2,322 research outputs found

    Multigrid Methods in Lattice Field Computations

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    The multigrid methodology is reviewed. By integrating numerical processes at all scales of a problem, it seeks to perform various computational tasks at a cost that rises as slowly as possible as a function of nn, the number of degrees of freedom in the problem. Current and potential benefits for lattice field computations are outlined. They include: O(n)O(n) solution of Dirac equations; just O(1)O(1) operations in updating the solution (upon any local change of data, including the gauge field); similar efficiency in gauge fixing and updating; O(1)O(1) operations in updating the inverse matrix and in calculating the change in the logarithm of its determinant; O(n)O(n) operations per producing each independent configuration in statistical simulations (eliminating CSD), and, more important, effectively just O(1)O(1) operations per each independent measurement (eliminating the volume factor as well). These potential capabilities have been demonstrated on simple model problems. Extensions to real life are explored.Comment: 4

    Denis Diderot: A Secular Hero

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    My Honors Senior Project is a biography of Denis Diderot in the form of a children\u27s song. MY understanding of Diderot\u27s life is based on Andrew Curran\u27s book, Diderot and the Art of Thinking Freely. Songs help us memorize and retain information about the world, and singing songs together strengthens cultural and religious connections. Secular (nonreligious) people need songs, too. Diderot was a philosopher who didn\u27t believe in God. He was an editor of L\u27Encyclopédie, one of the first encyclopedias, and he snuck in articles that challenged how people think. This was an important moment -- knowledge about the world could belong to everyone, it didn\u27t only come from church or state control. Diderot was known to have many ideas, and to think quickly. He loved to talk and ask questions. Diderot is famous for helping people understand the world in a new way. My song seeks to capture the joyous curiosity that characterized much of Diderot\u27s life

    Multigrid for propagators of staggered fermions in four-dimensional SU(2)SU(2) gauge fields

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    Multigrid (MG) methods for the computation of propagators of staggered fermions in non-Abelian gauge fields are discussed. MG could work in principle in arbitrarily disordered systems. The practical variational MG methods tested so far with a ``Laplacian choice'' for the restriction operator are not competitive with the conjugate gradient algorithm on lattices up to 18418^4. Numerical results are presented for propagators in SU(2)SU(2) gauge fields.Comment: 4 pages, 3 figures (one LaTeX-figure, two figures appended as encapsulated ps files); Contribution to LATTICE '92, requires espcrc2.st

    Some Comments on Multigrid Methods for Computing Propagators

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    I make three conceptual points regarding multigrid methods for computing propagators in lattice gauge theory: 1) The class of operators handled by the algorithm must be stable under coarsening. 2) Problems related by symmetry should have solution methods related by symmetry. 3) It is crucial to distinguish the vector space VV from its dual space VV^*. All the existing algorithms violate one or more of these principles.Comment: 16 pages, LaTeX plus subeqnarray.sty (included at end), NYU-TH-93/07/0

    (S)Pinning down protein interactions by NMR

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    Protein molecules are highly diverse communication platforms and their interaction repertoire stretches from atoms over small molecules such as sugars and lipids to macromolecules. An important route to understanding molecular communication is to quantitatively describe their interactions. These types of analyses determine the amounts and proportions of individual constituents that participate in a reaction as well as their rates of reactions and their thermodynamics. Although many different methods are available, there is currently no single method able to quantitatively capture and describe all types of protein reactions, which can span orders of magnitudes in affinities, reaction rates, and lifetimes of states. As the more versatile technique, solution NMR spectroscopy offers a remarkable catalogue of methods that can be successfully applied to the quantitative as well as qualitative descriptions of protein interactions. In this review we provide an easy‐access approach to NMR for the non‐NMR specialist and describe how and when solution state NMR spectroscopy is the method of choice for addressing protein ligand interaction. We describe very briefly the theoretical background and illustrate simple protein–ligand interactions as well as typical strategies for measuring binding constants using NMR spectroscopy. Finally, this review provides examples of caveats of the method as well as the options to improve the outcome of an NMR analysis of a protein interaction reaction

