Structure-Property Correlations in doped Bismuth Ferrite Ceramics

A detailed powder neutron diffraction study coupled with a complementary characterisation of the ferroelectricity and ferromagnetism, concerning two different compositions based on a parent BiFeO3 crystal lattice. The addition of Dy3+ into BiFeO3 ceramics shows how the parent polar R3c symmetry destabilises due to strain, linking to a large size variance between the two A-site cations (Dy3+ and Bi3+). This results in a loss of symmetry to polar Cc followed by a broad competitive phase system between strained Cc and non-polar Pnma symmetries. Increasingly strain on the lattice is seen until x=0.12 at which point the Pnma phase becomes dominant. However, phase co-existence persists until beyond x=0.25. Preliminary magnetisation measurements indicate a developing ferromagnetic character which increases in magnitude with Dy3+ content; electrical measurements suggest that whilst initial compositions of Bi0.95Dy0.05FeO3 show signs of polarity, more Dy3+ rich materials such as Bi0.70Dy0.30FeO3 shows relaxor like characteristics. This study also examines the addition of Alkali Metal Niobates to BiFeO3, looking at the Bi1-xKxFe1-xNbxO3 solid solution. Despite much individual attention on both BiFeO3 and KNbO3 a solid solution between the two has received less interest. Reported in this work is a detailed neutron and synchrotron X-ray powder diffraction study which demonstrates a polar R3c ? polar P4mm ? polar Amm2 series of structural phase transitions similar to that exhibited by PbZrO3–PbTiO3. Early electrical measurements show a non-ohmic electrode effects, making it difficult to determine the polar nature of the P4mm phase. Preliminary magnetic data suggests that the G-type anti-ferromagnetic spin cycloid may be retained, but some canting may occur, however the exact nature of the magnetic structure is unconfirmed, and evidence may initially suggest paramagnetism, canted antiferromagnetism or a spin glass like structure. All materials seem to exhibit a similar magnetic transition consistent with the parent lattice

Ontogenesis of the cornea and ciliary body : a morphological and molecular study

Includes bibliographical references.The anterior segment of the eye includes the cornea, lens, iris, ciliary body and trabecular meshwork, with each of these elements playing a vital role in the maintenance of vision. The primary objective of this research is to contribute towards the understanding of how specific genes control tissue specification and structural morphogenesis of the developing anterior segment of the eye. Despite its extensive use as a model organIsm, very little is known about the structure and development of the ciliary body in the mouse eye. Using scanning electron microscopy (SEM) the ciliary processes in the adult mouse were shown to form an irregular pattern, crossing over and interweaving, rather than lying parallel to one another, as observed in other mammals. Histological and SEM studies from E14.5 to P7 revealed that the first morphological sign of differentiation in the ciliary body is the appearance of an annular bulge around the optic cup margin; this is then gradually moulded to form discrete ciliary processes. A striking similarity between the developing capillary network and the adult ciliary folds was observed and suggests that the patterning template for the ciliary processes could be the underlying capillary network. Cell proliferation measurements and cell height assessments indicated that one of the first events occurring during the morphogenesis of ciliary processes is a proliferative surge occurring at about PO in the outer ciliary epithelium. It is likely that this surge together with increasing cell heights leads to a bulging of this layer. After a slight delay, the inner ciliary epithelium responds by proliferating and extending inwards towards the lens. Final shaping of the ciliary processes is achieved through cell height reductions in the inner ciliary epithelium. Gene expression analyses revealed dynamic changes in Bmp4 and LEF] expression patterns over the period of ciliary folding, while TgffJ1i4 expression in the ciliary body did not change during morphogenesis. These differences suggest that these genes play different roles in directing the specification and morphogenesis of the ciliary body. The temporal correlation between mitotic and cell height changes during ciliary body morphogenesis suggests that these processes play an integral role in the shaping of ciliary processes

An empirical analysis of macroeconomic factors and the effects on insurance demand and profitability

Thesis (M.M. (Finance & Investment))--University of the Witwatersrand, Faculty of Commerce, Law and Management, Graduate School of Business Administration, 2015.In any business it is critical to understand the key drivers of sales, costs and sustainability. This study aimed to understand whether macroeconomic indicators could be used to explain and predict insurance sales, cancellations and overall underwriting profitability in South Africa, and whether the drivers for insurance demand and profitability differed based on individual wealth. The significance of answering these questions is directly related to managing and running an insurance business in terms of which products to sell, and which consumer segments to target based on prevailing macroeconomic conditions. Regression analyses using Ordinary Least Squares were completed on both low income and high income consumer groups. Predictive models for sales (low income and high income groups) and profitability (low income group) were derived; however no model sufficiently explained cancellations in either income group. The explanatory variables for sales in the low and high income groups differed, suggesting that macroeconomic factors differentially influence buying behaviours in these groups. Sales and profitability in the low income group were explained by the same macroeconomic factors

Novel design for noise controlled semiconductor optical amplifier

The use of semiconductor optical amplifiers (SOA) in optical communications networks has so far been limited due to their inherent large noise figure (NF) compared to Erbium Doped Fibre Amplifiers. Therefore improvement of the noise performance of SOAs is critical to their widespread adoption in future networks. We propose to reduce the NF of the SOA by introducing a lasing cavity lateral to the axis of amplification of the device. The carrier density within the cavity is clamped at the lasing threshold. It is thus possible to engineer the carrier density distribution along the active waveguide by controlling the cavity design. According to our simulations, some of the cavity designs lead to a reduction of the noise figure in this novel SOA

