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Author |
Steven Franke, Daniela Jansen, Sebastian Beyer, Niklas Neckel, Tobias Binder, John Paden, Olaf Eisen |
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Title |
Complex Basal Conditions and Their Influence on Ice Flow at the Onset of the Northeast Greenland Ice Stream |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Earth Surface |
Abbreviated Journal |
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Volume |
126 |
Issue  |
3 |
Pages |
e2020JF005689 |
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Keywords |
basal roughness bed conditions Greenland Ice Sheet ice stream Northeast Greenland Ice Stream radio-echo sounding |
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Abstract |
Abstract The ice stream geometry and large ice surface velocities at the onset region of the Northeast Greenland Ice Stream (NEGIS) are not yet well reproduced by ice sheet models. The quantification of basal sliding and a parametrization of basal conditions remains a major gap. In this study, we assess the basal conditions of the onset region of the NEGIS in a systematic analysis of airborne ultra-wideband radar data. We evaluate basal roughness and basal return echoes in the context of the current ice stream geometry and ice surface velocity. We observe a change from a smooth to a rougher bed where the ice stream widens, and a distinct roughness anisotropy, indicating a preferred orientation of subglacial structures. In the upstream region, the excess ice mass flux through the shear margins is evacuated by ice flow acceleration and along-flow stretching of the ice. At the downstream part, the generally rougher bed topography correlates with a decrease in flow acceleration and lateral variations in ice surface velocity. Together with basal water routing pathways, this hints to two different zones in this part of the NEGIS: the upstream region collecting water, with a reduced basal traction, and downstream, where the ice stream is slowing down and is widening on a rougher bed, with a distribution of basal water toward the shear margins. Our findings support the hypothesis that the NEGIS is strongly interconnected to the subglacial water system in its onset region, but also to the subglacial substrate and morphology. |
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1180 |
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2169-9003 |
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yes |
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7272 |
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Title |
Factors affecting adult body condition in the endangered northern rockhopper penguin |
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Year |
2021 |
Publication |
Marine Biology |
Abbreviated Journal |
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Volume |
168 |
Issue |
3 |
Pages |
27 |
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109,394 |
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Bachelor's thesis |
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ISSN |
1432-1793 |
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yes |
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Serial |
7792 |
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Author |
Alain Manceau, Anne-Claire Gaillot, Pieter Glatzel, Yves Cherel, Paco Bustamante |
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Journal |
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Year |
2021 |
Publication |
Environmental Science & Technology |
Abbreviated Journal |
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Volume |
55 |
Issue |
3 |
Pages |
1515-1526 |
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Abstract |
In vivo and in vitro evidence for detoxification of methylmercury (MeHg) as insoluble mercury selenide (HgSe) underlies the central paradigm that mercury exposure is not or little hazardous when tissue Se is in molar excess (Se:Hg > 1). However, this hypothesis overlooks the binding of Hg to selenoproteins, which lowers the amount of bioavailable Se that acts as a detoxification reservoir for MeHg, thereby underestimating the toxicity of mercury. This question was addressed by determining the chemical forms of Hg in various tissues of giant petrels Macronectes spp. using a combination of high energy-resolution X-ray absorption near edge structure and extended X-ray absorption fine structure spectroscopy, and transmission electron microscopy coupled to elemental mapping. Three main Hg species were identified, a MeHg-cysteinate complex, a four-coordinate selenocysteinate complex (Hg(Sec)4), and a HgSe precipitate, together with a minor dicysteinate complex Hg(Cys)2. The amount of HgSe decreases in the order liver > kidneys > brain = muscle, and the amount of Hg(Sec)4 in the order muscle > kidneys > brain > liver. On the basis of biochemical considerations and structural modeling, we hypothesize that Hg(Sec)4 is bound to the carboxy-terminus domain of selenoprotein P (SelP) which contains 12 Sec residues. Structural flexibility allows SelP to form multinuclear Hgx(Se,Sec)y complexes, which can be biomineralized to HgSe by protein self-assembly. Because Hg(Sec)4 has a Se:Hg molar ratio of 4:1, this species severely depletes the stock of bioavailable Se for selenoprotein synthesis and activity to one ?g Se/g dry wet in the muscle of several birds. This concentration is still relatively high because selenium is naturally abundant in seawater, therefore it probably does not fall below the metabolic need for essential selenium. However, this study shows that this may not be the case for terrestrial animals, and that muscle may be the first tissue potentially injured by Hg toxicity. |
