447 research outputs found
The knightly families of Northumberland: a crisis in the early fourteenth century
The way Northumbrian society was created and how it developed during the twelfth and thirteenth centuries, is crucial to the crisis the families faced when war broke out between the kingdoms of England and Scotland. Eighty years of peace and prosperity in the North saw the consolidation of the Norman presence along the border. The Anglo/Norman and Scottish/Norman families formed a single aristocracy, holding estates on both sides of the border and being vassals to both kings. United by language, customs and manners, they formed a homogeneous society. The peace that prevailed for the last eighty years of the Fourteenth century brought prosperity to the region and were 'the golden years' in the history of the North. This peace was shattered in 1296 when, following the events of the Scottish succession, Edward I declared war on Scotland. The northern nobility were at once thrown into a crisis of allegiance. Any choice, inevitably, meant a loss of lands on the other side of the Border. A boundary had suddenly become a frontier, and friends and relatives had became 'the enemy'. All the families of the knightly class, the barons, the lesser nobility and the gentry were involved in, and affected by the war, albeit in different ways. The outbreak of war was followed in 1315 by flooding and bad weather causing a series of bad harvests, leading to famine and high food prices. Coupled with this there was a sheep and cattle murrain, which killed many of the plough oxen thus making recovery difficult. The Black Death in 1348 depleted the population, adding to the economic decline The inactivity of Edward n to the suffering in the north during the Scottish raids of Robert the Bruce led to a rebellion of the lesser landowners under the leadership of Gilbert de Middleton in 1317. This rebellion was to have repercussions forty years later in the form of a collection of escheats known as the Nessfield escheats, named after William de Nessfield, escheator north of Trent. For some, a war, could be the making of their fortunes. Such a person was John de Coupland. By capturing David 1, King of Scots in 1346 at the Battle of Neville’s Cross, he was lavishly rewarded. However, he did not enjoy his good fortune for long, for in 1363 he was murdered by a group of Northumberland knights. The question of whether the knightly families of Northumberland faced a crisis in the early fourteenth century has similarities to the debate over the fate of the knightly class in the thirteenth century. Some historians have suggested that the high cost of knighthood in that period caused a crisis, while an alternative view is that there was no general crisis, but that some families faced difficulties as a result of the mismanagement of their affairs. The question of whether the knightly families of Northumberland faced a crisis in the fourteenth century is explored from the perspectives of the Scottish war, the economy and the political situation
The formation of stoichiometric uranium brannerite (UTi2O6) glass-ceramic composites from the component oxides in a one-pot synthesis
Brannerite glass-ceramic composites have been suggested as suitable wasteform materials for high-actinide content wastes, but the formation of glass-ceramic composites containing stoichiometric uranium brannerite (UTi2O6) has not been well-studied. Uranium brannerite glass-ceramic composites were synthesised at by a one-pot cold-press and sinter route from the component oxides. As a comparison, two further samples were produced using an alkoxide-nitrate route. A range of compositions with varying molar ratios of uranium and titanium oxides (from 1:2 to 1:3.20) were synthesised, with a range of different heat treatments (1200 °C for 12–48 h, and 1250 °C for 12 h). All compositions were analysed by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray near-edge spectroscopy, and found to contain UTi2O6 as the majority crystalline phase forming within a glass matrix of nominal stoichiometry Na2AlBSi6O16. In compositions with UO2:TiO2 ratios of 1:2 and 1:2.28, particles of UO2 were observed in the glass matrix, likely due to dissolution of TiO2 in the glass phase; this was prevented by the addition of excess TiO2. This work demonstrates the suitability of this system to produce highly durable wasteforms with excellent actinide waste loading, even with a simple one-pot process. Some grains of brannerite consist of a UO2 particle encapsulated in a shell of UTi2O6, suggesting that brannerite crystallises around particles of UO2 until either the UO2 is fully depleted, or the kinetic barrier becomes too large for further diffusion to occur. We propose that the formation of brannerite within glass-ceramic composites at lower temperatures than that for pure ceramic brannerite is caused by an increase in the rate of diffusion of the reactants within the glass
