2,240 research outputs found
Theoretical study of energy transfer in Rb(7S) + Rb(5S) and Rb(5D) + Rb(5S) collisions
No full textWe present results of theoretical studies of the non-resonant excitation transfer
in Rb(7S) + Rb(5S) and Rb(5D) + Rb(5S) collisions at thermal collision energies. Rb2
adiabatic molecular terms correlating with the 5S+7S, 5S+5D and 5P+5P states of separated
atoms were calculated for internuclear distances R > 20 a.u. using asymptotic approximation.
Mechanisms of
collisional population and quenching of the 5D state were treated on the basis of the computed
molecular terms, and the respective cross-sections were calculated. Theoretical cross-sections
are in good agreement with the experimental values at thermal collision energies ( K)
Inversion and Tunability of Van Hove Singularities in VSb ( = K, Rb, and Cs) kagome metals
No full textTo understand the alkali-metal-dependent material properties of recently
discovered VSb ( = K, Rb, and Cs), we conducted a detailed
electronic structure analysis based on first-principles density functional
theory calculations. Contrary to the case of = K and Rb, the energetic
positions of the low-lying Van Hove singularities are reversed in
CsVSb, and the characteristic higher-order Van Hove point gets
closer to the Fermi level. We found that this notable difference can be
attributed to the chemical effect, apart from structural differences. Due to
their different orbital compositions, Van Hove points show qualitatively
different responses to the structure changes. A previously unnoticed highest
lying point can be lowered, locating close to or even below the other ones in
response to a reasonable range of bi- and uni-axial strain. Our results can be
useful in better understanding the material-dependent features reported in this
family and in realizing experimental control of exotic quantum phases.Comment: Physical Chemistry Chemical Physics (PCCP) in pres
Absolute frequency measurements of the lines in and with 0.1 ppb uncertainty
No full textWe report values for the -line frequencies with 0.13 ppb uncertainty in the alkali atoms and The frequencies are measured using an evacuated ringcavity resonator whose length is calibrated against a reference laser locked to the line in The measured frequencies, along with sub-ppb measurement of the atomic masses reported previously, form important links in a possible high-precision determination of the fine-structure constant using the photon-recoil shift measured in an atom interferometer. We also obtain, with improved precision, the hyperfine-coupling constants in the state of these atoms, and the fine-structure interval in the 5P state of Rb
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
Parametric hazard rate models for long-term sickness absence
No full textPURPOSE: In research on the time to onset of sickness absence and the duration of sickness absence episodes, Cox proportional hazard models are in common use. However, parametric models are to be preferred when time in itself is considered as independent variable. This study compares parametric hazard rate models for the onset of long-term sickness absence and return to work. METHOD: Prospective cohort study on sickness absence with four follow-up years of 53,830 employees working in the private sector in the Netherlands. The time to onset of long-term (>6 weeks) sickness absence and return to work were modelled by parametric hazard rate models. RESULTS: The exponential parametric model with a constant hazard rate most accurately described the time to onset of long-term sickness absence. Gompertz-Makeham models with monotonically declining hazard rates best described return to work. CONCLUSIONS: Parametric models offer more possibilities than commonly used models for time-dependent processes as sickness absence and return to work. However, the advantages of parametric models above Cox models apply mainly for return to work and less for onset of long-term sickness absence
Activity-modulating monoclonal antibodies to the human serine protease HtrA3 provide novel insights into regulating HtrA proteolytic activities.
No full textMammalian HtrA (high temperature requirement factor A) proteases, comprising 4 multi-domain members HtrA1-4, play important roles in a number of normal cellular processes as well as pathological conditions such as cancer, arthritis, neurodegenerative diseases and pregnancy disorders. However, how HtrA activities are regulated is not well understood, and to date no inhibitors specific to individual HtrA proteins have been identified. Here we investigated five HtrA3 monoclonal antibodies (mAbs) that we have previously produced, and demonstrated that two of them regulated HtrA3 activity in an opposing fashion: one inhibited while the other stimulated. The inhibitory mAb also blocked HtrA3 activity in trophoblast cells and enhanced migration and invasion, confirming its potential in vivo utility. To understand how the binding of these mAbs modulated HtrA3 protease activity, their epitopes were visualized in relation to a 3-dimensional HtrA3 homology model. This model suggests that the inhibitory HtrA3 mAb blocks substrate access to the protease catalytic site, whereas the stimulatory mAb may bind to the PDZ domain alone or in combination with the N-terminal and protease domains. Since HtrA1, HtrA3 and HtrA4 share identical domain organization, our results establish important foundations for developing potential therapeutics to target these HtrA proteins specifically for the treatment of a number of diseases, including cancer and pregnancy disorders
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
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