Mires in the Maluti Mountains of Lesotho.

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Landscape-level vegetation conversion and biodiversity improvement after 33 years of restoration management in the Drentsche Aa brook valley

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Hydrological landscape settings of base-rich fen mires and fen meadows:an overview

Question: Why do similar fen meadow communities occur in different landscapes? How does the hydrological system sustain base-rich fen mires and fen meadows? Location: Interdunal wetlands and heathland pools in The Netherlands, percolation mires in Germany, Poland, and Siberia, and calcareous spring fens in the High Tatra, Slovakia. Methods: This review presents an overview of the hydrological conditions of fen mires and fen meadows that are highly valued in nature conservation due to their high biodiversity and the occurrence of many Red List species. Fen types covered in this review include: (1) small hydrological systems in young calcareous dune areas, and (2) small hydrological systems in decalcified old cover sand areas in The Netherlands; (3) large hydrological systems in river valleys in Central-Europe and western-Siberia, and (4) large hydrological systems of small calcareous spring fens with active precipitation of travertine in mountain areas of Slovakia. Results: Different landscape types can sustain similar nutrient poor and base-rich habitats required by endangered fen meadow species. The hydrological systems of these landscapes are very different in size, but their groundwater flow pattern is remarkably similar. Paleo-ecological research showed that travertine forming fen vegetation types persisted in German lowland percolation mires from 6000 to 3000 BP. Similar vegetation types can still be found in small mountain mires in the Slovak Republic. Small pools in such mires form a cascade of surface water bodies that stimulate travertine formation in various ways. Travertine deposition prevents acidification of the mire and sustains populations of basiphilous species that elsewhere in Europe are highly endangered. Conclusion: Very different hydrological landscape settings can maintain a regular flow of groundwater through the top soil generating similar base-rich site conditions. This is why some fen species occur in very different landscape types, ranging from mineral interdunal wetlands to mountain mires

8x8 Reconfigurable quantum photonic processor based on silicon nitride waveguides

The development of large-scale optical quantum information processing circuits ground on the stability and reconfigurability enabled by integrated photonics. We demonstrate a reconfigurable 8x8 integrated linear optical network based on silicon nitride waveguides for quantum information processing. Our processor implements a novel optical architecture enabling any arbitrary linear transformation and constitutes the largest programmable circuit reported so far on this platform. We validate a variety of photonic quantum information processing primitives, in the form of Hong-Ou-Mandel interference, bosonic coalescence/anticoalescence and high-dimensional single-photon quantum gates. We achieve fidelities that clearly demonstrate the promising future for large-scale photonic quantum information processing using low-loss silicon nitride.Comment: Added supplementary materials, extended introduction, new figures, results unchange

Cache as ca$h can

In this contribution several caching strategies for the World Wide Weba re studied. Special attention is paid to the so-called proxy placement, i.e. placing of caches on carefully selected nodes in the network near to the end users

Ecohydrological analysis of a South African through-flow mire:Vankervelsvlei revisited

The Vankervelsvlei mire has one of the thickest peat deposits (more than 10 m) in South Africa, which started accumulating before 7000 BP. Two previous studies on the hydrological system that sustains the wetland reached inconsistent conclusions and disagreed strongly on the main sources of water feeding the wetland. One suggested that the wetland is fed by groundwater discharging from the underlying Table Mountain Group Aquifer, while the other proposed that the wetland is a perched system fed only by precipitation water. We tried to reconcile these discrepancies by measuring water table, hydraulic pressure and temperature in the peat profile and analysing the ionic composition of the groundwater. We also carried out radiocarbon dating (14C) of groundwater and surface water. Our results showed that both groundwater and surface water are relatively young (<50 years) and that V ankervelsvlei is hydrologically a through-flow system with (local) mineral-poor groundwater entering the mire, possibly from a catchment located in the dunes that lie to the south-east. The groundwater exits the mire at the opposite (northern) side. Our findings do not support either the hypothesis that the mire is fed by groundwater from a deep regional aquifer, or the notion that it is sustained exclusively by precipitation wate

Functional Interactions between KCNE1 C-Terminus and the KCNQ1 Channel

The KCNE1 gene product (minK protein) associates with the cardiac KvLQT1 potassium channel (encoded by KCNQ1) to create the cardiac slowly activating delayed rectifier, IKs. Mutations throughout both genes are linked to the hereditary cardiac arrhythmias in the Long QT Syndrome (LQTS). KCNE1 exerts its specific regulation of KCNQ1 activation via interactions between membrane-spanning segments of the two proteins. Less detailed attention has been focused on the role of the KCNE1 C-terminus in regulating channel behavior. We analyzed the effects of an LQT5 point mutation (D76N) and the truncation of the entire C-terminus (Δ70) on channel regulation, assembly and interaction. Both mutations significantly shifted voltage dependence of activation in the depolarizing direction and decreased IKs current density. They also accelerated rates of channel deactivation but notably, did not affect activation kinetics. Truncation of the C-terminus reduced the apparent affinity of KCNE1 for KCNQ1, resulting in impaired channel formation and presentation of KCNQ1/KCNE1 complexes to the surface. Complete saturation of KCNQ1 channels with KCNE1-Δ70 could be achieved by relative over-expression of the KCNE subunit. Rate-dependent facilitation of K+ conductance, a key property of IKs that enables action potential shortening at higher heart rates, was defective for both KCNE1 C-terminal mutations, and may contribute to the clinical phenotype of arrhythmias triggered by heart rate elevations during exercise in LQTS mutations. These results support several roles for KCNE1 C-terminus interaction with KCNQ1: regulation of channel assembly, open-state destabilization, and kinetics of channel deactivation