat of outlet glaciers across both regions for the study period; however, the timing and magnitude of inter-annual frontal position change is largely asynchronous. We also find that since 2010, there is continued terminus retreat in the northwest, which contrasts with considerable inter-annual variability in the southeast. Analysis of the role of glacier-specific factors demonstrates that fjord and bed geometry are important controls on the timing and magnitude of glacier retreat.
The Zika virus was largely unknown to many health care systems before the outbreak of 2015. The unique public health threat posed by the Zika virus and the evolving understanding of its pathology required continuous communication between a health care delivery system and a local public health department. By leveraging an existing relationship, NYC Health+Hospitals worked closely with New York City Department of Health and Mental Hygiene to ensure that Zika-related processes and procedures within NYC Health+Hospitals facilities aligned with the most current Zika virus guidance. Support given by the public health department included prenatal clinical and laboratory support and the sharing of data on NYC Health+Hospitals Zika virus screening and testing rates, thus enabling this health care delivery system to make informed decisions and practices. The close coordination, collaboration, and communication between the health care delivery system and the local public health department examined in this article demonstrate the importance of working together to combat a complex public health emergency and how this relationship can serve as a guide for other jurisdictions to optimize collaboration between external partners during major outbreaks, emerging threats, and disasters that affect public health. (Disaster Med Public Health Preparedness. 2018;12:689-691)
A diverse millipede (diplopod) fauna has been recovered from the earliest Carboniferous (Tournaisian) Ballagan Formation of the Scottish Borders, discovered by the late Stan Wood. The material is generally fragmentary; however, six different taxa are present based on seven specimens. Only one displays enough characters for formal description and is named Woodesmus sheari Ross, Edgecombe & Clark gen. & sp. nov. The absence of paranota justifies the erection of Woodesmidae fam. nov. within the Archipolypoda. The diverse fauna supports the theory that an apparent lack of terrestrial animal fossils from ‘Romer's Gap' was due to a lack of collecting and suitable deposits, rather than to low oxygen levels as previously suggested.
Two new species of Schramocaris from the Viséan, Lower Carboniferous of Scotland and eastern Canada extend the range and distribution of this crustacean along the northwestern coast of the Rheic Ocean. New species from Glencartholm, southern Scotland and Upperton, New Brunswick, Canada represents the first recognised occurrence of this genus in Scotland and Canada. The Scottish species is here named S. clarksoni; it lacks the rugosity of the carinae of Schramocaris gilljonesorum, but has the same relative position of the carinae, as well as similar characteristics of the pleon, such as the relative lengths of the somites and the shape of the telson. The Canadian species is named Schramocaris matthewi on the basis of the papillations on the cuticle and robust second carinae of the carapace. The deposits at both these localities are that of a shallow marine argillaceous environment, although the Glencartholm deposit contains more lime. Schramocaris has previously only been known from the Avon Group (Hastarian) of the Forest of Dean, England.
The Institute Ice Stream (IIS) rests on a reverse-sloping bed, extending >150 km upstream into the ~1.8 km deep Robin Subglacial Basin, placing it at the threshold of marine ice-sheet instability. Understanding IIS vulnerability has focused on the effect of grounding-line melting, which is forecast to increase significantly this century. Changes to ice-flow dynamics are also important to IIS stability, yet little is known about them. Here we reveal that the trunk of the IIS occurs downstream of the intersection of three discrete subglacial features; a large ‘active’ subglacial lake, a newly-discovered sharp transition to a zone of weak basal sediments and a major tectonic rift. The border of IIS trunk flow is confined by the sediment on one side, and by a transition between basal melting and freezing at the border with the Bungenstock Ice Rise. By showing how basal sediment and water dictate present-day flow of IIS, we reveal that ice-sheet stability here is dependent on this unusual arrangement.
In 1976, David Sugden and Brian John developed a classification for Antarctic landscapes of glacial erosion based upon exposed and eroded coastal topography, providing insight into the past glacial dynamics of the Antarctic ice sheets. We extend this classification to cover the continental interior of Antarctica by analysing the hypsometry of the subglacial landscape using a recently released dataset of bed topography (BEDMAP2). We used the existing classification as a basis for first developing a low-resolution description of landscape evolution under the ice sheet before building a more detailed classification of patterns of glacial erosion. Our key finding is that a more widespread distribution of ancient, preserved alpine landscapes may survive beneath the Antarctic ice sheets than has been previously recognized. Furthermore, the findings suggest that landscapes of selective erosion exist further inland than might be expected, and may reflect the presence of thinner, less extensive ice in the past. Much of the selective nature of erosion may be controlled by pre-glacial topography, and especially by the large-scale tectonic structure and fluvial valley network. The hypotheses of landscape evolution presented here can be tested by future surveys of the Antarctic ice sheet bed.
