Reducing Latency of DAG-based Consensus in the Asynchronous Setting via the UTXO Model

DAG-based consensus has attracted significant interest due to its high throughput in asynchronous network settings. However, existing protocols such as DAG-rider (Keidar et al., PODC 2021) and ``Narwhal and Tusk'' (Danezis et al., Eurosys 2022) face two undesired practical issues: (1) high transaction latency and (2) high cost to verify transaction outcomes. To address (1), this work introduces a novel commit rule based on the Unspent Transaction Output (UTXO) Data Model, which allows a node to predict the transaction results before triggering the commitment. We propose a new consensus algorithm named ``Board and Clerk'', which reduces the transaction latency by half for roughly 50% of transactions. As the tolerance for faults escalates, more transactions can partake in this latency reduction. In addition, we also propose the Hyper-Block Model with two flexible proposing strategies to tackle (2): blocking and non-blocking. Using our proposed strategies, each node first predicts the transaction results if its proposal is committed and packs this result as a commitment in its proposal. The hyper-block packs the signature of the proposal and the outputs of the consensus layer together in order to prove the transaction results

Conclave: A Collective Stake Pool Protocol

Proof-of-Stake (PoS) distributed ledgers are the most common alternative to Bitcoin’s Proof-of-Work (PoW) paradigm, replacing the hardware dependency with stake, i.e., assets that a party controls. Similar to PoW’s mining pools, PoS’s stake pools, i.e., collaborative entities comprising of multiple stakeholders, allow a party to earn rewards more regularly, compared to participating on an individual basis. However, stake pools tend to increase centralization, since they are typically managed by a single party that acts on behalf of the pool’s members. In this work we propose Conclave, a formal design of a Collective Stake Pool, i.e., a decentralized pool with no single point of authority. We formalize Conclave as an ideal functionality and implement it as a distributed protocol, based on standard cryptographic primitives. Among Conclave’s building blocks is a weighted threshold signature scheme (WTSS); to that end, we define a WTSS ideal functionality — which might be of independent interest — and propose two constructions based on threshold ECDSA, which enable (1) fast trustless setup and (2) identifiable aborts

Map literacy and spatial cognition challenges for student geography teachers in South Africa

South African geography student teachers should master map skills to teach mapwork effectively in their future classrooms. Spatial cognition, prior learning of map skills and map interpretation at secondary school-level are highlighted as being important in furthering map literacy, which is required by geography student teachers. A mixed-method research framework investigated the causes of map literacy difficulties experienced by first year geography student teachers. Lecturers who train prospective teachers should be aware of the conceptual and/or skills-based difficulties associated with poor map literacy amongst their own students in order to address these problems. This paper outlines problems experienced by first year geography student teachers associated with their own acquisition and understanding of mapwork. Furthermore, it argues that without deeper comprehensive development of their own mapwork content knowledge, the geography student teachers’ ability to teach map skills effectively will be adversely affected

Cinco, seis, sete, oito – balde, pano, mãos e chão: proposições (Per)Formativas Contracoreográficas

