Tipos de aprendizaje y tendencia según modelo VAK

En las aulas de clase se evidencia a menudo que los docentes tienen dificultades para transmitir sus conocimientos hacia los estudiantes. Esto sucede por múltiples factores, entre ellos, se encuentra la forma en cómo cada persona logra captar la información para poder retroalimentar su conocimiento. En éste artículo se muestra una tendencia presentada según cifras de estudio de la Universidad Internacional SEK de Chile, en cuanto al análisis de tipos de aprendizaje para algunas áreas de ésta universidad. Ya que la naturaleza humana es una sola, podrían tomarse dichas cifras como un referente general hacia dónde deben ir encaminadas las metodologías usadas por los educadores para impartir su conocimiento en las aulas de clase

Empleo de suspensiones celulares embriogénicas y radiaciones Gamma fuente 60Co en la mutagénesis in vitro de banano cv. ‘Manzano’ (Musa AAB)

The in vitro induction of mutations combined with somatic embryogenesis increases the efficiency of mutagenic treatments. This work was carried out with the aim of determining the effect of 60Co source Gamma radiation on embryogenic cell suspensions of banana cv. 'Manzano' (Musa AAB). Different doses of radiation (30, 40, 50, 60, 70 and 80 Gy) were applied to embryogenic cell suspensions in the multiplying phase and subsequently subcultured to culture media for the formation, maturation and germination of somatic embryos. A non-irradiated control was used. Subsequently, the regenerated plants were transferred to the greenhouse for their acclimatization. At 45 days, survival and phenotypic variations were evaluated. According to the weighted mean of the variables included, it was possible to select 40 Gy as the most effective dose (GR50 and LD50), based on the variables number of germinated somatic embryos and survival percentage. The results of this study allow us to know the range of radiosensitivity for the application of Gamma radiation from a 60Co source that can induce improved characters of agronomic interest in banana cv. 'Manzano' to be used in genetic improvement programs. La inducción de mutaciones in vitro combinada con la embriogénesis somática aumenta la eficiencia de los tratamientos mutagénicos. Este trabajo se realizó con el objetivo de determinar el efecto de las radiaciones Gamma fuente 60Co en suspensiones celulares embriogénicas de banano cv. ‘Manzano’ (Musa AAB). Se aplicaron diferentes dosis de radiación (30, 40, 50, 60, 70 y 80 Gy) a suspensiones celulares embriogénicas en fase de multiplicación y posteriormente se subcultivaron a medios de cultivo para la formación, maduración y germinación de los embriones somáticos. Se empleó un control sin irradiar. Posteriormente, se trasladaron las plantas regeneradas a casa de cultivo para su aclimatización. A los 45 días se evaluó la supervivencia y las variaciones fenotípicas. De acuerdo con la media ponderada de las variables incluidas se logró seleccionar 40 Gy como la dosis más efectiva (GR50 y la DL50), a partir de las variables número de embriones somáticos germinados y porcentaje de supervivencia. Los resultados de este estudio permiten conocer el rango de radiosensibilidad para la aplicación de radiaciones Gamma fuente 60Co que pueda inducir caracteres mejorados de interés agronómico en banano cv. ‘Manzano’ para ser empleados en programas de mejora genética

Use of embryogenic cell suspensions and 60Co source gamma radiationduring in vitro mutagenesis in banana cv. ‘Manzano’ (Musa AAB)

The in vitro induction of mutations combined with somatic embryogenesis increases the efficiency of mutagenic treatments. This work was carried out with the aim of determining the effect of 60Co source Gamma radiation on embryogenic cell suspensions of banana cv. ‘Manzano’ (MusaAAB). Different doses of radiation (30, 40, 50, 60, 70 and 80 Gy) were applied to embryogeniccell suspensions in the multiplying phase and subsequently subcultured to culture media forthe formation, maturation and germination of somatic embryos. A non-irradiated control wasused. Subsequently, the regenerated plants were transferred to the greenhouse for their acclimatization. At 45 days, survival and phenotypic variations were evaluated. According tothe weighted mean of the variables included, it was possible to select 40 Gy as the mosteffe ctive dose (GR50 and LD50), base d on the variable s numbe r of ge rminated somatic embryosand survival percentage. The results of this study allow us to know the range of radiosensitivity for the application of Gamma radiation from a 60Co source that can induce improved characters of agronomic interest in banana cv. ‘Manzano’ to be used in genetic improvement programs

Mutagénesis in vitro en suspensiones celulares embriogénicas de banano cv. Grande naine (Musa AAA)

Somatic embryogenesis is a useful process for clonal propagation and genetic improvement by induction of mutations. This work was carried out with the objective of determining the effect of 60Co source Gamma radiations on embryogenic cell suspensions of banana cv. 'Grande naine' (Musa AAA) until conversion to plants. Different doses of radiation (0, 30, 40, 50, 60, 70 and 80 Gy) were applied to embryogenic cell suspensions in the multiplication phase and the embryos were later formed, matured and germinated. To determine the ex vitro response of the population of plants obtained these were transferred to greenhouse. The results showed that with somatic embryos formed fresh mass no differences were observed between the effect of the different doses of radiation applied and the control. However, the radiation dose affected the percentage of somatic embryo formation and germination. Plants with phenotypic variations were regenerated with 40 Gy. The results at the greenhouse showed that as radiation doses increased up to 50 Gy, the frequency of variations increased. With higher doses of radiation the survival of the plants was affected. Keywords: Gamma radiation, in vitro mutagenesis, radiation dose, radiosensibility, somatic embryoLa embriogénesis somática es un proceso útil para la propagación clonal y el mejoramiento genético por inducción de mutaciones. Este trabajo se realizó con el objetivo de determinar el efecto de radiaciones Gamma fuente 60Co en suspensiones celulares embriogénicas de banano cv. ‘Grande naine’ (Musa AAA) hasta la conversión en plantas. Se aplicaron diferentes dosis de radiación (0, 30, 40, 50, 60, 70 y 80 Gy) a suspensiones celulares embriogénicas en fase de multiplicación y posteriormente se pusieron a formar, madurar y germinar los embriones. Para determinar la respuesta ex vitro de la población de plantas obtenidas estas se transfirieron a casa de cultivo.Los resultados mostraron que con el indicador masa fresca de los embriones somáticos formados no se observaron diferencias entre el efecto de las diferentes dosis de radiación aplicadas y el control. Sin embargo, la dosis de radiación afectó el porcentaje de formación y germinación de embriones somáticos. Con el empleo de 40 Gy se regeneraron plantas con variaciones fenotípicas. Los resultados en casa de cultivo evidenciaron que a medida que aumentaron las dosis de radiación hasta 50 Gy se incrementó la frecuencia de variaciones. Con dosis de radiación superiores se afectó la supervivencia de las plantas. Palabras clave: dosis de radiación, embrión somático, radiaciones Gamma, radiosensibilida

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

X-ray emission from the Sombrero galaxy: discrete sources

We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO