Electron traps in rutile

Undoped samples of single crystal rutile and rutile powder have been studied by the methods of photoluminescence, thermoluminescence and thermally stimulated conductivity. Crystal samples doped with chromium, iron, manganese, cobalt and nickel and powder samples doped with chromium and iron were also studied. Additionally capacitance-voltage, current-voltage and deep level transient spectroscopy measurements were made on Schottky diodes fabricated on rutile made semiconducting by reduction and niobium doping. Undoped, chromium and nickel doped samples all showed one form of PL temperature dependence in which the luminescence was quenched above 190 K. Iron, cobalt and manganese doped samples showed a different dependence in which the intensity decreased from 80 K. The chromium doped powders showed an increase in photoluminescence intensity with chromium doping which supports the view of several workers that chromium provides the luminescence centre in rutile. Evidence was found in thermoluminescence spectra for nine different trapping levels. Thermoluminescence measurements on powders indicated that the spectra were composed of the same peaks found in the crystal samples, although they were not distinct. DLTS spectra from a niobium doped rutile crystal showed one dominant maximum. The variation of this maximum with the DLTS rate window gave an activation energy and a capture cross-section in excellent agreement with the values for the dominant TSL peak and suggests that the simple insulator model used for TSL analysis applies well to rutile. The DLTS result allows the results for trap depths derived from TSL measurements to be viewed with some confidence

The created stone: chemical and archaeological perspectives on the colour and material properties of early Egyptian glass, 1500-1200 B.C.

The Late Bronze Age in Western Asia and Egypt witnessed an explosion in the production of so-called 'vitreous materials', in particular the earliest glass. From its outset, this material appeared in an enormous variety of colours and colour combinations, the manufacture of which demanded a high degree of technological know-how. The unique properties of glass also rapidly came to the fore, most notably the potential of glass to be worked while hot. Archaeometric research into early Egyptian glass has tended to focus on chemical and isotopic analysis as a means to assign provenance to its raw ingredients. To this end, the use of a technique new to archaeology, ToF-SIMS, is developed here in order to investigate the origin of the colorant opacifiers used in glass production. But questions about manufacturing technology and stages of production are also vital to an understanding of the role and perception of glass, and the aforementioned technique is complemented by electron microprobe analysis, revealing a surprising complexity of production, primarily related to coloration. Furthermore, it has been argued that the terms used to refer to glass in epigraphic sources indicate that it was primarily produced in order to imitate, or substitute for, precious stones of value in Late Bronze Age Egypt and Mesopotamia (primarily lapis lazuli, carnelian and turquoise). Recent research into the archaeological and ethnographic understanding of colour naming and classification is applied to these sources along with an investigation of the material properties of glass itself. It is suggested that, far from being an imitation, the artificiality of glass - as a man-made material - was deliberately, sometimes spectacularly, proclaimed. Central to this is the use of colour, in particular in terms of transformation, and the aforementioned complexity of production. It is argued that only through combining the numerous approaches to the evidence taken here - scientific, linguistic-historical, and archaeological - can the perception of glass, and the motivations behind its production, be determined

Grounding of Human Environments and Activities for Autonomous Robots

With the recent proliferation of robotic applications in domestic and industrial scenarios, it is vital for robots to continually learn about their environments and about the humans they share their environments with. In this paper, we present a framework for autonomous, unsupervised learning from various sensory sources of useful human ‘concepts’; including colours, people names, usable objects and simple activities. This is achieved by integrating state-of-the-art object segmentation, pose estimation, activity analysis and language grounding into a continual learning framework. Learned concepts are grounded to natural language if commentary is available, allowing the robot to communicate in a human-understandable way. We show, using a challenging, real-world dataset of human activities, that our framework is able to extract useful concepts, ground natural language descriptions to them, and, as a proof-of-concept, to generate simple sentences from templates to describe people and activities

