On the Welfare Properties of the Lucas and Romer Endogenous Growth Models

We present results from quantitative exercises using the Lucas and Romer endogenous growth models, from which we calculate welfare losses from the distortions presented in the Romer model. Moreover, comparing the models to data, we show that an economy governed by the Romer model would attain a higher welfare than one governed by the Lucas model, contrary to what can be interpreted from some previous theoretical contributions.Endogenous Growth, Human Capital, R&D, Welfare.

On the origins of scaling corrections in ballistic growth models

We study the ballistic deposition and the grain deposition models on two-dimensional substrates. Using the Kardar-Parisi-Zhang (KPZ) ansatz for height fluctuations, we show that the main contribution to the intrinsic width, which causes strong corrections to the scaling, comes from the fluctuations in the height increments along deposition events. Accounting for this correction in the scaling analysis, we obtained scaling exponents in excellent agreement with the KPZ class. We also propose a method to suppress these corrections, which consists in divide the surface in bins of size $\varepsilon$ and use only the maximal height inside each bin to do the statistics. Again, scaling exponents in remarkable agreement with the KPZ class were found. The binning method allowed the accurate determination of the height distributions of the ballistic models in both growth and steady state regimes, providing the universal underlying fluctuations foreseen for KPZ class in 2+1 dimensions. Our results provide complete and conclusive evidences that the ballistic model belongs to the KPZ universality class in $2+1$ dimensions. Potential applications of the methods developed here, in both numerics and experiments, are discussed.Comment: 8 pages, 7 figure

Notre Dame Cathedral: Another case in a growing list of heritage landmarks destroyed by fire

[Excerpt] April 16, 2019. After a more than twelve-hour battle involving 600 firefighters [1], the massive blaze that has destroyed much of the timber roof and toppled the Gothic spire of the Notre Dame Cathedral is fully extinguished. The official cause of the fire is still being investigated, but it seems likely that it may have resulted from restoration works taking place in the 850-year-old structure. After surviving the French Revolution and Nazi occupation during World War II, Notre Dame Cathedral, a masterpiece of Gothic architecture, succumbed to a blaze. As if this were not enough, a large number of extraordinary works of art, musical instruments, statues, woodworks, and religious relics, the full list of which is available on the Cathedral’s website [2], may also have been lost, not only due to the heat but also in consequence of the enormous quantities of water used to fight the fire. Even though it may be premature to draw any conclusions regarding this specific case, it is worth reflecting on the fact that Notre Dame Cathedral is just another entry in a long list of cultural heritage landmarks that have been, wholly or partially, tragically destroyed by fire. Among many other significant examples, such as Windsor Castle, York Minster, the Venice and Barcelona opera houses, and Bosnia’s National Library, it is impossible not to make note here of the National Museum of Brazil, which was ravaged by a huge fire on the night of September 2, 2018. Although some items were saved, the early nineteenth-century building was completely destroyed, in addition to more than 90% of its archive of 20 million items [3], including its Egyptology collection, which was one of the largest in Latin America, and some of the oldest human remains ever found in the Americas. […](undefined)info:eu-repo/semantics/publishedVersio

