Coeficiente intelectual y factores asociados en niños escolarizados en la ciudad de medellín, colombia

Objetivo Analizar el coeficiente intelectual y los factores asociados en niños escolarizados de 6 a 8 años en las comunas Nororiental y Norocidental de la ciudad de Medellín-Colombia. Materiales y Métodos Se realizó un muestreo aleatorio simple, polietápico y estratificado según grado escolar y comuna, la muestra estuvo constituida por 423 niños de ambos sexos. El coeficiente intelectual se evaluó con la Escala de Inteligencia Wechsler para Niños WISC-IV y la estimulación psicosocial con Observation for Measurement of the Environment (HOME). Para la valoración del estado nutricional se utilizó las normas de referencia y puntos de corte de la OMS.Resultados Los factores de riesgo que explican las puntuaciones en el Coeficiente Intelectual Total y sus índices fueron: historia de problemas académicos de la madre y padre e historia de problemas de comportamiento de los hermanos, alcoholismo de la madre durante el embarazo y conductas agresivas en el hogar. Conclusión En los niños que cursan los primeros años de escolaridad en las dos comunas más pobres de Medellín, el coeficiente intelectual y sus índices se encuentra correlacionado con factores de antecedencia psicosocial y conductas agresivas en el hogar

Propiedades mecánicas del acero de refuerzo utilizado en Colombia

Results of the statistical analysis applied to the experimental study that determine the mechanical properties of Colombian steels subjected to monotonic tensile loads are presented. Typical stress-strain curves are obtained that allow characterizing national steels studied by emphasizing the variables that determine the change in material behaviorSe presentan resultados del análisis estadístico aplicado al estudio experimental que de- termina las propiedades mecánicas de aceros colombianos sometidos a cargas monotónicas de tracción. Se obtienen curvas típicas de esfuerzo-deformación que permiten caracterizar aceros nacionales estudiados haciendo énfasis en las variables que determinan el cambio de comportamiento del materia

Propiedades mecánicas del acero de refuerzo utilizado en Colombia

A statistical analysis applied to a experimental study that determines the mechanical properties of steels produced in Colombia subjected to monotonic loads of tension is presented. Typical stress-strain diagram that allow to characterize these steels making emphasis in the variables that determine the change of behaviour of the materia are presented.PACS: 62.20.-xSe presentan resultados del análisis estadístico aplicado al estudio experimental que de- termina las propiedades mecánicas de aceros colombianos sometidos a cargas monotónicas de tracción. Se obtienen curvas típicas de esfuerzo-deformación que permiten caracterizar aceros nacionales estudiados haciendo énfasis en las variables que determinan el cambio de comportamiento del materialPACS: 62.20.-

Características psicométricas de la escala de seguridad alimentaria ELCSA aplicada en Colombia, Guatemala y México.

La inseguridad alimentaria es un fenómeno que afecta a millones de hogares en América Latina. Herramientas válidas y confiables para su medición son esenciales para la mejor focalización de los programas abocados a este problema. La Escala Latinoamericana y del Caribe de Seguridad Alimentaria (ELCSA) ha sido propuesta como instrumento regional y fue recientemente aplicada en Colombia, Guatemala y México. Este estudio evalúa las características psicométricas del instrumento y estima el grado de similitude entre esas mediciones. Inicialmente, se determinó que 15 ítems tuvieron contenidos equivalentes en los tres países. Al aplicarle el modelo matemático de Rasch, ELCSA mostró buen ajuste a ese modelo y un comportamiento consistente con el marco conceptual subyacente. Sin embargo, entre Guatemala y México se detectaron diferencias mayores a 1,0 lógitos en cuatro ítems, de los cuales uno solo presentó una diferencia cercana a 2 lógitos. Al omitir este ítem de subsiguientes análisis se atenuaron las diferencias en los otros ítems. Variaciones en el lenguaje, así como en el diseño de las muestras analizadas explicarían en parte los resultados de este estudio. A pesar de las diferencias detectadas, ELCSA parece medir de manera similar la experiencia de los hogares que confrontan situaciones de inseguridad alimentaria

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe

Observation of tW production in the single-lepton channel in pp collisions at root s=13 TeV

A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at root s = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb(-1) collected with the CMS detector at the CERN LHC in 2016. A boosted decision tree is used to separate the tW signal from the dominant t (t) over bar background, whilst the subleading W+jets and multijet backgrounds are constrained using data-based estimates. This result is the first observation of the tW process in final states containing a muon or electron and jets, with a significance exceeding 5 standard deviations. The cross section is determined to be 89 +/- 4 (stat) +/- 12 (syst) pb, consistent with the standard model.Peer reviewe

Measurements of the Electroweak Diboson Production Cross Sections in Proton-Proton Collisions at root s=5.02 TeV Using Leptonic Decays

The first measurements of diboson production cross sections in proton-proton interactions at a center-of-mass energy of 5.02 TeV are reported. They are based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 302 pb(-1). Events with two, three, or four charged light leptons (electrons or muons) in the final state are analyzed. The WW, WZ, and ZZ total cross sections are measured as sigma(WW) = 37:0(-5.2)(+5.5) (stat)(-2.6)(+2.7) (syst) pb, sigma(WZ) = 6.4(-2.1)(+2.5) (stat)(-0.3)(+0.5)(syst) pb, and sigma(ZZ) = 5.3(-2.1)(+2.5)(stat)(-0.4)(+0.5) (syst) pb. All measurements are in good agreement with theoretical calculations at combined next-to-next-to-leading order quantum chromodynamics and next-to-leading order electroweak accuracy

Search for lepton-flavor violating decays of the Higgs boson in the mu tau and e tau final states in proton-proton collisions at root s=13 TeV

A search is presented for lepton-flavor violating decays of the Higgs boson to mu t and et. The dataset corresponds to an integrated luminosity of 137 fb(-1) collected at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. No significant excess has been found, and the results are interpreted in terms of upper limits on lepton-flavor violating branching fractions of the Higgs boson. The observed (expected) upper limits on the branching fractions are, respectively, B(H -> mu t) e tau) < 0.22(0.16)% at 95% confidence level.Peer reviewe