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Search Results: 1 - 10 of 120 matches for " Calum Spicer "
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Laplacians on Julia Sets III: Cubic Julia Sets and Formal Matings
Calum Spicer,Robert S. Strichartz,Emad Totari
Mathematics , 2012,
Abstract: We continue the study of constructing invariant Laplacians on Julia sets, and studying properties of their spectra. In this paper we focus on two types of examples: 1) Julia sets of cubic polynomials $z^3 + c$ with a single critical point; 2) formal matings of quadratic Julia sets. The general scheme introduced in earlier papers in this series involves realizing the Julia set as a circle with identifications, and attempting to obtain the Laplacian as a renormalized limit of graph Laplacians on graphs derived form the circle with identifications model. In the case of cubic Julia sets the details follows the pattern established for quadratic Julia sets, but for matings the details are quite challenging, and we have only been completely successful for one example. Once we have constructed the Laplacian, we are able to use numerical methods to approximate the eigenvalues and eigenfunctions. One striking observation from the data is that for the cubic Julia sets the multiplicities of all eigenspaces (except for the trivial eigenspace of constants) are even numbers. Nothing like this is valid for the quadratic julia sets studied earlier. We are able to explain this, based on the fact that three is an odd number, and more precisely because the dihedral-3 symmetry group has only two distinct one-dimensional irreducible representations.
Institutional policy learning and formal federal-urban engagement in Canada
Zachary Spicer
Commonwealth Journal of Local Governance , 2010, DOI: 10.5130/cjlg.v0i7.1892
Abstract: Canada has experienced two formal federal ministries dedicated to addressing urban issues. The first, the Ministry of State for Urban Affairs, encountered resistance from provincial governments and its fellow departments. Both worked to undermine it. The second, the Ministry of State for Infrastructure and Communities, was created with a more conciliatory tone towards the provincial governments and its ministerial colleagues. This paper examines the establishment of both ministries and tracks their efforts using a policy learning and lesson-drawing framework, concluding that common institutional actors, such as the Privy Council, were responsible for the Ministry of State for Infrastructure and Communities’ change in tone and approach to multilevel governance. General lessons are drawn about inter-governmental relations and multi-level policy formation in federal systems.
What Are the bona fide GSK3 Substrates?
Calum Sutherland
International Journal of Alzheimer's Disease , 2011, DOI: 10.4061/2011/505607
Abstract: Nearly 100 proteins are proposed to be substrates for GSK3, suggesting that this enzyme is a fundamental regulator of almost every process in the cell, in every tissue in the body. However, it is not certain how many of these proposed substrates are regulated by GSK3 in vivo. Clearly, the identification of the physiological functions of GSK3 will be greatly aided by the identification of its bona fide substrates, and the development of GSK3 as a therapeutic target will be highly influenced by this range of actions, hence the need to accurately establish true GSK3 substrates in cells. In this paper the evidence that proposed GSK3 substrates are likely to be physiological targets is assessed, highlighting the key cellular processes that could be modulated by GSK3 activity and inhibition. 1. Introduction 1.1. Why Identify Substrates? Glycogen synthase kinase-3 (GSK3) was first reported as a glycogen synthase phosphorylating activity in rabbit skeletal muscle (the third to be found, hence GSK3) [1]. GSK3 was later identified as a major tau protein kinase [2]. These substrates immediately focused attention on the importance of GSK3 in glucose metabolism and neurodegeneration, and these remain major areas of GSK3 research. Indeed GSK3 inhibitors, which were initially developed for the treatment of diabetes, are now being investigated for the treatment of Alzheimer’s disease, as well as many other conditions [3–5]. These therapeutic programmes have arisen directly from substrate identification; however, more recently the multitude of GSK3 substrates proposed in the literature has lessened therapeutic interest in this enzyme. It is therefore of great importance to establish beyond doubt what the physiological targets of this enzyme are, not only to focus therapeutic potential but also establish actual side effects of manipulating GSK3 activity. 1.2. Problems with False Positives It is reasonably straightforward to implicate a protein as a substrate for a kinase, with evidence ranging from the existence of a consensus phosphorylation sequence in the primary structure of a protein through to regulation of phosphorylation by manipulation of the protein kinase in vivo. Unfortunately, the existence of a consensus sequence is rarely a good predictor of whether a protein will be a substrate of that kinase. Indeed GSK3 target consensus sequences occur in more than half of all known human proteins, most of which are clearly not regulated by GSK3. In addition, phosphorylation in vitro does not always correlate with phosphorylation in vivo, and great care has to be taken
Women's Offences and Biblical Law
Calum Carmichael
Forum Historiae Iuris , 1998,
Abstract:
Tech Expo: A Model for Emerging Technology Education for Library Staff
Lisa Johnston,Scott Spicer
Journal of Library Innovation , 2012,
Abstract: Emerging technologies, such as personal information management tools like Zotero, productivity software like Google Documents, and Web-based API's and mashups are important resources for library staff development and productivity. To keep up with rapid technological change, the University of Minnesota Libraries developed a staff education program on emerging technologies. Begun in 2009, the fun and interactive program called Tech Expo has been a success. This paper describes the approach taken and lessons learned.
