Multitemporal distribution analysis of Dodonaea viscosa (L.) Jacq. by remote sensing in Durango, Mexico

Objective: To determine the distribution of D. viscosa at the Guadalupe Victoria dam for the years 1990, 2010 and 2017. Design/methodology/approach: Landsat satellite images were processed in order to perform a supervised classification using an artificial neural network. The ground cover of pastures, crops, shrubs and oak forest was estimated from images for the years 1990, 2010 and 2017 at sites where the presence of D. viscosa had been recorded. These data were used to calculate the expansion of D. viscosa in the study area. Results: Limitations on study/implications: The supervised classification of the artificial neural network was optimal after 400 iterations, obtaining the best overall precision, 84.5%, for 2017. This contrasted with 1990, where overall precision was low, at 45%, because there were few training sites (fewer than 100) recorded for each of the land cover classes. Findings/conclusions: In 1990, D. viscosa was found on only five hectares, while by 2017 it had increased to 147 hectares. If the disturbance caused by overgrazing continues, the potential distribution projected for D. viscosa shows it invading half the study area, occupying agricultural, forested and scrub areas.Objective: to determine the distribution of D. viscosa in the vicinity of the Guadalupe Victoria Dam in Durango, Mexico, for the years 1990, 2010 and 2017.Design/Methodology/Approach: Landsat satellite images were processed in order to carry out supervised classifications using an artificial neural network. Images from the years 1990, 2010 and 2017 were used to estimate ground cover of D. viscosa, pastures, crops, shrubs, and oak forest. This data was used to calculate the expansion of D. viscosa in the study area.Results/Study Limitations/Implications: the supervised classification with the artificial neural network was optimal after 400 iterations, obtaining the best overall precision of 84.5 % for 2017. This contrasted with the year 1990, when overall accuracy was low at 45 % due to less training sites (fewer than 100) recorded for each of the land cover classes.Findings/Conclusions: in 1990, D. viscosa was found on only five hectares, while by 2017 it had increased to 147 hectares. If the disturbance caused by overgrazing continues, and based on the distribution of D. viscosa, it is likely that in a few years it will have the ability to invade half the study area, occupying agricultural, forested, and shrub area

Clima organizacional y engagement laboral en docentes de nivel secundaria en la región Junín

Objective. To establish the relationship between organizational climate and work engagement in secondary school teachers in the Junín region (Peru). Methods. The study had a quantitative approach, basic type for its purpose, correlational level and cross-sectional and correlational design. Two instruments were used: the organizational climate questionnaire which consisted of 23 items and whose dimensions were leadership, communication and motivation; and the work engagement questionnaire which consisted of 16 items and 3 dimensions: vigor, dedication and absorption. The sampling technique was non-probabilistic by convenience, and the sample consisted of 126 secondary school teachers. Results. 84.1 % perceived that the organizational climate was good and 69 % considered that work engagement was high. The hypothesis test confirms the significant relationship between both variables, since the p-value found was 0.001 and the Kendall's tau-b correlation strength was 0.363, which indicates that there is a medium-low correlation. Conclusion. There is sufficient evidence to affirm that the organizational climate has a lower level of incidence on work engagement, which, however, could be greater if educational institutions do not consider preventive measures.Objetivo. Establecer la relación entre clima organizacional y engagement laboral en docentes de educación secundaria en la región Junín (Perú). Métodos. El estudio tuvo un enfoque cuantitativo, tipo básico por su finalidad, nivel correlacional y diseño transversal y correlacional. Se emplearon dos instrumentos: el cuestionario de clima organizacional que constó de 23 ítems y cuyas dimensiones fueron liderazgo, comunicación y motivación; y el de engagement laboral que constó de 16 ítems y 3 dimensiones: vigor, dedicación y absorción. La técnica de muestreo fue no probabilística por conveniencia, y la muestra fue de 126 docentes de educación secundaria. Resultados. El 84,1 % percibió que el clima organizacional es bueno y el 69 % considera que el engagement laboral es alto. La prueba de hipótesis confirma la relación significativa entre ambas variables, puesto que el p-valor hallado fue de 0,001 y la fuerza de correlación tau-b de Kendall de 0,363, lo cual señala que existe correlación media-baja. Conclusión. Existen evidencias suficientes para afirmar que el clima organizacional tiene un nivel de incidencia menor en el engagement laboral, el cual, sin embargo, podría ser mayor si las instituciones educativas no consideran medidas preventivas