Synthesis and characterisation of high ceramic fraction brannerite (UTi2O6) glass-ceramic composites
Brannerite, UTi2O6, glass-ceramic composites have been prepared, using UO2 and TiO2 as the ceramic phase precursors. A range of cold-press and sinter samples with varying glass:ceramic ratios have been prepared under argon at 1200 °C to investigate the effect of glass content on formation of brannerite. Ceramic brannerite formed well in all compositions, even at low (10% by weight) glass fractions, with UO2 as a minor product. Three further brannerite glass-ceramics have been prepared by hot isostatic pressing to investigate the compatibility of this system to HIPing. The samples HIPed at 1200 °C form brannerite, with UO2 as a minor phase with slightly higher abundance than in the cold-press and sinter samples
An Extended Adaptive Kalman Filter for Real-time State Estimation of Vehicle Handling Dynamics
Solid solubility in the CeTi2O6–CeTiNbO6 system: a multi-element X-ray spectroscopic study
In order to investigate the limits of solid solubility between Ce-brannerite (CeTi2O6) and Ce-aeschynite (CeTiNbO6), materials in the system CeTi2–xNbxO6 have been produced by a solid state route and characterised by XRD and XANES at the Ce L3-, Ti K- and Nb K-edges, including Rietveld method refinements and linear combination fitting. Significant solid solubility was observed at the brannerite end, with near-single-phase brannerite observed for x = 0.2, 0.4, and only minor aeschynite observed where x = 0.6 which was identified as exceeding the limit of solubility of Nb. All Nb was present as Nb5+, with the substitution of Nb5+ into the brannerite structure permitted by the reduction of the same fraction of Ce4+ to Ce3+. This work expands the crystal chemistry of the titanate brannerites, with Ce-site oxidation states of less than 4+ being possible where sufficient charge-balancing species are available on the Ti-site
Structural Relaxation and Frequency Dependent Specific Heat in a Supercooled Liquid
We have studied the relation between the structural relaxation and the
frequency dependent thermal response or the specific heat, , in a
supercooled liquid.
The Mode Coupling Theory (MCT) results are used to obtain
corresponding to different wavevectors. Due to the two-step
relaxation process present in the MCT, an extra peak, in addition to the low
frequency peak, is predicted in specific heat at high frequency.Comment: 14 pages, 13 Figure
A feasibility investigation of laboratory based X-ray absorption spectroscopy in support of nuclear waste management
X-ray Absorption Spectroscopy is a technique of fundamental importance in nuclear waste management, as an element specific probe of speciation, which governs radionuclide solubility, immobilisation and migration. Here, we exploit recent developments in laboratory instrumentation for X-ray Absorption Spectroscopy, based on a Rowland circle geometry with a spherically bent crystal analyser, to demonstrate speciation in prototype ceramic and glass-ceramic waste forms. Laboratory and synchrotron XANES data acquired from the same materials, at the Ce and U L3 edges, were found to be in excellent quantitative agreement. We establish that analysable laboratory XANES data may be acquired, and interpreted for speciation, even from quite dilute absorber concentrations of a few mol%, albeit with data acquisition times of several hours. For materials with suitable absorber concentrations, this approach will enable routine element specific speciation studies to support rapid optimisation of radioactive waste forms and analysis of radiological materials in a purpose designed laboratory, without the risk associated with transport and manipulation at a synchrotron radiation facility
Application of diagnostic techniques to an experimental aircraft fuel rig
An important issue for Aerospace and Defence Systems providers is how to
reduce the risks associated with installing a new Fault Detection Tool (FDT) on a system.
It is highly desirable that some degree of assessment, selection and validation is carried
out before the FDT is integrated with the system. This paper describes the initial phases
of a project to investigate the processes behind the assessment and validation using an
Experimental Aircraft Fuel Rig (referred to as the Advanced Diagnostic Test-bed ADT).