Predation by Eurasian otters on adult Atlantic salmon

The return of the Eurasian otter to western Norway has sparked human-predator conflicts as otters prey on vulnerable Atlantic salmon populations. Although predation may not be the direct cause of salmon population declines, otters that kill salmon in rivers before they spawn may impact the salmon spawning stock, with potential consequences for stock recruitment. Concerns of local people and stakeholders suggest that otter predation inhibits recovery of salmon populations. However, there is limited information on mortality caused by otter predation on adult salmon. To gain insight into impacts of otter predation on salmon populations, I quantified the predation by otters on adult salmon in two rivers in Western Norway using a novel combination of radiotelemetry and temperature loggers. I tagged 45 salmon in Aureelva and 30 salmon in Søre Vartdalselva and tracked the salmon until they died or left the river. This method identified the fates of 95 % of tagged salmon. Otters killed 9 tagged salmon in Aureelva and 20 tagged salmon in Søre Vartdalselva. I found no evidence that otters selectively killed salmon based on sex, length, health status or activity level, which suggests that predation mortality on pre-spawners was additive. Otter predation contributed in reducing both salmon populations below their spawning targets, and without otter predation both populations would have been closer to reaching their spawning targets. However, the magnitude of predation differed greatly between rivers. Salmon in Søre Vartdalselva had greater predation risk compared to salmon in Aureelva, possibly due to differences in the number of holding pools between the two rivers. The findings from this study emphasise that management decisions should be guided by river-specific evaluations of impacts of otter predation on salmon, for which the combination of radiotelemetry and temperature loggers can provide a valuable tool.Predation by Eurasian otters on adult Atlantic salmonpublishedVersio

The Health of People with Intellectual Disability

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Ethical ecosurveillance: Mitigating the potential impacts on humans of widespread environmental monitoring

Ecosurveillance has proliferated in recent years, generating vast amounts of data on the natural environment. Ecosurveillance also has significant potential impacts on humans; therefore, researchers and policymakers need new conceptual tools to anticipate and mitigate any negative effects. Surveillance studies is an interdisciplinary field in the social sciences, providing a number of insights and practical lessons for predicting and managing the complex impacts (positive and negative, intended and unintended) of surveillance tools and practices. We draw on surveillance studies literature to propose two tools to guide designers and practitioners of ecosurveillance—a ‘red flag checklist’ to anticipate potential problems, and a ‘considerations guide’ to inform design decisions across a wide range of ecosurveillance systems. These tools will help ensure that the coming era of ecosurveillance is guided by responsible and ethical practices towards wildlife and humans alike, while also realizing the potential of these technologies for improving environmental outcomes.publishedVersio

State of the interface between conservation and physiology: A bibliometric analysis

Contemporary conservation science benefits from the perspectives of a variety of different disciplines, including a recent synergy with physiology, an interface known as 'conservation physiology'. To evaluate the degree of interaction between conservation and animal/plant physiology, we conducted three bibliometric analyses. We first pursued the use of the term 'conservation physiology' since its first definition in 2006 to determine how frequently it has been used and in which publications. Secondly, we evaluated the occurrence of conservation terms in animal and plant physiology journals, physiological terms in conservation journals, and a combination of terms in ecology journals. Thirdly, we explored trends in a subset of conservation physiology articles published between 2006 and 2012. We identified a surge in the use of the term 'conservation physiology' in 2012, after only a slow increase in usage between 2006 and 2011. Conservation journals tend to have been significantly more active in publishing conservation physiology than animal physiology, plant physiology or ecology journals. However, we found evidence that ecology and animal physiology journals began to incorporate more conservation physiology after 2006, while conservation- and plant physiology-themed journals did not. Among 299 conservation physiology articles that we identified, vertebrate taxa have been over-represented in conservation physiology compared with their relative taxonomic abundance, invertebrate taxa have been under-represented, and plants have been represented in proportion to their relative taxonomic abundance; however, those findings are reasonably consistent with publication trends in conservation biology. Diffuse distribution of conservation physiology papers throughout the literature may have been a barrier to the growth of the subdiscipline when the interface was emerging. The introduction of the focused journal Conservation Physiology in 2013 may address that deficiency. Moreover, development of a unifying framework could help to aggregate knowledge and attract potential contributors by highlighting and facilitating access to and application of conservation physiology

Inflammation and immunity in schizophrenia: implications for pathophysiology and treatment.

Complex interactions between the immune system and the brain might have important aetiological and therapeutic implications for neuropsychiatric brain disorders. A possible association between schizophrenia and the immune system was postulated over a century ago, and is supported by epidemiological and genetic studies pointing to links with infection and inflammation. Contrary to the traditional view that the brain is an immunologically privileged site shielded behind the blood-brain barrier, studies in the past 20 years have noted complex interactions between the immune system, systemic inflammation, and the brain, which can lead to changes in mood, cognition, and behaviour. In this Review, we describe some of the important areas of research regarding innate and adaptive immune response in schizophrenia and related psychotic disorders that, we think, will be of interest to psychiatric clinicians and researchers. We discuss potential mechanisms and therapeutic implications of these findings, including studies of anti-inflammatory drugs in schizophrenia, describe areas for development, and offer testable hypotheses for future investigations.The work was supported by a doctoral clinical research training fellowship grant from the Wellcome Trust to Golam Khandaker (094790/Z/10/Z; 2010-‘13), grants from the Stanley Medical Research Institute and the National Institutes of Mental Health (grant# MH-94268) to Robert Yolken, and grants from the Wellcome Trust (095844/Z/11/Z & 088869/Z/09/Z), and the NIHR (RP-PG-0606-1335) to Peter Jones.This is the accepted manuscript. The final version is available from Elsevier at http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366%2814%2900122-9/abstrac