3,656 research outputs found

    Validation of the online political engagement scale in a British population survey

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    Over the last decade, there has been an ever increasing number of citizens using online media to participate in and engage with politics. Social media sites and online blogs have enabled new opportunities for interactive and user-centered political experiences. Currently, there is a general scarcity of psychometrically validated and standardized instruments that assess politically-related constructs (e.g., political engagement, political participation) in the field of political sciences. The main aim of the present study was to develop a standardized psychometric tool to assess online political engagement among the general population that is valid and reliable. The present study examined the psychometric properties of a 7-item Online Political Engagement Scale (OPEnS) that assesses various online political actions people engage with during election campaigns. To develop the scale, data from the 2010 British Election Survey were used, and a total of 3,075 people participated in an online survey, post-election. The main findings obtained in the present study supported the undimensionality of the online political engagement construct given the results obtained from exploratory and confirmatory factor analyses. The OPEnS appears to be a valid and reliable instrument for assessing this phenomenon, and may be useful in studies investigating newer patterns of online political engagement and disengagement

    Barrierless procedure for substitutionally doping graphene sheets with boron atoms: ab initio calculations

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    Using ab initio methods, we propose a simple and effective way to substitutionally dope graphene sheets with Boron. The method consists of selectively exposing each side of the graphene sheet to different elements. We first expose one side of the membrane to Boron, while the other side is exposed to Nitrogen. Proceeding this way, the B atoms will be spontaneously incorporated into the graphene membrane, without any activation barrier. In a second step, the system should be exposed to a H-rich environment, that will remove the CN radical from the layer and form HCN, leading to a perfect substitutional doping.Comment: Accepted Physical Review

    Optimization Of A Large Scale Industrial Reactor Towards Tailor Made Polymers Using Genetic Algorithm

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    Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This paper presents a computational procedure for producing tailor made polymer resins, satisfying customers' needs while operating with maximum profit. The case study is an industrial large-scale polymerization reactor. The molecular properties considered are melt index (MI), which measures the molecular weight distribution, and stress exponent (SE), which is related to polydispersity. An economic objective function is associated to a deterministic mathematical model and the resulting optimization problem is solved by genetic algorithm (GA), a stochastic method. The GA parameters for both binary and real codifications are tuned by means of the design of experiments. Attempting to achieve the global optimum, a hybrid method, which introduces process knowledge into GA random initial population, is proposed. The binary codification performs better than the real GA, especially with hybridization. Results show that the GA can satisfactorily predict tailor made polymer resins with profits up to 25% higher than the industrial practice.14259267CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)CNPq (Conselho Nacional de Pesquisa)FAPESB (Fundacao de Amaro a Pesquisa do Estado da Bahia)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

    Validation of the Online Political Engagement Scale in a British population survey

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    Summary. Over the last decade, an ever increasing number of citizens have been using online media to participatein and engage with politics. Social media sites and online blogs have enabled new opportunities for interactive,user-centered political experiences. Currently, there is a general scarcity of psychometrically validated and standardizedinstruments that assess politically-related constructs (e.g., political engagement, political participation) in thefield of political science. The main aim of the present study was to develop a valid, reliable, standardized psychometrictool to assess online political engagement among the general population. The present study examined thepsychometric properties of a seven-item Online Political Engagement Scale (OPEnS) that assesses a range of politicalactions people engage in online during election campaigns. To develop the scale, data from the 2010 BritishElection Survey were used, as well as information collected from a total of 3,075 people who participated in apost-election online survey. The main findings obtained in the present study supported the unidimensional natureof the online political engagement construct given the results obtained from exploratory and confirmatory factoranalyses. The OPEnS appears to be a valid and reliable instrument for assessing this phenomenon, and it may beuseful in studies investigating newer patterns of online political engagement and disengagement.Resum. Durant l’última dècada, un nombre cada vegada més gran de ciutadans han estat utilitzant els mitjansde comunicació en línia per participar i comprometre’s amb la política. Les xarxes socials i blocs en línia hanpermès noves oportunitats per a experiències polítiques interactius, centrats en l’usuari. Actualment, hi ha unaescassetat general d’instruments psicomètrics estandarditzats i validats que avaluen constructes relacionats ambla política (per exemple, el compromís polític, participació política) en el camp de la ciència política. L’objectiuprincipal d’aquest estudi era desenvolupar una eina vàlida, fiable i estandarditzada per avaluar la participaciópolítica en línia entre la població general. El present estudi va examinar les propietats psicomètriques d’una escalade set items, l’Escala de Compromís Polític en línia (Online Political Engagement Scale, OPEnS) que avalua unseguit d’accions polítiques en les que les persones s’involucren en línia durant les campanyes electorals. Per desenvoluparl’escala, es van utilitzar les dades de l’Enquesta d’Elecció Britànica de 2010, així com la informació recopiladad’un total de 3.075 persones que van participar en una enquesta en línia després de les eleccions. Elsprincipals resultats obtinguts en el present estudi van recolzar la naturalesa unidimensional del constructe decompromís polític en línia, donat els resultats obtinguts de les anàlisis factorial exploratòria i confirmatòria.L’OPEnS sembla ser un instrument vàlid i fiable per avaluar aquest fenomen, i pot ser útil en estudis de recerca denous patrons de participació i no participació política en línia

    Thermoelectrical regulation of microinjection moulds

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    Microinjection is one of the major replication techniques for producing low cost micro parts. The small scale of the microinjection processes presents different challenges from those usually encountered in conventional injection moulding. One particular aspect, very important for part quality, is mould temperature control. In conventional injection moulding, the temperature control system is set to a fixed value during the injection cycle. In microinjection moulding such behaviour is not acceptable, which as lead to the development of “active” control temperature of the mould named “variotherm” systems. In the present paper a study will be presented for the implementation of thermo electric elements in dynamic temperature control of microinjection moulds and its impact on the process cycle time and part quality
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