Socialism is the only answer

https://stars.library.ucf.edu/prism/1531/thumbnail.jp

The ABC of socialism

https://stars.library.ucf.edu/prism/1068/thumbnail.jp

Dissipative Chaos in Semiconductor Superlattices

We consider the motion of ballistic electrons in a miniband of a semiconductor superlattice (SSL) under the influence of an external, time-periodic electric field. We use the semi-classical balance-equation approach which incorporates elastic and inelastic scattering (as dissipation) and the self-consistent field generated by the electron motion. The coupling of electrons in the miniband to the self-consistent field produces a cooperative nonlinear oscillatory mode which, when interacting with the oscillatory external field and the intrinsic Bloch-type oscillatory mode, can lead to complicated dynamics, including dissipative chaos. For a range of values of the dissipation parameters we determine the regions in the amplitude-frequency plane of the external field in which chaos can occur. Our results suggest that for terahertz external fields of the amplitudes achieved by present-day free electron lasers, chaos may be observable in SSLs. We clarify the nature of this novel nonlinear dynamics in the superlattice-external field system by exploring analogies to the Dicke model of an ensemble of two-level atoms coupled with a resonant cavity field and to Josephson junctions.Comment: 33 pages, 8 figure

Pulmonary Function and Incident Bronchitis and Asthma in Children: A Community-Based Prospective Cohort Study

BACKGROUND: Previous studies revealed that reduction of airway caliber in infancy might increase the risks for wheezing and asthma. However, the evidence for the predictive effects of pulmonary function on respiratory health in children was still inconsistent. METHODS: We conducted a population-based prospective cohort study among children in 14 Taiwanese communities. There were 3,160 children completed pulmonary function tests in 2007 and follow-up questionnaire in 2009. Poisson regression models were performed to estimate the effect of pulmonary function on the development of bronchitis and asthma. RESULTS: After adjustment for potential confounders, pulmonary function indices consistently showed protective effects on respiratory diseases in children. The incidence rate ratios of bronchitis and asthma were 0.86 (95% CI 0.79-0.95) and 0.91 (95% CI 0.82-0.99) for forced expiratory volume in 1 second (FEV₁). Similar adverse effects of maximal mid-expiratory flow (MMEF) were also observed on bronchitis (RR = 0.73, 95% CI 0.67-0.81) and asthma (RR = 0.85, 95% CI 0.77-0.93). We found significant decreasing trends in categorized FEV₁ (p for trend = 0.02) and categories of MMEF (p for trend = 0.01) for incident bronchitis. Significant modification effects of traffic-related air pollution were noted for FEV₁ and MMEF on bronchitis and also for MMEF on asthma. CONCLUSIONS: Children with high pulmonary function would have lower risks on the development of bronchitis and asthma. The protective effect of high pulmonary function would be modified by traffic-related air pollution exposure

El Socialismo en Cuba

El socialismo en Cuba es un estudio obviamente controvertible, que intenta examinar una realidad compleja y extraordinariamente fluida, frente a la cual, es muy difícil no incurrir en errores de apreciación. En años pasados podía haber sido relativamente fácil referirse dogmáticamente a una situación como la que ahora vive Cuba, partiendo de ciertos esquemas que algunos empleaban aunque para ello fuese preciso despojar al marxismo de su fuerza creadora. Pero después de que la propia Revolución Cubana ha roto con esos y con tantos otros esquemas resulta imposible hacerlo. Aún hoy no sería difícil escribir una mediana o hasta una buena monografía limitándose a ordenar ciertos hechos y a destacar las principales tendencias del proceso cubano, sin intentar siquiera el examen de problemas de fondo. Quienes conocen a Huberman y Sweezy, que a lo largo de más de dos décadas han dicho sin reservas lo que piensan sobre las cuestiones políticas más graves, comprenderán que para ellos habría carecido de sentido viajar a Cuba, recorrer el país, hablar con decenas de personas, estudiar materiales de primera mano y, después de todo ello, limitarse a hacer una crónica superficial y meramente apologética de hechos bien conocidos. Editorial Nuestro Tiempo confía en que la publicación de este libro será útil, y en que ayudará a comprender mejor y más objetivamente el proceso revolucionario cubano, e incluso, a ganar nuevos amigos para la Revolución. Acaso no falten quienes, por no compartir algunas opiniones de los autores, nos critiquen por haberlo editado. Mas en un momento como éste, en el que aún en el seno del movimiento socialista internacional existen diferencias, los desacuerdos, las tensiones y los graves conflictos que todos conocemos y lamentamos, parecería a todas luces desmedido y pedante asumir el papel de jueces y adoptar una actitud cerrada y dogmática frente a problemas de la lucha revolucionaria, que acabaría por reducirnos al silencio, que a menudo nos obligaría a tomar posturas pontificales y que, en última instancia, solo conduciría a liquidar el modesto esfuerzo editorial en que estamos empeñados

Dynamics of spontaneous activity in the fetal macaque retina during development of retinogeniculate pathways

Correlated spontaneous activity in the form of retinal waves has been observed in a wide variety of developing animals, but whether retinal waves occur in the primate has not been determined previously. To address this issue, we recorded from isolated retinas using multielectrode arrays at six fetal ages: embryonic day 51 (E51), E55, E60, E67, E71, and E76. These recordings revealed that the fetal monkey retina is essentially silent at E51 and E55, with only few cells firing on rare occasions and without any obvious spatial or temporal order. Because previous work has shown that the magnocellular and parvocellular subdivisions of the dorsal lateral geniculate are selectively innervated during this early period, our results suggest that this process is unlikely to be regulated by retinal activity. Highly structured retinal waves were first observed at E60, \u3e1 week before the segregation of eye-specific retinal dorsal lateral geniculate nucleus projections commences. The incidence of such waves decreased rapidly and progressively during the developmental period (E67-E76) when segregated eye-specific projections become established. Our findings indicate that retinal waves first occur in the fetal monkey at a remarkably early stage of development, \u3e100 d before birth, and that this activity undergoes rapid changes in salient properties when eye-specific retinogeniculate projections are being formed. Copyright © 2006 Society for Neuroscience

Early and rapid targeting of eye-specific axonal projections to the dorsal lateral geniculate nucleus in the fetal macaque

The emergence of eye-specific axonal projections to the dorsal lateral geniculate nucleus (dLGN) is a well established model system for exploring the mechanisms underlying afferent targeting during development. Using modern tract tracing methods, we examined the development of this feature in the macaque, an Old World Primate with a visual system similar to that of humans. Cholera toxin β fragment conjugated to Alexa 488 was injected into the vitreous of one eye, and CTβ conjugated to Alexa 594 into the other eye of embryos at known gestational ages. On embryonic day 69 (E69), which is ∼100 d before birth, inputs from the two eyes were extensively intermingled in the dLGN. However, even at this early age, portions of the dLGN were preferentially innervated by the right or left eye, and segregation is complete within the dorsalmost layers 5 and 6. By E78, eye-specific segregation is clearly established throughout the parvocellular division of the dLGN, and substantial ocular segregation is present in the magnocellular division. By E84, segregation of left and right eye axons is essentially complete, and the six eye-specific domains that characterize the mature macaque dLGN are clearly discernable. These findings reveal that targeting of eye-specific axonal projections in the macaque occurs much earlier and more rapidly than previously reported. This segregation process is completed before the reported onset of ganglion cell axon loss and retino-dLGN synapse elimination, suggesting that, in the primate, eye-specific targeting occurs independent of traditional forms of synaptic plasticity. Copyright © 2005 Society for Neuroscience