Corrupting Learning: Evidence from Missing Federal Education Funds in Brazil

While cross-country analysis suggests that corruption hinders economic growth, we have little evidence on the mechanisms that link corruption to long-run economic development. We provide micro-evidence on the consequences of corruption for the quality of education. We use data from the auditing of Brazil’s local governments to construct objective measures of corruption involving educational block grants transferred from the central government to municipalities. Using variation in the incidence of corruption across municipalities and controlling for students’, schools’ and municipal characteristics, we find that corruption significantly reduces the school performance of primary school students. Students residing in municipalities where corruption in education was detected score 0.35 standard deviations less on standardized tests, and have significantly higher dropout and failure rates. We also provide evidence on the mechanisms that link corruption and mismanagement to learning and school attainment. The results are consistent with corruption directly affecting economic growth through the reduction of human capital accumulation. JEL Codes: D73, I21, H72

Optical solitons in inhomogeneous quadratic media

Tese de doutoramento, Física, Universidade de Lisboa, Faculdade de Ciências, 2013In this thesis we investigate optical solitons in systems with spatial modulations of the Dielectric Permittivity (DP) and quadratic nonlinear susceptibility x(2) that are transverse to the propagation of light. We consider three physical arrangements. The first consists in a periodic modulation of the DP and x(2) in a lossless medium. The second system considers a medium with gain and loss terms in the DP which satisfy the PT-symmetry, i.e., the real part of the dielectric permittivity is even in respect to the transverse spatial coordinate, while the imaginary part, responsible for the gain and loss, is odd. It is also assumed a constant x(2). In the third system we consider a localized DP with gain and loss DP which satisfy the PT -symmetry, with constant x(2). The study of solitons is a very important topic of fundamental research which also has found practical applications, specially as a medium to carry digital information. Nonlinear systems such as the ones investigated in this thesis, with quadratic nonlinearity, were found to exhibit interesting applications such as conversion of infrared radiation into visible light and all-optical switching in multichannel optical communication systems. The search for solitonic solutions in the present thesis is done using several numerical methods such as a shooting algorithm and Newton- Raphson, used to find solutions and a split-step method to study the dynamics of solitons. The implementation of the methods relies on the careful analysis of symmetry and asymptotic properties of the systems under investigation. The stability of solutions is, in addition to numerical evaluation of perturbed solitons, studied by linear stability analysis in all cases and links between the two approaches are discussed. The phenomenon of bistability occurs in the periodic lossless system, as two stable solutions can exist with same power and different symmetries and corresponding symmetry axes. An effective equation with cubic nonlinearity that successfully predicts when bifurcations occurs is presented. The PT-symmetric system with periodic DP is found to support three different types of bifurcations, related to the edge of the gap where it occurs, it can be an edge of the Fundamental Field (FF), Second- Harmonic (SH) or both. Quadratic solitons in this system support stable embedded solitons in the case fundamental field edge bifurcations. The system with PT-symmetric localized potential supports soliton branches which are limited in maximal power. Three types of bifurcations are discussed in a way similar to the periodic system. We found that branches that bifurcate from a linear mode of the SH can have finite amplitude of the SH component even when the amplitude of the FF goes to zero. In the same previously refered bifurcation, solitons with propagation constant close to the propagation constant of the linear mode can be stable for strengths of gain and loss well above the PT-symmetry breaking treshold.Nesta tese investigamos solitões óticos em sistemas com modulações espaciais da Permitividade Dielétrica (DP) e da susceptibilidade não linear quadrática x(2) transversas à propagação da luz. Consideramos três sistemas físicos. O primeiro consiste numa modulação periódica da DP e x(2) num meio sem perdas. O segundo sistema considera um meio com ganhos e perdas presentes na DP que satisfazem a simetria PT, i.e. a parte real da permitividade dielétrica é par em relação à coordenada espacial transversa, enquanto a parte imaginária, responsável pelos ganhos e perdas, é ímpar e x(2) considerado constante. No terceiro sistema consideramos uma DP localizada, com ganhos e perdas, que satisfaz a simetria PT, com x(2) constante. O estudo de solitons. O estudo de solitões é não somente um importante tópico de pesquisa fundamental, também foram encontradas aplicações práticas, especialmente como um meio de transporte de informação digital. Em sistemas não-lineares como os considerados nesta tese, com não linearidade quadrática, foram descobertas aplicações tais como a conversão de radiação infravermelha em luz visível e comutação feita totalmente óticamente em multicanais de comunicação óticos. A busca por soluções solitônicas é feita nessa tese utilizando vários métodos numéricos tais como um algoritmo de shooting e outro de Newton-Raphson, usados na busca de soluções e um método de split- step utilizado no estudo da dinâmica dos solitões. A implementação dos métodos baseia-se na análise cuidadosa da simetria e do comportamento assintótico dos solitões nos sistemas investigados. A estabilidade das soluções é, em adição à integração numérica das equações de evolução, estudada através da análise de estabilidade linear em todos os casos. Ligações entre as duas análises são estabelecidas. O fenômeno da bi-estabilidade no sistema periódico sem perdas é encontrado, duas soluções estáveis podem ocorrer com a mesma potência com simetrias e centros de simetria diferentes. Uma equação efetiva com não-linearidade cúbica que prevê com sucesso quando uma bifurcação ocorre é desenvolvida. No sistema periódico com simetria PT são encontradas três tipos de bifurcações, relacionadas com qual fronteira do hiato nas constantes de propagação elas ocorrem. Elas podem ser numa fronteira do campo fundamental (FF), do segundo harmônico (SH) ou de ambos. Solitões quadráticos esáveis nesse sistema podem ser encontrados dentro da região de hiato do SH no caso de bifurcações advindas de uma fronteira do FF. No sistema com potencial localizado e simetria PT há ramos de soluções com um máximo nos valores da potência. Três tipos de bifurcações são discutidas numa maneira similar ao sistema periódico. Ramos que bifurcão de um modo linear do SH podem ter amplitudes finitas do componente SH mesmo quando a amplitude do FF aproxima-se de zero. Na mesma bifurcação é encontrado que solitons com constantes de propagação com valores próximos da constante de propagação do modo linear podem ser estáveis mesmo valores de amplitude da parte imaginária da DP muito acima do limiar de quebra de simetria PT.Projeto Estratégico PEst-OE/FIS/UI0618/201

