858 research outputs found

    Statistical Inspired Parton Distributions and the Violation of QPM Sum Rules

    Get PDF
    A quantum statistical parametrization of parton distributions has been considered. In this framework, the exclusion Pauli principle connects the violation of the Gottfried sum rule with the Ellis and Jaffe one, and implies a defect in the Bjorken sum rule. However, in terms of standard parametrizations of the polarized distributions a good description of the data is obtained once a large gluon polarization is provided. Interestingly, in this description there is no violation of the Bjorken sum rule.Comment: 10 pages, LateX + 15 figures, Talk given at ``Hadrons 96'' Workshop, Novy Svet (CRIMEA), June 9-1

    Circuit quantum acoustodynamics with surface acoustic waves

    Full text link
    The experimental investigation of quantum devices incorporating mechanical resonators has opened up new frontiers in the study of quantum mechanics at a macroscopic level1,2^{1,2}. Superconducting microwave circuits have proven to be a powerful platform for the realisation of such quantum devices, both in cavity optomechanics3,4^{3,4}, and circuit quantum electro-dynamics (QED)5,6^{5,6}. While most experiments to date have involved localised nanomechanical resonators, it has recently been shown that propagating surface acoustic waves (SAWs) can be piezoelectrically coupled to superconducting qubits7,8^{7,8}, and confined in high-quality Fabry-Perot cavities up to microwave frequencies in the quantum regime9^{9}, indicating the possibility of realising coherent exchange of quantum information between the two systems. Here we present measurements of a device in which a superconducting qubit is embedded in, and interacts with, the acoustic field of a Fabry-Perot SAW cavity on quartz, realising a surface acoustic version of cavity quantum electrodynamics. This quantum acoustodynamics (QAD) architecture may be used to develop new quantum acoustic devices in which quantum information is stored in trapped on-chip surface acoustic wavepackets, and manipulated in ways that are impossible with purely electromagnetic signals, due to the 10510^{5} times slower speed of travel of the mechanical waves.Comment: 12 pages, 9 figures, 1 tabl

    Quantum Statistical Parton Distributions and the Spin Crisis

    Get PDF
    Quantum statistical distributions for the partons provide a fair description of deep inelastic scattering data at Q2=3Q^2 = 3 and 10(GeV/c)210 (GeV/c)^2. The study of the polarized structure functions seems to suggest an alternative possible solution of the {\it spin crisis} based on the Pauli principle. In this scheme, in fact, the defects of the Gottfried sum rule and Ellis--Jaffe sum rule for proton, result strongly connected. This possibility finds particular evidence from the phenomenological observation that the relation Δu=2F~+ud1\Delta u = 2 \tilde{F} + u - d -1 seems well satisfied by parton distributions.Comment: plain LaTeX, 18 pages + 14 figures, revised version with changes in the text and in some figures, to appear in Progress of Theor. Phys. Vol. 96 (October 1996) No.

    Anti-aggressive effects of the selective high-efficacy 'biased' 5-HT1A receptor agonists F15599 and F13714 in male WTG rats

    Get PDF
    BACKGROUND: The serotonin (5-HT) deficiency hypothesis of aggression is being seriously challenged by pharmacological data showing robust anti-aggressive effects of 5-HT1A receptor agonists in dose ranges that concomitantly inhibit 5-HT neurotransmission. Hence, an adequate interpretation of the role of 5-HT activity in regulating aggression depends on elucidating the predominant site of action, i.e., raphe presynaptic autoreceptors versus forebrain postsynaptic heteroreceptors, of these 5-HT1A receptor agonists. OBJECTIVES: The present experiments investigated the anti-aggressive properties of the selective 5-HT1A receptor agonists F15599 that preferentially target postsynaptic 5-HT1A heteroreceptors in the frontal cortex and F13714 that more preferentially activates raphe somatodendritic 5-HT1A autoreceptors. METHODS: Both 'biased' agonists were acutely administered intraperitoneally in aggressive resident male WTG rats confronting an intruder. RESULTS: Systemic administration of F15599 and F13714 exerted very potent (ID50 = 0.095 and 0.0059 mg/kg, respectively) anti-aggressive effects. At 4.5-fold higher dose ranges, the anti-aggressive effects were accompanied by concomitant motor inactivity and/or reduction of social engagement. Pretreatment with WAY-100635 counteracted the behavioural effects of both agonists. CONCLUSIONS: Overall, the qualitatively similar but quantitatively different anti-aggressive profiles of F15599 and F13714 largely correspond to their distinct 5-HT1A receptor binding/activation potencies. Moreover, the marked anti-aggressive potency of F13714 adds additional support for a critical role of raphe somatodendritic 5-HT1A autoreceptors, and hence phasic 5-HT neuron activity, in the initiation/execution of aggressive actions

