Crystal Field, Magnetic Anisotropy and Excitations in Rare-Earth Hexaborides

We clarify the role of crystalline electric field (CEF) induced magnetic anisotropy in the ground state and spin-wave spectrum of cubic rare-earth materials with dominating isotropic magnetic exchange interactions. In particular we study the hexaboride NdB_6 which is shown to exhibit strong spin-quadrupolar coupling. The CEF scheme is analyzed and a non-collinear magnetization response is found. The spin orientation in the antiferromagnetically ordered ground-state is identified. Moreover, the spin excitations are evaluated and in agreement with inelastic neutron scattering a suppression of one of the two magnetic modes in the strong-coupling regime is predicted.Comment: 4 pages, 1 eps-figur

The impact of fuel properties on the emissions from the combustion of biomass and other solid fuels in a fixed bed domestic stove

Experimental results are presented on the emissions from a single combustion chamber stove burning wood, coal and processed fuels. This technique was used to permit comparisons to be made of the influence of different fuel types without it being influenced by the effects of secondary combustion. Measurements were made of CO, NOx and fine particulates during the major phases of combustion, namely flaming and smouldering. Measurements of the particulates were made in two ways: firstly using a gravimetric total particulate measurement and secondly using a cyclone technique to give PM2.5 and PM10 size fractions. Smoke emissions from the different fuels were very dependent on the phase of combustion especially for the total particulate results, where flaming phase emissions were much higher than in the smouldering phase. It was found that the particulate emission factors for the wood fuels were dependent on the volatile content whilst the coals followed a different pattern. NOx was linearly dependent on the fuel-N content for all the fuel types, but the relationship for biomass is different from that for coal. CO emissions were very dependent on the combustion phase

Automated mapping of the seasonal evolution of surface meltwater and its links to climate on the Amery Ice Shelf, Antarctica

Surface meltwater is widespread around the Antarctic Ice Sheet margin and has the potential to influence ice shelf stability, ice flow and ice–albedo feedbacks. Our understanding of the seasonal and multi-year evolution of Antarctic surface meltwater is limited. Attempts to generate robust meltwater cover time series have largely been constrained by computational expense or limited ice surface visibility associated with mapping from optical satellite imagery. Here, we add a novel method for calculating visibility metrics to an existing meltwater detection method within Google Earth Engine. This enables us to quantify uncertainty induced by cloud cover and variable image data coverage, allowing time series of surface meltwater area to be automatically generated over large spatial and temporal scales. We demonstrate our method on the Amery Ice Shelf region of East Antarctica, analysing 4164 Landsat 7 and 8 optical images between 2005 and 2020. Results show high interannual variability in surface meltwater cover, with mapped cumulative lake area totals ranging from 384 to 3898 km2 per melt season. By incorporating image visibility assessments, however, we estimate that cumulative total lake areas are on average 42 % higher than minimum mapped values. We show that modelled melt predictions from a regional climate model provide a good indication of lake cover in the Amery region and that annual lake coverage is typically highest in years with a negative austral summer SAM index. Our results demonstrate that our method could be scaled up to generate a multi-year time series record of surface water extent from optical imagery at a continent-wide scale

Stem cell factor (SCF) and c-kit in the ovine fetal testis in normal and nutrition perturbed pregnancies

Stem cell factor (SCF) and c-kit in the ovine fetal testis in normal and nutrition perturbed pregnancie

Coral cities of the deep. Species–habitat associations on the Mingulay Reef Complex

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Low energy pre-blended mortars: Part 2 – Production and characterisation of mortars using a novel lime drying technique

The presence of free water in mortars destined for silo or bagged storage can lead to the degradation of the binder phase. Such water may be present as a result of using wet, as-delivered sand or as a consequence of prior processes such as de-activation of Roman cement. Thus, water must be removed from the system prior to storage. Part 1 of this paper describes the control of a technique by which quicklime is added to the wet system which principally dries it by both slaking the quicklime and evaporation as a consequence of the exothermic slaking reaction. Two examples of mortars are presented in which excess water is removed from the system by the inclusion of quicklime. In the first, the water is present in the as-delivered sand and the binder is a combination of the slaked lime and ggbs. In the second, the water remains after pre-hydration of a Roman cement which is a process to retard its rapid setting characteristics. It is shown that optimally dried mortars are not subject to degradation following storage of both mortar types

A study of smoke formation from wood combustion

Aerosol time of flight mass spectrometry (ATOFMS) was used to analyse the particles emitted during the flaming and smouldering phases of the combustion of samples of hard and soft woods. Eugenol and furfural were also burned and using results from previous work of the authors, they have been shown to be useful proxies for initial wood combustion products. The ratios of elementary carbon to total carbon in the particles were similar for both the woods and for eugenol. The ATOFMS spectra of most of the particles were consistent with the presence of soot precursor constituents along with oxygen containing fragments. Most particle diameters were less than 2.5. μm, with the greatest concentration of <. 0.12. μm

Using the past to constrain the future: how the palaeorecord can improve estimates of global warming

Climate sensitivity is defined as the change in global mean equilibrium temperature after a doubling of atmospheric CO2 concentration and provides a simple measure of global warming. An early estimate of climate sensitivity, 1.5-4.5{\deg}C, has changed little subsequently, including the latest assessment by the Intergovernmental Panel on Climate Change. The persistence of such large uncertainties in this simple measure casts doubt on our understanding of the mechanisms of climate change and our ability to predict the response of the climate system to future perturbations. This has motivated continued attempts to constrain the range with climate data, alone or in conjunction with models. The majority of studies use data from the instrumental period (post-1850) but recent work has made use of information about the large climate changes experienced in the geological past. In this review, we first outline approaches that estimate climate sensitivity using instrumental climate observations and then summarise attempts to use the record of climate change on geological timescales. We examine the limitations of these studies and suggest ways in which the power of the palaeoclimate record could be better used to reduce uncertainties in our predictions of climate sensitivity.Comment: The final, definitive version of this paper has been published in Progress in Physical Geography, 31(5), 2007 by SAGE Publications Ltd, All rights reserved. \c{opyright} 2007 Edwards, Crucifix and Harriso

A tale of two capitalisms: preliminary spatial and historical comparisons of homicide rates in Western Europe and the USA

This article examines comparative homicide rates in the United States and Western Europe in an era of increasingly globalized neoliberal economics. The main finding of this preliminary analysis is that historical and spatial correlations between distinct forms of political economy and homicide rates are consistent enough to suggest that social democratic regimes are more successful at fostering the socio-cultural conditions necessary for reduced homicide rates. Thus Western Europe and all continents and nations should approach the importation of American neo-liberal economic policies with extreme caution. The article concludes by suggesting that the indirect but crucial causal connection between political economy and homicide rates, prematurely pushed into the background of criminological thought during the ‘cultural turn’, should be returned to the foreground