Estudi aerodinàmic de l'aleró davanter d'un Fórmula E

La fórmula E és una competició de monoplaces elèctrics que organitza la Federació Internacional de l'Automòbil (FIA). La qual es l'expositor del desenvolupament de vehicles elèctrics per promoure i accelerar la seva popularitat. Aquesta categoria es va formar l'any 2014 i el proper 6 de Febrer començarà la segona temporada. Davant la popularització d'aquesta nova competició i en conseqüència, les poques dades que es poden obtenir bibliogràficament es decideix fer un estudi aerodinàmic de l'aleró davanter d'un monoplaça. Fer una aproximació a aquest amb la normativa que imposa la FIA a les escuderies participants. També es configurarà aquest component aerodinàmic depenent de les condicions del circuit on tindrà lloc els grans premis de Fórmula E

Carbon isotopes of graphite: Implications on fluid history

Stable carbon isotope geochemistry provides important information for the recognition of fundamental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elaboration of models for the global carbon cycle. Carbon isotope ratios in fluid-Deposited graphite are powerful tools for unravelling the ultimate origin of carbon (organic matter, mantle, or carbonates) and help to constrain the fluid history and the mechanisms involved in graphite deposition.Graphite precipitation in fluid-deposited occurrences results from CO2- and/or CH4-bearing aqueous fluids. Fluid flow can be considered as both a closed (without replenishment of the fluid) or an open system (with renewal of the fluid by successive fluid batches). In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipitation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment (depending upon the dominant carbon phase in the fluid, CO2 or CH4, respectively). In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of d13C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation

The effects of habitat and prey availability on otter (Lutra lutra) diet and distribution in the Sierra Norte de Sevilla Natural Park

La nutria está ampliamente distribuida en el Parque Natural Sierra Norte de Sevilla y en su entorno inmediato. En el área de estudio la nutria tendió a intensificar el uso del hábitat desde los tramos de cabecera hacia los tramos más bajos. Como era de esperar la disponibilidad de alimento fue también un factor decisivo para explicar el uso del hábitat por la nutria. El análisis de la dieta reveló que la presa más importante fue el barbo (Barbus sclateri). Existió una elevada correlación entre el tamaño medio y máximo de los barbos y el uso del hábitat por la nutria, de manera que ésta utilizó más los tramos con barbos de mayor talla. Esta misma correlación se observó también para las bogas (Chondrostoma willkommii). La nutria consumió hasta 20 tipos de presas distintas en el área de estudio: 11 especies de peces (barbo, calandino, pez sol, colmilleja, cachuelo, boga, pardilla y trucha), siete vertebrados no peces (rana, sapo, urodelos, culebra de agua, aves y micromamíferos) y dos invertebrados (cangrejo rojo americano e insectos). De todas ellas las más importantes, en orden decreciente, fueron el barbo, seguido a gran distancia por el cangrejo rojo (Procambarus clarkii) y la rana común (Rana perezi). En conjunto, en este resultado destaca sobremanera la importancia que adquirieron los peces en la dieta de la nutria. El 61% de los individuos consumidos y el 84% de la biomasa correspondió a peces. La dieta de la nutria varió según las condiciones ambientales y, en general, se ajustó a las presas disponibles en cada lugar. Sin embargo, cuando se comparó la abundancia de presas en el medio y en la dieta se observó que la nutria mostró preferencia o rechazo por algunas especies y/o tallas de las que seleccionó las mayores, salvo en el caso del pez sol (Lepomis gibbosus), en el que este patrón se invertía. En la situación actual y a la luz de los resultados obtenidos se puede concluir que el estado de conservación de la nutria en el Parque Natural Sierra Norte de Sevilla parece bueno o muy bueno.__________________________The otter is widespread through all the Parque Natural Sierra Norte de Sevilla and surrounding areas. We found that the otter varied its intensity of use of habitat in the course of the portion of the longitudinal gradient defined as headwaters-middle reaches. The otter tended to use more intensively middle reaches instead of headwaters, related to food sources availability. The otter fed on 20 different preys: 11 different freshwater fish species (The Iberian barbell, calandino, the sun fish, the Iberian sandsmelt, the Iberian chub, the Iberian nase, pardilla and common trout), seven vertebrates no fishes (common frogs, common toads, urodels, water snakes, birds y micromamifers) and two invertebrates (the red swamp crayfish and insects). Within all these preys the Iberian barbell (Barbus sclateri), the red swamp crayfish (Procambarus clarkii) and common frog (Rana perezi) stood out in this order of preference. 61% of preys and 84% of total biomass corresponded to freshwater fish individuals. This fact underlines the high importance that freshwater fishes had for the otters´ diet within the study area. However, otter’s diet showed a faithfully pattern in relation to preys availability, since they mainly fed on the most available preys. This general pattern must be specified, as the otter tended to select or reject some fish species and/or fish sizes. Long sized fishes were specially consumed except for the sun fish (Lepomis gibbosus) with which this general pattern appeared inverted. In summary we can say that the Sierra Norte´s otter population is in good or very good health

