4,735 research outputs found

    A quinazoline-based HDAC inhibitor affects gene expression pathways involved in cholesterol biosynthesis and mevalonate in prostate cancer cells

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    Chronic inflammation can lead to the development of cancers and resolution of inflammation is an ongoing challenge.</p

    Absorption spectrum in the wings of the potassium second resonance doublet broadened by helium

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    We have measured the reduced absorption coefficients occurring in the wings of the potassium 4S-5P doublet lines at 404.414 nm and at 404.720 nm broadened by helium gas at pressures of several hundred Torr. At the experimental temperature of 900 K, we have detected a shoulder-like broadening feature on the blue wing of the doublet which is relatively flat between 401.8 nm and 402.8 nm and which drops off rapidly for shorter wavelengths, corresponding to absorption from the X doublet Sigma+ state to the C doublet Sigma+ state of the K-He quasimolecule. The accurate measurements of the line profiles in the present work will sharply constrain future calculations of potential energy surfaces and transition dipole moments correlating to the asymptotes He-K(5p), He-K(5s), and He-K(3d).Comment: 2 figure

    Probing the Sensitivity of Electron Wave Interference to Disorder-Induced Scattering in Solid-State Devices

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    The study of electron motion in semiconductor billiards has elucidated our understanding of quantum interference and quantum chaos. The central assumption is that ionized donors generate only minor perturbations to the electron trajectories, which are determined by scattering from billiard walls. We use magnetoconductance fluctuations as a probe of the quantum interference and show that these fluctuations change radically when the scattering landscape is modified by thermally-induced charge displacement between donor sites. Our results challenge the accepted understanding of quantum interference effects in nanostructures.Comment: 8 pages, 5 figures, Submitted to Physical Review

    Structure and mechanism of acetolactate decarboxylase

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    Acetolactate decarboxylase catalyzes the conversion of both enantiomers of acetolactate to the (R)-enantiomer of acetoin, via a mechanism that has been shown to involve a prior rearrangement of the non-natural (R)-enantiomer substrate to the natural (S)-enantiomer. In this paper, a series of crystal structures of ALDC complex with designed transition state mimics are reported. These structures, coupled with inhibition studies and site-directed mutagenesis provide an improved understanding of the molecular processes involved in the stereoselective decarboxylation/protonation events. A mechanism for the transformation of each enantiomer of acetolactate is proposed

    The composite first person narrative: Texture, structure, and meaning in writing phenomenological descriptions

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    This paper illustrates the use of composite first person narrative interpretive methods, as described by Todres, across a range of phenomena. This methodology introduces texture into the presently understood structures of phenomena and thereby creates new understandings of the phenomenon, bringing about a form of understanding that is relationally alive that contributes to improved caring practices. The method is influenced by the work of Gendlin, Heidegger, van Manen, Gadamer, and Merleau-Ponty. The method's applicability to different research topics is demonstrated through the composite narratives of nursing students learning nursing practice in an accelerated and condensed program, obese female adolescents attempting weight control, chronically ill male parolees, and midlife women experiencing distress during menopause. Within current research, these four phenomena have been predominantly described and understood through quantified articulations that give the reader a structural understanding of the phenomena, but the more embodied or “contextual” human qualities of the phenomena are often not visible. The “what is it like” or the “unsaid” aspects of such human phenomena are not clear to the reader when proxies are used to “account for” a variety of situated conditions. This novel method is employed to re-present narrative data and findings from research through first person accounts that blend the voices of the participants with those of the researcher, emphasizing the connectedness, the “we” among all participants, researchers, and listeners. These re-presentations allow readers to develop more embodied understandings of both the texture and structure of each of the phenomena and illustrate the use of the composite account as a way for researchers to better understand and convey the wholeness of the experience of any phenomenon under inquiry

    Minkowski Tensors of Anisotropic Spatial Structure

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    This article describes the theoretical foundation of and explicit algorithms for a novel approach to morphology and anisotropy analysis of complex spatial structure using tensor-valued Minkowski functionals, the so-called Minkowski tensors. Minkowski tensors are generalisations of the well-known scalar Minkowski functionals and are explicitly sensitive to anisotropic aspects of morphology, relevant for example for elastic moduli or permeability of microstructured materials. Here we derive explicit linear-time algorithms to compute these tensorial measures for three-dimensional shapes. These apply to representations of any object that can be represented by a triangulation of its bounding surface; their application is illustrated for the polyhedral Voronoi cellular complexes of jammed sphere configurations, and for triangulations of a biopolymer fibre network obtained by confocal microscopy. The article further bridges the substantial notational and conceptual gap between the different but equivalent approaches to scalar or tensorial Minkowski functionals in mathematics and in physics, hence making the mathematical measure theoretic method more readily accessible for future application in the physical sciences

    Quasielastic K-nucleus scattering

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    Quasielastic K^+ - nucleus scattering data at q=290, 390 and 480 MeV/c are analyzed in a finite nucleus continuum random phase approximation framework, using a density-dependent particle-hole interaction. The reaction mechanism is consistently treated according to Glauber theory, keeping up to two-step inelastic processes. A good description of the data is achieved, also providing a useful constraint on the strength of the effective particle-hole interaction in the scalar-isoscalar channel at intermediate momentum transfers. We find no evidence for the increase in the effective number of nucleons participating in the reaction which has been reported in the literature.Comment: 21 pages, uses REVTeX and epsfig, 9 postscript figures; replaced version corrects a few minor errors in the tex

    Superrelativity as a unification of quantum theory and relativity(II)

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    A underlying dynamical structure for both relativity and quantum theory-``superrelativity'' has been proposed in order to overcome the well known incompatibility between these theories. The relationship between curvature of spacetime (gravity) and curvature of the projective Hilbert space of pure quantum states is established as well.Comment: 6 pages,LaTeX,In the Abstract ``proposed on order'' should be read as ``proposed in order'

    Evidence of the Purely Leptonic Decay B- --> tau- nu_tau-bar

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    We present the first evidence of the decay B- --> tau- nu_tau-bar using 414 fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics, and measure the branching fraction to be Br(B- --> tau- nu_tau-bar) = (1.79 +0.56-0.49(stat) +0.46-0.51(syst))*10^-4. This implies that f_B = 0.229 +0.036-0.031(stat) +0.034-0.037(syst) GeV and is the first direct measurement of this quantity.Comment: 6 pages, 3 figures, to appear in Physical Review Letter
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