Desarrollo del razonamiento sobre pruebas de significación de estudiantes de bachillerato en un ambiente tecnológico

Se describe el desarrollo del razonamiento de 36 estudiantes de bachillerato, organizados en parejas, acerca de la técnica de pruebas de significación estadística con el apoyo de un software educativo de estadística (Fathom); dicho desarrollo es visto a través de sus respuestas a 4 problemas de pruebas de significación; estos se resolvieron en sendas sesiones en las que además se realizaron cortas intervenciones del profesor, se enseñó a utilizar el software y se discutieron dudas de los problemas vistos en la sesión previa respectiva. Las respuestas a cada problema se clasificaron en niveles SOLO. Los resultados muestran avances en la calidad de las respuestas de los participantes, superándose en cada actividad algunos errores cometidos en la previa, esto lleva conjeturar que los estudiantes se van apropiando del esquema de pruebas de significación. No obstante, se presentan algunas dificultades similares a las ya reportadas en la literatura

An iterated greedy heuristic for a market segmentation problem with multiple attributes

[EN] A real-world customer segmentation problem from a beverage distribution firm is addressed. The firm wants to partition a set of customers, who share geographical and marketing attributes, into segments according to certain requirements: (a) customers allocated to the same segment must have very similar attributes: type of contract, type of store and the average difference of purchase volume; and (b) compact segments are desired. The main reason for creating a partition with these features is because the firm wants to try different product marketing strategies. In this paper, a detailed attribute formulation and an iterated greedy heuristic that iteratively destroys and reconstructs a given partition are proposed. The initial partition is obtained by using a modified k-means algorithm that involves a GRASP philosophy to get the initial configuration of centers. The heuristic includes an improvement method that employs two local search procedures. Computational results and statistical analyses show the effectiveness of the proposed approach and its individual components. The proposed metaheuristic is also observed very competitive, faster, and more robust when compared to existing methods. (C) 2017 Elsevier B.V. All rights reserved.This research has been supported by the Mexican National Council for Science and Technology (CONACYT) through grants CB2005-01-48499Y and CB2011-01-166397, and a scholarship for graduate studies, and by the Universidad Autonoma de Nuevo Leon through its Scientific and Technological Research Support Program (PAICYT), grants CA1478-07, CE012-09, IT511-10, and CE331-15. Ruben Ruiz is partially supported by the Spanish Ministry of Economy and Competitiveness, under the project "SCHEYARD - Optimization of Scheduling Problems in Container Yards" (No. DPI2015-65895-R) financed by FEDER funds. We would like to thank Rafael Frinhani, Richard Fuchshuber, and their corresponding research teams for providing us the source code of their algorithms to carry out the corresponding tests. Furthermore, we are grateful to the editor and the four anonymous reviewers for their careful reading of our manuscript and their constructive comments and suggestions which helped us improve its quality.Huerta-Muñoz, D.; Ríos-Mercado, RZ.; Ruiz García, R. (2017). An iterated greedy heuristic for a market segmentation problem with multiple attributes. European Journal of Operational Research. 261(1):75-87. https://doi.org/10.1016/j.ejor.2017.02.013S7587261

Los depósitos de sulfuros masivos vulcanogénicos (VMS) de la cuenca Lancones Piura - Perú

La Cuenca Lancones se encuentra ubicada en la región noroccidental del Perú, en el Departamento de Piura y en el borde oriental de la Franja Costanera, su límite oeste lo constituye el Macizo de Amotapes y hacia el este la región pre-cordillerana de la Cordillera Occidental de los Andes. Esta cuenca se extiende hacia Ecuador, en donde se la ha denominado Cuenca Celica. (Ver Fig. 1) La Cuenca Lancones de acuerdo a las características geológicas, mineralógicas y litológicas debe ser considerada como el principal objetivo en la prospección por yacimientos vulcanogénicos de sulfuros masivos (VMS) en el Perú (Ríos, 2004). Actualmente el yacimiento de Tambo Grande, situado dentro de la Cuenca Lancones, cuenta con tres depósitos de sulfuros masivos (TG1, TG3 y B5), considerados como depósitos de clase mundial (Tegart, 2000)

Tratamiento ortodóntico quirúrgico de canino maxilar impactado con reabsorción radicular bilateral: Reporte de caso

