EL PROCESO DE ENSEÑANZA-APRENDIZAJE Y SU ENFOQUE SISTÉMICO EN LA UNIVERSIDAD DE GUAYAQUIL, ECUADOR

El artículo es un análisis sobre la pertinencia y necesidad de concebir el proceso de enseñanza-aprendizaje de la Educación Superior con un enfoque sistémico, revelando los nexos entre los componentes académico, investigativo y de vinculación con la sociedad. Se argumenta la relación de este proceso con la superación posgraduada de los docentes y la investigación científica en las instituciones de la Educación Superior

El factor de crecimiento epidérmico induce transición epitelio-mesénquima en cultivos primarios de cáncer de mama

ResumenAntecedentesLa transición epitelio-mesénquima (TEM) es un proceso biológico en el que células epiteliales inmóviles y polarizadas se convierten en células mesenquimales con capacidad de migración. Este proceso produce cambios en el citoesqueleto de las células, siendo la pérdida de E-cadherina y la adquisición de N-cadherina, uno de los principales cambios bioquímicos que se dan en la TEM. En este estudio investigamos el papel del factor de crecimiento epidérmico (EGF) sobre la TEM inducida en líneas celulares y cultivos primarios de cáncer de mama.MétodosPara este estudio se empleó la línea celular de cáncer de mama MCF-7 y los cultivos primarios MBCD25 y MBCDF. Se indujo la TEM mediante el tratamiento continuo con EGF. Se evaluó si las células habían sido inducidas a un fenotipo mesenquimatoso con EGF mediante la técnica de western blot, midiendo la fosforilación de STAT3, el nivel de STAT3, y la represión de los marcadores como E-cadherina, así como la expresión del factor de transcripción Snail.ResultadosNuestros resultados demuestran que el tratamiento con EGF induce la fosforilación de STAT3 sin cambios en sus niveles totales en células MBCDF, MBCD25 y MCF-7. Asimismo, el tratamiento con EGF por 5 días induce una TEM, que se demostró por la pérdida de E-cadherina y la expresión de Snail.ConclusiónEn los cultivos primarios MBCD25 y MBCDF, así como en la línea celular MCF-7, el EGF es capaz de inducir TEM y en consecuencia producir un fenotipo más agresivo de las células de cáncer de mama.AbstractBackgroundEpithelial-mesenchymal transition (EMT) is a biological process where immobile and polarised epithelial cells acquire mesenchymal characteristics with high migration. This process produces changes in the cytoskeleton of the tumour cells, with the loss of E-cadherin and the acquisition of N-cadherin being the main biochemical changes of the EMT. This study investigates the role of epidermal growth factor (EGF) on the EMT induction in breast cancer cell lines and primary cultures.MethodsMCF-7 cell line and the primary cultures MBCDF and MBCD25 were used in this study. EMT was induced by continuous EGF treatment. Mesenchymal EGF-induced phenotype was evaluated by Western blot of the following markers: pSTAT3, STAT3, repression of E-cadherin, and expression of Snail.ResultsOur results demonstrate that EGF treatment induced STAT3 phosphorylation without changes in STAT3 in MBCDF, MBCD25 and MCF-7. Additionally, EGF treatment induced EMT, as shown by the loss of E-cadherin and Snail expression after 5 days.ConclusionEGF was able to induce EMT in primary breast cancer cell cultures, MBCDF, MBCD25, as well as MCF-7 cell line. These results suggest that EGF produces a putative aggressive phenotype

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Search for Physics beyond the Standard Model in Events with Overlapping Photons and Jets

Results are reported from a search for new particles that decay into a photon and two gluons, in events with jets. Novel jet substructure techniques are developed that allow photons to be identified in an environment densely populated with hadrons. The analyzed proton-proton collision data were collected by the CMS experiment at the LHC, in 2016 at root s = 13 TeV, and correspond to an integrated luminosity of 35.9 fb(-1). The spectra of total transverse hadronic energy of candidate events are examined for deviations from the standard model predictions. No statistically significant excess is observed over the expected background. The first cross section limits on new physics processes resulting in such events are set. The results are interpreted as upper limits on the rate of gluino pair production, utilizing a simplified stealth supersymmetry model. The excluded gluino masses extend up to 1.7 TeV, for a neutralino mass of 200 GeV and exceed previous mass constraints set by analyses targeting events with isolated photons.Peer reviewe

Calibration of the CMS hadron calorimeters using proton-proton collision data at root s=13 TeV

Methods are presented for calibrating the hadron calorimeter system of theCMSetector at the LHC. The hadron calorimeters of the CMS experiment are sampling calorimeters of brass and scintillator, and are in the form of one central detector and two endcaps. These calorimeters cover pseudorapidities vertical bar eta vertical bar ee data. The energy scale of the outer calorimeters has been determined with test beam data and is confirmed through data with high transverse momentum jets. In this paper, we present the details of the calibration methods and accuracy.Peer reviewe

Measurement of the Jet Mass Distribution and Top Quark Mass in Hadronic Decays of Boosted Top Quarks in pp Collisions at root s=13 TeV

A measurement is reported of the jet mass distribution in hadronic decays of boosted top quarks produced in pp collisions at root s = 13 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lepton + jets channel of t (t) over bar events, where the lepton is an electron or muon. The products of the hadronic top quark decay t -> bW -> bq (q) over bar' are reconstructed as a single jet with transverse momentum larger than 400 GeV. The t (t) over bar cross section as a function of the jet mass is unfolded at the particle level and used to extract a value of the top quark mass of 172.6 +/- 2.5 GeV. A novel jet reconstruction technique is used for the first time at the LHC, which improves the precision by a factor of 3 relative to an earlier measurement. This highlights the potential of measurements using boosted top quarks, where the new technique will enable future precision measurements.Peer reviewe

Search for top squark pair production in a final state with two tau leptons in proton-proton collisions at root s=13 TeV

A search for pair production of the supersymmetric partner of the top quark, the top squark, in proton-proton collision events at s = 13 TeV is presented in a final state containing hadronically decaying tau leptons and large missing transverse momentum. This final state is highly sensitive to high-tan beta or higgsino-like scenarios in which decays of electroweak gauginos to tau leptons are dominant. The search uses a data set corresponding to an integrated luminosity of 77.2 fb(-1), which was recorded with the CMS detector during 2016 and 2017. No significant excess is observed with respect to the background prediction. Exclusion limits at 95% confidence level are presented in the top squark and lightest neutralino mass plane within the framework of simplified models, in which top squark masses up to 1100 GeV are excluded for a nearly massless neutralino.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe

Search for charged Higgs bosons decaying into a top and a bottom quark in the all-jet final state of pp collisions at root s=13 TeV

A search for charged Higgs bosons (H-+/-) decaying into a top and a bottom quark in the all-jet final state is presented. The analysis uses LHC proton-proton collision data recorded with the CMS detector in 2016 at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). No significant excess is observed above the expected background. Model-independent upper limits at 95% confidence level are set on the product of the H-+/- production cross section and branching fraction in two scenarios. For production in association with a top quark, limits of 21.3 to 0.007 pb are obtained for H-+/- masses in the range of 0.2 to 3 TeV. Combining this with a search in leptonic final states results in improved limits of 9.25 to 0.005 pb. The complementary s-channel production of an H-+/- is investigated in the mass range of 0.8 to 3 TeV and the corresponding upper limits are 4.5 to 0.023 pb. These results are interpreted using different minimal supersymmetric extensions of the standard model.Peer reviewe