Broadband feed for a parabolic antenna for satellite tracking.

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201

Growth cycles in Latin America and developed countries

The Minskyan approach to financial instability and its effects on the real economy have recently been revived in order to explain the exchange rate crises undergone by the so-called emergent economies. Economies of this type are characterized by repeated scarcity of foreign currency, which can be explained by using Neo-Schumpeterian theory. Based on the Minskyan approach and on the Neo-Schumpeterian literature, this study seeks to demonstrate that there is a cyclic recurrence of exchange rate crises in Latin-American (peripheral) economies. By using data on international liquidity, the balance of payments and the increase in production in the G7 economies and in thirteen Latin-American economies, it was found that the Latin-American economies mirror the cycles of international liquidity.financial instability, national innovation system, cycles

Longitudinal analysis of viral shedding in astronauts before, during, and after a mission to the International Space Station

Trabalho de Projeto de Mestrado, Bioestatística, 2022, Universidade de Lisboa, Faculdade de CiênciasHerpesviruses were measured in 23 astronauts with the objective of understanding their reactivation pattern during a long-duration space mission. The measurements consisted of the number of viral copies of cytomegalovirus (CMV), Epstein-Barr (EBV) and varicella-zoster (VZV) viruses collected at different moments: two before (L−180, L−45 ), three during (Early, Mid, Late) and two after (R+0, R+30 ) a spaceflight. These data present three difficulties: small sample size, zero-inflation and missing responses. The methods used were confidence intervals for proportions, McNemar’s exact test, linear models for categorical data, multiple imputation using chained equations (MICE), and logistic regression mixed models (LRMM). CMV was only measured once during the flight (During). There was significant increase in the reactivation proportion during flight compared to before and after flight measures L−180 and R+30. The LRMM fitted for binary CMV that had moments with reactivation as fixed effects and random effect subject was significant at coefficient R+30 (p=0.043), although During (p=0.078) had a p-value close to the statistical significance of 5%. EBV and VZV were measured in saliva samples and have missing responses for the inflight moments. An increase of the amplitude of reactivation was detected at Late for both viruses. The data seemed to follow a missing-completely-at-random mechanism for both viruses (p=0.490 and 0.070 for EBV and VZV, respectively). Fifty imputed data sets were generated for each virus. For EBV the pooled estimates for the reactivation probability were 0.126, 0.239, 0.454 for Early, Mid, Late, respectively, and for VZV 0.488, 0.330, 0.617, respectively. The pooled LRMM of EBV with L−180 as baseline was significant at L−45 (p=0.029) and Late (p=0.022), and R+0 (p=0.053) was close to significance. For VZV, R+30 was the only significant different from baseline Early(p=0.002). In conclusion, the stress conditions of the spaceflight affected the reactivation dynamics of all three viruses

A Hybrid Experimental-numerical Sif Determination Technique

AbstractHybrid methods, wherefore numerical and experimental data are used to calculate a critical parameter, have been used for several years with great success in Experimental Mechanics and, in particular, in Facture Mechanics. This letter reports on the development of a hybrid methodology for the determination of the stress intensity factor (SIF) parameter, which entails combining experimental and numerical procedures to compute the SIF based of linear elastic fracture-mechanics concepts