9,320 research outputs found

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

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    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.

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

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    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.

    Postural patterns in the first year of life: contributions of maternal physical activity in the pregnancy period

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    BACKGROUND: The study objective was intended to verify whether the practice of maternal physical activity during the pregnancy period could be assumed as a contribution to the acquisition of postural patterns in the child during its first year of life. METHODS: A transversal and descriptive study was carried where we recorded the developments observed in a sample of 80 Portuguese children, according to the habits and type of physical activity of the mothers. Statistical descriptive and inferential test were performed. RESULTS: The results were clearly positive in terms of temporal gains of neck tonic control, and also in the acquisition of an erect position. CONCLUSIONS: Despite the average values are not statistical significant we have observed indicators that the maternal physical activity during pregnancy apparently is a factor that can favor the child’s motor development during their first year of life, particularly in the acquisition of postural patterns.info:eu-repo/semantics/publishedVersio

    Management accounting and power: A contested relationship

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    This paper is structured in two parts. In the first part we undertake a brief discussion on the concept of power and we explore the way this concept has been regarded in several strands of literature on management accounting – the conventional, the contingency, the pluralist, the interpretive, the critical and the post-structuralist. Some of these strands – for instance, the pluralist, the critical and the post-structuralist – explicitly recognise the importance of (some conception of) power in their approach to management accounting in society and organisations. Other approaches are less explicit in that recognition or simply overlook/reject it. The second part of the paper takes sides, departing from the idea that there is a relationship between management accounting and power and proposes a framework for conceptualising that relationship. This framework attempts to bring together different dimensions/conceptions of power, and is proposed as a way to study management accounting and its change within organisations.power, management accounting, change, circuits of power

    Using a coastal storm hazard index to assess storm impacts in Lisbon

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    Coastal areas are among the most dynamic earth systems as they are exposed to powerful agents. Near-shore wave energy is one of the most important triggering factors for erosion and flooding and is often neglected for severe infrastructure damaging, property losses and loss of life. These consequences are amplified with high population density and heavy infrastructure implantation as it happens in Lisbon (Portugal). In this context, it is of great importance for coastal stakeholders, decision-makers and civil protection entities to estimate precisely the spatial distribution of storm hazard for prevention and mitigation purposes, as well as to design adjusted answers for calamity responses. We apply a coastal storm hazard index (CSHI) considering triggering and conditioning variables involved in the effects of an extreme storm, namely: 100-year return period of SWAN modelled Hs, and its spatial distribution across the study area, land use, number of buildings, height, slope, geology, geomorphology, erosion/ accretion rates, width of the systems, exposure of the coastline, bathymetry and legally protected areas. The variables were weighted according to a hierarchical analysis process and classified into five classes of exposure. A validation process was then implemented by comparing the occurrences identified in the last two decades newspapers and the storm hazard classification, showing a satisfactory validation results. The results show a classified storm hazard map that identifies the most and the less exposed areas. High values of CSHI occur in areas with excessive human pressure, low heights sandy systems with significant costal erosion rates. The main type of consequences identified are associated with inland flooding and erosion, resulting in the destruction of coastal protection infrastructures, and population displacement leading to great economic and social impacts and loss of life.info:eu-repo/semantics/publishedVersio

    The role of the abandonment option in strategic capital allocation: a review of selected literature

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    We review the most relevant contributions to the abandonment option since the late 1960s. We begin by approaching the contributions to the literature before the emergence of the real options approach to capital investment decisions, and thereafter, under a consistent real options approach, highlighting the interactions between the option to abandon and other types of options. We then identify the methodologies adopted, and the business sectors/ types of investment projects where the abandonment option is more frequently studied. We also debate the strategic role of the abandonment solution in corporate divestitures and under a game-theoretical approach. Finally, we present some concluding remarks and identify how certain gaps found in the literature may constitute opportunities for future research

    A Growth Model for the Quadruple Helix Innovation Theory

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    We propose a theoretical growth model with which to frame analytically the Quadruple Helix Innovation Theory (QHIT). The aim is to emphasise the investment in innovation transmission mechanisms in terms of economic growth and productivity gains, in one-high-technology sector, by stressing the role played by the helices of the Quadruple Helix Innovation Model: Academiaand Technological Infrastructures, Firms of Innovation, Government and Civil Society. In the existing literature, the relationship between the helices and respective impacts on economic growth does not appear clear. Results are fragiledue to data weakness and the inexistence of a theoretical framework to specify the relationship between the helices. Hence our motivation for providing the QHIT with a theoretical growth model. Our intent is to model the importance of emerging, dynamically adaptive, and transdisciplinary knowledge and innovation ecosystems to economic growth. We .nd that higher economic growth rate is obtained as a result of an increase in synergies and complementarities between different productive units, or an incease in productive government expenditure.Economic Growth; Quadruple Helix Innovation Model; Innovation Ecosystems.

    Seamless Multimodal Biometrics for Continuous Personalised Wellbeing Monitoring

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    Artificially intelligent perception is increasingly present in the lives of every one of us. Vehicles are no exception, (...) In the near future, pattern recognition will have an even stronger role in vehicles, as self-driving cars will require automated ways to understand what is happening around (and within) them and act accordingly. (...) This doctoral work focused on advancing in-vehicle sensing through the research of novel computer vision and pattern recognition methodologies for both biometrics and wellbeing monitoring. The main focus has been on electrocardiogram (ECG) biometrics, a trait well-known for its potential for seamless driver monitoring. Major efforts were devoted to achieving improved performance in identification and identity verification in off-the-person scenarios, well-known for increased noise and variability. Here, end-to-end deep learning ECG biometric solutions were proposed and important topics were addressed such as cross-database and long-term performance, waveform relevance through explainability, and interlead conversion. Face biometrics, a natural complement to the ECG in seamless unconstrained scenarios, was also studied in this work. The open challenges of masked face recognition and interpretability in biometrics were tackled in an effort to evolve towards algorithms that are more transparent, trustworthy, and robust to significant occlusions. Within the topic of wellbeing monitoring, improved solutions to multimodal emotion recognition in groups of people and activity/violence recognition in in-vehicle scenarios were proposed. At last, we also proposed a novel way to learn template security within end-to-end models, dismissing additional separate encryption processes, and a self-supervised learning approach tailored to sequential data, in order to ensure data security and optimal performance. (...)Comment: Doctoral thesis presented and approved on the 21st of December 2022 to the University of Port
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