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- Essays on public debt, growth and development in AfricaPublication . Veiga, José Augusto Lopes da; Sequeira, Tiago Miguel Guterres Neves; Lopes, Alexandra Maria Nascimento FerreiraThis thesis is entitled “Essays on Public Debt, Growth and Development in Africa” and consists of a set of four essays, three of which are empirical. The first essay provides a literature survey on public debt and economic growth, specially focused on Africa. Since the beginning of the 1990s, public debt has been a real barrier to the economic growth of African economies and has since become part of the agenda and concern of policy makers, economists and researchers. A considerable number of theoretical and empirical studies have been produced over decades, addressing the impact of public debt on the economic growth of these countries. The results are consensual and point generally to an inverse relationship between the two variables i.e. public debt negatively affects economic growth from a given level. Krugman (1988) and Sachs (1989) agree that high levels of public debt mitigate the economic growth of developing countries through investment. This position is further corroborated by Mbale (2013) who referring to African countries argues that public debt crowds out credit to the private sector and constitutes a barrier to capital accumulation and private sector growth. Buchanan (1958) and Modigliani (1961) also share the view that in addition to the crowding out effect, the increase in public debt positively affects the long-term interest rate. Generally, the increase in public debt negatively affects economic growth. Fosu (1996) Irons and Bivens (2010) are decisive in concluding that high debt levels jeopardize economic growth, a position shared by Ezeabasili et al (2011), Escobar and Mallick (2013) and Zouhaier and Fatma (2014). Regarding the impact of fiscal policy on the economic growth of African countries, Devarajan et al. (1996) consider, after empirical analysis, that an increase in public spending has a positive and significant impact on economic growth. Nurudeen and Usman (2010) argue that an increase in public spending is not immediately converted into economic growth, whereas Nworji et al. (2012) show that current and capital expenditures do not have a significant negative impact on Nigeria's economic growth. This view is supported by Engen and Skinner (1997) who concluded that public expenditure and the tax burden negatively and sharply affect economic growth. Babadola and Aminu (2011) provide complementary evidence and recommend that increased public spending on health and education should promote growth. The survey also highlights the inverse relationship between economic growth and government debt, compounded by the problem of debt overhang, preventing these countries from leveraging their economies. Additionally, the literature on the relationship between public deficits and economic growth is also not consensual. In fact, although the economic theory postulates that fiscal deficit contributes inevitably to debt accumulation, which through debt overhang affects negatively economic growth, there are other strings of economic thoughts that advocate that African countries would not reach economic growth without increasing debt. The second essay is empirical and analyzes the implications of public debt on economic growth and inflation in a group of 52 African economies between 1950 and 2012. The overall analysis was focused on the relationship between the limits of public debt as a percentage of the GDP, economic growth, and inflation. African economies achieve their highest performance in terms of average rates of economic growth (6.39%), while the limits of public debt as a percentage of the GDP are in the second intervals (30 - 60%) with an average inflation rate of 8.17%. From this limit, any increase in public debt is converted into a reduction of the average growth rates of economies and into an increase in average inflation rates. The findings show, unequivocally, that there is an inverse relationship between these two macroeconomic variables, depending on the levels of indebtedness. Briefly, the analysis concludes that the highest average growth rates are achieved when the public debt is in the second interval. When this ratio is situated in the third interval the average rates of economic growth suffer a drop of 1.32 percentage points and 1.64 percentage points when this ratio exceeds 90%. These results are much lower than those found by Reinhart and Rogoff in the essay “Growth in Time of Debt”, for which an amount of debt equivalent to 60% of GDP causes a drop in the annual growth rate of around 2 percentage points. The third essay empirically assesses the traditional determinants of economic growth in African economies over the period 1950 to 2012, using growth regression techniques in which the explanatory variables are: public debt per capita, investment ratio, government ratio, capital stock per capita, and the Human Capital Index. The method used takes into account observed and unobserved heterogeneity. The regression results show strong evidence of a positive impact of the growth rate of capital stock to economic growth of African countries. The growth rate of the government to GDP ratio is also important in all but one of the regressions in which appears, and its growth is harmful for economic growth. Human capital has a positive relationship with economic growth in regressions that don’t include public debt. However, the cross country impact of these two variables on the growth rate of the economies (positive to some and negative to others) is not uniform, so that appropriate policies for one country may be seriously misguided in another. Concerning public debt, we found that it is not significant and therefore it has no impact on the economic growth of African countries. The growth rate of real GDP per capita also depends (negatively) on its past value, i.e., the lower the real GDP per capita the higher will be its growth rate. We have also tested two proxies for institutions, which did not deliver significant results. The software used for the regressions is STATA, version 13. The fourth essay is devoted to an exploratory analysis of the main economic, social and institutional determinants of development in Africa, using a main component analysis for categorical data and cluster analysis and taking into account the years 1996 and 2014 as the oldest and most recent, respectively. This methodology allowed the agglomeration of the African countries into four differentiated clusters, being the countries constituting the clusters of 1996 distinct from those of the year 2014. The results point out to a positive association between the social, economic and institutional determinants of development which is reflected in the fact that countries with better institutional performances also show better indicators of economic and social achievement. The results also draw the attention of policy makers and development strategists to the need for an integrated approach to the development process, in order to achieve greater and more efficient integration of the different development determinants. The software used is IBM-SPSS (Statistical Package for Social Sciences), version 23.0.