In this paper we present some aspects of the research developed in the project Cartographies of the Body in the City, between 2015 and 2019, carried out by the Núcleo de Pesquisa, Estudos e Encontros em Dança - onucleo/UFRJ. The practices and reflections proposed here were initially discussed in the doctoral thesis "Choreographies and countercoreographies of uprising: engaging dance, writing and femininity" (2019), from the Universidade do Estado do Rio de Janeiro. We start from some reflections on the colonial legacy of dance when understood as synonymous with choreography, in a brief review of the history of the choreographic. Based on this idea, we propose the use of the term countercoreography as a praxis that guides artistic experimentations and pedagogical practices, summoned by a force of uprising against the secular values that structure the traditional system of teaching stage dances associated with choreography. Next, we present one of the (Per)Formative Counterchoreographic Proposals developed by onucleo: "Collective cleaning of the floor", highlighting the main questions unfolded in these.Dans cet essai, nous présentons quelques aspects de la recherche développée dans le projet Cartographies du corps dans la ville, entre 2015 et 2019, réalisé par le Núcleo de Pesquisa, Estudos e Encontros em Dança - onucleo/UFRJ. Les pratiques et réflexions proposées ici ont été initialement discutées dans la thèse de doctorat " Chorégraphies et contre-corégraphies du soulèvement : engager la danse, l'écriture et la féminité " (2019), de l'Université d'État de Rio de Janeiro. Nous partons de quelques réflexions sur l'héritage colonial de la danse lorsqu'elle est comprise comme synonyme de chorégraphie, en passant brièvement en revue l'histoire de la chorégraphie. Sur la base de cette idée, nous proposons l'utilisation du terme contre-corégraphie comme une praxis qui guide l'expérimentation artistique et les pratiques pédagogiques, convoquée par une force de soulèvement contre les valeurs séculaires qui structurent le système traditionnel d'enseignement des danses scéniques associées à la chorégraphie. Ensuite, nous présentons l'une des propositions contre-chorégraphiques (per)formatives réalisées par onucleo : "Nettoyage collectif du sol", en mettant en évidence les principales questions qui se dégagent de ces expériences.Nesse trabalho apresentamos alguns aspectos da pesquisa desenvolvida no projeto Cartografias do Corpo na Cidade, entre 2015 e 2019, realizada pelo Núcleo de Pesquisa Estudos e Encontros em Dança – onucleo/UFRJ. As práticas e reflexões aqui propostas foram discutidas inicialmente na tese de doutorado “Coreografias e contracoreografias de levante: engajando dança, escrita e feminilidade” (2019), da Universidade do Estado do Rio de Janeiro. Partimos de algumas reflexões sobre o legado colonial da dança quando entendida como sinônimo de coreografia, em uma breve revisão da história do coreográfico. A partir dessa ideia, propomos a utilização do termo contracoreografia como uma práxis que orienta experimentações artísticas e práticas pedagógicas, convocadas por uma força de levante contra os seculares valores que estruturam o tradicional sistema de ensino das danças de palco associadas à coreografia. A seguir, apresentamos uma das Proposições (Per)Formativas Contracoreográficas realizadas pel’onucleo: “Limpeza coletiva do chão”, destacando as principais questões desdobradas nessas vivências

La gestión de la informalidad en Río de Janeiro y Brasil: la frágil sintonía entre los avances del marco regulatorio y la concreción de cambios consistentes en la realidad urbana

En la actualidad, 928 millones de personas —cerca del 32% de la población urbana mundial— viven en asentamientos precarios. Las proyecciones señalan que hacia el año 2020 esta cifra habrá alcanzado el billón y medio de personas (ONU, 2003). El fenómeno de la ocupación informal del suelo urbano en América Latina oscilaba entre un 40 y un 80% de sus 380 millones de habitantes, según los países, en el año 2000 (Fernandes, 2002). Examinando el caso brasileño en particular, los índices de informalidad pueden situarse entre el 14,5 y casi el 55%, considerando únicamente la población residente en favelas (Larangeira, 2002). Para Río de Janeiro, la municipalidad estima en cerca de un millón el número de residentes en favelas, 19,56% de su población total (PCRJ/IPP, 2002)1

Multi-agent system for monitoring temperature in sensing surfaces including hard and soft sensors

