Contrast integration over area is extensive: a three-stage model of spatial summation

Classical studies of area summation measure contrast detection thresholds as a function of grating diameter. Unfortunately, (i) this approach is compromised by retinal inhomogeneity and (ii) it potentially confounds summation of signal with summation of internal noise. The Swiss cheese stimulus of T. S. Meese and R. J. Summers (2007) and the closely related Battenberg stimulus of T. S. Meese (2010) were designed to avoid these problems by keeping target diameter constant and modulating interdigitated checks of first-order carrier contrast within the stimulus region. This approach has revealed a contrast integration process with greater potency than the classical model of spatial probability summation. Here, we used Swiss cheese stimuli to investigate the spatial limits of contrast integration over a range of carrier frequencies (1–16 c/deg) and raised plaid modulator frequencies (0.25–32 cycles/check). Subthreshold summation for interdigitated carrier pairs remained strong (~4 to 6 dB) up to 4 to 8 cycles/check. Our computational analysis of these results implied linear signal combination (following square-law transduction) over either (i) 12 carrier cycles or more or (ii) 1.27 deg or more. Our model has three stages of summation: short-range summation within linear receptive fields, medium-range integration to compute contrast energy for multiple patches of the image, and long-range pooling of the contrast integrators by probability summation. Our analysis legitimizes the inclusion of widespread integration of signal (and noise) within hierarchical image processing models. It also confirms the individual differences in the spatial extent of integration that emerge from our approach.

Watermarking biomedical time series data

This thesis addresses the problem of information hiding in low dimensional digital data focussing on issues of privacy and security in Electronic Patient Health Records (EPHRs). The thesis proposes a new security protocol based on data hiding techniques for EPHRs. This thesis contends that embedding of sensitive patient information inside the EPHR is the most appropriate solution currently available to resolve the issues of security in EPHRs. Watermarking techniques are applied to one-dimensional time series data such as the electroencephalogram (EEG) to show that they add a level of confidence (in terms of privacy and security) in an individual’s diverse bio-profile (the digital fingerprint of an individual’s medical history), ensure belief that the data being analysed does indeed belong to the correct person, and also that it is not being accessed by unauthorised personnel. Embedding information inside single channel biomedical time series data is more difficult than the standard application for images due to the reduced redundancy. A data hiding approach which has an in built capability to protect against illegal data snooping is developed. The capability of this secure method is enhanced by embedding not just a single message but multiple messages into an example one-dimensional EEG signal. Embedding multiple messages of similar characteristics, for example identities of clinicians accessing the medical record helps in creating a log of access while embedding multiple messages of dissimilar characteristics into an EPHR enhances confidence in the use of the EPHR. The novel method of embedding multiple messages of both similar and dissimilar characteristics into a single channel EEG demonstrated in this thesis shows how this embedding of data boosts the implementation and use of the EPHR securely.

Protein oxidative modifications:new mass spectrometry approaches to detection in biological samples

In inflammatory diseases, release of oxidants leads to oxidative damage to proteins. The precise nature of oxidative damage to individual proteins depends on the oxidant involved. Chlorination and nitration are markers of modification by the myeloperoxidase-H2O2-Cl- system and nitric oxide-derived oxidants, respectively. Although these modifications can be detected by western blotting, currently no reliable method exists to identify the specific sites damage to individual proteins in complex mixtures such as clinical samples. We are developing novel LCMS2 and precursor ion scanning methods to address this. LC-MS2 allows separation of peptides and detection of mass changes in oxidized residues on fragmentation of the peptides. We have identified indicative fragment ions for chlorotyrosine, nitrotyrosine, hydroxytyrosine and hydroxytryptophan. A nano-LC/MS3 method involving the dissociation of immonium ions to give specific fragments for the oxidized residues has been developed to overcome the problem of false positives from ions isobaric to these immonium ions that exist in unmodified peptides. The approach has proved able to identify precise protein modifications in individual proteins and mixtures of proteins. An alternative methodology involves multiple reaction monitoring for precursors and fragment ions are specific to oxidized and chlorinated proteins, and this has been tested with human serum albumin. Our ultimate aim is to apply this methodology to the detection of oxidative post-translational modifications in clinical samples for disease diagnosis, monitoring the outcomes of therapy, and improved understanding of disease biochemistry.

