4,337 research outputs found

    A preliminary review of organic materials single crystal growth by the Czochralski technique

    Get PDF
    The growth of single crystals of organic compounds by the Czochralski method is reviewed. From the literature it is found that single crystals of benzil, a nonlinear optical material with a d sub 11 value of 11.2 + or - 1.5 x d sub 11 value of alpha quartz, has fewer dislocations than generally contained in Bridgman crystals. More perfect crystals were grown by repeated Czochralski growth. This consists of etching away the defect-containing portion of a Czochralski grown crystal and using it as a seed for further growth. Other compounds used to grow single crystals are benzophenone, 12-tricosanone (laurone), and salol. The physical properties, growth apparatus, and processing conditions presented in the literature are discussed. Moreover, some of the possible advantages of growing single crystals of organic compounds in microgravity to obtain more perfect crystals than on Earth are reviewed

    Satellite applications to marine geodesy

    Get PDF
    Potential use of satellites for enhancing positioning capabilities and for marine geodetic contro

    Bayesian optimization for materials design

    Full text link
    We introduce Bayesian optimization, a technique developed for optimizing time-consuming engineering simulations and for fitting machine learning models on large datasets. Bayesian optimization guides the choice of experiments during materials design and discovery to find good material designs in as few experiments as possible. We focus on the case when materials designs are parameterized by a low-dimensional vector. Bayesian optimization is built on a statistical technique called Gaussian process regression, which allows predicting the performance of a new design based on previously tested designs. After providing a detailed introduction to Gaussian process regression, we introduce two Bayesian optimization methods: expected improvement, for design problems with noise-free evaluations; and the knowledge-gradient method, which generalizes expected improvement and may be used in design problems with noisy evaluations. Both methods are derived using a value-of-information analysis, and enjoy one-step Bayes-optimality

    Isolation of high molecular weight DNA from Neurospora

    Get PDF
    Isolation of high molecular weight DNA from Neurospor

    The Limits of Citizenship: Rights of Prisoners and ex-Prisoners in USA

    Get PDF
    Contrary to popular beliefs and commonly held rhetoric, rights are not naturally given to people/residents/citizens. Very few, if any, rights are inherently granted by virtue of being born a human being. Although the authors of the Bill of Rights (in the USA) as well as the United Nations Declaration of Human Rights want us to believe that these rights are innate, in fact they were fought for and only barely achieved. At any given time, there are counter forces that actively push to minimize and reverse rights that were gained after long and hard struggles. For example, in the United States the “sacred” right for privacy was vastly violated with the signature and support of President George W. Bush soon after the attack of September 11, 2001 was carried out within the boundaries of the country. This is but one example where rights are not guaranteed forever and are only in place so long as there are enough people actively fighting to keep them and, if possible, to expand them. My argument, though my data are mostly US-based, is that the rights of prisoners and ex-prisoners are an excellent measure and estimate for the strength of human rights in a given society. The more punitive and exclusionary are the policies towards prisoners and ex-prisoners, the less protected are the rights of citizens in general. The more a society excludes prisoners and ex-prisoners, the more ready it is to limit the rights of other members of that society. I would welcome a comparative study of this topic to assess which societies treat prisoners and ex-prisoners more humanly and which in a more exclusionary manner

    Investigating the veracity of self-reported post-traumatic growth: a profile analysis approach

    Get PDF
    Research into posttraumatic growth—positive psychological change that people report in their relationships, priorities in life, and self-perception after experiences of adversity—has been severely critiqued. We investigated the degree to which community members’ friends and relatives corroborated targets’ self-perceived positive and negative changes as measured by the Posttraumatic Growth Inventory-42. We found corroboration only for negative changes when we examined overall (averaged) scores. However, using a profile analysis procedure, we found significant participant–informant agreement on the domains of change that had relatively higher scores in the target’s profile and those that had relatively lower scores. Our results demonstrate that informants were able to observe that targets had changed and were sensitive to the idiosyncratic ways in which these changes had manifested in targets’ behavior

    Continuous Wavelets on Compact Manifolds

    Full text link
    Let M\bf M be a smooth compact oriented Riemannian manifold, and let ΔM\Delta_{\bf M} be the Laplace-Beltrami operator on M{\bf M}. Say 0 \neq f \in \mathcal{S}(\RR^+), and that f(0)=0f(0) = 0. For t>0t > 0, let Kt(x,y)K_t(x,y) denote the kernel of f(t2ΔM)f(t^2 \Delta_{\bf M}). We show that KtK_t is well-localized near the diagonal, in the sense that it satisfies estimates akin to those satisfied by the kernel of the convolution operator f(t2Δ)f(t^2\Delta) on \RR^n. We define continuous S{\cal S}-wavelets on M{\bf M}, in such a manner that Kt(x,y)K_t(x,y) satisfies this definition, because of its localization near the diagonal. Continuous S{\cal S}-wavelets on M{\bf M} are analogous to continuous wavelets on \RR^n in \mathcal{S}(\RR^n). In particular, we are able to characterize the Ho¨\ddot{o}lder continuous functions on M{\bf M} by the size of their continuous S{\mathcal{S}}-wavelet transforms, for Ho¨\ddot{o}lder exponents strictly between 0 and 1. If M\bf M is the torus \TT^2 or the sphere S2S^2, and f(s)=sesf(s)=se^{-s} (the ``Mexican hat'' situation), we obtain two explicit approximate formulas for KtK_t, one to be used when tt is large, and one to be used when tt is small

    Investigating Potential Biomarkers in Autism Spectrum Disorder

    Get PDF
    Background: Early identification and treatment of individuals with autism spectrum disorder (ASD) improves outcomes, but specific evidence needed to individualize treatment recommendations is lacking. Biomarkers that could be routinely measured within the clinical setting could potentially transform clinical care for patients with ASD. This demonstration project employed collection of biomarker data during regular autism specialty clinical visits and explored the relationship of biomarkers with clinical ASD symptoms. Methods: Eighty-three children with ASD, aged 5-10 years, completed a multi-site feasibility study integrating the collection of biochemical (blood serotonin, urine melatonin sulfate excretion) and clinical (head circumference, dysmorphology exam, digit ratio, cognitive and behavioral function) biomarkers during routine ASD clinic visits. Parents completed a demographic survey and the Aberrant Behavior Checklist-Community. Cognitive function was determined by record review. Data analysis utilized Wilcoxon two-sample tests and Spearman correlations. Results: Participants were 82% male, 63% White, 19% Hispanic, with a broad range of functioning. Group means indicated hyperserotonemia. In a single regression analysis adjusting for race and median household income, higher income was associated with higher levels of blood serotonin and urine melatonin sulfate excretion levels (p = 0.004 and p = 0.04, respectively). Melatonin correlated negatively with age (p = 0.048) and reported neurologic problems (p = 0.02). Dysmorphic status correlated with higher reported stereotyped behavior (p = 0.02) and inappropriate speech (p = 0.04). Conclusion: This demonstration project employed collection of multiple biomarkers, allowed for examination of associations between biochemical and clinical measures, and identified several findings that suggest direction for future studies. This clinical research model has promise for integrative biomarker research in individuals with complex, heterogeneous neurodevelopmental disorders such as ASD
    corecore