Distribution and Origin of Iron Oxides in Soils over Limestone

[Resumen] Se pretende conocer la distribuci6n y el origen de los compuestos de hierro en suelos formados sobre calizas en Galicia. Predominan las formas minerales de hierro, encontrando en la fracción arena magnetita, goethita y/o hematites y excepcionalmente ilmenita, que se consideran heredadas del material de partida. En lámina delgada se observaron goethita y hematites como granos aislados, constituyendo nódulos e integrados en fragmentos de caliza. En la arcilla, trazas de goethita están presentes en casi todos los perfiles; s610 en uno de ellos la hematites es el único 6xido de hierro. La goethita puede haberse formado tanto por neoformaci6n como por microdivisi6n a partir de las fracciones gruesas, siendo este último fen6meno el que ha originado la hematites de la fracci6n arcilla. En dos perfiles la goethita va acompañada de magnetita y se discute la posible existencía y formaci6n de maghemita.[Abstract] Iron distribution in soils formed over limestone of Galicia is studied an the origin of the different iron forms is established. Organic iron is very scarce and mineral iron components dominate. Magnetite, goethite and / or hematite, less cornmonly ilmenite, are found in the sand fraction; they are considered as interited from the parent material. In polished sections goethite an hematite appear as single grains, nodules and il1corporated into limestone fragments. In the clay fraction, traces of goethite are present in aH except one of the profiles where only traces of hematite are indentified. Neoformation and microdivision from coarse fractions can act in the genesis of goethite; only microdivision is considered as the origin of hematite. Magnetite accompanies goethite in two profiles; the possible presence of maghemite and its origin is also discusse

New insights into the genetic etiology of Alzheimer's disease and related dementias.

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

The Great Markarian 421 Flare of 2010 February: Multiwavelength Variability and Correlation Studies

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of 2010 February, when an extraordinary flare reaching a level of ∼27 Crab Units above 1 TeV was measured in very high energy (VHE) γ-rays with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory. This is the highest flux state for Mrk 421 ever observed in VHE γ-rays. Data are analyzed from a coordinated campaign across multiple instruments, including VHE γ-ray (VERITAS, Major Atmospheric Gamma-ray Imaging Cherenkov), high-energy γ-ray (Fermi-LAT), X-ray (Swift, Rossi X-ray Timing Experiment, MAXI), optical (including the GASP-WEBT collaboration and polarization data), and radio (Metsahovi, Owens Valley Radio Observatory, University of Michigan Radio Astronomy Observatory). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare "decline" epochs. The main flare statistics allow 2 minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of ∼25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor (δ ⪆ 33) and the size of the emission region (δ-1RB≲ 3.8 × 1013cm) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10 minute binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship, from linear to quadratic to lack of correlation to anticorrelation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain with the classic single-zone synchrotron self-Compton model.</p

Indicadores de la estabilidad y madurez del compost

The authors specially thanks to Ediciones MUNDI-PRENSA by the authorization to include this archive of the published book, in the Institutional Repository DIGITAL CSIC https://digital.csic.esRED ESPAÑOLA DE COMPOSTAJE (REC) (SPANISH COMPOSTING NETWORK) funded by the Spanish Ministery of Science and Innovation as well as the Ministery of Environment. http://www.recompostaje.com CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS (CSIC). http://www.csic.e

Comparación de la estabilidad estructural de suelos de prado y cultivo

6 páginas, 4 figuras, 2 tablas, 14 referencias. Trabajo presentado al citado Simposio, Área temática 1: Calidad vs degradación de los suelos por actividades antrópicas, celebrado del 6-7, julio, 2005, en Madrid, España.[ES]: Se comparan las propiedades estructurales de dos suelos de la zona templado-húmeda española desarrollados sobre granito, dedicados a prado permanente y cultivo, a fin de valorar el impacto del tipo de manejo sobre la calidad estructural. El suelo de prado presentó unas propiedades estructurales más favorables, tales como una menor densidad aparente y mayor porosidad, un mayor tamaño medio de agregados, y una mayor estabilidad de los agregados frente a la agitación mecánica en agua y frente a la acción de la lluvia simulada. Esta mayor estabilidad estructural del suelo de prado se relaciona con su mayor contenido de materia orgánica (MOS). Asimismo, el suelo de prado presentó una mayor actividad microbiana, según se deduce de los valores más altos de respiración en experimentos de incubación, en comparación con el suelo de cultivo. El suelo de prado también presentó los valores más elevados de cociente respiratorio (C-CO2/C orgánico total), de lo que se deduce que la MOS del suelo de prado es más accesible a la degradación microbiana. Sin embargo no se observaron diferencias significativas entre la mineralización del carbono orgánico del suelo disgregado (<1mm) y de agregados intactos del mismo suelo (5-1 mm). Los resultados de este trabajo ponen en evidencia la necesidad de mantener niveles adecuados de MOS a través de enmiendas o reducción del laboreo.[EN]: We compared the structural properties of two neighbouring soils from the NW of Spain in order to evaluate the effect of management on structural quality. The soils were developed on granite under a warm and humid climate but differed in land use (pasture and cultivation). The pasture soil had more favourable structural properties than the cultivated soil, showing lower bulk density, higher porosity and water retention, higher mean aggregate diameter and aggregate stability against mechanical agitation in air and water, as well as lower soil loss under simulated rainfall. This increased structural stability of the pasture soil could be attributed to its elevated organic matter (OM) content. More C-CO2 was also released by OM mineralization in laboratory incubated pasture soil samples than in culture soils, due to higher microbial activity. Respiratory quotient (C-CO2/Corg total) was also higher in the pasture soil, thus indicating that the OM is more accessible to microbial decomposition. Nevertheless no significant differences were observed between organic C mineralization in disturbed ground soil <1 mm and undisturbed 5-1 mm aggregates. The overall results demonstrate the need to maintain adequate levels of OM by means of organic amendments or tillage reduction.Peer reviewe