Water Body Distributions Across Scales: A Remote Sensing Based Comparison of Three Arctic Tundra Wetlands

Water bodies are ubiquitous features in Arctic wetlands. Ponds, i.e., waters with a surface area smaller than 104 m2, have been recognized as hotspots of biological activity and greenhouse gas emissions but are not well inventoried. This study aimed to identify common characteristics of three Arctic wetlands including water body size and abundance for different spatial resolutions, and the potential of Landsat-5 TM satellite data to show the subpixel fraction of water cover (SWC) via the surface albedo. Water bodies were mapped using optical and radar satellite data with resolutions of 4mor better, Landsat-5 TM at 30mand the MODIS water mask (MOD44W) at 250m resolution. Study sites showed similar properties regarding water body distributions and scaling issues. Abundance-size distributions showed a curved pattern on a log-log scale with a flattened lower tail and an upper tail that appeared Paretian. Ponds represented 95% of the total water body number. Total number of water bodies decreased with coarser spatial resolutions. However, clusters of small water bodies were merged into single larger water bodies leading to local overestimation of water surface area. To assess the uncertainty of coarse-scale products, both surface water fraction and the water body size distribution should therefore be considered. Using Landsat surface albedo to estimate SWC across different terrain types including polygonal terrain and drained thermokarst basins proved to be a robust approach. However, the albedo–SWC relationship is site specific and needs to be tested in other Arctic regions. These findings present a baseline to better represent small water bodies of Arctic wet tundra environments in regional as well as global ecosystem and climate models

SOX11 interactome analysis: Implication in transcriptional control and neurogenesis

Somatische Stammzellen können sich durch mitotische Teilung vermehren, was eine Regeneration vieler Gewebe nach Verletzungen oder Infektion ermöglicht. Im adulten Säugerhirn kann der Verlust von post-mitotischen Neuronen jedoch nicht kompensiert werden. Eine Ausnahme bildet die das gesamte erwachsene Leben andauernde Differenzierung von Neuronen aus einem Pool von neuronalen Stammzellen. Dieser Prozess, bezeichnet als adulte Neurogenese, ist auf einige spezielle Bereiche des Gehirns, die neurogenen Nischen beschränkt. Dessen Regulierung unterliegt einer komplexen Maschinerie aus extrinsischen und intrinsischen Mechanismen. Bei den intrazellulären Prozessen der adulten Neurogenese spielen die Proteine aus der Familie der SOX Transkriptionsfaktoren eine entscheidende Rolle. Das SOXC Protein SOX11 stellt einen essentiellen Faktor während der Festlegung des neuronalen Schicksals von Vorläuferzellen und der Initiierung von frühen neuronalen Expressionsprogrammen dar. Aktuelle Modelle deuten darauf hin, dass sowohl die Erhaltung der Stammzelleigenschaften als auch die Differenzierung von zentralen Transkriptionsnetzwerken reguliert werden. Diese bestehen aus interagierenden Transkriptionsfaktoren, welche zusammen Genexpressionsprogramme kontrollieren. Aufgrund dieser Erkenntnisse, wurde die Studie darauf ausgelegt, regulatorische Prozesse der späten neuronalen Differenzierung und Reifung zu identifizieren, welche die frühe neuronale Identität innerhalb der unreifen Neuronen definieren. Durch seine zentrale Bedeutung für die neuronale Differenzierung und die Initiierung der Expression neuronaler Marker, wurde SOX11 als Ausgangspunkt für die Analyse des zu Grunde liegenden Transkriptionsnetzwerks gewählt. SOX11-spezifische monoklonale Antikörper wurden zur Detektion des Proteins auf Western Blot Ebene generiert und validiert. Das SOX11-assoziierte Transkriptionsnetzwerk wurde durch die Bestimmung des SOX11-Interaktoms in Neuro2a Zellen mithilfe von Affinitätsaufreinigung und quantitativer Massenspektrometrie erstellt. Das identifizierte SOX11-spezifische Interaktom wies eine signifikante Anreicherung von Transkriptionsfaktoren und anderen Regulatoren auf Transkriptionsebene auf. Literaturrecherche und GO Term Analyse verifizierten darüber hinaus einige der Interaktoren als modulierende Proteine während der Neurogenese. Ein Protein-Protein Interaktionsnetzwerk, in dem die experimentell bestimmten Daten mit Informationen aus öffentlichen Interaktionsdatenbanken vervollständigt wurden, zeigt die Interaktionen zwischen den Proteinen, sowie die Konnektivität einzelner Faktoren. Ausgewählte SOX11 Interaktoren wurden mithilfe von Promotorstudien funktionell charakterisiert. Analysiert wurde der Einfluss auf die durch SOX11 aktivierten Promotoren von DCX und Stathmin1, zwei Markerproteine der frühen neuronalen Identität. Zwei Transkriptionsfaktoren, MYT1 und YY1, zeigten einen kooperativen Effekt mit SOX11 auf die Promotoren beider Gene. In silico Promotoranalysen für DCX und Stathmin1 ergaben benachbarte Bindungssequenzen sowohl für MYT1 und SOX11, als auch für YY1 und SOX11 innerhalb des DCX Promotors und für MYT1 und SOX11 innerhalb des Stathmin1 Promotors, durch welche die Kooperation der Transkriptionsfaktoren auf den Promotoren ermöglicht wird. Zudem ergab das Genom-weite Bindungsprofil von MYT1 und SOX11 eine Anreicherung von in die Neurogenese involvierten Genen. Die proteomische Analyse des SOX11-Transkriptionsnetzwerks in Kombination mit funktionellen Promotorstudien identifizierte neue Faktoren, die eine Rolle bei der intrinsischen Modulierung der späten Neurogenese spielen und deckte die kooperative Aktivität von MYT1 und YY1 mit SOX11 in Bezug auf die Regulierung früher neuronaler Markern auf. Zusätzlich wurden einige Kandidaten identifiziert, die möglicherweise Strategien zur Reprogrammierung von somatischen Zellen in funktionelle Neuronen verbessern können und damit einen Beitrag zur regenerativen Medizin leisten

