261 research outputs found

    Organizaciones burocráticas e ineficiencia X: Una revisión de modelos

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    El presente trabajo es una revisión de los principales modelos microeconómicos que han analizado el problema de la ineficiencia X en organizaciones burocráticas. A partir del trabajo seminal de Niskanen, que parte del supuesto de que existe eficiencia productiva en las organizaciones burocráticas, analizamos posteriores trabajos que modifican los supuestos iniciales de Niskanen con el objetivo de explicar la existencia de ineficiencia X en las agencias burocráticas. La conclusión a la que llegamos es que en estas organizaciones pueden existir objetivos no coherentes con la idea de eficiencia productiva. Así, para cada modelo, analizamos las implicaciones que tal comportamiento tiene sobre la ineficiencia X. Classification-JEL : D21; D73; H32.Naturaleza de la ineficiencia, ineficiencia productiva, teoría de la burocracia.

    Juego de ajedrez sobre dispositivos móviles con sistema operativo Android para personas con limitación visual

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    El proyecto surge al ver la necesidad de una aplicación para que las personas con limitación visual puedan jugar ajedrez en plataformas móviles con sistema operativo Android, además al investigar las posibilidades que brinda el mercado para satisfacer las necesidades de este tipo de personas con limitación, se evidencia que estas posibilidades son pocas, por las razones anteriormente mencionadas, y teniendo en cuenta que en la Universidad Tecnológica de Pereira, existen personas con este tipo de limitación, surge la idea de desarrollar un software sobre plataforma Android, el cual permita a los discapacitados visuales jugar ajedrez de manera remota con otras personas en el mundo y así disfrutar de uno de los juegos más practicados por los individuos con este tipo de limitación física

    El uso de ítems inversos en las escalas tipo Likert: una práctica cuestionable

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    The use of positively worded items and reversed forms aims to reduce response bias and is a commonly used practice nowadays. The main goal of this research is to analyze the psychometric implications of the use of positive and reversed items in measurement instruments. Method: A sample of 374 participants was tested aged between 18 and 73 (M=33.98; SD=14.12), 62.60% were women. A repeated measures design was used, evaluating the participants with positive, reversed, and combined forms of a self-effi cacy test. Results: When combinations of positive and reversed items are used in the same test the reliability of the test is fl awed and the unidimensionality of the test is jeopardized by secondary sources of variance. In addition, the variance of the scores is reduced, and the means differ signifi cantly from those in tests in which all items are either positive or reversed, but not combined. Conclusions: The results of this study present a trade-off between a potential acquiescence bias when items are positively worded and a potential different understanding when combining regular and reversed items in the same test. The specialized literature recommends combining regular and reversed items for controlling for response style bias, but these results caution researchers in using them as well after accounting for the potential effect of linguistic skills and the fi ndings presented in this study.Antecedentes: el uso de ítems formulados positivamente junto con otros inversos es una práctica habitual para tratar de evitar sesgos de respuesta. El objetivo del presente trabajo es analizar las implicaciones psicométricas de utilizar ítems directos e inversos en la misma prueba. Método: se utilizó una muestra de 374 participantes con edades comprendidas entre 18 y 73 años (M=33.98; DT=14.12), con un 62,60% de mujeres. Mediante un diseño de medidas repetidas se evaluó a los participantes en una prueba de autoefi cacia con tres condiciones: todos los ítems positivos, todos negativos y un combinado de ambos. Resultados: cuando se utilizan en la misma prueba tanto ítems positivos como negativos su fi abilidad se deteriora, y la unidimensionalidad de la prueba se ve comprometida por fuentes secundarias de varianza. La varianza de las puntuaciones disminuye, y las medias difi eren signifi cativamente respecto de las pruebas en las que todos los ítems están formulados positiva o negativamente. Conclusiones: los resultados de este estudio presentan una disyuntiva entre un posible sesgo de aquiescencia cuando los ítems tienen una redacción positiva y una comprensión potencialmente diferente cuando se combinan ítems regulares e invertidos en la misma prueba. La literatura especializada recomienda combinar ítems regulares e invertidos para poder controlar el sesgo del estilo de respuesta, pero estos resultados advierten a los investigadores que los usen también después de tener en cuenta el potencial efecto de las habilidades lingüísticas y de los hallazgos presentados en este estudio.This research was funded by the Spanish Association of Methodology of Behavioral Sciences and Health (AEMCCO), member of the European Association of Methodology (EAM), and by the FPI programme from the Ministry of Economy and Competitiveness of the Government of Spain (PSI2014-56114-P, BES2012-053488, and PSI2017-85724-P)

    Combining coagulation and electrocoagulation with UVA-LED photo-fenton to improve the efficiency and reduce the cost of mature landfill leachate treatment

