69,002 research outputs found

    Boundedness of Pseudodifferential Operators on Banach Function Spaces

    Full text link
    We show that if the Hardy-Littlewood maximal operator is bounded on a separable Banach function space X(Rn)X(\mathbb{R}^n) and on its associate space X(Rn)X'(\mathbb{R}^n), then a pseudodifferential operator Op(a)\operatorname{Op}(a) is bounded on X(Rn)X(\mathbb{R}^n) whenever the symbol aa belongs to the H\"ormander class Sρ,δn(ρ1)S_{\rho,\delta}^{n(\rho-1)} with 0<ρ10<\rho\le 1, 0δ<10\le\delta<1 or to the the Miyachi class Sρ,δn(ρ1)(ϰ,n)S_{\rho,\delta}^{n(\rho-1)}(\varkappa,n) with 0δρ10\le\delta\le\rho\le 1, 0δ00\le\delta0. This result is applied to the case of variable Lebesgue spaces Lp()(Rn)L^{p(\cdot)}(\mathbb{R}^n).Comment: To appear in a special volume of Operator Theory: Advances and Applications dedicated to Ant\'onio Ferreira dos Santo

    Relationship between membrane phosphatidylinositol-4,5-bisphosphate and receptor-mediated inhibition of native neuronal M channels

    Get PDF
    The relationship between receptor-induced membrane phosphatidylinositol-4'5'-bisphosphate (PIP2) hydrolysis and M-current inhibition was assessed in single-dissociated rat sympathetic neurons by simultaneous or parallel recording of membrane current and membrane-to-cytosol translocation of the fluorescent PIP2/inositol 1,4,5-trisphosphate (IP3)-binding peptide green fluorescent protein-tagged pleckstrin homology domain of phospholipase C (GFP-PLC delta-PH). The muscarinic receptor agonist oxotremorine-M produced parallel time- and concentration-dependent M-current inhibition and GFP-PLC delta-PH translocation; bradykinin also produced parallel time- dependent inhibition and translocation. Phosphatidylinositol-4-phosphate-5-kinase (PI5-K) overexpression reduced both M-current inhibition and GFP-PLC delta-PH translocation by both oxotremorine-M and bradykinin. These effects were partly reversed by wortmannin, which inhibits phosphatidylinositol-4-kinase (PI4-K). PI5-K overexpression also reduced the inhibitory action of oxotremorine-M on PIP2-gated G-protein-gated inward rectifier (Kir3.1/3.2) channels; bradykinin did not inhibit these channels. Overexpression of neuronal calcium sensor-1 protein (NCS-1), which increases PI4-K activity, did not affect responses to oxotremorine-M but reduced both fluorescence translocation and M-current inhibition by bradykinin. Using an intracellular IP3 membrane fluorescence-displacement assay, initial mean concentrations of membrane [PIP2] were estimated at 261 mu M (95% confidence limit; 192-381 mu M), rising to 693 mu M (417-1153 mu M) in neurons overexpressing PI5-K. Changes in membrane [PIP2] during application of oxotremorine-M were calculated from fluorescence data. The results, taken in conjunction with previous data for KCNQ2/3 (Kv7.2/Kv7.3) channel gating by PIP2 (Zhang et al., 2003), accorded with the hypothesis that the inhibitory action of oxotremorine-M on M current resulted from depletion of PIP2. The effects of bradykinin require additional components of action, which might involve IP3-induced Ca2+ release and consequent M-channel inhibition (as proposed previously) and stimulation of PIP2 synthesis by Ca2+-dependent activation of NCS-1

    Unique vortex and stripe domain structures in PbTiO 3 epitaxial nanodots

    Get PDF
    The domain structures of PbTiO 3 epitaxial nanodots under the influences of depolarization fields and mismatch strains have been studied using three dimensional phase field simulations. The single-vortex structure and mixed domain configuration, which consisted of zigzag stripe domain and closure dipole flux near the interfaces, were found to be effective in annihilating the depolarization fields in the isotropically tensile and compressive ferroelectric nanodots, respectively. These domain structures were produced by the combined effect of electrostatic and mismatch elastic energies. The width of stripe domain was found to be related to the volume percentage of polarization dipoles along the z-axis, which varied remarkably with the change of compressive mismatch strain. In the case of nanodots under anisotropic mismatch strains, double-vortex domain patterns and stripe domains with nearly straight domain walls were formed. Moreover, the domain structures with electrostatic energy neglected were also studied. © 2011 Elsevier Ltd. All rights reserved.postprin

    Early Literacy in Informal Settings: Supporting Home Literacy Practices

    Full text link
    Early literacy is a key factor in a childâs development in the years before they start school. It often is used as one of the key indicators of a childâs early development, and as shown in various longitudinal studies, it affects the way children progress through school and their later life. As the evidence of the benefits of early intervention accumulates, there needs to be more recognition of the place of early literacy within early intervention strategies in disadvantaged communities. A significant proportion of children, living in disadvantaged communities, and outside the formal early childhood system (pre-school, long day care or occasional care), start school with little exposure to any significant level or range of early literacy practices. This paper reports on a qualitative study with Aboriginal and CALD mothers and carers in an inner city part of Sydney, who attended mothers groups or supported playgroups. Taking a socio-cultural approach the study explores the views of front-line community workers and the experiences of mothers and carers with early literacy in a range of informal community based settings and programs. The research has implications for the development of strategies to support the development of programs in informal settings and the development of strategies to engage and support parents and carers

