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.

Consequences of shoaling of the Central American Seaway determined from modeling Nd isotopes

Abstract: The Central American Seaway played a pivotal role in shaping global climate throughout the late Cenozoic. Recent geological surveys have provided new constraints on timing of the seaway shoaling, while neodymium isotopic (e Nd) data measured on fossil teeth, debris, and ferromanganese crusts have helped define the history of water masses in the region. Here we provide the first 3-D simulations of e Nd responses to the shoaling seaway. Our model suggests that a narrow and shallow seaway is sufficient to affect interoceanic circulation, that inflow/ outflow balance between the Caribbean and the Antilles responds nonlinearly to sill depth, and that a seaway narrower than 400 km is consistent with an active Atlantic meridional overturning circulation during the late Miocene. Simulated e Nd values in the Caribbean confirm that inputs from radiogenic Pacific waters in the Caribbean decrease as the seaway shoals. Despite model limitations, a comparison between our results and e Nd values recorded in the Caribbean helps constrain the depth of the Central American Seaway through time, and we infer that a depth between 50 and 200 m could have been reached 10 Ma ago.

Search for neutral MSSM Higgs bosons decaying into a pair of bottom quarks

Abstract: A search for neutral Higgs bosons decaying into a b (b) over bar quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs sector of the minimal supersymmetric standard model (MSSM) with large values of the parameter tan beta. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 fb(-1). The results are combined with a previous analysis based on 7 TeV data. No signal is observed. Stringent upper limits on the cross section times branching fraction are derived for Higgs bosons with masses up to 900 GeV, and the results are interpreted within different MSSM benchmark scenarios, m(h)(max), m(h)(mod+), m(h)(mod-), light-stau and light-stop. Observed 95% confidence level upper limits on tan beta, ranging from 14 to 50, are obtained in the m(h)(mod+) benchmark scenario.

Effective constraints for quantum systems

Abstract: An effective formalism for quantum constrained systems is presented which allows manageable derivations of solutions and observables, including a treatment of physical reality conditions without requiring full knowledge of the physical inner product. Instead of a state equation from a constraint operator, an infinite system of constraint functions on the quantum phase space of expectation values and moments of states is used. The examples of linear constraints as well as the free non-relativistic particle in parametrized form illustrate how standard problems of constrained systems can be dealt with in this framework.

Quality of life, physical activity, and built environment characteristics among colombian adults.

Abstract: Background: Studies assessing the association between health-related quality of life (HR-QOL) with physical activity (PA) and built environment (BE) characteristics are limited. Methods: A cross-sectional study was conducted among 1,334 adults from Bogota, to assess the associations between HR-QOL with PA and BE characteristics. HR-QOL was measured using the World Health Organization and the Centers for Disease Control and Prevention instruments. PA was measured using the International PA Questionnaire. BE characteristics included the dimensions of density, diversity, design, and access to mass-transit. Analysis included multilevel modeling. Results: Adults who reported meeting PA recommendations and participating in the Ciclovia were more likely to have a high mean score of HR-QOL and were more likely to perceive their health status as good/excellent. Adults who reported biking for transportation were more likely to have a high mean score of HR-QOL. Regarding BE characteristics, land-use heterogeneity was associated with HR-QOL, perceived good health status and being positive about the future. Park density was associated with HR-QOL, perceived health status good/excellent and being positive about the future. Mass-transit stations availability was negatively associated with HR-QOL. Conclusion: This study provides preliminary evidence that HR-QOL is associated with PA and BE characteristics among adults in an urban setting of the developing world.