I Wish There Was A Wireless To Heaven : Then Mama Would Not Seem So Far Away

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Techniques to Understand Computer Simulations: Markov Chain Analysis

The aim of this paper is to assist researchers in understanding the dynamics of simulation models that have been implemented and can be run in a computer, i.e. computer models. To do that, we start by explaining (a) that computer models are just input-output functions, (b) that every computer model can be re-implemented in many different formalisms (in particular in most programming languages), leading to alternative representations of the same input-output relation, and (c) that many computer models in the social simulation literature can be usefully represented as time-homogeneous Markov chains. Then we argue that analysing a computer model as a Markov chain can make apparent many features of the model that were not so evident before conducting such analysis. To prove this point, we present the main concepts needed to conduct a formal analysis of any time-homogeneous Markov chain, and we illustrate the usefulness of these concepts by analysing 10 well-known models in the social simulation literature as Markov chains. These models are: • Schelling\'s (1971) model of spatial segregation • Epstein and Axtell\'s (1996) Sugarscape • Miller and Page\'s (2004) standing ovation model • Arthur\'s (1989) model of competing technologies • Axelrod\'s (1986) metanorms models • Takahashi\'s (2000) model of generalized exchange • Axelrod\'s (1997) model of dissemination of culture • Kinnaird\'s (1946) truels • Axelrod and Bennett\'s (1993) model of competing bimodal coalitions • Joyce et al.\'s (2006) model of conditional association In particular, we explain how to characterise the transient and the asymptotic dynamics of these computer models and, where appropriate, how to assess the stochastic stability of their absorbing states. In all cases, the analysis conducted using the theory of Markov chains has yielded useful insights about the dynamics of the computer model under study.Computer Modelling, Simulation, Markov, Stochastic Processes, Analysis, Re-Implementation

Multipower variation for Brownian semistationary processes

In this paper we study the asymptotic behaviour of power and multipower variations of processes $Y$:$$Y_t=\int_{-\in fty}^tg(t-s)\sigma_sW(\mathrm{d}s)+Z_t,$$ where $g:(0,\infty)\rightarrow\mathbb{R}$ is deterministic, $\sigma >0$ is a random process, $W$ is the stochastic Wiener measure and $Z$ is a stochastic process in the nature of a drift term. Processes of this type serve, in particular, to model data of velocity increments of a fluid in a turbulence regime with spot intermittency $\sigma$. The purpose of this paper is to determine the probabilistic limit behaviour of the (multi)power variations of $Y$ as a basis for studying properties of the intermittency process $\sigma$. Notably the processes $Y$ are in general not of the semimartingale kind and the established theory of multipower variation for semimartingales does not suffice for deriving the limit properties. As a key tool for the results, a general central limit theorem for triangular Gaussian schemes is formulated and proved. Examples and an application to the realised variance ratio are given.Comment: Published in at http://dx.doi.org/10.3150/10-BEJ316 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

Examining Retirement Housing Preferences Among International Retiree Migrants

Housing demand models based on individual consumers' utility function reflect preferences about the structure and lot, neighborhood, and location as related to socioeconomic characteristics of the occupants. As a growing proportion of aging residents in many countries are undertaking late life moves, their preferences will have an influence on destination housing markets. We examine the characteristics, attitudes and preferences about retirement housing among immigrant retirees currently living in traditional housing in a retirement destination in Alicante, Spain. Using results from a survey of German and British retirees living in the region, we find through logistic regression that preference for retirement housing is associated with aging and gaining access to in-home support services.Housing preferences; Demographic trends; Seniors housing

Supervisionar para delinear a mudan?a : do conhecimento da autoavalia??o ? interven??o