    Silent MST approximation for tiny memory

    Get PDF
    In network distributed computing, minimum spanning tree (MST) is one of the key problems, and silent self-stabilization one of the most demanding fault-tolerance properties. For this problem and this model, a polynomial-time algorithm with O(log2 ⁣n)O(\log^2\!n) memory is known for the state model. This is memory optimal for weights in the classic [1,poly(n)][1,\text{poly}(n)] range (where nn is the size of the network). In this paper, we go below this O(log2 ⁣n)O(\log^2\!n) memory, using approximation and parametrized complexity. More specifically, our contributions are two-fold. We introduce a second parameter~ss, which is the space needed to encode a weight, and we design a silent polynomial-time self-stabilizing algorithm, with space O(logns)O(\log n \cdot s). In turn, this allows us to get an approximation algorithm for the problem, with a trade-off between the approximation ratio of the solution and the space used. For polynomial weights, this trade-off goes smoothly from memory O(logn)O(\log n) for an nn-approximation, to memory O(log2 ⁣n)O(\log^2\!n) for exact solutions, with for example memory O(lognloglogn)O(\log n\log\log n) for a 2-approximation

    A vine copula mixed effect model for trivariate meta-analysis of diagnostic test accuracy studies accounting for disease prevalence

    Get PDF
    A bivariate copula mixed model has been recently proposed to synthesize diagnostic test accuracy studies and it has been shown that it is superior to the standard generalized linear mixed model in this context. Here, we call trivariate vine copulas to extend the bivariate meta-analysis of diagnostic test accuracy studies by accounting for disease prevalence. Our vine copula mixed model includes the trivariate generalized linear mixed model as a special case and can also operate on the original scale of sensitivity, specificity, and disease prevalence. Our general methodology is illustrated by re-analyzing the data of two published meta-analyses. Our study suggests that there can be an improvement on trivariate generalized linear mixed model in fit to data and makes the argument for moving to vine copula random effects models especially because of their richness, including reflection asymmetric tail dependence, and computational feasibility despite their three dimensionality

    Proprioceptive changes impair balance control in individuals with chronic obstructive pulmonary disease

    Get PDF
    Copyright @ 2013 Janssens et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Introduction: Balance deficits are identified as important risk factors for falling in individuals with chronic obstructive pulmonary disease (COPD). However, the specific use of proprioception, which is of primary importance during balance control, has not been studied in individuals with COPD. The objective was to determine the specific proprioceptive control strategy during postural balance in individuals with COPD and healthy controls, and to assess whether this was related to inspiratory muscle weakness. Methods: Center of pressure displacement was determined in 20 individuals with COPD and 20 age/gender-matched controls during upright stance on an unstable support surface without vision. Ankle and back muscle vibration were applied to evaluate the relative contribution of different proprioceptive signals used in postural control. Results: Individuals with COPD showed an increased anterior-posterior body sway during upright stance (p=0.037). Compared to controls, individuals with COPD showed an increased posterior body sway during ankle muscle vibration (p=0.047), decreased anterior body sway during back muscle vibration (p=0.025), and increased posterior body sway during simultaneous ankle-muscle vibration (p=0.002). Individuals with COPD with the weakest inspiratory muscles showed the greatest reliance on ankle muscle input when compared to the stronger individuals with COPD (p=0.037). Conclusions: Individuals with COPD, especially those with inspiratory muscle weakness, increased their reliance on ankle muscle proprioceptive signals and decreased their reliance on back muscle proprioceptive signals during balance control, resulting in a decreased postural stability compared to healthy controls. These proprioceptive changes may be due to an impaired postural contribution of the inspiratory muscles to trunk stability. Further research is required to determine whether interventions such as proprioceptive training and inspiratory muscle training improve postural balance and reduce the fall risk in individuals with COPD.This work was supported by the Research Foundation – Flanders (FWO) grants 1.5.104.03, G.0674.09, G.0598.09N and G.0871.13N

    Effects of film thickness and mismatch strains on magnetoelectric coupling in vertical heteroepitaxial nanocomposite thin films

    Get PDF
    The phase field model is adopted to study the magnetoelectric coupling effects in vertical heteroepitaxial nanocomposite thin films. Both the lateral epitaxial strains between the film and the substrate and the vertical epitaxial strains between the ferroelectric and ferromagnetic phases are accounted for in the model devised. The effects of the film thickness on the magnetic-field- induced electric polarization (MIEP) are investigated. The results obtained show that the MIEP is strongly dependent on the film thickness, as well as on the vertical and lateral epitaxial strains. © 2011 American Institute of Physics.published_or_final_versio

    The Cost of Monitoring Alone

    Full text link
    We compare the succinctness of two monitoring systems for properties of infinite traces, namely parallel and regular monitors. Although a parallel monitor can be turned into an equivalent regular monitor, the cost of this transformation is a double-exponential blowup in the syntactic size of the monitors, and a triple-exponential blowup when the goal is a deterministic monitor. We show that these bounds are tight and that they also hold for translations between corresponding fragments of Hennessy-Milner logic with recursion over infinite traces.Comment: 22 page
    corecore