8,972 research outputs found

    Topological properties of P.A. random graphs with edge-step functions

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    In this work we investigate a preferential attachment model whose parameter is a function f:N[0,1]f:\mathbb{N}\to[0,1] that drives the asymptotic proportion between the numbers of vertices and edges of the graph. We investigate topological features of the graphs, proving general bounds for the diameter and the clique number. Our results regarding the diameter are sharp when ff is a regularly varying function at infinity with strictly negative index of regular variation γ-\gamma. For this particular class, we prove a characterization for the diameter that depends only on γ-\gamma. More specifically, we prove that the diameter of such graphs is of order 1/γ1/\gamma with high probability, although its vertex set order goes to infinity polynomially. Sharp results for the diameter for a wide class of slowly varying functions are also obtained. The almost sure convergence for the properly normalized logarithm of the clique number of the graphs generated by slowly varying functions is also proved

    ATP as a presynaptic modulator

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    © 2000 Elsevier Science Inc.There is considerable evidence that ATP acts as a fast transmitter or co-transmitter in autonomic and sensory nerves mostly through activation of ionotropic P2X receptors but also through metabotropic P2Y receptors. By analogy, the observations that ATP is released from stimulated central nervous system (CNS) nerve terminals and that responses to exogenously added ATP can be recorded in central neurons, lead to the proposal that ATP might also be a fast transmitter in the CNS. However, in spite of the robust expression of P2 receptor mRNA and binding to P2 receptors in the CNS, the demonstration of central purinergic transmission has mostly remained elusive. We now review evidence to suggest that ATP may also act presynaptically rather than solely postsynaptically in the nervous system.Fundação Ciência e Tecnologia and European nio

    Inhibition by ATP of hippocampal synaptic transmission requires localized extracellular catabolism by ecto-nucleotidases into adenosine and channeling to adenosine A1 receptors

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    © 1998 Society for NeuroscienceATP analogs substituted in the γ-phosphorus (ATPγS, β, γ-imido-ATP, and β, γ-methylene-ATP) were used to probe the involvement of P2 receptors in the modulation of synaptic transmission in the hippocampus, because their extracellular catabolism was virtually not detected in CA1 slices. ATP and γ-substituted analogs were equipotent to inhibit synaptic transmission in CA1 pyramid synapses (IC50 of 17–22 μM). The inhibitory effect of ATP and γ-phosphorus-substituted ATP analogs (30 μM) was not modified by the P2 receptor antagonist suramin (100 μM), was inhibited by 42–49% by the ecto-5’- nucleotidase inhibitor and α, β-methylene ADP (100 μM), was inhibited by 74–85% by 2 U/ml adenosine deaminase (which converts adenosine into its inactive metabolite-inosine), and was nearly prevented by the adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (10 nM). Stronger support for the involvement of extracellular adenosine formation as a main requirement for the inhibitory effect of ATP and γ-substituted ATP analogs was the observation that an inhibitor of adenosine uptake, dipyridamole (20 μM), potentiated by 92–124% the inhibitory effect of ATP and γ-substituted ATP analogs (10 μM), a potentiation similar to that obtained for 10 μM adenosine (113%). Thus, the present results indicate that inhibition by extracellular ATP of hippocampal synaptic transmission requires localized extracellular catabolism by ectonucleotidases and channeling of the generated adenosine to adenosine A1 receptors.This work was supported by Junta Nacional de Investigação Cientifica e Tecnológica, Praxis XXI, Gulbenkian Foundation, and European Union (BIOMED 2 programme

    Orientação visual espacial e gravidade representacional: a orientação das pistas visuais modula a extrapolação percetual de um alvo em movimento

