Nonminimally coupled topological-defect boson stars: Static solutions

We consider spherically symmetric static composite structures consisting of a boson star and a global monopole, minimally or non-minimally coupled to the general relativistic gravitational field. In the non-minimally coupled case, Marunovic and Murkovic have shown that these objects, so-called boson D-stars, can be sufficiently gravitationally compact so as to potentially mimic black holes. Here, we present the results of an extensive numerical parameter space survey which reveals additional new and unexpected phenomenology in the model. In particular, focusing on families of boson D-stars which are parameterized by the central amplitude of the boson field, we find configurations for both the minimally and non-minimally coupled cases that contain one or more shells of bosonic matter located far from the origin. In parameter space, each shell spontaneously appears as one tunes through some critical central amplitude of the boson field. In some cases the shells apparently materialize at spatial infinity: in these instances their areal radii are observed to obey a universal scaling law in the vicinity of the critical amplitude. We derive this law from the equations of motion and the asymptotic behavior of the fields.Comment: 17 pages, 24 figure

Introduction to the symposium: Ivan Vladislavić, writing visual culture, and the globalization of a South African “artworld”

The introduction to this symposium considers South African author and editor Ivan Vladislavić’s engagement with South African visual culture and the significance of this to his emergence as a “world writer”. The symposium opens with an article by Sean O’Toole, which provides a comprehensive biographical context for Vladislavić’s engagement with art and proposes that his oeuvre be understood as a unique form of “creative criticism”. In their articles, Sue Marais and Jane Poyner offer close readings that draw out the critical role played by the visual cultures of the rarefied art world and everyday life, respectively, in two key texts where this creative criticism is in evidence: “Curiouser” from The Exploded View (2004) and Portrait with Keys (2006). James Graham’s article examines the nature and outcomes of Vladislavić’s work with other writers and visual artists as an editor, providing a theoretical framework that connects the biographical and formal concerns of the other articles by illustrating the cooperative ethos that undergirds Vladislavić’s critical and creative engagement with visual culture. The symposium therefore illustrates Vladislavić’s critical role in the negotiation of globalized artistic and literary fields, and in the constellation of a South African “artworld”

Landmine detection using semi-supervised learning.

Landmine detection is imperative for the preservation of both military and civilian lives. While landmines are easy to place, they are relatively difficult to remove. The classic method of detecting landmines was by using metal-detectors. However, many present-day landmines are composed of little to no metal, necessitating the use of additional technologies. One of the most successful and widely employed technologies is Ground Penetrating Radar (GPR). In order to maximize efficiency of GPR-based landmine detection and minimize wasted effort caused by false alarms, intelligent detection methods such as machine learning are used. Many sophisticated algorithms are developed and employed to accomplish this. One such successful algorithm is K Nearest Neighbors (KNN) classification. Most of these algorithms, including KNN, are based on supervised learning, which requires labeling of known data. This process can be tedious. Semi-supervised learning leverages both labeled and unlabeled data in the training process, alleviating over-dependency on labeling. Semi-supervised learning has several advantages over supervised learning. For example, it applies well to large datasets because it uses the topology of unlabeled data to classify test data. Also, by allowing unlabeled data to influence classification, one set of training data can be adopted into varying test environments. In this thesis, we explore a graph-based learning method known as Label Propagation as an alternative classifier to KNN classification, and validate its use on vehicle-mounted and handheld GPR systems

An intergroup analysis investigating the effects of holding a side handrail support on oxygen uptake values during the completion of the Chester Step Test

This dissertation investigates what effects a side handrail support has on oxygen uptake during the completion of the Chester Step Test (CST) in younger healthy individuals, older healthy individuals and in cardiac patients who are participating in a cardiac rehabilitation programme. This study was an intergroup analysis project which collaborated with two other University of Chester MSc research projects. Fifteen young healthy participants (5 males, 10 females), ten older healthy participants (3 males, 7 females) and seven cardiac patients (7 males, 0 females) were recruited for this study. The study followed a repeated measures design. The younger healthy participants completed three test protocols; performing the CST hands free, holding onto a side handrail with one hand and holding onto a side handrail with two hands. Due to time limitations, the older healthy participants and cardiac patients completed two CSTs; hands free and holding onto a side handrail with one hand. Oxygen uptake ( O2), heart rate (HR), metabolic equivalents (METs) and ratings of perceived exertion (RPE) were recorded at each stage of the CST. The exercise test was terminated if the participant: managed to complete all five stages of the CST, appeared to be stressed and indicated that they wanted to stop, reached their target heart rate point of 80% HR maximum or recorded an RPE value ≥ 15. Results: In all three testing groups, handrail support was found to have no statistically significant effects (p < 0.05) on O2 values at each stage of the CST. Handrail support was also found to have no statistically significent effects (p < 0.05) on MET, HR and RPE values in the three testing groups at each stage of the CST. The majority of participants found that handrail support made the test feel easier with 93% of the healthy young individuals, 57% of the older healthy participant group, and 86% of the cardiac patients stating that they preferred the test when handrail holding was allowed in comparison to hands free. Conclusion: In accordance with the findings by Barnett (2010), the current study found that handrail support had no statistically significant effect on oxygen uptake values when individuals performed the CST. Results from the current study provide encouraging support for the use of a side handrail support during the CST when testing both healthy individuals and cardiac patients in a cardiac rehabilitation setting