Desarrollo evolutivo de las competencias laborales: una revisión de la literatura

Objective. To identify the theoretical approaches on labor competencies in the period 2010-2021. Methodology. This research is a review article that uses as a tool the PRISMA 2009 Protocol, by means of which it was possible to select the articles according to certain criteria such as inclusion and exclusion. Results. The study conducted on labor competencies showed that during the period 2010-2021, the number of review articles increased considerably, of which 35 articles that passed through various filters were taken into account. Conclusion. It was possible to appreciate the existence of a greater elaboration of research between 2019 and 2020, giving greater emphasis to this variable, since the construct of labor competencies reveals a whole set of knowledge, skills, attitudes and experiences that determine the execution of a successful task.Objetivo. Identificar las aproximaciones teóricas sobre competencias laborales comprendidas en el periodo 2010-2021. Metodología. Esta investigación es un artículo de revisión que utiliza como herramienta el Protocolo PRISMA 2009, por medio del cual se hizo posible seleccionar los artículos de acuerdo a ciertos criterios como inclusión y exclusión. Resultados. El estudio realizado acerca de las competencias laborales demostró que durante el periodo 2010-2021, el número de artículos de revisión se incrementó considerablemente, de los cuales se tomó en cuenta 35 artículos que pasaron por diversos filtros. Conclusión. Se logró apreciar la existencia de una mayor elaboración de investigaciones entre los años 2019 y 2020, otorgando mayor énfasis a esta variable, puesto que el constructo de competencias laborales revela todo un conjunto de conocimientos, habilidades, actitudes y experiencias que determinan la ejecución de una tarea exitosa

History of Galaxy Interactions and their Impact on Star Formation over the Last 7 Gyr from GEMS

We perform a comprehensive estimate of the frequency of galaxy mergers and their impact on star formation over z~0.24--0.80 (lookback time T_b~3--7 Gyr) using 3698 (M*>=1e9 Msun) galaxies with GEMS HST, COMBO-17, and Spitzer data. Our results are: (1) Among 790 high mass (M*>=2.5e10 Msun) galaxies, the visually-based merger fraction over z~0.24--0.80, ranges from 9%+-5% to 8%+-2%. Lower limits on the major and minor merger fractions over this interval range from 1.1% to 3.5%, and 3.6% to 7.5%, respectively. This is the first approximate empirical estimate of the frequency of minor mergers at z<1. For a visibility timescale of ~0.5 Gyr, it follows that over T_b~3--7 Gyr, ~68% of high mass systems have undergone a merger of mass ratio >1/10, with ~16%, 45%, and 7% of these corresponding respectively to major, minor, and ambiguous `major or minor' mergers. The mean merger rate is a few x 1e-4 Gyr-1 Mpc-3. (2) We compare the empirical merger fraction and rate for high mass galaxies to a suite of Lambda CDM-based models: halo occupation distribution models, semi-analytic models, and hydrodynamic SPH simulations. We find qualitative agreement between observations and models such that the (major+minor) merger fraction or rate from different models bracket the observations, and show a factor of five dispersion. Near-future improvements can now start to rule out certain merger scenarios. (3) Among ~3698 M*>=1e9 Msun galaxies, we find that the mean SFR of visibly merging systems is only modestly enhanced compared to non-interacting galaxies over z~0.24--0.80. Visibly merging systems only account for less than 30% of the cosmic SFR density over T_b~3--7 Gyr. This suggests that the behavior of the cosmic SFR density over the last 7 Gyr is predominantly shaped by non-interacting galaxies.Comment: Accepted for Publication in the Astrophysical Journal. 17 pages of text, 21 figures, 3 tables. Uses emulateapj5.st

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum