Complementarities, Costly Investment and Multiple Equilibria in a One-Sector Endogenous Growth Model

In this paper we develop a multiple equilibria one-sector R&D-based growth model, in which the key aspects are the assumption of complementarities between capital goods in the production function and the assumption of costly investment in capital. This second assumption is new to the R&D-based literature. The equilibrium solutions are obtained when the Preferences curve, which mirrors consumers’ savings decisions, and the Technology curve, which represents equilibria on the production side, cross. The combination of the two key assumptions produces a non-linear Technology curve, which consequently crosses the Preferences curve more than once, thus generating multiple equilibria. A numerical solutions exercise obtains two equilibria. Application of the stability under learning criterion allows for the identification of the two equilibria as stable. Expectations can lead the economy to either the equilibrium characterised by high-growth and high-interest rates, or to the equilibrium characterised by low-growth and low-interest rates. Hence, with this model, we wish to contribute to endogenous growth literature by providing a mechanism to explain how an economy can experience multiple equilibria situations.Growth, R&D, complementarities, costly investment, multiple equilibria.

A Nonscale Growth Model with R&D and Human Capital Accumulation

This paper presents an endogenous growth model that includes research and development and human capital accumulation. The model’s specification builds on the R&D-based structure of Romer’s [1990] model and introduces two functions: (1) A specification for the production of new designs that assumes no externalities and no inventions before time zero; and (2) A specification for the accumulation of human capital technically similar to that in Lucas [1988]. The model displays two main results. The first is that it eliminates the scale-effects prediction which is common to most R&D-based growth models, but which is not empirically supported. Secondly, the model offers a new prediction that growth depends positively on the ratio of final-good workers to researchers. Thus the model provides a theoretical explanation as to why developed countries have had rising numbers of researchers but not rising growth rates in the twentieth century.endogenous growth; research and development; human capital accumulation; scale-effects prediction; final-good workers to researchers ratio.

A nonscale growth model with R&D and human capital accumulation

This paper aims to contribute to the new growth theory with a model in which the engine of growth is human capital growth. Building on Romer's [1990] model, two new functions are introduced: (1) a specification for the production of new designs that assumes no externalities and no inventions before time zero; and (2) A specification for the accumulation of human capital technically similar to that in Lucas [1988]. As opposed to Romer's model, the scale-effects prediction is eliminated because technological growth does not depend on the number of researchers, but instead on the rate of growth of human capital. Moreover, the model introduced carries a new prediction: Growth depends positively on the ratio of final-good workers to researchers

Imagem Pública, Marketing e Comunicação Institucional: Uma Abordagem Sociológica de Três Conceitos Empresariais

Este artigo propõe uma reflexão sociológica e crítica sobre conceitos/práticas habitualmente tratados no âmbito das ciências empresariais – ‘imagem pública’, ‘marketing’ e ‘comunicação institucional’ – e que dizem respeito à gestão das relações que as organizações mantêm com os seus públicos. A análise desenvolvida questiona as dicotomias convencionais de público/privado, economia/cultura, material/simbólico e empresarial/institucional, procurando compreender como estes campos são transformados através da reflexividade generalizada – cognitiva e estética – das sociedades contemporâneas. A questão central do argumento que se segue é a relação cada vez mais intensa, no cenário actual, entre a gestão de relações económicas e a gestão de relações simbólicas e culturais. A questão de partida é a reconsideração da dualidade entre ciências sociais e ciências empresariais no quadro dos estudos sobre comunicação. Seguidamente, aqueles três conceitos serão pensados, do ponto de vista sociológico:as imagens públicas como representações da sociedade espectadora, o marketing como técnica de gestão do social e, mais especificamente, a comunicação institucional como gestão empresarial dos mercados simbólicos

Complementarities, costly investment and multiple equilibria in a one-sector endogenous growth model

In this paper we develop a multiple equilibria one-sector R&D-based growth model, in which the key aspects are the assumption of complementarities between capital goods in the production function and the assumption of costly investment in capital. This second assumption is new to the R&D-based literature. The equilibrium solutions are obtained when the Preferences curve, which mirrors consumers’ savings decisions, and the Technology curve, which represents equilibria on the production side, cross. The combination of the two key assumptions produces a non-linear Technology curve, which consequently crosses the Preferences curve more than once, thus generating multiple equilibria. A numerical solutions exercise obtains two equilibria. Application of the stability under learning criterion allows for the identification of the two equilibria as stable. Expectations can lead the economy to either the equilibrium characterised by high-growth and high-interest rates, or to the equilibrium characterised by low-growth and low-interest rates. Hence, with this model, we wish to contribute to endogenous growth literature by providing a mechanism to explain how an economy can experience multiple equilibria situations

