New Gilded Age or Old Normal?

Since the mid-1970s, inequality has increased under Democratic as well as Republican administrations and Congresses. In retrospect, the four and a half decades from 1933 to 1978 were a historical aberration. The longer-term trend toward more inequality in capitalist economies, which prevailed before this period, has re­sumed after it. That leads us to conclude that there may well be no technocratic or tax policy fix for capitalism’s tendency to generate ever more inequality

Electron correlations, spontaneous magnetization and momentum density in quantum dots

The magnetization of quantum dots is discussed in terms of a relatively simple but exactly solvable model Hamiltonian. The model predicts oscillations in spin polarization as a function of dot radius for a fixed electron density. These oscillations in magnetization are shown to yield distinct signature in the momentum density of the electron gas, suggesting the usefulness of momentum resolved spectroscopies for investigating the magnetization of dot systems. We also present variational quantum Monte Carlo calculations on a square dot containing 12 electrons in order to gain insight into correlation effects on the interactions between like and unlike spins in a quantum dot.Comment: 6 pages, 4 figure

Diagnóstico de los Niveles I: Acercar y II: Promoción de la producción y el consumo sostenible, del Programa de Gestión Ambiental Empresarial en Bogotá D.C.

(Eng) Evaluation and feedback are essential in all management processes, especially when actions are aimed at target level of a local authority, especially as complex as a capital district. This document presents the main findings of the diagnosis that was made in Levels I and II of the Environmental Business Management Program (GAE by its acronym in spanish) in Bogota. For its development, management reports generated by the Secretaría Distrital de Ambiente (SDA) were consulted, and the approach of the actions in levels I and II quantitatively and qualitatively were evaluated. On the other hand, surveys were formulated and applied to both participating and external companies, the first ones, in spaces of the GAE Program, provided by the SDA, and the second through visits, phone calls and electronic mails. The analysis and processing of these data allowed us to establish the impact of levels I and II of the GAE Program on the perception, support and management of Cleaner Production (CP) and Sustainable Consumption (SC) in companies grounded in Bogota, the Capital District. Finally, based on the above, as well as in consultations with external entities, the recommendations for the planning and execution in order to contribute to the continuous improvement in the promotion of CP and SC in the productive sector were made.(Spa) La evaluación y la retroalimentación son fundamentales en todos los procesos de gestión, aún más cuando están dirigidos a orientar actuaciones a nivel de un ente territorial, especialmente tan complejo como lo es un Distrito Capital. El presente documento expone los principales hallazgos del diagnóstico que se realizó en los niveles I y II del Programa de Gestión Ambiental Empresarial (GAE) en la ciudad de Bogotá. Para su desarrollo, se consultaron los informes de gestión generados por la Secretaría Distrital de Ambiente (SDA) y se evaluaron cuantitativa y cualitativamente los planteamientos de las acciones consideradas en los niveles I y II. Por otra parte, se formularon y aplicaron encuestas tanto a empresas participantes como empresas externas, las primeras, en espacios propios del Programa GAE, facilitados por la SDA y las segundas a través de visitas, llamadas y correos electrónicos. El análisis y procesamiento de estos datos permitió establecer el impacto que han tenido los niveles I y II del Programa GAE en la percepción, el apoyo y la gestión de la Producción Más Limpia (PML) y Consumo Sostenible (CS) en las empresas con sede en Bogotá, Distrito Capital. Finalmente, basado en lo anterior, así como en consultas en entes externos, se formularon las recomendaciones pertinentes para la planeación y la ejecución con el fin de contribuir a la mejora continua en el fomento de la PML y CS en el sector productivo

Modelo fenomenológico para escalar a yacimiento el impacto sobre producción de hidrocarburos del daño de formación por migración de finos