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109 |
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ISSN |
0013-936X |
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yes |
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Call Number |
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Serial |
7942 |
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Title |
Per- and Polyfluoroalkyl Substances Are Positively Associated with Thyroid Hormones in an Arctic Seabird |
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Journal |
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Year |
2021 |
Publication |
Environmental Toxicology and Chemistry |
Abbreviated Journal |
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Volume |
40 |
Issue |
3 |
Pages |
820-831 |
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Keywords |
Avian toxicity Ecotoxicology Endocrine-disrupting compounds Per- and polyfluoroalkyl substance Thyroid hormones |
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Abstract |
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Programme |
330 |
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ISSN |
1552-8618 |
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yes |
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Serial |
7967 |
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Title |
Toward a global strategy for seabird tracking |
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Journal |
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Year |
2021 |
Publication |
Conservation Letters |
Abbreviated Journal |
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Volume |
14 |
Issue |
3 |
Pages |
e12804 |
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Keywords |
biogeography biologging biotelemetry ecological monitoring marine conservation oceanography spatial planning threatened species |
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Abstract |
Electronic tracking technologies revolutionized wildlife ecology, notably for studying the movements of elusive species such as seabirds. Those advances are key to seabird conservation, for example in guiding the design of marine protected areas for this highly threatened group. Tracking data are also boosting scientific understanding of marine ecosystem dynamics in the context of global change. To optimize future tracking efforts, we performed a global assessment of seabird tracking data. We identified and mined 689 seabird tracking studies, reporting on > 28,000 individuals of 216 species from 17 families over the last four decades. We found substantial knowledge gaps, reflecting a historical neglect of tropical seabird ecology, with biases toward species that are heavier, oceanic, and from high-latitude regions. Conservation status had little influence on seabird tracking propensity. We identified 54 threatened species for which we did not find published tracking records, and 19 with very little data. Additionally, much of the existing tracking data are not yet available to other researchers and decision-makers in online databases. We highlight priority species and regions for future tracking efforts. More broadly, we provide guidance toward an ethical, rational, and efficient global tracking program for seabirds, as a contribution to their conservation. |
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388 |
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ISSN |
1755-263X |
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yes |
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Serial |
7981 |
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Author |
Peter S. Ungar, Blaire Van Valkenburgh, Alexandria S. Peterson, Aleksandr A. Sokolov, Natalia A. Sokolova, Dorothee Ehrich, Ivan A. Fufachev, Olivier Gilg, Alexandra Terekhina, Alexander Volkovitskiy, Viktor Shtro |
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Title |
Dental evidence for variation in diet over time and space in the Arctic fox, Vulpes lagopus |
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Journal |
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Year |
2021 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
44 |
Issue |
3 |
Pages |
509-523 |
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Abstract |
Studies of the effects of variation in resource availability are important for understanding the ecology of high-latitude mammals. This paper examines the potential of dental evidence (tooth wear and breakage) as a proxy for diet and food choice in Vulpes lagopus, the Arctic fox. It presents a preliminary study of dental microwear, gross wear score, and tooth breakage in a sample (n?=?78 individuals) from the Yamal Peninsula of the Russian Arctic. While these measures have each been associated with feeding ecology in larger carnivorans (e.g., proportion of bone in the diet), they have yet to be combined in any study and have rarely been applied to smaller species or those from high latitudes. Arctic foxes from the north and south of the peninsula, and those from rodent peak and trough density periods, are compared to assess impact of changes in food availability across space and time. Results indicate that microwear textures vary in dispersion, with more variation in texture complexity, including higher values (suggesting more consumption of bone), in the rodent-poor period in the north of Yamal. Gross wear scores and tooth breakage are also significantly higher for the north of Yamal than the south. These data together suggest that dental evidence can provide important insights into variation in the feeding ecology of Arctic foxes and potentially into the impacts of changes in food abundance across space and time. |
