Three types of shopping precincts. Three different ways to influence the public sphere of neighborhoods

Indexación: Scopus.Considerando que en la teoría urbana el mercado y los espacios públicos están históricamente vinculados, este artículo analiza un mercado, una galería comercial y un centro comercial (mall). El fin es ilustrar los factores que son determinantes para que en Santiago de Chile estas tipologías de comercio adquieran carácter público y puedan contribuir a la esfera pública de la ciudad, al menos dentro de las limitaciones que se derivan de su condición privada. Hasta ahora el debate ha reflexionado extensivamente sobre estas tres tipologías, sin embargo, existen aún pocos estudios que miran la vida pública que tiene lugar en estas diferentes tipologías de manera paralela, considerando que hoy todas ellas están presentes simultáneamente en la ciudad y se disputan su espacio en ella. Esta investigación describe características físicoespaciales y de administración de estos tres casos para aportar a las políticas públicas y el diseño urbano. Se estudia el comercio en relación a la accesibilidad a nivel metropolitano y en cuanto a los diferentes tipos de comercio, que pretenden atraer un público diverso y promueven el carácter público de los espacios.According to urban theory, commerce and public spaces are historically related to each other. Based on this premise, this paper analyzes a market, a shopping center and a mall. The goal of this research is to identify the key factors that turn these shopping precincts into public spaces and contribute to the public sphere in Santiago, Chile, at least within the context of the limitations associated with their private nature. To date, these three typologies have been the focus of intense debate. However, there are few studies of the public life that takes place in these spaces, especially when considering that they coexist simultaneously in the city, claiming a space within it. This research describes the physical-spatial and administrative characteristics of these three cases in order to contribute to the strengthening of public policies in urban design. Likewise, commerce is studied in relation to accessibility patterns at metropolitan level and the types of markets that aim to attract different users and promote the public nature of these spaces.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-83582018000100089&lng=en&nrm=iso&tlng=e

Variational principle and energy-momentum tensor for relativistic Electrodynamics of point charges

We give a new representation as tempered distribution for the energy-momentum tensor of a system of charged point-particles, which is free from divergent self-interactions, manifestly Lorentz-invariant and symmetric, and conserved. We present a covariant action for this system, that gives rise to the known Lorentz-Dirac equations for the particles and entails, via Noether theorem, this energy-momentum tensor. Our action is obtained from the standard action for classical Electrodynamics, by means of a new Lorentz-invariant regularization procedure, followed by a renormalization. The method introduced here extends naturally to charged p-branes and arbitrary dimensions.Comment: 36 pages, no figures, refs. and comments adde

Cutting through Content Clutter: How Speech and Image Acts Drive Consumer Sharing of Social Media Brand Messages

Consumer-to-consumer brand message sharing is pivotal for effective social media marketing. Even as companies join social media conversations and generate millions of brand messages, it remains unclear what, how, and when brand messages stand out and prompt sharing by consumers. With a conceptual extension of speech act theory, this study offers a granular assessment of brands’ message intentions (i.e., assertive, expressive, or directive) and the effects on consumer sharing. A text mining study of more than two years of Facebook posts and Twitter tweets by well-known consumer brands empirically demonstrates the impacts of distinct message intentions on consumers’ message sharing. Specifically, the use of rhetorical styles (alliteration and repetitions) and cross-message compositions enhance consumer message sharing. As a further extension, an image-based study demonstrates that the presence of visuals, or so-called image acts, increases the ability to account for message sharing. The findings explicate brand message sharing by consumers and thus offer guidance to content managers for developing more effective conversational strategies in social media marketing

Analysis and optimization of propagation losses in LiNbO3 optical waveguides produced by swift heavy-ion irradiation

The propagation losses (PL) of lithium niobate optical planar waveguides fabricated by swift heavy-ion irradiation (SHI), an alternative to conventional ion implantation, have been investigated and optimized. For waveguide fabrication, congruently melting LiNbO3 substrates were irradiated with F ions at 20 MeV or 30 MeV and fluences in the range 1013–1014 cm−2. The influence of the temperature and time of post-irradiation annealing treatments has been systematically studied. Optimum propagation losses lower than 0.5 dB/cm have been obtained for both TE and TM modes, after a two-stage annealing treatment at 350 and 375∘C. Possible loss mechanisms are discussed

Building extended resolvent of heat operator via twisting transformations

Twisting transformations for the heat operator are introduced. They are used, at the same time, to superimpose a` la Darboux N solitons to a generic smooth, decaying at infinity, potential and to generate the corresponding Jost solutions. These twisting operators are also used to study the existence of the related extended resolvent. Existence and uniqueness of the extended resolvent in the case of $N$ solitons with N "ingoing" rays and one "outgoing" ray is studied in details.Comment: 15 pages, 2 figure

A Computational Channel Model for Magnetic Induction-Based Subsurface Applications

There are many underground applications based on magnetic fields generated by an oscillating magnetic source. For them, a magnetic dipole in a three-layered region with upper semi-infinite air layer can be a convenient idealization used for their planning, development, and operation. Solutions are in the form of the well-known Sommerfeld integral expressions that can be evaluated by numerical methods. A set of field expressions to be numerically evaluated by an efficient algorithm are not collected comprehensively yet, or at least in a directly usable form. In this paper, the explicit magnetic field solutions for the vertical magnetic dipole and the horizontal magnetic dipole for a general source-observer location are derived from the Hertz vector. They can be properly combined to model the problem of a tilted magnetic dipole source for horizontally or inclined stratified media. As a result, a complete set of integral equations of the Sommerfeld type valid from the near zone to the far zone are formulated. A method for numerical evaluation of the field expressions for high accurate computations is described. The numerical results are validated using the finite element method for all the possible source-receiver configurations and three well-spanned frequencies of typical subsurface applications. Both numerical solutions agree according to the normalized root-mean-square error-based fit metric. Numerical results for two cases of study are presented to see its usefulness for subsurface applications. A MATLAB implementation of the mathematical description outlined in this paper and the proposed evaluation method is freely available for download

Dispersionless limit of the noncommutative potential KP hierarchy and solutions of the pseudodual chiral model in 2+1 dimensions

The usual dispersionless limit of the KP hierarchy does not work in the case where the dependent variable has values in a noncommutative (e.g. matrix) algebra. Passing over to the potential KP hierarchy, there is a corresponding scaling limit in the noncommutative case, which turns out to be the hierarchy of a `pseudodual chiral model' in 2+1 dimensions (`pseudodual' to a hierarchy extending Ward's (modified) integrable chiral model). Applying the scaling procedure to a method generating exact solutions of a matrix (potential) KP hierarchy from solutions of a matrix linear heat hierarchy, leads to a corresponding method that generates exact solutions of the matrix dispersionless potential KP hierarchy, i.e. the pseudodual chiral model hierarchy. We use this result to construct classes of exact solutions of the su(m) pseudodual chiral model in 2+1 dimensions, including various multiple lump configurations.Comment: 37 pages, 10 figures, 2nd version: some extensions (Fig 3, Appendix A, additional references), 3rd version: some minor changes, additional reference