953 research outputs found

    ‘Cassettes’, networks and banquets. Commercial practices of chinese, taiwanese and argentines in Buenos Aires

    Get PDF
    En este artículo analizaré desde un enfoque etnográfico, las particularidades y dificultades que se presentan al momento de entablar relaciones comerciales entre “chinos”, “taiwaneses” y argentinos. Sostengo que existen diferencias marcadas entre las formas de entablar negocios entre “chinos” y “taiwaneses” desde Argentina. Afirmo que existe una diferencia en los discursos de los especialistas y empresarios argentinos respecto a la importancia del guanxi en las prácticas comerciales, lo que nos daría la pauta de las transformaciones del modo tradicional chino de hacer negocios. En el artículo describo algunas diferencias en la migración “china” y “taiwanesa” en Buenos Aires y los ámbitos empresariales de migrantes y locales así como las maneras en que cada grupo entabla relaciones comerciales con otros, a través de qué tipo de asociaciones y las dificultades que encuentran para entablar relaciones comerciales transnacionales.In this article I analyze from an ethnographic perspective the peculiarities and difficulties that arise in business relationships between “Chinese”, “Taiwanese” and Argentines people. I argue that there are marked differences between the forms of establishing business between “Chinese” and “Taiwanese” in Argentina. I also argue that there are differences in the ideas of Argentine businessmen and experts on China about the relevance of guanxi in business practices, which is linked to the transformations of traditional Chinese ways of doing business. I describe some differences in the “Chinese” and “Taiwanese” migration process in Buenos Aires and the business fields and practices in which these migrants are involved, their associations and transnational business connections.Fil: Denardi, Luciana Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Instituto de Altos Estudios Sociales; Argentin

    Stability analysis and stabilization of linear aperiodic sampled-data systems subject to input constraints

    Get PDF
    Motivados pelo crescente uso de controladores embarcados em diferentes aplicações, onde um protocolo de comunicação é responsável pela transmissão de dados entre algoritmos computacionais, atuadores e sensores, a análise e o controle de sistemas amostrados foram abordados em muitos trabalhos. Nesse contexto, a amostragem aperiódica pode ser vista como uma abstração matemática empregada para representar, na teoria, o efeito de imperfeições no canal de comunicação, como instabilidades, flutuações e, em alguns casos, perda de pacotes de dados. Além disso, devido a limitações físicas dos atuadores, restrições de entrada e, em particular, a saturação são onipresentes em problemas reais de controle. Essas restrições são fonte de comportamentos não-lineares e de degradação do desempenho. Em muitos casos, apenas a estabilidade local (ou regional) do sistema em malha fechada pode ser garantida na presença de restrições e não-linearidades de entrada, mesmo para plantas lineares. Este trabalho lida com sistemas lineares amostrados aperiodicamente em que a entrada de controle, sujeita a restrições (por exemplo, saturação), é calculada com base em uma realimentação de estados do sistema. Dois problemas principais são abordados. O primeiro consiste na análise de estabilidade da origem de tais sistemas com a determinação de estimativas da região de atração da origem (RAO). O segundo, por sua vez, corresponde ao projeto de controle, onde uma lei de controle de realimentação de estados é calculada para otimizar o tamanho de uma estimativa da RAO do sistema em malha fechada resultante. Os métodos propostos são baseados no uso de programação semidefinida ou linear e, portanto, podem ser facilmente aplicados na prática. Um dos métodos propostos considera uma realimentação de estados linear sujeita a saturação e funções de Lyapunov quadráticas, resultando em estimativas elipsoidais da RAO do sistema. Dois outros métodos lidam com a análise de estabilidade do sistema amostrado sujeito a saturação fornecendo estimativas poliedrais da RAO. Devido à sua flexibilidade, a adoção de poliedros em vez de elipsóides permite uma redução de conservadorismo, mas é muito exigente em termos de complexidade computacional. Motivada por esse fato, esta tese também propõe um método de projeto de controle baseado em uma estratégia alternativa, onde a complexidade dos poliedros é fixada a priori. Essa ideia resulta em um problema de otimização com restrições bilineares, onde uma lei de controle linear por partes estabilizadora de complexidade relativamente baixa é encontrada para o sistema amostrado. Os métodos mencionados acima consideram uma abordagem não-estocástica, onde limites inferior e superior são impostos para o intervalo de amostragem do sistema, o qual é desconhecido e variante no tempo. Como contribuição adicional, esta tese também considera uma abordagem estocástica. Um método de projeto de controle é proposto para a estabilização global no sentido quadrático médio do sistema amostrado, onde a lei de realimentação de estados linear é sujeita a não-linearidades que satisfazem a uma condição de setor e os intervalos de amostragem correspondem a variáveis aleatórias com a distribuição de Erlang. A possibilidade de perda de pacotes de dados também é explicitamente levada em consideração através da distribuição de Bernoulli. Além disso, o método proposto, que se baseia na teoria de processos de Markov determinísticos por partes, resulta em condições de estabilização não-conservadoras no caso linear sem restrições de entrada.Motivated by the growing use of embedded controllers in different applications, where a communication protocol is responsible for the transmission of data between computer algorithms, actuators and sensors, the analysis and control design for sampled-data control systems have been addressed in many works. In this context, aperiodic sampling can be seen as a modeling abstraction employed to represent, in a theoretical framework, the effect of imperfections on the communication channel such as sampling jitters, fluctuations and, in some cases, packet dropouts. Moreover, due to physical limitations of actuators, input constraints and, in particular, input saturation are ubiquitous in real control problems. These constraints are source of nonlinear behaviors and performance degradation. In many cases, only local (or regional) stability of the closed-loop system can be ensured in the presence of actuators constraints and nonlinearities, even for linear plants. This work deals with linear aperiodic sampled-data systems where the control input, subject to constraints (e.g. saturation), is computed based on a feedback of the system state. It focuses on two main problems. The first one regards the stability analysis of the origin of such systems, with the determination of estimates of the region of attraction of the origin (RAO). The second one, in turn, corresponds to the control design, where a state-feedback control law is computed in order to enlarge an estimate of the RAO of the resulting closed-loop system. The proposed methods are based on the use of semidefinite or linear programming and can therefore be easily applied in practice. One of the proposed methods considers a linear saturating feedback of the system state and quadratic Lyapunov functions, leading to ellipsoidal estimates