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Emisión de N2O con fertilización nitrogenada en fertirriego y fertilización convencional
Sandra Grisell Mora Ravelo,Manuel Sandoval Villa,Francisco Gavi Reyes,Prometeo Sánchez García
Revista internacional de contaminación ambiental , 2005,
Abstract: El relacionar el uso de fertilizantes químicos u orgánicos nitrogenados con la contaminación ambiental, implica adoptar alternativas que reduzcan las pérdidas de nitrógeno (N) del suelo que podría ser utilizado por los cultivos. La fertirrigación es una técnica de aplicación de agua y fertilizante que mejora la eficiencia en el uso de los fertilizantes mediante el riego por goteo. No existen reportes sobre como la fertirrigación afecta a la desnitrificación. El objetivo del presente trabajo es estudiar cómo afectan la fertirrigación y la fertilización convencional a la desnitrificación y verificar si, efectivamente, es posible reducir las emisiones de óxido nitroso (N 2 O) hacia la atmósfera. Se utilizó la captura de N 2 O in situpor el método adaptado por Grageda (1999) y Vivanco (2000). Las muestras de N 2 O se tomaron a las 2, 24, 48 y 72 h después del riego. La temperatura del suelo se midió con un termómetro aproximadamente a 10 cm de profundidad del suelo. La humedad del suelo (0 12 cm) se determinó con la ayuda de un instrumento DT DeltaT devices, tipo ML2 ThetaProbe. La cuantificación de N 2 O fue por cromatografía de gases. Los cálculos y análisis estadístico se efectuaron con el paquete estadístico SAS (SAS 1998). Los resultados obtenidos para la emisión de N 2 O manifiestan que el factor que más influyó en el sistema de riego convencional fue la humedad ya que existió una diferencia significativa a las 2, 24 y 48 h después del riego con respecto al fertirriego (riego por goteo). A pesar de que estadísticamente no hubo diferencia significativa en la emisión de N 2 O entre sistemas se obtuvo una concentración en riego por goteo de 0.69 y 2.82 mM menor que en el sistema convencional a las 48 y 72 h. Las temperaturas registradas a lo largo del desarrollo del cultivo estuvieron por debajo de las reportadas, por lo que se asume que este factor influyó en la disminución de la producción de N 2 O. Con respecto al pH del suelo se trabajó en un rango de 8.0 a 8.4, promedio superior al reportado como pH óptimo para el crecimiento de brócoli por lo que probablemente también influyó en la emisión de N 2 O en el sistema convencional y en el fertirriego.
Dinamic of Bacteria Desnitrificants and Nitrificants in the Rizospheric of Wheat with Slow Release of Fertilizer, Irrigated with Waste or Well Water  [PDF]
Sandra Grisell Mora-Ravelo, Francisco Gavi Reyes, Jesús Pérez Moreno, Juan José Pe?a Cabriales, Leonardo Tijerina Chávez, Ma. de Lourdes de la Isla de Bauer
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.34048
Abstract:

The study of the paper about the rhizosphere in the transformation of nitrogen compounds can generate knowledge of the microbial and biochemical atmosphere of the rhizosphere of wheat, for the understanding of the dynamics of the N in agricultural zones, with the purpose of optimizing the fertilizer use and increasing the productivity of the cultures. Therefore, the objective of the present work was to know the effect the rhizosphere in the dynamics of the bacterial populations that take part in the cycle of the N in wheat nourished with slow release fertilizer and one commercial, irrigated with waste water or well. Analyses in the soil took place vertisol used in the experiment with the rhizospheric and non rhizospheric fraction. The slow release fertilizer used has a matrix enriched with N and P and is in the process of being patented (it explains in materials and methods). Each fertilizer was evaluated and the combination of the slow release fertilizer with organic fertilizer. The technique of the number most probable was used (MNP) to carry out the quantification of the nitrificants and denitrificants bacteria to the 55, 67 and 97 days after sowing (Dds). The results obtained for the MNP of denitrificants bacteria and Nitrosomonas indicate that the effect average of the types of water, soil and fertilizers, as well as their interaction to each other was not significant (p > 0.05). The effect of the fertilizing type and soil (rhizospheric and non rhizospheric) in the MNP of Nitrobacter was significant (p < 0.05). The tendencies show that the non rhizospheric soil is more favorable for the development of denitrificants bacteria and Nitrobacter, whereas the MNP of Nitrosomonas was greater in rhizospheric soil.

