1,694 research outputs found

    THE EFFECT OF SOLAR RADIATION PRESSURE ON THE SPIN OF EXPLORER XII

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    Solar radiation pressure effect on explorer xii rotatio

    Altered Microviscosity at Brain Membrane Surface Induces Distinct and Reversible Inhibition of Opioid Receptor Binding

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    In synaptosomal membranes from rat and monkey brain cortex, the addition of petroselenic (18:1, cis -Δ 6 ) acid, oleic (18:1, m-Δ 9 ) acid, and vaccenic (18:1, cis -Δ 11 ) acid or their corresponding methyl esters at 0.5 Μmol/mg of membrane protein caused a similar 7–10% decrease in the microviscosity of the membrane core, whereas at the membrane surface the microviscosity was reduced 5–7% by the fatty acids but only 1% by their methyl esters. Concomi-tantly, the fatty acids, but not the methyl esters, inhibited the specific binding of the tritiated Μ-, Δ-, and K-opioids Tyr-D-Ala-Gly-(Me)Phe-Gly-ol (DAMGO), [D-Pen 2 ,D-Pen 5 ]-enkephalin (DPDPE), and U69,593, respectively. As shown with oleic acid, the sensitivity of opioid receptor binding toward inhibition by fatty acids was in the order Δ > ΜΚ k , whereby the binding of [ 3 H]DPDPE was abolished, but significant inhibition of [ 3 H]U69,593 binding, determined in membranes from monkey brain, required membrane modification with a twofold higher fatty acid concentration. Except for the unchanged K D of [ 3 H]U69,593, the inhibition by oleic acid involved both the B max and affinity of opioid binding. Cholesteryl hemisuccinate (0.5–3 Μmol/mg of protein), added to membranes previously modified by fatty acids, reversed the fluidization caused by the latter compounds and restored inhibited Μ-, Δ-, and k -opioid binding toward control values. In particular, the B max of [ 3 H]-DPDPE binding completely recovered after being undetectable. The results implicate membrane surface fluidity in the modulation of opioid receptor binding, reveal distinct sensitivity of Δ, Μ, and K receptors toward that modulation, and identify unsaturated fatty acids and cholesterol as possible endogenous regulators of opioid receptor function.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66380/1/j.1471-4159.1992.tb08432.x.pd

    Altered Transition Between Agonist-and Antagonist-Favoring States of Μ-Opioid Receptor in Brain Membranes with Modified Microviscosity

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    In unmodified synaptosomal brain membranes the presence of NaCl inhibited the binding to Μ receptors of the tritiated opioid agonists etorphine, Tyr-D-Ala-Gly-(Me)Phe-Gly-ol, and sufentanil by 53, 43, and 37%, respectively, and increased that of the antagonist [ 3 H]naltrexone by 54%. On the other hand, in membranes whose microviscosity was increased by incorporation of cholesteryl hemi-succinate (CHS) the effects of sodium on opioid agonist and antagonist binding were abolished and strongly reduced, respectively. Furthermore, in the modified membranes the ability of sodium to protect the opioid receptor from inactivation by the sulfhydryl-reactive agent N -ethyl-maleimide (NEM) was diminished. In CHS-treated membranes whose elevated microviscosity was reduced by the incorporation of oleic acid, the effectiveness of sodium in modulating opioid binding and attenuating receptor inactivation by NEM was restored. The results implicate membrane microviscosity in the mechanism by which sodium modulates the conversion between agonist-and antagonist-favoring states of Μ opioid receptor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65931/1/j.1471-4159.1993.tb03630.x.pd

    The 0nbb-decay nuclear matrix elements with self-consistent short-range correlations

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    A self-consistent calculation of nuclear matrix elements of the neutrinoless double beta decays (0nbb) of 76Ge, 82Se, 96Zr, 100Mo, 116Cd, 128Te, 130Te and 130Xe is presented in the framework of the renormalized quasiparticle random phase approximation (RQRPA) and the standard QRPA. The pairing and residual interactions as well as the two-nucleon short-range correlations are for the first time derived from the same modern realistic nucleon-nucleon potentials, namely from charge-dependent Bonn potential (CD-Bonn) and the Argonne V18 potential. In a comparison with the traditional approach of using the Miller-Spencer Jastrow correlations matrix elements for the 0nbb-decay are obtained, which are larger in magnitude. We analyze the differences among various two-nucleon correlations including those of the unitary correlation operator method (UCOM) and quantify the uncertainties in the calculated 0nbb-decay matrix elements.Comment: 11 pages, 5 figure

