The build-up, configuration, and dynamical sensitivity of the Eurasian ice-sheet complex to Late Weichselian climatic and oceanic forcing

The Eurasian ice-sheet complex (EISC) was the third largest ice mass during the Last Glacial Maximum (LGM), after the Antarctic and North American ice sheets. Despite its global significance, a comprehensive account of its evolution from independent nucleation centres to its maximum extent is conspicuously lacking. Here, a first-order, thermomechanical model, robustly constrained by empirical evidence, is used to investigate the dynamics of the EISC throughout its build-up to its maximum configuration. The ice flow model is coupled to a reference climate and applied at 10 km spatial resolution across a domain that includes the three main spreading centres of the Celtic, Fennoscandian and Barents Sea ice sheets. The model is forced with the NGRIP palaeo-isotope curve from 37 ka BP onwards and model skill is assessed against collated flowsets, marginal moraines, exposure ages and relative sea-level history. The evolution of the EISC to its LGM configuration was complex and asynchronous; the western, maritime margins of the Fennoscandian and Celtic ice sheets responded rapidly and advanced across their continental shelves by 29 ka BP, yet the maximum aerial extent (5.48 × 106 km2) and volume (7.18 × 106 km3) of the ice complex was attained some 6 ka later at c. 22.7 ka BP. This maximum stand was short-lived as the North Sea and Atlantic margins were already in retreat whilst eastern margins were still advancing up until c. 20 ka BP. High rates of basal erosion are modelled beneath ice streams and outlet glaciers draining the Celtic and Fennoscandian ice sheets with extensive preservation elsewhere due to frozen subglacial conditions, including much of the Barents and Kara seas. Here, and elsewhere across the Norwegian shelf and North Sea, high pressure subglacial conditions would have promoted localised gas hydrate formation

Morphological evidence for marine ice stream shutdown, central Barents Sea

The authors would like to thank NERC Oil and Gas CDT for the funding and support. We would also like to thank MAREANO (www.mareano.no) and EMODnet Bathymetry Consortium 2016 (http://www.emodnet-bathymetry.eu) for providing bathymetric data. We would like to thank Sarah Greenwood and two anonymous reviewers whose comments helped us to improve the manuscript.Peer reviewedPublisher PD

Molecular portrait of cisplatin induced response in human testis cancer cell lines based on gene expression profiles

<p>Abstract</p> <p>Background</p> <p>Testicular germ cell tumors (TGCTs) respond well to cisplatin-based chemotherapy and show a low incidence of acquired resistance compared to most somatic tumors. The reasons for these specific characteristics are not known in detail but seem to be multifactorial. We have studied gene expression profiles of testicular and colon cancer derived cell lines treated with cisplatin. The main goal of this study was to identify novel gene expression profiles with their functional categories and the biochemical pathways that are associated with TGCT cells' response to cisplatin.</p> <p>Results</p> <p>Genes that were differentially expressed between the TGCT cell lines vs the (somatic) HCT116 cell line, after cisplatin treatment, were identified using the significance analysis of microarrays (SAM) method. The response of TGCT cells was strikingly different from that of HCT116, and we identified 1794 genes that were differentially expressed. Functional classification of these genes showed that they participate in a variety of different and widely distributed functional categories and biochemical pathways. Database mining showed significant association of genes (n = 41) induced by cisplatin in our study, and genes previously reported to by expressed in differentiated TGCT cells. We identified 37 p53-responsive genes that were altered after cisplatin exposure. We also identified 40 target genes for two microRNAs, hsa-mir-372 and 373 that may interfere with p53 signaling in TGCTs. The tumor suppressor genes <it>NEO1 </it>and <it>LATS2</it>, and the estrogen receptor gene <it>ESR1</it>, all have binding sites for p53 and hsa-mir-372/373. <it>NEO1 </it>and <it>LATS2 </it>were down-regulated in TGCT cells following cisplatin exposure, while <it>ESR1 </it>was up-regulated in TGCT cells. Cisplatin-induced genes associated with terminal growth arrest through senescence were identified, indicating associations which were not previously described for TGCT cells.</p> <p>Conclusion</p> <p>By linking our gene expression data to publicly available databases and literature, we provide a global pattern of cisplatin induced cellular response that is specific for testicular cancer cell lines. We have identified cisplatin-responsive functional classes and pathways, such as the angiogenesis, Wnt, integrin, and cadherin signaling pathways. The identification of differentially expressed genes in this study may contribute to a better understanding of the unusual sensitivity of TGCT to some DNA-damaging agents.</p

Serological screening for tick-borne encephalitis virus in eight Norwegian herds of semi-domesticated reindeer

