Source apportionment of methane escaping the subsea permafrost system in the outer Eurasian Arctic Shelf
The East Siberian Arctic Shelf holds large amounts of inundated carbon and methane (CH4). Holocene warming by overlying seawater, recently fortified by anthropogenic warming, has caused thawing of the underlying subsea permafrost. Despite extensive observations of elevated seawater CH4 in the past decades, relative contributions from different subsea compartments such as early diagenesis, subsea permafrost, methane hydrates, and underlying thermogenic/ free gas to these methane releases remain elusive. Dissolved methane concentrations observed in the Laptev Sea ranged from 3 to 1,500 nM (median 151 nM; oversaturation by ∼3,800%). Methane stable isotopic composition showed strong vertical and horizontal gradients with source signatures for two seepage areas of δ13C-CH4 = (−42.6 ± 0.5)/(−55.0 ± 0.5) ‰ and δD-CH4 = (−136.8 ± 8.0)/(−158.1 ± 5.5) ‰, suggesting a thermogenic/natural gas source. Increasingly enriched δ13C-CH4 and δD-CH4 at distance from the seeps indicated methane oxidation. The Δ14C-CH4 signal was strongly depleted (i.e., old) near the seeps (−993 ± 19/−1050 ± 89‰). Hence, all three isotope systems are consistent with methane release from an old, deep, and likely thermogenic pool to the outer Laptev Sea. This knowledge of what subsea sources are contributing to the observed methane release is a prerequisite to predictions on how these emissions will increase over coming decades and centuries.
Throughout the twentieth century, glaciologists and geophysicists from Denmark, Norway andSweden made important scientific contributions across the Arctic and Antarctic. This research was of acute security and policy interest during the Cold War, as knowledge of the polar regions assumed military importance. But scientists also helped make the polar regionsNordic spaces in a cultural and political sense, with scientists from Norden punching far above their weight in terms of population, geographical size or economic activity. This volume presents an image of Norden that stretches far beyond its conventional limits,covering a vast area in the North Atlantic and the Arctic Sea, as well as parts of Antarctica. Rich in resources, scarce in population, but critically important in global and regional geopolitics, these spaces were contested by major powers such as Russia, the United States, Canada and, in the Antarctic, Argentina, Australia, South Africa and others. The empirical focus on Danish, Norwegian and Swedish influence in the polar regions during the twentieth century embraces a diverse array of themes, from the role of science in policy and diplomacy to the tensions between nationalism and internationalism, with clear relevance to the important role science plays in contemporary discussions about Nordic engagement with the polar regions.
The first volume involves the Russian Federation as a common denominator with either Norway (oldest multilateral region in the Arctic) or the United States (sharing with Russia the longest maritime boundary in the world) to interpret changes with connected biophysical and socio-economic systems that underscore decisions across a “continuum of urgencies” from security to sustainability time scales. The second and third volumes will emerge from presentations during the annual Arctic Frontiers Conferences in Tromsø, Norway, starting in January 2020. Volume 2 will consider circumstances associated with areas beyond sovereign jurisdictions from Arctic and non-Arctic perspectives, recognizing the international community has unambiguous rights and responsibilities in the Arctic High Seas under the law of the sea. Volume 3 is intended to synthesize insights on a pan-Arctic scale, analogous to the world ocean across all sea zones, involving decisions to achieve ongoing progress with sustainability, coupling governance mechanisms and built infrastructure. Throughout this book series, which we expect to expand beyond the Arctic, science diplomacy will be applied as an international, interdisciplinary, and inclusive (holistic) process, facilitating informed decisionmaking to balance national interests and common interests for the benefit of all on Earth across generations. With holistic integration, this book series will reveal skills, methods, and theory of informed decisionmaking that will continue to evolve, contributing to balance, resilience, and stability that underlie progress with sustainability across our home planet.
The EU-Russia common space on external security is examined.
This chapter is a first attempt to study the development of different kind of field stations in the western sector of the Russian Arctic in theperiod from the First to Second International Polar Years (1882 - 1933). As more or less independent entities, marine biological and polar meteorological stations were on different sides of the process but were interconnected through the people involved and the filed research practices implemented.Three major concerns influenced the development of field studies in the Russian Arctic – navigation, demands for the efficient use of natural resources and the political–military strategy of keeping land and their surrounding seas under Soviet control. Stations gradually moved further north from the sub-Arctic to the Arctic islands.The scientific network in the Arctic was initially established through the confrontation between interrelated sites of knowledge – field stations and research vessels – before their merger and placement in the same centralized network, which subsequently became very efficient with the introduction of aviation. The stations were not just crucial places for knowledge production but also places for the transfer of scientific, primarily tacit, knowledge about observations and laboratory analysis. They also maintained a specific culture of field sciences. By the time of the Second IPY in the Soviet Arctic, a distinct shift could be seen from broad international cooperation to a centralized national network and from scientific, educational and local economic objectives to military, geopolitical and broader economic interests.
