2,744 research outputs found

    A computer program for plotting stress-strain data from compression, tension, and torsion tests of materials

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    A computer program for plotting stress-strain curves obtained from compression and tension tests on rectangular (flat) specimens and circular-cross-section specimens (rods and tubes) and both stress-strain and torque-twist curves obtained from torsion tests on tubes is presented in detail. The program is written in FORTRAN 4 language for the Control Data 6000 series digital computer with the SCOPE 3.0 operating system and requires approximately 110000 octal locations of core storage. The program has the capability of plotting individual strain-gage outputs and/or the average output of several strain gages and the capability of computing the slope of a straight line which provides a least-squares fit to a specified section of the plotted curve. In addition, the program can compute the slope of the stress-strain curve at any point along the curve. The computer program input and output for three sample problems are presented

    Parameter scaling in the decoherent quantum-classical transition for chaotic systems

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    The quantum to classical transition has been shown to depend on a number of parameters. Key among these are a scale length for the action, \hbar, a measure of the coupling between a system and its environment, DD, and, for chaotic systems, the classical Lyapunov exponent, λ\lambda. We propose computing a measure, reflecting the proximity of quantum and classical evolutions, as a multivariate function of (,λ,D)(\hbar,\lambda,D) and searching for transformations that collapse this hyper-surface into a function of a composite parameter ζ=αλβDγ\zeta = \hbar^{\alpha}\lambda^{\beta}D^{\gamma}. We report results for the quantum Cat Map, showing extremely accurate scaling behavior over a wide range of parameters and suggest that, in general, the technique may be effective in constructing universality classes in this transition.Comment: Submitte

    Coming to America: Multiple Origins of New World Geckos

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    Geckos in the Western Hemisphere provide an excellent model to study faunal assembly at a continental scale. We generated a time-calibrated phylogeny, including exemplars of all New World gecko genera, to produce a biogeographic scenario for the New World geckos. Patterns of New World gecko origins are consistent with almost every biogeographic scenario utilized by a terrestrial vertebrate with different New World lineages showing evidence of vicariance, dispersal via temporary land bridge, overseas dispersal, or anthropogenic introductions. We also recovered a strong relationship between clade age and species diversity, with older New World lineages having more species than more recently arrived lineages. Our data provide the first phylogenetic hypothesis for all New World geckos and highlight the intricate origins and ongoing organization of continental faunas. The phylogenetic and biogeographical hypotheses presented here provide an historical framework to further pursue research on the diversification and assembly of the New World herpetofauna

    Crosstalk and the evolvability of intracellular communication

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    Metazoan signalling networks are complex, with extensive crosstalk between pathways. It is unclear what pressures drove the evolution of this architecture. We explore the hypothesis that crosstalk allows different cell types, each expressing a specific subset of signalling proteins, to activate different outputs when faced with the same inputs, responding differently to the same environment. We find that the pressure to generate diversity leads to the evolution of networks with extensive crosstalk. Using available data, we find that human tissues exhibit higher levels of diversity between cell types than networks with random expression patterns or networks with no crosstalk. We also find that crosstalk and differential expression can influence drug activity: no protein has the same impact on two tissues when inhibited. In addition to providing a possible explanation for the evolution of crosstalk, our work indicates that consideration of cellular context will likely be crucial for targeting signalling networks

    Numerical Methods for the QCD Overlap Operator: I. Sign-Function and Error Bounds

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    The numerical and computational aspects of the overlap formalism in lattice quantum chromodynamics are extremely demanding due to a matrix-vector product that involves the sign function of the hermitian Wilson matrix. In this paper we investigate several methods to compute the product of the matrix sign-function with a vector, in particular Lanczos based methods and partial fraction expansion methods. Our goal is two-fold: we give realistic comparisons between known methods together with novel approaches and we present error bounds which allow to guarantee a given accuracy when terminating the Lanczos method and the multishift-CG solver, applied within the partial fraction expansion methods.Comment: 30 pages, 2 figure