Tick-borne encephalitis virus (TBEV) is found in Ixodes ricinus ticks throughout the area where viable tick populations exist. In Norway, TBEV is found in I. ricinus from the south coast until Brønnøy municipality in Nordland County and the range of the vector is expanding due to changes in climate, vegetation, host animals and environmental conditions. TBEV might thus have the potential to establish in new areas when I. ricinus expand its geographical distribution. At present, there is little knowledge on the status of the virus in high-altitude areas of inland regions in Norway. It has previously been indicated that reindeer may be an important sentinel species and indicator of the spread of ticks and TBEV in high-altitude regions. In this study, 408 semi-domesticated Eurasian tundra reindeer (Rangifer tarandus tarandus) from eight herds, from Tana in Troms and Finnmark County in northern Norway to Filefjell in Innlandet and Viken Counties in southern Norway, were screened for TBEV antibodies using a commercial enzyme-linked immunosorbent assay (ELISA). We found 16 TBEV reactive reindeer samples by ELISA; however, these results could not be confirmed by the serum neutralization test (SNT). This could indicate that a flavivirusand not necessarily TBEV, may be circulating among Norwegian semi-domesticated reindeer. The results also indicate that TBEV was not enzootic in Norwegian semi-domesticated reindeer in 2013–2015. This knowledge is important as an information base for future TBEV and flavivirus surveillance in Norway

The role of ocean and atmospheric dynamics in the marine-based collapse of the last Eurasian Ice Sheet

Information from former ice sheets may provide important context for understanding the response of today’s ice sheets to forcing mechanisms. Here we present a reconstruction of the last deglaciation of marine sectors of the Eurasian Ice Sheet, emphasising how the retreat of the Norwegian Channel and the Barents Sea ice streams led to separation of the British-Irish and Fennoscandian ice sheets at c. 18.700 and of the Kara-Barents Sea-Svalbard and Fennoscandian ice sheets between 16.000 and 15.000 years ago. Combined with ice sheet modelling and palaeoceanographic data, our reconstruction shows that the deglaciation, from a peak volume of 20 m of sea-level rise equivalent, was mainly driven by temperature forced surface mass balance in the south, and by Nordic Seas oceanic conditions in the north. Our results highlight the nonlinearity in the response of an ice sheet to forcing and the significance of ocean-ice-atmosphere dynamics in assessing the fate of contemporary ice sheets

The Postglacial response of Arctic Ocean gas hydrates to climatic amelioration

Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been argued that a gas hydrate gun could trigger abrupt climate change, the processes and rates of subsurface/atmospheric natural gas exchange remain uncertain. Here we investigate the dynamics between gas hydrate stability and environmental changes from the height of the last glaciation through to the present day. Using geophysical observations from offshore Svalbard to constrain a coupled ice sheet/gas hydrate model, we identify distinct phases of subglacial methane sequestration and subsequent release on ice sheet retreat that led to the formation of a suite of seafloor domes. Reconstructing the evolution of this dome field, we find that incursions of warm Atlantic bottom water forced rapid gas hydrate dissociation and enhanced methane emissions during the penultimate Heinrich event, the B?lling and Aller?d interstadials, and the Holocene optimum. Our results highlight the complex interplay between the cryosphere, geosphere, and atmosphere over the last 30,000 y that led to extensive changes in subseafloor carbon storage that forced distinct episodes of methane release due to natural climate variability well before recent anthropogenic warmingauthorsversionPeer reviewe

Distinct modes of meltwater drainage and landform development beneath the last Barents Sea ice sheet

The flow of glacial ice is impacted by basal meltwater drainage systems that fluctuate on a continuum from distributed, high-pressure environments to channelized, lower pressure networks. Understanding the long-term development of dominant drainage modes and impacts on ice flow and landform development is a crucial step in predicting palaeo and contemporary ice-mass response to changes in climate. The spatial and temporal scales at which different drainage modes operate are largely unknown, and the geomorphological legacy of subglacial meltwater networks that evolve over a glaciation provide composite records of drainage system development. Here, we use high-resolution bathymetric data from shallow banks in the central Barents Sea to map the geomorphological imprint of meltwater drainage beneath the collapsing marine-based Barents Sea Ice Sheet (BSIS). We observe a succession of distinct meltwater landforms that provide relative timing constraints for subglacial drainage modes, indicating that extensive networks of channelized drainage were in operation during deglaciation. Interlinked basins and channels suggest that meltwater availability and drainage system development was influenced by filling and draining cycles in subglacial lakes. Networks of eskers also indicate near-margin meltwater conduits incised into basal ice during late-stage deglaciation, and we suggest that these systems were supplemented by increased inputs from supraglacial melting. The abundance of meltwater during the late stages of BSIS deglaciation likely contributed to elevated erosion of the sedimentary substrate and the mobilisation of subglacial sediments, providing a sediment source for the relatively abundant eskers found deposited across bank areas. A newly discovered beaded esker system over 67 km long in Hopendjupet constrains a fluctuating, but generally decelerating, pace of ice retreat from ∼1,600 m a−1 to ∼620 m a−1 over central Barents Sea bank areas during a 91-year timespan

Legitimacy, communication and leadership in the Turnaround game

We study the effectiveness of leaders for inducing coordinated organizational change to a more efficient equilibrium, i.e., a turnaround. We compare communication from leaders to incentive increases and also compare the effectiveness of randomly selected and elected leaders. While all interventions yield shifts to more efficient equilibria, communication from leaders has a greater effect than incentives. Moreover, leaders who are elected by followers are significantly better at improving their group's outcome than randomly selected ones. The improved effectiveness of elected leaders results from sending more performance-relevant messages. Our results are evidence that the way in which leaders are selected affects their legitimacy and the degree to which they influence followers. Finally, we observed that a combination of factors- incentive increases and elected leaders-yield near universal turnarounds to full efficiency

Health care quality from the patients' perspective: a comparative study between an old and a new, high-tech hospital

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