Dynamical properties of a particle in a wave packet: scaling invariance and boundary crisis

Some dynamical properties present in a problem concerning the acceleration of particles in a wave packet are studied. The dynamics of the model is described in terms of a two-dimensional area preserving map. We show that the phase space is mixed in the sense that there are regular and chaotic regions coexisting. We use a connection with the standard map in order to find the position of the first invariant spanning curve which borders the chaotic sea. We find that the position of the first invariant spanning curve increases as a power of the control parameter with the exponent 2/3. The standard deviation of the kinetic energy of an ensemble of initial conditions obeys a power law as a function of time, and saturates after some crossover. Scaling formalism is used in order to characterize the chaotic region close to the transition from integrability to nonintegrability and a relationship between the power law exponents is derived. The formalism can be applied in many different systems with mixed phase space. Then, dissipation is introduced into the model and therefore the property of area preservation is broken, and consequently attractors are observed. We show that after a small change of the dissipation, the chaotic attractor as well as its basin of attraction are destroyed, thus leading the system to experience a boundary crisis. The transient after the crisis follows a power law with exponent -2.Comment: Chaos, Solitons & Fractals, 201

Inequality, ability to pay and the theories of equal and proportional sacrifices

Brazil has one of the worst distributions of income in the world. The wealth of the richest 1% of the population is equal to that of the poorest 50%. Brazil has a greater concentration of wealth than ninety-five percent of the countries on which data is available. In the legal field, tax justice is based on the constitutional principle of the “ability to pay”, according to which taxes should be paid based on the economic capacity of the taxpayer. This principle first appeared in the Brazilian legal order in the 1946 Constitution, was excluded from the texts of 1967/69, and reappeared in § 1 of article 145 of the 1988 Constitution. The aim of this paper is to examine two possible grounds for the ability to pay principle (equal sacrifices and proportional sacrifices) to show how, in Brazil, the interpretations that seek to assign a positive content to the principle are limited to the horizons of a particular form of State associated with the theory of equal sacrifice. This theory for its turn is consistent with a theory of justice, under which no expense or charge levied by the government can alter the distribution of welfare produced by the market. As the application of the ability to pay principle is done within the limits of that horizon, as a consequence, this principle does not play an important role in the issue of reduction of inequality in Brazil

CARTOGRAFÍAS DEL YO. ESCRITURA AUTOBIOGRÁFICA Y MODERNIDAD EN CENTROAMÉRICA, DEL MODERNISMO AL TESTIMONIO.

This dissertation examines some canonical Central American autobiographical works of the 20th Century. The authors studied include Rubén Darío, Rafael Arévalo Martínez, Froylán Turcios, José Coronel Urtecho, César Brañas, Eunice Odio, Roque Dalton, Miguel Mármol and Rigoberta Menchú. The dissertation maintains that autobiographical writing always interpellates the Other's story and that this interpellation is based in the need to incorporate into modern discourse the social sectors considered "pre-modern." Indigenous people, peasants, women, artisans and workers, oral or illiterate cultures, represent a zone of autobiographical fear and desire. These combined impulses are connected to some cultural peculiarities of the Central American region: mainly, the way in which the rhetoric and practice of Liberalism is adapted by the regional elites from the end of 19th Century onward.After a general overview offered in Chapter 1, this dissertation is divided in three parts that correspond to three different cultural epochs—Modernismo (Chapters 2, 3, 4), Vanguardia (Chapters 5 and 6), and Postvanguardia y testimonio (Chapters 7 y 8). In Modernista autobiography the class-racial-ethnic Other appears as something that "haunts" the traditional, representing both an object of fear and a limit to a Eurocentric concept of modernity. In contrast, the Vanguardista autobiography emphasized its desire of the Other. This general desires for "incorporate" the (national) Other is linked to the foundational /nationalist emphasis that the avant-garde showed in Central America. However, Liberalism never incorporated fully the utopian social models of the Vanguardistas. Due to the crisis of both the Liberal rhetoric and Vanguardista cultural projects, during the 1960s and 1980s the aesthetic-ideological project of the Vanguardia suffered a radicalization. One of the main outcomes was the popularization of testimonio, which has become the most analyzed form of Central American autobiographical writing today. In testimonio the Other and his/her cultural model (basically, orality) and the Gemeinschaft of rural community become embodied as a counter-hegemonic voice that seeks to interpellate the cultural models of the "lettered city" and modernity from a subaltern location