of the RAO of the system. Two other methods deal with the stability analysis of the sampled-data system subject to input saturation providing polyhedral estimates of the RAO. Because of their flexibility, adopting polyhedrons instead of ellipsoids allows a reduction of conservatism, but is very demanding in terms of computational complexity. Motivated by this fact, this thesis also proposes a control design method based on an alternative strategy, where the complexity of the polytopes is fixed a priori. This idea results in an optimization problem with bilinear constraints, where a stabilizing piecewise linear control law of relatively low complexity is found for the sampled-data system. The aforementioned methods consider a non-stochastic framework, where lower and upper bounds are imposed for the unknown, time-varying sampling interval of the system. As an additional contribution, this thesis also considers a stochastic setting. A control design method is proposed for the global stabilization in the mean square sense of the sampled-data system, where the linear feedback control law is subject to sector bounded nonlinearities and the sampling intervals are assumed to be random variables with the Erlang distribution. The possibility of packet dropouts is also explicitly taken into account through the Bernoulli distribution. Moreover, the proposed approach, which is based onthe framework of Piecewise Deterministic Markov Processes, leads to non-conservative stabilization conditions in the unconstrained linear case.Motivé par l’utilisation croissante de contrôleurs embarqués dans différentes applications, où un protocole de communication est responsable par la transmission de données entre les algorithmes numériques, les actionneurs et les capteurs, l’analyse et la conception de contrôle pour les systèmes de contrôle échantillonnées ont été abordées dans de nombreux travaux. Dans ce contexte, l’échantillonnage apériodique peut être considéré comme une abstraction mathématique employée pour représenter, dans un cadre théorique, l’effet des imperfections sur le canal de communication telles que la gigue d’échantillonnage, les fluctuations et, dans certains cas, les pertes de paquets. De plus, en raison des limitations physiques des actionneurs, les contraintes d’entrée et, en particulier, la saturation des entrées sont omniprésentes dans les problèmes de contrôle réels. Ces contraintes sont une source de comportements non-linéaires et de dégradation de la performance. Dans de nombreux cas, seule la stabilité locale (ou régionale) du système en boucle fermée peut être assurée en présence de contraintes et de non-linéarités des actionneurs, même pour les systèmes linéaires. Ce travail traite des systèmes linéaires échantillonnées apériodiquement où l’entrée de commande, soumise à des contraintes (par exemple la saturation), est calculée sur la base d’un retour d’état du système. Il se concentre sur deux problèmes principaux. Le premier consiste en l’analyse de stabilité de l’origine de tels systèmes avec la détermination d’estimations de la région d’attraction de l’origine (RAO). Le deuxième, à son tour, correspond à la conception de la commande, où une loi de commande à retour d’état est calculée afin d’agrandir une estimation de la RAO du système en boucle fermée résultant. Les méthodes proposées sont basées sur la programmation semi-définie ou linéaire et peuvent donc être facilement appliquées dans la pratique. L’une des méthodes proposées considère un retour d’état linéaire soumis à la saturation et des fonctions de Lyapunov quadratiques, conduisant à des estimations ellipsoïdales de la RAO du système. Deux autres méthodes traitent de l’analyse de stabilité du système échantillonné soumis à la saturation des entrées fournissant des estimations polyédriques de la RAO. En raison de leur flexibilité, l’adoption de polyèdres au lieu d’ellipsoïdes permet une réduction du conservatisme mais est très exigeante en termes de complexité de calcul. Motivée par ce fait, cette thèse propose également une méthode de conception de contrôle basée sur une stratégie alternative, où la complexité des polyèdres est fixée a priori. Cette idée se traduit par un problème d’optimisation avec des contraintes bilinéaires, où une loi de commande linéaire par morceaux stabilisante de complexité relativement faible est trouvée pour le système échantillonné. Les méthodes mentionnées ci-dessus considèrent un cadre non stochastique, où des limites inférieure et supérieure sont imposées pour l’intervalle d’échantillonnage inconnu et variable dans le temps du système. Comme contribution supplémentaire, cette thèseconsidère également un cadre stochastique. Une méthode de conception de contrôle est proposée pour la stabilisation globale dans le sens quadratique moyen du système échantillonné, où la loi de contrôle linéaire de retour d’état est soumise à des non-linéarités délimitées par secteur et les intervalles d’échantillonnage sont supposés être des variables aléatoires avec la distribution d’Erlang. La possibilité de pertes de paquets est aussi explicitement prise en compte via la distribution de Bernoulli. De plus, l’approche proposée, qui est basée sur le cadre des processus de Markov déterministes par morceaux, conduit à des conditions de stabilisation non conservatrices dans le cas linéaire sans contraintes

