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Now showing items 113 - 128 of 148122

  • A characterization of the ball in ?n

    Diederich, K.   Forn?ss, J. E.   Wold, E. F.  

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  • N of 1 randomized trials: A commentary

    Guyatt   Gordon  

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  • A Faber–Krahn Inequality for the Cheeger Constant of $$N$$ N -gons

    Bucur, Dorin   Fragalà, Ilaria  

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  • Homonuclear bond activation using a stable N, N '-diamidocarbene

    Wiggins, Kelly M.   Moerdyk, Jonathan P.   Bielawski, Christopher W.  

    The activation of molecules possessing homonuclear bonds (i.e., X-X, where X Br, O, S, or C) using a stable N, N'-diamidocarbene (DAC) is described. Exposing bromine to the DAC at 25 degrees C afforded a substituted tetrahydropyrimidinium salt in good yield (70%). In contrast, treatment of the DAC with benzoyl peroxide or various disulfides afforded the corresponding diamidoketal or diamidothioketal products, respectively, under mild conditions (25 degrees C) and in good yield (60-80%). Mechanistic and kinetic studies of the latter reactions were consistent with a concerted process involving the nucleophilic attack of the DAC on the aforementioned substrates. While the diamidoketal decomposed to the corresponding urea (91% yield) at 25 degrees C, the diamidothioketals produced a thiolate which induced rearrangement to the corresponding ring-opened thioesters (78-90% yield) at elevated temperatures (60 degrees C). The DAC also inserted into the C(O)-C(O) bond of cyclic and acyclic diones as well as the C(O)-CR bond of a cyclopropenone under mild conditions (25-60 degrees C); the corresponding products were subsequently isolated in good yield (75-90%).
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  • Frederick N. Scatena: A tropical geomorphologist

    Ariel E. Lugo  

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  • Augmented Reality-enhanced Elbow Arthroscopy: N/A - not a clinical study

    Michiro Yamamoto   Takehiro Tawara   Shintaro Oyama   Yukimi Murakami   Hideo Yokota   Hitoshi Hirata  

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  • (C1.04H)n: A nearly perfect pure graphane

    Yang, Yang   Li, Yongjun   Huang, Zhong   Huang, Xiaoyu  

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  • Constructing a Gene Team Tree in Almost O (n lg n) Time.

    Wang, Biing-Feng   Lin, Chien-Hsin   Yang, I-Tse  

    An important model of a conserved gene cluster is called the gene team model, in which a chromosome is defined to be a permutation of distinct genes and a gene team is defined to be a set of genes that appear in two or more species, with the distance between adjacent genes in the team for each chromosome always no more than a certain threshold delta. A gene team tree is a succinct way to represent all gene teams for every possible value of delta. The previous fastest algorithm for constructing a gene team tree of two chromosomes requires O(n lg n lglg n) time, which was given by Wang and Lin. Its bottleneck is a problem called the maximum-gap problem. In this paper, by presenting an improved algorithm for the maximum-gap problem, we reduce the upper bound of the gene team tree problem to O(n lg n alpha(n)). Since alpha grows extremely slowly, this result is almost as efficient as the current best upper bound, O(n lg n), for finding the gene teams of a fixed delta value. Our new algorithm is very efficient from both the theoretical and practical points of view. Wang and Lin's gene-team-tree algorithm can be extended to k chromosomes with complexity O(kn lg n lglg n). Similarly, our improved algorithm for the maximum-gap problem reduces this running time to O(kn lg n alpha(n)). In addition, it also provides new upper bounds for the gene team tree problem on general sequences, in which multiple copies of the same gene are allowed. =20
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  • On a Conjecture of Cusick Concerning the Sum of Digits of $n$ and $n+t$

    Drmota, Michael; Kauers, Manuel; Spiegelhofer, Lukas  

    For a nonnegative integer t, let e(t) be the asymptotic density of natural numbers n for which s(n + t) >=3D s(n), where s(n()) denotes the sum of digits of n in base 2. We prove that e(t) > 1/2 for t in a set of asymptotic density 1, thus giving a partial solution to a conjecture of Cusick stating that e(t) > 1/2 for all t. Interestingly, this problem has several equivalent formulations, for example that the polynomial X(X + 1) ... (X + t - 1) has less than 2(t) zeros modulo 2(t+1). The proof of the main result is based on Chebyshev's inequality and the asymptotic analysis of a trivariate rational function using methods from analytic combinatorics.
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  • Enantioselective Total Synthesis of Altersolanol A and N

    Mechsner, Bastian   Böse, Dietrich   Hogenkamp, Fabian   Ledermann, Nadia   Hartmann, Rudolf   Bochinsky, Kevin   Frey, Wolfgang   Pietruszka, Jörg  

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  • N° 372 - Déclaration sur l'accouchement à domicile planifié

    Campbell, Kim   Carson, George   Azzam, Hussam   Hutton, Eileen  

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  • Uplifting GPPZ: a ten-dimensional dual of N=1∗$$ \mathcal{N}={1}^{\ast } $$

    Bobev, Nikolay   Gautason, Friðrik Freyr   Niehoff, Benjamin E.   van Muiden, Jesse  

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  • ’n Poëtiese fotoboek

    Taljard, Marlies  

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  • Can a nn Resonance Constrain the n Amplitude?

    Afnan, Iraj R.   Gibson, Benjamin F.  

    We address the question of constraints on the n amplitude as a result of observing a nn resonance above the nn three-body threshold. To examine this question, we will first demonstrate that by starting with a n interaction based upon the experimental p data and then scaling the n potential by approximate to 8% one can generate a nn resonance, and with a sufficiently large scaling one can generate a nn bound state. This is achieved using the three-body Faddeev equations with rank one separable potentials for all pairwise interactions. The use of separable potentials is motivated by two factors: (i) the Faddeev equations reduce to a set of one dimensional integral equations that can be analytically continued into the complex energy plane where resonances reside. (ii) The n amplitude can be defined in terms of the effective range parameters. As a result we can explore the question: What constraint can be placed on the n effective range parameters by the nn resonance parameters?
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  • A first-principles study of NinPdn (n=3D1-5) clusters

    Cervantes-Flores, Aldo   Cruz-Martinez, Heriberto   Solorza-Feria, Omar   Calaminici, Patrizia  

    A first-principle investigation of structures and properties of NinPdn (n =3D 1-5) clusters is presented. For this study, the linear combination of Gaussian-type orbitals auxiliary density functional theory (LCGTO-ADFT) method has been employed. In order to determine the lowest energy structures, several isomers in different spin multiplicities were studied, for each cluster size. Initial structures, for which successive geometry optimization was computed without any constrain, were taken along Born-Oppenheimer molecular dynamics (BOMD) trajectories. To discriminate between minima and transition state structures, harmonic frequency analyses were performed at the optimized structures. Ground state structures, bond lengths, harmonic frequencies, dissociation energy, ionization potential, electron affinity and spin density plots are presented. This work demonstrates, that the Pd atoms prefer to allocate on the surface of the cluster structures whose core is formed by the 3d TM atoms type. Moreover, it has been observed that the ground-state structure spin multiplicity increases as the system size grows. The results of this study contribute to gain insight into how structures and energy properties change with cluster size in bimetallic Pd-based alloys.
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  • Interview With Marilyn Monk, BSc, MSc(A)N

    Roxane Spitzer  

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