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1036 |
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ISSN |
1432-2056 |
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yes |
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7982 |
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Title |
The story of endurance: Biogeography and the evolutionary history of four Holarctic butterflies with different habitat requirements |
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Journal |
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Year |
2021 |
Publication |
Journal of Biogeography |
Abbreviated Journal |
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Volume |
48 |
Issue |
3 |
Pages |
590-602 |
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Keywords |
COI Ef-1? insect Lepidoptera mammoth steppe Pleistocene Quaternary RpS5 species distribution modelling |
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Abstract |
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Programme |
1036 |
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ISSN |
1365-2699 |
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yes |
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7984 |
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Author |
L A Ermert, K Sager, T Nissen-Meyer, A Fichtner |
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Title |
Multifrequency inversion of global ambient seismic sources |
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Journal |
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Year |
2021 |
Publication |
Geophysical Journal International |
Abbreviated Journal |
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Volume |
225 |
Issue |
3 |
Pages |
1616-1623 |
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133 |
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ISSN |
0956-540X |
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yes |
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Serial |
7992 |
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Author |
Jun Xie, Risheng Chu, Sidao Ni |
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Title |
Evaluating Global Tomography Models With Antipodal Ambient Noise Cross-Correlation Functions |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Solid Earth |
Abbreviated Journal |
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Volume |
126 |
Issue |
3 |
Pages |
e2020JB020444 |
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Keywords |
ambient noise cross-correlation functions antipodal surface waves mantle heterogeneity tomography model evaluation |
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133 |
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ISSN |
2169-9356 |
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yes |
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7993 |
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Title |
Evolution of the Cook Ice Cap (Kerguelen Islands) between the last centuries and 2100 ce based on cosmogenic dating and glacio-climatic modelling |
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Journal |
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Year |
2021 |
Publication |
Antarctic Science |
Abbreviated Journal |
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Volume |
33 |
Issue |
3 |
Pages |
301-317 |
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Keywords |
degree-day glaciological model future projections glacial fluctuations in situ cosmogenic chlorine-36 dating moraines sub-Antarctic islands |
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Abstract |
The Cook Ice Cap (CIC) on the sub-Antarctic Kerguelen Islands recently experienced extremely negative surface mass balance. Further deglaciation could have important impacts on endemic and invasive fauna and flora. To put this exceptional glacier evolution into a multi-centennial-scale context, we refined the evolution of the CIC over the last millennium, investigated the associated climate conditions and explored its potential evolution by 2100 ce. A glaciological model, constrained by cosmic ray exposure dating of moraines, historical documents and recent direct mass balance observations, was used to simulate the ice-cap extents during different phases of advance and retreat between the last millennium and 2100 ce. Cosmogenic dating suggests glacial advance around the early Little Ice Age (LIA), consistent with findings from other sub-Antarctic studies, and the rather cold and humid conditions brought about by the negative phase of the Southern Annular Mode (SAM). This study contributes to our currently limited understanding of palaeoclimate for the early LIA in the southern Indian Ocean. Glaciological modelling and observations confirm the recent decrease in CIC extent linked to the intensification of the SAM. Although affected by large uncertainties, future simulations suggest a complete disappearance of CIC by the end of the century. |
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1048 |
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ISSN |
0954-1020, 1365-2079 |
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yes |
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8187 |
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