Dynamic spectrum access in heterogeneous unlicensed wireless networks

Existing wireless systems are normally regulated by a fixed spectrum assignment strategy. This policy leads to an undesirable situation that some systems may only use the allocated spectrum to a limited extent while others have very serious spectrum insufficiency situation. Dynamic Spectrum Access (DSA) is emerging as a promising technology to address this issue such that the unused licensed spectrum can be opportunistically accessed by the unlicensed users. To enable DSA, the unlicensed user shall have the capability of detecting the unoccupied spectrum, controlling its spectrum access in an adaptive manner, and coexisting with other unlicensed users automatically. In this article, we propose a radio system Transmission Opportunity-based spectrum access control protocol with the aim to improve spectrum access fairness and ensure safe coexistence of multiple heterogeneous unlicensed radio systems. In the scheme, multiple radio systems will coexist and dynamically use available free spectrum without interfering with licensed users. Simulation is carried out to evaluate the performance of the proposed scheme with respect to spectrum utilisation, fairness and scalability. Comparing with the existed studies, our strategy is able to achieve higher scalability and controllability without degrading spectrum utilisation and fairness performance.

Peer mentoring works!

This report draws on the findings of a three year study into peer mentoring conducted at 6 Higher Education Institutions (HEIs), 5 of which were in the UK, 1 of which was in Norway. Following a multiple case-study design, quantitative and qualitative research was conducted in collaboration with the project partners. The research findings provide empirical evidence that peer mentoring works! In particular the report provides: - An Executive Summary outlining the main project findings - A synopsis of the relevant literature – and a link to a much larger literature review undertaken at the beginning of the study - A working conceptual framework and set of research questions - An overview and rationale of the methodological approach and tools - Evidence of the value of peer mentoring in promoting a ‘smooth’ transition into university - Evidence that peer mentoring works by providing the means by which new students can access peer support in both social and academic spheres throughout their first year - Identification of the main challenges of peer mentoring - Evidence of the manner in which writing peer mentoring works by providing bespoke help for individual students - A discussion section in which a new approach to peer mentoring, Transition+, is proposed. The report concludes with recommendations for: Higher Education Institutions: Students: Policy Makers: and, Individuals within HEIs wishing to establish peer mentoring.

Understanding sustainable development

Sustainable development is notoriously difficult to grasp for students and professionals. Multidimensional, encompassing social, ecological and economic theories, policies and practice, it can be a maze of complexity and contradiction. This powerful new textbook, by a topic instructor in the field, is the first to unravel sustainable development and provide readers with the deep understanding so often missing in other texts. The book adopts a multi-perspective approach designed specifically to allow access to the topic from a wide range of educational and professional backgrounds and to develop understanding of a diversity of approaches and traditions at different levels. It features multiple entry points, explains jargon and explores controversies. Also offering boxed examples from the local to the global, Understanding Sustainable Development is the most complete guide to the subject for course leaders, students and self-learners.

Characterization of Transglutaminase 2 in macrophage clearance of apoptotic cells