Los dientes caninos superiores permanentes impactados bilaterales son un problema clínico que puede provocar una serie de secuelas irreversibles como la reabsorción radicular de dientes vecinos. Se describe el caso de una paciente con ausencia clínica de caninos superiores que se encontraban impactados orientados hacia vestibular produciendo reabsorción de los dos tercios de la raíces de todos los incisivosSuperiores,los que fueron extraídos, en el mismo acto se realizó la exposición quirúrgica de los dos dientes caninos y posteriormente la tracción ortodontica de los caninos impactados, en el maxilar inferior se realizaron extracción de primeras premolares inferiores para compensar las extracciones que se realizaron en el maxilar superior.Ocho meses fueron necesarios para observar clínicamente las piezas impactadas. El tiempo de tratamiento fue de 2 años, al finalizar el tratamiento ortodoncicose realizó una ameloplastia de las cúspides de los caninos para dar forma de incisivos laterales.The that were impacted oriented vestibular reabsorption producing 2/3 root of the upper incisors, they were extracted, with subsequent surgical exposure and orthodontic traction of the impacted canines in the lower jaw were made first premolars extraction, Camouflaging the alveolar biprotrusión. Eight months were required to observe clinically impacted teeth. The treatment time was 2 years old are ameloplastia cusps of the canines to build incisal edge

Análisis comparativo: entrevista realista de selección, satisfacción en el trabajo e intención de permanencia

El presente trabajo extiende el estudio de Littlewood et al. (2005) al comparar las variables de entrevista realista de selección (ERS), satisfacción en el trabajo (ST) y la intención de permanencia en la organización (IP) en una muestra de 162 estudiantes de licenciatura y 258 de maestría. Se utilizó un cuestionario con 26 preguntas, se obtuvieron niveles de confiabilidad superiores a 0.60, y se encontró que sí existen diferencias estadísticamente significativas en las variables ERS e IP, pero no en el nivel de ST

Enhancing shoot recovery from transgenic avocado somatic embryos

Use of biotechnological tools in avocado (Persea americana Mill.) is hampered by difficulties in obtaining mature somatic embryos with an acceptable germination capacity. Use of semi-permeable cellulose acetate membranes on top of maturation medium has improved the quality of obtained embryos and their germination rate; however, in the case of transgenic embryos the conversion rate is still rather low. In this investigation, a protocol for recovery of transgenic plants has been developed. Mature avocado somatic embryos, over cellulose acetate membranes, were obtained and induced to germinate following the protocol described in Palomo-Ríos (2012). Some transgenic embryos developed buds ≤ 2 mm, which failed to elongate. For shoot recovery, cotyledons were partially removed and the embryonic axis cultured over 4 weeks in MS medium supplemented with either 1 mg/l BA, 1 mg/l TDZ or 1 mg/l BA and 1 mg/l TDZ. Highest shoot recovery was obtained in medium supplemented with 1 mg/l BA and 1 mg/l TDZ, 53.6±6.7% versus 23.2±5,7% and 39.6±6.4% in media supplemented with 1 mg/l BA or 1 mg/l TDZ, respectively. Afterwards, sprouted embryos were cultured over 4 additional weeks in MS medium supplemented with 1 mg/l BA. In some cases, resulting shoots could be induced to proliferate in GD medium (Gamborg et al., 1968) supplemented with 0.3 mg/l BA, while in other cases, they had to be recovered through micrografting onto in vitro germinated seedlings as described in Pliego-Alfaro and Murashige (1987). MS medium supplemented with 1mg/l BA and solidified with 6 g/l Sigma A-1296 agar, was used for micrografts. Shoots derived from micrografts were either induced to proliferate in GD medium with 0.3 mg/l BA or further grafted and cultured in liquid MS medium supplemented with 0.1 mg/l BA, using perlite as substrate. After 8-12 weeks, micrografts could be transferred to ex vitro conditions. References: Gamborg O.L., Muller, R.A., Iojima, K., (1968). Nutrient requirements of suspension cultures of soybean roots cells. Exp. Cell. Res. 50:151-158. Palomo-Ríos, E., (2012). Thesis: Regeneración y Transformación Genética de Aguacate (Persea americana Mill.). Ph.D. Dissertation, University of Málaga, Málaga Pliego-Alfaro, F., Murashige, T., (1987). Possible rejuvenation of adult avocado by graftage onto juvenile root stocks in vitro. Hort Sci. 22:1321-1324.AGL2011-30354-C02-0

