Iron and carbon geochemistry of sediment core GeoB1401-4

Iron speciation was determined in hemiplegic sediments from a high productivity area to investigate systematically the early diagenetic reactivity of Fe. A combination of various leaching agents (1 M HCI, dithionite buffered in citrate/acetic acid, HF/H2SO4, acetic Cr(II)) was applied to sediment and extracted more than 80% of total Fe. Subsequent Fe species determination defined specific mineral fractions that are available for Fe reduction and fractions formed as products of Fe diagenesis. To determine the Fe speciation of (sheet) silicates we explored an extraction procedure (HF/H2SO4) and verified the procedure by application to standard rocks. Variations of Fe speciation of (sheet) silicates reflect the possible formation of Fe-bearing silicates in near surface sediments. The same fraction indicates a change in the primary input at greater depth, which is supported by other parameters. The Fe(II)/ Fe(III) -ratio of total sediment determined by extractions was compared with Mössbauer-spectroscopy ] at room temperature and showed agreement within 10%. M6ssbauer-spectroscopy indicates the occurrence of siderite in the presence of free sulfide and pyrite, supporting the importance of microenvironments during mineral formation. The occurrence of other Fe(II) bearing minerals such as ankerite (Ca-, Fe-, Mg-carbonate) can be presumed but remains speculative.

Climatic records of the late Holocene from sediment core GeoB9504-3 off Senegal

High-resolution climatic records of the late Holocene along the north-west African continental margin are scarce. Here we combine sediment grain size, elemental distribution and mineral assemblage data to trace dust and riverine sources at a shallow-marine sediment depocentre in the vicinity of the Senegal River mouth. The aim is to understand how these terrigenous components reflect climate variability during the late Holocene. Major element contents were measured and mineral identification was performed on three sub-fractions of our sediment core: (i) fluvial material <2 µm, (ii) aeolian material of 18-63 µm and (iii) a sub-fraction of dual-origin material of 2-18 µm. Results show that more than 80% of the total Al and Fe terrigenous bulk content is present in the fluviogenic fraction. In contrast, Ti, K and Si cannot be considered as proxies for one specific source off Senegal. The Al/Ca ratio, recording the continental river runoff, reveals two dry periods from 3010 to 2750 cal a BP and from 1900 to 1000 cal a BP, and two main humid periods from 2750 to 1900 cal a BP and from 1000 to 700 cal a BP. The match between (i) intervals of low river runoff inferred by low Al/Ca values, (ii) reduced river discharge inferred by integrated palynological data from offshore Senegal and (iii) periods of enhanced dune reactivation in Mali confirms this interpretation.

Consumers mediate the effects of experimental ocean acidification and warming on primary producers

It is well known that ocean acidification can have profound impacts on marine organisms. However, we know little about the direct and indirect effects of ocean acidification and also how these effects interact with other features of environmental change such as warming and declining consumer pressure. In this study, we tested whether the presence of consumers (invertebrate mesograzers) influenced the interactive effects of ocean acidification and warming on benthic microalgae in a seagrass community mesocosm experiment. Net effects of acidification and warming on benthic microalgal biomass and production, as assessed by analysis of variance, were relatively weak regardless of grazer presence. However, partitioning these net effects into direct and indirect effects using structural equation modeling revealed several strong relationships. In the absence of grazers, benthic microalgae were negatively and indirectly affected by sediment-associated microalgal grazers and macroalgal shading, but directly and positively affected by acidification and warming. Combining indirect and direct effects yielded no or weak net effects. In the presence of grazers, almost all direct and indirect climate effects were nonsignificant. Our analyses highlight that (i) indirect effects of climate change may be at least as strong as direct effects, (ii) grazers are crucial in mediating these effects, and (iii) effects of ocean acidification may be apparent only through indirect effects and in combination with other variables (e.g., warming). These findings highlight the importance of experimental designs and statistical analyses that allow us to separate and quantify the direct and indirect effects of multiple climate variables on natural communities.

Genome-Wide Analysis of the Response of Dickeya dadantii 3937 to Plant Antimicrobial Peptides

Antimicrobial peptides constitute an important factor in the defense of plants against pathogens, and bacterial resistance to these peptides have previously been shown to be an important virulence factor in Dickeya dadantii, the causal agent of soft-rot disease of vegetables. In order to understand the bacterial response to antimicrobial pep- tides, a transcriptional microarray analysis was performed upon treatment with sub-lethal concentration of thionins, a widespread plant peptide. In all, 36 genes were found to be overexpressed, and were classified according to their deduced function as i) transcriptional regulators, ii) transport, and iii) modification of the bacterial membrane. One gene encoding a uricase was found to be repressed. The majority of these genes are known to be under the control of the PhoP/PhoQ system. Five genes representing the different functions induced were selected for further analysis. The results obtained indicate that the presence of antimicrobial peptides induces a complex response which includes peptide-specific elements and general stress-response elements contributing differentially to the virulence in different hosts.