Removal of dead or diseased cells is crucial feature of apoptosis for managing many biological processes such as tissue remodelling, tissue homeostasis and resolution and control of immune responses throughout life. Tissue transglutaminase (TG2) is a protein crosslinking enzyme that has been implicated in apoptotic cell clearance but also mediates many important cell functions including cell adhesion, migration and monocyte-macrophage differentiation. Cell surface-associated TG2 regulates cell adhesion and migration, via its association with receptors such as syndecan-4, ß1 and ß3 integrin. Whilst defective apoptotic cell clearance has been described in TG2-deficient mice, the precise extracellular role of TG2 in apoptotic cell clearance remains ill-defined. This thesis addresses macrophage TG2 in cell corpse clearance. TG2 expression (cytosolic and cell surface) in human macrophages was revealed and data demonstrate that loss of TG2 activity through the use of inhibitors of function, including cellimpermeable inhibitors significantly inhibit the ability of macrophages to clear apoptotic cells (AC). This includes reduced macrophage recruitment to and binding of apoptotic cells. Association studies reveal TG2-syndecan-4 interaction through heparan sulphate side chains, and knockdown of syndecan-4 reduces cell surface TG2 activity and apoptotic cell clearance. Furthermore, inhibition of TG2 activity reduces crosslinking of CD44, reported to augment AC clearance. Thus it defines for the first time a role for TG2 activity at the cell surface of human macrophages in multiple stages of AC clearance and proposed that TG2, in association with heparan sulphates, may exert its effect on AC clearance via crosslinking of CD44.

Can restricting calories help you to live longer?

Excess calorie consumption is associated with metabolic disorders and increased incidence of morbidity. Restricting calorie content, either by daily calorie restriction or intermittent fasting periods, has multiple benefits including weight loss and improved body composition. Previous research has shown that restricting calories in this way can increase longevity and slow the ageing process in laboratory animals, although only sparse data exist in human populations. This review critically evaluates the benefits of these dietary interventions on age-related decline and longevity.

Textbook on contract law

Jill Poole's immensely popular Textbook on Contract Law has been guiding students through contract law for many years. The accessible writing style and focus on key principles and developments in contract law make this text a favourite with students and lecturers alike. The author places the law of contract clearly within its wider context before proceeding to provide detailed yet accessible treatment of all the key areas encountered when studying contract law. Key features: · Key points, illustrative examples and questions encourage a deeper understanding of the central facts and issues · Each chapter begins with a summary of key issues, providing an overview of key themes and points of law, and concludes with suggestions for further reading, guiding you towards the most relevant texts and articles · An attractive page design highlights headings, case summaries, case extracts and a variety of learning features, making navigation through the text easy Fully supported by an Online Resource Centre, which provides: Student Resources Regular updates on new legislation, cases, and other important developments Guidance on answering questions in contract law Self-test questions and answers linked with Casebook on Contract Law Lecturer Resources A test bank of 300 multiple choice questions with answers and feedback

A safety evaluation of ranibizumab in the treatment of age-related macular degeneration

Introduction: The use of intravitreal ranibizumab has transformed the outcomes for thousands of patients with wet age related macular degeneration (AMD), which is the leading cause of blindness in developed countries. Prior to its introduction, most patients with wet AMD would rapidly lose central vision. The use of intravitreal ranibizumab has been shown to reduce certifiable visual loss by about a half. Current treatment regimens with ranibizumab in wet AMD require multiple injections over several years and so it is highly relevant to review the safety record of this important drug.Areas covered: This review considers the important ocular and systemic adverse events (AE) that have been reported in the literature, particularly in the context of the pivotal clinical trials that have been performed. It also reviews the safety of other anti-VEGF drugs that are used in wet AMD, namely bevacizumab and aflibercept, and compares these drugs with ranibizumab.Expert opinion: Overall, intravitreal ranibizumab can be considered a safe and highly effective drug for patients with wet AMD. However recent concerns about retinal thinning following ranibizumab therapy, possible systemic AE associated with all anti-VEGF drugs and the occurrence of complications relating to drug preparation and delivery must be considered. © 2014 Informa UK, Ltd.

Operational Rules for a Mixed Operator of the Erdélyi-Kober Type

2000 Mathematics Subject Classification: 26A33 (main), 44A40, 44A35, 33E30, 45J05, 45D05

Formal Specification of Relational Model of Data in Z-Notation

Владимир Димитров - Целта на настоящия доклад е формалната спецификация на релационния модел на данни. Тази спецификация след това може да бъде разширена към Обектно-релационния модел на данни и към Потоците от данни.

