Desarrollo y aplicación de una estrategia de biofertilización en plantas de arroz (oryza sativa l.) Empleando microorganismos promotores de crecimiento vegetal

El arroz (Oryza sativa L.) es uno de los cereales más importantes del planeta. Su cultivo demanda grandes cantidades de nutrientes, particularmente nitrógeno y fosforo. Sin embargo, la baja disponibilidad de estos nutrientes en el suelo ha llevado al uso de fertilizantes químicos, generando incrementos en los costos de producción y daños ambientales. El suelo alberga una gran diversidad microbiana que facilita la captación de estos nutrientes por parte de la planta gracias a mecanismos como la solublización y mineralización de fósforo, producción de hormonas reguladoras del crecimiento y fijación de nitrógeno. La mayoría de estos microorganismos hacen parte de las Rizobacterias Promotoras de Crecimiento Vegetal (RPCV), destacándose los Bacilos Aerobios Formadores de Endospora (BAFEs), que colonizan la rizosfera de las plantas, estimulando su crecimiento, incrementando su longitud y biomasa. Se evaluó, en un screening inicial, la actividad promotora de crecimiento vegetal de 56 aislamientos obtenidos de la rizosfera de diferentes especies vegetales, preparando suspensiones ajustadas a una concentración de 5x107 UFC.mL-1 para la inoculación de semillas de arroz pregerminadas. Una vez inoculadas, las semillas fueron sembradas y crecidas durante 30 días en un sustrato inerte, y fertilizadas con roca fosfórica y solución nutritiva de Hoagland 20%. Los mejores 17 tratamientos fueron repetidos en el tiempo obteniendo 5 aislamientos sobresalientes incrementando hasta en un 31 y 56% la longitud y 45 y 169% el peso seco de vástago y raíz respectivamente, con respecto al tratamiento control; adicionalmente presentaron actividad solubilizadora de fosfato de calcio, actividad mineralizadora de fitato in vitro, así como también liberación de fosfatos a partir de residuo vegetal. Con base en los criterios anteriores, tres de los aislamientos fueron seleccionados para evaluar su efecto promotor en plántulas de arroz sembradas en un suelo enmendado con tamo de arroz previamente biodegradado usando una dosis de fertilización nitrogenada, en condiciones de invernadero. Los resultados mostraron que las cepas seleccionadas incrementaron significativamente las variables evaluadas, proporcionando una buena estrategia para favorecer el desarrollo del cultivo del arroz.Abstract: Rice (Oriza sativa) is one of the most important cereals worldwide. Its cultivation requires large amounts of nutrients, particularly nitrogen and phosphorus. However, the low efficiency in the assimilation of these nutrients has led to overuse of chemical fertilizers, generating increases in production costs and environmental damage. Plant Growth Promoting Rhizobacteria (PGPR), especially the aerobic endospore forming bacteria (AEFBs), are able to colonize the rhizosphere of rice plants, stimulating its growth. In the present study, we evaluated the plant growth promotion activity of 56 isolates, obtained from the rhizosphere of different plant´s species and previously characterized as a function of attributes of growth promotion (solubilization of tricalcium phosphate and mineralization of phosphate). The evaluation of the plant growth promotion capacity of the isolates was carried out using bacterial suspensions on pre-germinated rice seedlings, previously adjusted to a concentration of 5x107 CFU.mL-1. Once inoculated, the seeds were sown and grown for 30 days in an inert substrate, and fertilized with phosphate rock and Hoagland nutrient solution at 20%. Seventeen best treatments were repeated over time, allowing to confirm the activity of five isolates which increased between 56% and 31% and 45% and 168% the length and dry weight of root and stem, respectively, compared to the control treatment. Based on the mentioned results, three isolates were selected to evaluate their effect as plant growth promoter on rice seedlings, planted in amended soil with bio-composted rice straw and treated with a doses of nitrogen fertilization, under greenhouse conditions. The treatments increased the development of stem and root of the seedlings, alone or in combination with straw degrading, providing a good strategy to encourage the development of rice cultivation.Maestrí

Composición y producción de 8 temas de música electrónica a partir de sonidos concretos, técnicas de manipulación y síntesis sonora

Maestro (a) en MúsicaPregrad

Incidence of the harvesting age on postharvest characteristics behavior of dominico hartón plantain (musa aab simmonds)

