Comparison of vibration and rolling noise emission of resilient and solid monobloc railway wheels in underground lines

Flat or worn wheels rolling on rough or corrugated tracks can provoke airborne noise and ground-borne vibration, which can be a serious concern for nearby neighbours of urban rail transit lines. Among the various treatments used to reduce vibration and noise, resilient wheels play an important role. In conventional resilient wheels, a slightly prestressed V­shaped rubber ring is mounted between the steel wheel centre and tyre. The elastic layer enhances rolling noise and vibration suppression, as well as impact reduction on the track. In this paper the effectiveness of resilient wheels in underground lines, in comparison to monobloc ones, is assessed. The analysed resilient wheel is able to carry greater loads than standard resilient wheels used for light vehicles. It also presents a greater radial resiliency and a higher axial stiffness than conventional V­wheels. The finite element method was used in this study. A quarter car model was defined, in which the wheelset was modelled as an elastic body. Several simulations were performed in order to assess the vibrational behaviour of elastic wheels, including modal, harmonic and random vibration analysis, the latter allowing the introduction of realistic vertical track irregularities, as well as the influence of the running speed. Due to numerical problems some simplifications were needed. Parametric variations were also performed, in which the sensitivity of the whole system to variations of rubber prestress and Poisson’s ratio of the elastic material was assessed.Results are presented in the frequency domain, showing a better performance of the resilient wheels for frequencies over 200 Hz. This result reveals the ability of the analyzed design to mitigate rolling noise, but not structural vibrations, which are primarily found in the lower frequency range

Síntesis sobre Bioética

En la actualidad, el desarrollo de la ciencia y de manera especial el campo de la investigación científica, requiere una actuación apegada a principios éticos que garanticen la integridad del ser humano a fin de promover una mejor calidad de vida

Techno-economic Analysis of Biomass to Fischer-tropsch Diesel Production with and without CCS Under Norwegian Conditions

AbstractThis article deals with techno-economic analysis for production of transportation liquid fuel from biomass (biomass to liquid - BTL fuel) under Norwegian conditions, via thermal gasification followed by Fischer-Tropsch (FT) synthesis, integrated with combined heat and electricity production. The production plant is fuelled by 150 MW (LHV basis) of biomass in the form of raw woodchips or torrefied woodchips. The plant design is based on high temperature entrained flow gasification followed by catalytic Fischer-Tropsch synthesis. The plant efficiency based on FT-crude efficiency, thermal power efficiency, and electrical efficiency was predicted for two cases: with and without carbon capture and storage (CCS). In addition, it was also estimated for the production cost of FT-crude in terms of ($/GJ) in various plant operating conditions with varied feedstock quality, gasification temperature, and gasification equivalence ratio

El aprendizaje del voleibol basado en el juego en Educación Física y su efecto sobre variables motivacionales situacionales

El objetivo de este estudio fue evaluar la eficacia de una intervención en una unidad didáctica de voleibol en Educación Física sobre distintas variables motivacionales situacionales con dos niveles de intervención. Un primer nivel aplicando estrategias generales relativas a las áreas TARGET (Ames, 1992), y un segundo nivel de intervención desarrollando metodológicamente el uso de los Teaching Games for Understanding (Bunke, y Thorpe, 1982). En el estudio participaron 61 alumnos de 4º curso de Educación Secundaria Obligatoria, en una unidad didáctica completa. En el grupo experimental (n= 41) se aplicó una intervención específica, mientras que en el grupo control (n= 20) no hubo ningún tipo de manipulación, con un enfoque más tradicional de enseñanza. Los instrumentos utilizados midieron el clima motivacional, soporte de autonomía, necesidades psicológicas básicas y motivación autodeterminada. Los resultados mostraron en el grupo experimental, respecto al grupo control, una mayor percepción del clima tarea, mayor soporte de autonomía, mayor satisfacción de la autonomía y menor desmotivación. Los resultados muestran como los enfoques centrados en el alumnado a través de la enseñanza basada en el juego generan climas motivacionales óptimos lo cual puede repercutir de forma positiva en las clases de Educación Física.The aim of this study was to evaluate the effectiveness of a volleyball teaching unit program of Physical Education over situational motivational variables, with two levels of intervention. A first level by applying general strategies based on TARGET areas (Ames, 1992) , and a second level of intervention methodically based on the Teaching Games for Understanding (Bunker and Thorpe, 1982) approach. The effect of the intervention on different situational motivational variables was evaluated. 61 students of the 4th year of Secondary Education were involved in a complete teaching unit. In the experimental group (n = 41) a specific intervention was applied, while in the control group (n = 20) there was no manipulation with a more traditional approach to teaching. The instruments measured the motivational climate, autonomy support, basic psychological needs and self-determined motivation. Results showed that experimental group developed a higher perceived task climate, greater autonomy, greater autonomy satisfaction and lower amotivation than the control group. Results also showed that studentcentered approaches to teaching through game-based methodology generate optimal motivational climates which can impact positively on PE classes