    Multiscale non-adiabatic dynamics with radiative decay, case study on the post-ionization fragmentation of rare-gas tetramers

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    In this supplementary material, we recollect, for reader's convenience, the general scheme of suggested multiscale model (Sec. 1), and basic informations about approaches used for pilot study: a detailed description of the interaction model (Sec. 2) and dynamical methods used for the dark dynamics step (Sec. 3) reported previously in two preceding studies [1, 2]. In addition, a detailed description of the treatment of radiative processes is also given (Sec. 4).Comment: supplementary material for parent paper; 9 pages, 1 figure; corrected formulae and misleading notation in Sec.4 (pages 7 and 8

    Transverse instabilities of multiple vortex chains in superconductor-ferromagnet bilayers

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    Using scanning tunneling microscopy and Ginzburg-Landau simulations we explore vortex configurations in magnetically coupled NbSe2_2-Permalloy superconductor-ferromagnet bilayer. The Permalloy film with stripe domain structure induces periodic local magnetic induction in the superconductor creating a series of pinning-antipinning channels for externally added magnetic flux quanta. Such laterally confined Abrikosov vortices form quasi-1D arrays (chains). The transitions between multichain states occur through propagation of kinks at the intermediate fields. At high fields we show that the system becomes non-linear due to a change in both the number of vortices and the confining potential. The longitudinal instabilities of the resulting vortex structures lead to vortices `levitating' in the anti-pinning channels.Comment: accepted in PRB-Rapid

    Searching for New Physics in Two-Neutrino Double Beta Decay

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    Motivated by non-zero neutrino masses and the possibility of New Physics discovery, a number of experiments search for neutrinoless double beta decay. While hunting for this hypothetical nuclear process, a significant amount of two-neutrino double beta decay data has become available. Although these events are regarded and studied mostly as the background of neutrinoless double beta decay, they can be also used to probe physics beyond the Standard Model. In this paper we show how the presence of right-handed leptonic currents would affect the energy distribution and angular correlation of the outgoing electrons in two-neutrino double beta decay. Consequently, we estimate constraints imposed by currently available data on the existence of right-handed neutrino interactions without having to assume their nature. In this way our results complement the bounds coming from the non-observation of neutrinoless double beta decay as they limit also the exotic interactions of Dirac neutrinos. We perform a detailed calculation of two-neutrino double beta decay under the presence of exotic (axial-)vector currents and we demonstrate that current experimental searches can be competitive to existing limits.Comment: 28 pages, 6 figures, including appendi

    Time-inconsistent Planning: Simple Motivation Is Hard to Find

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    With the introduction of the graph-theoretic time-inconsistent planning model due to Kleinberg and Oren, it has been possible to investigate the computational complexity of how a task designer best can support a present-biased agent in completing the task. In this paper, we study the complexity of finding a choice reduction for the agent; that is, how to remove edges and vertices from the task graph such that a present-biased agent will remain motivated to reach his target even for a limited reward. While this problem is NP-complete in general, this is not necessarily true for instances which occur in practice, or for solutions which are of interest to task designers. For instance, a task designer may desire to find the best task graph which is not too complicated. We therefore investigate the problem of finding simple motivating subgraphs. These are structures where the agent will modify his plan at most kk times along the way. We quantify this simplicity in the time-inconsistency model as a structural parameter: The number of branching vertices (vertices with out-degree at least 22) in a minimal motivating subgraph. Our results are as follows: We give a linear algorithm for finding an optimal motivating path, i.e. when k=0k=0. On the negative side, we show that finding a simple motivating subgraph is NP-complete even if we allow only a single branching vertex --- revealing that simple motivating subgraphs are indeed hard to find. However, we give a pseudo-polynomial algorithm for the case when kk is fixed and edge weights are rationals, which might be a reasonable assumption in practice.Comment: An extended abstract of this paper is accepted at AAAI 202
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