Social ties and economic development

We develop a parsimonious general equilibrium model where agents allocate time across three activities: production, trade, and leisure. Leisure includes time spent socializing, which economizes transaction costs. Our framework yields multiple equilibria in terms of the number of social ties and predicts that the number of social ties is positively associated with development, a relationship we observe in cross-country data. The model captures additional dimensions of data, namely: (i) increasing income inequality, but converging growth rates; (ii) an association between weak social ties and development; and (iii) an association between number of social ties and size of the transaction sector.social capital; development; transaction costs; networks

Technological specialization and the decline of diversified firms

We document a strong decline in corporate-diversification activity since the late 1970s, and we develop a dynamic model that explains this pattern, both qualitatively and quantitatively. The key feature of the model is that synergies endogenously decline with technological specialization, leading to fewer diversified firms in equilibrium. The model further predicts that segments inside a conglomerate should become more related over time, which is consistent with the data. Finally, the calibrated model also matches other empirical magnitudes well: output growth rate, market-to-book ratios, diversification discount, frequency and returns of diversifying mergers, and frequency of refocusing activity.otherpublishe

an agent-based model of optimal exploitation

Using an agent-based simulation, we illustrate how goal-seeking behavior affects network formation, learning, and performance. Our organization has one manager, who decides where to invest financial capital; individual workers, who decide where to work and prefer projects with larger budgets; and projects, which vary in quality. Our manager discovers high-quality projects from interactions with workers and allocates more capital to high-quality projects. When given an opportunity, our workers move to bigger-budget projects. We let our manager vary in terms of how much she exploits what she learns and allow our workers vary in terms of how sensitive they are to differences in capital. Our results highlight a contingency which shapes how goal-seeking behavior affects learning. The contingency is network fragility. Fragile connections decay quickly when individuals are not working together, while robust relationships decay more slowly. When relationships are robust, exploitation by our manager leads to a dense organizational network, improving information quality, and performance. Decisions by self-interested individuals (our manager and our workers) produce a virtuous learning cycle. When relationships are fragile, exploitation by our manager produces a sparse network, reducing information quality, and undermining performance. When network connections are fragile, the manager must find the right balance of exploitation and exploration, a balance which limits the rate at which workers move from one project to the next, allowing the manager to exploit some of what she knows, without undermining the very network which allows for useful information to be obtained.publishersversionpublishe

Notch signaling in the regulation of hematopoietic stem cell

Purpose of Review Understanding the signaling pathways that govern hematopoietic stem and progenitor cells (HSPCs) is fundamental to uncover their regulation and how this is skewed in hematological malignancies. Whether Notch is necessary for the regulation of mammalian HSPCs is still unclear. We therefore critically review the current literature on the role of Notch in HSPCs. Recent Findings HSPCs have shown different requirements for Notch signals in vitro and in vivo and at different stages of differentiation. Additionally, bone marrow niche cells activate Notch signaling in HSPCs enhancing their regenerative and self-renewal capacity. Summary Despite the controversy, adequate levels of Notch signaling appear necessary to avoid the development of hematological malignancies. Contrary to early studies, recent research suggests that Notch signaling may play a role in homeostatic and regenerative hematopoiesis but further investigation is necessary to understand how it is regulated by the different ligand/receptor pairings and the molecular mechanisms that are triggered

Social ties and economic development

We develop a parsimonious general equilibrium model where agents allocate time across three activities: production, trade, and leisure. Leisure includes time spent socializing, which economizes transaction costs. Our framework yields multiple equilibria in terms of the number of social ties and predicts that the number of social ties is positively associated with development, a relationship we observe in cross-country data. The model captures additional dimensions of data, namely: (i) increasing income inequality, but converging growth rates; (ii) an association between weak social ties and development; and (iii) an association between number of social ties and size of the transaction sector