In the digital transformation era, the collection of data assumes a crucial relevance. In some applications, the use of real sensors to measure the target parameters is constrained by technical or economical limitations. In such situations, it is required to use alternative techniques based on soft sensors that acquire data by estimating the measurement of a variable through the correlation of the data acquired by the neighbouring sensors. However, the co-existence of real and soft sensors requires a computational infra-structure that integrates these heterogeneous data sources and supports the synchronisation of the monitoring system based on the inputs of different measurement nodes. Multi-agent systems provide this distributed infra-structure for the data collection, ensuring modularity, scalability and reconfigurability capabilities. This paper introduces a multi-agent system approach to create a modular and scalable sensing system, based on a diversity of real and soft sensors, to support the monitoring of temperature in thin-film sensing surfaces. The proposed approach was experimentally tested in a plastic injection process, presenting promising results in terms of accuracy and response time, and allowing to obtain more sampling points through the use of computational techniques to complement the real data.The work reported in this paper was supported by ONSURF - Mobilizar Competências Tecnológicas em Engenharia de Superfícies, Projeto nº POCI-01-0247-FEDER-024521.info:eu-repo/semantics/publishedVersio

Estratégias de marketing para artistas e bandas independentes do gênero rock de Porto Alegre

O presente estudo procurou identificar quais as estratégias de marketing mais adequadas aos artistas e bandas independentes de Porto Alegre - RS identificadas com o gênero musical Rock. Para tanto, foi necessário seguir cinco etapas relacionadas aos músicos em questão: identificação dos segmentos de mercado e da seleção de mercado-alvo, identificação do posicionamento e da diferenciação, realização da análise do ambiente interno e externo, identificação de questões estratégicas relevantes e por fim, a análise do composto de marketing. O método empregado para a realização do estudo foi por meio de uma pesquisa com abordagem qualitativa exploratória, com entrevistas realizadas com artistas independentes, líderes de bandas independentes, produtores musicais e contratantes de estabelecimentos em que estes músicos performam. O estudo levou em consideração para a sua execução a literatura a respeito da formulação de uma estratégia de marketing voltada ao cliente, abrangendo os temas citados nas etapas descritas anteriormente. Por meio dos resultados alcançados, foi possível identificar que a maioria dos músicos deste estudo não utilizam estratégias de marketing adequadas às suas necessidades e, portanto, apresentam resultados insatisfatórios em termos gerais na sua carreira. Entende-se esse fator como proveniente da falta de conhecimento a respeito de gestão de carreira e da teoria de marketing e suas aplicações. Nesse âmbito, a maioria das estratégias de marketing utilizadas por eles seguem sendo executadas de forma instintiva. Contudo, uma parcela reduzida de músicos desta pesquisa apresenta resultados satisfatórios e níveis de entendimento formal de marketing e gestão, proporcionando grandes contribuições em termos de estratégias de marketing utilizadas que podem ser replicadas por outros músicos. Por fim, entende-se que as estratégias de marketing mais adequadas aos artistas e bandas independentes do gênero Rock de Porto Alegre levam em consideração o entendimento prévio acerca do seu público-alvo, segmento de mercado, diferenciação e posicionamento, somado ao conhecimento sobre o ambiente interno e externo à sua carreira, para enfim, utilizá-los por meio de estratégias específicas nas quatro grandes áreas do composto de marketing: produto, preço, distribuição e comunicação.The present study sought to identify the most appropriate marketing strategies for independent artists and bands from Porto Alegre - RS identified with the Rock musical genre. For that purpose, it was necessary to follow five stages related to musicians:identification of market segments and target market selection, identification of positioning and differentiation, analysis of the internal and external environment, identification of relevant strategic issues and, finally, the analysis of the marketing mix. The method used to carry out the study was through research with an exploratory qualitative approach, through interviews with independent artists, leaders of independent bands, music producers and contractors of establishments where these musicians perform. The study took into account for its execution the literature regarding the formulation of a marketing strategy focused on the customer, covering the themes mentioned in the stages described above. Through the results achieved, it was possible to identify that most musicians in this study do not use marketing strategies appropriate to their needs and, therefore, present unsatisfactory results in general terms in their careers. This factor is understood as coming from the lack of knowledge about career management and marketing theory and its applications. In this context, most of the marketing strategies used by them continue to be executed instinctively. However, a small portion of musicians in this research presents satisfactory results and levels of formal understanding of marketing and management, providing great contributions in terms of marketing strategies used that can be replicated by other musicians. Finally, it is understood that the most appropriate marketing strategies for independent artists and bands of the Rock genre from Porto Alegre take into account the prior understanding of their target audience, market segment, differentiation and positioning, in addition to the understanding of the internal and external environment to your career, to finally use them through specific strategies in the four major areas of the marketing mix: product, price, distribution and communication