Oral iron exacerbates colitis and influences the intestinal microbiome

Inflammatory bowel disease (IBD) is associated with anaemia and oral iron replacement to correct this can be problematic, intensifying inflammation and tissue damage. The intestinal microbiota also plays a key role in the pathogenesis of IBD, and iron supplementation likely influences gut bacterial diversity in patients with IBD. Here, we assessed the impact of dietary iron, using chow diets containing either 100, 200 or 400 ppm, fed ad libitum to adult female C57BL/6 mice in the presence or absence of colitis induced using dextran sulfate sodium (DSS), on (i) clinical and histological severity of acute DSS-induced colitis, and (ii) faecal microbial diversity, as assessed by sequencing the V4 region of 16S rRNA. Increasing or decreasing dietary iron concentration from the standard 200 ppm exacerbated both clinical and histological severity of DSS-induced colitis. DSS-treated mice provided only half the standard levels of iron ad libitum (i.e. chow containing 100 ppm iron) lost more body weight than those receiving double the amount of standard iron (i.e. 400 ppm); p<0.01. Faecal calprotectin levels were significantly increased in the presence of colitis in those consuming 100 ppm iron at day 8 (5.94-fold) versus day-10 group (4.14-fold) (p<0.05), and for the 400 ppm day-8 group (8.17-fold) versus day-10 group (4.44-fold) (p<0.001). In the presence of colitis, dietary iron at 400 ppm resulted in a significant reduction in faecal abundance of Firmicutes and Bacteroidetes, and increase of Proteobacteria, changes which were not observed with lower dietary intake of iron at 100 ppm. Overall, altering dietary iron intake exacerbated DSS-induced colitis; increasing the iron content of the diet also led to changes in intestinal bacteria diversity and composition after colitis was induced with DSS

Dispersion strengthening in vanadium microalloyed steels processed by simulated thin slab casting and direct charging. Part 2 - chemical characterisation of dispersion strengthening precipitates

The composition of the sub-15 nm particles in six related vanadium high strength low alloy steels, made by simulated thin slab direct charged casting, has been determined using electron energy loss spectroscopy (EELS). Such particles are considered to be responsible for dispersion hardening. For the first time, particles down to 4 nm in size have had their composition fully determined. In all the steels, the particles were nitrogen and vanadium rich and possibly slightly sub-stoichiometric carbonitrides. Equilibrium thermodynamics predicted much higher carbon to metal atomic ratios than observed in all cases so that kinetics and mechanical deformation clearly control the precipitation process. Thus it is important to formulate the steel with this in mind

Nitrogen cycle disruption through the application of de-icing salts on upland highways

It is hypothesized that episodic introductions of road salt severely disrupt the soil nitrogen cycle at a range of spatial and temporal scales. A field-scale study has confirmed impacts on the nitrogen cycle in soil, soil solution and river samples. There is evidence that ammonium-N retention on cation exchange sites has been reduced by the presence of sodium ions, and that ammonium-N has been flushed from the exchange sites. Increases in soil pH have been caused in naturally acidic uplands. These have enhanced mineralization of organic-N, especially nitrification, leading to a reduction in the mineralizable-N pool of roadside soils. There is evidence to support the hypothesis that organic matter content has been lowered over decades either through desorption or dispersal processes. Multiple drivers are identified that contribute to the disruption of nitrogen cycling processes, but their relative importance is difficult to quantify unequivocally. The influence of road salt on soil and soil solution declines with distance from the highway, but impacts on water chemistry in a local stream are still strongly evident at some distance from the road

Interaction Properties of the Periodic and Step-like Solutions of the Double-Sine-Gordon Equation

The periodic and step-like solutions of the double-Sine-Gordon equation are investigated, with different initial conditions and for various values of the potential parameter $\epsilon$. We plot energy and force diagrams, as functions of the inter-soliton distance for such solutions. This allows us to consider our system as an interacting many-body system in 1+1 dimension. We therefore plot state diagrams (pressure vs. average density) for step-like as well as periodic solutions. Step-like solutions are shown to behave similarly to their counterparts in the Sine-Gordon system. However, periodic solutions show a fundamentally different behavior as the parameter $\epsilon$ is increased. We show that two distinct phases of periodic solutions exist which exhibit manifestly different behavior. Response functions for these phases are shown to behave differently, joining at an apparent phase transition point.Comment: 17pages, 15 figure

A multilevel model for movement rehabilitation in Traumatic Brain Injury (TBI) using virtual environments

