Alternative Approaches to Energy Modeling

The effects of government and private sector energy policies are varied and interrelated. Before implementing research and development programs, new technologies, environmental and price regulations, import quotas, and other energy-related policies, the consequences of these programs must be identified and quantified on a regional basis. To evaluate the regional impacts of energy policies, we need to consider production costs, transportation costs, and the location of reserves, as well as the demands for energy and nonenergy goods. Developing techniques for analyzing these factors was the objective of many previous research efforts. The strengths and weaknesses of the resulting models are discussed in this paper and areas for future research are outlined. Only those models that consider more than one fuel and sector (i.e., residential, utility, etc.) are reviewed

La Regla Taiji: el legado del Inmortal Durmiente

Este artículo describe la historia, desarrollo, y principios de los dos principales linajes del Taiji de la Regla: uno asociado con la familia imperial de la Dinastía Song (960-1279 d.C.), y el otro menos conocido, de linaje taoísta, trasmitido por Hu Yaozhen y sus sucesores, incluido el bien conocido maestro de taijiquan del estilo Chen, Feng Zhiqiang. El Taiji de la Regla es un sistema tradicional de qigong para aumentar la salud que se atribuye al ermitaño taoísta de la dinastía Song Chen Xiyi, y fue enseñado públicamente por primera vez en la década de los años 50. Los ejercicios pueden ser practicados mientras se sostiene un objeto de madera de un pie de largo, la Regla, o con una variedad de aparatos de entrenamiento, tales como una bola de madera o de piedra. El Sr. Cohen comenzó a estudiar el Taiji de la Regla con varios profesores hace más de 30 años, pero también basa su investigación en trabajos en chino e inglés. Tanto los profesores como la literatura están de acuerdo en que el objetivo final del Taiji de la Regla es armonizarse con el qi primitivo del universo y, en el proceso, obtener vitalidad y longevidad

Stretch Increases Alveolar Epithelial Permeability to Uncharged Micromolecules

We measured stretch-induced changes in transepithelial permeability in vitro to uncharged tracers 1.5–5.5 Å in radius to identify a critical stretch threshold associated with failure of the alveolar epithelial transport barrier. Cultured alveolar epithelial cells were subjected to a uniform cyclic (0.25 Hz) biaxial 12, 25, or 37% change in surface area (ΔSA) for 1 h. Additional cells served as unstretched controls. Only 37% ΔSA (100% total lung capacity) produced a significant increase in transepithelial tracer permeability, with the largest increases for bigger tracers. Using the permeability data, we modeled the epithelial permeability in each group as a population of small pores punctuated by occasional large pores. After 37% ΔSA, increases in paracellular transport were correlated with increases in the radii of both pore populations. Inhibition of protein kinase C and tyrosine kinase activity during stretch did not affect the permeability of stretched cells. In contrast, chelating intracellular calcium and/or stabilizing F-actin during 37% ΔSA stretch reduced but did not eliminate the stretch-induced increase in paracellular permeability. These results provide the first in vitro evidence that large magnitudes of stretch increase paracellular transport of micromolecules across the alveolar epithelium, partially mediated by intracellular signaling pathways. Our monolayer data are supported by whole lung permeability results, which also show an increase in alveolar permeability at high inflation volumes (20 ml/kg) at the same rate for both healthy and septic lungs