Cytochrome c 6-like protein as a putative donor of electrons to photosystem I in the cyanobacterium Nostoc sp. PCC 7119

Most organisms performing oxygenic photosynthesis contain either cytochrome c 6 or plastocyanin, or both, to transfer electrons from cytochrome b 6-f to photosystem I. Even though plastocyanin has superseded cytochrome c 6 along evolution, plants contain a modified cytochrome c 6, the so called cytochrome c 6A, whose function still remains unknown. In this article, we describe a second cytochrome c 6 (the so called cytochrome c 6-like protein), which is found in some cyanobacteria but is phylogenetically more related to plant cytochrome c 6A than to cyanobacterial cytochrome c 6. In this article, we conclude that the cytochrome c 6-like protein is a putative electron donor to photosystem I, but does play a role different to that of cytochrome c 6 and plastocyanin as it cannot accept electrons from cytochrome f. The existence of this third electron donor to PSI could explain why some cyanobacteria are able to grow photoautotrophically in the absence of both cytochrome c 6 and plastocyanin. In any way, the Cyt c 6-like protein from Nostoc sp. PCC 7119 would be potentially utilized for the biohydrogen production, using cell-free photosystem I catalytic nanoparticles.Dirección General de Investigación Científica y Técnica BFU2006-01361/BMCJunta de Andalucía PAI BIO022 BIO19

Unraveling the drift behaviour of the remarkable pulsar PSR B0826-34

We present new results from high sensitivity GMRT observations of PSR B0826-34. We provide a model to explain the observed subpulse drift properties of this pulsar, including the apparent reversals of the drift direction. In this model, PSR B0826-34 is close to being an aligned rotator. We solve for the emission geometry of this pulsar and show that the angle between the rotation and the magnetic axes is less than 5 deg. We see evidence for as many as 6 to 7 drifting bands in the main pulse at 318 MHz, which are part of a circulating system of about 15 spark-associated subpulse emission beams. We provide quantitative treatments of the aliasing problem and various effects of geometry. The observed drift rate is an aliased version of the true drift rate, such that a subpulse drifts to the location of the adjacent subpulse (or a multiple thereof) in about one pulsar period. We show that small variations, of the order of 3-8%, in the mean drift rate are then enough to explain the apparent reversals of drift direction. We find the mean circulation time of the drift pattern to be significantly longer than the predictions of the original RS75 model and propose an explanation for this, based on modified models with temperature regulated partial ion flow in the polar vacuum gap. From the variation of the mean subpulse separation across the main pulse window, we show that the spark pattern is not centred around the dipole axis, but around a point much closer (within a degree or so) to the rotation axis -- we discuss the implication of this.Comment: 23 pages (including 9 figure). Submitted to Astronomy and Astrophysics on November 11, 200

Evaluación de la sensibilidad de la escorrentía como función de los cambios en la temperatura y la precipitación sobre la cuenca del Río Magdalena

Debido a que la relación entre la escorrentía y la variabilidad climática es muy compleja, y dichasincertidumbres son aún mayores en el marco del cambio climático, este estudio pretende dar una idea del comportamiento del recurso hídrico al interior de la cuenca del río Magdalena ante los posibles cambios de variables climáticas como la precipitación y la temperatura. El análisis se centra en el establecimiento de una relación escorrentía-precipitación-temperatura empleando la Base de Datos de Precipitación y Temperatura del Aire de la Universidad de Delaware (University of Delaware Air Temperature y Precipitation, UD-ATP) y datos de medición de caudal en estaciones sobre el río. Se incluye además el cálculo de la elasticidad climática1 propuesta por Fu et al. (2007), y la estimación del caudal del río ante una de las proyecciones de cambio climático del IPCC-AR4 (Intergovernmental Panel on Climate Change 4th Assessment Report) evaluada por 13 modelos de circulación global en el escenario A1B.Because the relationship between streamflow and climate variability is very complex, and the uncertainties are even greater in a climate change context, estimating relationships between the climatic conditions and the Magdalena river streamflow will give an idea about river behavior against the potential changes of climatic variables, particularly changes of both precipitation and temperature. The analysis is focused on the establishment of a streamflowprecipitation- temperature relationship using the Database University of Delaware Air Temperature y Precipitation (UD-ATP) and streamflow stations on the river. The study includes the calculation of the climate elasticity defined by Fu et al. (2007), and the estimation of the river streamflow against one of the projections of climate change by IPCC-AR4 (Intergovernmental Panel on Climate Change 4th Assessment Report) evaluated by 13 global circulation models in the A1B scenario.Ingeniero (a) CivilPregrad