Social ties and economic development

We develop a parsimonious general equilibrium model where agents allocate time across three activities: production, trade, and leisure. Leisure includes time spent socializing, which economizes transaction costs. Our framework yields multiple equilibria in terms of the number of social ties and predicts that the number of social ties is positively associated with development, a relationship we observe in cross-country data. The model captures additional dimensions of data, namely: (i) increasing income inequality, but converging growth rates; (ii) an association between weak social ties and development; and (iii) an association between number of social ties and size of the transaction sector

Educação em sustentabilidade : proposta metodológica de incentivo a prática de quintais domésticos

Orientador :Monografia (especialização) - Universidade Federal do Paraná, Setor de ..., Curso de Especialização em ...Inclui referência

Performance Evaluation Analysis of Spark Streaming Backpressure for Data-Intensive Pipelines

A significant rise in the adoption of streaming applications has changed the decisionmaking processes in the last decade. This movement has led to the emergence of several Big Data technologies for in-memory processing, such as the systems Apache Storm, Spark, Heron, Samza, Flink, and others. Spark Streaming, a widespread open-source implementation, processes data-intensive applications that often require large amounts of memory. However, Spark Unified Memory Manager cannot properly manage sudden or intensive data surges and their related inmemory caching needs, resulting in performance and throughput degradation, high latency, a large number of garbage collection operations, out-of-memory issues, and data loss. This work presents a comprehensive performance evaluation of Spark Streaming backpressure to investigate the hypothesis that it could support data-intensive pipelines under specific pressure requirements. The results reveal that backpressure is suitable only for small and medium pipelines for stateless and stateful applications. Furthermore, it points out the Spark Streaming limitations that lead to in-memory-based issues for data-intensive pipelines and stateful applications. In addition, the work indicates potential solutions.N/

Recomendação de navegação em portais da internet como um serviço suportado em ferramentas Web Analytics

Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre de Sistemas de Informação OrganizacionaisCom o constante crescimento da utilização da Internet o número de websites e respetivas páginas contínua a evoluir também, por este motivo, verifica-se uma necessidade de alinhar a experiência de utilização com os objetivos gerais de um website. Para satisfazer esta necessidade o sistema de recomendação proposto sugere páginas ao utilizador que possam ser do seu interesse com base em perfis de navegação de um website em geral. A maioria dos sistemas de recomendação são baseados em regras de associação ou palavras chave (quando o conteúdo é considerado). No entanto, quando os dados não são suficientes ou são muito dispersos e a ordem é considerada, uma abordagem tradicional pode ser inadequada. Por outro lado, assumindo outro paradigma, a área de Web Analytics, tem obtido um crescimento considerável, através de ferramentas robustas que permitem a recolha e análise de dados da internet, a fim de compreender e otimizar eficiência e eficácia do website. O presente artigo propõe o desenvolvimento de um sistema de recomendação baseado na ferramenta Google Analytics. O protótipo é composto por dois componentes principais que são: 1) um serviço responsável pela construção e lógica associada à criação das recomendações; 2) uma biblioteca incorporável em qualquer website que providenciará um widget de recomendação configurável. Avaliações preliminares constataram que a implementação segue a lógica do modelo proposto.As the Internet usage keeps increasing, the number of web sites and hence the number of web pages also keeps increasing, so there is a need to align the user experience with the overall websites purposes. Toward this requirement, the proposed recommendation systems suggest the user pages that might be of its interest based on past navigation profiles of overall site usage. Most of existing recommendation systems are based on association rules or based on keywords (when content is considered). However, on usage data shortage or sparse data and if sequential order is to be considered such traditional approaches may become unsuitable. Conversely, the Web Analytics arena, assuming other paradigm, has experienced a considerable growth through mature tools that allow the collection and analysis of internet data in order to understand and optimize website efficiency and efficacy. This work proposes the development of a recommendation system based on the Google Analytics tool. The prototype is constituted by two main components which are: 1) a service responsible for the construction and associated logic that underlies recommendations generation; 2) an embeddable library on any website that will furnish website with a configurable recommendation widget. Preliminary evaluations had showed that the implementation follows the logic of the proposed model