El objeto del artículo consiste en proponer y resolver un modelo de bases fenomenológicas que permite caracterizar, cuantificar y pronosticar el daño de formación por migración de finos e hinchamiento de arcillas a escala de yacimiento a partir del esquema metodológico matemático lineal de Civan [1]. El proceso de entendimiento del fenómeno de partículas en un medio poroso ha sido abordado en la mayoría de los casos desde la perspectiva del laboratorio, medición de tasas críticas en núcleos de formación y con base en estas se han generado modelos matemáticos para simular los fenómenos de partícula bajo condiciones de laboratorio. Se construye, se propone, se aplica y se valida una metodología para trascender y escalar hasta la escala de yacimiento los resultados de pruebas de daño de formación por flujo de finos observados en laboratorio. La metodología generada se basa en desarrollar pruebas de desplazamiento multi tasa de una suspensión de material fino, resolver y  aracterizar el daño por flujo de partículas en el núcleo en función de la velocidad con el modelo lineal de Civan, construir y resolver el modelo para estimar los perfiles de daño en función del radio, validar el esquema con datos de campo para estimar el impacto del daño y el radio crítico para un pozo productor. Actualmente más del 50% de los campos operados por Ecopetrol presentan daño de formación por procesos de partícula, la cantidad de petróleo que se deja de producir por este fenómeno se estima en miles de barriles, con una aproximación de este tipo se puede diseñar y optimizar los tratamientos requeridos para mitigar el daño y recuperar un porcentaje significativo de los barriles que no se pueden producir. En este proyecto se muestra el proceso usando datos de la formación Barco del campo Cupiagua, el escalamiento indica caídas de permeabilidad del 65% por este tipo de daño, radios de daño entre 1.9 y 4.4 ft y valor “skin” de daño por finos entre 1.9 y 3.4. Este proceso permitió generar diseños de los tratamientos de estimulación para este campo. The objective of the article consists in proposing and solving a model of the phenomenological bases that allows characterize, quantify and predict the formation damage due fines migration and swelling clays at reservoir level from the linear mathematical methodological scheme Civan [1]. The process of understanding the phenomenon of particles on a porous medium has been for the most cases approach from the laboratory perspective, measuring the critical rates of the formation plugs and based on this it’s had been generated a mathematical model for the simulation of the particle phenomenon by laboratory conditions. It’s construct, it’s propose, it’s applied and it’s validate a methodology for transcending and scale to the reservoir scale the results of the formation damage by the flow of fines observed in the laboratory. The generated methodology is base in performing multi-rate coreflooding tests, solve and characterize the damage by particles flow in the plug in function of velocity in the linear model of Civan, construct and determine the model for estimate the profiles of damages in function of the radius, validate the scheme with field data for estimate the impact of damage and the critical radius of the producing well. At the present time more than 50% of the oil fields operate by Ecopetrol display formation damage by particle process, the quantity of the petroleum that it stop producing by this phenomenon is estimated in the thousands of barrels, with this kind of approximation it’s can be design and optimize the treatment require for mitigate the damage and recover a significate percentage of the barrels left out of production. In this project it’s show the entire process using data from the formation Barco of Cupiagua field, the scaling results indicate drops of permeability of 65% by this type of amage, damage radius between 1.9 and 4.4 ft and skin value by fines between 1.9 and 3.4. This process allows to generate the designs of the stimulating treatment for this field

Spontaneous magnetization of aluminum nanowires deposited on the NaCl(100) surface

We investigate electronic structures of Al quantum wires, both unsupported and supported on the (100) NaCl surface, using the density-functional theory. We confirm that unsupported nanowires, constrained to be linear, show magnetization when elongated beyond the equilibrium length. Allowing ions to relax, the wires deform to zig-zag structures with lower magnetization but no dimerization occurs. When an Al wire is deposited on the NaCl surface, a zig-zag geometry emerges again. The magnetization changes moderately from that for the corresponding unsupported wire. We analyse the findings using electron band structures and simple model wires.Comment: submitted to PHys. Rev.

Spontaneous Magnetization and Electron Momentum Density in 3D Quantum Dots

We discuss an exactly solvable model Hamiltonian for describing the interacting electron gas in a quantum dot. Results for a spherical square well confining potential are presented. The ground state is found to exhibit striking oscillations in spin polarization with dot radius at a fixed electron density. These oscillations are shown to induce characteristic signatures in the momentum density of the electron gas, providing a novel route for direct experimental observation of the dot magnetization via spectroscopies sensitive to the electron momentum density.Comment: 5 pages (Revtex4), 4 (eps) figure

Magnetic phenomena in 5d transition metal nanowires

We have carried out fully relativistic full-potential, spin-polarized, all-electron density-functional calculations for straight, monatomic nanowires of the 5d transition and noble metals Os, Ir, Pt and Au. We find that, of these metal nanowires, Os and Pt have mean-field magnetic moments for values of the bond length at equilibrium. In the case of Au and Ir, the wires need to be slightly stretched in order to spin polarize. An analysis of the band structures of the wires indicate that the superparamagnetic state that our calculations suggest will affect the conductance through the wires -- though not by a large amount -- at least in the absence of magnetic domain walls. It should thus lead to a characteristic temperature- and field dependent conductance, and may also cause a significant spin polarization of the transmitted current.Comment: 7 pages, 5 figure

First-Principles Study on Peierls Instability in Infinite Single-Row Al Wires

We present the relation between the atomic and spin-electronic structures of infinite single-row atomic wires made of Al atoms during their elongation using first-principles molecular-dynamics simulations. Our study reveals that the Peierls transition indeed occurs in the wire with magnetic ordering: it ruptures to form a trimerized structure with antiferromagnetic ordering and changes from a conductor to an insulator just before forming a linear wire of equally-spaced atoms. The formation of the trimerized wire is discussed in terms of the behavior of the $\sigma$-symmetry bands of the Al wire.Comment: 10 pages, 4 figure