University of Los Andes

About: University of Los Andes is a education organization based out in Bogotá, Colombia. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 17616 authors who have published 25555 publications receiving 413463 citations.

The Ciclovía-Recreativa: A Mass-Recreational Program With Public Health Potential

Abstract: Background: The Ciclovia-Recreativa is a free, community-based program in which streets are closed temporarily to motorized transport, allowing access to walkers, runners, rollerbladers, and cyclists only. We assessed existing information about the Ciclovia as a public health strategy and proposed next steps for research and public health practice. Methods: We conducted a systematic search of peer-reviewed and other literature, which was complemented by expert interviews and consultation. Results: We reviewed 38 Ciclovias from 11 countries. Most programs (84.2%) take place in urban settings. The programs range from 18–64 events per year (54 ± 24.6; 52 [mean ± standard deviation; median]) with events lasting from 2–12 hours (6 ± 2.4; 6). The length of the streets ranges from 1–121 km (14.6 ± 22.1; 7), and the estimated number of participants per event ranges from 60-1,000,000 persons (61,203 ± 186,668; 3810). Seventy-one percent of the programs include physical activity classes and in 89% of the Ciclovias, the streets are connected with parks. Conclusions: Ciclovias have potential for positive public health outcomes, but evidence on their effectiveness is limited. The different stages of new and established programs offer a unique opportunity for transnational studies aimed at assessing their public health impact.

Breaking of Water-in-Crude Oil Emulsions. 1. Physicochemical Phenomenology of Demulsifier Action

Abstract: Water-in-oil emulsions formed during oil slicks or petroleum production are known to be stabilized by surfactant molecules that naturally occur in the crude oil, e.g., asphaltenes, which are quite lipophilic in nature. Demulsifier substances combine with naturally occurring surfactants to attain a so-called optimum formulation at which the stability of the emulsion is minimum. The attainment of this formulation is related to the hydrophilicity and concentration of the added demulsifier, and a general phenomenology of the demulsification process is outlined.

Effects of Rote, Context, Keyword, and Context/Keyword Methods on Retention of Vocabulary in EFL Classrooms

Abstract: In the present study, the effects of rote rehearsal, context, keyword, andcontext/keyword methods on immediate and long-term retention of English as a foreign language(EFL) vocabulary in natural classroom settings was examined. 8 intact 9th-grade EFL classes were randomly assigned to 1 of 4 learning conditions: rote rehearsal, context, keyword, and context/keyword condition. Cued recall was assessed either immediately or after a 1-week delay. Results showed that the context/keyword method produced superior recall to any of the other 3 methods after 1 week, suggesting a very promising educational value for this method.

Spatial structures and localization of vacuum entanglement in the linear harmonic chain

Abstract: We study the structure of vacuum entanglement for two complimentary segments of a linear harmonic chain, applying the modewise decomposition of entangled Gaussian states discussed by Boteno and Reznik [Phys. Rev. A 67, 052311 (2003)]. We find that the resulting entangled mode-shape hierarchy shows a distinctive layered structure with well-defined relations between the depth of the modes, their characteristic wavelength, and their entanglement contribution. We rederive in the strong coupling (diverging correlation length) regime, the logarithmic dependence of entanglement on the segment size predicted by conformal field theory for the boson universality class and discuss its relation with the mode structure. We conjecture that the persistence of vacuum entanglement between arbitrarily separated finite-size regions is connected with the localization of the highest-frequency innermost modes.

Variability in earthquake stress drop and apparent stress

Abstract: [1] We apply empirical Green's function coda-based analysis to four earthquake sequences in Japan that span a magnitude range of 1.8 to 6.9, to measure radiated energy, corner frequency and stress drop. We find no systematic dependence of apparent stress or stress drop on seismic moment for these sequences, and find they both are log-normally distributed; however, we identify several anomalous events - both energetic and enervated - that show sharply different spectral signatures from the rest of the population. These events indicate that much of the variation in apparent stress and stress drop is statistically significant, which may have important implications for seismic hazard analysis.