926 research outputs found

    S wave velocity structure below central Mexico using high-resolution surface wave tomography

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    Shear wave velocity of the crust below central Mexico is estimated using surface wave dispersion measurements from regional earthquakes recorded on a dense, 500 km long linear seismic network. Vertical components of regional records from 90 well-located earthquakes were used to compute Rayleigh-wave group-velocity dispersion curves. A tomographic inversion, with high resolution in a zone close to the array, obtained for periods between 5 and 50 s reveals significant differences relative to a reference model, especially at larger periods (>30 s). A 2-D S wave velocity model is obtained from the inversion of local dispersion curves that were reconstructed from the tomographic solutions. The results show large differences, especially in the lower crust, among back-arc, volcanic arc, and fore-arc regions; they also show a well-resolved low-velocity zone just below the active part of the Trans Mexican Volcanic Belt (TMVB) suggesting the presence of a mantle wedge. Low densities in the back arc, inferred from the low shear wave velocities, can provide isostatic support for the TMVB

    Beet silage: chemical composition, fermentacion parameters and use of NIRS Technology as a tool to identify ensiled beet varieties

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    8 páginas, 2 figuras, 4 tablas.--Comunicación presentada a la 53ª Reunión Científica de la Sociedad Española para el Estudio de los Pastos (SEEP). "Pastos y PAC 2014-2020"[EN] The use of beet root for the purpose of feeding the dairy cattle could be constrained by the scarce knowledge about the characteristics of this feed after it has been ensiled. To investigate the feasibility of using the NIRS methodology to analyze the chemical composition of ensiled beets and to discriminate between beet varieties, roots of four beet varieties were ensiled (Sandrina KWS 1193, Tilly KWS 2733, Gerty KWS 2734 and Páramo 3359) using laboratory silos (600 ml of capacity). Although small differences (P<0.05) in chemical composition were found between treatments, the range of variation was narrow, especially for crude protein, which reached low and quite uniform values. The pH values were lower than 4 for all the varieties and the fermentation was mainly acetic. Whereas NIRS spectra of raw silages did not allow beet varieties discrimination or chemical composition prediction, spectra from dried and milled samples suggest that NIRS technology could be used as a tool for both purposes. NIRS spectra of silage juices could also be useful to establish beet variety.[ES] El empleo de raíces de remolacha en la alimentación del vacuno de leche se ve limitado por el escaso conocimiento acerca de las características de este alimento una vez ensilado. Para estudiar la composición química y los principales parámetros de fermentación de ensilados de remolacha y explorar la posibilidad de emplear la tecnología de espectroscopía de reflectancia en el infrarrojo cercano (NIRS) para la estimación de los parámetros estudiados y para discriminar distintas variedades de remolacha, se ensilaron raíces de cuatro variedades de remolacha (Sandrina KWS 1193, Tilly KWS 2733, Gerty KWS 2734 y Páramo 3359) empleando micro-silos de 600 ml de capacidad. Se detectaron diferencias (P<0,05) entre variedades en todos los parámetros de composición química de los ensilados, aunque en el caso de la proteína sólo la variedad Tilly KWS 2733 presentó un contenido diferente (P<0,05) a los del resto de las variedades. El pH alcanzó valores menores que 4 para todas las variedades y la fermentación fue principalmente acética. Los espectros NIRS de las muestras de ensilado en fresco no permitieron ni discriminar entre las variedades ensiladas ni predecir la composición química. Sin embargo, los resultados con las muestras secas y molidas sí apuntan la posibilidad de emplear la tecnología NIRS con ambos fines. Los espectros NIRS de los jugos del ensilado también podrían resultar útiles para establecer la variedad de remolacha ensilada.Este trabajo se financió con el contrato asociado a proyecto CDTI titulado: Procesado y estudio de variedades de remolacha para su utilización en alimentación animal (código 100102120005). Organismo financiador: INDUSTRIAS DE NUTRICIÓN ANIMAL, S.L.Peer reviewe

    Effects of climate, species interactions, and dispersal on decadal colonization and extinction rates of Iberian tree species

