Fast, scalable master equation solution algorithms. III. Direct time propagation accelerated by a diffusion approximation preconditioned iterative solver

In this paper we propose a novel fast and linearly scalable method for solving master equations arising in the context of gas-phase reactive systems, based on an existent stiff ordinary differential equation integrator. The required solution of a linear system involving the Jacobian matrix is achieved using the GMRES iteration preconditioned using the diffusion approximation to the master equation. In this way we avoid the cubic scaling of traditional master equationsolution methods and maintain the low temperature robustness of numerical integration. The method is tested using a master equation modelling the formation of propargyl from the reaction of singlet methylene with acetylene, proceeding through long lived isomerizing intermediates

Turbulence transport throughout the heliosphere

We employ a turbulence transport model to compute distributions of turbulence throughout the heliosphere. The model determines the radial dependence of three (coupled) quantities that characterize interplanetary turbulence, the energy per unit mass, the cross helicity or Alfvénicity, and a similarity length scale. A fourth integrated quantity, the plasma temperature, is modified by heat deposition due to turbulent dissipation. The model includes advection, expansion, and reflection effects as well as the tendency toward dynamic alignment, and a von Kármán type dissipation function that represents decay of turbulence due to cascade to small scales. Two types of forcing are also featured, one a simple model of stream shear, and the other a driving in the outer heliosphere associated with wave energy injection due to pickup protons of interstellar origin. Parameters for the model have been tuned using observation data from Voyager and Ulysses. We analyze the constraining observations to provide boundary conditions and parameters that vary with heliocentric latitude, with some extrapolations. The fully assembled model permits the computation of the distribution of turbulence throughout the entire heliosphere, and we present solutions for several appropriate parameter sets

Effects of J-gate potential and interfaces on donor exchange coupling in the Kane quantum computer architecture

We calculate the electron exchange coupling for a phosphorus donor pair in silicon perturbed by a J-gate potential and the boundary effects of the silicon host geometry. In addition to the electron-electron exchange interaction we also calculate the contact hyperfine interaction between the donor nucleus and electron as a function of the varying experimental conditions. Donor separation, depth of the P nuclei below the silicon oxide layer and J-gate voltage become decisive factors in determining the strength of both the exchange coupling and the hyperfine interaction - both crucial components for qubit operations in the Kane quantum computer. These calculations were performed using an anisotropic effective-mass Hamiltonian approach. The behaviour of the donor exchange coupling as a function of the device parameters varied provides relevant information for the experimental design of these devices.Comment: 15 pages, 15 figures. Accepted for Journal of Physics: Condensed Matte

Exercise for the Treatment of Knee Osteoarthritis

Regular exercise reduces osteoarthritic knee pain and improves functioning. (Strength of Recommendation: A, based on systematic reviews.) Aerobic and strength-training exercises, including land- and water-based exercises, are effective for treating knee osteoarthritis. (Strength of Recommendation: A, based on a randomized controlled trial [RCT].

Exchange and Specialisation as a Discovery Process

In this article we study the performance of an economy that can support specialisation if the participants develop and follow some system of exchange. We define a closed economy in which the participants must discover the ability to exchange, implement it, and ascertain what they are comparatively advantaged in producing. Many of our participants demonstrate the ability to find comparative advantage, capture gains from trade and effectively choose production that is consistent with the choices of others. We explore various treatments to provide insight into the conditions that foster the growth of specialisation and exchange within this weak institutional framework

An Analysis Of Brand Equity Determinants: Gross Profit, Advertising, Research, And Development

The topic of brand equity continues to be of great importance to private sector firms in the creation and development of both product and company brand strategy. This study analyzes the relationship of different variables and brand equity with the purpose of providing useful insight into brand management and advancement. This research approach is unique in its use of private sector generated measures of brand equity as the main data source. The methodology entails collecting financial information from a list of publicly traded companies evident on the annual Interbrand ranking of top brand values, then executing statistical analysis using correlation and regression. Results make evident a significant positive correlation between brand equity and gross profit, advertising expense, and research and development expense. However, findings reveal that advertising is not as important a driver of brand equity in the short-term as put forward in previous research and evidence suggesting the presence of dynamics and non-linear effects exists.&nbsp

Defining Inclusionary Practices in Catholic Schools

The purpose of this article is to provide Catholic educators, administrators, families, and broader parish communities an understanding of critical elements required to effectively include all students, particularly those with disabilities, in Catholic schools. With an understanding that Catholic schools enroll and will continue to add not only students with disabilities, but also other students who may struggle with learning in some manner, the Catholic school community needs to keep abreast of effective practices that facilitate meaningful inclusion. This is especially relevant for those Catholic families who desire a Catholic education for their children with disabilities, as well as their typically developing children. This article seeks to: (a) offer a rationale for the need to include all learners in our Catholic schools through the reinforcement of Catechetical teachings, (b) define inclusion in Catholic education, (c) outline characteristics of high quality, inclusive schools, (d) review relevant research on inclusion that is applicable to the needs of our Catholic school environments, and (e) provide a case study of an effective, inclusive Catholic school to further contextualize to the field what is not only possible, even given limited resources, but what is happening in today’s Catholic school settings