In this study a physical, chemical and physiological characterization of Dominico Hartón plantain grown in the Belalcázar municipality (Department of Caldas, Colombia) during harvest and postharvest was carried out. The research was performed with fruits of 14, 16 and 18 weeks after flowering. Every two days until senescence changes in weight, firmness, parameters of color L*a*b*, pulp/peel ratio, maturity index, pH, humidity, starch, respiration rate and ethylene rate were measured. This study used a longitudinal repeated measures design, balanced, with a three-level factor. The factor evaluated was harvesting time and the response variables were the physicochemical parameters. The results showed variation in weight near to 7%, the tint color parameter was between -61.46 and 86.74, chroma between 26.31 and 37.11 and ΔE of 1.4603 to 8360, the pH ranged from 6.2 to 3.98, pulp/peel of 2.53 to 4.11, the relationship °Brix/acidity of 11.36 to 26.2, humidity content between 60.56% and 56%, starch between 51.7% and 67% DM, the CO2 production rate between 3.4 and 8.9 g/kg.h, ethylene from 24 to 225 μL/kg.h. The maturation parameters showed climacteric behavior and total days to ripening were 9, 14 and 21 for the fruits of 18, 16 and 14 weeks from flowering.En el departamento de Caldas, Colombia, se realizó la caracterización física, química y fisiológica durante las fases de cosecha y poscosecha del plátano Dominico Hartón (Musa AAB Simmonds) cultivado en el municipio de Belalcázar. La investigación se hizo con frutos de 14, 16 y 18 semanas después de la floración. Cada 2 días y hasta senescencia se evaluaron los cambios de peso, firmeza, parámetros de color L*a*b*, relación pulpa/cáscara, índice de madurez, pH, humedad, almidones, índice de respiración y tasa de etileno. En este trabajo se utilizó un diseño longitudinal de medidas repetidas, balanceado, con un factor en tres niveles. El factor evaluado fue el tiempo de cosecha y las variables de respuesta fueron los parámetros fisicoquímicos. Los resultados mostraron variación en peso cercanas a 7%, el parámetro de color tinte varió entre -61.46 y 86.74, el croma entre 26.31 y 37.11 y el ΔE entre 1.4603 y 8.360, el pH varió entre 6.2 y 3.98, una relación pulpa/cáscara entre 2.53 y 4.11, la relación °brix/ acidez entre 11.36 y 26.2, la humedad entre 60.56% y 56%, el almidón entre 51.7% y 67% de MS, la tasa de producción de CO2 entre 3.4 y 8.9 g/kg por hora, el etileno entre 24 y 225 μlt/kg por hora. Los parámetros de maduración mostraron comportamiento climatérico y los días a maduración total fueron de 9, 14 y 21 para los frutos de 18, 16 y 14 semanas desde floración

Reporte de caso de necrosis apical en un cultivo de mango (Mangifera indica L.) establecido bajo condiciones del Caribe seco colombiano

