Middle and Late Pleistocene environmental history of the Marsworth area, south-central England

To elucidate the Middle and Late Pleistocene environmental history of south-central England, we report the stratigraphy, sedimentology, palaeoecology and geochronology of some deposits near the foot of the Chiltern Hills scarp at Marsworth, Buckinghamshire. The Marsworth site is important because its sedimentary sequences contain a rich record of warm stages and cold stages, and it lies close to the Anglian glacial limit. Critical to its history are the origin and age of a brown pebbly silty clay (diamicton) previously interpreted as weathered till. The deposits described infill a river channel incised into chalk bedrock. They comprise clayey, silty and gravelly sediments, many containing locally derived chalk and some with molluscan, ostracod and vertebrate remains. Most of the deposits are readily attributed to periglacial and fluvial processes, and some are dated by optically stimulated luminescence to Marine Isotope Stage (MIS) 6. Although our sedimentological data do not discriminate between a glacial or periglacial interpretation of the diamicton, amino-acid dating of three molluscan taxa from beneath it indicates that it is younger than MIS 9 and older than MIS 5e. This makes a glacial interpretation unlikely, and we interpret the diamicton as a periglacial slope deposit. The Pleistocene history reconstructed for Marsworth identifies four key elements: (1) Anglian glaciation during MIS 12 closely approached Marsworth, introducing far-travelled pebbles such as Rhaxella chert and possibly some fine sand minerals into the area. (2) Interglacial environments inferred from fluvial sediments during MIS 7 varied from fully interglacial conditions during sub-stages 7e and 7c, cool temperate conditions during sub-stage 7b or 7a, temperate conditions similar to those today in central England towards the end of the interglacial, and cool temperate conditions during sub-stage 7a. (3) Periglacial activity during MIS 6 involved thermal contraction cracking, permafrost development, fracturing of chalk bedrock, fluvial activity, slopewash, mass movement and deposition of loess and coversand. (4) Fully interglacial conditions during sub-stage 5e led to renewed fluvial activity, soil formation and acidic weathering

Heteroepitaxy of La2O3La_2O_3 and La2−xYxO3La_{2-x}Y_xO_3 on GaAs (111)A by Atomic Layer Deposition: Achieving Low Interface Trap Density

GaAs metal–oxide–semiconductor devices historically suffer from Fermi-level pinning, which is mainly due to the high trap density of states at the oxide/GaAs interface. In this work, we present a new way of passivating the interface trap states by growing an epitaxial layer of high-k dielectric oxide, $La_{2–x}Y_xO_3$, on GaAs(111)A. High-quality epitaxial $La_{2–x}Y_xO_3$ thin films are achieved by an ex situ atomic layer deposition (ALD) process, and GaAs MOS capacitors made from this epitaxial structure show very good interface quality with small frequency dispersion and low interface trap densities $(D_{it})$. In particular, the $La_2O_3$/GaAs interface, which has a lattice mismatch of only 0.04%, shows very low $D_{it}$ in the GaAs bandgap, below $3 × 10^{11} cm^{–2} eV^{–1}$ near the conduction band edge. The $La_2O_3$/GaAs capacitors also show the lowest frequency dispersion of any dielectric on GaAs. This is the first achievement of such low trap densities for oxides on GaAs.Chemistry and Chemical Biolog

Managing tensions and paradoxes between stakeholders in a complex project context: Case study and model proposal

Stakeholder (SH) management has recently undertaken a turn from the traditional management "of" to managing "for" and "with" SH. Relating to this relational trend, identification and management tensions between SH is an important area of study. Indeed, from how to live with and/or resolve or not those tensions depend on the possibility of building the most beneficial cooperation possible between SH for the continuation of the project, to obtain win-win results, and to promote the shared value and common good. For this purpose, a theoretical model is suggested, based on the approaches of paradoxes and conventionalist economy of worth, supporting the identification of tensions between SH and their justifications, and the clarification it helps to bring as to win-win or shared value outcomes, or the absence of such, in the context of a complex project. The suggested model is then used in an exploratory case study. The goal is to assess its relevance, usefulness, and quality. Two theoretical contributions emerge from the data analyzed: 1) several tensions over various categories (allegiance, dimensional, temporal, learning, performance and spatial) can draw on the same justifications (rationale that opposes industrial and domestic conventions); 2) prioritization of tension categories can make it easier to resolve them. © 2016 Editora Mundos Sociais. All rights reserved