NMO in pediatric patients: brain involvement and clinical expression
Pe?a, Joaquín A.;Ravelo, María Elena;Mora-La Cruz, Eduardo;Montiel-Nava, Cecilia;
Arquivos de Neuro-Psiquiatria , 2011, DOI: 10.1590/S0004-282X2011000100008
Abstract: objective: to analyze the clinical, neuroimaging characteristics and positivity of the acquaporin water channel (nmo-igg) in pediatric patients with neuromyelitis optica (nmo). this disorder could have a variable clinical expression. to address such variability, the term nmo spectrum has been suggested. method: we evaluated six pediatric patients, with a median age of 11 years at the time of the study, with the diagnosis of nmo by the wingerchuck criteria. results: all the cases exhibited bilateral optic neuritis (on). four patients had abnormalities on brain mri from the onset,although only three of them developed symptoms correlated to those lesions during the course of their disorder. nmo-igg was positive in 80%. conclusion: optic neuropathy is the most impaired feature in nmo patients. brain mri lesions are not compatible with multiple sclerosis and positivity of the nmo-igg are also present in nmo pediatric patients, confirming the heterogeneity in the expression of this disorder.
Desnitrificación de un fertilizante de lenta liberación y urea+fosfato monoamónico aplicados a trigo irrigado con agua residual o de pozo
Sandra Grisell Mora Ravelo,Francisco Gavi Reyes,Juan José Pe?a Cabriales,Jesús Peréz Moreno
Revista internacional de contaminación ambiental , 2007,
Abstract: El estudio de la emisión de óxido nitroso (N2O) producto de la combinación de tipos de fertilizante y agua en suelo rizosférico, y no rizosférico a lo largo del ciclo del cultivo, puede generar conocimiento que contribuya a incrementar la eficiencia de recuperación del N de los fertilizantes o abonos y a reducir las pérdidas de nitrógeno (N) por desnitrificación. El empleo eficiente de fertilizantes nitrogenados y de aguas residuales no tratadas de origen urbano por los cultivos es una necesidad agronómica, económica y ambiental. La desnitrificación es un factor importante que generalmente disminuye la eficiencia del N aplicado a los cultivos. El objetivo del presente trabajo fue evaluar la desnitrificación de un fertilizante de lenta liberación usando como referencia urea+fosfato monoamónico y fertilizante orgánico, en trigo irrigado con agua residual o de pozo. Se efectuaron análisis en el suelo vertisol empleado en el experimento con la fracción rizosférica y no rizosférica. El fertilizante de lenta liberación usado tiene una matriz enriquecida con N y fósforo (P) y se encuentra en proceso de ser patentado. Se evaluó cada fertilizante y la combinación del fertilizante de lenta liberación con fertilizante orgánico. Las muestras de suelo rizosférico y no rizosférico fueron colectadas a los 55, 67 y 97 días después de la siembra, se incubaron durante 18 días a una temperatura de 25 °C controlando diariamente la humedad. Los resultados (p < 0.05) arrojaron que las interacciones entre: muestreos y tipos de agua, muestreos y fertilizantes y tipos de agua y fertilizantes afectaron (p < 0.06) la emisión de N2O, la cual se incrementó al aplicar urea+fosfato monoamónico junto con agua residual. En promedio existió menos emisión de N2O al aplicar fertilizante de lenta liberación o fertilizante orgánico al irrigar con agua de pozo que con agua residual. El uso de agua residual en promedio se asoció con una mayor pérdida de N. La mayor emisión promedio de N2O ocurrió a los 67 días después de la siembra. La desnitrificación promedio fue similar en el suelo rizosférico y no rizosférico.