A motivação em equipas virtuais estudo das teorias e fatores de estímulos

Orientação: Felipa Cristina Henriques Rodrigues Lopes dos ReisUma equipa é um grupo de pessoas que se reúnem para atingir um objetivo comum. Portanto, equipes virtuais ou remotas podem ser definidas como grupos de profissionais geograficamente dispersos, interconectados por meio de plataformas de comunicação digital, com o objetivo de executar uma tarefa específica indicada pela organização. A motivação é um fator importante a considerar ao adotar o trabalho com equipes virtuais e este estudo apresenta correlações entre teorias motivacionais e trabalho virtual, a fim de identificar fatores de estímulo que podem ser aplicados em cenários de trabalho remoto. Esta pesquisa foi desenvolvida a partir de uma revisão da literatura científica e do uso de ferramentas de pesquisa de campo desenvolvidas com base na análise de fatores motivacionais abordados no referencial teórico encontrado no Capítulo I. Um questionário foi aplicado a 700 inquiridos sendo os resultados e análises refletidos nos capítulos III e IV deste trabalho, que correlacionam as perceções dos profissionais com as teorias motivacionais no local de trabalho. A dissertação conclui que métodos motivacionais retornam resultados semelhantes em equipes virtuais e presenciais, com os mesmos fatores de estímulo aplicados em ambos os cenários para obter resultados semelhantes.A team is a group of people who come together to achieve a common goal. Therefore, virtual or remote teams can be defined as geographically dispersed groups of professionals, interconnected through digital communication platforms, in order to perform a specific task indicated by the organization. Motivation is an important factor to consider when adopting work with virtual teams and this study presents correlations between motivational theories and virtual work in order to identify stimulus factors that can be applied in remote work scenarios. This research was developed from a review of the scientific literature and the use of field research tools developed based on the analysis of motivational factors addressed in the theoretical framework found in Chapter I. A questionnaire was applied to 700 respondents and the results and analyzes reflected in chapters III and IV of this paper, which correlate professionals' perceptions with motivational theories in the workplace. The dissertation concludes that motivational methods return similar results in virtual and in-person teams, with the same stimulus factors applied in both scenarios to obtain similar results

Reputation at Stake! A Trust Layer over Decentralized Ledger for Multiparty Computation and Reputation-Fair Lottery

This work leverages on the framework of Karakostas et al. (SCN\u2720) by extending it to the realm of reputation and trust. At the best of our knowledge, it is the first to introduce reputation and trust to proof of stake systems. Namely, we show that their delegation framework can be repurposed to construct a trust layer over a proof of stake consensus protocol in addition to its original stake delegation application. Furthermore, we show that such extension yields a concrete reputation system satisfying the positive results of (1) Asharov et al. (Asiacrypt\u2713), therefore allowing the secure execution of multiparty protocols such as GMW (STOC\u27 87) and Damgard and Ishai (Crypto\u2705), and (2) Kleinrock et al. (Indocrypt\u2720), therefore allowing the construction of Reputation-fair Lottery and therefore Proof of Reputation. More concretely, our devised layer is used to construct a concrete reputation system based on arbitrary stake distribution. In this layer groups of users can freely ``assign their respective trust\u27\u27 to members of a set of trustees, i.e., participants that offered themselves as receivers of such assignment. Furthermore, our work offers the advantage of providing a clear stake based criteria, verifiable in the ledger, and, therefore, naturally resistant to sybil attack, that the set of trustees indeed yields an honest majority. This setting provides a better situation than a simple assumption of honest majority, since it involves stake in a decentralized ledger, and the public verifiability of the reputation score via verification of the stake distribution