Escape from attracting sets in randomly perturbed systems

The dynamics of escape from an attractive state due to random perturbations is of central interest to many areas in science. Previous studies of escape in chaotic systems have rather focused on the case of unbounded noise, usually assumed to have Gaussian distribution. In this paper, we address the problem of escape induced by bounded noise. We show that the dynamics of escape from an attractor's basin is equivalent to that of a closed system with an appropriately chosen "hole". Using this equivalence, we show that there is a minimum noise amplitude above which escape takes place, and we derive analytical expressions for the scaling of the escape rate with noise amplitude near the escape transition. We verify our analytical predictions through numerical simulations of a two-dimensional map with noise.Comment: up to date with published versio

Liberdade e coação no direito de Kant

Kant divide a filosofia moral em duas partes: Ética e Teoria da Justiça. Cada uma é compota de diferentes descrições de deveres e direitos. A ética contém deveres e direitos internos, voluntários e não-coercitivos. A teoria da justiça contém deveres e direitos externos e coercitivos. Os dois tipos de deveres e direitos são definidos em sua relação um com o outro. O que distingue os deveres éticos, ou deveres de virtude, dos deveres jurídicos, é que a compulsão externa para o dever de virtude é baseado na livre coerção própria. Assim, a finalidade deste artigo é pesquisar a noção de dever, e a relação entre dever, liberdade e coaçã

Signatures of fractal clustering of aerosols advected under gravity

Aerosols under chaotic advection often approach a strange attractor. They move chaotically on this fractal set but, in the presence of gravity, they have a net vertical motion downwards. In practical situations, observational data may be available only at a given level, for example at the ground level. We uncover two fractal signatures of chaotic advection of aerosols under the action of gravity. Each one enables the computation of the fractal dimension $D_{0}$ of the strange attractor governing the advection dynamics from data obtained solely at a given level. We illustrate our theoretical findings with a numerical experiment and discuss their possible relevance to meteorology.Comment: Accepted for publication in Phys. Rev. E (Rapid Communications

