Accumulation at South Pole: Comparison of two 900-year records

This is the published version, also available here: http://dx.doi.org/10.1029/1999JD900501.Two 900-year records of annual accumulation at South Pole are compared to evaluate the origin and significance of observed variations. Despite difficulties establishing absolute timescales, due to problems identifying annual layer markers, the two records can be correlated with confidence after moderate smoothing. This correlation shows that over the time period considered (1050–1956 A.D.) no climatically significant changes in accumulation occurred. Instead, fluctuations preserved in the two cores reflect spatial variations in snow accumulation, associated with nonuniform deposition induced by surface relief on the scale of several kilometers

Clean Low-Biomass Procedures and Their Application to Ancient Ice Core Microorganisms

Microorganisms in glacier ice provide tens to hundreds of thousands of years archive for a changing climate and microbial responses to it. Analyzing ancient ice is impeded by technical issues, including limited ice, low biomass, and contamination. While many approaches have been evaluated and advanced to remove contaminants on ice core surfaces, few studies leverage modern sequencing to establish in silico decontamination protocols for glacier ice. Here we sought to apply such “clean” sampling techniques with in silico decontamination approaches used elsewhere to investigate microorganisms archived in ice at ~41 (D41, ~20,000 years) and ~49 m (D49, ~30,000 years) depth in an ice core (GS3) from the summit of the Guliya ice cap in the northwestern Tibetan Plateau. Four “background” controls were established – a co-processed sterile water artificial ice core, two air samples collected from the ice processing laboratories, and a blank, sterile water sample – and used to assess contaminant microbial diversity and abundances. Amplicon sequencing revealed 29 microbial genera in these controls, but quantitative PCR showed that the controls contained about 50–100-times less 16S DNA than the glacial ice samples. As in prior work, we interpreted these low-abundance taxa in controls as “contaminants” and proportionally removed them in silico from the GS3 ice amplicon data. Because of the low biomass in the controls, we also compared prokaryotic 16S DNA amplicons from pre-amplified (by re-conditioning PCR) and standard amplicon sequencing, and found the resulting microbial profiles to be repeatable and nearly identical. Ecologically, the contaminant-controlled ice microbial profiles revealed significantly different microorganisms across the two depths in the GS3 ice core, which is consistent with changing climate, as reported for other glacier ice samples. Many GS3 ice core genera, including Methylobacterium, Sphingomonas, Flavobacterium, Janthinobacterium, Polaromonas, and Rhodobacter, were also abundant in previously studied ice cores, which suggests wide distribution across glacier environments. Together these findings help further establish “clean” procedures for studying low-biomass ice microbial communities and contribute to a baseline understanding of microorganisms archived in glacier ice

Changes in the firn structure of the western Greenland Ice Sheet caused by recent warming

Atmospheric warming over the Greenland Ice Sheet during the last 2 decades has increased the amount of surface meltwater production, resulting in the migration of melt and percolation regimes to higher altitudes and an increase in the amount of ice content from refrozen meltwater found in the firn above the superimposed ice zone. Here we present field and airborne radar observations of buried ice layers within the near-surface (0–20 m) firn in western Greenland, obtained from campaigns between 1998 and 2014. We find a sharp increase in firn-ice content in the form of thick widespread layers in the percolation zone, which decreases the capacity of the firn to store meltwater. The estimated total annual ice content retained in the near-surface firn in areas with positive surface mass balance west of the ice divide in Greenland reached a maximum of 74 ± 25 Gt in 2012, compared to the 1958–1999 average of 13 ± 2 Gt, while the percolation zone area more than doubled between 2003 and 2012. Increased melt and column densification resulted in surface lowering averaging −0.80 ± 0.39 m yr−1 between 1800 and 2800 m in the accumulation zone of western Greenland. Since 2007, modeled annual melt and refreezing rates in the percolation zone at elevations below 2100 m surpass the annual snowfall from the previous year, implying that mass gain in the region is retained after melt in the form of refrozen meltwater. If current melt trends over high elevation regions continue, subsequent changes in firn structure will have implications for the hydrology of the ice sheet and related abrupt seasonal densification could become increasingly significant for altimetry-derived ice sheet mass balance estimates