    Etnografía de una experiencia educativa alternativa: la educación popular en un Centro Educativo Complementario del Gran Buenos Aires

    Get PDF
    En este trabajo intentaremos dar cuenta de las actividades realizadas en un Centro Educativo Complementario (CEC) en clave de Educación Popular de una escuela católica y privada de la localidad de González Catán, en la provincia de Buenos Aires, Argentina. Esta institución está atravesando un proceso de redefinición de sus destinatarios, por lo cual analizaré los cambios que se producen al respecto a nivel administrativo, organizativo, docente y curricular, para finalmente presentar los tipos de conflictos que se producen entre los agentes escolares, especialmente los docentes, a raíz de estos cambios.This paper analyzes the activities performed in a Complementary Educational Center (CEC) of a private Catholic school in Gonzalez Catán, province of Buenos Aires, Argentina. The institution educational project is inspired in Paulo Freire´s popular education and is redefining its receivers. In this article I will present the changes on the following levels: administrative, organizational, educational and curriculum. Finally, I will analyze the types of conflicts that occur among school agents, especially teachers, as a result of that redefinition.Fil: Denardi, Luciana Emilia. Universidad Nacional de San Martín. Instituto de Altos Estudios Sociales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Wealth Inequality and Intergenerational Links

    Get PDF
    Empirical studies have shown that, for many countries, the distribution of wealth is much more concentrated than the one of labor earnings and that households with higher levels of lifetime income have higher lifetime saving rates. Previous models have had difficulty in generating these features. I construct a computable general equilibrium model with overlapping generations in which parents and children are linked by bequests and earnings persistence within families. I show that voluntary bequests are important to explain the emergence of large estates that characterize the top of the wealth distribution, while accidental bequests are not. In addition, the introduction of a bequest motive generates lifetime saving profiles more consistent with the data. Allowing for earnings persistence within families generates an even more concentrated wealth distribution. A cross-country comparison between the U.S. and Sweden shows that intergenerational linkages are important to explain the upper tail of the wealth distribution also in economies where redistribution programs are more prominent and there is less inequality. Moreover Sweden, with its generous social safety net, has a larger fraction of people with zero or negative wealth. The model is capable of reproducing this feature as well.

    Covid-19 and Digital Anti-Sinophobia in Argentina

    Get PDF
    While racial discrimination against people of Asian and particularly Chinese origin is well-understood in the Global North, its dynamics in the Global South remain under-investigated. Moreover, although Covid-19 contributed significantly to the reinforcement of sinophobic stereotypes around the globe, recent research has barely paid any attention to new forms of counter-reaction, such as those that evolve in digital channels, especially in Latin America. This paper sheds light on anti-Asian racism and the digitized counter-reactions of Chinese migrants before and after Covid-19 in the crucial case of Argentina. In the past, these migrants mostly remained silent when confronted with institutional racism. However, it was precisely the outbreak of Covid-19 that contributed to the creation of new forms of empowerment on online platforms by this racialized minority and that allowed them to present their demands to state agencies and to denounce sinophobic debates on social media. Methodologically, this study combines elements of process-tracing with both traditional and online ethnographic methods to explain these trickle-up effects

    Flying together towards EFL teacher development as language learners and professionals through genre writing