The reality of Engineering Research Methodology

En el Perú, hay numerosos expertos en metodología de la investigación científica; no obstante, muy pocos son profesionales de ingeniería. Además, numerosos libros relacionados con la temática (por ejemplo [1], [2]) están orientados a las ciencias sociales y muy poco o nada tratan sobre problemas de ingeniería; por lo tanto, todos los conceptos de la metodología son a nivel teórico para esta disciplina. Como consecuencia, los estudiantes de ingeniería tienen dificultades en preparar un proyecto de investigación por la falta de guías y orientadores en una metodología adecuada para su carrera. Los problemas para aplicar una metodología de investigación en el área de ingeniería son diversos. A continuación, se muestran algunos de estos problemas y los criterios a considerar para superar estos inconvenientes.El primer problema es la confusión al aplicar los instrumentos de medición, como, por ejemplo, si se evalúa la eficiencia energética de un sistema mecatrónico, no podrían utilizarse encuestas o entrevistas, sino aquellos elementos que midan la energía de entrada y el trabajo útil producido por el sistema. Estos instrumentos no se diseñan ni se validan, como se debe hacer con las encuestas y entrevistas, porque ya vienen de fábrica listos para ser utilizados en los laboratorios, sin embargo, sí se requiere seleccionar los más adecuados.El segundo problema es la confusión en el análisis de datos. En esta etapa, normalmente interesa saber si existe correlación y si la influencia es positiva o negativa; en ingeniería, en la mayoría de los problemas, hay certeza de la existencia de correlación y si es positiva o negativa porque todo el conocimiento de física y química nos apoya; por lo tanto, la investigación debe orientarse a encontrar el modelo matemático (en base a estas disciplinas) que describa el fenómeno. Por ejemplo, Hallar la relación que existe entre el flujo de aire en un colector solar y la cantidad de energía absorbida por el aire; se sabe que a mayor flujo es mayor la transferencia de calor por convección, sin embargo, se debe determinar cuál es el modelo matemático (establecer la estructura y constantes del modelo) que describa el comportamiento del colector solar en estudio con respecto a estas variables.El tercer problema es un trato diferente en la toma de muestras. Así, cuando deseamos conocer la resistencia de un material compuesto nuevo, se deben tomar probetas y someterlas a ensayos de tracción, flexión y compresión. En este caso las muestras son las probetas y la población es todo el material compuesto, cuya estructura está dentro de las características del material nuevo. Por lo tanto, la población es infinita. Esto es atípico en los ejemplos de los libros de metodología de la investigación.El cuarto problema es que normalmente los ingenieros crean soluciones a problemas de ingeniería y, por lo tanto, los estudiantes de ingeniería tienden a ello. Sin embargo, la mayoría de libros de metodología de la investigación no especifica en qué etapa de la investigación se crea la solución. En ingeniería se maneja un método de investigación poco tratado en los libros: la investigación tecnológica [3]-[5] o también conocida como desarrollo tecnológico. Numerosas tesis e investigaciones tratan del diseño de un prototipo, software, estructura, etc. para un caso en particular [6]-[9]. Estas tesis e investigaciones sobre desarrollo tecnológicos siguen una metodología de diseño, por ejemplo: se identifica una necesidad (el problema), se investigan las soluciones existentes de problemas relacionados, se plantean soluciones, se selecciona la propuesta de solución más adecuada utilizando cálculos para evaluarlos, se implementa la solución en simulación o en un prototipo y se evalúa.Es importante tomar en cuenta estos criterios al momento de aplicar una metodología de investigación para Ingeniería, a fin de evitar complicaciones y/o, en el peor de los casos, reiniciar la investigación.In Perú, there are many experts on Scientific Research Methodology, however, a ew of them are Engineer. Furthermore, most of the books of research methodology (for example [1], [2]) are focused to social science and contain insignificant quantity or nothing of engineering problems, thus, the methodology concepts are only in theory level in Engineering. As consequence, the engineering students have difficulties to elaborate a research project because the miss of handbooks and guides in a suitable methodology for Engineering. The problems to apply an Engineering Research Methodology are many. These problems and the criterions to consider to face them are shown as follows.The first problem is the confusion in applying the measurement instruments, for example, if the energy efficiency is evaluated in a mechatronics system, the instruments cannot be questionnaires or interviews, they have to be instruments that measure the input energy and the usable work produced by the system; these instruments are not designed or validated, as it is made with questionnaires or interviews, because the factories supply them ready to use in the laboratories, although, they have to be selected.The second problem is the confusion in the data analysis. In this stage, generally, the objective is to know the correlation between variables and if it is positive or negative; however, in engineering, the existence of positive or negative correlation is known in most of the problems because the knowledge of physics and chemistry sustain this, thus, the research have to be oriented to obtain the mathematic model based in physics and chemistry to describe the phenomenon. For example, obtain the relation between the air flow in a solar collector and the quantity of absorbed energy by the air; it is known for transfer heat theory that more convection heat transfer is obtained when the air flow increase, but, the mathematical model has to be identified (define structure and calculate parameters) to describe the behavior of the solar collector respect to the variables in study.The third problem is a different treatment to take the samples. For example, when the resistance of a new composite material wants to be known, specimens of the material have to be subjected to tension, flexion and compression testing. In this case the samples are the specimens and the population are every composite material with structure between the characteristics of the new composite material. Therefore, the population is infinite. This is untypical in examples of research methodology books.The fourth problem is that normally the engineers create its problem solutions in the field of Engineering, therefore, the engineering students tends to do that. However, most of the books of research methodology do not clarify in what stage of the investigation methodology the solution is created. A research method is used in Engineering called the Technology Research [3] – [5] or Technology Development but this theme is taken just a little in the books. Many of the thesis and research made a design of a prototype, software, structure, and others for a particular case [6] – [9]. These thesis and research are Technology Developments that follow a Design Methodology, for example: a necessity is identified that will be the problem, a research of the current solutions of related problems is performed, solutions are proposed, the best solution is selected using calculus to evaluate them, the solution is implemented in simulation or in a prototype, and finally, the solution is evaluated.It is important to take into account these criteria at the moment to apply a Research Methodology for Engineering, thus avoid complications and in the worst case restart the research

Examining good practices in digital content marketing: a study on Portuguese hotel blogs

Este estudo examina o uso do marketing de conteúdo digital por parte de hotéis portugueses nos seus blogues. São analisadas boas práticas que a literatura aponta que devem ser utilizadas em blogues para que estes sejam bem-sucedidos na relação com o utilizador. Estas boas práticas sustentam-se no uso de aspetos específicos que beneficiam a gestão do blogue. O estudo oferece uma visão do nível da adoção dessas boas práticas/aspetos por parte de 22 hotéis analisados. O estudo é motivado pela escassez de informação existente sobre hotelaria portuguesa e o uso que esta faz do marketing de conteúdo digital nos seus blogues. Foram encontrados estudos que evidenciam a importância do marketing de conteúdo digital e a sua estreita ligação aos blogues noutras áreas, mas verifica-se uma lacuna na investigação deste tópico aplicado à hotelaria. Desta forma, este estudo centra-se em analisar como o marketing de conteúdo digital é utilizado nos blogues de hotéis portugueses. Os dados foram recolhidos através de um website gerido pelo Turismo de Portugal, no qual foi possível extrair-se uma lista de hotéis de 4 e 5 estrelas. Desta forma, foram identificados 198 websites de hotéis de 5 estrelas e 795 websites de hotéis de 4 estrelas, de forma a registar todos os hotéis que incorporavam blogues nos seus sites. Após esta fase preliminar, foi reunida uma amostra de 22 hotéis com blogues, nos quais se analisou seis dos seus mais recentes artigos/posts. Para o efeito, foi realizada uma análise de conteúdo dos mesmos, com uma aplicação quantitativa. Foram reunidas e analisadas 11 categorias principais e em alguns casos subcategorias, nomeadamente 1) “conteúdo educativo” (webinars, infográficos e e-books), 2) “credibilidade” (nome do autor), 3) “utilidade” (viagens/férias, dicas, lugares a visitar, relacionado ao negócio), 4) “relevância” (categorias), 5) “consistência”, 6) “atual”, 7) “cativante” (podcasts, vídeos, áudio, animações e imagens), 8) “comentários”, 9) “dimensão do texto”, 10) “botões de partilha” e 11) “artigos sugeridos”. A análise permitiu verificar que existe uma escassez de hotéis de 4 e 5 estrelas em Portugal com blogue no seu website, de acordo com os critérios usados no presente estudo. Além disso, algumas das categorias analisadas, como “conteúdo educacional” e suas subcategorias, nomeadamente webinars, infográficos e e-books, não estão a ser utilizados pelos blogues dos hotéis analisados. Ademais, na categoria analisada onde se tenta perceber se o conteúdo é “cativante” (engaging), relativamente às suas subcategorias, nomeadamente podcasts, vídeos, áudio, animações e imagens, concluiu-se que esta última subcategoria (imagens) é a mais adotada pela grande maioria dos hotéis nos posts dos seus blogues. Verificou-se que dos 22 hotéis, 21 (95%) utilizam imagens nos seus blogues. O uso das outras subcategorias é quase residual. Embora a literatura aponte como importante exibir o nome do autor do post/artigo no final do mesmo como forma de dar mais credibilidade, apenas 4 blogues (18%) incluem esta característica. Relativamente à atenção dada ao grau de “utilidade” (value) dos posts para os utilizadores, verificou-se que apenas 2 dos blogues analisados (9%) fazem melhor uso desta característica de forma consistente. Cerca de 41% recorrem a esta boa prática mas não de forma consistente. Com respeito à característica que indica que o blogue deve dar a possibilidade ao utilizador de escolher entre diferentes categorias (relevância), verificou-se que apenas 7 hotéis (32%) fazem uso desta opção. Verificou-se também que é importante que os blogues façam uma partilha regular de posts/artigos. Nesta categoria foi verificada a sua consistência ao longo do tempo. Os resultados apontam que 7 blogues (32%) partilham posts de forma consistente. Analisou-se se os blogues partilham posts que sejam atuais e que estejam ligados a eventos recentes. Verificou-se que 16 blogues (73%) partilharam posts que aplicam esta boa prática de marketing de conteúdo digital. Relativamente à característica que se refere à possibilidade de os utilizadores deixarem comentários nos posts, constatou-se que apenas 2 blogues (9%) permitem que o utilizador deixe comentários, o que não é consistente com a ideia de interatividade esperada ao nível do marketing de conteúdos digitais aplicado aos blogues. Com respeito à dimensão do texto dos posts, a literatura enfatiza a recomendação de que estes devem ter um mínimo de extensão de 500 palavras. Nesta característica, “dimensão do texto”, verificou-se que apenas 2 blogues (9%) são consistentes em todos os posts analisados. Embora alguns blogues partilhem artigos que respeitam este número de palavras, estes não são consistentes em todos os posts analisados Analisou-se se os blogues dos hotéis incorporavam um botão (share button) diretamente nos posts que permitisse a que os utilizadores pudessem partilhar o post nas suas redes sociais. Aqui analisaram-se 3 redes sociais diferentes, nomeadamente Facebook, LinkedIn e Twitter, assim como a possibilidade de partilha via email. Constatou-se que 9 blogues (41%) permitem partilhar artigos diretamente no Facebook, seguido pelo Twitter, com 8 blogs (36%), LinkedIn com 6 blogs (27%) e e-mail com 5 blogs (23%). Os resultados indicam também se os blogues fazem a sugestão de leitura de outros posts relacionado no próprio post que o utilizador leia. Desta forma, observou-se que 16 blogues (73%) aplicam esta boa prática. Este estudo revelou que as boas práticas analisadas são importantes para que os hotéis possam otimizar os seus blogues a nível da estratégia de comunicação digital, por conseguinte, tornar a sua relação com os utilizadores mais próxima. Do que foi analisado, constata-se que nenhum blogue reúne todas as categorias e subcategorias examinadas. No entanto, existem pelo menos 2 hotéis que sobressaem em comparação com os demais, como aplicando o maior número de boas práticas de marketing de conteúdos digitais em blogues. De uma forma geral, a maioria dos blogues não segue as práticas recomendadas na literatura de forma consistente, não estando, dessa forma, a usufruir de todos os benefícios de uma estratégia de comunicação digital por via desta ferramenta. Este estudo contribui para a literatura de marketing de conteúdo digital com aplicação em blogues de hotéis. Preenche uma lacuna existente ao nível do conhecimento, investigando de forma exaustiva o uso do marketing de conteúdo digital no uso de blogues que geridos por hotéis de 4 e 5 estrelas em Portugal. A metodologia usada pode ser usada no futuro no âmbito de outras tipologias de alojamento. Além disso, esta investigação enfatiza para a importância do uso de blogues de forma consistente e estruturada. Recomendações de marketing são oferecidas com o foco na gestão de marketing de hotéis com recurso a blogues.The main objective of this study is to examine if companies such as hotels follow the best practices recommended in digital content marketing (DCM) literature in relation to their blogs. More specifically, it is intended to analyze if the content shared by Portuguese hotels on their blogs adhere to the elements that literature highlights as important for developing engagement with the audience. In so doing, 22 hotel blogs were compared by highlighting the ones that follow the best practices and the reverse situation. This study is motivated by the scarcity of existing research on Portuguese hotels and their use of digital content marketing on their blogs. A content analysis approach using 11 categories (characteristics identified in literature) revealed that the good practices analyzed are important so that hotels optimize their blogs and, therefore, improve their relationship with users. The findings show that no blog brings together all the good practices examined. Of all the hotels studied, 2 hotel blogs stand out in comparison to the others by implementing the characteristics that literature points out as relevant in a good digital communication strategy via blogs. In general, the majority of blogs do not follow the practices recommended in literature in a consistent way, and therefore are not optimizing their blogs as a communication tool. This study contributes significantly to the digital content marketing literature with application on hotel blogs. It fills an existing research gap, by examining the use of digital content marketing via blogs in a hospitality context, with a focus on 4 and 5 star hotels. As a result, this research offers marketing recommendations addressed to hotels, considering the use of DCM with regards to blogs