Shared risk factors for COVID-19 and preeclampsia in the first trimester: An observational study

Coronavirus disease 2019; First trimester; PreeclampsiaCoronavirus 2019; Primer trimestre; PreeclàmpsiaCoronavirus 2019; Primer trimestre; PreeclampsiaIntroduction: The association between preeclampsia and coronavirus disease 2019 (COVID-19) is under study. Previous publications have hypothesized the existence of shared risk factors for both conditions or a deficient trophoblastic invasion as possible explanations for this association. The primary aim of this study was to examine baseline risk factors measured in the first-trimester combined screening for preeclampsia in pregnant women with COVID-19 compared with the general population. A secondary aim of this study was to compare risk factors among patients with mild and severe COVID-19. Material and methods: This was an observational retrospective study conducted at Vall d'Hebron Hospital Campus (Catalonia, Spain). Study patients were 231 pregnant women undergoing the first-trimester screening for preeclampsia and positive for severe acute respiratory syndrome coronavirus 2 between February 2020 and September 2021. The reference cohort were 13 033 women of the general population from six centers across Catalonia from May 2019 to June 2021. Based on the need for hospitalization, patients were classified in two groups: mild and severe COVID-19. First-trimester screening for preeclampsia included maternal history, mean arterial blood pressure, mean uterine artery pulsatility index (UtAPI), placental growth factor (PlGF), and pregnancy-associated plasma protein-A (PAPP-A). Results: The proportion of cases at high risk for preeclampsia was significantly higher among the COVID-19 group compared with the general population (19.0% and 13.2%, respectively; p = 0.012). When analyzing risk factors for preeclampsia individually, women with COVID-19 had higher median body mass index (25.2 vs 24.5, p = 0.041), higher UtAPI multiple of the median (MoM) (1.08 vs 1.00, p < 0.001), higher incidence of chronic hypertension (2.8% vs 0.9%, p = 0.015), and there were fewer smokers (5.7% vs 11.6%, p = 0.007). The MoMs of PlGF and PAPP-A did not differ significantly between both groups (0.96 vs 0.97, p = 0.760 and 1.00 vs 1.01, p = 0.432; respectively). Conclusions: In patients with COVID-19, there was a higher proportion of women at high risk for preeclampsia at the first-trimester screening than in the general population, mainly because of maternal risk factors, rather than placental signs of a deficient trophoblastic invasion

Clinical effectiveness of routine first-trimester combined screening for pre-eclampsia in Spain with the addition of placental growth factor

Aspirin; Placental growth factor; Pre-eclampsiaAspirina; Factor de crecimiento placentario; PreeclampsiaAspirina; Factor de creixement placentari; PreeclampsiaIntroduction Pre-eclampsia affects 2%–8% of pregnancies and is one of the leading causes of maternal and perinatal morbidity and mortality. First-trimester screening using an algorithm that combines maternal characteristics, mean arterial blood pressure, uterine artery pulsatility index and biomarkers (pregnancy-associated plasma protein-A and placental growth factor) is the method that achieves a greater diagnostic accuracy. It has been shown that daily salicylic acid administration before 16 weeks in women at a high risk for pre-eclampsia can reduce the incidence of preterm pre-eclampsia. However, no previous studies have evaluated the impact of routine first-trimester combined screening for pre-eclampsia with placental growth factor after being implemented in the clinical practice. Material and methods This was a multicenter cohort study conducted in eight different maternities across Spain. Participants in the reference group were prospectively recruited between October 2015 and September 2017. Participants in the study group were retrospectively recruited between March 2019 and May 2021. Pre-eclampsia risk was calculated between 11+0 and 13+6 weeks using the Gaussian algorithm combining maternal characteristics, mean arterial pressure, uterine arteries pulsatility index, pregnancy-associated plasma protein-A and placental growth factor. Patients with a risk greater than 1/170 were prescribed daily salicylic acid 150 mg until 36 weeks. Patients in the reference group did not receive salicylic acid during gestation. Results A significant reduction was observed in preterm pre-eclampsia (OR 0.47; 95% CI: 0.30–0.73), early-onset (<34 weeks) pre-eclampsia (OR 0.35; 95% CI: 0.16–0.77), preterm small for gestational age newborn (OR 0.57; 95% CI: 0.40–0.82), spontaneous preterm birth (OR 0.72; 95% CI: 0.57–0.90), and admission to intensive care unit (OR 0.55; 95% CI: 0.37–0.81). A greater treatment adherence resulted in a significant reduction in adverse outcomes. Conclusions Routine first-trimester screening for pre-eclampsia with placental growth factor leads to a reduction in preterm pre-eclampsia and other pregnancy complications. Aspirin treatment compliance has a great impact on the effectiveness of this screening program