Media e sua viabilização pelo mercado: uma reflexão crítica sobre audiências e públicos

Este breve artigo dá conta de algumas reflexões sobre a viabilização financeira de media audiovisuais: televisão e rádio. Tem particularmente em vista projectos orientados por valores não mercantis: valores sociais, culturais ou artísticos. Num primeiro momento, questiona-se criticamente o conceito de ‘audiència’. Num segundo momento, sugere-se que os receptores de media sejam encarados, não como um conjunto de indivíduos atomizados e passivos, mas como públicos com capacidade de acção na viabilização dos projectos mediáticos que lhes interessam. Num primeiro momento colocaremos um conjunto de questões com as quais pretendemos reflectir sobre os limites e deficiências do conceito que está na base do sistema de financiamento de rádio e televisão preponderante nos nossos dias. Isto é, questionaremos criticamente o conceito de "audiências". Num segundo momento sugerimos a necessidade de os "receptores" de media serem encarados, não como um conjunto de indivíduos atomizados e passivos, mas como públicos com capacidade de acção na viabilização dos projectos mediáticos que lhes interessem. A questão da viabilização dos projectos é a da viabilização pelo mercado, pelo que não consideraremos a questão dos financiamentos estatais, com a qual seríamos remetidos para outras problemáticas - do papel do Estado em relação à cultura, da definição de serviço público de televisão ou rádio, etc. (ainda que estas problemáticas estejam em relação com as que aqui colocamos)

Social capital, innovation and economic growth

Multidisciplinary innovation is the engine of growth of an increasing number of economies. Innovation output depends increasingly on information sharing and cooperation between creative agents. Sharing and cooperation requires the existence of generalised trust. Social capital consists of trust and trust-based networks. Our main goal is to illustrate theoretically the importance of social capital to the growth of an innovation economy.COMPETE, QREN, FEDER, Fundação para a Ciência e a Tecnologia (FCT

A Nonscale growth model with R&D and human capital accumulation

This paper presents an endogenous growth model that includes research and development and human capital accumulation. The model’s specification builds on the R&D-based structure of Romer’s [1990] model and introduces two functions: (1) A specification for the production of new designs that assumes no externalities and no inventions before time zero; and (2) A specification for the accumulation of human capital technically similar to that in Lucas [1988]. The model displays two main results. The first is that it eliminates the scale-effects prediction which is common to most R&D-based growth models, but which is not empirically supported. Secondly, the model offers a new prediction that growth depends positively on the ratio of final-good workers to researchers. Thus the model provides a theoretical explanation as to why developed countries have had rising numbers of researchers but not rising growth rates in the twentieth century.Fundação para a Ciência e Tecnologia - (FCT)

Endogenous Growth: Analytical Review of its Generating Mechanisms

This paper consists of an analytical review of the most relevant endogenous growth models. The objective of this literature review is to discuss analytically and understand, in an integrated form, the main mechanisms, identified in the existing literature, that generate endogenous growth. Endogenous or new growth theory has, so far, produced three main types of mechanisms through which endogenous sustained positive economic growth is made possible. One strategy brings a theory of innovations or R&D into the growth model. In this type of model, endogenously determined technological progress is the engine of economic growth. The second mechanism delivers sustained positive growth through the introduction of an endogenously determined accumulation of human capital. In this kind of model, the source of long-run per-capita growth is human capital accumulation. And a third way to obtain endogenous growth is simply to abandon one of the standard assumptions of the neoclassical model, more precisely the assumption of diminishing returns to capital.non-diminishing returns to capital; endogenous growth; research and development (R&D); human capital accumulation; Inada conditions.