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    Producción CientíficaThis study focused on the reduction of the treatment cost of mature landfill leachate (LL) by enhancing the coagulation pre-treatment before a UVA-LED photo-Fenton process. A more efficient advanced coagulation pretreatment was designed by combining conventional coagulation (CC) and electro-coagulation (EC). Regardless of the order in which the two coagulations were applied, the combination achieved more than 73% color removal, 80% COD removal, and 27% SUVA removal. However, the coagulation order had a great influence on both final pH and total dissolved iron, which were key parameters for the UVA-LED photo-Fenton post-treatment. CC (pH = 5; 2 g L−1 of FeCl36H2O) followed by EC (pH = 5; 10 mA cm−2) resulted in a pH of 6.4 and 100 mg L−1 of dissolved iron, whereas EC (pH = 4; 10 mA cm−2) followed by CC (pH = 6; 1 g L−1 FeCl36H2O) led to a final pH of 3.4 and 210 mg L−1 dissolved iron. This last combination was therefore considered better for the posterior photo-Fenton treatment. Results at the best cost-efficient [H2O2]:COD ratio of 1.063 showed a high treatment efficiency, namely the removal of 99% of the color, 89% of the COD, and 60% of the SUVA. Conductivity was reduced by 17%, and biodegradability increased to BOD5:COD = 0.40. With this proposed treatment, a final COD of only 453 mg O2 L−1 was obtained at a treatment cost of EUR 3.42 kg COD−1.Ministerio de Economía, Industria y Competitividad (CTM2016-77948-R)Comunidad de Madrid - Project RETOPROSOST-2 (S2018/EMT-4459

    UVA-LED technology’s treatment efficiency and cost in a competitive trial applied to the photo-fenton treatment of landfill leachate

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    Producción CientíficaThe objective of this trial was to assess the application of UVA-LED technology as an alternative source of irradiation for photo-Fenton processes, aiming to reduce treatment costs and provide a feasible treatment for landfill leachate. An optimized combination of coagulation with ferric chloride followed by photo-Fenton treatment of landfill leachate was optimized. Three different radiation sources were tested, namely, two conventional high-pressure mercury-vapor immersion lamps (100 W and 450 W) and a custom-designed 8 W 365 nm UVA-LED lamp. The proposed treatment combination resulted in very efficient degradation of landfill leachate (COD removal = 90%). The coagulation pre-treatment removed about 70% of the COD and provided the necessary amount of iron for the subsequent photo-Fenton treatment, and it further favored this process by acidifying the solution to an optimum initial pH of 2.8. The 90% removal of color improved the penetration of radiation into the medium and by extension improved treatment efficiency. The faster the Fenton reactions were, as determined by the stoichiometric optimum set-up reaction condition of [H2O2]0/COD0 = 2.125, the better were the treatment results in terms of COD removal and biodegradability enhancement because the chances to scavenge oxidant agents were limited. The 100 W lamp was the least efficient one in terms of final effluent quality and operational cost figures. UVA-LED technology, assessed as the application of an 8 W 365 nm lamp, provided competitive results in terms of COD removal, biodegradability enhancement, and operational costs (35–55%) when compared to the performance of the 450 W conventional lamp.Ministerio de Economía, Industria y Competitividad - (project CTM2016- 77948-R)Comunidad Autónoma de Madrid - (project S2018/EMT-4459

    Aviation-associated spatial disorientation and incidence of visual illusions survey in military pilots

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    The lack of information on active military pilots has led to the present study, which aimed to analyze the sense of aviation-associated spatial disorientation and the incidence of visual illusions of fighter and transport military pilots through a post-flight survey. The advance of aeronautics has led to further aircraft developments, increasing heights and speeds which increase the psychophysiological demands, thus leading to greater incidence of spatial disorientation and visual illusions.60 male pilots with large professional experience (1012 h ± 250 accumulated flying hours) between 7 and 18 years in their respective units and experience in international missions in the current conflict areas as Lebanon, Afghanistan, Bosnia, Kosovo, and Iraq, were subjected to a post-flight visual experience questionnaire. Our findings suggest that transport pilots tend to present significant higher disorientation situations than fighter pilots, while fighter pilots presented greater sense of aviation-associated spatial disorientation but experimented more visual illusions. These differences are related with the demands of the different aircrafts used by each pilot, thus specific, individualized and larger simulated training sessions in simulated environments are suggested. Further research should focus on the analysis of peripheral and central fatigue as constructs that may help to the appearance of greater spatial disorientation and visual illusions

    Assessing an integral treatment for landfill leachate reverse osmosis concentrate

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    Producción CientíficaAn integral treatment process for landfill leachate reverse osmosis concentrate (LLROC) is herein designed and assessed aiming to reduce organic matter content and conductivity, as well as to increase its biodegradability. The process consists of three steps. The first one is a coagulation/flocculation treatment, which best results were obtained using a dosage of 5 g L−1 of ferric chloride at an initial pH = 6 (removal of the 76% chemical oxygen demand (COD), 57% specific ultraviolet absorption (SUVA), and 92% color). The second step is a photo-Fenton process, which resulted in an enhanced biodegradability (i.e., the ratio between the biochemical oxygen demand (BOD5) and the COD increased from 0.06 to 0.4), and an extra 43% of the COD was removed at the best trialed reaction conditions of [H2O2]/COD = 1.06, pH = 4 and [H2O2]/[Fe]mol = 45. An ultra violet-A light emitting diode (UVA-LED) lamp was tested and compared to conventional high-pressure mercury vapor lamps, achieving a 16% power consumption reduction. Finally, an optimized 30 g L−1 lime treatment was implemented, which reduced conductivity by a 43%, and the contents of sulfate, total nitrogen, chloride, and metals by 90%. Overall, the integral treatment of LLROC achieved the removal of 99.9% color, 90% COD, 90% sulfate, 90% nitrogen, 86% Al, 77% Zn, 84% Mn, 99% Mg, and 98% Si; and significantly increased biodegradability up to BOD5/COD = 0.4.Ministerio de Economía, Industria y Competitividad (Proyecto CTM2016-77948-R)Comunidad Autónoma de Madrid - (Proyecto (S2018/EMT-4459