Hybrid Ionic Liquids/Metal Organic Frameworks for CO2/CH4 Separation

Nesta tese produziram-se nove novos materiais compósitos de ZIF-8, uma rede organometálica porosa (MOF), impregnado com diferentes líquidos iónicos (ILs). Estes novos compósitos, designados genericamente por IL@ZIF-8, foram preparados e caracterizados com o objetivo de serem considerados potenciais adsorventes a aplicar em processos de separação por adsorção, tais como o upgrading ou condicionamento de biogás a biometano. Numa primeira fase, a mesma quantidade molar de nove ILs diferentes foi incorporada na estrutura do ZIF-8, garantindo uma comparação válida entre as amostras. O efeito da incorporação do IL na capacidade de adsorção dos materiais compósitos foi estudado, bem como a influência do catião e do anião do IL na capacidade de adsorção de CO2 (dióxido de carbono) e CH4 (metano) e respetivo efeito na seletividade ideal CO2/CH4. A caracterização textural exaustiva a cada material compósito foi feita com recurso a picnometria de He, adsorção-dessorção de N2 a 77 K, difração de raios-X de pó (PXRD), espectroscopia de infravermelho com transformada de Fourier (FT-IR) e microscopia eletrónica de varrimento (SEM). Os resultados de equilíbrio de adsorção-dessorção de CO2 e CH4 nos compósitos mostram que o catião imidazólio com uma curta cadeia alquílica favorece a capacidade de adsorção para estes materiais. No entanto, quem tem um papel mais ativo de adsorção de gás é o anião e o melhor daqueles que foi testado é o acetato. Em termos de seletividade ideal CO2/CH4, em traços gerais, as amostras que capturaram menos gás são as mais seletivas. O compósito C10@ZIF-8 é o material mais seletivo entre 1 e 3 bar; de 4 a 16 bar, C2OH@ZIF-8 é o material mais seletivo, com ganhos médios de quase 25% na seletividade em comparação com o ZIF-8 puro. O compósito C6B(CN)4@ZIF-8 apresenta boa capacidade de adsorção de gás, tendo ao mesmo tempo uma boa seletividade CO2/CH4. O efeito da quantidade de IL impregnada (loading) foi também estudado. Novas amostras C2OH@ZIF-8 e C6B(CN)4@ZIF-8 foram produzidas com diferentes loadings e caraterizadas com as mesmas técnicas anteriormente mencionadas. Os resultados obtidos de equilíbrio de adsorção para estas amostras foram inconclusivos. Este trabalho abre assim as portas para um campo de investigação de novos materiais com resultados potencialmente interessantes em aplicações de adsorção, dada a multitude de ILs e MOFs existentes.For this thesis nine new composite materials of ZIF-8, a porous organometallic network (MOF), impregnated with different ionic liquids (ILs) were produced. These new composites, generically named IL@ZIF-8, were prepared and characterized with the purpose of studying their potential use as adsorbents in adsorption separation processes such as biogas upgrading or biogas to biomethane conditioning. Firstly, the same molar amount of nine different ILs was incorporated in ZIF-8 structure, assuring a valid comparison among samples. IL impregnation effect on the adsorption capacity of the composite materials was studied, as well as the influence of the cation and anion of the IL on the adsorption capacity of CO2 (carbon dioxide) and CH4 (methane) and respective effect on ideal CO2/CH4 selectivity. An exhaustive textural characterization was performed for every composite, such as He pycnometry, N2 adsorption-desorption at 77 K, Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). CO2 and CH4 adsorption-desorption equilibria results indicate that the imidazolium cation with shorter alkyl chains favours the adsorption capacity for these materials. However, it is the anion that has the key role in adsorption capacity; of all tested, the best one was acetate. Generally speaking, CO2/CH4 ideal selectivities show that samples with less adsorption capacity are the most selective. C10@ZIF-8 composite is the most selective material between 1 and 3 bar; from 4 to 16 bar, C2OH@ZIF-8 is the most selective material, with average gains of almost 25% in selectivity when compared to pristine ZIF-8. C6B(CN)4@ZIF-8 presents good gas adsorption capacity, while at the same time showing good ideal CO2/CH4 selectivity. IL loading effect was also tested, with new C2OH@ZIF-8 and C6B(CN)4@ZIF-8 samples with different loadings being manufactured and texturally characterized by the above-mentioned techniques. Adsorption equilibria results for these new samples were inconclusive. This thesis opens new possibilities for the manufacture of good and selective adsorbent materials for adsorption applications, given the amount of existing MOFs and ILs

Recent advances in the assessment of flood risk in urban areas

The adverse effects of flood disasters in urban areas have been increasing in severity and extent over the past years [...]This research was funded by the Portuguese Foundation for Science and Technology (FCT) through thepostdoctoral grant SFRH/BPD/122598/2016

Purinergic Calcium Signaling and Calcium-Activated Chloride Channels in the Supporting Cells of the Peripheral Olfactory Systems

