Micro-housing: Seattle’s Contradictory Approach to Affordable, Sustainable Housing

Seattle, along with many other cities, is facing a housing crisis the likes of which it hasn\u27t seen in at least half a century. A lack of affordable housing is exacerbating a homelessness crisis, and is arguably contributing to sprawl. In the face of all of this, Seattle has allowed one of the densest housing options to become economically unfeasible to build at an affordable rate

Los derechos de propiedad en Antigua Guatemala, siglo XIX. Valores liberales en instituciones de Antiguo Régimen

Se aborda la manera como se configuraron los derechos de propiedad en Antigua Guatemala, con base en la hipótesis de que esa municipalidad fue un gobierno que enarboló valores liberales en un marco orgánico de Antiguo Régimen. De igual modo, se estudia cómo el cabildo institucionalizó las prácticas informales que la población tenía sobre la tierra, lo que le daba una ventaja sobre el conjunto de actores racionales que se desenvolvían en esa localidad. El trabajo está fundamentado en el acervo que resguarda el Archivo Histórico de la Ciudad de Antigua Guatemala y cruza el conjunto de patrones encontrados en esa documentación con el planteamiento teórico propuesto por Elinor Ostrom sobre el gobierno de los bienes comunes. A lo largo del texto se observa que el gobierno local, en aras de mantener el control sobre las tierras, promovió de manera indirecta la generación de prácticas asociadas con el liberalismo económico del que, en acciones y discursos, trataban de huir, lo cual derivó en un proceso de perfeccionamiento de la propiedad terso y sin conflictos aparentes

Factorizing the time evolution operator

There is a widespread belief in the quantum physical community, and in textbooks used to teach Quantum Mechanics, that it is a difficult task to apply the time evolution operator Exp{-itH/h} on an initial wave function. That is to say, because the hamiltonian operator generally is the sum of two operators, then it is a difficult task to apply the time evolution operator on an initial wave function f(x,0), for it implies to apply terms operators like (a+b)^n. A possible solution of this problem is to factorize the time evolution operator and then apply successively the individual exponential operator on the initial wave function. However, the exponential operator does not directly factorize, i. e. Exp{a+b} is not equal to Exp{a}Exp{b}. In this work we present a useful procedure for factorizing the time evolution operator when the argument of the exponential is a sum of two operators, which obey specific commutation relations. Then, we apply the exponential operator as an evolution operator for the case of elementary unidimensional potentials, like the particle subject to a constant force and the harmonic oscillator. Also, we argue about an apparent paradox concerning the time evolution operator and non-spreading wave packets addressed previously in the literature.Comment: 24 pages; added references; one figure change

Exact solution of the Schrodinger equation with the spin-boson Hamiltonian

We address the problem of obtaining the exact reduced dynamics of the spin-half (qubit) immersed within the bosonic bath (enviroment). An exact solution of the Schrodinger equation with the paradigmatic spin-boson Hamiltonian is obtained. We believe that this result is a major step ahead and may ultimately contribute to the complete resolution of the problem in question. We also construct the constant of motion for the spin-boson system. In contrast to the standard techniques available within the framework of the open quantum systems theory, our analysis is based on the theory of block operator matrices.Comment: 9 pages, LaTeX, to appear in Journal of Physics A: Mathematical and Theoretica