About the origin of low wafer performance and crystal defect generation on seed-cast growth of industrial mono-like silicon ingots

The era of the seed-cast grown monocrystalline-based silicon ingots is coming. Mono-like, pseudomono or quasimono wafers are product labels that can be nowadays found in the market, as a critical innovation for the photovoltaic industry. They integrate some of the most favorable features of the conventional silicon substrates for solar cells, so far, such as the high solar cell efficiency offered by the monocrystalline Czochralski-Si (Cz-Si) wafers and the lower cost, high productivity and full square-shape that characterize the well-known multicrystalline casting growth method. Nevertheless, this innovative crystal growth approach still faces a number of mass scale problems that need to be resolved, in order to gain a deep, 100% reliable and worldwide market: (i) extended defects formation during the growth process; (ii) optimization of the seed recycling; and (iii) parts of the ingots giving low solar cells performance, which directly affect the production costs and yield of this approach. Therefore, this paper presents a series of casting crystal growth experiments and characterization studies from ingots, wafers and cells manufactured in an industrial approach, showing the main sources of crystal defect formation, impurity enrichment and potential consequences at solar cell level. The previously mentioned technological drawbacks are directly addressed, proposing industrial actions to pave the way of this new wafer technology to high efficiency solar cells.

La forma del agua. Temas e invariantes en el jardín y el paisaje. Análisis de casos (Holanda-España, 1548-1648)