Synthesis and Reactions of Bridged Bicyclic Compounds

The research described in this thesis is devoted to synthetic and mechanistic studies in bridged bicyclic systems. The thesis is divided into three parts:- Part I: The Total Synthesis of Racemic Guaiol. The plant sesquiterpene guaiol has been synthesised in racemic form, from laevulinic acid and 2-methylcyclopentanon'e via an intermediate, l-methyltricyclo-(6,2,1,0 2,6)-undec-2 6-en-5,11-dione. Bridge fission of this diketone yields a hydroazulene enone-ester which has been elaborated to guaiol. Part II: The Acid Catalysed Cleavage of Bicyclo-(3,2,1)-oct-2-en-8-one. Although bicyclo-(3,2,1)-oct-2-en-8-one derivatives cleave in acidic solution to cycloheptene carboxylic acid derivatives, the corresponding alcohols do not fragment under similar circumstances. The corresponding syn alcohol undergoes a facile transannular cyclisation when treated with bromine. A similar transannular cyclisation occurs when the ketone is treated with bromine in an alcoholic solvent. Part III: A Re-investigation of the Reduction and Hydrolysis of Unsaturated Medium Ring Gem-Diesters. The previously reported base-catalysed transannular cyclisation of unsaturated medium ring gem-diesters has been re-investigated. In contrast to these earlier findings, the hydrolysis and reduction of these diesters proceed in the normal manner

Dynamical preparation of EPR entanglement in two-well Bose-Einstein condensates

We propose to generate Einstein-Podolsky-Rosen (EPR) entanglement between groups of atoms in a two-well Bose-Einstein condensate using a dynamical process similar to that employed in quantum optics. The local nonlinear S-wave scattering interaction has the effect of creating a spin squeezing at each well, while the tunneling, analogous to a beam splitter in optics, introduces an interference between these fields that results in an inter-well entanglement. We consider two internal modes at each well, so that the entanglement can be detected by measuring a reduction in the variances of the sums of local Schwinger spin observables. As is typical of continuous variable (CV) entanglement, the entanglement is predicted to increase with atom number, and becomes sufficiently strong at higher numbers of atoms that the EPR paradox and steering non-locality can be realized. The entanglement is predicted using an analytical approach and, for larger atom numbers, stochastic simulations based on truncated Wigner function. We find generally that strong tunnelling is favourable, and that entanglement persists and is even enhanced in the presence of realistic nonlinear losses.Comment: 15 pages, 19 figure

Coparenting in relation to children\u27s psychosocial and diabetes-specific adjustment

Objective: To explore the potential utility of a general and diabetes-specific measure of coparenting by evaluating linkages between coparenting and both the psychosocial and medical adjustment of children with type 1 diabetes (TID). Method: Mothers and fathers of children (ages 8-12 years; n=61) with TID completed questionnaires including measures of general and diabetes-specific coparenting, and children\u27s internalizing and externalizing problems. Medical adjustment included parent-reported diabetes management behaviors, children\u27s self-reported diabetes quality of life (QOL), and metabolic control (HbA1c) assessed during clinic appointments. Results: Coparenting conflict around general child rearing tasks was significantly related to children\u27s internalizing and externalizing problems. Diabetes-specific coparenting conflict was linked to poorer diabetes management behaviors and children\u27s reports of poorer diabetes-specific quality of life, but not HbA1c. Conclusions: Significant findings offer preliminary support for the inclusion of coparenting assessments among children with TID and warrant further exploration. © The Author 2009

A preliminary examination of the psychometric properties of the coparenting questionnaire and the diabetes-specific coparenting questionnaire in families of children with type I diabetes

Objectives: To examine the structure and psychometric properties of a general childrearing [Coparenting Questionnaire (CQ)] and an adapted Diabetes-Specific Coparenting Questionnaire (DCQ) and compare general and diabetes-specific coparenting among two-parent families caring for a child with type I diabetes. Methods: Mothers and fathers of children (N=61) aged 8-12 years with type I diabetes completed self-report measures of marital functioning, parenting, and coparenting, including the CQ and DCQ. Results: Confirmatory factor analyses favored the hypothesized 3-factor model for mothers and fathers for the CQ and DCQ. The internal consistencies and convergent validities of the CQ and DCQ were adequate. Coparenting conflict and triangulation were significantly higher for general child management than diabetes-specific issues. Conclusions: The CQ and DCQ represent two assessments that differentiate couples\u27 cooperation, conflict, and triangulation coparenting behaviors for general and diabetes-specific issues, and may potentially help inform family-based interventions. © The Author 2009

Erratum: Correction to: Predicting Dropout from Children\u27s Mental Health Services: Using a Need-Based Defnition of Dropout (Child psychiatry and human development (2020) 51 1 (13-26))

The original version of this article was unfortunately published with an error in Table 2. The confidence intervals listed in Table 2 were published incorrectly. The correct version of confidence intervals in Table 2 should read as below