Investigation on the Microwave Pulse Signal Compression with Ngd Circuit
Blaise Ravelo
PIER C , 2011, DOI: 10.2528/PIERC10122305
Abstract: This paper demonstrates the exhibition of pulse compression from an electronic circuit with negative group delay (NGD). This circuit consists of a field effect transistor (FET) cascaded with shunt RLC network. Theoretic and experimental investigations have proved that, at its resonance frequency, the group delay of this circuit is always negative. The present study shows that around this resonance, it presents a gain form enabling to generate pulse compression. To validate this concept, as proof-of-principle, devices with one- and two-stages FET were implemented and tested. Measurements of the one-stage test device evidenced an NGD of about -2.5 ns and simultaneously with 2 dB amplification operating at 622 MHz resonance frequency. In the frequency domain, in the case of a Gaussian input pulse with 40\,MHz frequency standard deviation, this resulted in 125% expansion of pulse width compared to the input one. In time domain, simulations showed that the compression was about 80% in the case of an input Gaussian pulse with 4 ns standard deviation. With the other prototype comprised of two-stage NGD cell, the use of a sine carrier of about 1.03 GHz allowed to achieve 87% pulse width compression.
Behavioral Model of Symmetrical Multi-Level T-Tree Interconnects
Blaise Ravelo
PIER B , 2012, DOI: 10.2528/PIERB12040205
Abstract: An accurate and behavioral modeling method of symmetrical T-tree interconnect network is successfully investigated in this paper. The T-tree network topology understudy is consisted of elementary lumped L-cells formed by series impedance and parallel admittance. It is demonstrated how the input-output signal paths of this single input multiple output (SIMO) tree network can be reduced to single input single output (SISO) network composed of L-cells in cascade. The literal expressions of the currents, the input impedances and the voltage transfer function of the T-tree electrical interconnect via elementary transfer matrix products are determined. Thus, the exact expression of the multi-level behavioral T-tree transfer function is established. The routine algorithm developed was implemented in Matlab programs. As application of the developed modeling method, the analysis of T-tree topology comprised of different and identical RLC-cells is conducted. To demonstrate the relevance of the model established, lumped RLC T-tree networks with different levels for the microelectronic interconnect application are designed and simulated. The work flow illustrating the guideline for the application of the routine algorithm summarizing the modeling method is proposed. Then, 3D-microstrip T-tree interconnects with width 0.1 μm and length 3 mm printed on FR4-substrate were considered. As results, very good agreement between the results from the reduced behavioral model proposed and SPICE-computations is found both in frequency- and time-domains by considering arbitrary binary sequence ''01001100" with 2 Gsym/s rate. The model proposed in this paper presents significant benefits in terms of flexibility and very less computation times. It can be used during the design process of the PCB and the microelectronic circuits for the signal integrity prediction. In the continuation of this work, the modeling of clock T-tree interconnects for packaging systems composed of distributed elements using an analogue process is in progress.
E-Field Extraction from H-Near-Field in Time-Domain by Using Pws Method
Blaise Ravelo
PIER B , 2010, DOI: 10.2528/PIERB10071307
Abstract: A novel technique of the electric- or E- field extraction from the magnetic- or H- near-field in timedomain is reported. This technique is based on the use of the Maxwell-Ampere relation associated to the plane wave spectrum (PWS) transform. It is useful for the E-near-field computations and measurements which are practically complicated in time-domain in particular, for the EMC applications. The considered EM-field radiation is generated by a set of electric dipoles excited by an ultra-short duration current having frequency bandwidth of about 10-GHz. The presented EM-field calculation technique is carried out by taking into account the evanescent wave effects. In the first step, the time-dependent H-field data mapped in 2-D plan placed at the height above the radiating devices are transposed in frequency-dependent data through the fast Fourier transform. In order to respect the near-field approach, the arbitrary distance between the EM-field mapping plan and radiating source plan should be below one-sixth of the excitation signal minimal wavelength. In the second step, one applies the PWS transform to the obtained frequency-data. Then, through the Maxwell-Ampere relation, one can extract the E-field from the calculated PWS of the H-field. In the last step, the inverse fast Fourier transform of the obtained E-field gives the expected time-dependent results. The relevance of the proposed technique was confirmed by considering a set of five dipole sources placed arbitrarily in the horizontal plan equated by z = 0 and excited by a pulse current having amplitude of 50 mA and half-width of about 0.6 ns. As expected, by using the , and 2-D data calculated with Matlab in the rectangular plan placed at = 3 mm and = 5 mm above the radiating source, it was demonstrated that with the proposed technique, one can determine the three components of the E-field , and .
