Turbulent mixing and the formation of an intermediate nepheloid layer above the Siberian continental shelf break

Intermediate nepheloid layers (INLs) form important pathways for the cross-slope transport and vertical export of particulate matter, including carbon. While intermediate maxima in particle settling fluxes have been reported in the Eurasian Basin of the Arctic Ocean, direct observations of turbid INLs above the continental slope are still lacking. In this study, we provide the first direct evidence of an INL, coinciding with enhanced mid-water turbulent dissipation rates, over the Laptev Sea continental slope in summer 2018. Current velocity data show a period of enhanced downslope flow with depressed isopcynals, suggesting that the enhanced turbulent dissipation is probably the consequence of the presence of an unsteady lee wave. Similar events occur mostly during ice free periods, suggesting an increasing frequency of episodic cross-slope particle transport in the future. The discovery of the INL and the episodic generation mechanism provide new insights into particle transport dynamics in this rapidly changing environment

Intensification of Near-Surface Currents and Shear in the Eastern Arctic Ocean:A More Dynamic Eastern Arctic Ocean

A 15-year (2004–2018) record of mooring observations from the upper 50 m of the ocean in the eastern Eurasian Basin reveals increased current speeds and vertical shear, associated with an increasing coupling between wind, ice, and the upper ocean over 2004–2018, particularly in summer. Substantial increases in current speeds and shears in the upper 50 m are dominated by a two times amplification of currents in the semidiurnal band, which includes tides and wind-forced near-inertial oscillations. For the first time the strengthened upper ocean currents and shear are observed to coincide with weakening stratification. This coupling links the Atlantic Water heat to the sea ice, a consequence of which would be reducing regional sea ice volume. These results point to a new positive feedback mechanism in which reduced sea ice extent facilitates more energetic inertial oscillations and associated upper-ocean shear, thus leading to enhanced ventilation of the Atlantic Water

On the Along-Slope Heat Loss of the Boundary Current in the Eastern Arctic Ocean

This study presents recent observations to quantify oceanic heat fluxes along the continental slope of the Eurasian part of the Arctic Ocean, in order to understand the dominant processes leading to the observed along-track heat loss of the Arctic Boundary Current (ABC). We investigate the fate of warm Atlantic Water (AW) along the Arctic Ocean continental margin of the Siberian Seas based on 11 cross-slope conductivity, temperature, depth transects and direct heat flux estimates from microstructure profiles obtained in summer 2018. The ABC loses on average urn:x-wiley:21699275:media:jgrc24332:jgrc24332-math-0006(108) J m−2 per 100 km during its propagation along the Siberian shelves, corresponding to an average heat flux of 47 W m−2 out of the AW layer. The measured vertical heat flux on the upper AW interface of on average 10 W m−2 in the deep basin, and 3.7 W m−2 above the continental slope is larger than previously reported values. Still, these heat fluxes explain less than 20% of the observed heat loss within the boundary current. Heat fluxes are significantly increased in the turbulent near-bottom layer, where AW intersects the continental slope, and at the lee side of a topographic irregularity. This indicates that mixing with ambient colder water along the continental margins is an important contribution to AW heat loss. Furthermore, the cold halocline layer receives approximately the same amount of heat due to upward mixing from the AW, compared to heat input from the summer-warmed surface layer above. This underlines the importance of both surface warming and increased vertical mixing in a future ice-free Arctic Ocean in summer

Observed interannual changes beneath Filchner-Ronne Ice Shelf linked to large-scale atmospheric circulation

Floating ice shelves are the Achilles’ heel of the Antarctic Ice Sheet. They limit Antarctica’s contribution to global sea level rise, yet they can be rapidly melted from beneath by a warming ocean. At Filchner-Ronne Ice Shelf, a decline in sea ice formation may increase basal melt rates and accelerate marine ice sheet mass loss within this century. However, the understanding of this tipping-point behavior largely relies on numerical models. Our new multi-annual observations from five hot-water drilled boreholes through Filchner-Ronne Ice Shelf show that since 2015 there has been an intensification of the density-driven ice shelf cavity-wide circulation in response to reinforced wind-driven sea ice formation in the Ronne polynya. Enhanced southerly winds over Ronne Ice Shelf coincide with westward displacements of the Amundsen Sea Low position, connecting the cavity circulation with changes in large-scale atmospheric circulation patterns as a new aspect of the atmosphere-ocean-ice shelf system

Shared genetic risk between eating disorder- and substance-use-related phenotypes: Evidence from genome-wide association studies