A Novel Solid State Non-Dispersive Infrared CO2 Gas Sensor Compatible with Wireless and Portable Deployment
Desmond Gibson,Calum MacGregor
Sensors , 2013, DOI: 10.3390/s130607079
Abstract: This paper describes development of a novel mid-infrared light emitting diode (LED) and photodiode (PD) light source/detector combination and use within a non-dispersive infrared (NDIR) carbon dioxide gas sensor. The LED/PD based NDIR sensor provides fast stabilisation time (time required to turn on the sensor from cold, warm up, take and report a measurement, and power down again ≈1 second), longevity (>15 years), low power consumption and low cost. Described performance is compatible with “fit and forget” wireless deployed sensors in applications such as indoor air quality monitoring/control & energy conservation in buildings, transport systems, horticultural greenhouses and portable deployment for safety, industrial and medical applications. Fast stabilisation time, low intrinsic power consumption and cycled operation offer typical energy consumption per measurement of mJ’s, providing extended operation using battery and/or energy harvesting strategies (measurement interval of ≈ 2 minutes provides >10 years operation from one AA battery). Specific performance data is provided in relation to measurement accuracy and noise, temperature performance, cross sensitivity, measurement range (two pathlength variants are described covering ambient through to 100% gas concentration), comparison with NDIR utilizing thermal source/pyroelectric light source/detector combination and compatibility with energy harvesting. Semiconductor based LED/PD processing together with injection moulded reflective optics and simple assembly provide a route to low cost high volume manufacturing.
Revising our Curriculum/Empowering Students: Teachers‘ Preparation and Perceptions about Bilingual Writing
Maria Luisa Spicer-Escalante
Theory and Practice in Language Studies , 2011, DOI: 10.4304/tpls.1.11.1453-1458
Abstract: While emphasis on writing instruction has been a main concern in teaching Spanish to bilingual students in the U. S., it is an area in which very few theoretical advances have been made; in Mexico’s case the situation is even more challenging. Therefore, based on classroom observations, and individual interviews with both teachers and students, and on the collection of class syllabi, this paper seeks to describe the current state of affairs regarding Spanish and English writing instruction for bilingual students in both countries. The main objectives are: 1) the analysis and comparison of the diverse teaching methodologies that high school teachers use to teach Spanish and English writing; 2) the analysis of the effects that the specific observed writing instruction has on students’ perceptions about their own writing in both languages; and 3) the analysis of the perceptions that teachers have about their students’ writing.
A STUDY OF THE COGNITIVE PROCESSING MODELS USED IN THE APPRAISAL SYSTEM: THE MALAYSIAN PUBLIC SERVICE
Rusli Ahmad,David P. Spicer
Asian Academy of Management Journal , 2002,
Abstract: The purpose of the paper is to present the results of semi-structured interviews undertaken with expert raters (School Principals) within the Malaysian Education System. These interviews have been conducted using a cognitive mapping protocol. The resultant causal cognitive maps are explored for what they have to tell us about the Cognitive Processing Models (CPM) applied in appraisal decision-making. From the research findings, it is clear that raters recognized the CPM steps in their performance appraisal (PA) practice. The study also identifies the differences between individual expert raters in terms of concepts and complexity in the decision making process. Finally, the study discusses the implications of the research for the CPM and appraisal decision-making process.
Propagule Pressure and Climate Contribute to the Displacement of Linepithema humile by Pachycondyla chinensis
Eleanor Spicer Rice, Jules Silverman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0056281
Abstract: Identifying mechanisms governing the establishment and spread of invasive species is a fundamental challenge in invasion biology. Because species invasions are frequently observed only after the species presents an environmental threat, research identifying the contributing agents to dispersal and subsequent spread are confined to retrograde observations. Here, we use a combination of seasonal surveys and experimental approaches to test the relative importance of behavioral and abiotic factors in determining the local co-occurrence of two invasive ant species, the established Argentine ant (Linepithema humile Mayr) and the newly invasive Asian needle ant (Pachycondyla chinensis Emery). We show that the broader climatic envelope of P. chinensis enables it to establish earlier in the year than L. humile. We also demonstrate that increased P. chinensis propagule pressure during periods of L. humile scarcity contributes to successful P. chinensis early season establishment. Furthermore, we show that, although L. humile is the numerically superior and behaviorally dominant species at baits, P. chinensis is currently displacing L. humile across the invaded landscape. By identifying the features promoting the displacement of one invasive ant by another we can better understand both early determinants in the invasion process and factors limiting colony expansion and survival.
Direct delay reductions of the Toda hierarchy
Nalini Joshi,Paul E. Spicer
Physics , 2009, DOI: 10.1143/JPSJ.78.094006
Abstract: We apply the direct method of obtaining reductions to the Toda hierarchy of equations. The resulting equations form a hierarchy of ordinary differential difference equations, also known as delay-differential equations. Such a hierarchy appears to be the first of its kind in the literature. All possible reductions, under certain assumptions, are obtained. The Lax pair associated to this reduced hierarchy is obtained.
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