"Agglomeration, Inequality and Economic Growth"

The impact of income inequality on economic growth is dependent on several factors, including the time horizon considered, the initial level of income and its initial distribution. Yet, as growth and inequality are also uneven across space, it is also pertinent to consider the effects of the geographical agglomeration of economic activity. Moreover, it would also seem pertinent to consider not just the levels of inequality and agglomeration, but also the changes they undergo (i.e., their within-country evolution) and how these two processes interact with each other. By applying different econometric specifications and by introducing different measures of agglomeration at country level (specifically, urbanization and urban concentration rates), this study analyzes how inequality and agglomeration (both their levels and their evolution) influence economic growth in function of the country’s level of development and its initial income distribution. Our results suggest, in line with previous studies, that while high inequality levels are a limiting factor for long-run growth, increasing inequality and increasing agglomeration have the potential to enhance growth in low-income countries where income distribution remains relatively equal, but can result in congestion diseconomies in high-income countries, especially if income distribution becomes particularly unequal.Agglomeration, urbanization, urban concentration, congestion diseconomies, inequality, growth JEL classification:O1, O4, R1

Further results on elementary Lie algebras and Lie A-algebras.

A finite-dimensional Lie algebra L over a field F of characteristic zero is called elementary if each of its subalgebras has trivial Frattini ideal; it is an A-algebra if every nilpotent subalgebra is abelian. This paper is a continuation of the study of these algebras initiated by the authors in a previous paper. If we denote by $\mathcal{A}$, $\mathcal{G}$, $\mathcal{E}$, $\mathcal{L}$, $\Phi$ the classes of A-algebras, almost algebraic algebras, E-algebras, elementary algebras and $\phi$-free algebras respectively, then it is shown that: \mathcal{L} \subset \Phi \subset \mathcal{G} \mathcal{L} \subset \mathcal{A} \subset \mathcal{E} \mathcal{G} \cap \mathcal{A} = \mathcal{L}. It is also shown that if L is a semisimple Lie algebra all of whose minimal parabolic subalgebras are $\phi$-free then L is an A-algebra, and hence elementary. This requires a number of quite delicate properties of parabolic subalgebras. Finally characterisations are given of $E$-algebras and of Lie algebras all of whose proper subalgebras are elementary

Rumo aos desafios da economia circular : ferramentas de apoio a uma nova estratégia na prática de design

ABSTRACT : The circular economy is a new strategic concept to meet society's needs in a more efficient and sustainable manner based in decoupling the economic growth and welfare from the increase in the consumption of natural resources. It implies the transition from the traditional linear model to a more innovative and circular approach in the development of the economy by designing new products, new services, and new systems, supported, in most cases, by the re-thinking and creation of new business models. Designers and product developers have an important and crucial role to achieve a successful and wide implementation of the concept which has to be accepted and applied in practice by businesses along the whole value chain and meet the current and future needs of consumers and the society. Currently, several methods, principles, practices, tools, training initiatives, and many resources are being developed globally as a result of the wide exploitation of the concept, but there is still a large gap between what is available to companies and designers, and what is applied in practice on product and service development. This paper reflects part of the PhD research project under development by the authors which is based on the promotion of the design practice within Circular Economy. It explores the results of the review of circularity tools available that can be used by design professionals to systematize and guide their development process. The analysis will support the development of a toolkit and guidelines oriented for the practical implementation of the circular economy in the development of innovative and efficient products and services. (Camocho, Ferreira, & Vicente, 2018).A economia circular é um novo conceito estratégico que visa responder às necessidades da sociedade de uma forma mais eficiente e sustentável que se baseia na dissociação entre crescimento económico e bem-estar do aumento do consumo de recursos naturais. Esta transição, do modelo linear tradicional para uma abordagem mais inovadora e circular no desenvolvimento da economia implica o desenvolvimento de novos produtos, novos serviços e novos sistemas, apoiados, na maioria dos casos, no repensar e na criação de novos modelos de negócio. Os designers e os responsáveis pelo desenvolvimento de produtos têm um papel importante e crucial para alcançar uma implementação ampla e bem-sucedida do conceito. Este deve ser aceite e aplicado na prática pelas empresas ao longo de toda a cadeia de valor atendendo às necessidades atuais e futuras dos consumidores e da sociedade. Atualmente, vários métodos, princípios, práticas, ferramentas, iniciativas de formação e outros recursos têm sido desenvolvidos globalmente como resultado da ampla exploração do conceito, no entanto, ainda existe uma grande lacuna entre o que está disponível para empresas e designers e o que é aplicado na prática no desenvolvimento de produtos e serviços. Este artigo reflete parte do projeto de investigação de doutoramento em desenvolvimento pelos autores, o qual se baseia na promoção da prática de design no âmbito da Economia Circular. Explora os resultados da revisão de ferramentas de circularidade disponíveis que podem ser aplicadas pelos profissionais de design na sistematização e orientação do processo de desenvolvimento. Esta análise irá apoiar o desenvolvimento de um conjunto de ferramentas e orientações para a implementação prática da economia circular no desenvolvimento de produtos e serviços mais inovadores e mais eficientes. (Camocho, Ferreira & Vicente, 2018).info:eu-repo/semantics/publishedVersio

