Glacial history of Sør Rondane Mountains in Dronning Maud Land, East Antarctica introduced by geomorphology and surface exposure ages

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月26日（月）、27日（火） ２階ラウン

Ice Retreat History in Pine Island Bay, Revealed by Sedimentary Be-10 Records

Reconstruction of the past dynamics of the Antarctic ice sheets by studying records from their margin is essential to evaluate their stability and their contribution to future sea level rise. Recently, the first direct evidence for a paleo-subglacial lake on the Antarctic continental shelf was reported from a sediment core from a small bedrock basin in Pine Island Bay (PIB), West Antarctica. Here we report further evidence for this paleosubglacial lake based on down-core changes in Be-10 concentrations in the sediments. Very low Be-10 concentration in the lower part of the core indicate limited input of meteoric Be-10, suggesting deposition of the corresponding sediments in isolation from the open ocean. The Be-10 concentration shows a drop within a sand, silt and mud interval in the middle part of the core that was interpreted to result from deposition during the transition from the subglacial lake to a sub-ice shelf cavern caused by grounding line retreat in PIB around 11 kyrs B.P.. The Be-10 concentration increases significantly toward the top of the core, indicating the establishment of an open marine setting later during the Holocene. In addition, we report new Be-10 data from marine sediment cores in other parts of PIB. Our results demonstrate that Be-10 concentration changes in marine sediments from glaciated margins are a valuable recorder of ice sheet - ice shelf transitions

East Antarctic deglaciation and the link to global cooling during the Quaternary: evidence from glacial geomorphology and 10Be surface exposure dating of the Sør Rondane Mountains, Dronning Maud Land

AbstractReconstructing past variability of the Antarctic ice sheets is essential to understand their stability and to anticipate their contribution to sea level change as a result of future climate change. Recent studies have reported a significant decrease in thickness of the East Antarctic Ice Sheet (EAIS) during the last several million years. However, the geographical extent of this decrease and subsequent isostatic rebound remain uncertain. In this study, we reconstruct the magnitude and timing of ice sheet retreat at the Sør Rondane Mountains in Dronning Maud Land, East Antarctica, based on detailed geomorphological survey, cosmogenic exposure dating, and glacial isostatic adjustment modeling. Three distinct deglaciation phases are identified for this sector during the Quaternary, based on rock weathering and 10Be surface exposure data. We estimate that the ice sheet thinned by at least 500 m during the Pleistocene. This thinning is attributed to the reorganization of Southern Ocean circulation associated with global cooling into the Pleistocene, which reduced the transport of moisture from the Southern Ocean to the interior of EAIS. The data also show that since the Last Glacial Maximum the ice surface has lowered less than ca 50 m and that this lowering probably started after ca 14 ka. This suggests that the EAIS in Dronning Maud Land is unlikely to have been a major contributor to postglacial sea-level rise and Meltwater pulse 1A

Be-10 evidence for a paleo-subglacial lake and subsequent deglaciation processes in Pine Island Bay, West Antarctica

