Synchronisation of linear continuous multi-agent systems with switching topology and communication delay

A distributed dynamic output feedback control is designed by Scardovi and Sepulchre for the synchronization of a network of identical linear systems, known as agents in literature. The design is based on some mild conditions allowing switching topology. But it assumes that there is no time delay in signal transfer between the neighbouring agents. In this paper we extend their work to include known time delay in communications. Furthermore, our design has some special features: (a) the delay can be arbitrary and only need to be uniformly bounded by a constant, (b) the conditions that time delay should be the same and sufficiently small in some literature are not required here, and (c) no local buffer is required to store past data due to time-delay effect

A Liquid Metal Flume for Free Surface Magnetohydrodynamic Experiments

We present an experiment designed to study magnetohydrodynamic effects in free-surface channel flow. The wide aspect ratio channel (the width to height ratio is about 15) is completely enclosed in an inert atmosphere to prevent oxidization of the liquid metal. A custom-designed pump reduces entrainment of oxygen, which was found to be a problem with standard centrifugal and gear pumps. Laser Doppler Velocimetry experiments characterize velocity profiles of the flow. Various flow constraints mitigate secondary circulation and end effects on the flow. Measurements of the wave propagation characteristics in the liquid metal demonstrate the surfactant effect of surface oxides and the damping of fluctuations by a cross-channel magnetic field

A Systematic Analysis of the Lepton Polarization Asymmetries in the Rare B Decay, B -> X_s\tau^+\tau^-

The most general model-independent analysis of the lepton polarization asymmetries in the rare B decay, \Bstt, is presented. We present the longitudinal, normal and transverse polarization asymmetries for the $\tau^+$ and $\tau^-$, and combinations of them, as functions of the Wilson coefficients of twelve independent four-Fermi interactions, ten of them local and two nonlocal. These procedures will tell us which type of operators contributes to the process. And it will be very useful to pin down new physics systematically, once we have the experimental data with high statistics and a deviation from the Standard Model is found.Comment: 24 pages, 8 figures, LaTe

Quark initiated coherent diffractive production of muon pair and W boson at hadron colliders

The large transverse momentum muon pair and W boson productions in the quark initiated coherent diffractive processes at hadron colliders are discussed under the framework of the two-gluon exchange parametrization of the Pomeron model. In this approach, the production cross sections are related to the small-x off-diagonal gluon distribution and the large-x quark distribution in the proton (antiproton). By approximating the off-diagonal gluon distribution by the usual gluon distribution function, we estimate the production rates of these processes at the Fermilab Tevatron.Comment: 11pages, 6 PS figures, to appear in PR

Accessing Transversity in Double-Spin Asymmetries at the BNL-RHIC

We give upper bounds for transverse double-spin asymmetries in polarized proton-proton collisions by saturating the positivity constraint for the transversity densities at a low hadronic resolution scale. We consider prompt photon, jet, pion, and heavy flavor production at the BNL Relativistic Heavy Ion Collider (RHIC). Estimates of the expected statistical accuracy for such measurements are presented, taking into account the acceptance of the RHIC detectors.Comment: 15 pages, LaTeX, 2 figures as eps file

Diffractive light quark jet production at hadron colliders in the two-gluon exchange model

Massless quark and antiquark jet production at large transverse momentum in the coherent diffractive processes at hadron colliders is calculated in the two-gluon exchange parametrization of the Pomeron model. We use the helicity amplitude method to calculate the cross section formula. We find that for the light quark jet production the diffractive process is related to the differential off-diagonal gluon distribution function in the proton. We estimate the production rate for this process at the Fermilab Tevatron by approximating the off-diagonal gluon distribution function by the usual diagonal gluon distribution in the proton. And we find that the cross sections for the diffractive light quark jet production and the charm quark jet production are in the same order of magnitude. We also use the helicity amplitude method to calculate the diffractive charm jet production at hadron colliders, by which we reproduce the leading logarithmic approximation result of this process we previously calculated.Comment: 15 pages, 4 PS figures, Revte

Variation in assignment of the COPD patients into a GOLD group according to symptoms severity

Introduction: The Global Organization of Lung Disease (GOLD) classifies patients with chronic obstructive pulmonary disease (COPD) taking into account the symptoms. The modified Medical Research Council’s dyspnea scale (mMRC) and the COPD assessment test (CAT) are used to assess these symptoms. In this study, we analyze the concordance of GOLD classification using mMRC and CAT. Patients and Methods: This is an observational study of a cohort of 169 patients with COPD, who were classified following the GOLD 2017 recommendations, using both mMRC and CAT. A concordance analysis was applied, and a ROC curve was generated to identify the CAT score that best concorded with the mMRC scale. Results: The concordance for the GOLD groups classified by CAT and mMRC was moderate (kappa 0.492). For mMRC score of 1 and 2, a CAT score of =9 and =16 showed the maximum value of the Youden index, respectively. By reclassifying the patients with the new cut-off points obtained, the best concordance was obtained between the cut-off point for CAT of 16 and for mMRC of 2, followed by CAT of 9 and mMRC of 1. Conclusion: Because of the deficient concordance between CAT and mMRC, we propose the use of new cut-off points in future updates of the GOLD strategy

Unitary relation between a harmonic oscillator of time-dependent frequency and a simple harmonic oscillator with and without an inverse-square potential

The unitary operator which transforms a harmonic oscillator system of time-dependent frequency into that of a simple harmonic oscillator of different time-scale is found, with and without an inverse-square potential. It is shown that for both cases, this operator can be used in finding complete sets of wave functions of a generalized harmonic oscillator system from the well-known sets of the simple harmonic oscillator. Exact invariants of the time-dependent systems can also be obtained from the constant Hamiltonians of unit mass and frequency by making use of this unitary transformation. The geometric phases for the wave functions of a generalized harmonic oscillator with an inverse-square potential are given.Comment: Phys. Rev. A (Brief Report), in pres

Which phase is measured in the mesoscopic Aharonov-Bohm interferometer?

Mesoscopic solid state Aharonov-Bohm interferometers have been used to measure the "intrinsic" phase, $\alpha_{QD}$, of the resonant quantum transmission amplitude through a quantum dot (QD). For a two-terminal "closed" interferometer, which conserves the electron current, Onsager's relations require that the measured phase shift $\beta$ only "jumps" between 0 and $\pi$. Additional terminals open the interferometer but then $\beta$ depends on the details of the opening. Using a theoretical model, we present quantitative criteria (which can be tested experimentally) for $\beta$ to be equal to the desired $\alpha_{QD}$: the "lossy" channels near the QD should have both a small transmission and a small reflection