43 research outputs found

    Smolyak's algorithm: A powerful black box for the acceleration of scientific computations

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    We provide a general discussion of Smolyak's algorithm for the acceleration of scientific computations. The algorithm first appeared in Smolyak's work on multidimensional integration and interpolation. Since then, it has been generalized in multiple directions and has been associated with the keywords: sparse grids, hyperbolic cross approximation, combination technique, and multilevel methods. Variants of Smolyak's algorithm have been employed in the computation of high-dimensional integrals in finance, chemistry, and physics, in the numerical solution of partial and stochastic differential equations, and in uncertainty quantification. Motivated by this broad and ever-increasing range of applications, we describe a general framework that summarizes fundamental results and assumptions in a concise application-independent manner

    Hot new directions for quasi-Monte Carlo research in step with applications

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    This article provides an overview of some interfaces between the theory of quasi-Monte Carlo (QMC) methods and applications. We summarize three QMC theoretical settings: first order QMC methods in the unit cube [0,1]s[0,1]^s and in Rs\mathbb{R}^s, and higher order QMC methods in the unit cube. One important feature is that their error bounds can be independent of the dimension ss under appropriate conditions on the function spaces. Another important feature is that good parameters for these QMC methods can be obtained by fast efficient algorithms even when ss is large. We outline three different applications and explain how they can tap into the different QMC theory. We also discuss three cost saving strategies that can be combined with QMC in these applications. Many of these recent QMC theory and methods are developed not in isolation, but in close connection with applications

    The applicability of genetically modified microorganisms in bioremediation of contaminated environments

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    Inżynieria genetyczna, będąca nowoczesną technologią, pozwala na projektowanie mikroorganizmów zdolnych do rozkładu określonego typu zanieczyszczeń. Konstruowanie GMMs na potrzeby bioremediacji jest możliwe dzięki poznaniu mechanizmów degradacji związków toksycznych, szlaków metabolicznych, enzymów katabolicznych oraz odpowiednich genów. Do detekcji i wizualizacji GMMs w środowisku służą różne metody molekularne: FISH, in situ PCR, DGGE, TGGE, T-RFLP, ARDRA oraz markery selekcyjne (lux, gfp, lacZ, xylE). W celu zminimalizowania ryzyka wynikającego z uwolnienia GMMs do środowiska stosowane są pewne bariery genetyczne. Mają one na celu ograniczenie przeżywalności rekombinantów oraz transferu genów do mikroorganizmów autochtonicznych. W artykule omówiono zasady projektowania GMMs oraz przedstawiono przykłady ich praktycznego wykorzystania w bioremediacji zanieczyszczonych środowisk.Genetic engineering is a modern technology, which Allowi to design microorganisms capable of degrading specific contaminants. The construction of GMMs for bioremediation purposes is possible because many degradative pathways, enzyme and their respective genes are known and biochemical reactions are well understood. For selection and identification of GMMs in the environment many molecular techniques were developed. They include FISH, in situ PCR, DGGE, TGGE, T-RFLP, ARDRA and marker genes (lux, gfp, lacZ, xylE). In order to reduce potential risk of the use of GMMs in the environment some genetic barriers were created. They limit survival of the recombinants and gene transfer into autochthonous microorganisms. In this review the construction and practical applications of GMMs in bioremediation studies are discussed
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