Evidence for specialist treatment of people with acquired brain injury in secure psychiatric services: systematic review and narrative synthesis

This is the final version. Available from NIHR Journals Library via the DOI in this recordThe protocol for this systematic review is available in ORE at http://hdl.handle.net/10871/40286Patients with acquired brain injury (ABI) may experience various physical, cognitive or emotional sequelae and are at increased risk of mental health difficulties. They may display aggressive, sexually inappropriate or disinhibited behaviour which challenges those supporting them and poses a risk to themselves or others. Such individuals may need assessment, care and/or treatment within secure settings. There is limited availability of secure placements and referral must be based on the patient meeting certain criteria. Objectives To systematically review evidence that can inform the arrangements for the specialist care of adults with ABI who may require secure psychiatric services. Data sources Seven bibliographic databases (CINAHL, HMIC, MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, PsycINFO, Social Policy & Practice, ASSIA) were searched on 27th June 2019, date-limited to 2000. Database searches were supplemented with citation searching; inspecting relevant reviews; searching ClinicalTrials.gov and WHO International Clinical Trials Registry Platform, searching relevant websites; liaising with clinical experts and affiliation searches. Review methods We sought evidence about adults with non-degenerative ABI placed in, eligible for referral to, or being assessed for eligibility for referral to secure psychiatric services in any highincome country. Eligibility for referral to secure services was based on assessment or observation of challenging behaviours. Psychometric studies of tools used in assessments were eligible for inclusion. Study selection, data extraction and quality assessment were completed independently by two reviewers. Given the heterogeneity of studies, outcomes and data, a narrative synthesis approach was used. We were interested in identifying patient, diagnostic or symptom characteristics associated with requiring care in secure settings. Findings 6297 unique titles and abstracts were screened against inclusion criteria, leading to full-text screening of 325 papers. Forty-six observational and case-control studies and one systematic review were included; however none were set in, or referred explicitly to secure settings. Thirty-eight of the primary studies evaluated patient characteristics associated with challenging behaviour. Eight primary studies and the systematic review evaluated the psychometric properties of measures used to assess challenging behaviour. Narrative synthesis indicated a highly heterogeneous set of studies providing uncertain evidence about patient characteristics which may be associated with challenging behaviours. Whilst tentative associations were found between certain patient characteristics and occurrence of challenging behaviour, the conflicting nature of this evidence reduces confidence in these findings. There was no strong evidence to recommend the use of specific patient assessment tools. Limitations We found no evidence regarding referrals to secure treatment settings and thus were not able to directly answer our research questions. Studies investigating associations between patient characteristics and challenging behaviours varied in methodological rigour and evidence was highly heterogeneous. Conclusions There is no direct evidence to support decisions about the suitable setting for the care of adults with ABI who display challenging behaviour. There is tentative evidence about patient characteristics associated with risk of challenging behaviour. Future work Primary research is needed to inform evidence-based decisions on the appropriate setting for the care of people with ABI who display challenging behaviour.National Institute for Health Research (NIHR

Surface roughness over the northern half of the Greenland Ice Sheet from airborne laser altimetry

This is the published version, also available here: http://dx.doi.org/10.1029/2008JF001067.Surface roughness, defined as the standard deviation of small-scale elevation fluctuations from the linear trend over 0.5 km, can be estimated from high-resolution airborne laser altimetry. Here we present results for the northern half of the Greenland Ice Sheet using laser data collected in May 1995. Roughness is smallest in the central region straddling the ice divide, increases in amplitude toward the coast, and appears to be correlated with slope of the ice surface. For most of the study region surface roughness is 8 cm or less (<2.5 cm water equivalent). In smaller regions associated with fast flow, larger values are found. Comparison of the size of small-scale topographic disturbances with the spatial noise estimated from five closely spaced ice cores drilled in northwest Greenland shows good agreement. Similar correspondence was found earlier using nine ice cores from the Summit region. These results indicate that the airborne laser altimeter provides an efficient platform for characterizing the statistical nature of the snow surface over large areas of the polar ice sheets

Exposure-age record of Holocene ice sheet and ice shelf change in the northeast Antarctic Peninsula