Depolarized guided acoustic wave Brillouin scattering in hollow-core photonic crystal fibers

By performing quantum-noise-limited optical heterodyne detection, we observe polarization noise in light after propagation through a hollow-core photonic crystal fiber (PCF). We compare the noise spectrum to the one of a standard fiber and find an increase of noise even though the light is mainly transmitted in air in a hollow-core PCF. Combined with our simulation of the acoustic vibrational modes in the hollow-core PCF, we are offering an explanation for the polarization noise with a variation of guided acoustic wave Brillouin scattering (GAWBS). Here, instead of modulating the strain in the fiber core as in a solid core fiber, the acoustic vibrations in hollow-core PCF influence the effective refractive index by modulating the geometry of the photonic crystal structure. This induces polarization noise in the light guided by the photonic crystal structure.Comment: 8 pages, 5 figure

Assembly and concept of a web-based GIS within the paleolimnological project CONTINENT (Lake Baikal, Russia)

Web-based Geographical Information Systems (GIS) are excellent tools within interdisciplinary and multi-national geoscience projects to exchange and visualize project data. The web-based GIS presented in this paper was designed for the paleolimnological project 'High-resolution CONTINENTal paleoclimate record in Lake Baikal' (CONTINENT) (Lake Baikal, Siberia, Russia) to allow the interactive handling of spatial data. The GIS database combines project data (core positions, sample positions, thematic maps) with auxiliary spatial data sets that were downloaded from freely available data sources on the world wide web. The reliability of the external data was evaluated and suitable new spatial datasets were processed according to the scientific questions of the project. GIS analysis of the data was used to assist studies on sediment provenance in Lake Baikal, or to help answer questions such as whether the visualization of present-day vegetation distribution and pollen distribution supports the conclusions derived from palynological analyses. The refined geodata are returned back to the scientific community by using online data publication portals. Data were made citeable by assigning persistent identifiers (DOI) and were published through the German National Library for Science and Technology (TIB Hannover, Hannover, Germany).Continen

Trees on the tundra: warmer climate might not favor prostrate Larix tree but Betula nana shrub growth in Siberian tundra (Lena River Delta)