Ambivalencia y contradicción: reproducción del proceso de alcoholización en los ni os
Patricia Ravelo
Nueva antropología , 1988,
Abstract:
Esclerosis Múltiple en ni?os: clarificando su ubicación dentro del espectro desmielinizante
Pe?a,Joaquín Antonio; Montiel-Nava,Cecilia; Ravelo,María Elena; González,Solmary; Mora La-Cruz,Eduardo;
Investigación Clínica , 2006,
Abstract: multiple sclerosis (ms) is an autoimmune disease caused by the destruction of the myelin layer and the nervous fibers, and secondary by a progressive neuronal damage. it is characterized by episodes of demyelination disseminated in time and space in different areas of the white matter of the cns which includes periventricular region, spinal cord, brain stem, cerebellum and optical nerve. due to the confusing differential diagnosis of ms in children with other demyelinating diseases such as adem, it is important to reach this diagnosis when there is proof of white matter lesions disseminated in time and space that cannot be explained by any other mechanisms or pathologies. the goal of this paper is to review the diagnostic parameters used for ms in the pediatric age, the dilemmas regarding the validity of diagnostic criteria, clinical manifestations, differentiation of other demyelinating diseases, and the diagnostic process. ms although infrequent, is a valid diagnosis among the spectrum of childhood inflammatory demyelinating diseases. the clinical presentation might be indistinguishable from a multifocal acute disseminated encephalopathy or could be presented with just focal signs. a reasonable clinical judgment and the practice of laboratory tests confirm or rule out the diagnosis. it is not possible to differentiate between adem and ms in a first episode, nor by the clinical, the csf, neither the neuroimaging. there are still needed consensus criteria both clinical and laboratory test. there are many question still to be answered using prospective studies, and standardized clinical measures that will allow the delimitation of the demographic, neurological, and neuropsychological aspects of the ms and other form of acquired demyelinating diseases in children.
Desnitrificación de un fertilizante de lenta liberación y urea+fosfato monoamónico aplicados a trigo irrigado con agua residual o de pozo
MORA RAVELO, Sandra Grisell;GAVI REYES, Francisco;PE?A CABRIALES, Juan José;PERéZ MORENO, Jesús;TIJERINA CHáVEZ, Leonardo;VAQUERA HUERTA, Humberto;
Revista internacional de contaminación ambiental , 2007,
Abstract: the study of n2o emission originated by the combination of different types of fertilizers and water on rizospheric soil, and non- rizospheric soil along the crop cycle, can contribute to useful knowledge in order to increase fertilizer and manure n recovery efficiency and to reduce the n loss by denitrification. the efficient use of nitrogen fertilizers and non- treated urban waste water for crops is an agronomic, economic and environmental need. the denitrification is an important factor that diminishes the n efficiency in crops. the objective of this investigation was to evaluate the denitrification of a slow release fertilizer using as reference urea plus monoamonium phosphate and an organic fertilizer, applied to wheat irrigated with urban waste water or well water. analyses were made in the vertisol type soil used in the experiment with both, rizospheric and non-rizospheric soil. the slow release fertilizer used has a matrix enriched with n and p and its patent is currently in progress. each fertilizer was evaluated alone, as well as the slow release fertilizer plus organic fertilizer. the samples of rhizospheric and non-rhizospheric soils for each treatment were collected at 55, 67 and 97 days after sowing and incubated during 18 days at 25 °c, controlling the soil humidity daily. the results (p < 0.05) showed that the interactions between samplings and types of water, samplings and fertilizers, and types of water and fertilizers affected (p < 0.06) the emission of n2o, which was increased when urea plus monoamonium phosphate and waste water were applied. on average, there was less n2o when emissions slow release fertilizer or organic fertilizer were applied and irrigated with well water as compared to irrigation with waste water. as well, use of waste water was, on average, associated with a bigger loss of n. the highest average emission in n2o was observed 67 days after sowing. the average denitrification was similar in the rhizospheric and non-rhizospheric
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