    Failure to Preserve β-Cell Function With Mycophenolate Mofetil and Daclizumab Combined Therapy in Patients With New- Onset Type 1 Diabetes

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    OBJECTIVE This trial tested whether mycophenolate mofetil (MMF) alone or with daclizumab (DZB) could arrest the loss of insulin-producing β-cells in subjects with new-onset type 1 diabetes. RESEARCH DESIGN AND METHODS A multi-center, randomized, placebo-controlled, double-masked trial was initiated by Type 1 Diabetes TrialNet at 13 sites in North America and Europe. Subjects diagnosed with type 1 diabetes and with sufficient C-peptide within 3 months of diagnosis were randomized to either MMF alone, MMF plus DZB, or placebo, and then followed for 2 years. The primary outcome was the geometric mean area under the curve (AUC) C-peptide from the 2-h mixed meal tolerance test. RESULTS One hundred and twenty-six subjects were randomized and treated during the trial. The geometric mean C-peptide AUC at 2 years was unaffected by MMF alone or MMF plus DZB versus placebo. Adverse events were more frequent in the active therapy groups relative to the control group, but not significantly. CONCLUSIONS Neither MMF alone nor MMF in combination with DZB had an effect on the loss of C-peptide in subjects with new-onset type 1 diabetes. Higher doses or more targeted immunotherapies may be needed to affect the autoimmune process

    Fiabot!: design and evaluation of a mobile storytelling application for schools

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    This paper contributes to the ongoing debate about how digital technology can be integrated into the formal education system. Within a longitudinal research study, which lasted four years, we conducted an investigation on how mobile technology can support educational activities as defined by a school curriculum. Among the topics included in the school curriculum, we focused on the literary field and developed a Digital StoryTelling (DST) application, Fiabot!, to support this activity. Here, we describe the design of the application and how we evaluated its impact on educational activities. The application was designed and evaluated in two primary schools. The study had the objectives of exploring whether Fiabot! supports children in achieving educational objectives defined by the curriculum, how this effectively supports teachers, and to what extent children like using it for the creation and sharing of their stories. Our findings show that the application has a positive impact on curriculum enactment and effectively supports the related educational activities. Overall, Fiabot! wasdemonstrated to be very effective in stimulating children's discussion of a story's plot and characters. Thus, Fiabot! supported children not only in being creative but also in organizing their work and exploring a digital media opportunity. This resulted in the development of new skills and the better grounding of previously acquired knowledge, while teachers also had the opportunity to expand their teaching skills and get a taste of ICT's potential in education

    Tumor Heterogeneity as a Predictor of Response to Neoadjuvant Chemotherapy in Locally Advanced Rectal Cancer

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    BACKGROUND: Neoadjuvant chemoradiotherapy (nCRT) is the standard of care for locally advanced adenocarcinoma of the rectum, but it is currently unknown which patients have disease that will respond. This study tested the correlation between response to nCRT and intratumoral heterogeneity using next-generation sequencing assays. PATIENTS AND METHODS: DNA was extracted from formalin-fixed, paraffin-embedded biopsy samples from a cohort of patients with locally advanced rectal adenocarcinoma (T3/4 or N1/2 disease) who received nCRT. High read-depth sequencing of \u3e 400 cancer-relevant genes was performed. Tumor mutations and variant allele frequencies were used to calculate mutant-allele tumor heterogeneity (MATH) scores as measures of intratumoral heterogeneity. Response to nCRT was pathologically scored after surgical resection. RESULTS: Biopsy samples from 21 patient tumors were analyzed. Eight patients had disease noted to have complete response, 2 moderate, 4 minimal, and 7 poor. Higher MATH scores correlated with poorer response to treatment, demonstrating significantly increased tumor heterogeneity compared to complete response (P = .039). CONCLUSION: The application of MATH scores as a measure of tumor heterogeneity may provide a useful biomarker for treatment response in locally advanced rectal cancer
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