In the early hours of 25 December 2012, an attempt to explore Subglacial Lake Ellsworth, West Antarctica, using a specially designed hot-water drill, was halted. This UK project, involving several universities, the British Antarctic Survey and the National Oceanography Centre, had been in planning for 10 years. The project developed a full blueprint for subglacial lakes research, involving access to the subglacial environment through deep drilling, direct measurement and sampling of water and sediment by the construction of a probe and sediment corer, and environmental protocols to ensure cleanliness in line with international agreements on stewardship and protection of subglacial systems. Drilling was ceased after the main borehole failed to link with a subsurface cavity of water, built up over ∽40 hours. Without this link, insufficient water was available to continue drilling downwards to the lake, ∽3000 m beneath the surface. On return to the UK, an external review of the programme was undertaken to formally assess the reasons for the fieldwork failure, and to make recommendations on the modifications necessary for success. From this review, the Lake Ellsworth programme formulated a pathway along which a second attempt to explore the lake can be developed. Here details of the Lake Ellsworth field experiment, the circumstances that led to its failure and the corrections required are presented. Hot-water drilling is still regarded as the only feasible scheme for assuring clean access to the subglacial environment. The lessons learned from the Lake Ellsworth experience are substantial, however, and demonstrate that considerable technological and methodological advances are necessary for successful future research on subglacial lakes beneath thick (>2 km) ice.
Prior-approval antimicrobial stewardship programs (ASPs) improve patient outcomes and decrease antimicrobial resistance. These benefits would be limited if physicians circumvented ASP efforts. We evaluated whether prescribers wait until after the prior-approval period to order restricted antimicrobial therapy that is in conflict with guidelines or unnecessary.
A cross-sectional study design and a retrospective cohort study design.
A tertiary care, academic medical center with a prior-approval ASP that was active between 8 AM and 10 PM.
We evaluated whether there was an increase in the proportion of orders for antimicrobial therapy that involve restricted (vs nonrestricted) antimicrobials during the first hour that the ASP is inactive (ie, the first hour that prior approval is not required), compared with the remainder of the day. We also evaluated whether restricted antimicrobial therapy ordered during this first hour is less likely to be continued when the ASP becomes active the next day, compared with that ordered during the preceding hour.
A greater proportion of the antimicrobial therapy orders placed between 10:00 PM and 10:59 PM were for restricted agents, compared with orders placed during other periods (57.0% vs 49.9%; P = .02). Surgical patients for whom antimicrobial therapy orders were placed between 10:00 PM and 10:59 PM were less likely to have that antimicrobial therapy continued, compared with patients whose therapy was ordered between 9:00 PM and 9:59 PM (60.0% vs 98.1%; P <.001). Nonsurgical patients whose therapy orders were placed between 10:00PM and 10:59 PM were also less likely to have the ordered antimicrobial therapy continued, compared with patients whose therapy was ordered between 9:00 PM and 9:59 PM (70.8% vs 84.2%; P = .01).
Physicians avoid having to obtain prior approval for therapy involving restricted antimicrobials by waiting until restrictions are no longer active to place orders. Compared with restricted antimicrobial therapy ordered when the ASP is active, these courses of therapy are less often continued by the ASP, suggesting that they are more likely to be in conflict with guidelines or unnecessary.
The objective of this paper is to describe variations in the different models of out of hours general medical services and identify explanations for variation and the possible influence on patient satisfaction and service costs. A cross-sectional survey of all models of out of hours care was undertaken, including co-operatives, deputizing services, practice rotas and rural general practitioners doing their own cover. Fifteen sites were chosen representing 10 models of care, for more detailed case study; 65 semistructured interviews with key informants were conducted within the case study sites. A postal patient satisfaction questionnaire and an economic analysis were also carried out. Out of hours organizations have developed in response to a complex mix of the population served, geography, resources available and political expediency, leading to considerable structural heterogeneity, even within co-operatives. There was little evidence of formal integration with other services. Only the largest co-operatives showed any evidence of utilizing guidelines/protocols or of providing formal staff training. There were clear differences in the structure of out of hours care in urban and rural areas. Increasing the use of centralized call handling and triage will not address the needs of rural GPs, who would still be required to be available for work. Neither patient satisfaction nor costs varied bymodel of service provision. The English out of hours reviewhas outlined an integrated model of service provision with consistent standards within an accountability framework. It would appear that only the largest organizations will be in a position to address these standards and that they are likely to be inappropriate to the needs of GPs in rural areas.
Little is known about the psychological health or treatment experiences of those who have left the British armed forces.
To describe the frequency and associations of common mental disorders and help-seeking behaviours in a representative sample of UK veterans at high risk of mental health problems.
A cross-sectional telephone survey of 496 ‘vulnerable’ ex-service personnel selected from an existing epidemiological military cohort.
The response rate was 64%; 44% of these had a psychiatric diagnosis, most commonly depression. Those with a diagnosis were more likely to be of lower rank and divorced or separated. Just over half of those with self-reported mental health problems were currently seeking help, most from their general practitioners. Most help-seekers received treatment, usually medication; 28% were in touch with a service charity and 4% were receiving cognitive-behavioural therapy.
Depression is more common than post-traumatic stress disorder in UK ex-service personnel. Only about half of those who have a diagnosis are seeking help currently, and few see specialists.