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    We studied the relative importance of climate, abundance of potentially competing species, and dispersal in explaining local colonization and extinction rates of tree species throughout mainland Spain. We used a Bayesian framework to parameterize a patch occupancy model to 23 species censused in 46,596 permanent plots in a 1 × 1 km grid across most Spanish forests. For most species, dispersal was the single best predictor of colonization, whereas climate and dispersal were equally important as predictors of extinction. Precipitation was positively correlated with the colonization rate of 12 out of 13 deciduous broad-leaved species, and negatively correlated with the extinction rate of nine of them. In contrast, precipitation equally decreased colonization and extinction of five out of eight of needle-leaved species (Juniperus and Pinus spp.). There was, however, marked variation among species in the magnitude of these effects, with some species exhibiting contrasting patterns for the colonization and the extinction process. Abundance of competing tree species (= summed plot basal area) was consistently correlated with decreased colonization of all needle-leaved species, and it increased the extinction rate of 6 out of 8 of these species. It had, nonetheless, weak facilitative effect on some broad-leaved species by promoting colonization (3 of 13 species) and decreasing extinction (7 of 13 species). With local colonization and extinction data, non-equilibrial and dynamic species distribution modelling can be improved by incorporating measures of biotic interactions and dispersal effects, along with traditional climate variables.Ministerio de Economía y CompetitividadComunidad de Madri

    Effects of climate, species interactions, and dispersal on decadal colonization and extinction rates of Iberian tree species

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    We studied the relative importance of climate, abundance of potentially competing species, and dispersal in explaining local colonization and extinction rates of tree species throughout mainland Spain. We used a Bayesian framework to parameterize a patch occupancy model to 23 species censused in 46,596 permanent plots in a 1 × 1 km grid across most Spanish forests. For most species, dispersal was the single best predictor of colonization, whereas climate and dispersal were equally important as predictors of extinction. Precipitation was positively correlated with the colonization rate of 12 out of 13 deciduous broad-leaved species, and negatively correlated with the extinction rate of nine of them. In contrast, precipitation equally decreased colonization and extinction of five out of eight of needle-leaved species (Juniperus and Pinus spp.). There was, however, marked variation among species in the magnitude of these effects, with some species exhibiting contrasting patterns for the colonization and the extinction process. Abundance of competing tree species (= summed plot basal area) was consistently correlated with decreased colonization of all needle-leaved species, and it increased the extinction rate of 6 out of 8 of these species. It had, nonetheless, weak facilitative effect on some broad-leaved species by promoting colonization (3 of 13 species) and decreasing extinction (7 of 13 species). With local colonization and extinction data, non-equilibrial and dynamic species distribution modelling can be improved by incorporating measures of biotic interactions and dispersal effects, along with traditional climate variables.Ministerio de Economía y CompetitividadComunidad de Madri

    Biosynthesis of Antitumoral and Bactericidal Sanguinarine

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    A simple, rapid, and reliable TLC method for the separation and determination of sanguinarine has been established. This intensively studied biologically active alkaloid has a wide range of potentially useful medicinal properties, such as antimicrobial, antiinflammatory, and antitumoral activities. Sanguinarine has also been incorporated into expectorant mixtures and has a strong bactericidal effect upon gram-positive bacteria, particularly Bacillus anthracis and staphylococci. These medicinal properties are due to the interaction of sanguinarine with DNA. A fibre-optic-based fluorescence instrument for in situ scanning was used for quantitative measurements. The sanguinarine was determined over the range 5–40 ng and a detection limit of 1.60 ng. The method was applied to the quantification of sanguinarine in tissue culture extracts of Chelidonium majus L

    Pseudoaneurisma de la arteria geniculada superior lateral secundaria a artroplastia de rodilla: Aportación de un caso

