375 research outputs found

    Late Bronze Age Hoard studied by PIXE

    Get PDF
    The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising 4 socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production

    Kinematics of electrons near a Van Hove singularity

    Full text link
    A two dimensional electronic system, where the Fermi surface is close to a Van Hove singularity, shows a variety of weak coupling instabilities, and it is a convenient model to study the interplay between antiferromagnetism and anisotropic superconductivity. We present a detailed analysis of the kinematics of the electron scattering in this model. The similitudes, and differences, between a standard Renormalization Group approach and previous work based on parquet summations of log2^2 divergences are analyzed, with emphasis on the underlying physical processes. General properties of the phase diagram are discussed.Comment: 5 pages, 3 postscript figure

    Clinical, Pathological, and Surgical Outcomes for Adult Pineoblastomas

    Get PDF
    Introduction Pineoblastomas are uncommon primitive neuroectodermal tumors that occur mostly in children; they are exceedingly rare in adults. Few published reports have compared the various aspects of these tumors between adults and children. Methods The authors report a series of 12 pineoblastomas in adults from 2 institutions over 24 years. The clinical, radiologic, and pathologic features and clinical outcomes were compared with previously reported cases in children and adults. Results Patient age ranged from 24 to 81 years, and all but 1 patient exhibited symptoms of obstructive hydrocephalus. Three patients underwent gross total resection, and subtotal resection was performed in 3 patients. Diagnostic biopsy specimens were obtained in an additional 6 patients. Pathologically, the tumors had the classical morphologic and immunohistochemical features of pineoblastomas. Postoperatively, 10 patients received radiotherapy, and 5 patients received chemotherapy. Compared with previously reported cases, several differences were noted in clinical outcomes. Of the 12 patients, only 5 (42%) died of their disease (average length of survival, 118 months); 5 patients (42%) are alive with no evidence of disease (average length of follow-up, 92 months). One patient died of unrelated causes, and one was lost to follow-up. Patients with subtotal resections or diagnostic biopsies did not suffer a worse prognosis. Of the 9 patients with biopsy or subtotal resection, 4 are alive, 4 died of their disease, and 1 died of an unrelated hemorrhagic cerebral infarction. Conclusions Although this series is small, the data suggest that pineoblastomas in adults have a less aggressive clinical course than in children

    The Tatton-Brown-Rahman Syndrome: A clinical study of 55 individuals with de novo constitutive DNMT3A variants.

    Get PDF
    Tatton-Brown-Rahman syndrome (TBRS; OMIM 615879), also known as the DNMT3A-overgrowth syndrome, is an overgrowth intellectual disability syndrome first described in 2014 with a report of 13 individuals with constitutive heterozygous DNMT3A variants. Here we have undertaken a detailed clinical study of 55 individuals with de novoDNMT3A variants, including the 13 previously reported individuals. An intellectual disability and overgrowth were reported in >80% of individuals with TBRS and were designated major clinical associations. Additional frequent clinical associations (reported in 20-80% individuals) included an evolving facial appearance with low-set, heavy, horizontal eyebrows and prominent upper central incisors; joint hypermobility (74%); obesity (weight ³2SD, 67%); hypotonia (54%); behavioural/psychiatric issues (most frequently autistic spectrum disorder, 51%); kyphoscoliosis (33%) and afebrile seizures (22%). One individual was diagnosed with acute myeloid leukaemia in teenage years. Based upon the results from this study, we present our current management for individuals with TBRS

    Stochastic Simulations Of Calcium Contents In Sugarcane Area

    Get PDF
    The aim of this study was to quantify and to map the spatial distribution and uncertainty of soil calcium (Ca) content in a sugarcane area by sequential Gaussian and simulated-annealing simulation methods. The study was conducted in the municipality of Guariba, northeast of the Sao Paulo state. A sampling grid with 206 points separated by a distance of 50 m was established, totaling approximately 42 ha. The calcium contents were evaluated in layer of 0-0.20 m. Techniques of geostatistical estimation, ordinary kriging and stochastic simulations were used. The technique of ordinary kriging does not reproduce satisfactorily the global statistics of the Ca contents. The use of simulation techniques allows reproducing the spatial variability pattern of Ca contents. The techniques of sequential Gaussian simulation and simulated annealing showed significant variations in the contents of Ca in the small scale.19876777
    corecore