990 research outputs found

    A Software For Surgical And Radiotherapy Planning Through Multimodal Brain Image Registration And Fusion

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    Naranjo Ornedo, V.; Morales, S.; Legaz-Aparicio, A.; Larrey-Ruiz, J.; Bernabeu, A.; Fuentes-Hurtado, F. (2015). A Software For Surgical And Radiotherapy Planning Through Multimodal Brain Image Registration And Fusion. International Journal of Computer Assisted Radiology and Surgery. 10(Suppl 1):S15-S17. http://hdl.handle.net/10251/65379SS15S1710Suppl

    Lixiviación de nitratos en dos suelos al alterar sus propiedades físicas

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    Se realizaron dos experimentos en los cuales, mediante la mezcla de horizontes A y B o arena y horizontes B, se alteraron los contenidos de materia orgánica en un grupo y arena en otro, en dos suelos diferentes del departamento de Antioquia: un Andisol y un Oxisol, con el propósito de determinar cómo los cambios inducidos artificialmente en estas propiedades afectan la capacidad del suelo para retener nitratos. Los incrementos en el contenido de arena aumentaron significativamente las cantidades de nitrógeno recuperado en columnas de lixiviación, en tanto que las alteraciones en el contenido de materia orgánica sólo afectaron la capacidad para retener nitratos en el Andisol. El experimento permitió identificar los suelos estudiados como altos retenedores de nitratos, no obstante, existen otros factores adicionales a las características estudiadas que no fueron considerados en este experimento, igualmente importantes en la retención del ion.Two experiments in columns were carried out, to study how changes in organic matter and sand content of soil could affect its ability to retain added nitric nitrogen. Mixtures of A and B horizons or quartz sand and B horizon taken from soils belonging to Andisol and Oxisol orders, let us artificially change organic matter and sand content in each soil before a nitrate leaching test. Changes in sand content significantly reduce the ability to retain nitric nitrogen in both soils, and organic matter reduction accounted for a increase in nitrate leaching only in the Andisol. A brief discussion is shown, about the possible role of another conditions influencing nitrate leaching in this soils

    The influence of natural fire and cultural practices on island ecosystems: insights from a 4800 year record from Gran Canaria, Canary Islands

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    Aim: Long-term ecological data provide a stepped frame of island ecosystem transformation after successive waves of human colonization, essential to determine conservation and management baselines. However, the timing and ecological impact of initial human settlement on many islands is still poorly known. Here we report analyses from a 4800-year sedimentary sequence from Gran Canaria (Canary Islands), with the goal of disentangling forest responses to natural fire from early human pressure on the island.Location: La Calderilla, a volcanic maar caldera at 1770 m a.s.l. on Gran Canaria.Taxon: plants and fungi.Methods: A core from the caldera infill was analysed for sediment properties, pollen, micro- and macrocharcoal, with radiocarbon and biochronology dating. Fossil data were statistically zoned and interpreted with the help of cross-correlation and ordination analyses. Surface samples and a pollen–vegetation training set were used as modern analogues for vegetation reconstruction.Results: Before human settlement (4800–2000 cal. yr BP), pine (Pinus canariensis) pollen dominated. Extensive dry pine forests characterised the highlands, although with temporary declining phases, followed by prompt (sub-centennial scale) recovery. Towards 2280 cal. yr BP there was a shift to open vegetation, marked by an increase in coprophilous spores. Coincidental with independent evidence of human settlement in the pine belt (2000–470 cal. yr BP) there was a decline of pine and a peak in charcoal. Following historic settlement (470–0 cal. yr BP), pollen producers from anthropogenic habitats, secondary vegetation and coprophilous fungi increased in abundance, reflecting higher pressure of animal husbandry and farming. Modern moss polsters reflect extensive reforestation since 1950 CE (Common Era).Main conclusions: From 4800 cal. yr BP, the pristine vegetation covering the Gran Canaria highlands was a mosaic of dry pine forests and open vegetation. The pine forests sustained intense fires, which may well have promoted habitat diversity. Human interference was initiated around 2280 cal. yr BP probably by recurrent cultural firing and animal husbandry, triggering a steady trend of forest withdrawal and expansion of grasses and scrubs, until the final disappearance of the pine forest locally in the 20th century. Grasslands were found to be of ancient cultural origin in the summit areas of Gran Canaria, although they underwent an expansion after the Castilian Conquest

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

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    The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO

    Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV

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    Results are presented from a search for physics beyond the standard model based on events with large missing transverse energy, at least three jets, and at least one, two, or three b-quark jets. The study is performed using a sample of proton-proton collision data collected at sqrt(s) = 7 TeV with the CMS detector at the LHC in 2011. The integrated luminosity of the sample is 4.98 inverse femtobarns. The observed number of events is found to be consistent with the standard model expectation, which is evaluated using control samples in the data. The results are used to constrain cross sections for the production of supersymmetric particles decaying to b-quark-enriched final states in the context of simplified model spectra.Comment: Submitted to Physical Review

    CNNs for automatic glaucoma assessment using fundus images: an extensive validation

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    Background Most current algorithms for automatic glaucoma assessment using fundus images rely on handcrafted features based on segmentation, which are affected by the performance of the chosen segmentation method and the extracted features. Among other characteristics, convolutional neural networks (CNNs) are known because of their ability to learn highly discriminative features from raw pixel intensities. Methods In this paper, we employed five different ImageNet-trained models (VGG16, VGG19, InceptionV3, ResNet50 and Xception) for automatic glaucoma assessment using fundus images. Results from an extensive validation using cross-validation and cross-testing strategies were compared with previous works in the literature. Results Using five public databases (1707 images), an average AUC of 0.9605 with a 95% confidence interval of 95.92–97.07%, an average specificity of 0.8580 and an average sensitivity of 0.9346 were obtained after using the Xception architecture, significantly improving the performance of other state-of-the-art works. Moreover, a new clinical database, ACRIMA, has been made publicly available, containing 705 labelled images. It is composed of 396 glaucomatous images and 309 normal images, which means, the largest public database for glaucoma diagnosis. The high specificity and sensitivity obtained from the proposed approach are supported by an extensive validation using not only the cross-validation strategy but also the cross-testing validation on, to the best of the authors’ knowledge, all publicly available glaucoma-labelled databases. Conclusions These results suggest that using ImageNet-trained models is a robust alternative for automatic glaucoma screening system. All images, CNN weights and software used to fine-tune and test the five CNNs are publicly available, which could be used as a testbed for further comparisons

    Amphioxus functional genomics and the origins of vertebrate gene regulation.

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    Vertebrates have greatly elaborated the basic chordate body plan and evolved highly distinctive genomes that have been sculpted by two whole-genome duplications. Here we sequence the genome of the Mediterranean amphioxus (Branchiostoma lanceolatum) and characterize DNA methylation, chromatin accessibility, histone modifications and transcriptomes across multiple developmental stages and adult tissues to investigate the evolution of the regulation of the chordate genome. Comparisons with vertebrates identify an intermediate stage in the evolution of differentially methylated enhancers, and a high conservation of gene expression and its cis-regulatory logic between amphioxus and vertebrates that occurs maximally at an earlier mid-embryonic phylotypic period. We analyse regulatory evolution after whole-genome duplications, and find that-in vertebrates-over 80% of broadly expressed gene families with multiple paralogues derived from whole-genome duplications have members that restricted their ancestral expression, and underwent specialization rather than subfunctionalization. Counter-intuitively, paralogues that restricted their expression increased the complexity of their regulatory landscapes. These data pave the way for a better understanding of the regulatory principles that underlie key vertebrate innovations
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