    Robustness Analysis for Terminal Phases of Re-entry Flight

    Get PDF
    Advancements in the current practices used in robustness analysis for FCS design refinement by introducing a method that takes into account nonlinear effects of multiple uncertainties over the whole trajectory, to be used before robustness is finally assessed with MC analysis has been reported. Current practice in FCS robustness analysis for this kind of application mainly relies on the theory of linear time-invariant (LTI) systems. The method delivers feedback on the causes of requirement violation and adopts robustness criteria directly linked to the original mission or system requirements, such as those employed in MC analyses. The nonlinear robustness criterion proposed in the present work is based on the practical stability and/or finite time stability concepts. The practical stability property improves the accuracy in robustness evaluation with respect to frozen-time approaches, thus reducing the risk of discovering additional effects during robustness verification with Monte Carlo techniques

    A hybrid approach to robustness analyses of flight control laws in re-entry applications

    Get PDF
    The present paper aims at improving the efficiency of the robustness analyses of flight control laws with respect to conventional techniques, especially when applied to vehicles following time-varying reference trajectories, such as in an atmospheric re-entry. A nonlinear robustness criterion is proposed, stemming from the practical stability framework, which allows dealing effectively with such cases. A novel approach is presented, which exploits the convexity of linear time varying systems, coupled to an approximate description of the original nonlinear system by a certain number of its time-varying linearizations. The suitability of the approximating systems is evaluated in a probabilistic fashion making use of the unscented transformation technique. The effectiveness and potentials of the method are ascertained by application to the robustness analysis of the longitudinal flight control laws of the Italian Aerospace Research Center (CIRA) experimental vehicle USV

    W+WW^+W^- production at hadron colliders in NNLO QCD

    Get PDF
    Charged gauge boson pair production at the Large Hadron Collider allows detailed probes of the fundamental structure of electroweak interactions. We present precise theoretical predictions for on-shell W+WW^+W^- production that include, for the first time, QCD effects up to next-to-next-to-leading order in perturbation theory. As compared to next-to-leading order, the inclusive W+WW^+W^- cross section is enhanced by 9% at 7 TeV and 12% at 14 TeV. The residual perturbative uncertainty is at the 3% level. The severe contamination of the W+WW^+W^- cross section due to top-quark resonances is discussed in detail. Comparing different definitions of top-free W+WW^+W^- production in the four and five flavour number schemes, we demonstrate that top-quark resonances can be separated from the inclusive W+WW^+W^- cross section without significant loss of theoretical precision.Comment: 7 pages, 3 figure

    A linear time-varying approach for robustness analyses of a re-entry flight technology demonstrator

    Get PDF
    A novel robustness analysis technique is proposed for atmospheric re-entry applications. The problem is stated as a finite time stability (FTS) analysis of linear time-varying (LTV) systems on a compact time domain, subject to bounded variations in initial state and unknown parameters. The FTS property is formulated as the inclusion of all the possible system trajectories into a pre-specified time-varying subset of the state space. Based on assuming the involved sets are polytopes, the proposed approach allows deducing the system FTS from the property verification on a limited number of numerically computed system trajectories. An additional result is presented which allows determination of a conservative estimate of the maximum norm-bound of time-varying perturbations under which the LTV system remains finite time stable. Results of the application of the proposed technique to a re-entry technology demonstrator are presented which demonstrate its effectiveness in complementing conventional linear time invariant-based analyses. Results also show that it is computationally viable and allows linking the system robustness to a quantitative analysis of the system trajectory dispersion around the nominal one due to concurrent initial state dispersion and uncertain parameters effects, which aids in evaluating mission objectives fulfillment

    Evaluation of immunization practices in Naples, Italy.

    Get PDF
    This paper reports the results of a survey on vaccination coverage among children born in January 1995 and residing at the beginning of the study (March 1998) in the city of Naples, Italy. The percentages vaccinated, at various times from birth, with oral polio vaccine (OPV), have been compared with those found in a similar survey conducted at the end of 1985 regarding the cohort of children born in June 1983. By the fourth month of life 67% of the 1995 cohort were vaccinated with the first doses of OPV, an increase of about 26% on that found in the 1983 cohort. Similar results were found with the second doses. Among the 1995 cohort 49% were vaccinated with the third dose of OPV within the thirteenth month of life; the corresponding value for the 1983 cohort was 33%. Within the twenty-fourth month of life, in the 1995 cohort, 86% completed the primary cycle of vaccination with OPV; the corresponding figure for the 1983 cohort was 65%. At the end of the third year of life 80% of the 1995 cohort received the fourth dose of OPV. A significant association has been found between socioeconomic status and coverage level
    corecore