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    El pseudoaneurisma es una complicación infrecuente en la cirugía ortopédica de rodilla. Los pocos casos descritos generalmente están en relación con cirugía artroscópica. Presentamos un caso de pseudoaneurisma de la arteria geniculada superolateral secundario a artroplastia de rodilla en un varón de 69 años. El diagnóstico se realizó mediante arteriografía. Se trató con éxito mediante hemostasia y resección química.Pseudoaneurysm is an uncommon complication in knee orthopaedic surgery. There are few cases reported an most of them are secondary to arthroscopic techniques. We report a case of pseudoaneurysm of the superolateral genicular artery after knee arthroplasty in a 69-year-old-man. The diagnosis was made with arteriographay, and treatment was a successful hemostasia and surgical resection

    Evaluating the combined effects of climate and land-use change on tree species distributions

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    A large proportion of the world's biodiversity is reportedly threatened by habitat loss and climate change. However, there are few studies that investigate the interaction between these two threats using empirical data.Here, we investigate interactions between climate change and land use change in the future distribution of 23 dominant tree species in mainland Spain. We simulated changes up to year 2100 using a climate-dependent Stochastic Patch Occupancy Model, parameterized with colonization and extinction events recorded in 46 569 survey plots.We estimated that the distribution of 17 out of 23 tree species are expanding, and hence not at equilibrium with the climate. However, climate change will make the future occupancy of 15 species lower than expected if climate, and habitat, remained stable (baseline scenario).Climate change, when combined with 20% habitat loss, was estimated to reduce species occupancy by an average of 23% if habitat loss is spatially clumped, relative to baseline projections, and by 35% if scattered. If habitat loss occurred in areas already impacted by human activities, species occupancy would be reduced by 26%. Land-use changes leading to habitat gain (i.e. creation through e.g. reforestation), could slightly mitigate the effects of climate change; but a 20% increment in habitat would reduce climate-change-driven losses in species occupancy by only ~3%.Synthesis and applications. The distributions of the most common tree species in mainlandSpain are expanding, but climate change threatens to reduce this expansion by 18% for 15of the 23 studied species. Moreover, if the habitat of these species is simultaneously lost, theoccupancies of all of them will be reduced further, with variation depending on the spatialpattern of the lost habitats. However, we did not detect synergies between climate change andhabitat loss. The combined effect (with 20% habitat loss) was 5–13% less than what it wouldbe if the effects were additive. Importantly, reforestation could partially offset the negativeeffects of climate change, but complete mitigation would require an increase in forested landof 80%, and the prioritization of territories that are less impacted by human activities.Ministerio de Economía y CompetitividadComunidad de Madri

    Fibrohistiocitoma maligno óseo tras degeneración de enfermedad de Paget Caso clínico y revisión de la literatura

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    El fibrohistiocitoma maligno óseo es un tumor de estirpe mesenquimal poco frecuente, pero de alta agresividad. Se suele presentar de forma primaria, aunque a veces lo hace sobre lesiones previas en el hueso. Puede ser difícil de diferenciar histológicamente de otros tumores, pero es una entidad propia desde el punto de vista anatomopatológico. Presentamos un paciente con enfermedad de Paget que desarrolló un fibrohistiocitoma maligno óseo en el fémur sobre el hueso pagético. Fue tratado mediante desarticulación de cadera. No se usó quimioterapia como tratamiento coadyuvante debido a su avanzada edad y situación basal. A los 18 meses se encuentra asintomático y sin signos de recurrencia. Se hace una revisión de la literatura acerca de este tumor.Malignant fibrous histiocytoma of bone is a rare but highly agressive mesenchimal tumor. It usually arises as a primary tumor but sometimes it can be associated with pre-existing bone abnormalities. Histologically it can be missdiagnosed with other tumors. We report a case of malignant fibrous histiocytoma of bone in the femur in a patient with Paget's disease treated by hip desarticulation. We didn't use chemotherapy because his elderly status. At 18 months follow up, the patient is symptom-free and neither local recurrence nor metastasis have been found. A review of the literature has been carried out

    Energy loss of H+ and H2+ beams in carbon nanotubes: a joint experimental and simulation study