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Elevation change of the Greenland Ice Sheet due to surface mass balance and firn processes, 1960–2014

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in The Cryosphere 9 (2015): 2009-2025, doi:10.5194/tc-9-2009-2015.Observed changes in the surface elevation of the Greenland Ice Sheet are caused by ice dynamics, basal elevation change, basal melt, surface mass balance (SMB) variability, and by compaction of the overlying firn. The last two contributions are quantified here using a firn model that includes compaction, meltwater percolation, and refreezing. The model is forced with surface mass fluxes and temperature from a regional climate model for the period 1960–2014. The model results agree with observations of surface density, density profiles from 62 firn cores, and altimetric observations from regions where ice-dynamical surface height changes are likely small. In areas with strong surface melt, the firn model overestimates density. We find that the firn layer in the high interior is generally thickening slowly (1–5 cm yr−1). In the percolation and ablation areas, firn and SMB processes account for a surface elevation lowering of up to 20–50 cm yr−1. Most of this firn-induced marginal thinning is caused by an increase in melt since the mid-1990s and partly compensated by an increase in the accumulation of fresh snow around most of the ice sheet. The total firn and ice volume change between 1980 and 2014 is estimated at −3295 ± 1030 km3 due to firn and SMB changes, corresponding to an ice-sheet average thinning of 1.96 ± 0.61 m. Most of this volume decrease occurred after 1995. The computed changes in surface elevation can be used to partition altimetrically observed volume change into surface mass balance and ice-dynamically related mass changes.P. Kuipers Munneke received financial support from the Netherlands Polar Programme (NPP) of the Netherlands Institute for Scientific Research (NWO). ECMWF at Reading (UK) is acknowledged for use of the Cray supercomputing system. The J. E. Box contribution is supported by Det Frie Forskningsråd grant 4002-00234 and Geocenter Denmark

The Communist Party and the New Party

This is an Author's Accepted Manuscript of an article published in Contemporary British History, vol. 23(4), 2009, pp.477-491 copyright Taylor & Francis, available online at: http://www.tandfonline.com/doi/full/10.1080/13619460903198101The New Party was never at the centre of the concerns of the Communist Party of Great Britain (CPGB). However, the CPGB had to take a line on the new organisation when it was formed, and tried to use it to smear Labour and Independent Labour Party politicians as enemies of the working class. As the 1931 political crisis unfolded, the New Party became increasingly an irrelevance at the side of the much more tangible threat of the National government, although communists did campaign against Mosley in late 1931. Ultimately, the New Party was significant for the communists because it seemed to offer some vindication of the 'class against class' line; because it suggested that the CPGB was not always wrong in its analysis; because it led to increased attention to the party's youth movement; and because it led to the leading left-wing polemicist of the 1930s, John Strachey, working with the CPGB for almost a decade

Genetic determinants of cortical structure (thickness, surface area and volumes) among disease free adults in the CHARGE Consortium

Cortical thickness, surface area and volumes (MRI cortical measures) vary with age and cognitive function, and in neurological and psychiatric diseases. We examined heritability, genetic correlations and genome-wide associations of cortical measures across the whole cortex, and in 34 anatomically predefined regions. Our discovery sample comprised 22,824 individuals from 20 cohorts within the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium and the United Kingdom Biobank. Significant associations were replicated in the Enhancing Neuroimaging Genetics through Meta-analysis (ENIGMA) consortium, and their biological implications explored using bioinformatic annotation and pathway analyses. We identified genetic heterogeneity between cortical measures and brain regions, and 160 genome-wide significant associations pointing to wnt/β-catenin, TGF-β and sonic hedgehog pathways. There was enrichment for genes involved in anthropometric traits, hindbrain development, vascular and neurodegenerative disease and psychiatric conditions. These data are a rich resource for studies of the biological mechanisms behind cortical development and aging

Firn data compilation reveals widespread decrease of firn air content in western Greenland

The perennial snow, or firn, on the Greenland ice sheet each summer stores part of the meltwater formed at the surface, buffering the ice sheet’s contribution to sea level. We gathered observations of firn air content, indicative of the space available in the firn to retain meltwater, and find that this air content remained stable in cold regions of the firn over the last 65 years but recently decreased significantly in western Greenland