Tolerant, broadband tunable 2 × 2 coupler circuit

We propose a circuit design for a broadband tunable 2 x 2 waveguide coupler, consisting of a two-stage Mach-Zehnder interferometer with electro-optic phase shifters in each stage. We demonstrate that such design can be configured as a tunable coupler with arbitrary coupling ratio and with a uniform response over 50-nm spectral range around 1550 nm. The design is also tolerant to fabrication variations that affect the coupling ratios of the directional couplers

Growth, Inequality and Poverty: Some Empirical Evidence from Minas Gerais State, Brazil

This chapter is motivated by the fact that the Brazilian economy has one of the highest income inequality index in the world. According to Paes de Barros et al(2000), average income of the 10% richest people in Brazil is 28 times higher than the average income of the 40% poorest people. In Argentina, it is 10 times, 13 times in Costa Rica and 5 times in France. Brazilian growth did not benefit all classes and inequality is increasing since the 60´s. While the 10% richest people get 48% of total income, the 10% poorest people get 0,8% of total income. The inequality problem also arises in the Brazilian regional income analysis. Minas Gerais is a rich and dynamic state with 300.000 km2 divided into 10 different regions, 66 microregions and 853 towns. It is located in the Southeast developed part of the country and is responsible for 10% of Brazilian GDP. As the rest of Brazil, it has a dual economy with prosperity and poverty and social and economic heterogeneity. This chapter empirically analyses the economic growth and income inequality behavior in Minas Gerais towns and microregions from 1970 to 2000, using the income convergence hypothesis. Convergence tests such as Barro and Sala-i-Martin(1992), σ- convergence, Drennan & Lobo(1999) and Quah(1993) are performed. The role of human capital in growth is analysed for Minas Gerais 66 microregions. A comparison is also made between very rich regions and very poor regions of this state to see the relationship between regional inequality and poverty.

Thermo-optical phase shifter with integrated diodes for multiplexed control

We present a thermo-optic silicon phase shifter with integrated diode, which allows multiplexed access to heaters and reduces the number of pads to drive complex silicon photonics circuits. We also demonstrate that such heaters can be driven using digitally modulated signals, which increases the linearity of the phase shift response of the device

Espaços modelo e seus operadores

Orientador: Sahibzada Waleed NoorDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação CientíficaResumo: Alguns dos resultados mais importantes em teoria de operadores tratam da modelagem de grandes classes de operadores abstratos através de operadores concretos em espaços mais conhecidos. Nesse sentido, Sz.-Nagy e Foias observaram a correspondência existente entre uma vasta família de contrações definidas em um espaço de Hilbert separável e as restrições do adjunto do bem conhecido operador shift a seus subespaços invariantes. O sucesso de tal modelagem foi tamanho que provocou o desenvolvimento do estudo das propriedades de tais subespaços que posteriormente ficaram conhecidos como "espaços modelo". O objetivo deste trabalho é dar uma breve introdução à teoria destes espaçosAbstract: Some of the most important results in operator theory deal with modelling large classes of abstract operators as concrete operators on more well-known spaces. In light of this, Sz.-Nagy and Foias observed a correspondence between a vast family of contractions defined on a separable Hilbert space and the restrictions of the adjoint of the famous shift operator to its invariant subspaces. Such modelling achieved such a great success that stimulated the study of the properties of these subspaces which became later known as "model spaces". The main purpose of this text is to present a brief introduction to the theory of such spacesMestradoMatematicaCAPE

Column-row addressing of thermo-optic phase shifters for controlling large silicon photonic circuits

We demonstrate a time-multiplexed row-column addressing scheme to drive thermo-optic phase shifters in a silicon photonic circuit. By integrating a diode in series with the heater, we can connect $N \times M$ heaters in an matrix topology to $N$ row and $M$ column lines. The heaters are digitally driven with pulse-width modulation, and time-multiplexed over different channels. This makes it possible to drive the circuit without digital-to-analog converters, and using only $M+N$ wires. We demonstrate this concept with a $1 \times 16$ power splitter tree with 15 thermo-optic phase shifters that are controlled in a $3 \times 5$ matrix, connected through 8 bond pads. This technique is especially useful in silicon photonic circuits with many tuners but limited space for electrical connections

Relevância informacional dos principais assuntos de auditoria

Este trabalho tem como objetivo investigar se os principais assuntos de auditoria (PAAs) contidos na divulgação anual das demonstrações financeiras padronizadas (DFPs) das companhias listadas trouxeram relevância informacional para os investidores. O estudo preenche uma lacuna da literatura ao avaliar a reação do mercado em relação à publicação das informações contidas nos PAAs no Brasil, o qual passou a ter divulgação obrigatória para as companhias listadas a partir das demonstrações financeiras referentes ao exercício de 2016. O tema em análise tem relevância prática, pois o uso dos PAAs nos relatórios do auditor independente tende e crescer e se expandir para as demais companhias abertas, além das companhias listadas. O trabalho traz uma contribuição para o regulador do mercado de capitais (Comissão de Valores Mobiliários – CVM) e para o Instituto dos Auditores Independentes do Brasil (IBRACON) no que tange ao entendimento dos impactos do novo relatório do auditor, possibilitando o aperfeiçoamento e a ampliação desse mecanismo. Para a análise, utilizou-se a metodologia de estudo de eventos, que consiste em avaliar como a informação influencia o mercado em um determinado período associado à ocorrência do evento de divulgação. Para tanto, utilizou-se a variação da soma dos retornos anormais diários de cada companhia nos dias que fazem parte da janela de divulgação das informações. Os resultados deste estudo apontam para a consistência do conteúdo informativo das demonstrações financeiras com a emissão dos PAAs, na medida em que a variação do retorno anormal acumulado das empresas analisadas tem associação positiva com os retornos acumulados na janela de divulgação da informação das DFPs a partir do ano de adoção do novo relatório do auditor independente. Assim, este trabalho contribui para a literatura, apresentando evidências empíricas da relevância informacional do conteúdo do novo relatório de auditoria contendo os PAAs.This paper aims to investigate whether the key audit matters (KAMs) contained in the annual standardized financial statements (SFSs) of Brazilian listed companies have contributed with informational relevance for investors. The study fills a gap in the literature by evaluating the Brazilian market’s reaction to the disclosure of the information contained in the KAMs, which became mandatory for listed companies to disclose in their financial statements as of the 2016 fiscal year. The topic under analysis is of practical relevance as the use of KAMs in the independent auditor’s report is growing and expanding to other publicly-held companies in addition to listed ones. This study provides a contribution to the Brazilian capital market regulator (Comissão de Valores Mobiliários – CVM) and the Institute of Independent Auditors of Brazil (Ibracon) regarding understanding the impacts of the new auditor’s report, thus enabling the improvement and expansion of this mechanism. For the analysis, we use the event study methodology, which consists of evaluating how information influences the market in a particular period associated with the occurrence of a disclosure event. To do so, we used the variation in the sum of the daily abnormal returns of each company on the days that form part of the information disclosure window. The results of this paper indicate the consistency of the informative content of the financial statements with KAMs, insofar as the variation in the cumulative abnormal return of the companies analyzed is positively associated with the cumulative returns in the information disclosure window for the SFSs following the adoption of the new independent auditor’s report. Thus, this paper contributes to the literature by presenting empirical evidence of the informational relevance of the content of the new audit report containing KAMs