- Covilhã y su patrimonio industrial: propuesta de recuperación de la Fábrica VelhaPublication . Silva, Margarida; Ramos Jular, Jorge; Lanzinha, JoãoCovilhã es una pequeña ciudad situada en el interior del Portugal continental. Conocida como la ciudad de la lana y de la nieve, atendiendo a su estructura urbana crece desorganizadamente a lo largo de la ladera sudeste de la Serra da Estrela. [...]
- Improving Grasping Performance by Segmentation of Large Planar SurfacePublication . Lopes, Vasco; Alexandre, LuísGrasping objects is a task that humans do without major concerns. This results from learning and observing other skilled humans doing such task and with previous information, unconsciously, we know how to pick up different types of objects. However, grasping novel objects in unknown positions for a robot is a complex task which encounters many problems, such as the performance rates that are not perfect and the time consumption. In this paper we present a method that complements the state-ofthe- art grasping by removing the largest planar surface of the image of the world before the grasp detector receives them. The proposed method improves the performance rate and is also capable of reducing the time consumption.
- A Influência dos fatores impulsionadores e das barreiras à inovação tecnológica empresarialPublication . Kahilana, Orlando Francisco Líssimo; Madeira, Maria José AguilarA Inovação Tecnológica permite, atualmente, as empresas obterem uma capacidade competitiva no mercado. Através dela criam-se novos modelos da administração pública e privada, capacitando-as para a mudança da sua gestão. A Inovação Tecnológica é considerada como resultado tangível e real da tecnologia, um ganho da ciência no ramo tecnológico. É o processo que possibilita combinar os recursos e as capacidades técnicas, financeiras, comerciais e administrativas, permitindo o lançamento no mercado de novos produtos ou melhoria de processos. Deste modo, as vantagens competitivas passam a depender cada vez mais da capacidade de Inovação Tecnológica, estratégias e metas sustentáveis, ganhando o alinhamento global e o posicionamento da empresa num mercado cada vez mais competitivo. A empresa, também deve deter responsabilidade, a qual se traduz na forma de atuar com ética, garantindo que os produtos, serviços, processos e as respetivas operações sejam seguras para os seres humanos e o meio ambiente. Portanto, as abordagens à Inovação Tecnológica sustentam a necessidade do conhecimento científico, de modo a que se perceba a dinâmica empresarial face esses fatores no mercado. Esta investigação tem como objetivo geral estudar a influência dos fatores impulsionadores e das barreiras na Inovação Tecnológica das empresas portuguesas. Os dados foram obtidos através do Inquérito Comunitário à Inovação 2012 (CIS 2012) sob supervisão do EUROSTAT. Na análise de dados recorreu-se aos modelos de Hurdle e de Regressão Logística. Os resultados obtidos, através de análise empírica efetuada, evidenciam que as grandes empresas são mais inovadoras do que as pequenas e médias empresas. As empresas com maior percentagem de empregados com formação superior, apresentam maior nível de capital humano e tendem a ter um maior número de inovações distintas. As empresas que trabalham para os mercados local e nacional têm um maior desempenho inovador. Em relação à cooperação constatou-se que as empresas que cooperam com parceiros, tais como: clientes, fornecedores e entre outras empresas do grupo tem maior desempenho inovador. As empresas que recebem apoio financeiro público para a inovação de entidades local ou regional e governo central tendem a apresentar um maior número de distintas inovações. Também se constatou que as empresas inovadoras que dão muita importância ao obstáculo ‘falta de procura’ tendem a ter um pior desempenho inovador, ao passo que as empresas que dão muita importância ao obstáculo ‘Custo elevado para aceder a novos mercados’ têm um maior desempenho inovador. Os resultados obtidos, através de análise empírica efetuada, mostram que os fatores internos, externo e os fatores associados as políticas públicas influenciam a Inovação tecnológica das empresas.