    Conocimiento tradicional, cultivo y aprovechamiento del maguey pulquero en municipios de Puebla y Tlaxcala

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    La relación maguey- hombre mesoamericano data de hace 10 mil años y el aprovechamiento de la planta para la elaboración de pulque se remonta varios milenios. Esta agroindustria que floreció en el último tercio del siglo XIX, ha venido a menos lo que pone en riesgo este aprovechamiento tradicional y otros más rentables como la producción de inulina y el jarabe de fructosa con gran demanda en el mercado internacional. Se documentó y comparó el aprovechamiento del maguey pulquero en localidades de cuatro municipios de Puebla y Tlaxcala, seleccionadas con un muestreo aleatorio estratificado. Los datos taxonómicos, socioeconómicos, de gestión y actividades propias de productores, tlachiqueros y consumidores, se recabaron mediante entrevistas estructuradas y observación participativa. Los miembros de este último eslabón fueron seleccionados con un muestreo aleatorio simple. Los resultados mostraron siete tipos de magueyes, en superficies promedios de tres ha imbricados con cultivos de maíz, cebada y haba, de los cuales se describen las labores culturales y las actividades propias de los productores. El aprovechamiento sustantivo fue la elaboración del pulque, a partir de magueyes de 10 a 14 años de madurez. El cultivo y aprovechamiento se han mantenido a través de los años. Las herramientas utilizadas para la producción, transporte de aguamiel y elaboración de pulque han sido sustituidas por materiales más resistentes y duraderos, que no necesariamente han mejorado el proceso y calidad del pulque. La duración del ciclo del cultivo, la poca demanda de pulque, la baja rentabilidad económica y la ausencia de normas de protección de la planta, han provocado la disminución de la superficie de cultivo del maguey y la erosión del conocimiento del cultivo y su aprovechamiento; así, de mantenerse esa tendencia, la desaparición del maguey pulquero será inevitable.La permanencia del maguey pulquero dependerá de las acciones llevadas a cabo en conjunto por las autoridades correspondientes, los miembros de la cadena productiva e investigadores, mediante la implementación de programas que incentiven el interés e incremento del cultivo de esta planta; porque si no hay maguey, “no hay árbol de las maravillas”

    Observation of second sound in a rapidly varying temperature field in Ge

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    Second sound is known as the thermal transport regime where heat is carried by temperature waves. Its experimental observation was previously restricted to a small number of materials, usually in rather narrow temperature windows. We show that it is possible to overcome these limitations by driving the system with a rapidly varying temperature field. This effect is demonstrated in bulk Ge between 7 kelvin and room temperature, studying the phase lag of the thermal response under a harmonic high frequency external thermal excitation, addressing the relaxation time and the propagation velocity of the heat waves. These results provide a new route to investigate the potential of wave-like heat transport in almost any material, opening opportunities to control heat through its oscillatory nature.Comment: After careful revision we have ruled out the presence of coherent noise and from any other noise source within the reported data. We have updated the manuscript providing a detailed analysis of the photoreflectance signal, demonstrating with experiments its thermal origi

    Laparoscopic vs. Open Approach in Emergent Inguinal Hernia: Our Experience and Review of Literature

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    There is currently no consensus or homogeneous recommendation about the role of the laparoscopic approach in emergent inguinal hernia surgery. The aim of this manuscript is showing our experience and results of laparoscopic approach for emergent groin hernia repair comparing with open approach. A retrospective review of a prospectively maintained database between January 2011 and December 2021 of acute incarcerated groin hernia that were operated at Virgen del Rocio University Hospital. In this period, they were identified 463 patients with groin hernia that required an emergency repair. 454 patients underwent open surgery (group 1) and 36 patients underwent laparoscopic approach (TAPP procedure) (group 2). Median length stay was 1 day in lap group and 2 days in open approach. Reintervention was necessary in 20 cases (4.40%) from group 1 and one (2.27%) from group 2. In laparoscopic approach, no mortality was described but in open approach, 10 patients (2.20%) died. Globally, 58 cases (12.77%) from group 1 and six patients (16.66%) from group 2 presented any complication. Wound infection was higher in group of open repairs (5.94% vs. 2.77%). Non-surgical complications were higher in open approach (19 vs. 0). There is no statistical significance in any of these items. Laparoscopic approach is a safe, feasible and effective therapeutic option for the treatment of incarcerated groin hernia that require emergency surgery, but prospective and randomized comparative studies are needed to establish the best approach
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