Fractal structures for the Jacobi Hamiltonian of restricted three-body problem

International audienceWe study the dynamical chaos and integrable motion in the planar circular restricted three-body problem and determine the fractal dimension of the spiral strange repeller set of non-escaping orbits at different values of mass ratio of binary bodies and of Jacobi integral of motion. We find that the spiral fractal structure of the Poincaré section leads to a spiral density distribution of particles remaining in the system. We also show that the initial exponential drop of survival probability with time is followed by the algebraic decay related to the universal algebraic statistics of Poincaré recurrences in generic symplectic maps

Prospects of BRICS currency dominance in international trade

During his state visit to China in April 2023, Brazilian President Lula proposed the creation of a trade currency supported by the BRICS countries. Using the United Nations Comtrade database, providing the frame of the world trade network associated to 194 UN countries during the decade 2010 - 2020, we study a mathematical model of influence battle of three currencies, namely, the US dollar, the euro, and such a hypothetical BRICS currency. In this model, a country trade preference for one of the three currencies is determined by a multiplicative factor based on trade flows between countries and their relative weights in the global international trade. The three currency seed groups are formed by 9 eurozone countries for the euro, 5 Anglo-Saxon countries for the US dollar and the 5 BRICS countries for the new proposed currency. The countries belonging to these 3 currency seed groups trade only with their own associated currency whereas the other countries choose their preferred trade currency as a function of the trade relations with their commercial partners. The trade currency preferences of countries are determined on the basis of a Monte Carlo modeling of Ising type interactions in magnetic spin systems commonly used to model opinion formation in social networks. We adapt here these models to the world trade network analysis. The results obtained from our mathematical modeling of the structure of the global trade network show that as early as 2012 about 58 percent of countries would have preferred to trade with the BRICS currency, 23 percent with the euro and 19 percent with the US dollar. Our results announce favorable prospects for a dominance of the BRICS currency in international trade, if only trade relations are taken into account, whereas political and other aspects are neglected.Comment: 18 pages, 3 figures. Appendix: 4 figures and 3 table

Pedagogical affect, student interest, and learning performance

Using a sample of more than 1000 students, this study reveals that students’ perceived learning depends directly on their interest, pedagogical affect, and their learning performance and indirectly on the student–instructor interaction, the instructor's responsiveness, course organization, the instructor's likeability/concern, and the student's learning performance. Likeability/concern indirectly affects student interest by influencing learning performance. The results yield recommendations for schools, department heads, and university administrators.This research was funded by a research grant from NOVA EGIDE to Luís Filipe Lages. The authors acknowledge the two anonymous JBR reviewers for their feedback on a previous version of the article

A sustentabilidade das carreiras militares e a complementaridade entre as formas de prestação de serviço nas Forças Armadas

A profissionalização das Forças Armadas portuguesas assente num modelo de voluntariado veio a alterar a gestão dos seus recursos humanos no atual modelo de Serviço Militar em resultado das missões que lhes foram conferidas. Este estudo teve como objetivo propor contributos para reforçar as Formas de Prestação de Serviço na categoria de Praças nas Forças Armadas portuguesas, seguindo uma metodologia baseada num raciocínio indutivo, apoiada numa estratégia de investigação qualitativa e num desenho de pesquisa de estudo de caso. Da análise documental e do conteúdo das entrevistas semiestruturadas a oito especialistas nacionais (miliares e civis) com responsabilidade na área dos recursos humanos concluiu-se que nas Praças o Regime de Contrato é o que mantém a estabilidade do efetivo e a principal fonte de recrutamento para os Quadros Permanentes (pilar de estabilidade), ao invés do Regime de Voluntariado, só existente no Exército. Adicionalmente, o Regime de Contrato Especial oferece maior permanência e um aumento de qualificações técnicas. Dos request for information aos Adidos de Defesa junto das Embaixadas da Alemanha, França, Espanha e Reino Unido, identificaram-se as suas principais tendências, consubstanciadas em regimes de curta e longa duração, características passiveis de serem consideradas nos modelos existentes nas Forças Armadas portuguesas.The professionalization of the Portuguese Armed Forces based on a voluntary model has changed the management of their human resources in the current model of Military Service because of the missions assigned to them. This study aimed to propose contributions to reinforce the Military Forms of Service Provision in the category of enlisted men in the Portuguese Armed Forces, following a methodology based on inductive reasoning, supported by a qualitative research strategy and a case study research design. From the documental analysis and the content of semi-structured interviews with eight national specialists (military and civilian) with responsibility in human resources, it was concluded that the Contract Regime is the main source of recruitment for the Permanent Personnel (pillar of stability) and maintains the stability of the personnel, as opposed to the Voluntary Regime, which only exists in the Army. Additionally, the Special Contract Regime offers greater permanence and an increase in technical qualifications. From the request for information to the Defense Attachés at the Embassies of Germany, France, Spain and the United Kingdom, their main tendencies were identified, embodied in short and long-term regimes, characteristics that may be considered in the existing models in the Portuguese Armed Forces.N/

