Pressure-resistant intermediate valence in Kondo insulator SmB6

Resonant x-ray emission spectroscopy (RXES) was used to determine the pressure dependence of the f-electron occupancy in the Kondo insulator SmB6. Applied pressure reduces the f-occupancy, but surprisingly, the material maintains a significant divalent character up to a pressure of at least 35 GPa. Thus, the closure of the resistive activation energy gap and onset of magnetic order are not driven by stabilization of an integer valent state. Over the entire pressure range, the material maintains a remarkably stable intermediate valence that can in principle support a nontrivial band structure

Inelastic contribution of the resistivity in the hidden order in URu2Si2

In the hidden order of URu2Si2 the resistivity at very low temperature shows no T^2 behavior above the transition to superconductivity. However, when entering the antiferromagnetic phase, the Fermi liquid behavior is recovered. We discuss the change of the inelastic term when entering the AF phase with pressure considering the temperature dependence of the Grueneisen parameter at ambient pressure and the influence of superconductivity by an extrapolation of high field data.Comment: 5 pages, 2 figures, SCES conference proceedin

Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia

The Estonian Journal of Earth Sciences is an open access journal and applies the Creative Commons Attribution 4.0 International License CC BY to all its papers (http://creativecommons.org/licenses/by/4.0/). The attached file is the published version of the article

The Stellar Parameters and Evolutionary State of the Primary in the d'-Symbiotic System StH\alpha190

We report on a high-resolution, spectroscopic stellar parameter and abundance analysis of a d' symbiotic star: the yellow component of StH\alpha190. This star has recently been discovered, and confirmed here, to be a rapidly rotating (vsini=100 km/s) subgiant, or giant, that exhibits radial-velocity variations of probably at least 40 km/s, indicating the presence of a companion (a white dwarf star). It is found that the cool stellar component has Teff=5300K and log g=3.0. The iron and calcium abundances are close to solar, however, barium is overabundant, relative to Fe and Ca, by about +0.5 dex. The barium enhancement reflects mass-transfer of s-process enriched material when the current white dwarf was an asymptotic giant branch (AGB) star. The past and future evolution of this binary system depends critically on its current orbital period, which is not yet known. Concerted and frequent radial-velocity measurements are needed to provide crucial physical constraints to this d' symbiotic system.Comment: 9 pages, 1 table, 3 figures. In press to Astrophysical Journal Letter

The origin of green icebergs in Antarctica

A comparison of samples from a translucent green iceberg with a core from the Ronne Ice Shelf revealed an excellent agreement in isotopic composition, crystal structure, and incorporated sediment particles. Marine shelf ice which constitutes the basal portion of some ice shelves is considered to be the source of green icebergs. It most likely results from "ice pump" processes which produce large amounts of ice platelets in the water column beneath ice shelves. These subsequently accumulate and become compacted into bubble-free, desalinated ice. Iceberg and drift-buoy trajectories indicate that green icebergs observed in the Weddell Sea originate from the Amery Ice Shelf rather than from the Ronne Ice Shelf, although the latter ice shelf is also a potential source

Rare earth elements (REEs) in vertebrate microremains from the upper Pridoli Ohesaare beds of Saaremaa Island, Estonia: geochemical clues to palaeoenvironment c

This is an open access article, available to all readers online, licensed under the Creative Commons Attribution 4.0 International License (CC BY; http://creativecommons.org/licenses/by/4.0/). The attached file is the published version of the article

Field Reentrance of the Hidden Order State of URu2Si2 under Pressure

Combination of neutron scattering and thermal expansion measurements under pressure shows that the so-called hidden order phase of URu2Si2 reenters in magnetic field when antiferromagnetism (AF) collapses at H_AF (T). Macroscopic pressure studies of the HO-AF boundaries were realized at different pressures via thermal expansion measurements under magnetic field using a strain gauge. Microscopic proof at a given pressure is the reappearance of the resonance at Q_0=(1,0,0) under field which is correlated with the collapse of the AF Bragg reflections at Q_0.Comment: 5 pages, 6 figures, accepted for publication in J. Phys. Soc. Jp

The distribution of pond snail communities across a landscape: separating out the influence of spatial position from local habitat quality for ponds in south-east Northumberland, UK

Ponds support a rich biodiversity because the heterogeneity of individual ponds creates, at the landscape scale, a diversity of habitats for wildlife. The distribution of pond animals and plants will be influenced by both the local conditions within a pond and the spatial distribution of ponds across the landscape. Separating out the local from the spatial is difficult because the two are often linked. Pond snails are likely to be affected by both local conditions, e.g. water hardness, and spatial patterns, e.g. distance between ponds, but studies of snail communities struggle distinguishing between the two. In this study, communities of snails were recorded from 52 ponds in a biogeographically coherent landscape in north-east England. The distribution of snail communities was compared to local environments characterised by the macrophyte communities within each pond and to the spatial pattern of ponds throughout the landscape. Mantel tests were used to partial out the local versus the landscape respective influences. Snail communities became more similar in ponds that were closer together and in ponds with similar macrophyte communities as both the local and the landscape scale were important for this group of animals. Data were collected from several types of ponds, including those created on nature reserves specifically for wildlife, old field ponds (at least 150 years old) primarily created for watering livestock and subsidence ponds outside protected areas or amongst coastal dunes. No one pond type supported all the species. Larger, deeper ponds on nature reserves had the highest numbers of species within individual ponds but shallow, temporary sites on farm land supported a distinct temporary water fauna. The conservation of pond snails in this region requires a diversity of pond types rather than one idealised type and ponds scattered throughout the area at a variety of sites, not just concentrated on nature reserves