This paper presents a conceptual model for movement rehabilitation of traumatic brain injury (TBI) using virtual environments. This hybrid model integrates principles from ecological systems theory with recent advances in cognitive neuroscience, and supports a multilevel approach to both assessment and treatment. Performance outcomes at any stage of recovery are determined by the interplay of task, individual, and environmental/contextual factors. We argue that any system of rehabilitation should provide enough flexibility for task and context factors to be varied systematically, based on the current neuromotor and biomechanical capabilities of the performer or patient. Thus, in order to understand how treatment modalities are to be designed and implemented, there is a need to understand the function of brain systems that support learning at a given stage of recovery, and the inherent plasticity of the system. We know that virtual reality (VR) systems allow training environments to be presented in a highly automated, reliable, and scalable way. Presentation of these virtual environments (VEs) should permit movement analysis at three fundamental levels of behaviour: (i) neurocognitive bases of performance (we focus in particular on the development and use of internal models for action which support adaptive, on-line control); (ii) movement forms and patterns that describe the patients&#039; movement signature at a given stage of recovery (i.e, kinetic and kinematic markers of movement proficiency), (iii) functional outcomes of the movement. Each level of analysis can also map quite seamlessly to different modes of treatment. At the neurocognitive level, for example, semi-immersive VEs can help retrain internal modeling processes by reinforcing the patients&#039; sense of multimodal space (via augmented feedback), their position within it, and the ability to predict and control actions flexibly (via movement simulation and imagery training). More specifically, we derive four - key therapeutic environment concepts (or Elements) presented using VR technologies: Embodiment (simulation and imagery), Spatial Sense (augmenting position sense), Procedural (automaticity and dual-task control), and Participatory (self-initiated action). The use of tangible media/objects, force transduction, and vision-based tracking systems for the augmentation of gestures and physical presence will be discussed in this context

Vaccination against COVID-19 reduced the mortality risk of COVID-positive hip fracture patients to baseline levels:the nationwide data-linked IMPACT Protect study

SummaryThis nationwide study used data-linked records to assess the effect of COVID-19 vaccination among hip fracture patients. Vaccination was associated with a lower risk of contracting COVID-19 and, among COVID-positive patients, it reduced the mortality risk to that of COVID-negative patients. This provides essential data for future communicable disease outbreaks.PurposeCOVID-19 confers a three-fold increased mortality risk among hip fracture patients. The aims were to investigate whether vaccination was associated with: i) lower mortality risk, and ii) lower likelihood of contracting COVID-19 within 30 days of fracture.MethodsThis nationwide cohort study included all patients aged &gt; 50 years that sustained a hip fracture in Scotland between 01/03/20–31/12/21. Data from the Scottish Hip Fracture Audit were collected and included: demographics, injury and management variables, discharge destination, and 30-day mortality status. These variables were linked to government-managed population level records of COVID-19 vaccination and laboratory testing.ResultsThere were 13,345 patients with a median age of 82.0 years (IQR 74.0–88.0), and 9329/13345 (69.9%) were female. Of 3022/13345 (22.6%) patients diagnosed with COVID-19, 606/13345 (4.5%) were COVID-positive within 30 days of fracture. Multivariable logistic regression demonstrated that vaccinated patients were less likely to be COVID-positive (odds ratio (OR) 0.41, 95% confidence interval (CI) 0.34–0.48, p &lt; 0.001) than unvaccinated patients. 30-day mortality rate was higher for COVID-positive than COVID-negative patients (15.8% vs 7.9%, p &lt; 0.001). Controlling for confounders (age, sex, comorbidity, deprivation, pre-fracture residence), unvaccinated patients with COVID-19 had a greater mortality risk than COVID-negative patients (OR 2.77, CI 2.12–3.62, p &lt; 0.001), but vaccinated COVID19-positive patients were not at increased risk of death (OR 0.93, CI 0.53–1.60, p = 0.783).ConclusionVaccination was associated with lower COVID-19 infection risk. Vaccinated COVID-positive patients had a similar mortality risk to COVID-negative patients, suggesting a reduced severity of infection. This study demonstrates the efficacy of vaccination in this vulnerable patient group, and presents data that will be valid in the management of future outbreaks