Thermal disorder in ionic crystals

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Preliminary study of the sedimentation of Lake St. Clair from minor river and stream tributaries

Sediment samples collected from the minor tributary streams and rivers of Lake St. Clair were analyzed to determine if there were any distinct mineral assemblages within the <64 micrometer size fraction. These assemblages could then identify lake sediment provenances. Mineral assemblages were identified for all the streams and rivers by x-ray dffraction analysis, and were found to be uniform in composition. It is suggested that the sources for the suspended and bottom sediments of the streams and rivers have similar compositions, such as that of a uniform till plain. The distribution patterns of the fluvially transported sediments in the lake can not be determined solely on the basis of the composition of the <64 micrometer size fraction.No embarg

Carbon Monoxide Oxidation on Model Planar Titania Supported Platinum Nanoparticles Catalyst

A high-throughput (parallel) thermographic screening methodology was developed to enable the measurements of the particle size and support influence on heterogeneous catalysts. A high throughput screening chip has been used to establish the catalytic activity of titania supported platinum nanoparticles catalyst for CO oxidation reaction. The catalytic activity of Pt nanoparticles between 1.3 to 7.8 nm has been investigated for CO conversion at a pressure of 0.11 and 1.1 mbar with O2:CO ratio of 1:1 at 80 °C and 0.6, 1.1 and 2.4 mbar at O2:CO ratio of 1:1 at 240 °C. At these experimental conditions, there was an increase in the TOF with decreasing particle size for instance, at 80 °C and O2:CO ratio of 1:1, total pressure of 0.11 and 1.1 mbar, the TOF increased from 0.01 s–1 to 0.171 s–1 with decreasing Pt particle size from 7.8 to 1.3 nm, respectively. However, Pt nanoparticles catalyst displayed higher activity at higher temperature, for example, the TOF increased from 3.312 s–1 to 4.355 s–1 at O2:CO ratio of 1:1, total pressure of 0.6 and 1.1 mbar, respectively, for Pt particle size of 1.3 nm in agreement with the previous reports. Results show that CO oxidation on titania supported Pt nanoparticles catalyst is particle size dependent. On the other hand, findings from XPS measurements show no major change in the particle size after the reaction thus, reflecting the stability of Pt particles. While there is no apparent consensus in the literature reports on the activity trend with particle size for this system, these findings are consistent with most of the previously reported findings. Keywords: platinum; titania; nanoparticles; thermography; CO oxidation

Entanglement Wedge Reconstruction via Universal Recovery Channels

We apply and extend the theory of universal recovery channels from quantum information theory to address the problem of entanglement wedge reconstruction in AdS/CFT. It has recently been proposed that any low-energy local bulk operators in a CFT boundary region's entanglement wedge can be reconstructed on that boundary region itself. Existing work arguing for this proposal relies on algebraic consequences of the exact equivalence between bulk and boundary relative entropies, namely the theory of operator algebra quantum error correction. However, bulk and boundary relative entropies are only approximately equal in bulk effective field theory, and in similar situations it is known that predictions from exact entropic equalities can be qualitatively incorrect. The framework of universal recovery channels provides a robust demonstration of the entanglement wedge reconstruction conjecture in addition to new physical insights. Most notably, we find that a bulk operator acting in a given boundary region's entanglement wedge can be expressed as the response of the boundary region's modular Hamiltonian to a perturbation of the bulk state in the direction of the bulk operator. This formula can be interpreted as a noncommutative version of Bayes' rule that attempts to undo the noise induced by restricting to only a portion of the boundary, and has an integral representation in terms of modular flows. To reach these conclusions, we extend the theory of universal recovery channels to finite-dimensional operator algebras and demonstrate that recovery channels approximately preserve the multiplicative structure of the operator algebra.Comment: 16 pages, 3 figures. v4: Generalized approximate recovery of 2-point functions to arbitrary correlation functions. Clarified relation to previous work. Added Geoffrey Penington as co-autho

Thermally stable low current consuming gallium and germanium chalcogenides for consumer and automotive memory applications

The phase change technology behind rewritable optical disks and the latest generation of electronic memories has provided clear commercial and technological advances for the field of data storage, by virtue of the many well known attributes, in particular scaling, cycling endurance and speed, that chalcogenide materials offer. While the switching power and current consumption of established germanium antimony telluride based memory cells are a major factor in chip design in real world applications, often the thermal stability of the device can be a major obstacle in the path to the full commercialisation. In this work we describe our research in material discovery and characterization for the purpose of identifying more thermally stable chalcogenides for applications in PCRAM

Les moyens d'acquérir dans les sociétés « transégalitaires »

International audienc

Winter ecology of specialist and generalist morphs of European whitefish, Coregonus lavaretus, in subarctic Northern Europe

European whitefish is a model species for adaptive radiation of fishes in temperate and subarctic lakes. In northern Europe the most commonly observed morphotypes are a generalist (LSR) morph and a pelagic specialist (DR) morph. The evolution of a pelagic specialist morph is something of an enigma, however, as this region is characterized by long, dark winters with pelagic primary production limited to a brief window in late summer. We conducted the first winter-based study of polymorphic whitefish populations to determine the winter ecology of both morphs, and we combined seasonal diet and stable isotope analysis with several proxies of condition in three polymorphic whitefish populations. The generalist LSR morph fed on benthic and pelagic prey in summer but was solely reliant on benthic prey in winter. This was associated with a noticeable but moderate reduction in condition, lipid content and stomach fullness in winter relative to summer. In contrast, the DR whitefish occupied a strict pelagic niche in both seasons. A significant reduction in pelagic prey during winter resulted in severe decrease in condition, lipid content and stomach fullness in DR whitefish in winter relative to summer, with the pelagic morph apparently approaching starvation in winter. We suggest that this divergent approach to seasonal foraging is associated with the divergent life-history traits of both morphs.Peer reviewe

Mangrove and mudflat food webs are segregated across four trophic levels, yet connected by highly mobile top predators

Seascape connectivity is crucial for healthy, resilient ecosystems and fisheries. Yet, our understanding of connectivity in turbid mangrove-lined estuaries—some of the world’s most productive ecosystems—is limited to macrotidal systems, and rarely incorporates highly mobile top predators. We analysed δ13C and δ15N isotope values of 7 primary producers, 24 invertebrate taxa, 13 fishes, 4 birds and 1 reptile to reveal trophic interactions within and between a mangrove and adjacent mudflat in a microtidal system of the Gulf of Paria, Orinoco River estuary. Primary producers, invertebrates and fishes collected within the mangrove were significantly depleted in 13C and 15N compared to those collected on the mudflat. Stable isotope mixing models showed that mangrove-derived carbon was predominantly assimilated by invertebrates (78 ± 5% SE) and fishes (88 ± 11%) sampled in the mangrove. In contrast, invertebrates and fishes sampled in the mudflat derived <21% of their carbon from mangrove sources. Instead, microphytobenthos and phytoplankton underpinned the mudflat food web. Scarlet ibis Eudocimus ruber and yellow-crowned night heron Nyctanassa violacea were also highly associated with mangrove carbon sources. However, osprey Pandion haliaetus, snowy egret Egretta thula and spectacled caiman Caiman crocodilus obtained carbon from both mangrove and mudflat sources, effectively integrating the food webs. The present study demonstrates simultaneous aspects of food web segregation and connectivity, as well as the importance of surveying the entire food web across a range of tidal systems when investigating seascape connectivity