Reconstruction of the glacial dynamics of the Antarctic ice sheets during the past by studying records from their margin is essential to evaluate their stability and to anticipate their contribution to future sea level rise. Recently, the first direct evidence for a paleo-subglacial lake on the Antarctic continental shelf was reported from a small bedrock basin in Pine Island Bay, West Antarctica (Kuhn et al., 2017). The evidence is based on a distinct sediment facies and geochemical pore water signatures, i.e. low chloride concentrations, in a marine sediment core (PS69/288). These data indicate that the sediment in the lower part of the core was deposited under a low-energy subglacial lake setting. They also show that the location of the subglacial lake is consistent with the predicted distribution of subglacial lakes based on bathymetric data. Here we report further evidence for a paleo-subglacial lake based on changes in Be-10 concentrations in the sediments. A significant down-core decrease in the Be-10 concentration indicates very limited input of meteoric Be-10 to the sediments in the lower part of the core, suggesting a depositional environment that was isolated from the open ocean. This is consistent with the proposed subglacial lake setting. In detail, the Be-10 concentration shows a further drop within a sand, silt and mud interval from ca. 580 to 470 cm core depth that was interpreted to have been deposited during the transition from the subglacial lake to a sub-ice shelf cavern by grounding line retreat in that area at about 11 kyrs B.P. (Hillenbrand et al., 2013, Kuhn et al., 2017). The lowered Be-10 concentration at the base of this interval probably results from the dominant supply of sediment that had been deeply buried under the West Antarctic Ice Sheet (WAIS) for a very long time. Above a minor up-core increase from 464 to 324 cm, the Be-10 concentration decreases again at about 260 cm. This decrease may correspond to three possible factors: 1.) increased supply of sediments from below the ice sheet (possible meltwater plumes), 2.) an episode of permanent sea-ice cover, or 3.) a re-advance of the ice shelf. Above 260 cm the Be-10 concentration increases significantly toward the top of the core, indicating that an open marine setting had established at the core site. This data provides new insight into a more dynamic behaviour of the WAIS in Pine Island Bay during the Holocene. Overall, the Be-10 concentration of the sediments is a powerful tool to study paleo-subglacial lakes in Antarctica and processes of ice sheet to ice shelf transition during the subsequent deglaciation. Keywords: Subglacial Lake, Be-10, Ice sheet retreat, West Antarctica References Hillenbrand, C.-D., Kuhn, G., Smith, J.A., Gohl, K., Graham, A.G., Larter, R.D., Klages, J.P., Downey, R., Moreton, S.G., Forwick, M., Vaughan, D.G., 2013. Grounding-line retreat of the West Antarctic Ice Sheet from inner Pine Island Bay. Geology 41, 35–38. doi:10.1130/G33469.1. Past Antarctic Ice Sheet Dynamics (PAIS) Conference September 10-15th 2017, Trieste - Italy Kuhn, G., Hillenbrand, C.-D, Kasten, S., Smith, J.A., Nitsche, F.O., Frederichs, T., Wiers, S., Ehrmann, W., Klages, J.P., Mogollón, J.M. (in press). Evidence for a palaeo-subglacial lake on the Antarctic continental shelf. Nature Communications

Co-production of knowledge and sustainability transformations: a strategic compass for global research networks

An increasing number of voices highlight the need for science itself to transform and to engage in the co-production of knowledge and action, in order to enable the fundamental transformations needed to advance towards sustainable futures. But how can global sustainability-oriented research networks engage in co-production of knowledge and action? The present article introduces a strategic tool called the ‘network compass’ which highlights four generic, interrelated fields of action through which networks can strive to foster co-production. It is based on the networks’ particular functions and how these can be engaged for co-production processes. This tool aims to foster self-reflection and learning within and between networks in the process of (re)developing strategies and activity plans and effectively contributing to sustainability transformations

Pregnancy-related pelvic girdle pain: an update

A large number of scientists from a wide range of medical and surgical disciplines have reported on the existence and characteristics of the clinical syndrome of pelvic girdle pain during or after pregnancy. This syndrome refers to a musculoskeletal type of persistent pain localised at the anterior and/or posterior aspect of the pelvic ring. The pain may radiate across the hip joint and the thigh bones. The symptoms may begin either during the first trimester of pregnancy, at labour or even during the postpartum period. The physiological processes characterising this clinical entity remain obscure. In this review, the definition and epidemiology, as well as a proposed diagnostic algorithm and treatment options, are presented. Ongoing research is desirable to establish clear management strategies that are based on the pathophysiologic mechanisms responsible for the escalation of the syndrome's symptoms to a fraction of the population of pregnant women