    Get PDF
    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Letras/Inglês e Literatura Correspondente, Florianópolis, 2009This qualitative study on the inter-relation between English as a Foreign Language Teacher Education (EFLTE) and the teaching of writing follows, mainly, the theoretical-methodological approach of Socio-discursive Interactionism (Bronckart, 2003, 2006, 2008a and his followers). Its general objective is to investigate in what aspects and to what extent an interventionist practice concerning the teaching of writing can contribute to EFL teachers development as language learners and professionals. Specifically, the aims of this study are: a) to identify which elements related to the language capacities of action, discursive and linguistic-discursive can be taught for the writing of an academic summary (AS); b) to investigate in what aspects and to what extent the process of writing an AS by means of a didactic sequence (DS) can contribute to teachers development; c) to investigate in what aspects and to what extent the process of planning a DS to the teaching of writing of specific genres can contribute to the teachers' development; and d) to investigate which individual representations were constructed during the processes of writing an AS and planning DS for the teaching of writing specific genres. Four main sets of data are analyzed: a corpus of ten ASs produced by the participant-teachers of an EFLTE course, participant-teachers DS plans, and participant-teachers direct self-confrontation texts. The results of the analysis of each set of data reveals that: 1) the elements related to the three language capacities to be studied for writing an AS should be: the thematic content and context of production of the academic article, descriptive type of sequence and theoretical type of discourse, affirmative sentences, present simple tense and present passive, nominal group, nominal and pronominal anaphora, logic modalization, connectors and reporting verbs; 2) the participants substantially developed as language learners, since they made considerable progress in the three language capacities from the first to the last AS versions; 3) the participants knowledge development related to the three language capacities in the task of planning DSs was partially adequate. Crossing the results from the second and third sets of data with the teaching knowledge base dimensions (Richards, 1998), named Theories of Teaching, Teaching Skills, Communication Skills, Pedagogical Knowledge Skills and Decision Making and Contextual Knowledge reveals that the participants developed in the six dimensions; 4) the participants also developed in the reflective dimensions named Epistemological, Ontological, Pedagogical, Linguistic and Axiological. The overall findings, therefore, reveal that a genre-based perspective for the teaching of writing through the use of the procedure of DS can be seen as an adequate theoretical, methodological and reflexive mechanism for EFLTE.Este estudo qualitativo sobre a inter-relação entre formação de professores de inglês como língua estrangeira e ensino de escrita segue, principalmente, a abordagem teórico-metodológica do Interacionismo Sociodiscursivo (Bronckart, 2003; 2006; 2008a e seus seguidores). Seu objetivo geral é investigar em que aspectos e até que ponto uma prática intervencionista relacionada ao ensino de escrita pode contribuir no desenvolvimento de professores de Inglês como língua estrangeira como aprendizes e profissionais. Especificamente, este estudo objetiva: a) identificar quais elementos relacionados às capacidades de linguagem de ação, discursiva e lingüístico-discursiva podem ser ensinados na escrita de um resumo acadêmico (RA); b) investigar de que forma e até que ponto o processo de escrita de um RA através do procedimento de sequência didática (SD) pode contribuir para o desenvolvimento de professores; c) investigar de que forma e até que ponto o processo de planejamento de uma SD para o ensino de escrita pode contribuir para o desenvolvimento de professores; e d) investigar que representações individuais foram construídas durante o processo de escrita de um RA e planejamento de uma SD para ensino de escrita de gêneros específicos. Quatro conjuntos de dados são analisados: um corpus de dez RAs, resumos acadêmicos produzidos por professores de inglês participantes de um curso de formação continuada, planos de SD dos professores participantes, e textos de auto-confrontação simples dos participantes. Os resultados da análise de cada conjunto de dados mostram que: 1) os elementos, relacionados às três capacidades de linguagem, a serem estudados na escrita de RAs devem ser: o conteúdo temático e o contexto de produção do artigo acadêmico, tipo de sequência descritiva e tipo de discurso teórico, orações afirmativas, presente simples e voz passiva no presente, grupo nominal e anáfora nominal e pronominal, modalização lógica, conectores e verbos de dizer; 2) os participantes se desenvolveram substancialmente como aprendizes da língua inglesa, pois progrediram consideravelmente nas três capacidades de linguagem da primeira à última versão dos RAs; 3) o desenvolvimento dos participantes com relação às três capacidades de linguagem na tarefa de planejamento de SDs foi parcialmente adequado. O cruzamento dos dados do segundo e terceiro conjuntos com as seis dimensões básicas de conhecimento de ensino (Richards, 1998), nomeadamente, Teorias de Ensino, Habilidades de Ensino, Habilidades de Comunicação, Habilidades Pedagógicas e Poder de Decisão e Conhecimento do Contexto revela que os participantes se desenvolveram nas seis dimensões; 4) os participantes também se desenvolveram nas dimensões reflexivas Epistemológica, Ontológica, Pedagógica, Linguística e Axiológica. Os resultados gerais deste estudo revelam que uma perspectiva de ensino de escrita baseada em gêneros textuais através do procedimento de SD pode ser um mecanismo teórico, metodológico e reflexivo adequado para o desenvolvimento de professores de inglês como língua estrangeira

    Covid-19 and Digital Anti-Sinophobia in Argentina

    Get PDF
    While racial discrimination against people of Asian and particularly Chinese origin is well-understood in the Global North, its dynamics in the Global South remain under-investigated. Moreover, although Covid-19 contributed significantly to the reinforcement of sinophobic stereotypes around the globe, recent research has barely paid any attention to new forms of counter-reaction, such as those that evolve in digital channels, especially in Latin America. This paper sheds light on anti-Asian racism and the digitized counter-reactions of Chinese migrants before and after Covid-19 in the crucial case of Argentina. In the past, these migrants mostly remained silent when confronted with institutional racism. However, it was precisely the outbreak of Covid-19 that contributed to the creation of new forms of empowerment on online platforms by this racialized minority and that allowed them to present their demands to state agencies and to denounce sinophobic debates on social media. Methodologically, this study combines elements of process-tracing with both traditional and online ethnographic methods to explain these trickle-up effects.Fil: Baumann, Clara. Universitat Essen; Alemania. International Max Planck Research School on the Social and Political Constitution of the Economy; AlemaniaFil: Denardi, Luciana Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Instituto de Altos Estudios Sociales; Argentin