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    Carbon nanotube properties can be modified by ion irradiation; therefore it is important to know the manner in which ions deposit energy (how much and where) in the nanotubes. In this work, we have studied, experimentally and with a simulation code, the irradiation of multi-walled carbon nanotubes (MWCNT), supported on a holey amorphous carbon (a-C) substrate, with low energy (2–10 keV/u) H+ and H2+ molecular beams, impinging perpendicularly to the MWCNT axis. The energy distribution of protons traversing the nanotubes (either from the H+ beam or dissociated from the H2+ beam) was measured by the transmission technique in the forward direction. Two well-differentiated peaks appear in the experimental energy-loss distribution of the fragments dissociated from the molecular H2+ beam, in correspondence to the ones detected with the proton beam. One is the low-energy loss peak (LELP), which has a symmetric width; the other is the high-energy loss peak (HELP), which shows an asymmetric broadening towards larger energy loss than the corresponding proton energy distribution. A semi-classical simulation, accounting for the main interaction processes (both elastic and inelastic), of the proton trajectories through the nanotube and the supporting substrate has been done, in order to elucidate the origin of these structures in the energy spectra. Regarding the H+ energy spectrum, the LELP corresponds to projectiles that travel in quasi-channelling motion through the most outer walls of the nanotubes and then pass through the substrate holes, whereas the HELP results mostly from projectiles traversing only the a-C substrate, with the asymmetry broadening being due to a minor contribution of those protons that cross the a-C substrate after exiting the nanotube. The broadening of the peaks corresponding to dissociated fragments, with respect to that of the isolated protons, is the result of vicinage effects between the fragments, when travelling in quasi-channelling conditions through the outer layers of the nanotube, and Coulomb explosion just after exiting the target. The excellent agreement between the measured and the simulated energy spectra of the H+ beam validates our simulation code in order to predict the energy deposited by ion beams in carbon nanotubes.This work has been financially supported by Fondecyt 1100759, Fondecyt 1121203 and USM-DGIP 11.11.11, Anillo ACT1108, Proyecto Basal FB0821 - CONICYT, the Spanish Ministerio de Economía y Competitividad and European Regional Development Fund (Projects FIS2014-58849-P and PGC2018-096788-B-I00), and Fundación Séneca (Project No. 19907/GERM/15)

    Impact assessment of agricultural inputs into a Mediterranean coastal lagoon (Mar Menor, SE)

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    The Mar Menor is a coastal lagoon threatened by the development of intensive agriculture in the surrounding areas. Large amounts of pesticides from these areas are discharged into El Albujón, a permanent watercourse flowing into the lagoon. We have used a multi-biomarker approach to assess the biological effects arising in bivalve species affected by agricultural pollution. Biomarkers indicative of neurotoxicity (acetylcholinesterase, AchE), oxidative stress (catalase, CAT; glutathione reductase, GR and lipid peroxidation, LPO), phase II biotransformation of xenobiotics (glutathione S-transferase, GST) and physiological stress (scope for growth, SFG) were measured in clams transplanted to four sites of the lagoon (two reference sites and two sites affected by the dispersion of the effluent of the El Albujón), for exposure periods of 7 and 22 days. The hazards of this effluent were also examined by simultaneously measuring up to 83 contaminants (pesticides, PCBs, PAHs and others) in samples of fresh water from the watercourse mouth and seawater from the deployed sites, as well as the bioaccumulation of organochlorinated compounds and PAHs in the transplanted animals. Biomarker responses showed marked differences between reference and affected sites after 7 and 22 days. However it was only after 22 days that Principal Component Analysis (PCA) of the biomarker responses distinguished between clams deployed in sites affected by the dispersion of the effluent of the watercourse and those from the reference sites. The chemical analysis of water showed high concentrations of pesticides close to El Albujón watercourse mouth, with the greatest input flux corresponding to the organophosphate chlorpyrifos, followed by pendimethalin and naphthalene, and at lower levels acenaphthene, terbuthylazine-desethyl and chlorpyrifos-methyl. In this regard, PCA analysis showed that the biological effects of the mixture of pesticides in caged clams after 22 days were reduced levels of AchE and SFG and increased levels of GR and phase II GST activity. An Integrated Biomarker Response index was calculated from the combination of these biomarkers, proving useful for the assessment of the impact of agricultural pollution in caged clams.Preprint3,761
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