Google matrix analysis of worldwide football mercato

Resumen de la comunicación[EN] The worldwide football transfer market is analyzed as a directed complex network: the football clubs are the network nodes and the directed edges are weighted by the total amount of money transferred from a club to another. The Google matrix description allows to treat every club independently of their richness and allows to measure for a given club the efficiency of player sales and player acquisitions. The PageRank algorithm, developed initially for the World Wide Web, naturally characterizes the ability of a club to import players. The CheiRank algorithm, also developed to analyze large scale directed complex networks, characterizes the ability of a club to export players. The analysis in the two-dimensional PageRank-CheiRank plan permits to determine the transfer balance of the clubs in a more subtle manner than the traditional import-export scheme. We investigate the 2017- 2018 mercato concerning 2296 clubs, 6698 player transfers, and 147 player nationalities. The transfer balance is determined globally for different types of player trades (defender, midfielder, forward, …) and for different national football leagues. Although, on average, the network transfer flows from and to clubs are balanced, the discrimination by player type draws a specific portrait of each football club.Loye, J.; Coquidé, C.; Rollin, G.; Lages, J. (2018). Google matrix analysis of worldwide football mercato. En 2nd International Conference on Advanced Reserach Methods and Analytics (CARMA 2018). Editorial Universitat Politècnica de València. 258-258. https://doi.org/10.4995/CARMA2018.2018.8358OCS25825

Gestão ambiental da Universidade de Brasília : avanços e desafios

Monografia (especialização)—Universidade de Brasília, Faculdade de Economia, Administração e Contabilidade, Departamento de Administração, 2012.Esta monografia analisa os avanços e desafios da Agenda 21 da Universidade de Brasília no campo do desenvolvimento sustentável e avalia o instrumento como documento de referência para promover um novo paradigma focado na gestão ambiental. A integração dos atores sociais envolvidos, que vai além do que está dentro da Instituição, e os incentivos às iniciativas mais verdes nos campi são os grandes desafios para os próximos anos. A falta de compromisso dos gestores e a resistência política de achar que essa é uma “onda ambiental” retardam o modelo de gestão universitária adequada. A pesquisa também sinaliza algumas ações que podem contribuir para o melhoramento das questões ambientais e que perpassam por processos fundamentais como política, gestão e educação ambiental. Conclui-se que investimentos para uma política adequada de gestão ambiental, além de fomentar ações sustentáveis, proporcionam resultados condizentes com a crise ambiental que estamos enfrentando. Outra saída importante seria a elaboração de um regulamento, a ser aprovado pelos colegiados superiores, que permitam a institucionalização de uma política ambiental dentro da Universidade de Brasília. _________________________________________________________________________________ ABSTRACTThis project analyses the advances and challenges of the Agenda 21 at University of Brasilia in the field of sustainable development and evaluates the instrument as a reference document to promote a new paradigm focused on environmental management. The integration of the involved stakeholders which goes beyond what is within the Institution, and green incentives initiatives on campus are the major challenges for the next few years. The lack of commitment of managers and political resistance to think that this is an "environmental wave" inhibits an adequate model of university management. The research also indicates that some of the actions may contribute to the improvement of environmental issues and for fundamental processes that underlie such policies including management and environmental education. We conclude that adequate investments to a policy of environmental management, in addition to promoting sustainable actions, provide results consistent with the environmental crisis we are facing. Another important output would be to build an environmental policy within the University of Brasilia. An important regulation that would have to be approved by higher collegiate

Marketing of Agricultural Products in Alagoas: A Study of Marketing Margins and Price Transmission

This study aims to analyze the empirical results of marketing margins and price transmission of some agricultural products in trade fairs in the state of Alagoas, Brazil. Two agricultural products were used in this study: the curly lettuce and cassava (mandioca). These were sought to differentiate the marketing in various trade fairs in different regions, dividing these into the capital (Maceió and Rio Largo) and interior (Pão de Açúcar and União dos Palmares). The model shows that with the price transmission of the two products tested there is greater difficulty in passing on the producer price for retailers in the capital over the interior. Probably, this indicates that the shorter marketing channel within any influence on this result, for then there is the largest producer of direct participation in the process of formation of the final product price. Moreover, the greater perishability of lettuce influences the results significantly.marketing; marketing margin; transmission price