Disserta??o de Mestrado em Supervis?o Pedag?gica apresentada na Escola Superior de Educa??o do Instituto Polit?cnico de Viana do CasteloNa atualidade, muitas das nossas escolas confrontam-se com a necessidade de encontrar mecanismos de avalia??o interna para a sua pr?pria autorregula??o. A ado??o do modelo CAF (Common Assessment Framework), pelo Agrupamento em estudo, para al?m de cumprir o definido na Lei n? 31/2002, fomentou a probabilidade em reconhecer as suas fragilidades ou inclusivamente refor?ar as ?reas mais conseguidas, atrav?s da verifica??o dos seus pontos fortes e, ou ?reas de melhoria. Assume assim a avalia??o interna, uma relev?ncia preponderante para o Agrupamento, uma vez que, a partir destas intencionalidades, ? poss?vel desenvolver uma estrat?gia de aperfei?oamento pedag?gico, administrativo e organizacional entre outros aspetos. Nesta perspetiva, a supervis?o constitui uma responsabilidade de todos os que assumem fun??es de lideran?a na escola, ao servi?o da mobiliza??o, do apoio, da coordena??o, da forma??o e da gest?o, tendo sempre por finalidade facilitar a a??o dos agentes educativos, fomentar as suas potencialidades e favorecer a realiza??o dos prop?sitos tra?ados para a organiza??o. Emana destes des?gnios, o presente estudo, com a exig?ncia em compreender atrav?s de um olhar supervisivo as pr?ticas efetuadas, atrav?s de uma primeira experi?ncia tida em 2009/2010, com o modelo CAF, num Agrupamento de Escolas, firmado nos seguintes objetivos: contribuir para a compreens?o do modelo CAF no Agrupamento, identificar as perce??es das diferentes lideran?as sobre a forma como foi cumprida a implementa??o do modelo, determinar situa??es que possam produzir mudan?as na forma como ? aplicado o modelo CAF e propor novas atitudes de debate e reflex?o frente ? autoavalia??o da escola. Para o efeito recorreu-se a uma metodologia de car?ter qualitativo com um design de estudo de caso, tendo sido utilizadas as seguintes t?cnicas para a recolha do material emp?rico: a an?lise documental, a entrevista semiestruturada e as notas de campo. Escolheu-se a An?lise de Conte?do como a t?cnica de organiza??o e tratamento de dados. Os principais resultados obtidos denunciam a aus?ncia de planos de melhoria, o que manifesta uma interrup??o dos passos previstos pela CAF, dando a entender que os procedimentos assumiram uma praxe legitimadora, da mesma maneira que se expressam algumas lacunas nos procedimentos utilizados. Destes surgem entre outros o desconhecimento do modelo, aus?ncia de forma??o, desvaloriza??o dos processos comunicativos, n?o envolvimento da comunidade na equipa de trabalho, inexist?ncia de planos de trabalho. Concebe-se que se desaproveitou uma oportunidade, visto que o pr?prio modelo era sentido como algo de novo. A mudan?a ? imprescind?vel para que a vida nas organiza??es encontre um melhor caminho, o seu caminho, ? pan?plia de solicita??es com que presentemente se defrontam. A pretens?o em reorientar a escola s? poder? ser ganha, mediante a dinamiza??o de uma reflex?o profunda e alargada. S? assim a escola ser?, capaz de se autogovernar e autorregular, de modo a responder, com efici?ncia ecol?gica, aos problemas concretos que se lhe colocam no percurso da sua a??o educativa.Nowadays, many of our schools face the necessity of finding internal evaluation tools for their self regulation. The adoption of the model CAF (Common Assessment Framework) by the cluster of schools in study, besides fulfiling the law nr. 31/2002, promoted the possibility of recognizing its fragilities or even to reinforce the most achieved areas through the checking of its strong points and, or possible areas of improvement. So, the internal evaluation plays an important role for the cluster of schools, since from these intentions, it is possible to develop a pedagogical administrative and organizational improvement strategy, among other aspects. According to this point of view, the supervision is a responsibility of all those that have leadership functions at school, serving the mobilization, the support, the coordination, the formation and the management , having always the purpose to facilitate the action of the educational agents , to promote their potentialities and to favour the realization of the outlined purposes for the organization. So, from this intention, emanates the present study , with the exigency to understand the daily practice through a supervisive sight with a first experience in 2009/2010, with the model CAF, in a cluster of schools, with the following objectives: to contribute for the understanding of that model, to identify the perception of the different leaderships about the way how it was carried out the implementation of the model, to determine situations that can produce changes in the way how the model CAF is applied and propose new attitudes of debating and reflexion towards the self evaluation of school. For this purpose, it was applied a methodology of qualitative nature with a design of case study, using the following technical tools for the gathering of empiric material: the documental analysis, the semi-structured interview and field notes. It was chosen the Analysis of Contents as a technical of organization and data treatment. The main results got, reveal the lack of improvement plans, what prove an interruption of the steps foreseen by the CAF model, showing that the procedures assumed a legitimated praxis, in the same way that express some gaps in the procedures that were used. From these arise, among others, the lack of knowledge of the model, the lack of formation, the devaluation of the communicative processes, no involvement of the community in the group of work and the lack of work plans. In this way it is assumed that was wasted an opportunity, since the model was seen as something new. The change is essential so that the life of the organizations can find a better way, their way, to answer the great number of requests that they are facing nowadays. The aim of re-guiding the school only can be reached by means of a dynamic process of a deep and wide reflexion. Only in this way, the school will be able to self govern and self regulate so as to answer, with ecological proficiency, to the real problems that occur in its educative action

WO3-decorated ZnO nanostructures for light-activated applications

In the present work, a two-step vapor-phase route was implemented for the tailored design of ZnO\u2013WO3 nanoheterostructures supported on fluorine-doped tin oxide (FTO) substrates. Under optimized conditions, the sequential use of chemical vapor deposition (CVD) and radio frequency (RF)-sputtering for the deposition of zinc and tungsten oxides respectively, resulted in the growth of calyx-like ZnO nanostructures uniformly decorated by a conformal dispersion of low-sized WO3 nanoparticles. The target materials were characterized by means of a multi-technique approach, with particular regard to their structural, compositional, morphological and optical properties. Finally, their photocatalytic performances were preliminarily tested in the abatement of NOX gases (NO and NO2). Due to the unique porous morphology of the ZnO nanodeposit and the high density of ZnO\u2013WO3 heterojunctions, WO3-decorated ZnO revealed appealing De-NOX characteristics in terms of both degradation efficiency and selectivity. Such features, along with the photoinduced superhydrophilicity and self-cleaning properties of the present nanomaterials, candidate them as promising functional platforms for applications in smart windows and building materials for environmental remediation

Errors and Artefacts in Agent-Based Modelling

The objectives of this paper are to define and classify different types of errors and artefacts that can appear in the process of developing an agent-based model, and to propose activities aimed at avoiding them during the model construction and testing phases. To do this in a structured way, we review the main concepts of the process of developing such a model – establishing a general framework that summarises the process of designing, implementing, and using agent-based models. Within this framework we identify the various stages where different types of errors and artefacts may appear. Finally we propose activities that could be used to detect (and hence eliminate) each type of error or artefact.Verification, Replication, Artefact, Error, Agent-Based Modelling, Modelling Roles