This paper also presents results from preliminary verification and validation work that has
been used on a mathematical model of the ADT, and also some results from some initial
diagnostic technique assessment that has been performed using real experimental data
from the ADT and simulated data from mathematical models
Assessment of weeds of cassava and farmers management practices in Nigeria
Open Access JournalLa concurrence des mauvaises herbes est un obstacle à la rentabilité de la production du manioc. La connaissance des espèces de mauvaises herbes qui affectent négativement la productivité du manioc est essentielle pour une gestion efficace. Une étude a été conduite entre mai et juin 2014 et 2015 pour évaluer les mauvaises herbes dans 200 exploitations agricoles de manioc, dans trois zones agroécologiques au Nigeria. L’Analyse des Correspondances Détendancées (ACD) a permis d’identifier quatre groupes distincts illustrant la variation des espèces de mauvaises herbes parmi les zones agroécologiques. Le pH du sol et la teneur en limon, la durée des jachères, la méthode de culture et la méthode de gestion des mauvaises herbes ont contribué à la variation de la composition des espèces. L’évaluation par les agriculteurs et sur le terrain ont identifié Euphorbia heterophylla, Imperata cylindrica, Aspilia africana, Panicum maximum, Chromolaena odorata, Commelina benghalensis, Digitaria horizontalis, et Rottboellia cochinchinensis comme principales mauvaises herbes du manioc. La gestion de ces mauvaises herbes par les paysans varie à travers les zones, suggérant ainsi que les stratégies de gestion de ces mauvaises herbes devraient être axées sur les zones écologiques. Dans la zone forestière humide, le désherbage à la houe (51,2%) et à la machette (43,0%) étaient les principales méthodes de contrôle. L’utilisation d’herbicides était élevée dans le sud de la savane guinéenne et modérée dans la savane dérivée. L’éducation afin d’accroitre la connaissance des agriculteurs sur la problématique des mauvaises herbes et l’amélioration de leur choix à la fois sur les herbicides appropriés et leur utilisation sans risque est essentielle pour une gestion efficace des mauvaises herbes dans la culture du manioc.
Competition from weeds is an obstacle to profitable cassava production. Knowledge of weed species negatively affecting productivity is essential for effective management. A field evaluation of weeds and management practices was conducted between May and June in 2014 and 2015 in 200 cassava farms in three agroecologies in Nigeria. Detrended Correspondence Analysis identified four distinct clusters depicting variation in weed species composition among the agroecologies. Soil pH and silt content, fallow length, cultivation method, and weed management method contributed to the variation in species composition. Farmers and field evaluations identified Euphorbia heterophylla, Imperata cylindrica, Aspilia africana, Panicum maximum, Chromolaena odorata, Commelina benghalensis, Digitaria horizontalis, and Rottboellia cochinchinensis as major problem weeds in cassava. Farmers’ management of these weeds varied across zones, suggesting that weed management strategies in cassava should be focused on ecological zones. In the Humid forest, hoe-weeding (51.2%) and slashing (43.0%) with machetes were the predominant methods of control. Herbicide use was high in the Southern Guinea Savanna and medium to high in the Derived Savanna (26.3-42.2%). Education to increase farmers’ knowledge of the problematic of weeds and to improve both their choice of appropriate herbicides and their safe use is critical to effective and efficient weed management in cassava
Portomesenteric Vein Thrombosis After Laparoscopic Sleeve Gastrectomy: A Single-Institution Report
Laparoscopic sleeve gastrectomy (LSG) is an effective weight-loss operation. Portomesenteric vein thrombosis (PMVT) is an important complication of LSG. We identified four cases of PMVT after LSG at our institution in women aged 36-47 with BMIs ranging from 44-48 kg/m2. All presented 8-19 days postoperatively. Common symptoms were nausea, vomiting, and abdominal pain. Thrombotic risk factors were previous deep vein thrombosis and oral contraceptive use. Management included therapeutic anti-coagulation, directed thrombolysis, and surgery. Complications were readmission, bowel resection, and bleeding. Discharge recommendations ranged from 3-6 months of anticoagulation using various anticoagulants. No consensus was reached on post-treatment hypercoagulable work up or imaging. All cases required multi-disciplinary approach with Surgery, Interventional Radiology, and Hematology. As PMVT is a rare but potentially morbid complication of LSG, further development of tools that quantify preoperative thrombotic risk and clear guidance regarding use of anticoagulants are needed for prevention and treatment of PMVT following LSG
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