A longitudinal study of accommodative changes in biometry during incipient presbyopia

PURPOSE: To profile accommodative biometric changes longitudinally and to determine the influence of age-related ocular structural changes on the accommodative response prior to the onset of presbyopia. METHODS: Twenty participants (aged 34-41 years) were reviewed at six-monthly intervals over two and a half years. At each visit, ocular biometry was measured with the LenStar biometer (www.Haag-Streit.com) in response to 0.00, 3.00 and 4.50 D stimuli. Accommodative responses were measured by the WAM 5500 Auto Ref/Keratometer (www.grandseiko.com). RESULTS: During accommodation, anterior chamber depth reduced (F = 29, p < 0.001), whereas crystalline lens thickness (F = 39, p < 0.001) and axial length (F = 5.4, p = 0.009) increased. The accommodative response (F = 5.5, p = 0.001) and the change in anterior chamber depth (F = 3.1, p = 0.039), crystalline lens thickness (F = 3.0, p = 0.042) and axial length (F = 2.5, p = 0.038) in response to the 4.50 D accommodative target reduced after 2.5 years. However, the change in anterior chamber depth (F = 2.2, p = 0.097), crystalline lens thickness (F = 1.7, p = 0.18) and axial length (F = 1.0, p = 0.40) per dioptre of accommodation exerted remained invariant after 2.5 years. The increase in disaccommodated crystalline lens thickness with age was not significantly associated with the reduction in accommodative response (R = 0.32, p = 0.17). CONCLUSION: Despite significant age-related structural changes in disaccommodated biometry, the change in biometry per dioptre of accommodation exerted remained invariant with age. The present study supports the Helmholtz theory of accommodation and suggests an increase in lenticular stiffness is primarily responsible for the onset of presbyopia.

Three-port DC-DC converter for stand-alone photovoltaic systems

System efficiency and cost effectiveness are of critical importance for photovoltaic (PV) systems. This paper addresses the two issues by developing a novel three-port dc-dc converter for stand-alone PV systems, based on an improved Flyback-Forward topology. It provides a compact single-unit solution with a combined feature of optimized maximum power point tracking (MPPT), high step-up ratio, galvanic isolation, and multiple operating modes for domestic and aerospace applications. A theoretical analysis is conducted to analyze the operating modes followed by simulation and experimental work. This paper is focused on a comprehensive modulation strategy utilizing both PWM and phase-shifted control that satisfies the requirement of PV power systems to achieve MPPT and output voltage regulation. A 250-W converter was designed and prototyped to provide experimental verification in term of system integration and high conversion efficiency.

Are mangroves in the tropical Atlantic ripe for invasion? Exotic mangrove trees in the forests of South Florida

Abstract Two species of mangrove trees of Indo- Pacific origin have naturalized in tropical Atlantic mangrove forests in South Florida after they were planted and nurtured in botanic gardens. Two Bruguiera gymnorrhiza trees that were planted in the intertidal zone in 1940 have given rise to a population of at least 86 trees growing interspersed with native mangrove species Rhizophora mangle, Avicennia germinans and Laguncularia racemosa along 100 m of shoreline; the population is expanding at a rate of 5.6% year-1. Molecular genetic analyses confirm very low genetic diversity, as expected from a population founded by two individuals. The maximumnumber of alleles at any locus was three, and we measured reduced heterozygosity compared to native-range populations. Lumnitzera racemosa was introduced multiple times during the 1960s and 1970s, it has spread rapidly into a forest composed of native R. mangle, A. germinans, Laguncularia racemosa and Conocarpus erectus and now occupies 60,500 m2 of mangrove forest with stem densities of 24,735 ha-1. We estimate the population growth rate of Lumnitzera racemosa to be between 17 and 23% year-1. Populations of both species of naturalized mangroves are dominated by young individuals. Given the long life and water-dispersed nature of propagules of the two exotic species, it is likely that they have spread beyond our survey area. We argue that the species-depauperate nature of tropical Atlantic mangrove forests and close taxonomic relatives in the more species-rich Indo-Pacific region result in the susceptibility of tropical Atlantic mangrove forests to invasion by Indo-Pacific mangrove species.