Mechanical properties and sustainability aspects of coconut fiber modified concrete: Propiedades mecánicas y aspectos de sostenibilidad de concreto modificado con fibras de coco

Coir fiber has been examined for their suitability as reinforcement of concrete. Mechanical properties and sustainability aspects of concrete composites were estimated after 7. 14, and 28 days of curing. Natural reinforcement of 0.46 and 0.62% by weight of coir fiber was added. Fibers were analyzed by means of scanning electron microscope (SEM). Besides, an Eco-audit tool has been used to estimate energy and carbon emission of material, manufacturing, transportation, and disposal phases. It was found that fibers additions lowered the compressive strength compared to plain concrete. However, failures of the composites exhibited good post-cracking behavior. The use of vegetable fibers affects positively the life cycle of the material. Eco-audit results indicate that there is a potential to reduce between 9.15% and 13.35% of embodied energy and between 9.61% and 13.94% of CO2 during the material production phase. These suggest that coir fibers could be useful from the environmental view, although more studies regarding their durability are needed.Fibras de coco han sido examinadas por su sostenibilidad como refuerzo de concreto. Propiedades mecánicas y aspectos sostenibles de compuestos de concreto fueron estimadas luego de 7. 14, y 28 días de curado. Se adicionaron refuerzos naturales de 0.46 y 0.62% en peso de fibra de coco. Las fibras fueron analizadas mediante microscopía electrónica de barrido (SEM). Además, una herramienta de Eco-Auditoría se utilizó para estimar la energía y emisiones de carbono en las fases de material, manufactura, transporte y disposición. Se encontró que las adiciones de fibra disminuía la resistencia a la compresión comparado con el concreto normal. Sin embargo, las fallas de los compuestos exhibieron un buen comportamiento post-agrietamiento.  El uso de fibras vegetales afecta positivamente el ciclo de vida del material. Los resultados de la Eco-auditoría indican que hay un potencial para reducir la energía incorporada entre 9.15% y 13.35% y el CO2 entre 9.61% y 13.94% durante la fase de producción del material. Esto sugiere que las fibras de coco pueden ser útiles desde el punto de vista ambiental aunque son necesarios más estudios con relación a su durabilidad. &nbsp

Mechanical properties and sustainability aspects of coconut fiber modified concrete: Propiedades mecánicas y aspectos de sostenibilidad de concreto modificado con fibras de coco