El espacio geográfico, entendido como territorio que da soporte a la vida y a la civilización, ha estado siempre fuertemente supeditado a la presencia de agua. Desde la Prehistoria el hombre otorgó al agua, junto a otros elementos que aseguraban o protegían su vida, un valor superior, por encima de lo humano. Paralelamente y de manera natural, el jardín, en sus inicios en estrecha relación con la agricultura y con el paisaje, fue el ámbito idóneo para la creación de nuevas formas acuáticas artificiales. Este proceso dio lugar a un extenso repertorio de formas compositivas que parece que tuvo en el Renacimiento un punto de inflexión, en el que se observa como la mayoría de recursos y configuraciones básicas del agua estaban ya plenamente establecidas. Esta evolución y sus resultados ha sido el objeto de la primera parte de la tesis: su objetivo ha sido analizar cómo el agua configura, cualifica o puede llegar a construir el jardín y el territorio en el que se inserta, así como establecer las posibles relaciones entre estos dos ámbitos de estudio. Aunque la historia es su fundamento, el planteamiento aquí ha sido más bien conceptual; estudiando los componentes acuáticos desde un punto de vista fundamentalmente compositivo. Esta indagación previa ha sido indispensable para llegar a entender en profundidad los modos en los que el agua se muestra en el jardín y en el paisaje renacentista y manierista, momentos en que se insertan los dos casos de estudio que constituyen la segunda parte de la tesis. Sin caer en un determinismo geográfico extremo, puede admitirse que el jardín, como manifestación cultural intrínsecamente ligada al entorno, depende fuertemente del territorio en el que se asienta; hecho particularmente evidente en aquellas regiones en las que su especial geografía ha sido un claro factor condicionante de su historia. Por ello, Holanda y España han sido las dos localizaciones elegidas para profundizar en este estudio; no tanto por su estrecha relación política y cultural, sino por su profundo y sugerente contraste de medio físico y climático. La Península Ibérica, geográficamente el término del mundo conocido en Occidente hasta el final de la Edad Media, y por esta circunstancia convertida en destino, en territorio de permanencia y fusión, estará además supeditada en la mayoría de su territorio a la falta de agua, siendo a la vez heredera directa del universo y la tradición del jardín meridional originario de Oriente. En el extremo opuesto, Holanda, espacio de transición entre el mar y la tierra firme “real”, es un territorio permeado de humedad y surcado con generosidad por grandes ríos. El país, con una relación ambivalente con el agua, unas veces como amenaza y otras como fuente de nuevas oportunidades, será por el contrario especialmente favorable para el desarrollo de un modelo de jardín septentrional. Un jardín del norte, que no obstante, no surgirá de despejar los bosques, como en el arquetipo nórdico, sino que crecerá sobre planicies antes saturadas de agua o directamente anegadas. El marco temporal de los dos casos concretos ha considerado como fecha inicial 1548, momento en el que Felipe II, aún príncipe, realizó su primer viaje a los Países Bajos, y entró en contacto con el modelo holandés. La extensa producción posterior de jardines de Felipe II, siempre con el agua como protagonista, tuvo como destacado referente la adaptación al suelo y la geografía hispánicos de dicho modelo. Como fecha final se fija 1648, justo un siglo después, fecha coincidente con la firma de la Paz de Westfalia, tratado que supone la total reorganización política del territorio europeo y la pérdida de la hegemonía española en Europa. En Holanda sólo dos años después nacerá Guillermo III de Orange, estatúder de las Provincias Unidas, también futuro rey de Inglaterra, Escocia e Irlanda. Para entonces en Holanda ya se había asistido al desarrollo de un arte propio de jardín, íntimamente ligado al agua, sorprendentemente no demasiado bien conocido y que será uno de los temas de esta investigación. Finalmente, se propone una lectura conjunta de toda esta serie de intervenciones que tienen como argumento el agua, en la que se integra la información procedente de distintos campos de estudio, cada una con su metodología particular. El resultado es una tesis en la que el jardín y el territorio son tratados desde un nuevo y enriquecedor punto de vista. ABSTRACT Geographical space, understood as the territory that provides support to human life and civilization, has always been strongly subjected to the presence of water. From Prehistory man gave to water, along with other elements that ensured or protected life, a higher value than the merely human. At the same time and in a natural way, the garden, in its beginnings with a close relationship with agriculture and landscape, soon developed as the appropriate ground for the creation of new artificial aquatic forms, in a process that seems to have a turning point in the Renaissance, when most of the basic waterworks and resources were already fully established. This development and its outcomes are the subjects of the first part of the thesis: its scope has been to analyse how water configures, qualifies and might even help to construct the garden or landscape attached to it; and to establish the possible links between these two fields of study. Although history based, the point of view here is mainly conceptual, studying the water components understood as composite elements. This exploratory research has been essential to deeply understand the water patterns shown in the Renaissance and Mannerist garden and landscape, periods in which the two case studies are inserted. Without falling in extreme determinism, it can be accepted however, that garden, as a cultural expression linked to environment, is strongly dependant on territorial setting; something particularly evident in those areas where specific geography has been a clear history conditioning factor. This is the reason that leads to choose the Netherlands and Spain to deepen this study, no so much for their interesting cultural and politics relations as for the suggestive and profound contrast of their physical environment and climate. The Iberian Peninsula, geographically the limit of the known world in Occident until the end of the Medium Age, and by this circumstance understood as endpoint, more a destination than a crossroad, a territory of permanence and fusion, but also subjected to water shortage; is thus associated with the universe and tradition of the meridional garden imported from Orient. In the opposite, the Netherlands, a transitional space between the sea and the “real” firm land, is a territory permeated by water and crossed by big rivers. Always with an ambivalent relationship with water, sometimes seen as a threat and sometimes as a source of new opportunities, it was in the other hand the adequate land for the development of a special model of Northern garden. A garden that will not arise, however, from the clearing of woods as in the Nordic archetype, but that will grow on plains originally saturated of water or directly waterlogged. The timeframe of the two cases has 1548 as the initial year, moment in which Philip II, yet prince, made his first trip to the Low Lands and imbibed the Dutch garden model. The later and bountiful garden works of the king, always with the water as the main focus, adapted the imported model to the Spanish ground and geography. The final date is fixed in 1648, just a century after, in coincidence with the Westfalia Peace; a treaty that implied the total political reorganization of the European territory and the end of the Spanish hegemony in the continent. In Holland, only two years later, William III of Orange, Stadtholder of the United Provinces and also future king of England, Scotland and Ireland, was born. But by then the Netherlands had developed an own garden art, closely linked to water. This type garden, surprisingly not very well known, and its relationship with water, will be other of the addressing questions of this work. Finally, the investigation merges the different interventions that have water as an argument, integrating all the fields considered with their particular methodological approaches. The final result is a thesis in which garden and territory are treated from a new and enriching perspective.

Cardioprotection from ischemia by a brief exposure to physiological levels of ethanol: Role of epsilon protein kinase C

Recent epidemiological studies indicate beneficial effects of moderate ethanol consumption in ischemic heart disease. Most studies, however, focus on the effect of long-term consumption of ethanol. In this study, we determined whether brief exposure to ethanol immediately before ischemia also produces cardioprotection. In addition, because protein kinase C (PKC) has been shown to mediate protection of the heart from ischemia, we determined the role of specific PKC isozymes in ethanol-induced protection. We demonstrated that (i) brief exposure of isolated adult rat cardiac myocytes to 10–50 mM ethanol protected against damage induced by prolonged ischemia; (ii) an isozyme-selective ɛPKC inhibitor developed in our laboratory inhibited the cardioprotective effect of acute ethanol exposure; (iii) protection of isolated intact adult rat heart also occurred after incubation with 10 mM ethanol 20 min before global ischemia; and (iv) ethanol-induced cardioprotection depended on PKC activation because it was blocked by chelerythrine and GF109203X, two PKC inhibitors. Consumption of 1–2 alcoholic beverages in humans leads to blood alcohol levels of ≈10 mM. Therefore, our work demonstrates that exposure to physiologically attainable ethanol levels minutes before ischemia provides cardioprotection that is mediated by direct activation of ɛPKC in the cardiac myocytes. The potential clinical implications of our findings are discussed.