Observer dependent entanglement

Understanding the observer-dependent nature of quantum entanglement has been a central question in relativistic quantum information. In this paper we will review key results on relativistic entanglement in flat and curved spacetime and discuss recent work which shows that motion and gravity have observable effects on entanglement between localized systems.Comment: Ivette Fuentes previously published as Ivette Fuentes-Guridi and Ivette Fuentes-Schulle

Skill-biased Technology Adoption: Evidence for the Chilean manufacturing sector

We examine the evolution of the demand for skilled workers relative to unskilled workers in the Chilean manufacturing sector following Chile’s liberalization of trade in the late 1970’s. Following such trade reforms, the standard Heckscher-Olin model predicts that a low labor-cost country like Chile should experience an increased demand for low skilled workers relative to high skilled workers. Alternatively, if trade liberalization is associated with the adoption of new technologies, and technology is skill-biased, the relative demand for skilled workers may rise. Using a newly available plant-level data set that spans the sixteen year period 1979-1995, we find that the relative demand for skilled workers rose sharply during the 1979-1986 period and then stabilized. The sharp increase in demand for skilled workers coincided with an increased propensity to adopt new technologies as measured by patent usage. Plant-level analysis of labor demand confirms a significant relationship between the relative demand for skilled workers and technology adoption as measured by patent usage and other technology indicators. Our results suggest that skill-biased technological change is a significant determinant of labor demand and wage structures in developing economies.

A simple model for the evolution of multi-stranded coronal loops

We develop and analyze a simple cellular automaton (CA) model that reproduces the main properties of the evolution of soft X-ray coronal loops. We are motivated by the observation that these loops evolve in three distinguishable phases that suggest the development, maintainance, and decay of a self-organized system. The model is based on the idea that loops are made of elemental strands that are heated by the relaxation of magnetic stress in the form of nanoflares. In this vision, usually called "the Parker conjecture" (Parker 1988), the origin of stress is the displacement of the strand footpoints due to photospheric convective motions. Modeling the response and evolution of the plasma we obtain synthetic light curves that have the same characteristic properties (intensity, fluctuations, and timescales) as the observed cases. We study the dependence of these properties on the model parameters and find scaling laws that can be used as observational predictions of the model. We discuss the implications of our results for the interpretation of recent loop observations in different wavelengths.Comment: 2010, accepted for publication in Ap

Are constant loop widths an artifact of the background and the spatial resolution?

We study the effect of the coronal background in the determination of the diameter of EUV loops, and we analyze the suitability of the procedure followed in a previous paper (L\'opez Fuentes, Klimchuk & D\'emoulin 2006) for characterizing their expansion properties. For the analysis we create different synthetic loops and we place them on real backgrounds from data obtained with the Transition Region and Coronal Explorer (\textit{TRACE}). We apply to these loops the same procedure followed in our previous works, and we compare the results with real loop observations. We demonstrate that the procedure allows us to distinguish constant width loops from loops that expand appreciably with height, as predicted by simple force-free field models. This holds even for loops near the resolution limit. The procedure can easily determine when loops are below resolution limit and therefore not reliably measured. We find that small-scale variations in the measured loop width are likely due to imperfections in the background subtraction. The greatest errors occur in especially narrow loops and in places where the background is especially bright relative to the loop. We stress, however, that these effects do not impact the ability to measure large-scale variations. The result that observed loops do not expand systematically with height is robust.Comment: Accepted for publication in Ap