Bacterial apical necrosis of mango (Mangifera indica L.) is an acute disease reported mainly in Southern Europe, characterized by the generation of necrotic lesions in buds and leaves that spread through the petioles towards the stems. Its incidence results in significant economic losses due to a decrease in production. Known causative agents of this disease are the bacteria Pseudomonas syringae and Pantoea spp., which survive as epiphytes on plant surfaces. In a two-year-old mango cv. Keitt orchard, established at the Colombian Corporation for Agricultural Research (AGROSAVIA), Motilonia Research Station, mango trees exhibited symptoms of necrosis in buds, leaves, and branches. The mango plants were affected downwards, causing their death 30 days after the first symptoms. Five samples of affected leaf tissue and petioles were taken to isolate the causative agent and make a diagnosis to manage the disease properly. The samples were superficially disinfected and incubated in a humid chamber and culture media for three days. After incubation, hyphae, exudates, and bacterial colonies were plated on solid culture media. The isolates obtained were characterized morphologically and biochemically. The results showed the presence of bacteria identified as Pantoea spp. by amplifying and sequencing the region coding for the 16S subunit of rRNA. In vitro pathogenicity tests preliminarily suggest Pantoea spp. as the causative agent of the disease. This work is the first report of apical necrosis by Pantoea spp. in mango for Colombia.La necrosis apical bacteriana del mango es una enfermedad crítica reportada principalmente en Europa, que se caracteriza por la generación de lesiones necróticas en yemas y hojas, las cuales se extienden a través de los peciolos hacia los tallos. Su incidencia resulta en pérdidas económicas importantes debido a una disminución de la producción. Los agentes causales conocidos de esta enfermedad son las bacterias Pseudomonas syringae y Pantoea spp., que sobreviven como epífitas en la superficie de las plantas.  En un cultivo de mango cv. Keitt de dos años, establecido en la Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA), Centro de Investigación Motilonia, se evidenciaron síntomas de necrosis en yemas, hojas y ramas.  Las plantas de mango se vieron afectadas de forma descendente hasta su muerte a los 30 días después los primeros síntomas. Se tomaron cinco muestras de tejido foliar afectado y pecíolos para aislar el agente causal y generar un diagnóstico a fin de realizar un manejo preciso de la enfermedad. Las muestras se desinfectaron superficialmente y se incubaron en cámara húmeda y medios de cultivo por tres días. Después de la incubación, las hifas, los exudados y las colonias bacterianas se sembraron en medios de cultivo sólidos. Los aislamientos obtenidos se caracterizaron a nivel morfológico y bioquímico. Los resultados arrojaron la presencia de bacterias identificadas como Pantoea spp. por amplificación y secuenciación de la región que codifica para la subunidad 16S del ARNr. Las pruebas de patogenicidad in vitro sugieren preliminarmente a Pantoea spp. como el agente causal de la enfermedad. Este trabajo es el primer reporte de necrosis apical por Pantoea spp. en mango para Colombia

Reviewing the connection between speech and obstructive sleep apnea

The electronic version of this article is the complete one and can be found online at: http://link.springer.com/article/10.1186/s12938-016-0138-5Background: Sleep apnea (OSA) is a common sleep disorder characterized by recurring breathing pauses during sleep caused by a blockage of the upper airway (UA). The altered UA structure or function in OSA speakers has led to hypothesize the automatic analysis of speech for OSA assessment. In this paper we critically review several approaches using speech analysis and machine learning techniques for OSA detection, and discuss the limitations that can arise when using machine learning techniques for diagnostic applications. Methods: A large speech database including 426 male Spanish speakers suspected to suffer OSA and derived to a sleep disorders unit was used to study the clinical validity of several proposals using machine learning techniques to predict the apnea–hypopnea index (AHI) or classify individuals according to their OSA severity. AHI describes the severity of patients’ condition. We first evaluate AHI prediction using state-of-theart speaker recognition technologies: speech spectral information is modelled using supervectors or i-vectors techniques, and AHI is predicted through support vector regression (SVR). Using the same database we then critically review several OSA classification approaches previously proposed. The influence and possible interference of other clinical variables or characteristics available for our OSA population: age, height, weight, body mass index, and cervical perimeter, are also studied. Results: The poor results obtained when estimating AHI using supervectors or i-vectors followed by SVR contrast with the positive results reported by previous research. This fact prompted us to a careful review of these approaches, also testing some reported results over our database. Several methodological limitations and deficiencies were detected that may have led to overoptimistic results. Conclusion: The methodological deficiencies observed after critically reviewing previous research can be relevant examples of potential pitfalls when using machine learning techniques for diagnostic applications. We have found two common limitations that can explain the likelihood of false discovery in previous research: (1) the use of prediction models derived from sources, such as speech, which are also correlated with other patient characteristics (age, height, sex,…) that act as confounding factors; and (2) overfitting of feature selection and validation methods when working with a high number of variables compared to the number of cases. We hope this study could not only be a useful example of relevant issues when using machine learning for medical diagnosis, but it will also help in guiding further research on the connection between speech and OSA.Authors thank to Sonia Martinez Diaz for her effort in collecting the OSA database that is used in this study. This research was partly supported by the Ministry of Economy and Competitiveness of Spain and the European Union (FEDER) under project "CMC-V2", TEC2012-37585-C02