    Fractional Vector Calculus and Fractional Maxwell's Equations

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    The theory of derivatives and integrals of non-integer order goes back to Leibniz, Liouville, Grunwald, Letnikov and Riemann. The history of fractional vector calculus (FVC) has only 10 years. The main approaches to formulate a FVC, which are used in the physics during the past few years, will be briefly described in this paper. We solve some problems of consistent formulations of FVC by using a fractional generalization of the Fundamental Theorem of Calculus. We define the differential and integral vector operations. The fractional Green's, Stokes' and Gauss's theorems are formulated. The proofs of these theorems are realized for simplest regions. A fractional generalization of exterior differential calculus of differential forms is discussed. Fractional nonlocal Maxwell's equations and the corresponding fractional wave equations are considered.Comment: 42 pages, LaTe

    Onset of efficacy and adverse events during Cenobamate titration period

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    Cenobamate; Drug-resistant epilepsy; SeizuresCenobamato; Epilepsia resistente a los medicamentos; ConvulsionesCenobamat; Epilèpsia resistent a medicaments; ConvulsionsObjectives Cenobamate is an antiseizure medication (ASM) approved in Europe as adjunctive therapy for adults with inadequately controlled focal seizures. This post hoc analysis reports onset of efficacy and characterizes time to onset, duration, and severity of the most common treatment-emergent adverse events (TEAEs) during cenobamate titration. Materials & Methods Adult patients with uncontrolled focal seizures taking 1 to 3 concomitant ASMs were randomized to receive adjunctive cenobamate or placebo (double-blind studies C013 and C017) or cenobamate (open-label study C021). Outcome assessments included efficacy (median percentage change in seizure frequency and onset [studies C013 and C017]) and safety (onset, duration, and severity of TEAEs [all studies]). Results Onset of efficacy was observed by Weeks 1 to 4 of titration in studies C013 and C017 which used a faster titration schedule than study CO21. In study C013, the median percentage seizure frequency reduction was 36.7% in patients receiving cenobamate versus 16.3% in those taking placebo (p = .002); in study C017, significant differences in seizure frequency emerged in Week 1 and continued throughout titration between all cenobamate groups and placebo (p < .001). The most commonly reported TEAEs were somnolence, dizziness, fatigue, and headache, with first onset of each reported as early as Week 1; however, the majority resolved. Conclusions Reductions in seizure frequency occurred during titration with initial efficacy observed prior to reaching the target dose. These reductions were regarded as clinically meaningful because they may indicate early efficacy at lower doses than previously expected and had a considerable impact on patient quality of life. Long-term treatment with adjunctive cenobamate was generally safe and well-tolerated.The double-blind studies and open-label study were funded by SK Life Science, Inc. (Paramus, NJ, USA). Study data were pooled and analyzed by Angelini S.p.a. Nicole Day, PhD, of MedVal Scientific Information Services, LLC (Princeton, NJ, USA) provided medical writing assistance, funded by Angelini S.p.a. The manuscript was prepared according to the International Society for Medical Publication Professionals' “Good Publication Practice for Communicating Company-Sponsored Medical Research: GPP3.

    X-chromosome SNP analyses in 11 human Mediterranean populations show a high overall genetic homogeneity except in North-west Africans (Moroccans)

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    Due to its history, with a high number of migration events, the Mediterranean basin represents a challenging area for population genetic studies. A large number of genetic studies have been carried out in the Mediterranean area using different markers but no consensus has been reached on the genetic landscape of the Mediterranean populations. In order to further investigate the genetics of the human Mediterranean populations, we typed 894 individuals from 11 Mediterranean populations with 25 single-nucleotide polymorphisms (SNPs) located on the X-chromosome. A high overall homogeneity was found among the Mediterranean populations except for the population from Morocco, which seemed to differ genetically from the rest of the populations in the Mediterranean area. A very low genetic distance was found between populations in the Middle East and most of the western part of the Mediterranean Sea.A higher migration rate in females versus males was observed by comparing data from X-chromosome, mt-DNA and Y-chromosome SNPs both in the Mediterranean and a wider geographic area.Multilocus association was observed among the 25 SNPs on the X-chromosome in the populations from Ibiza and Cosenza. Our results support both the hypothesis of (1) a reduced impact of the Neolithic Wave and more recent migration movements in NW-Africa, and (2) the importance of the Strait of Gibraltar as a geographic barrier. In contrast, the high genetic homogeneity observed in the Mediterranean area could be interpreted as the result of the Neolithic wave caused by a large demic diffusion and/or more recent migration events. A differentiated contribution of males and females to the genetic landscape of the Mediterranean area was observed with a higher migration rate in females than in males. A certain level of background linkage disequilibrium in populations in Ibiza and Cosenza could be attributed to their demographic background
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