1,731 research outputs found
Liquid structure of Rb-Hg alloys studied by neutron diffraction
No full textThe structures of liquid Rb–Hg alloys were studied as a function of composition by neutron diffraction. In the intermediate Rb concentration range, the obtained structure factors show a small prepeak, which may be an evidence of the formation of Hg polyanion units in liquids. The Reverse Monte Carlo (RMC) analysis was applied to separate the total radial distribution function into the corresponding partial radial distribution functions. Up to 10 at.% Rb, no obvious changes are found for the first peak position of the partial radial distribution functions of the Hg–Hg pair and that of the Hg–Rb pair. The first peak position between the Hg–Rb pairs increases above 20 at.% Rb. In addition to the first peak, a subpeak between Hg–Hg pairs can be seen in the large distance. At 60 at.% Rb, the nearest neighbor distance between Hg atoms shows the closest value in the concentration range studied. These results indicate that with the progress of charge transfer the solvation structure in the dilute Rb concentration range changes into the structure containing polyanions composed of Hg species
Fractional Edge Cover Number of Model RB
No full textModel RB is a random constraint satisfaction problem with a growing domain size, which exhibits exact phase transition phenomena. Many hard instances with planted solutions can be generated via Model RB, to be used as benchmarks for algorithmic competitions and researches. In the past, some structural parameters of constraint hypergraphs are analyzed to show hardness of Model RB, such as hinge width, decycling number, treewidth, and hypertree width. In this paper, one more structural parameter of constraint hypergraphs of Model RB, namely the fractional edge cover number, is analyzed. We show upper and lower bounds on the fractional edge cover number of Model RB. In particular, the fractional edge cover number of Model RB is shown to be asymptotically linear in the number of variables, like hinge width, decycling number, treewidth and hypertree width. These results together provide further evidences on the hardness of Model RB.EICPCI-S(ISTP)[email protected]
MILLIMETER-WAVE SPECTROSCOPY OF COLD RB ATOMS
No full textAuthor Institution: Department of Physics, University of Virginia, McCormick Road, Charlottesville, Virginia 22903Cold Rb atoms were prepared by magneto-optical trap. Millimeter-wave has been used to drive nd to (n-2)f one-photon and nd to (n-1)g () two-photon transitions. Quantum defects of f and g states of Rb were calculated. Full analyses will be presented. }
Interpretation and the Problem of the Intention of the Author, by Burhanetir Tatar
No full textBurhanetir Tatar, Interpretation and the Problem of the Intention of the Author: H.G. Gadamer vs E.D. Hirsh, The Council for Research in Values and Philosophy, 199
Aneuploidy in spermatids of Robertsonian (Rb) chromosome heterozygous mice
No full text© 2014, The Author(s). Rb translocations are chromosomal rearrangements frequently found in natural populations of the house mouse Mus musculus domesticus. The standard diploid karyotype of the house mouse consisting of 40 telocentric chromosomes may be reduced by the emergence of metacentric Rb chromosomes. Multiple simple Rb heterozygotes form trivalents exhibiting higher anaphase nondisjunction frequency and consequently higher number of unbalanced gametes than in normal males. This work will attempt to establish whether frequencies of aneuploidy observed in heterozygote spermatids of the house mouse M. musculus domesticus show differences in chromosomes derived from different trivalents. Towards this goal, the number and distribution frequency of aneuploidy was assessed via FISH staining of specific chromosomes of spermatids derived from 2n = 32 individuals. Our results showed that for a given set of target chromosomes, 90 % of the gametes were balanced, resulting from alternate s
Synthesis and Characterization of Multiple-Cation Rb(MAFA)PbI3 Perovskite Single Crystals
No full textWe synthesized multiple-cation Rb(MAFA)PbI3 perovskite single crystals for the first time. The effect of Rb+ substitution was systemically investigated, and the addition of 1.5 M 5% RbI was the optimum condition to obtain high-quality Rb(MAFA)PbI3 single crystals. Lattice shrinkage occurred in the Rb(MAFA)PbI3 single crystal because of the small ionic radius of Rb+, resulting in blue-shifted absorption and photoluminescence (PL) peaks. The 1.5 M 5% RbI-added (MAFA)PbI3 single crystal showed the longest carrier lifetime of 18.35 ns, exhibiting the highest photoresponse than other crystals. We believe that this work will provide a basic insight into the mixed-cation perovskite single crystals for the future optoelectronic applications. © The Author(s) 201
TEMPERATURE DEPENDENCE OF AND (n=3-5) CLUSTER IONS