Tundra is primarily a habitat for shrub growth, not trees, but growth of prostrate forms of trees has been reported occasionally from the subarctic tundra region. In the light of on-going climate change, climate sensitivity studies of these unique trees are essential to predict vegetation dynamics and potential northward expansion of boreal forest tree species into tundra. Here we studied one of the northernmost Larix Mill. trees and Betula nana L. shrubs (72°N) from the Siberian tundra for the common period 1980-2017. We took advantage of the discovery of a single cohort of prostrate Larix trees within a tundra ecosystem, i.e., ca. 60 km northwards from the northern treeline, and compared climate-growth relationships of the two species. Both woody plants were sensitive to the July temperature, however this relationship was stable across the entire study period (1980-2017) only for Betula nana chronology. Additionally, radial growth of Larix trees became negatively correlated to temperatures during the previous summer. In recent period moisture sensitivity between Larix trees and Betula nana shrubs was contrasting, with generally wetter soil conditions favoring Larix trees growth and dryer conditions promoting Betula nana growth. Our study indicates that Larix trees radial growth in recent years is more sensitive to moisture than to summer air temperatures, whereas temperature sensitivity of Betula nana shrub is stable over time. We provide first detailed insight into the annual resolution on Larix tree growth sensitivity to climate in the heart of the tundra. The potentially higher Betula nana shrub resistance to warmer and drier climate versus Larix trees on a tundra revealed in our study needs to be further examined across habitats of various soil, moisture and permafrost status

Dissolved organic matter properties in arctic coastal waters are strongly influenced by fluxes from permafrost coasts and by local meteorology.

Under future climate change scenarios, Arctic coastal waters are believed to receive higher terrestrial organic matter (OM) fluxes. Permafrost carbon is increasingly mobilized upon thaw from rivers draining permafrost terrain and from eroding permafrost coasts. Once received, the coastal waters are the transformation zone for terrestrial OM, although quantities, especially those of dissolved organic matter (DOM) released by coastal erosion, are largely unknown. This nearshore zone plays a crucial role in Arctic biogeochemical cycling, as here the released material is destined to be (1) mineralized into greenhouse gases, (2) incorporated into marine primary production, (3) buried in nearshore sediments or (4) transported offshore. In this presentation, we show data on DOM quantities in surface water in the nearshore zone of the southern Beaufort Sea from two consecutive summer seasons under different meteorological conditions. Colored dissolved organic matter (cDOM) properties help to differentiate the terrestrial from the marine DOM component. Figure 1 shows DOC concentrations and salinities for 23 and 24 days in the summer seasons of 2013 and 2014, respectively. DOC concentrations in the nearshore zone of the southern Beaufort Sea vary between about 1.5 and 5 mg C L-1. In the Lena River Delta, bay water, river water, and permafrost meltwater creeks yielded similar values between 5.8 and 5.9 mg C L-1 (Dubinenkov et al., 2015). Similarly, Fritz et al. (2015) found DOC concentrations in ice wedges between 1.6 and 28.6 mg C L-1. In 2013, the first half of July was characterized by low salinity between 8 and 15 psu and high DOC concentrations of 3.5 to 5 mg C L-1. Then, a sudden change in water properties occurred after a major storm which lasted for at least 2 days. This storm led to strongly decreased DOC (1.5 to 2.5 mg C L-1) concentration and increasing salinity (14 to 28 psu) in surface water, probably due to upwelling In 2014, a more stable situation in both salinity and DOC prevailed, with relatively high salinity (23 to 29 psu) and low DOC concentration (1.5 to 2.5 mg C L-1). This pattern was due to rather windy and wavy conditions throughout the whole season. The water column in 2014 was likely well-mixed and DOC-poor because saline waters have probably been transported from the offshore to the nearshore. We recognized a significant negative correlation between DOC and salinity, independent from varying meteorological conditions. In general, this suggests a conservative mixing between DOC derived from terrestrial/permafrost runoff and marine DOC. The low salinity in July 2013 was probably due to prolonged sea-ice presence in the sampled area. This leads to the assumption that DOC also originates from melting sea ice. Quantitatively more important will be terrestrial runoff which is relatively rich in DOC. A stable stratification in the nearshore zone and calm weather conditions will increase the influence of terrestrial-derived DOM. The strength of the terrestrial influence can be estimated by salinity measures as they directly correlate with DOC concentrations; the lower the salinity the stronger the terrestrial influence. We conclude that the terrestrial imprint of coastal erosion on DOM concentrations in the nearshore zone is significant. We see that DOC concentrations are significantly elevated also compared to riverine input in front of river mouths and deltas. Meteorological conditions play a major role for the strength of the terrestrial DOM signal, which can vary on short timescales. Our approach is different from ship-based oceanography because we study DOM that is directly derived from thawing permafrost coasts, explicitly excluding rivers. When qualifying DOM origin from permafrost landscapes apart from rivers we have to take into consideration the different DOM mobilization pathways. 1) Surface runoff and near-surface groundwater flow mainly drain and flush the active layer. 2) Melting ground ice releases DOM. 3) Ground ice meltwater leaches DOM from sedimentary OM upon permafrost thaw on land. 4) DOM is leached from sedimentary OM upon contact with sea water. The latter three will mobilize old OM which is believed to be highly bioavailable (see Vonk et al., 2013a, b). References: Dubinenkov, I., Flerus, R., Schmitt-Kopplin, P., Kattner, G., Koch, B.P., 2015. Origin-specific molecular signatures of dissolved organic matter in the Lena Delta. Biogeochemistry 123, 1-14. Fritz, M., Opel, T., Tanski, G., Herzschuh, U., Meyer, H., Eulenburg, A., Lantuit, H., 2015. Dissolved organic carbon (DOC) in Arctic ground ice. The Cryosphere 9, 737-752. Vonk, J.E., Mann, P.J., Davydov, S., Davydova, A., Spencer, R.G.M., Schade, J., Sobczak, W.V., Zimov, N., Zimov, S., Bulygina, E., Eglinton, T.I., Holmes, R.M., 2013a. High biolability of ancient permafrost carbon upon thaw. Geophysical Research Letters 40, 2689-2693. Vonk, J.E., Mann, P.J., Dowdy, K.L., Davydova, A., Davydov, S.P., Zimov, N., Spencer, R.G.M., Bulygina, E.B., Eglinton, T.I., Holmes, R.M., 2013b. Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw. Environmental Research Letters 8, 035023

Long-Term Effects of the Individual Placement and Support Intervention on Employment Status: 6-Year Follow-Up of a Randomized Controlled Trial

People with mental illness often experience difficulties with reintegration into the workplace, although employment is known to assist these individuals in their recovery process. Traditional approaches of "first train, then place" have been recently replaced by supported employment (SE) methods that carry strategy of "first place, then train." Individual placement and support (IPS) is one of the best-studied methods of SE, which core principles are individualized assistance in rapid job search with consequent placement in a paid employment position. A considerable amount of high-quality evidence supported the superiority of IPS over conventional methods in providing improved employment rates, longer job tenure, as well as higher salaries in competitive job markets. Nonetheless, our knowledge about the IPS-mediated long-term effects is limited. This non-interventional follow-up study of a previously published randomized controlled trial (RCT) called ZhEPP aimed to understand the long-term impact of IPS after 6 years since the initial intervention. Participants from the ZhEPP trial, where 250 disability pensioners with mental illnesses were randomized into either IPS intervention group or treatment as usual group (TAU), were invited to face-to-face interviews, during which employment status, job tenure, workload, and salaries were assessed. One hundred and fourteen individuals agreed to participate in this follow-up study. Although during the first 2 years post-intervention, the IPS group had higher employment rates (40% (IPS) vs. 28% (TAU), p < 0.05 at 24 months), these differences disappeared by the time of follow-up assessments (72 months). The results indicated no substantial differences in primary outcome measures between IPS and TAU groups: employment rate (36 vs. 33%), workload (10.57 vs. 10.07 h per week), job tenure (29 vs. 28 months), and salary (20.21CHF vs. 25.02 CHF). These findings provide important insights regarding the long-term effects of IPS among individuals with mental health illnesses. Further research is required to advance the current knowledge about IPS intervention and its years-long impact

Assessing the Local Nature of Arctic Nearhore Environments using Bio-Oprical Parameters. A Case Study from Herschel Island, Western Canadian Arctic

The Arctic is subject to substantial changes due to the greenhouse gas induced climate change. While impacts on lateral transport pathways such as rivers have been extensively studied yet, there is little knowledge about ecological and geological reactions of nearshore environments, even though those are of high importance for native communities. Here we present an extensive dataset of bio-optical parameters collected in the nearshore zone of Herschel Island, western Canadian Arctic in summer 2018, containing suspended particulate matter concentration (SPM), turbidity, sea surface temperature (SST) and the water leaving reflectance (RRS). Our results clearly indicate that recently published bio-optical models using validation data from the Canadian Beaufort Shelf are not able to reflect the local nature of Herschel Islands nearshore environment and strongly underestimate reality. Accurate bio-optical models of Arctic nearshore environments are necessary to enhance the knowledge of Arctic marine dynamics and recently published bio-optical models need an adjustment