Differences in Utilization of Lower Limb Muscle Power in Squat Jump With Positive and Negative Load

DATA AVAILABILITY STATEMENT The datasets generated for this study are available on request to the corresponding author.Jump performance is related to the ability of lower limb muscles to produce power during the push-off phase. However, it is not known if the power associated with the action of active and passive elements of the lower limb muscles change significantly in jumps with positive and negative loads. In this study, the power associated with the action of passive and active components of lower limb muscles as a whole in squat jumps (SJ) with increase and decrease in the external load is analyzed Fourteen trained male subjects (22.5 ± 2.1 years; 176.5 ± 5.4 cm; 75.8 ± 5.8 kg; BMI 24.3 ± 1.8) performed SJ on a force plate. A functional electromechanical dynamometer (FEMD) system was used to change the external load in a range of −30 to +30% of the subject’s body weight. A model comprising a mass, a spring, an active element, and a damper was used. We applied an optimization principle to determine power in center of mass (CoM) (ptot), the powers associated with active element (pact), damper (pƔ), and spring (pk) during the push-off phase. Significant differences between loading conditions for each variable were tested by repeated-measures one-way ANOVA with Bonferroni post hoc analysis, p < 0.05. Shapes of the average curves for instantaneous variation of pact, pƔ, pk, and ptot during push-off with positive loads were closer to 0% than with negative loads. As the load increased, maximum values of ptot, pƔ, and pk decreased. Only with a negative load of −30% did ptot increase significantly, this was not accompanied by changes in pact, pƔ, and pk. The load of one’s own body provides conditions for develop high pact peaks, although the maximum ptot is not achieved in that condition. The increase in negative loads produces a significant increase in ptot, but not in pact and can be interpreted as a situation in which the power delivered to the system by the action of active components is better used. The SJ with positive load, although more similar to the instantaneous changes that occur to the SJ with body weight are not gestures where high power is developed

¿Podemos hablar de sistema de Gestión de Seguridad y Salud en el Trabajo frente a los nuevos lineamientos de los estándares de la Resolución 312 de 2019?

Los sistemas de Gestión se estructuran con base en el mejoramiento continuo, direccionadodesde el proceso de Planear, Hacer, Verificar y Actuar. Cabe resaltar que, si se generaincumplimiento en este ciclo, el sistema no puede hablar de mejora, ni de sistema de gestión. Alcomparar los estándares mínimos de la Resolución 312 de 2019, para empresas de menos de50 trabajadores riesgo I, II o III se evidencia la carencia de la exigencia de esta norma alcumplimiento de la razón de ser de los sistemas de gestión.El presente artículo de opinión, busca confrontar la normatividad legal para las empresas demenos de 50 trabajadores, cuyo riesgo es I, II o III, frente al ciclo de mejoramiento continuo, otrasnormas internacionales y plantear una posición frente a dicha norma

Expression analysis of Flowering related genes in olive plants transformed with the "Medicago truncatula" FT gene MtFTa1

Olive tree (Olea europaea L.) forms inflorescences in lateral buds that flower in spring. Flowering occurs due to the presence of a mobile flower-promoting factor called florigen, the product of “FLOWERING LOCUS T” (FT). In many plants, FT and TERMINAL FLOWER 1 (TFL1) genes encode related proteins with opposite functions, i.e. FT induces flowering, while TFL1 represses it. Olive flower induction seems to be mediated by an increase in FT levels in response to cold winters. Because of climate change, warmer winters are expected, which can alter flowering time. Three olive transgenic lines containing the MtFTa1 gene from Medicago truncatula were obtained (FT5, FT7 and FT15) to study the effect of FT on flowering time (Haberman et al., 2017). The embryogenic line P1 from a seed of cv. Picual was used for transformation, and also as control (CP1). FT7 flowered continuously; FT5 did not flower and showed a dwarf branching phenotype, and FT15 had a dwarf-branching habit and developed abnormal flowers. The expression of the transgene and three endogenous genes (OeFT1, OeFT2 and OeTFL1-1) was analyzed in these juvenile plants, as well as in the control (CP1), throughout the year (autumn, winter and spring).Proyecto de Excelencia P11-AGR-7992, Junta de Andalucí