Agility and Resilience as Sources of Competitive Advantages a Theoretical and Empirical Investigation

Today’s hypercompetitive global climate makes lasting competitive edge unsuitable. Firms face increasing complexity due to the rapid entry and growth of internationalizing firms from emerging markets, technological breakthroughs, discontinuous innovation, and the uncertainties surrounding unexpected shocks transmitted across world markets, such as the Covid-19 pandemic. In this research, I examine how firms have built and applied two adaptive abilities (agility and resilience) to respond to environmental changes and disruptions to create sustainable competitive advantage. An agile organization is simultaneously a resilient organization. Despite agility’s increased relevance in the academy and practitioners\u27 publications, its epistemological and ontological analyses are superficial at best. Specifically, supported by inductive and deductive analysis, I bring clarity to agility’s concept and its boundary conditions. Thus, I propose an integrative multilevel framework of the antecedents, the enablers, and the outcomes of the process of agility performance. Moreover, through in-depth interviews with executives, I explore how agility and resilience manifested in emerging market multinational firms (EMNEs) enhance their competitiveness by using both adaptive abilities in their international operations. The findings reveal that all organizations possess some degrees of agility and resilience simultaneously as two faces of the same coin. Furthermore, agility and resilience are interdependent, comprising five common domains

A 1H NMR Network Approach for the Study of Specialized Metabolites: Development and Applications

The history of the World could not be told without mentioning specialized metabolites. Long before we had the notion of organic molecules, we were already sailing across the oceans in the pursue of their valuable sources, and raising whole empires based on the economy of spices, tobacco and coffee. Our own survival and adaptability as a species can be credited to discoveries of nature-sourced drugs through the centuries, such as penicillin, paclitaxel and artemisinin. As our awareness towards the environment evolved, so did our perspective on these molecules, which are now recognized as important products and intermediates of the interaction between organisms and their ecosystems. It is not an overstatement thus, to affirm that in the light of an imminent environmental crisis, the study of specialized metabolites will be of fundamental importance for the preservation and recovery of biodiversity. The development of untargeted analytical techniques has greatly advanced our ability to investigate these compounds in their natural contexts. Among those, the application of Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy for chemical profiling enabled the recognition of compound structural features and facilitated the identification of unknown compounds even prior to the laborious work of isolation. However, because multiple resonance signals arise from a single compound, a considerable amount of overlap is observed in biological samples which can limit our ability to detect those key structural markers. There are certain NMR pulse experiments that can aid in deconvoluting these signals, but a more practical approach resides in the statistical treatment of the 1H NMR spectrum, in which regular variations across the spectrum are directly mapped to variables pertinent to the system in study, such as biological activity, biogeographical data, or phylogenetic classification. This document presents an innovative strategy in which gene co-expression network analysis is adapted for the statistical treatment of 1H NMR spectral data, resulting in the deconvolution of metabolite signals and simplification of the spectrum into a few variables. These variables represent statistically measurable chemical patterns that in conjunction with other measurements can support addressing a multitude of topics in Chemical Ecology. In Chapter 1, we describe the method development and validation in a controlled experiment with prepared mixtures of known compounds and demonstrate how it recognizes metabolite identity at different structural levels. We then demonstrate its applicability in the study of natural mixtures with the investigation of ontogenetic changes of metabolism in Piper kelleyi. In Chapter 2, we applied the method to the identification of biologically active compounds from a chemically heterogeneous set of 29 Piper extracts. By quantifying the association between chemical patterns and measurements of antifungal activity, we accurately identified specific targets for the isolation of antifungal compounds, while also establishing a framework to evaluate the effect of specific structural features in modulating the toxicity of different plant species. Finally, in Chapter 3, we adopted an untargeted approach to investigate the phylogenetic signal of specialized metabolites in a broader collection of Piper species. Based upon measurements of chemical similarity, we identified the chemical traits most strongly associated with the clade Schilleria, ultimately leading us to the characterization of novel lignans. Altogether, this 1H NMR network approach represents a powerful tool for the study of specialized metabolites in a myriad of contexts relevant to the field of Chemical Ecology