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Search Results: 1 - 10 of 114 matches for " Callum Quigley "
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Mirror Symmetry in Physics: The Basics
Callum Quigley
Mathematics , 2014, DOI: 10.1007/978-1-4939-2830-9
Abstract: These notes are aimed at mathematicians working on topics related to mirror symmetry, but are unfamiliar with the physical origins of this subject. We explain the physical concepts that enable this surprising duality to exist, using the torus as an illustrative example. Then, we develop the basic foundations of conformal field theory so that we can explain how mirror symmetry was first discovered in that context. Along the way we will uncover a deep connection between conformal field theories with (2,2) supersymmetry and Calabi-Yau manifolds. (Based on lectures given during the "Thematic Program on Calabi-Yau Varieties: Arithmetic, Geometry and Physics" at the Fields Institute in Toronto, October 10-11, 2013.)
Linear Sigma Models with Torsion
Callum Quigley,Savdeep Sethi
Mathematics , 2011, DOI: 10.1007/JHEP11(2011)034
Abstract: Gauged linear sigma models with (0,2) supersymmetry allow a larger choice of couplings than models with (2,2) supersymmetry. We use this freedom to find a fully linear construction of torsional heterotic compactifications, including models with branes. As a non-compact example, we describe a family of metrics which correspond to deformations of the heterotic conifold by turning on H-flux. We then describe compact models which are gauge-invariant only at the quantum level. Our construction gives a generalization of symplectic reduction. The resulting spaces are non-Kahler analogues of familiar toric spaces like complex projective space. Perturbatively conformal models can be constructed by considering intersections.
Constraints on String Cosmology
Stephen R. Green,Emil J. Martinec,Callum Quigley,Savdeep Sethi
Physics , 2011, DOI: 10.1088/0264-9381/29/7/075006
Abstract: String theory contains sources like orientifold planes that support higher derivative interactions. These interactions make possible static flux compactifications which are forbidden in supergravity. They can also lead to violations of the strong energy condition (SEC) which is needed for an accelerating universe. We examine how large a violation is possible in the context of the heterotic string compactified to four dimensions. We find that de Sitter solutions are still not possible but that classically forbidden anti-de Sitter solutions are possible.
The Potential of Photo-Talks to Reveal the Development of Scientific Discourses  [PDF]
Cassie Quigley, Gayle Buck
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.32033
Abstract: This study explores the potential of a photo-elicitation technique, photo-talks (Serriere, 2010), for understanding how young girls understand, employ and translate new scientific discourses. Over the course of a nine week period, 24 kindergarten girls in an urban girls’ academy were observed, videotaped, photographed and interviewed while they were immersed into scientific discourse. This paper explicitly describes how their emerging discursive patterns were made visible through this methodological tool. The findings are presented in vignettes in three themes uncovered during our analysis which are the following: Presented the recollection of the scientific Discourse, Described the understanding of scientific Discourse, and Created an opportunity for the translation into everyday discourse. Science educators can benefit from this methodological tool as a reflective tool with their participants, to validate and/or complicate data. Additionally, this methodological tool serves to make discourse patterns more visible by providing a visual backdrop to the conversations thus revealing the development as it is occurring in young children.
Survival Model Inference Using Functions of Brownian Motion  [PDF]
John O’Quigley
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.36098
Abstract: A family of tests for the presence of regression effect under proportional and non-proportional hazards models is described. The non-proportional hazards model, although not completely general, is very broad and includes a large number of possibilities. In the absence of restrictions, the regression coefficient, β(t), can be any real function of time. When β(t) = β, we recover the proportional hazards model which can then be taken as a special case of a non-proportional hazards model. We study tests of the null hypothesis; H0:β(t) = 0 for all t against alternatives such as; H1:∫β(t)dF(t) ≠ 0 or H1:β(t) ≠ 0 for some t. In contrast to now classical approaches based on partial likelihood and martingale theory, the development here is based on Brownian motion, Donsker’s theorem and theorems from O’Quigley [1] and Xu and O’Quigley [2]. The usual partial likelihood score test arises as a special case. Large sample theory follows without special arguments, such as the martingale central limit theorem, and is relatively straightforward.