    Entrepreneurship, Bequests, and the Distribution of Wealth

    Get PDF
    Entrepreneurs hold a significant fraction of the total wealth in the economy; they are approximately 8% of the population but hold 39% of total net worth. In this paper, we construct and solve numerically a life cycle optimization model with intergenerational transmission of bequests to study the choice of starting an entrepreneurial activity, and its effect on the wealth accumulation of entrepreneurs and on the distribution of wealth in the population. We examine two forces that determine self selection into an entrepreneurial activity: initial wealth and attitudes to risk. Starting a business requires initial funds, and entrepreneurs may have to invest part of their own wealth into the business activity. Some of this initial funds may come from parental transfers and bequests. Entrepreneurial income has higher return, but is riskier than labor income: more risk averse households may decide not to become entrepreneurs, despite the expected gains from such activity. We calibrate our model to the US economy. We find that the possibility of an entrepreneurial activity increases by 50% the fraction of wealth held by the top 1%. We also show that increasing the coefficient of risk aversion significantly decreases the percentage of entrepreneurs, and even in the absence of initial funding requirements, we cannot match the percentage of 8.6% of entrepreneurs. We also study the effects of changes in the initial funding requirements and in the degree of intergenerational altruism.

    ANATOMIA ECOLÓGICA DA MADEIRA DE Blepharocalyx salicifolius (H. B. K.) Berg

    Get PDF
    RESUMO O presente trabalho visa à comparação anatômica da madeira da murta Blepharocalyx salicifolius (H. B. K.) Berg (Myrtaceae), em duas regiões do Rio Grande do Sul. Foram coletados seis exemplares da espécie; três na região da Serra do Sudeste e os demais nos Campos de Cima da Serra. Qualitativamente, a madeira não revelou diferenças expressivas entre as procedências, exceto pela presença de máculas medulares. Sob o ponto de vista de suas características quantitativas, foram encontradas diferenças importantes na estrutura de vasos, parênquima axial, raios e fibras. As amostras da “Serra do Sudeste” mostraram características xéricas no lenho: poros numerosos e pequenos, além de elementos vasculares e fibras de comprimento menor, diferentemente das amostras dos “Campos de Cima da Serra”. Quanto ao índice de vulnerabilidade, não foi encontrada diferença significativa entre as procedências. As alterações verificadas no lenho podem ser interpretadas como resposta adaptativa da espécie aos respectivos ambientes

    Ser chino en Buenos Aires

    Get PDF
    Este artículo se propone realizar una descripción de las particularidades de la comunidad china y taiwanesa en Buenos Aires. Recorre la historia de la migración china y taiwanesa hacia Argentina y los cambios que se están registrando en los últimos años, con la nueva posición de China en la economía mundial. Proponemos que la diáspora china y taiwanesa pueden ser pensadas como “puentes”, ya que los taiwaneses se re identifican como “chinos” alegando una pertenencia ancestral al legado cultural chino, y los chinos continentales están ocupando el lugar asignado por el estado chino para sus diásporas: ser un eslabón en el proceso de expansión económica chino, intermediando entre la sociedad de recepción y la madre patria.This article proposes a description of the peculiarities of Chinese and Taiwanese community in Buenos Aires. It traces the history of Chinese and Taiwanese migration to Argentina and the changes that are occurring in recent years, with the new position of China in the world economy. We propose that the Chinese and Taiwanese diaspora can be understood of as “bridges”, since Taiwanese re identify themselves as “Chinese” because off a cultural belonging to a Chinese legacy, and mainland Chinese are taking the place assigned by the Chinese state to their diasporas: be a link in the process of Chinese economic expansion, mediating between the receiving society and the motherland
    corecore