Hemeroteca del mes agosto, 2013

Maduro puede elegir entre polarizar o ampliar el consenso social

Por • 30 ago, 2013 • Category: Nacionales

Tengo la convicción plena de que un escenario de irracional polarización (aquel de un país artificialmente divido por la mitad) donde no exista mínima comunicación entre los dos grandes polos, es lo que más le conviene a quienes hoy en Venezuela apuestan por el estallido de una guerra civil. Desde ya advierto que sin diálogo, sin espacios de debate ciudadano, sin medios de comunicación que muestren las diferentes visiones del país, sin mecanismos para crear entendimiento ni instrumentos para promover la tolerancia por encima de las discrepancias, es obvio que estaríamos cerrando el camino para la solución constitucional y pacífica de los conflictos.

Science Fiction as a Worldwide Phenomenon: A Study of International Creation, Consumption and Dissemination

Por • 24 ago, 2013 • Category: Ambiente

This paper examines the international nature of science fiction. The focus of this research is to determine whether science fiction is primarily English speaking and Western or global; being created and consumed by people in non-Western, non-English speaking countries? Science fiction’s international presence was found in three ways, by network analysis, by examining a online retailer and with a survey. Condor, a program developed by GalaxyAdvisors was used to determine if science fiction is being talked about by non-English speakers. An analysis of the international Amazon.com websites was done to discover if it was being consumed worldwide. A survey was also conducted to see if people had experience with science fiction. All three research methods revealed similar results. Science fiction was found to be international, with science fiction creators originating in different countries and writing in a host of different languages. English and non-English science fiction was being created and consumed all over the world, not just in the English speaking West.

QED Second Order Corrections on the Speed of Light at Low Temperature

Por • 24 ago, 2013 • Category: Crítica

We want to study thermal corrections on the speed of light at low temperature considering temperature dependence of photon vacuum polarization tensor at two-loop level in the standard QED. It is found that the heat bath behaves as a dispersive medium to the propagation of light and reduces its speed proprtional to the second order of temperature. Similiraties and differences with already known calculations which are based on Euler-Heisenberg Lagrangian and/or those using temperature dependent electromagnetic properties of the medium are discussed.

Towards a mathematical theory of meaningful communication

Por • 24 ago, 2013 • Category: Leyes

Despite its obvious relevance, meaning has been outside most theoretical approaches to information in biology. As a consequence, functional responses based on an appropriate interpretation of signals has been replaced by a probabilistic description of correlations between emitted and received symbols. This assumption leads to potential paradoxes, such as the presence of a maximum information associated to a channel that would actually create completely wrong interpretations of the signals. Game-theoretic models of language evolution use this view of Shannon’s theory, but other approaches considering embodied communicating agents show that the correct (meaningful) match resulting from agent-agent exchanges is always achieved and natural systems obviously solve the problem correctly. How can Shannon’s theory be expanded in such a way that meaning -at least, in its minimal referential form- is properly incorporated?

The Lius of Shanghai: A past ‘Chinese dream’?

Por • 23 ago, 2013 • Category: sociologia

The Lius of Shanghai is based on a lifetime of letters exchanged by the patriarch, Liu Hongsheng, his wife, Ye Suzhen, and their 12 children. Their correspondence offers a fascinating look at how a powerful family navigated the treacherous politics of the period. They discuss sensitive issues – should the family collaborate with the Japanese occupiers, should it flee after the communist takeover? – as well as intimate domestic matters like marital infidelity. They also describe the agonies of wartime separation, protracted battles for control of the family firm, and the parents’ struggle to maintain authority in the face of swiftly changing values. Through it all, the distinctive voices of the Lius shine through, revealing how each of them passionately engaged in family arguments, and at the same time held onto the ties that bound them together.

3D Printing for Math Professors and Their Students

Por • 21 ago, 2013 • Category: Leyes

In this primer, we will describe a number of projects that can be completed with a 3D printer, particularly by mathematics professors and their students. For many of the projects, we will utilize Mathematica to design objects that mathematicians may be interested in printing. Included in the projects that are described is a method to acquire data from an XBox Kinect.

The Ax-Kochen Theorem: an application of model theory to algebra

Por • 21 ago, 2013 • Category: Crítica

The Ax-Kochen Theorem is a purely algebraic statement about the zeros of homogeneous polynomials over the p-adic numbers, but it was originally proved using techniques from mathematical logic. This document, the author’s undergraduate honors thesis, provides an exposition of the theorem and its proof via model theory, assuming no previous experience with logic.

Do the rich get richer? An empirical analysis of the BitCoin transaction network

Por • 21 ago, 2013 • Category: Economía

The possibility to analyze everyday monetary transactions is limited by the scarcity of available data, as this kind of information is usually considered highly sensitive. Present econophysics models are usually employed on presumed random networks of interacting agents, and only macroscopic properties (e.g. the resulting wealth distribution) are compared to real-world data. In this paper, we analyze BitCoin, which is a novel digital currency system, where the complete list of transactions is publicly available. Using this dataset, we reconstruct the network of transactions, and extract the time and amount of each payment. We analyze the structure of the transaction network by measuring network characteristics over time, such as the degree distribution, degree correlations and clustering. We find that linear preferential attachment drives the growth of the network. We also study the dynamics taking place on the transaction network, i.e. the flow of money. We measure temporal patterns and the wealth accumulation. Investigating the microscopic statistics of money movement, we find that sublinear preferential attachment governs the evolution of the wealth distribution. We report a scaling relation between the degree and wealth associated to individual nodes.

Multifractal portrayal of the Swiss population

Por • 21 ago, 2013 • Category: Ambiente

Fractal geometry is a fundamental approach for describing the complex irregularities of the spatial structure of point patterns. The present research characterizes the spatial structure of the Swiss population distribution in the three Swiss geographical regions (Alps, Plateau and Jura) and at the entire country level. These analyses were carried out using fractal and multifractal measures for point patterns, which enabled the estimation of the spatial degree of clustering of a distribution at different scales. The Swiss population dataset is presented on a grid of points and thus it can be modelled as a “point process” where each point is characterized by its spatial location (geometrical support) and a number of inhabitants (measured variable). The fractal characterization was performed by means of the box-counting dimension and the multifractal analysis was conducted through the Renyi’s generalized dimensions and the multifractal spectrum. Results showed that the four population patterns are all multifractals and present different clustering behaviours. Applying multifractal and fractal methods at different geographical regions and at different scales allowed us to quantify and describe the dissimilarities between the four structures and their underlying processes. This paper is the first Swiss geodemographic study applying multifractal methods using high resolution data.

Jacob’s Ladder and Scientific Ontologies

Por • 21 ago, 2013 • Category: Filosofía

The main goal of this article is to use the epistemological framework of a specific version of Cognitive Constructivism to address Piaget’s central problem of knowledge construction, namely, the re-equilibration of cognitive structures. The distinctive objective character of this constructivist framework is based on Heinz von Foerster’s fundamental metaphor of – objects as tokens for eigen-solutions, and is also supported by formal inference methods of Bayesian statistics. This epistemological perspective is illustrated using some episodes in the history of chemistry concerning the definition or identification of chemical elements. Some of von Foerster’s epistemological imperatives provide general guidelines of development and argumentation.