Genome-wide associations for birth weight and correlations with adult disease

Birth weight (BW) is influenced by both foetal and maternal factors and in observational studies is reproducibly associated with future risk of adult metabolic diseases including type 2 diabetes (T2D) and cardiovascular disease1. These lifecourse associations have often been attributed to the impact of an adverse early life environment. We performed a multi-ancestry genome-wide association study (GWAS) meta-analysis of BW in 153,781 individuals, identifying 60 loci where foetal genotype was associated with BW (P <5x10-8). Overall, ˜15% of variance in BW could be captured by assays of foetal genetic variation. Using genetic association alone, we found strong inverse genetic correlations between BW and systolic blood pressure (rg-0.22, P =5.5x10-13), T2D (rg-0.27, P =1.1x10-6) and coronary artery disease (rg-0.30, P =6.5x10-9) and, in large cohort data sets, demonstrated that genetic factors were the major contributor to the negative covariance between BW and future cardiometabolic risk. Pathway analyses indicated that the protein products of genes within BW-associated regions were enriched for diverse processes including insulin signalling, glucose homeostasis, glycogen biosynthesis and chromatin remodelling. There was also enrichment of associations with BW in known imprinted regions (P =1.9x10-4). We have demonstrated that lifecourse associations between early growth phenotypes and adult cardiometabolic disease are in part the result of shared genetic effects and have highlighted some of the pathways through which these causal genetic effects are mediated

Genome-wide associations for birth weight and correlations with adult disease

Birth weight (BW) has been shown to be influenced by both fetal and maternal factors and in observational studies is reproducibly associated with future risk of adult metabolic diseases including type 2 diabetes (T2D) and cardiovascular disease. These life-course associations have often been attributed to the impact of an adverse early life environment. Here, we performed a multi-ancestry genome-wide association study (GWAS) meta-analysis of BW in 153,781 individuals, identifying 60 loci where fetal genotype was associated with BW ($\textit{P}$  < 5 × 10$^{-8}$). Overall, approximately 15% of variance in BW was captured by assays of fetal genetic variation. Using genetic association alone, we found strong inverse genetic correlations between BW and systolic blood pressure ($\textit{R}$ $_{g}$ = -0.22, $\textit{P}$  = 5.5 × 10$^{-13}$), T2D ($\textit{R}$ $_{g}$ = -0.27, $\textit{P}$  = 1.1 × 10$^{-6}$) and coronary artery disease ($\textit{R}$ $_{g}$ = -0.30, $\textit{P}$  = 6.5 × 10$^{-9}$). In addition, using large -cohort datasets, we demonstrated that genetic factors were the major contributor to the negative covariance between BW and future cardiometabolic risk. Pathway analyses indicated that the protein products of genes within BW-associated regions were enriched for diverse processes including insulin signalling, glucose homeostasis, glycogen biosynthesis and chromatin remodelling. There was also enrichment of associations with BW in known imprinted regions ($\textit{P}$ = 1.9 × 10$^{-4}$). We demonstrate that life-course associations between early growth phenotypes and adult cardiometabolic disease are in part the result of shared genetic effects and identify some of the pathways through which these causal genetic effects are mediated.For a full list of the funders pelase visit the publisher's website and look at the supplemetary material provided. Some of the funders are: British Heart Foundation, Cancer Research UK, Medical Research Council, National Institutes of Health, Royal Society and Wellcome Trust

Genome-wide analysis identifies 12 loci influencing human reproductive behavior.

The genetic architecture of human reproductive behavior-age at first birth (AFB) and number of children ever born (NEB)-has a strong relationship with fitness, human development, infertility and risk of neuropsychiatric disorders. However, very few genetic loci have been identified, and the underlying mechanisms of AFB and NEB are poorly understood. We report a large genome-wide association study of both sexes including 251,151 individuals for AFB and 343,072 individuals for NEB. We identified 12 independent loci that are significantly associated with AFB and/or NEB in a SNP-based genome-wide association study and 4 additional loci associated in a gene-based effort. These loci harbor genes that are likely to have a role, either directly or by affecting non-local gene expression, in human reproduction and infertility, thereby increasing understanding of these complex traits