No full textAuthor Institution: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801Competition between ionwater electrostatic interactions and waterwater hydrogen bonding allows several structural isomers of hydrated rubidium cluster ions to exist simultaneously. The cluster ion temperature plays a large role in determining which of these non-covalent interactions will dominate. Colder temperatures favor isomers with multiple hydrogen bonds while warmer temperatures favor less-structured isomers with fewer hydrogen bonds. The temperature, or internal energy, of hydrated rubidium cluster ions is controlled by varying the evaporative path available for cluster formation. If the evaporation involves loss of water molecules, the final cluster ion temperature will be in the range of . Evaporation of argon atoms generates substantially colder cluster ions with temperatures of . Infrared photodissociation spectra of are compared with \textit{(n=3-5)} spectra to illustrate entropic effects on the relative abundance of structural isomers in clusters. The identification of isomers present is aided by parallel \textit{ab initio}, RRKM-EE and thermodynamics calculations
Lagrangian analysis of turbulent rotating convection
No full textThis study aims to explore how the flow transition from one state to the other in rotating convection will affect the Lagrangian statistics of (fluid) particles. 3D Particle Tracking Velocimetry (3D-PTV) is employed in a water-filled cylindrical tank of equal height and diameter 200 mm. The measurements are performed in the central volume of 50 × 50 × 50 mm3 at a Rayleigh number Ra = 1.28 × 109 and Prandtl number Pr = 6.7. We are reporting the velocity and acceleration pdfs for different Rossby numbers. For different rotation rates, the transverse velocity pdfs show a Gaussian distribution. The vertical velocity pdf has slightly wider tails for stationary and high rotation rate cases, while it approaches the Gaussian distribution for intermediate rotation rates. The acceleration pdfs have significantly wider tails in comparison to those of a Gaussian distribution which is similar to the other turbulent flows. Increasing rotation results in less intermittency in vertical acceleration in the center of RB
Direct numerical simulation of open-channel flow in the fully rough regime
No full textThe Direct Numerical Simulation (DNS) of an incompressible open channel flow over a layer of rigid spherical roughness elements fixed on the wall in well-packed square arrangement has been performed which shows values of the Reynolds number Rb ~ 6900 (ks+ ~ 100) and produces a mean velocity defect ∆U+ ~ 7 in the range of the fully-rough regime. First and second moment statistics of the velocity field have been analyzed. The stress distribution as well as the hydrodynamic force and torque acting on the surface of individual roughness elements have been computed. Results are presently shown and compared with those obtained in the context of a previous DNS performed in the transitionally rough regime
Regulation of differentiation-specific genes by the Drosophila RB, E2F, and Myb-interacting proteins complex (dREAM)
No full textRB and E2F proteins play important roles in the regulation of cell division, cell death and development, by controlling the expression of genes involved in these processes. The mechanisms of repression by pRB have been extensively studied at cell cycle regulated promoters. However, little is known about developmentally regulated E2F/RB genes. Here I have taken advantage of the simplicity of the E2F/RB pathway in flies, and inspected the regulation of differentiation-specific target genes. These genes are repressed by dE2F2/RBF and a recently identified RB-containing complex, dREAM, in a cell type- and cell cycle-independent manner. Two different types of activities are involved in their regulation. First, I find that dREAM employs histone deacetylase (HDAC) activities at promoter regions and that HDACs are required to maintain repression. Second, I find that the Polycomb Group (PcG) protein, Enhancer of zeste - E(Z), is involved in silencing of these genes through the di-methylation of histone H3 Lys27 at nucleosomes located downstream of the transcription start sites (TSS). While HDAC activity is also involved in the regulation of cell cycle dependent E2F transcription, E(Z) functions at differentiation-specific target genes only, indicating that the two groups of genes are regulated in a distinct manner. The differentiation-specific genes are also regulated differently from cell cycle-related E2F targets, in a way that they do not depend on E2F-activation. E2F/RB repression is maintained throughout the cell cycle. I demonstrated that the dREAM complex is required for dE2F2 binding at differentiation-specific, but not cell cycle-regulated E2F/RB target gene promoters. Especially, dREAM complex is necessary for dE2F2/RBF binding in S-phase. Taking together, my results demonstrate that dREAM plays a dual role in the regulation of differentiation-specific genes. dREAM complex is required for the stability of dE2F2/RBF complexes at these promoters during S-phase, and also for the repression mechanisms employed at these genes.Ph. D.Includes bibliographical referencesIncludes vitaby Hangnoh Le
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