Contrasting Mineralizing Processes in Volcanic-Hosted Graphite Deposits

The only two known graphite vein-deposits hosted by volcanic rocks (Borrowdale, United Kingdom, and Huelma, Southern Spain) show remarkable similarities and differences. The lithology, age of the magmatism and geodynamic contexts are distinct, but the mineralized bodies are controlled by fractures. Evidence of assimilation of metasedimentary rocks by the magmas and hydrothermal alteration are also common features to both occurrences. Graphite morphologies at the Borrowdale deposit vary from flakes (predominant) to spherulites and cryptocrystalline aggregates, whereas at Huelma, flaky graphite is the only morphology observed. The structural characterization of graphite indicates a high degree of ordering along both the c axis and the basal plane. Stable carbon isotope ratios of graphite point to a biogenic origin of carbon, most probably related to the assimilation of metasedimentary rocks. Bulk į13C values are quite homogeneous in both occurrences, probably related to precipitation in short time periods. Fluid inclusion data reveal that graphite precipitated from C-O-H fluids at moderate temperature (500 ºC) in Borrowdale and crystallized at high temperature from magma in Huelma, In addition, graphite mineralization occurred under contrasting fO2 conditions. All these features can be used as potential exploration tools for volcanic-hosted graphite deposits

Assimilation, Hydrothermal Alteration and Graphite Mineralization in the Borrowdale Deposit (UK)

The volcanic-hosted graphite deposit at Borrowdale was formed through precipitation from C-O-H fluids. The G13C data indicate that carbon was incorporated into the mineralizing fluids by assimilation of carbonaceous metapelites of the Skiddaw Group by andesite magmas of the Borrowdale Volcanic Group. The graphite mineralization occurred as the fluids migrated upwards through normal conjugate fractures forming the main subvertical pipe-like bodies. The mineralizing fluids evolved from CO2-CH4-H2O mixtures (XCO2=0.6-0.8) to CH4-H2O mixtures. Coevally with graphite deposition, the andesite and dioritic wall rocks adjacent to the veins were intensely hydrothermally altered to a propylitic assemblage. The initial graphite precipitation was probably triggered by the earliest hydration reactions in the volcanic host rocks. During the main mineralization stage, graphite precipitated along the pipe-like bodies due to CO2 -> C+O2. This agrees with the isotopic data which indicate that the first graphite morphologies crystallizing from the fluid (cryptocrystalline aggregates) are isotopically lighter than those crystallizing later (flakes). Late chlorite-graphite veins were formed from CH4-enriched fluids following the reaction CH4 + O2 -> C+ 2H2O, producing the successive precipitation of isotopically lighter graphite morphologies. Thus, as mineralization proceeded, water-generating reactions were involved in graphite precipitation, further favouring the propylitic alteration

Assimilation, Hydrothermal Alteration and Graphite Mineralization in the Borrowdale Deposit (UK)