This study is divided in three individual projects focusing on calcium signaling on nonneuronal cells of different peripheral olfactory systems. In particular, I investigated (1) the role of calcium-activated chloride channel TMEM16A in the development of the mouse olfactory epithelium, (2) the functional role of TMEM16A of mouse olfactory epithelium and (3) purinergic receptor mediated calcium signaling in the supporting cells of the vomeronasal organ (VNO). Previous reports showed that TMEM16A is expressed in the olfactory epithelium, where it localizes at the apical surface of supporting cells, more specifically, in their microvilli. To understand the role of TMEM16A on the development of the mouse olfactory epithelium we conducted the first immunohistochemistry study comparing the morphological properties of the olfactory epithelium and nasal glands in TMEM16A wild-type and knockout littermate mice. The genetic ablation of TMEM16A did not affect the maturation of olfactory sensory neurons and the morphology of the ciliary structures. In addition, TMEM16A knockout did not significantly affect the morphology of supporting cells. The average number of supporting cells, olfactory sensory neurons, horizontal and globose basal cells were not significantly different in the two mice models. These results indicate that the genetic ablation of TMEM16A does not affect the development of the olfactory epithelium. To further understand the functional role of TMEM16A, we investigated the presence of calcium-activated chloride currents in the supporting cells of the olfactory epithelium. Whole-cell patch clamp recordings from TMEM16A wild-type and knockout mice showed that the supporting cells of olfactory epithelium had a calcium-activated chloride current that was abolished in TMEM16A knockout mice. Moreover, we found that this calcium-activated currents can also be activated after the stimulation of the cells with ATP, in line with previous reports showing that supporting cells of mouse olfactory epithelium express purinergic receptors. Although the expression of purinergic receptors in supporting cells in the mouse olfactory epithelium is well documented, the expression of these receptors in mouse VNO is still unknown. Here, we conducted the first study in mouse VNO showing that vomeronasal supporting cells also express purinergic ATP receptors. Using confocal calcium imaging recording we found that a large subset of these cells, about 75%, expressed metabotropic purinergic receptors, and a smaller subset of cells, 38%, expressing P2Y2 and/or P2Y4 receptors

Automatic volume inspection for glass blow moulds

In the glass bottle mould making industry, volume control is done by measuring the amount of water needed to fill the mould. This process has several issues. Firstly, it requires a trained operator to properly seal the mould. Secondly, different operators will lead to different volume values. Another issue is related to the time and work necessary for the procedure, which can take up to 20 minutes for a single mould, making it unsuitable to inspect several moulds of the same series. These issues can be solved by automating the procedure. By using reverse engineering systems to obtain the internal cavity surfaces, comparative studies can be done, such as wear study, enabling the optimization of the moulds. The goal of this project is to establish a system to automate the inspection of the moulds which will result in the acquisition of the moulding surfaces. Then, the volume of the moulds and surface deviations in specific areas can be measured. The development of this project focused in two main areas: the development of a script, where the volume is calculated and the surface is inspected, from cloud points, to determine if the mould is in an acceptable state; and the study of technologies capable of acquiring the mould’s surface while simultaneously being automatable. As for this study, several case studies using laser and structured light are performed to understand the abilities and limitations of these technologies. The first study was done using polished cast iron moulds to determine the ability to acquire the surface and obtain the volume. Then, the ability to present proper comparative results is explored by using a set of unpolished cast iron moulds and then these same moulds once polished to verify if the used systems can obtain the deviations between the two situations. Finally, the validation of the technologies was done using a demo bronze mould, where surface deviations were inspected as well as a ring gauge where the inner cylinder was used for inspection. From these cases, the used laser scanner was able to obtain the volumes of the moulds as well as proper comparative results without spray. As for the used structured light system, it proved unable to acquire the surfaces of the moulds and of the ring gauge, requiring spray. Despite this performance, the system is quite automatable and a state-of-the-art structured light system, using blue light, could be used for this purpose. The laser is also a viable solution, but the cost and complexity to automate can be higher than the structured light system