COMPORTAMIENTO FISIOLÓGICO POSTCOSECHA DE TALLOS FLORALES DE ROSA (Rosa hybrida L.) EN RESPUESTA AL FÓSFORO APLICADO EN PRECOSECHA

Durante el crecimiento y desarro- llo de las flores, la nutrición fosforada es un factor que puede influir en la vida en flore- ro. El objetivo de este trabajo fue evaluar el efecto de cinco niveles de fósforo (P): 0, 0.5, 1.0, 1.5 y 2.0 me·L-1 de P aplicados en precosecha, mediante un sistema hidropóni- co abierto, en el comportamiento fisiológico postcosecha de tallos florales de rosa (Rosa hybrida L.) ‘Classy’ y ‘Vega’. Las variables evaluadas durante la vida de florero de los tallos florales fueron: transpiración foliar y floral, potencial de turgencia foliar y de pétalos. Además, se evaluó la concentración de antocianinas en pétalos al momento de la cosecha. Las aplicaciones de P en precose- cha tuvieron efecto significativo únicamente en la transpiración foliar; sin embargo, se demostró que la mayor vida en florero (15.8 días) de ‘Classy’ en comparación con ‘Vega’ (11.7 días) estuvo directamente asociada con mayores potenciales de turgencia foliar y de pétalos, mayor tasa transpiratoria floral y menor tasa transpiratoria foliar en ‘Classy’

Scaling Factor Estimation Using Optimized Mass Change Strategy, Part 2: Experimental Results

The mass change method is used to estimate the scaling factors, the uncertainty is reduced when, for each mode, the frequency shift is maximized and the changes in the mode shapes are minimized, which in turn, depends on the mass change strategy chosen to modify the dynamic behavior of the structure. On the other hand, the aforementioned objectives are difficult to achieve for all modes simultaneously. Thus, a study of the number, magnitude and location of the masses must be performed previously to the modal tests. In this paper, the mass change method was applied to estimate the scaling factors of a steel cantilever beam. The effect of the mass change strategy was experimentally studied by performing several modal tests in which the magnitude, the location and the number of the attached masses were change

Para asombrarse y aprender

Este trabajo presenta la fundamentación, diseño y resultados de un proyecto realizado en el marco de un programa institucional en la UNAM, relacionado con la innovación de la enseñanza experimental. Como producto de este proyecto se elaboró un libro con 30 experimentos de aula dirigidos a profesores de los niveles bachillerato y universitario. Los experimentos elaborados presentan propuestas experimentales novedosas que nos permitan reconceptualizar y diversificar el trabajo práctico

Effect of water activity in tortilla and its relationship on the acrylamide content after frying

The objective of this study was to relate the tortilla minimum integral desorption entropy with acrylamide content during processing of tortilla chips. Tortilla pieces were stored at 30 °C at aw of 0.11-0.84 for 4 days and fried later in soybean oil at 180 °C for 25 s. The lowest acrylamide content was observed in tortilla chips made of non-stored tortilla (aw = 0.98) as well as in those prepared from tortilla stored in the minimum integral entropy (aw = 0.53). In addition, the color and texture values were similar in both cases. These results suggest that the reduction of the acrylamide content during processing of tortilla chips and other tortilla based foods thermally processed might be modified by factors such as moisture content, aw, and the physical state of water in the tortilla. Thus, the minimum integral entropy showed to be a reliable indicator to establish the most appropriate moisture conditions to obtain tortilla chips with reduced level of acrylamide when tortilla is dehydrated. © 2014 Elsevier Ltd. All rights reserved.We are indebted to Juan Veles, Edmundo Gutierrez, Carlos Alberto Ávila, Araceli Mauricio and Veronica Flores from CINVESTAV Querétaro for their technical assistance.Peer Reviewe

Q-band 4-state phase shifter in planar technology: Circuit design and performance analysis

A 30% bandwidth phase shifter with four phase states is designed to be integrated in a radio astronomy receiver. The circuit has two 90° out-of-phase microwave phase-shifting branches which are combined by Wilkinson power dividers. Each branch is composed of a 180° phase shifter and a band-pass filter. The 180° phase shifter is made of cascaded hybrid rings with microwave PIN diodes as switching devices. The 90° phase shift is achieved with the two band-pass filters. Experimental characterization has shown significant results, with average phase shift values of -90.7°, -181.7°, and 88.5° within the operation band, 35–47 GHz, and mean insertion loss of 7.4 dB. The performance of its integration in a polarimetric receiver for radio astronomy is analyzed, which validates the use of the presented phase shifter in such type of receiver.This work was supported by the Ministerio de Economía y Competitividad, Spain, under the CONSOLIDER-INGENIO 2010 programme under the Reference No. CSD2010-00064

Octave bandwidth hybrid-coupled microstrip diplexer for a broadband radio astronomy receiver

A new octave bandwidth high selectivity compact microstrip diplexer working in the band from 10 to 20 GHz is presented, intended to be a part of an electro-optical interferometer covering the whole frequency band. The circuit is based on the combination of hybrid couplers and bandpass filters both on the microstrip technology. The diplexer provides two output frequency bands which cover the 10–14 GHz (relative bandwidth of 33%) and the 16–20 GHz (relative bandwidth of 22%) ranges, respectively, with a stop band in between from 14 to 16 GHz. Measured results show a insertion loss level of 3.3 dB for both output bands and high selectivity performance, exhibiting a rejection level between output bands higher than 20 dB and return loss better than 10 dB in all ports.This work has been funded by the Spanish Ministry of Economy, Industry and Competitiveness under Grant No. ESP2015-70646-C2-2-R