- The Influence of Image Normalization in Mammographic Classification with CNNsPublication . Perre, Ana Catarina; Alexandre, Luís; Freire, LuísIn order to improve the performance of Convolutional Neural Networks (CNN) in the classification of mammographic images, many researchers choose to apply a normalization method during the pre-processing stage. In this work, we aim to assess the impact of six different normalization methods in the classification performance of two CNNs. Results allow us to concluded that the effect of image normalization in the performance of the CNNs depends of which network is chosen to make the lesion classification; besides, the normalization method that seems to have the most positive impact is the one that subtracts the image mean and divide it by the corresponding standard deviation (best AUC mean with CNN-F = 0.786 and with Caffe = 0.790; best run AUC result was 0.793 with CNN-F and 0.791 with Caffe).
- Using Binary Logistic Regression to Explain the Impact of Accident Factors on Work Zone CrashesPublication . Santos, Bertha; Picado Santos, Luis; Trindade, ValdemiroFor consolidated road networks, the identification, programming, and implementation of maintenance actions enables addressing the deficiencies identified in the infrastructure, ensuring the provision of an adequate service to users. The performance of such actions along the infrastructure lifetime makes it necessary to study the impact that road work zones may have on road crashes since these areas change locally and temporarily the traffic conditions offered to users (lower speeds, the presence of work equipment and workers, narrow lanes, changes in vertical and horizontal signs, etc.). This study aims to analyze the Portuguese official road work zones crash data from 2013-2015 period by using binary logistic regression models to identify the most significant factors influencing work zone crashes. Official data was processed in order to be used in a statistical analysis software and the binary logistic regressions were performed for the analysis of Portuguese work zone crashes by the type of crash (pedestrian, angle, rear-end and run-off-road), driver age groups (under 25 years, 25 to 64 and over 65 years) and a predominant contributing factor as speeding, unexpected obstacle on the road and the disregard for vertical road signs and safety distance (main contributing factors identified in this study). Results obtained shows that factors as “urban environment”, “one driver involved is running straightly”, “clean and dry pavement” and “daylight” have positive impact in a large number of models. The identification of these factors allows supporting the definition of strategies aimed at the reduction of the number and severity of crashes in road work areas.
- Portuguese Cistercian Churches - An acoustic legacyPublication . Rodrigues, Fabiel G.; Lanzinha, João; Martins, Ana Maria TavaresThe Cistercian Order (11th century) stands out as an apologist of the simplicity and austerity of the space. According to the Order of Cîteaux, only with an austere space, without any distractions, the true spiritual contemplation is achieved. This Order was an aggregator and consolidator pole during the Christian Reconquest. Thus, as it happens with other Religious Orders, Cîteaux has a vast heritage legacy. This heritage is witness, not only of the historical, but also social, political, and spiritual evolution. This legacy resumes the key principles to an austere liturgy, which requirements, in the beginning, are based on the simplicity of worship and of the connection between man and God. Later, these requirements allowed the development of the liturgy itself and its relation with the believers. Consequently, it can be concisely established an empirical approach between the Cistercian churches and the acoustics conditioning of these spaces. This outcome is fundamental in order to understand the connection between liturgy and the conception of the Cistercian churches as well as the constructed space and its history. So, an analysis of these principles is essential to establish the relation between acoustic and religious buildings design throughout history. It is also a mean of understanding the knowledge of acoustics principles that the Cistercian Order bequeathed to Portugal. This paper presents an empirical approach on Cistercian monastic churches acoustics. These spaces are the place where the greatest acoustic efforts are concentrated and it is also the space where the liturgy reaches greater importance. On the other hand, Portugal is a country which has an important Cistercian legacy over several periods of history. Consequently, the portuguese Cistercian monastic churches are representative of the development of the liturgy, the design of spaces and of the acoustic requirements of their churches since the 12th century until the 21st century and it is of great importance to implement this study.