Russian policies in the Arctic region is examined.
The post-Cold War Arctic has seen a transformation from military tension and a focus on national security to a concern for environmental and human security. As a result of this, the globalized Arctic has a high level of peace and stability, maintained by international cooperation between the Arctic states, northern indigenous peoples, sub-national governments and local actors. There has also been a shift from environmental protection to economic activities and, consequently, states easily trump other interests. Now, in the Arctic, these challenges require fresh thinking on a local and global scale. Regional wars, the 'war on terror', and economic crises have posed new threats to Northern security order.
In this chapter we want to see what historical narratives can tell us in order to better understand our concerns with the vanishing ice as evidence of a current mega-transition. Was the 2007 minimum unique? When and why did science start to study Arctic sea ice? Have there been periods of an ice-free Arctic Sea in the past? And, if they did occur, how does it impact on interpretations of our present- time discourse on the possible emergence of anice- free Arctic Sea? Climate change may, in retrospect, have appeared an obvious companion idea, but this relationship between ice and climate was rarely put forward as a serious alternative for the immediate future on the human timescale of decades, generations, or even centuries. But when it finally was, comparatively late in the middle of the twentieth century, sea ice was part of the story. We start by visiting the idea of an ice-free Arctic in the past, then moving on to the scientific undertakings on sea -ice in the Soviet Union. Interwar efforts outside the Soviet Union were as only matched by Nordic researchers, with whom we deal with subsequently. Finally we discuss the Cold -War effortsand their military connections. That science is interest-driven is evident throughout the entire period. Sea- ice minima may comprise straightforward facts, but the underlying knowledge is the outcome of a complex science politics of circumpolar ice.
One of the key advances in genome assembly that has led to a significant improvement in contig lengths has been improved algorithms for utilization of paired reads (mate-pairs). While in most assemblers, mate-pair information is used in a post-processing step, the recently proposed Paired de Bruijn Graph (PDBG) approach incorporates the mate-pair information directly in the assembly graph structure. However, the PDBG approach faces difficulties when the variation in the insert sizes is high. To address this problem, we first transform mate-pairs into edge-pair histograms that allow one to better estimate the distance between edges in the assembly graph that represent regions linked by multiple mate-pairs. Further, we combine the ideas of mate-pair transformation and PDBGs to construct new data structures for genome assembly: pathsets and pathset graphs.
Papers about natural protection territories
Many environmental stimuli present a quasi-rhythmic structure at different timescales that the brain needs to decompose and integrate. Cortical oscillations have been proposed as instruments of sensory de-multiplexing, i.e., the parallel processing of different frequency streams in sensory signals. Yet their causal role in such a process has never been demonstrated. Here, we used a neural microcircuit model to address whether coupled theta–gamma oscillations, as observed in human auditory cortex, could underpin the multiscale sensory analysis of speech. We show that, in continuous speech, theta oscillations can flexibly track the syllabic rhythm and temporally organize the phoneme-level response of gamma neurons into a code that enables syllable identification. The tracking of slow speech fluctuations by theta oscillations, and its coupling to gamma-spiking activity both appeared as critical features for accurate speech encoding. These results demonstrate that cortical oscillations can be a key instrument of speech de-multiplexing, parsing, and encoding.
Neuronal nicotinic acetylcholine receptors (NNRs) of the α7 subtype have been shown to contribute to the release of dopamine in the nucleus accumbens. The site of action and the underlying mechanism, however, are unclear. Here we applied a circuit modeling approach, supported by electrochemical in vivo recordings, to clarify this issue. Modeling revealed two potential mechanisms for the drop in accumbal dopamine efflux evoked by the selective α7 partial agonist TC-7020. TC-7020 could desensitize α7 NNRs located predominantly on dopamine neurons or glutamatergic afferents to them or, alternatively, activate α7 NNRs located on the glutamatergic afferents to GABAergic interneurons in the ventral tegmental area. Only the model based on desensitization, however, was able to explain the neutralizing effect of coapplied PNU-120596, a positive allosteric modulator. According to our results, the most likely sites of action are the preterminal α7 NNRs controlling glutamate release from cortical afferents to the nucleus accumbens. These findings offer a rationale for the further investigation of α7 NNR agonists as therapy for diseases associated with enhanced mesolimbic dopaminergic tone, such as schizophrenia and addiction