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    The perceived offset of a moving target is usually displaced forward, in the direction of motion (Representational Momentum), and downwards, in the direction of gravity (Representational Gravity). In what refers to the latter, the meaning of “downward in the direction of gravity” is ill-defined, for it is known that the perceived direction of gravity (“downward”) results from the interaction of vestibular signals, sensitive to the gravito-inertial vector, an aprioristic tendency to assume that it aligns with the body’s main axis (idiotropic vector) and visual cues. The present work aims to disclose what effects visual cues have on Representational Gravity. Participants performed a spatial localization task as well as a Subjective Visual Vertical (SVV) and an Oriented Character Recognition Task (OCHART), with stimuli being presented above a realistic background either aligned with earth’s vertical or tilted rightward or leftward. Outcomes disclosed significant and lawful effects of the orientation of the visual context on spatial localization judgements. Specifically, forward displacement along the target’s motion direction (M-displacement) was bigger for targets moving along the ‘horizontal’ direction implied by the background scene. These trends were furthermore found to be correlated, at an individual level, with the magnitude of SVV, but not of the Perceptual Upright (as measured with OCHART). These findings show that features of the spatial localization judgements specifically index the visually induced spatial orientation, thus offering the prospect to expand available tools for inquiries concerning human spatial orientation, besides clarifying the multisensorial nature and significantly expanding the notion of Representational Gravity.O local de desaparecimento de um objeto em movimento é geralmente percebido como desfasado para diante, na direção do movimento (Momento Representacional), e para baixo, na direção da gravidade (Gravidade Representacional). No que se refere a esse último, o termo “para baixo na direção da gravidade” é ambíguo, pois está estabelecido que a direção percebida da gravidade (“para baixo”) resulta de uma interação entre sinais vestibulares, sensíveis ao vector gravito-inercial, uma tendência a priori para assumir que essa se alinha com o eixo principal do corpo (vector idiotrópico) e pistas visuais. Assim, este trabalho procura perceber quais os efeitos que pistas visuais têm sobre a Gravidade Representacional. Os participantes realizaram três tarefas. Uma tarefa de localização espacial, outra de perceção da direção vertical subjetiva (SVV) e ainda uma tarefa de reconhecimento da orientação de caracteres (OCHART). Os estímulos foram apresentados sobre um fundo realista e rico em pistas visuais, alinhado na direção da gravidade ou inclinado para a esquerda/direita. Os resultados indicam que pistas visuais têm um efeito significativo na perceção da localização espacial. A saber, o desfasamento no sentido do movimento do alvo (Desfasamento-M) foi superior para alvos que se deslocaram na direção ‘’horizontal’’ imposta pelo fundo. Este padrão, adicionalmente, correlacionou-se com a magnitude da vertical visual subjetiva, mas não com a orientação ‘vertical’ percebida (medida pela OCHART). Estes resultados mostram que os juízos de localização espacial são modulados pela orientação espacial induzida visualmente, oferecendo assim uma base teórico-empírica para expandir estudos sobre a orientação espacial, além de clarificar a natureza multissensorial da Gravidade Representacional.Mestrado em Psicologia da Saúde e Reabilitação Neuropsicológic

    Safe API Evolution in a Microservice Architecture with a Pluggable and Transactionless Solution

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    In contrast to monolithic system designs, microservice architectures provide greater scala- bility, availability, and delivery by separating the elements of a large project into indepen- dent entities linked through a network of services. Because services are tied to one another via their interfaces, they can only evolve separately if their contracts remain consistent. There is a scarcity of mechanisms for safely evolving and discontinuing functionalities of services. In monolithic system design’s, changing the definition of an element can be accom- plished quickly with the aid of developer tools (such as IDE refactoring toolkits). In distributed systems there is a lack of comparable tools, developers are left with the burden of manually tracking down and resolving problems caused by uncontrolled updates. To ensure that microservices are working properly the general approach is to validate their behaviour through empirical tests. This thesis aims to supplement the conventional approach by providing mechanisms that support the automatic validation of deployment operations, and the evolution of mi- croservice interfaces. It ́s presented a microservice management system that verifies the safety of modifications to service interfaces and that enables the evolution of service con- tracts without impacting consumer services. The system use runtime-generated proxies, that dynamically convert the data sent between services to the format expected by static code, thereby relieving the developer of the need to manually adapt existing services.Em contraste com sistemas tradicionais monoliticos, as arquiteturas de microsserviços permitem grande escalabilidade, disponibilidade e capacidade de entrega, separando os elementos de um grande projeto em entidades independentes ligadas através de uma rede serviços. Como os serviços estão ligados uns aos outros através das suas interfaces, só podem evoluir separadamente se os seus contratos se mantiverem consistentes. Existe uma escassez de mecanismos para evoluir e descontinuar as funcionalidades dos serviços em segurança. Nos sistemas tradicionais monoliticos, a alteração da definição de um elemento pode ser realizada rapidamente com a ajuda de ferramentas automatizadas (tais como kits de ferramentas de refactoring IDE). Em sistemas distribuídos, existe falta de ferramentas comparáveis, os programadores ficam normalmente sobrecarregados com a resolução ma- nual de problemas causados por atualizações e pela validação do correcto funcionamento do sistema através de testes empíricos. O trabalho desenvolvido nesta tese procura complementar a abordagem convencional, fornecendo mecanismos que suportam a validação das operações de deployment. É apre- sentado um sistema de gestão de microsserviços que verifica a segurança das modificações das interfaces de serviço e a evolução dos contratos. A abordagem utiliza proxies, que convertem dinamicamente os dados enviados entre serviços ao formato esperado pelo código de serviço estático, minimizando a intervenção manual do programador