Recreational water skiing in people with paraplegia: A study of three cases

Objetivos: se analizaron la condición cardiorrespiratoria y la intensidad de esfuerzo durante la práctica recreativa del esquí náutico de slalom. Metodología: participaron tres esquiadores náuticos con paraplejia moderadamente activos. Realizaron un test incremental en un ergómetro de brazos para determinar su VO2pico y los umbrales ventilatorios y completaron 3 sesiones de práctica de esquí náutico, separadas por 48h, registrándose la FC cada 5 s. Resultados: obtuvieron un VO2pico de 22,3 ± 0,6 mL·kg-1·min-1 y los umbrales ventilatorios se analizaron al ~80 y ~50% del VO2pico. La FC media en las sesiones de esquí náutico fue de 111 ppm, lo que representó una intensidad de ~45% de la FC de reserva (FCR), permaneciendo por encima del 40% de la FCR ~12 min. Conclusión: la intensidad moderada de la práctica recreativa de esquí náutico de slalom podría servir para mantener o mejorar la condición cardiorrespiratoria en estas tres personas con paraplejiaObjectives: the cardiorespiratory fitness and the intensity of effort were analyzed during the recreational practice of slalom water skiing. Methodology: three moderately active water skiers with paraplegia participated. They performed an incremental test on an arm ergometer to determine their VO2peak and ventilatory thresholds and completed 3 sessions of water skiing, separated by 48h, where the HR was recorded every 5 s. Results: they obtained a VO2peak of 22.3 ± 0.6 mL·kg-1·min-1 and the ventilatory thresholds were analyzed at ~80 and ~50% of the VO2peak. The average heart rate in the water ski sessions was 111 bpm, which represented an intensity of ~45% of the heart rate reserve (HRR), remaining above 40% of the HRR ~12 min. Conclusion: the moderate intensity of recreational slalom skiing could serve to maintain or improve the cardiorespiratory fitness in these three people with paraplegi

Enrichment Cultures should be performed in the detection of Bacterial Oral Human Pathogens in DUWLs

Water delivered by dental units during routine dental practice is densely contaminated by bacteria. The aim of this study was to determine actual isolation of the microorganisms sprayed from Dental Unit Water Lines (DUWLs) when enrichment cultures are performed and to compare frequencies with those obtained without enrichment cultures. Moreover, the antimicrobial susceptibilities of the microorganisms isolated were also studied. Water samples were collected from one hundred dental equipments in use at Dental Hospital of our University in order to evaluate the presence/absence of microorganisms and to perform their presumptive identification. Aliquots from all of the samples were inoculated in eight different media including both enrichment and selective media. Minimal inhibitory concentrations (MIC) were determined by the broth dilution method. The results herein reported demonstrate that most of the DUWLs were colonized by bacteria from human oral cavity; when enrichment procedures were applied the percentage of DUWLs with detectable human bacteria was one hundred percent. The results showed that in order to evaluate the actual risk of infections spread by DUWLs the inclusion of a step of pre-enrichment should be performed. The need for devices preventing bacterial contamination of DUWLs is a goal to be achieved in the near future that would contribute to maintain safety in dental medical assistance

BIOMECHANICAL ASSESSMENT OF AERODYNAMIC RESISTANCE IN PROFFESSSIONAL CYCLISTS: METHODOLOGICAL ASPECTS

The aim of this study was to measure and compare the aerodynamic resistance (RA) in five different professional road cyclists obtained from a wind tunnel and to establish modification that into a performance improvement. Five professional cyclists from the Kelme-Costa Blanca Team were studied in five positions, four on the aerobike and one on the standard bike. From our results we conclude that establishing small modifications in the aerohandlebars, which result in a more profitable position, can reduce RA. The use of aerohelmet was not shown to be always useful. It is necessary to take into account the technique employed, corrected RA values with the anthropometric characteristics, static vs dynamic assessment when comparing professional cyclists RA

Optimal reactive power dispatch by means of particle swarm optimization

RESUMEN: En este artículo se explora la optimización por enjambre de partículas (PSO) con algunas de sus variantes para dar solución al problema de flujo de potencia óptimo reactivo ORPD. Este problema consiste consiste en usar de forma óptima los recursos de potencia reactiva de un sistema de potencia, comúnmente con el objetivo de minimizar las pérdidas de energía y mejorar el perfil de tensiones. El ORPD es un problema no lineal y no convexo que involucra variables continuas y enteras y que presenta múltiples soluciones subóptimas. Además de la técnica PSO las variantes conocidas como Turbulent PSO (TPSO) y Turbulent Crazy PSO (TCPSO) fueron implementadas. Se realizaron varias pruebas en los sistemas IEEE de 57 y 118 barras comparando los resultados con otros reportados en la literatura técnica. Se encontró que el desempeño del PSO se mejora considerablemente cuando se aplican las variantes TPSO y TCPSO.ABSTRACT: In this paper the particle swarm optimization (PSO) along with some of its variants is explored to give solution to the optimal reactive power dispatch problem (ORPD). This problem consists of the optimal use of reactive power resources in a power system, usually with the aim of minimizing power loses and improving voltage profile. The ORPD is a non-lineal and non-convex problem that involves continues and discrete variables and features multiple sub-optimal solutions. Besides the PSO technique, the variants known as Turbulent PSO (TPSO) and Turbulent Crazy (PSO) were implemented. Several tests were performed on IEEE 57 and 118 bus test systems comparing results with other reported in the technical literature. It was found that the performance of PSO is considerably improved when the variants TPSO and TCPSO are applied