iLRN 2018 Main Conference Preface

iLRN 2018. Conferência realizada em Missoula, MT, USA, de 24-29 de junho de 2018.ILRN 2018 was the fourth annual international conference of the Immersive Learning Network. It followed on from the inaugural conference held in Prague in July 2015, the second conference held in Santa Barbara in June 2016, and the third conference held in Coimbra, Portugal, in 2017. In response to the increasingly accessible and powerful range of VR and AR technology, the vision of the iLRN is to develop a comprehensive research and outreach agenda that encompasses the breadth and scope of learning potentialities, affordances, and challenges of immersive learning environments. To achieve this, the iLRN invites and hosts scientists, practitioners, organizations, and innovators across many disciplines to explore, describe, and apply the optimal use of immersive worlds and environments for educational purposes. The annual conference aims to explain and demonstrate how these immersive learning environments best work. In 2018, 21 formal papers were received for the main conference and after a rigorous reviewing process six were selected for this Springer publication (28% acceptance rate). The authors of these papers come from institutions located in Brazil, Germany, the UK, and the USA (Florida, Texas, California). The main conference papers cover a range of interesting topics in some depth, providing useful information for other educators and researchers. Alvarez-Molina et al. report on how video games can help players develop their musical skills and illustrate this by creating and evaluating a music-video game that aims to improve the key skill of pitch recognition. Bakri et al. investigate the subjective perception of the fidelity of 3D cultural heritage artifacts on the Web and how this affects the user experience. De León reports on the promising results of utilizing problem-based learning for bridging theory and practice in teacher preparation programs through the use of immersive, ill-structured problems in a multi-user virtual environment that simulates a real school. Feenan draws upon 10 years of studies into the use of digital game-based learning as the basis of an analysis that recommends a five-pronged approach to the successful use of games to support social resiliency skills for students in a fast-changing world. Johnson and Sullivan describe a pilot study that identifies three key strategies for making students feel more comfortable and productive in an experimental game design class. Queiroz et al. present a literature review of learning outcomes from using fully HMD-based IVE in primary/K-12 education, highlighting relevant studies, identifying gaps, and providing insights for use in further research. This informative and fascinating collection of papers reflects the emerging and valuable possibilities of immersive learning research. We know you will find many points of interest and use in the well-presented reports in this collection. Finally, we strongly encourage you to join ILRN and contribute your own insights and research to the community.info:eu-repo/semantics/publishedVersio

A version of the random directed forest and its convergence to the Brownian web

Several authors have studied convergence in distribution to the Brownian web under diffusive scaling of Markovian random walks. In a paper by R. Roy, K. Saha and A. Sarkar, convergence to the Brownian web is proved for a system of coalescing random paths - the Random Directed Forest- which are not Markovian. Paths in the Random Directed Forest do not cross each other before coalescence. Here we study a generalization of the non-Markovian Random Directed Forest where paths can cross each other and prove convergence to the Brownian web. This provides an example of how the techniques to prove convergence to the Brownian web for systems allowing crossings can be applied to non-Markovian systems

Nuclear dimension and Z-stability of non-simple C*-algebras

We investigate the interplay of the following regularity properties for non-simple C*-algebras: finite nuclear dimension, Z-stability, and algebraic regularity in the Cuntz semigroup. We show that finite nuclear dimension implies algebraic regularity in the Cuntz semigroup, provided that known type I obstructions are avoided. We demonstrate how finite nuclear dimension can be used to study the structure of the central sequence algebra, by factorizing the identity map on the central sequence algebra, in a manner resembling the factorization arising in the definition of nuclear dimension. Results about the central sequence algebra are used to attack the conjecture that finite nuclear dimension implies Z-stability, for sufficiently non-type I, separable C*-algebras. We prove this conjecture in the following cases: (i) the C*-algebra has no purely infinite subquotients and its primitive ideal space has a basis of compact open sets, (ii) the C*-algebra has no purely infinite quotients and its primitive ideal space is Hausdorff. In particular, this covers C*-algebras with finite decomposition rank and real rank zero. Our results hold more generally for C*-algebras with locally finite nuclear dimension which are (M,N)-pure (a regularity condition of the Cuntz semigroup).Comment: Rewrote abstract and introduction. Added a couple of results. Main results unchange