Biocontrol de Rhizoctonia solani en cultivo de frijol, mediante aislamiento de Trichoderma spp. a nivel de invernadero

El presente trabajo de investigación se realizó en el Laboratorio e Invernadero del Departamento de Protección Vegetal, Facultad de Ciencias Agronómicas, Universidad de El Salvador, en los meses de febrero a mayo de 1995. El propósito fue evaluar el Biocontrol de Rhizoctonia solani Kunh en el cultivo de frijol, mediante aislamientos de Trichoderma spp a nivel de invernadero para lo cual fue necesario desarrollar dos fases. Una a nivel de laboratorio, que consistió en la obtención de colonias puras de R. solani y Trichoderma spp. en P.D.A. así como la realización de cuatro pruebas previas al establecimiento del ensayo; en la primera, se comprobó la patogenicidad de R. solani, resultando que, de 60 semillas de frijol colocadas en el sustrato inoculado, el 93.33% fueron atacadas por el patógeno y 6.66% emergió sin daños. Simultáneamente se comprobó que el período de incubación del hongo por espacio de 8, 12 y 14 días producía efectos semejantes. La segunda prueba demostró la agresividad de Trichoderma spp. frente a R. solani pues de 25 semillas cubiertas con conidios de Trichoderma spp. y colocadas en el sustrato inoculado con el hongo patógeno, el 92% emergió normalmente. La tercera prueba consistió en verificar la inocuidad de Trichoderma spp. en el cultivo de frijol, para lo cual se colocaron 50 grs. de cultivo puro del hongo antagonista en el sustrato de 4 macetas, posteriormente se colocaron 32 semillas, cuyo desarrollo no fue inhibido por el hongo, obteniéndose un 100% de emergencia. En la cuarta prueba se observó la agresividad de Trichoderma spp. frente a R. solani in vitro. Se colocaron 4 cajas Petri, conteniendo 20 g. de P.D.A. más 1 cm2 de cultivo puro de R. solani en un extremo y en el otro extremo, 1 cm2 de Trichoderma spp; se monitoreó por espacio de 108 horas, comprobándose un claro control sobre el patógeno. En la segunda fase, a nivel de invernadero tanto el hongo antagonista Trichoderma spp, como el hongo fitopatógeno R. solani fueron probados en cultivo de frijol y comparado el efecto biocontrolador con los resultados producidos por productos químicos (Tolclofosmetyl y Carboxin) en el combate del "mal del talluelo" producido por Rhizoctonia solani. Se usó el diseño estadístico totalmente al azar, con 4 tratamientos y seis repeticiones, compuesto por 120 unidades experimentales, cada una de las cuales constaba de una bolsa de polietileno negro conteniendo 6.7 5 lbs. de suelo esterilizado más cuatro semillas de frijol, variedad DOR-482, así como los tratamientos respectivos. De acuerdo a los resultados obtenidos se concluye que en los parámetros bajo estudio: porcentaje de germinación, plan tas sanas, plantas sobrevivientes y vigorosas; el tratamiento Tolclofosmetyl (T1) fue el mejor, en el orden de efectividad le siguieron: el tratamiento Trichoderma spp (T3), el testigo (T4) y el tratamiento Carboxin (T2) al efectuar comparaciones con relación al testig

Metodologías innovadoras e inclusivas en educación secundaria: los grupos interactivos y la asamblea de aula

In a context where diversity is the defining word, it has been proved possible taking advantage of that diversity as a powerful educational tool instead of considering it an obstacle. Two met hodologies, interactive groups and group assemblies, make students work toget her and change certain mistaken points of view. Interactive groups enable our students to work together the same activities and contents; each one may contribute with his or her capacities to the joint process of solving a task. Group assemblies foster dialogue and commitment. Both of them build a broader and stronger school.En un contexto en el que la diversidades la palabra clave, en lugar de considerarla un obstáculo, ha sido posible aprovechar dicha diversidad como una herramienta educativa poderosa. Dos met odologías, los grupos interactivos y las asambleas de aula, logran que los estudiantes trabajen juntos y cambien puntos de vista erróneos. Los grupos interactivos permiten a nuestros alumnos trabajar juntos las mismas actividades y contenidos; cada uno contribuye con sus propias capacidades al proceso conjunto de resolución dela tarea. Las asambleas de aula fomentan el diálogo y el compromiso. Ambas metodologías construyen una escuela de éxito y de calidad