Formação de Nanomaterial-corona específica : avanços para o modo de ação de NMS

The growing use of nanomaterials (NMs) in a wide variety of fields is due to the better and innovative properties that they can offer to, e.g., the end-use industry or biomedicine. The release of NMs into the environment during their life-cycle is an actual scenario. Reaching the environment, the NMs will interact with the organisms, but despite the growing efforts to provide conclusive results on the safety of NMs, their impact is still poorly understood, particularly in the terrestrial compartment. There are many knowledge gaps that need to be covered to better understand the mechanisms that drive NMs toxicity, hence this thesis aims to increase the knowledge on the effects of selected NMs in soil invertebrates. Understanding NMs mode of action is key to safer-by-design strategies that will contribute to improve nanotechnology sustainability. Effect assessment of NMs was done at several levels of biological organization, covering different endpoints, which can be integrated in order to understand the toxicity mechanisms. Further, long-term and multigenerational effects were also considered, as they are likely scenarios for NMs exposure. Selected NMs - silver (Ag), tungsten carbide cobalt (WCCo) and copper oxide (CuO) case study (using different surface modifications), along with the corresponding salt forms, were tested at different levels: molecular (oxidative stress and genotoxicity) and organism (survival and reproduction). The standard soil invertebrates Enchytraeus crypticus and Eiseina fetida were used for in vivo and in vitro exposures, respectively. Sub-lethal concentrations of Ag NMs induced distinct and later biochemical effects (oxidative stress and genotoxicity) in E. crypticus compared to the nonnano form (AgNO3). While different responses point to nano-specific effects, possible dissolution of Ag NMs and consequent ion-driven toxicity can also be occurring. WCCo NMs impaired reproduction in E. crypticus, at a higher extent compared to CoCl2 (assuming similar Co concentrations). The lower Co concentrations in the soil:water interface and lower uptake in WCCo exposed organisms suggest that toxicity resulted from a combined effect between WC and Co. Multigenerational exposure did not increase toxicity in terms of survival and reproduction, in spite of Co internalization. Monitoring of Co body burden pointed to Co elimination and storage as the detoxifying strategies in WCCo and CoCl2 exposed organisms, respectively. CuO NMs did not decrease viability of Eisenia fetida’s immune cells, either in the pristine form or with different surface modifications. The interaction with the biomolecules present in the coelomic fluid may have led to the formation of a native corona that interfered with the toxic potential, independently of the surface modification, but the impact of such interaction is unclear. Some technical aspects need further optimization due to the possibility that the effects could have been underestimated, but this constitutes a promising test system for in vitro testing battery.A crescente utilização de nanomateriais (NMs) numa grande variedade de setores é devida às melhores e mais inovadoras propriedades que estes podem oferecer, por exemplo, à indústria de uso final ou à biomedicina. A libertação de NMs no ambiente durante o seu ciclo de vida é um cenário actual. Ao entrarem no ambiente, os NMs irão interagir com os organismos, e apesar dos crescentes esforços para fornecer resultados conclusivos sobre a segurança dos NMs, o seu impacto ainda é pouco conhecido, particularmente no compartimento terrestre. Existem várias lacunas no conhecimento que necessitam de ser preenchidas de forma a entender melhor os mecanismos que levam à toxicidade dos NMs; assim, esta tese pretende aumentar o conhecimento dos efeitos de NMs selecionados em invertebrados de solo. Perceber o mecanismo de acção dos NMs é a chave para estratégias safer-bydesign, fundamentais para melhorar a sustentabilidade da nanotecnologia. A avaliação dos efeitos dos NMs foi realizada a vários níveis de organização biológica, cobrindo diferentes endpoints, que, sendo integrados, permitem perceber os mecanismos de toxicidade. Os efeitos a longo-prazo e multigeneracionais foram também considerados, uma vez que são possíveis cenários de exposição aos NMs. Os NMs selecionados – prata (Ag), liga de carboneto de tungsténio-cobalto (WCCo) e o caso estudo de óxido de cobre (CuO) (usando diferentes modificações da superfície), juntamente com os correspondentes sais, foram usados a diferentes níveis: molecular (stress oxidativo e genotoxicidade) e do organismo (sobrevivência e reprodução). Os invertebrados modelo de solo Enchytraeus crypticus e Eisenia fetida foram usados em exposições in vivo e in vitro, respectivamente. Concentrações sub-letais de Ag NMs induziram efeitos bioquímicos (de stress oxidativo e genotoxicidade) em E. crypticus, distintos e mais tardios comparados com a forma não-nano (AgNO3). Enquanto diferentes respostas apontam para efeitos nano-específicos, a possível dissolução de Ag NMs e consequente toxicidade induzida pelos iões também pode ocorrer. WCCo NMs comprometeram a reprodução de E. crypticus de forma superior comparado com CoCl2 (assumindo concentrações de Co semelhantes). Menores concentrações de Co na interface solo-água e a menor internalização de Co nos organismos expostos a WCCo, sugere que a toxicidade resulta do efeito combinado entre WC e Co. Apesar da internalização de Co, a exposição multigeneracional não aumentou a toxicidade em termos de sobrevivência e reprodução. A monitorização da quantidade de Co nos organismos aponta para a eliminação e armazenamento como estratégias de detoxificação nos organismos expostos a WCCo NMs e CoCl2, respectivamente. Os CuO NMs não diminuíram a viabilidade das células dos sistema imunitário de Eisenia fetida, quer na forma pristina ou com diferentes modificações da superfície. A interacção com as biomoléculas presentes no fluido celómico terá levado à formação de uma corona nativa que interferiu com o potencial de toxicidade, independentemente da modificação da superfície, mas o impacto dessa interação não é claro. Alguns aspectos técnicos necessitam de otimização devido à possibilidade dos efeitos terem sido subestimados, mas este constitui um sistema de teste promissor para a bateria de testes in vitro.Programa Doutoral em Biologi