    Impact of the Covid-19 pandemic on cause-related marketing

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    The COVID-19 pandemic sprouted a surge of borderless societal modifications. As individuals felt their lifestyles suddenly arriving to a halt, businesses did as well. However, consequential of corporations’ involvement in socially responsible practices growth, individuals have sprinkled these with added responsibility to take action in easing the effects of the pandemic. This research addresses the socially responsible corporate practice of Cause-Related Marketing and seeks to fill the gaps in the literature by uncovering if or how a cause’s temporal orientation (immediate vs ongoing) sways consumers’ behaviours, taking into consideration the involving society’s current pandemic standpoint. In order to study the detected gaps, two distinct causes: Banco Alimentar Contra a Fome (immediate cause) and Liga Portuguesa Contra o Cancro (ongoing cause); are assessed. Relying on the use of partial least squares structural equation modelling and a total of 300 consumers’ answers, a myriad of deductions are extracted. Results show that there will be an impact on Cause-Related Marketing, since consumers’ behaviour are set to change as a consequence of the COVID-19 pandemic. Additionally, it is found a contrast in consumers’ responses to a Cause-Related Marketing campaign depending on the temporal orientation of the cause. For instance, in an ongoing cause the higher the brand-cause fit the higher the attitudes toward the Cause-Related Marketing campaign will be, and the higher the cognitive flexibility of their consumers the higher the impact on purchase intentions.A pandemia de COVID-19 gerou uma onda de modificações sociais sem fronteiras. À medida que os indivíduos sentiam que o seu estilo de vida abrandava repentinamente, as empresas também o sentiram. No entanto, como consequência do crescente envolvimento das corporações nas práticas socialmente responsáveis, os indivíduos pressionaram-nas para tomarem medidas de modo a aliviar os efeitos da pandemia. Esta pesquisa aborda a prática corporativa de Marketing de Causas e procura preencher as lacunas encontradas na literatura propondo a descoberta de como, ou se, a orientação temporal de uma causa (imediata vs contínua) influencia o comportamento dos consumidores; tendo em consideração a pandemia em que a sociedade se encontra envolvida, atualmente. De modo a estudar as lacunas detectadas, duas causas distintas: Banco Alimentar Contra a Fome (causa imediata) e a Liga Portuguesa Contra o Cancro (causa contínua); são analisadas. Tendo por base o uso de modelagem de equação estrutural partial least squares e um total de 300 respostas de consumidores, várias deduções são extraídas. Os resultados demonstram que haverá um impacto da pandemia no Marketing de Causas, uma vez que o comportamento dos consumidores se alterou. Além disso, é encontrado um contraste nas respostas dos consumidores a uma campanha de Marketing de Causas, dependendo da orientação temporal da causa. Por exemplo, numa causa contínua, quanto maior o fit entre a marca e a causa, maiores serão as atitudes em relação à campanha de Marketing de Causas, e quanto maior a flexibilidade cognitiva dos consumidores, maior será o impacto nas intenções de compra

    Terrorism and religion : brazilian media’s image of religion inspired terrorism

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    My research question was: How do Brazilian Media Portray Religious Terrorism? The aim of this thesis was to analyse Brazilian media’s articles and speeches related to the theme of religious terrorism and bring the findings more accessible to Finland and Europe. I collected several articles from Brazilian Internet news websites as well as few articles from foreign websites and analysed those articles using a mixed method of qualitative discourse analysis and content analysis. Discrepancies were found between Brazilian government’s official position of Brazil being a terrorist free country while Wikileaks revealed that there are individuals acting and behaving like terrorists in Brazil. When arrested, those individuals were charged with other charges than terrorism, possibly to not attract media’s attention to them. The articles written in Informal style varied from non emotional to strong emotional connoted, figures of speech such as metaphors metonymies, accismus were richly used. Towards the end, Arab culture in Brazil as well as fundamentalism and extremism religion movements in Islam were used as background to why Brazilian press portrays such image of terrorism. Brazilian journalists were divided; some alarmists warning of a near terrorism danger while others commenting that this is non sense. Brazil has a clear historical peaceful co-existence between different religious groups and has been so far not affected by bombings or anti-immigration feelings seen in other countries, making Brazil a good role model of integration and tolerance
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