- Optimization of acid sulfite pretreatment in the enzymatic hydrolysis of Cytisus striatusPublication . Vaz, Álvaro; Gomes, Tânia; Simões, RogérioEthanol production from lignocellulosic material includes three major steps: biomass pretreatment, which fragments the lignocellulosic matrix to facilitate the enzymes access to the substrate; hydrolysis, where the polysaccharides are converted into fermentable sugars (e.g. glucose and xylose); and finally, fermentation that produces ethanol or other biologically based chemicals (e.g. lactic acid, succinic acid). The aim of the present work was to study the effect of some operative variables of the pretreatment stage, namely sodium h ydrogen sulfite and sulfuric acid loadings, temperature and time, on the release of sugars in enzymatic hydrolysis, performed applying a Novozymes® cocktail, with fixed charges and operating conditions. Cystisus striatus wood branches were chipped and submitted to different reaction conditions, with a central composite experimental design 2^4+star, exploring the following variables: sulfuric acid charge (0-3%, on wood), sodium bisulfite charge (0-4 %, on wood), maximum temperature (150-190ºC) and time at maximum temperature (0-30 minutes). After pretreatment, the acid hydrolysates were recovered and the solid residues were mechanically disintegrated and thereafter subjected to enzymatic hydrolysis with an enzymatic cocktail from Novozymes®. Sugars and by-products released in the sulfite pretreatment and enzymatic treatment hydrolysates were analyzed by HPLC. The percentage of material released in the acid hydrolysates was between 7 and 29.1%. Temperature and sulfuric acid load were the most important tested variables. The inhibition products represented less than 0.9% of the initial wood mass, even for the most severe reaction conditions. Enzymatic hydrolysis of polysaccharides on solid residues resulted in conversions from 6.0 to 68.9%, depending on the reaction conditions used in biomass pretreatment with sulfite and sulfuric acid. The rate of sugars release proved to be high at the beginning, gradually decreasing with contact time. The experimental data analysis using Statgraphics®Plus5 enabled us to obtain correlation expressions and conclude that all study variables influence this phase of the process, mainly temperature and sulfuric acid load. For a given sulfite load, more acidic conditions led to higher sugar release and greater fragmentation of the material, but also higher production of degradation products; moderate sodium bisulfite (1%) and sulfuric acid (2.25%) loads released practically all hemicelluloses in the raw material.
- Refining rheological response of chemical pulp fibre suspensionsPublication . Vaz, Álvaro; Simões, Rogério; Silvy, JacquesThe purpose of this work was to study the influence of the refining operating variables on the rheological response of chemical pulp fibre suspensions using a Valley beater. Pinus sylvestris, Eucalyptus globulus and Betula verrucosa bleached pulps were used. The normal and tangential average forces exerted on the pulp suspension in the gap clearance were evaluated, the gap between rotor and stator was measured and the apparent viscosity evolution during refining was obtained. The refining essays took place in a laboratory Valley beater, and the studied variables were the load on the roll, the rotor speed of rotation and the specific applied energy. Relationships between apparent viscosity and shear rate were tested for the three species fibre suspensions, which showed shear-thinning behaviour (Fig.1). The results were analysed in terms of fiber and flock properties. The computed crowding factors, Nc, (Kerekes and Schell) decrease from pine to eucalypt to birch. Thus, flock dimensions and resistance are significantly higher for pine. Pine had significantly wider gap, due to its greater and more resistant flocks. This produced smaller shear rate and thus higher apparent viscosity. The smaller and weaker eucalyptus and birch flocks induced smaller gaps, higher shear rates and smaller apparent viscosity. For each pulp suspension, the apparent viscosity diminished with refining time due to increased fibre flexibility and shortening, which promoted smaller flocks and reduced gap clearance (producing higher shear rates). The different rheological behaviors under the same operating conditions for different pulps lead to the inference that from the hydrodynamical point of view one should treat pulps with different morphological characteristics separately, considering the optimization of the energy transfer efficiency in pulp refining.
- Undoing gender inequalities in Portugal: a long and winding roadPublication . Schouten, Maria Johanna ChristinaOver the past one hundred years, the movement towards gender equality has known advances and setbacks, in Portugal and all over the world. While acknowledging and outlining the major favourable developments, this paper discusses mainly some tendencies in the opposite direction, in particular those that increasingly emphasize and encourage, from an early age, differences between men and women, usually to the detriment of the latter. Examples in Portugal include the growing genderization of children’s toys and books (which in one case has triggered a widely-mediatized polemic in September 2017) and the importance of the colours pink and blue. After childhood, differences persist regarding choice of study, professional activities, salary and domestic responsibilities. In this respect, sociological research in Portugal has observed a backlash in the position of women, in particular as an effect of the 2010-2014 financial and economic crisis.