Monetary equilibrium with decentralized trade and learning

This paper analyzes the stability of monetary regimes in an economy where fiat money is endogenously created by the government, information about its value is imperfect, and learning is decentralized. We show that monetary stability depends crucially on the speed of information transmission in the economy. Our model generates a dynamic on the acceptability of fiat money that resembles historical accounts of the rise and eventual collapse of overissued paper money. It also provides an explanation of the fact that, despite its obvious advantages, the widespread use of fiat money is only a recent development

Exchange market pressure and the credibility of Macau's currency Board

In this study, we assess the credibility of the currency board arrangement (CBA) of the Macau Special Administrative Region by studying the relationship between exchange market pressure (EMP) and the anchors of a rule-based CBA, namely, interest rate arbitrage, exchange rate arbitrage and economic discipline. A pure CBA signals its credibility by allowing the first two anchors to function automatically and by pursuing sound fiscal policies. The analysis’ results suggest that Macau’s CBA has been characterised by a state of low volatility since late 1992, with the brief exception of the East Asian financial crisis period. The paper’s main finding is that fiscal fundamentals seem to have a more pronounced role in reducing EMP’s variability during periods of low volatility whilst interest rate arbitrage is more important in periods of high volatility. We conclude that Macau’s CBA is credible at present as reflected in the low frequency of observed EMP, in the narrowing of Macau’s interest rate differential vis-à-vis U.S. interest rates and in Macau’s substantial fiscal reserves.

Limited memory and the essentiality of money

This paper investigates the relationship between memory and the essentiality ofmoney. We consider a random matching economy with a large finite population inwhich commitment is not possible and memory is limited in the sense that only afraction m E(0; 1) of the population has publicly observable histories. We show thatno matter how limited memory is, there exists a social norm that achieves the firstbest regardless of the population size. In other words, money can fail to be essentialirrespective of the amount of memory in the economy. This suggests that the emphasison limited memory as a fundamental friction for money to be essential deserves a deeperexamination.

Money versus memory

A well–established fact in monetary theory is that a key ingredient for the essentialityof money is its role as a form of memory. In this paper we study a notion ofmemory that includes information about an agent’s past actions and trading opportunitiesbut, in contrast to Kocherlakota (1998), does not include information aboutthe past actions and trading opportunities of an agent’s past partners. We first showthat the first–best can be achieved with memory even if it only includes informationabout an agent’s very recent past. Thus, money can fail to be essential even if memoryis minimal. We then establish, more interestingly, that if information about tradingopportunities is not part of an agent’s record, then money can be better than memory.This shows that the societal benefit of money lies not only on being a record of pastactions, but also on being a record of past trading opportunities, a fact that has beenoverlooked by the monetary literature.

Monetary equilibrium with decentralized trade and learning

This paper analyzes the stability of monetary regimes in an economy where fiat money isendogenously created by the government, information about its value is imperfect, and learningis decentralized. We show that monetary stability depends crucially on the speed of informationtransmission in the economy. Our model generates a dynamic on the acceptability of fiat moneythat resembles historical accounts of the rise and eventual collapse of overissued paper money.It also provides an explanation of the fact that, despite its obvious advantages, the widespreaduse of fiat money is only a recent development.

Superconductivity from spin fluctuations and long-range interactions in magic-angle twisted bilayer graphene

Magic-angle twisted bilayer graphene (MATBG) has been extensively explored both theoretically and experimentally as a suitable platform for a rich and tunable phase diagram that includes ferromagnetism, charge order, broken symmetries, and unconventional superconductivity. In this work, we investigate the intricate interplay between long-range electron-electron interactions, spin fluctuations, and superconductivity in MATBG. By employing a low-energy model for MATBG that captures the correct shape of the flat bands, we explore the effects of short- and long-range interactions on spin fluctuations and their impact on the superconducting (SC) pairing vertex in the Random Phase Approximation (RPA). We find that the SC state is notably influenced by the strength of long-range Coulomb interactions. Interestingly, our RPA calculations indicate that there is a regime where the system can traverse from a magnetic phase to the SC phase by \emph{increasing} the relative strength of long-range interactions compared to the on-site ones. These findings underscore the relevance of electron-electron interactions in shaping the intriguing properties of MATBG and offer a pathway for designing and controlling its SC phase.Comment: 9 pages, 5 figure

Justicia cordifolia, a new combination in Brazilian Acanthaceae

Este artigo é parte das pesquisas realizadas no âmbito do projeto PELD-BISC.Sericographis cordifolia is reinstated and a new combination Justicia cordifolia is proposed when transferred to Justicia. Additionally, a detailed morphologic description for this species, field photographs, taxonomic and nomenclatural comments, and species conservation status assessed according to IUCN criteria are provided.CNPq / Capes / FAPs / BC-Fundo Newton / PELD nº 15/2016 and FAPESC / 2018TR0928