Coir fiber has been examined for their suitability as reinforcement of concrete. Mechanical properties and sustainability aspects of concrete composites were estimated after 7. 14, and 28 days of curing. Natural reinforcement of 0.46 and 0.62% by weight of coir fiber was added. Fibers were analyzed by means of scanning electron microscope (SEM). Besides, an Eco-audit tool has been used to estimate energy and carbon emission of material, manufacturing, transportation, and disposal phases. It was found that fibers additions lowered the compressive strength compared to plain concrete. However, failures of the composites exhibited good post-cracking behavior. The use of vegetable fibers affects positively the life cycle of the material. Eco-audit results indicate that there is a potential to reduce between 9.15% and 13.35% of embodied energy and between 9.61% and 13.94% of CO2 during the material production phase. These suggest that coir fibers could be useful from the environmental view, although more studies regarding their durability are needed.Fibras de coco han sido examinadas por su sostenibilidad como refuerzo de concreto. Propiedades mecánicas y aspectos sostenibles de compuestos de concreto fueron estimadas luego de 7. 14, y 28 días de curado. Se adicionaron refuerzos naturales de 0.46 y 0.62% en peso de fibra de coco. Las fibras fueron analizadas mediante microscopía electrónica de barrido (SEM). Además, una herramienta de Eco-Auditoría se utilizó para estimar la energía y emisiones de carbono en las fases de material, manufactura, transporte y disposición. Se encontró que las adiciones de fibra disminuía la resistencia a la compresión comparado con el concreto normal. Sin embargo, las fallas de los compuestos exhibieron un buen comportamiento post-agrietamiento.  El uso de fibras vegetales afecta positivamente el ciclo de vida del material. Los resultados de la Eco-auditoría indican que hay un potencial para reducir la energía incorporada entre 9.15% y 13.35% y el CO2 entre 9.61% y 13.94% durante la fase de producción del material. Esto sugiere que las fibras de coco pueden ser útiles desde el punto de vista ambiental aunque son necesarios más estudios con relación a su durabilidad. &nbsp

Terror and morBBo in visuals of HIV/AIDS infection in Chile (1990-2018)

Este artículo analiza registros visuales de dos momentos históricos del VIH/sida en Chile. El primero de ellos se sitúa en la década de 1980 e incluye imágenes de prensa junto con imágenes y reflexiones en torno a obras de Juan Dávila y Las Yeguas del Apocalipsis. El segundo registro que se explora pertenece a comunidades de sexo bareback en Chile en redes sociales. El análisis recurre a las ideas de comunidad/inmunidad, sobre todo de Roberto Espósito, para observar y pensar ciertas nociones de la comunidad y sus límites. Se establece que, considerando significativas diferencias por las finalidades de las distintas imágenes, ellas muestran los cambios en la cultura sobre el VIH/sida en Chile y el paso de una cultura de lo inmune basada en el miedo a otra, en la cual se manifiestan grupos que promueven prácticas de “contagio” comunitario.This article analyzes images from two historical moments of HIV/AIDS in Chile. The first of these, dates back to the 1980s, and includes press images and the works of Juan Dávila and the Yeguas del Apocalipsis. The second register explored belongs to bareback sex communities in Chile and its social networks. The analysis uses the ideas of community/immunity, especially by Roberto Esposito, to observe some notions of community limits. It is established that, considering significant differences about the purposes of the images, they show the changes in the culture on HIV / AIDS in Chile, and the passage from a culture of the immune based on fear, to another, in which there are groups that promote practices of community “contagion”

Ramón Álvarez Palomo : una biografía militante

La vida de Ramón Alvarez Palomo está estrechamente ligada a las vicisitudes de la Confederación Nacional del Trabajo. Se trata de una persona que desde los quince años, edad a la que se afilió a la organización anarcosindicalista, no ha dejado de militar en la misma, y nos lo podemos encontrar asistiendo, protagonizando y conociendo de primera mano prácticamente todos los momentos claves que han ido marcando el desarrollo de la CNT desde 1928 hasta la actualidad. Este hecho marca intensamente su trayectoria vital, por lo que conocer la vida de Ramón Alvarez es, en gran medida, conocer la historia de la CNT.The life of Ramón Alvarez Palomo is closely linked to the vissicitudes of Confederación Nacional del Trabajo. He is a person who, from the time he was fifteen, when he became affiliated the anarquist-union, has never stopped being a member of the same. We can still find him attending, leading, and from first hand experience understanding practically all the significant moments which have marked the development of CNT, from 1982, until the present day. This fact has influenced his life very intensely. That is why knowing the life of Ramón Alvarez is knowing the history of CNT