Mismorphism: a Semiotic Model of Computer Security Circumvention (Extended Version)

In real world domains, from healthcare to power to finance, we deploy computer systems intended to streamline and improve the activities of human agents in the corresponding non-cyber worlds. However, talking to actual users (instead of just computer security experts) reveals endemic circumvention of the computer-embedded rules. Good-intentioned users, trying to get their jobs done, systematically work around security and other controls embedded in their IT systems. This paper reports on our work compiling a large corpus of such incidents and developing a model based on semiotic triads to examine security circumvention. This model suggests that mismorphisms---mappings that fail to preserve structure---lie at the heart of circumvention scenarios; differential perceptions and needs explain users\u27 actions. We support this claim with empirical data from the corpus

Ampliando a brecha: A desigualdade na distribuição de recursos para a educação científica nos níveis K-12

Inequalities in educational opportunity are well documented. Regardless of the nature of the disadvantage—low income, underrepresented minority status, or prior achievement—students from backgrounds associated with a given disadvantage have less access to educational opportunities. In this article, we use data from the 2012 National Survey of Science and Mathematics Education to explore how resources are allocated for science instruction specifically. We focus on how three kinds of resources—well-prepared teachers, material resources, and instruction itself—are allocated to classes that are homogeneously grouped by prior achievement level. Regardless of the resource, we find that classes of students with low prior achievement (as perceived by their teachers) have less access. Some of the differences are striking, particularly regarding access to material resources, while others are more subtle. There is also evidence that some policies do not impact teachers equally. For example, time allowed for teacher professional development is perceived differently by teachers in terms of its impact depending on the achievement level of students in the class. The study supports the assertion that what is known about ability grouping in general applies in science instruction specifically. When students with low prior achievement are grouped together, their classes have less access to critical resources for science learning opportunities, potentially widening the gap between them and their higher-achieving peers.Las desigualdades en las oportunidades educativas están bien documentadas. Independientemente de la naturaleza de la desventaja -- baja renta, condición de minoría subrepresentada, o de logros anteriores-- estudiantes asociados con alguna condición de desventaja tienen menos acceso a oportunidades educativas. En este artículo, utilizamos datos de la Encuesta Nacional  de Ciencia y Educación Matemática de 2012 para explorar cómo se asignan los recursos para la enseñanza de las ciencias. Nos centramos en cómo tres tipos de recursos -maestros bien preparados, recursos materiales, y la instrucción en sí, se asignan a las clases que se agrupan homogéneamente por nivel de logro anterior. Independientemente del recurso, nos encontramos con que las clases de estudiantes con bajo rendimiento previo (según la percepción de sus maestros) tienen menos acceso. Algunas de las diferencias son sorprendentes, sobre todo con respecto al acceso a los recursos materiales, mientras que otras son más sutiles. También hay evidencia de que algunas políticas no afectan a los docentes por igual. Por ejemplo, el tiempo permitido para el desarrollo profesional de los docentes que se percibe de manera diferente por los profesores en términos de su impacto en función del nivel de logro de los estudiantes en la clase. El estudio apoya la afirmación de que lo que se sabe acerca de la capacidad de agrupación en general se aplica en la enseñanza de la ciencia en particular. Cuando los estudiantes con bajo rendimiento son agrupados, sus clases tienen menos acceso a los recursos críticos para ampliar las oportunidades de aprendizaje de ciencias, lo que podría incrementar la brecha entre ellos y sus compañeros de mayores logros educativos.As desigualdades de oportunidades educacionais estão bem documentadas. Independentemente da natureza da desvantagem - baixa renda, status de minoria sub-representada ou resultados anteriores - estudantes associados a uma condição de desvantagem têm menos acesso a oportunidades educacionais. Neste artigo, usamos dados da Pesquisa Nacional de Ciência e Educação Matemática de 2012 para explorar a forma como os recursos são alocados para a educação científica. Nós nos concentramos em três tipos de- recursos --professores bem preparados, recursos materiais, e da própria instrução, e como são atribuídos a classes agrupados por nível de resultados anteriores. Independentemente da aplicação, verificamos que as turmas de alunos com baixo aproveitamento anterior (pela percepção dos professores) têm menos acesso. Algumas das diferenças são marcantes, especialmente no que diz respeito ao acesso a recursos materiais, enquanto outros são mais sutis. Há também evidências de que algumas políticas não afetam docentes da mesma maneira. Por exemplo, o tempo permitido para o desenvolvimento profissional de professores é percebido de forma diferente pelos professores em termos do seu impacto sobre o nível de desempenho do aluno na sala de aula. O estudo apoia o que se sabe geralmente sobre as politicas de agrupamento aplicado no ensino da ciência em particular. Quando os alunos de baixo desempenho são agrupados, suas aulas têm menos acesso a recursos essenciais para aumentar as oportunidades de aprendizagem das ciências, o que poderia aumentar a distância entre eles e os seus pares mais alto nível de instrução