The Insulin-Like Growth Factor System and Nutritional Assessment
Callum Livingstone
Scientifica , 2012, DOI: 10.6064/2012/768731
The Insulin-Like Growth Factor System and Nutritional Assessment
Callum Livingstone
Scientifica , 2012, DOI: 10.6064/2012/768731
Abstract: Over recent years there has been considerable interest in the role of the insulin-like growth factor (IGF) system in health and disease. It has long been known to be dysregulated in states of under- and overnutrition, serum IGF-I levels falling in malnourished patients and responding promptly to nutritional support. More recently, other proteins in this system have been observed to be dysregulated in both malnutrition and obesity. Currently no biochemical marker is sufficiently specific for use in screening for malnutrition, but levels may be valuable in providing information on nutritional status and in monitoring of nutritional support. All have limitations as nutritional markers in that their serum levels are influenced by factors other than nutritional status, most importantly the acute phase response (APR). Levels should be interpreted along with clinical findings and the results of other investigations such as C-reactive protein (CRP). This paper reviews data supporting the use of proteins of the IGF system as nutritional markers. 1. Introduction The insulin-like growth factor (IGF) system consists of the peptide hormones IGF-I and -II, their cell surface receptors, and IGF-binding proteins (IGFBPs). IGF-I and -II are the principal components of the system. They have biological roles in mediating the effects of growth hormone (GH) and during development [1]. Their actions can be divided into rapid metabolic effects and longer-term growth-promoting effects [2]. Compared to insulin both circulate in relatively high concentrations in serum. They are also released into interstitial fluids where they act locally in a paracrine or autocrine manner. The IGFs generate their biological responses by activating a receptor tyrosine kinase (RTK) which initiates an intracellular signalling cascade [3]. Their function is modulated by the IGFBPs [4]. 1.1. The IGFs and Their Receptors IGF-I exerts acute anabolic actions on protein and carbohydrate metabolism by increasing the cellular uptake of amino acids. As such, it is an important regulator of muscle mass. It has long-term effects on cell proliferation, differentiation, and apoptosis [4, 5]. It is a potent mitogen increasing DNA synthesis and accelerating cell cycle progression. IGF-I is predominantly synthesised in liver, in response to GH, but is also synthesised to a lesser extent in various other tissues. Other factors which regulate its production include genetic factors, nutrition, and other hormones such as thyroxine, gonadal steroids, and cortisol. Its biological half-life in serum is only a few hours.
Chronic Kidney Disease: Highlights for the General Pediatrician
Raymond Quigley
International Journal of Pediatrics , 2012, DOI: 10.1155/2012/943904
Abstract: Chronic kidney disease in the pediatric population has been increasing. Early detection and treatment can slow down the progression of kidney disease and help prevent the development of end stage renal disease. In addition, as the kidney function declines, there are many pathophysiologic interactions with other organ systems that need to be monitored and treated. In particular, because of impaired vitamin D metabolism, calcium and phosphorus homeostasis is dysregulated and results in secondary bone disease. Anemia is common due to a number of factors including impaired erythropoietin production. Growth is often impacted by chronic kidney disease but can be improved by proper treatment. Complications of chronic kidney disease can be minimized by proper monitoring and treatment of these parameters. The general pediatrician plays a critical role in this process.
Welcome to Computers––A New Open Access Journal for Computer Science
Aaron Quigley
Computers , 2012, DOI: 10.3390/computers1010001
Abstract: For the past seven decades, computers have radically changed the world we live in. From machines for calculation, computers are now platforms for information processing and computation, supporting the entire spectrum of human endeavour. While computer science is a relatively young field, it is shaping how people live in our modern world. There is not an area of human society that has not been affected by computers and the power they afford us. Computer science touches on every facet of science, art, engineering and economics. Its impact ranges from electronic commerce to improved medical devices; and from enhanced communication to new forms of media and entertainment. The future, with ubiquitous computational power and natural user interfaces, will extend and enhance all human capabilities. To reach this future we need to quickly and freely disseminate our cutting edge research results globally, and this journal aims to help us achieve that. [...]
Changing face of irritable bowel syndrome
Quigley E
World Journal of Gastroenterology , 2006,
Abstract: Recent years have witnessed tremendous progress in our understanding of irritable bowel syndrome (IBS). It is evident that this is a truly global disease associated with significant symptoms and impairments in personal and social functioning for afflicted individuals. Advances in our understanding of gut flora-mucosal interactions, the enteric nervous system and the brain-gut axis have led to substantial progress in the pathogenesis of symptoms in IBS and have provided some hints towards the basic etiology of this disorder, in some subpopulations, at the very least. We look forward to a time when therapy will be addressed to pathophysiology and perhaps, even to primary etiology. In the meantime, a model based on a primary role for intestinal inflammation serves to integrate the various strands, which contribute to the presentation of IBS.
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