Speech Signal and Facial Image Processing for Obstructive Sleep Apnea Assessment

Obstructive sleep apnea (OSA) is a common sleep disorder characterized by recurring breathing pauses during sleep caused by a blockage of the upper airway (UA). OSA is generally diagnosed through a costly procedure requiring an overnight stay of the patient at the hospital. This has led to proposing less costly procedures based on the analysis of patients' facial images and voice recordings to help in OSA detection and severity assessment. In this paper we investigate the use of both image and speech processing to estimate the apnea-hypopnea index, AHI (which describes the severity of the condition), over a population of 285 male Spanish subjects suspected to suffer from OSA and referred to a Sleep Disorders Unit. Photographs and voice recordings were collected in a supervised but not highly controlled way trying to test a scenario close to an OSA assessment application running on a mobile device (i.e., smartphones or tablets). Spectral information in speech utterances is modeled by a state-of-the-art low-dimensional acoustic representation, called i-vector. A set of local craniofacial features related to OSA are extracted from images after detecting facial landmarks using Active Appearance Models (AAMs). Support vector regression (SVR) is applied on facial features and i-vectors to estimate the AHI.The activities in this paper were funded by the Spanish Ministry of Economy and Competitiveness and the European Union (FEDER) as part of the TEC2012-37585-C02 (CMC-V2) project. Authors also thank Sonia Martinez Diaz for her effort in collecting the OSA database that is used in this study

Carbon nanofiber-based palladium/zinc catalysts for the hydrogenation of carbon dioxide to methanol at atmospheric pressure

Palladium/zinc catalysts supported on carbon nanofibers (CNFs) have been used to study the catalytic performance in the hydrogenation of CO2 to obtain methanol at atmospheric pressure. The carbon nanofiber support has an influence on the nature of the PdZn alloy formed. The effect of the Pd/Zn molar ratio on the PdZn alloy particle size was analyzed. Lower Pd/Zn molar ratio leads to higher PdZn alloy particle size, which was associated with higher selectivity toward methanol. The influence of the type of nanofiber (platelet or fishbone) on the catalytic behavior was also studied and compared with that of a conventional Pd/ZnO catalyst. The palladium/zinc catalyst supported on platelet nanofiber was considered to be a good candidate for the hydrogenation of carbon dioxide to methanol.Se han utilizado catalizadores de paladio/zinc soportados sobre nanofibras de carbono (CNFs) para estudiar el rendimiento catalítico en la hidrogenación de CO 2 para obtener metanol a presión atmosférica. El soporte de nanofibras de carbono influye en la naturaleza de la aleación de PdZn formada. Se analizó el efecto de la relación molar Pd/Zn sobre el tamaño de partícula de la aleación de PdZn. Una relación molar más baja de Pd/Zn conduce a un tamaño de partícula de aleación de PdZn más alto, lo que se asoció con una mayor selectividad hacia el metanol. También se estudió la influencia del tipo de nanofibra (plaqueta o espina de pescado) en el comportamiento catalítico y se comparó con el de un catalizador convencional de Pd/ZnO. El catalizador de paladio/zinc soportado sobre nanofibras de plaquetas se consideró un buen candidato para la hidrogenación de dióxido de carbono a metanol

Manejo de las mieles generadas en la tecnología becolsub para eliminar el impacto ambiental ocasionado por los lixiviados de café.

En CENICAFE se evaluó una alternativa para eliminar el impacto ambiental generado por los lixiviados producidos por el beneficio del café denominada BECOLSUB, la cual consistió de dos etapas: en la primera, se mezclan con la pulpa el 61.23% de los fluidos resultantes del proceso de desmucilaginado mecánico (básicamente mucilago, agua adicionada e impurezas) y en la segunda se retiran manualmente los insolubles presentes en el flujo no mezclado con la pulpa y se aumenta la concentración de sólidos, utilizando un evaporador rustico operado con energía térmica proveniente de una estufa campesina. Con el evaporador en las condiciones de trabajo de la estufa (15 h/d) se logra controlar el 100% de la contaminación generada por los lixiviados en una finca con producción anual de 240 de café pergamino se por año (cps/año) (15.000 kg de café cereza (cc)) que utilice la tecnología BECOLSUB. La eficiencia térmica del evaporados y del sistema global fueron 57.01% y 20.74% respectivamente. El fluido concentrado presento 295.000 ppm de DQO y 164254 ppm de solidos totales (ST) y 35% de grados brix