Demonstration of 10.7-Gb/s transmission in 50-km PON with uncooled free-running 1550-nm VCSEL

First-known demonstration of an uncooled, free-running 1550 nm VCSEL at 10.7 Gb/s over 50 km PON uplink with 35 km SMF and 15 km inverse dispersion fiber, achieving 24 dB margin for 10−9 BER

Evaluation of Morphological Properties of Solanum chrysotrichum Cell Cultures in a Shake Flask and Fermentor and Rheological Properties of Broths

Solanum chrysotrichum cells were grown in a shake flask and a stirred tank bioreactor. Their growth kinetics and rheological and morphological behaviors were evaluated. The specific growth rate obtained in both systems was similar (0.09 day–1), but biomass yield achieved in shake flasks was 60 % higher than that in the fermentor. Culture broths exhibited non-Newtonian and shear-thinning characteristics, which can be simulated by the Ostwald de Waele model (power law). Results show that the pseudoplasticity of culture broths was determined by the biomass concentration and aggregate size distribution, while the aggregate roundness, measured as the elliptical form factor, was similar in both systems.Morphological analysis indicated that 100 % of the cell aggregates from the fermentor were <0.25 mm2, and their size distribution remained constant during cultivation. The cultures grown in shake flasks presented a tendency to increase their aggregate size as a consequence of cell growth. The reduction of the size of S. chrysotrichum aggregates during the scale-up had an important influence on flow index behavior and consistency coefficient values

Momento Económico (40)

Temas de hoy, 2/ Hipótesis para la investigación sobre reconversión industrial, Ricardo Javier Martínez Atala, 3/ Reconversión automotriz y resistencia obrera en Volkswagen de México, Rogelio Palafox, Pedro Monroy y Yolanda Montiel, 6/ Estrategia del movimiento obrero ante la reconversión productiva, Socorro Fonseca Córdoba, 10/ Las operadoras del departamento de tráfico de Teléfonos de México ante la tecnología digital, Ma. Elena del Villar, 15

Antimicrobial activity of the fiber produced by “pochote” Ceiba aesculifolia subsp. parvifolia

Background: The cotton-like fiber from the fruit of Pochote (Ceiba aesculifolia subsp. parvifolia) can be applied to wounds for healing purposes. As microorganisms can infect wounds and hamper the wound healing process, the aim of this study was to determine the antimicrobial activity and chemical composition of the methanolic extract of Pochote fiber.Materials and Methods: The methanolic extract was tested against bacteria and fungi. For bacteria, the Kirby-Baüer disc diffusion and broth dilution methods were employed to determine the MIC and MBC. In addition, bactericidal kinetic curves were generated. The antifungal activity was determined by the radial diffusion method. The antioxidant activity, total phenolic content, and the flavonoid content were determined. Bioassay guided fractionation was also performed.Results: The methanolic extract showed activity against Enterococcus faecalis, Staphylococcus aureus and Vibrio cholerae (cc). The tested V. cholerae strains were the most sensitive strains, and exhibited a clear CFU size reduction from the bactericidal kinetic curves. The methanolic extract had activity against T. mentagrophytes and R. lilacina. The antioxidant activity (SC50= 36.42 μg/mL) was related to the total phenolic (74.4 mg eAG/g) and flavonoid content (21.982 mg (eQ)/g). The bioassay guided fractionation results suggested that the antimicrobial properties of the extract may act through synergism because the total extract had higher activity against bacteria compared to the collected fractions.Conclusion: This study scientifically validates the application of the fruit fiber from Pochote as a part of a traditional medicine approach to alleviate infections caused by bacteria and fungi.Keywords: antimicrobial, Ceiba, Bombacaceae, fruit fib

A novel method for combating dispersion induced power fading in dispersion compensating fiber

\u3cp\u3eWe experimentally investigate the performance of 60 GHz double sideband (DSB) radio over fiber (RoF) links that employ dispersion compensating fiber (DCF). Error free transmission of 3 Gbps signals over 1 m of wireless distance is reported. In order to overcome experimentally observed chromatic dispersion (CD) induced power fading of radio frequency (RF) signal, we propose a method for improvement of RF carrierto- noise (C/N) ratio through introduction of a degree of RF frequency tunability. Overall results improve important aspects of directly modulated RoF systems and demonstrate the feasibility of high carrier frequency and wide bandwidth RF signals delivery in RoF links including DCF fiber. Error free performance that we obtain for 3 Gbps amplitude shift-keying (ASK) signals enables uncompressed high-definition 1080p video delivery.\u3c/p\u3

Free-Running 1550 nm VCSEL for 10.7 Gb/s Transmission in 99.7 km PON

We present a cooler-less, free-running 1550 nm vertical cavity surface emitting laser (VCSEL) directly modulated at 10.7 Gb/s. We also report on error-free transmission through 40 km of standard single-mode optical fiber, achieved without the use of dispersion-mitigation or mid-span amplification. Inverse-dispersion fiber was utilized to realize a dispersion-matched 99.7 km optical access uplink supporting error-free transmission with 27 dB loss margin. These results indicate the feasibility of implementing cooler-less long-wavelength VCSEL devices in long-reach optical access networks

Conocimiento de los estudiantes respecto a los contenidos del programa de educación matemática, NB2 cuarto año básico.

Tesis (Profesor de Educación General Básica, Licenciado en Educación)RESUMEN: Estudio descriptivo de carácter transversal, orientado a diagnosticar el nivel de conocimiento obtenido por los estudiantes de dos establecimientos de distinta dependencia. Se obtendrá el nivel de logro por los estudiantes y se determinará la influencia de las variables sexo y dependencia sobre los resultados que se obtendrán en la aplicación del instrumento. Para la obtención de la información se contempló el uso de un instrumento internacional de tendencias en Matemáticas y Ciencias llamado TIMSS, dirigido a estudiantes de cuarto año básico con los contenidos vigentes en el curriculum nacional. Respecto a los resultados es posible concluir que influyen las variables sexo y dependencia pero no significativamente sobre los resultados obtenidos en la aplicación del instrumento.ABSTRACT: Abstract Transversal descriptive study, designed to diagnose the level of knowledge gained by students in two different establishments dependence. You will get the level of achievement by students and determine the influence of sex and dependent variables on the results obtained in applying the instrument. To obtain the information contemplated the use of an international trend in math and science called TIMSS aimed at seniors with the contents basic force in thenational curriculum. Regarding the results we can conclude that the variables of sex and influence but not significantly dependent on the results achieved in implementing the instrument

Chinese energy and climate policies after Durban: save the Kyoto Protocol

Nowadays, one of the urgent issues regarding global climate change is to discuss the future of the second period of the Kyoto Protocol. However, the divergence of views and opinions among parties in the last Conference of the Parties of the United Nations Framework Convention on Climate Change, held in Durban in December 2011, is still large. One of the bones of contention is whether the emerging developing countries, like China, should make commitments and legally bind themselves to a Green House Gas (GHG) reduction target in near future. As the largest GHG emitting country, China and its energy and climate policies will play an important role in global climate change and will also significantly influence the other countries? policies and the global climate negotiation. In this paper, we review the current differences among parties in the Durban Conference, and we analyze the recent situation, barriers, and future policies in China. Finally we highlight the impact and potential effect of Clean Development Mechanisms in avoiding China?s barriers regarding climate change. Results show that China is making a great effort to mitigate climate change by establishing and reforming its energy and climate policies in order to achieve a low-carbon development. At the same time, more innovation and international collaboration is needed in China to achieve this goal