Improved construction of irregular progressive edge-growth Tanner graphs

The progressive edge-growth algorithm is a well-known procedure to construct regular and irregular low-density parity-check codes. In this paper, we propose a modification of the original algorithm that improves the performance of these codes in the waterfall region when constructing codes complying with both, check and symbol node degree distributions. The proposed algorithm is thus interesting if a family of irregular codes with a complex check node degree distribution is used.Comment: 3 pages, 3 figure

Blind Reconciliation

Information reconciliation is a crucial procedure in the classical post-processing of quantum key distribution (QKD). Poor reconciliation efficiency, revealing more information than strictly needed, may compromise the maximum attainable distance, while poor performance of the algorithm limits the practical throughput in a QKD device. Historically, reconciliation has been mainly done using close to minimal information disclosure but heavily interactive procedures, like Cascade, or using less efficient but also less interactive -just one message is exchanged- procedures, like the ones based in low-density parity-check (LDPC) codes. The price to pay in the LDPC case is that good efficiency is only attained for very long codes and in a very narrow range centered around the quantum bit error rate (QBER) that the code was designed to reconcile, thus forcing to have several codes if a broad range of QBER needs to be catered for. Real world implementations of these methods are thus very demanding, either on computational or communication resources or both, to the extent that the last generation of GHz clocked QKD systems are finding a bottleneck in the classical part. In order to produce compact, high performance and reliable QKD systems it would be highly desirable to remove these problems. Here we analyse the use of short-length LDPC codes in the information reconciliation context using a low interactivity, blind, protocol that avoids an a priori error rate estimation. We demonstrate that 2x10^3 bits length LDPC codes are suitable for blind reconciliation. Such codes are of high interest in practice, since they can be used for hardware implementations with very high throughput.Comment: 22 pages, 8 figure

Untainted Puncturing for Irregular Low-Density Parity-Check Codes

Puncturing is a well-known coding technique widely used for constructing rate-compatible codes. In this paper, we consider the problem of puncturing low-density parity-check codes and propose a new algorithm for intentional puncturing. The algorithm is based on the puncturing of untainted symbols, i.e. nodes with no punctured symbols within their neighboring set. It is shown that the algorithm proposed here performs better than previous proposals for a range of coding rates and short proportions of punctured symbols.Comment: 4 pages, 3 figure

Rate Compatible Protocol for Information Reconciliation: An application to QKD

Information Reconciliation is a mechanism that allows to weed out the discrepancies between two correlated variables. It is an essential component in every key agreement protocol where the key has to be transmitted through a noisy channel. The typical case is in the satellite scenario described by Maurer in the early 90's. Recently the need has arisen in relation with Quantum Key Distribution (QKD) protocols, where it is very important not to reveal unnecessary information in order to maximize the shared key length. In this paper we present an information reconciliation protocol based on a rate compatible construction of Low Density Parity Check codes. Our protocol improves the efficiency of the reconciliation for the whole range of error rates in the discrete variable QKD context. Its adaptability together with its low interactivity makes it specially well suited for QKD reconciliation