Eating disorders and substance use disorders frequently co-occur. Twin studies reveal shared genetic variance between liabilities to eating disorders and substance use, with the strongest associations between symptoms of bulimia nervosa and problem alcohol use (genetic correlation [rg], twin-based = 0.23-0.53). We estimated the genetic correlation between eating disorder and substance use and disorder phenotypes using data from genome-wide association studies (GWAS). Four eating disorder phenotypes (anorexia nervosa [AN], AN with binge eating, AN without binge eating, and a bulimia nervosa factor score), and eight substance-use-related phenotypes (drinks per week, alcohol use disorder [AUD], smoking initiation, current smoking, cigarettes per day, nicotine dependence, cannabis initiation, and cannabis use disorder) from eight studies were included. Significant genetic correlations were adjusted for variants associated with major depressive disorder and schizophrenia. Total study sample sizes per phenotype ranged from ~2400 to ~537 000 individuals. We used linkage disequilibrium score regression to calculate single nucleotide polymorphism-based genetic correlations between eating disorder- and substance-use-related phenotypes. Significant positive genetic associations emerged between AUD and AN (rg = 0.18; false discovery rate q = 0.0006), cannabis initiation and AN (rg = 0.23; q < 0.0001), and cannabis initiation and AN with binge eating (rg = 0.27; q = 0.0016). Conversely, significant negative genetic correlations were observed between three nondiagnostic smoking phenotypes (smoking initiation, current smoking, and cigarettes per day) and AN without binge eating (rgs = −0.19 to −0.23; qs < 0.04). The genetic correlation between AUD and AN was no longer significant after co-varying for major depressive disorder loci. The patterns of association between eating disorder- and substance-use-related phenotypes highlights the potentially complex and substance-specific relationships among these behaviors. © 2020 Society for the Study of Addictio

Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa

Characterized primarily by a low body-mass index, anorexia nervosa is a complex and serious illness1, affecting 0.9–4% of women and 0.3% of men2–4, with twin-based heritability estimates of 50–60%5. Mortality rates are higher than those in other psychiatric disorders6, and outcomes are unacceptably poor7. Here we combine data from the Anorexia Nervosa Genetics Initiative (ANGI)8,9 and the Eating Disorders Working Group of the Psychiatric Genomics Consortium (PGC-ED) and conduct a genome-wide association study of 16,992 cases of anorexia nervosa and 55,525 controls, identifying eight significant loci. The genetic architecture of anorexia nervosa mirrors its clinical presentation, showing significant genetic correlations with psychiatric disorders, physical activity, and metabolic (including glycemic), lipid and anthropometric traits, independent of the effects of common variants associated with body-mass index. These results further encourage a reconceptualization of anorexia nervosa as a metabo-psychiatric disorder. Elucidating the metabolic component is a critical direction for future research, and paying attention to both psychiatric and metabolic components may be key to improving outcomes. © 2019, The Author(s), under exclusive licence to Springer Nature America, Inc

Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa.

Characterized primarily by a low body-mass index, anorexia nervosa is a complex and serious illness <sup>1</sup> , affecting 0.9-4% of women and 0.3% of men <sup>2-4</sup> , with twin-based heritability estimates of 50-60% <sup>5</sup> . Mortality rates are higher than those in other psychiatric disorders <sup>6</sup> , and outcomes are unacceptably poor <sup>7</sup> . Here we combine data from the Anorexia Nervosa Genetics Initiative (ANGI) <sup>8,9</sup> and the Eating Disorders Working Group of the Psychiatric Genomics Consortium (PGC-ED) and conduct a genome-wide association study of 16,992 cases of anorexia nervosa and 55,525 controls, identifying eight significant loci. The genetic architecture of anorexia nervosa mirrors its clinical presentation, showing significant genetic correlations with psychiatric disorders, physical activity, and metabolic (including glycemic), lipid and anthropometric traits, independent of the effects of common variants associated with body-mass index. These results further encourage a reconceptualization of anorexia nervosa as a metabo-psychiatric disorder. Elucidating the metabolic component is a critical direction for future research, and paying attention to both psychiatric and metabolic components may be key to improving outcomes

Genetic identification of cell types underlying brain complex traits yields insights into the etiology of Parkinson’s disease

Genome-wide association studies have discovered hundreds of loci associated with complex brain disorders, but it remains unclear in which cell types these loci are active. Here we integrate genome-wide association study results with single-cell transcriptomic data from the entire mouse nervous system to systematically identify cell types underlying brain complex traits. We show that psychiatric disorders are predominantly associated with projecting excitatory and inhibitory neurons. Neurological diseases were associated with different cell types, which is consistent with other lines of evidence. Notably, Parkinson’s disease was genetically associated not only with cholinergic and monoaminergic neurons (which include dopaminergic neurons) but also with enteric neurons and oligodendrocytes. Using post-mortem brain transcriptomic data, we confirmed alterations in these cells, even at the earliest stages of disease progression. Our study provides an important framework for understanding the cellular basis of complex brain maladies, and reveals an unexpected role of oligodendrocytes in Parkinson’s disease. © 2020, The Author(s), under exclusive licence to Springer Nature America, Inc