The volcanic-hosted graphite deposit at Borrowdale was formed through precipitation from C-O-H fluids. The G13C data indicate that carbon was incorporated into the mineralizing fluids by assimilation of carbonaceous metapelites of the Skiddaw Group by andesite magmas of the Borrowdale Volcanic Group. The graphite mineralization occurred as the fluids migrated upwards through normal conjugate fractures forming the main subvertical pipe-like bodies. The mineralizing fluids evolved from CO2-CH4-H2O mixtures (XCO2=0.6-0.8) to CH4-H2O mixtures. Coevally with graphite deposition, the andesite and dioritic wall rocks adjacent to the veins were intensely hydrothermally altered to a propylitic assemblage. The initial graphite precipitation was probably triggered by the earliest hydration reactions in the volcanic host rocks. During the main mineralization stage, graphite precipitated along the pipe-like bodies due to CO2 -> C+O2. This agrees with the isotopic data which indicate that the first graphite morphologies crystallizing from the fluid (cryptocrystalline aggregates) are isotopically lighter than those crystallizing later (flakes). Late chlorite-graphite veins were formed from CH4-enriched fluids following the reaction CH4 + O2 -> C+ 2H2O, producing the successive precipitation of isotopically lighter graphite morphologies. Thus, as mineralization proceeded, water-generating reactions were involved in graphite precipitation, further favouring the propylitic alteration

Conditions of graphite precipitation in the volcanic-hosted deposits at Borrowdale (Cumbria, UK)

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Distribution, ecology and conservation of the freshwater fish in the Sierra Norte de Sevilla Natural Park

En el Parque Natural Sierra Norte de Sevilla y su entorno inmediato habitan 13 especies de peces continentales: anguila (Anguilla anguilla), trucha común (Salmo trutta), trucha arco-iris (Oncorhynchus mykiss), barbo (Barbus sclateri), pardilla (Chondrostoma lemmingii), boga (Chondrostoma willkommii), carpa común (Cyprinus carpio), calandino (Squalius alburnoides), cachuelo (Squalius pyrenaicus), colmilleja (Cobitis paludica), gambusia (Gambusia holbrooki), pez sol (Lepomis gibbosus), blacbás (Micropterus salmoides). De ellas ocho son nativas (61,5%) (anguila, trucha común, barbo, pardilla, boga, calandino, cachuelo y colmilleja) y cinco introducidas (trucha arco-iris, carpa, gambusia, pez sol y blacbás) (38,5%). En este trabajo se aborda el análisis general de este componente esencial de la biodiversidad acuática, desde su distribución, hasta sus preferencias de hábitat, pasando por el estudio de las relaciones entre especies exóticas y nativas o el impacto de los embalses sobre los patrones observados. El trabajo finaliza con el diagnostico de su estado de conservación y la propuesta de algunas directrices para su gestión._________________________Thirteen different freshwater fish species inhabit the Parque Natural Sierra Norte de Sevilla and surrounding areas: eel (Anguilla Anguilla), common trout (Salmo trutta), brown trout (Oncorhynchus mikiss), Iberian barbell (Barbus sclateri), pardilla (Chondrostoma lemmingii), iberian nase (Chondrostoma willkommii), carp (Cyprinus carpio), calandino (Squalius alburnoides), Iberian chub (Squalius pyrenaicus), Iberian sand-smelt (Cobitis paludica), mosquito fish (Gambusia holbrooki), sun fish (Lepomis gibbosus) and largemouth bass (Micropterus salmoides). This community comprised 8 natives (61.5%) (eel, common trout, Iberian barbell, pardilla, Iberian nase, calandino, Iberian chub and Iberian sand-smelt) and 5 exotics (brown trout, carp, mosquito fish, sun fish and largemouth bass). In this study we tackle from general aspects of spatial distribution of species or habitat preferences, to specific ecological relationships between native and exotic species or the effect of reservoirs on the observed ecological patterns. Additionally, we deal with a general diagnosis of the freshwater fish biodiversity’s conservation status within Sierra Norte and we provide with some management advices to preserve it. Resumen Abstract Distribución, ecología y estado de conservación de la ictiofauna del Parque Natural Sierra Norte de Sevilla Distribution, ecology and conservation of the freshwater fish in the Sierra Norte de Sevilla Natural Park