Modeling magnetospheric fields in the Jupiter system

The various processes which generate magnetic fields within the Jupiter system are exemplary for a large class of similar processes occurring at other planets in the solar system, but also around extrasolar planets. Jupiter's large internal dynamo magnetic field generates a gigantic magnetosphere, which is strongly rotational driven and possesses large plasma sources located deeply within the magnetosphere. The combination of the latter two effects is the primary reason for Jupiter's main auroral ovals. Jupiter's moon Ganymede is the only known moon with an intrinsic dynamo magnetic field, which generates a mini-magnetosphere located within Jupiter's larger magnetosphere including two auroral ovals. Ganymede's magnetosphere is qualitatively different compared to the one from Jupiter. It possesses no bow shock but develops Alfv\'en wings similar to most of the extrasolar planets which orbit their host stars within 0.1 AU. New numerical models of Jupiter's and Ganymede's magnetospheres presented here provide quantitative insight into the processes that maintain these magnetospheres. Jupiter's magnetospheric field is approximately time-periodic at the locations of Jupiter's moons and induces secondary magnetic fields in electrically conductive layers such as subsurface oceans. In the case of Ganymede, these secondary magnetic fields influence the oscillation of the location of its auroral ovals. Based on dedicated Hubble Space Telescope observations, an analysis of the amplitudes of the auroral oscillations provides evidence that Ganymede harbors a subsurface ocean. Callisto in contrast does not possess a mini-magnetosphere, but still shows a perturbed magnetic field environment. Callisto's ionosphere and atmospheric UV emission is different compared to the other Galilean satellites as it is primarily been generated by solar photons compared to magnetospheric electrons.Comment: Chapter for Book: Planetary Magnetis

Numerical convergence of the block-maxima approach to the Generalized Extreme Value distribution

In this paper we perform an analytical and numerical study of Extreme Value distributions in discrete dynamical systems. In this setting, recent works have shown how to get a statistics of extremes in agreement with the classical Extreme Value Theory. We pursue these investigations by giving analytical expressions of Extreme Value distribution parameters for maps that have an absolutely continuous invariant measure. We compare these analytical results with numerical experiments in which we study the convergence to limiting distributions using the so called block-maxima approach, pointing out in which cases we obtain robust estimation of parameters. In regular maps for which mixing properties do not hold, we show that the fitting procedure to the classical Extreme Value Distribution fails, as expected. However, we obtain an empirical distribution that can be explained starting from a different observable function for which Nicolis et al. [2006] have found analytical results.Comment: 34 pages, 7 figures; Journal of Statistical Physics 201

Effective lagrangian description of top production and decay

We propose a rather general description of residual New Physics (NP) effects on the top quark couplings. These effects are described in terms of 20 gauge invariant $dim=6$ operators involving gauge and Higgs bosons as well as quarks of the third family. We compute their implications for the $\gamma t\bar t$, $Z t \bar t$ and $tbW$ vertices and study their observability in the process $e^-e^+ \to t\bar t$ with $t\to bW \to b\ell^+\nu_\ell$. We present results for the integrated cross section, the angular distribution and various decay distribution and polarization asymmetries for NLC energies of $0.5-2~TeV$. Observability limits are discussed and interpreted in terms of the NP scales associated to each operator through the unitarity constraints. The general landscape of the residual NP effects in the heavy quark and bosonic sectors is also presented.Comment: 36 pages (9 figures available through email in .uu form, e-mail: [email protected]

Low- and high-mass components of the photon distribution functions

The structure of the general solution of the inhomogeneous evolution equations allows the separation of a photon structure function into perturbative (``anomalous") and non-perturbative contributions. The former part is fully calculable, and can be identified with the high-mass contributions to the dispersion integral in the photon mass. Properly normalized ``state" distributions can be defined, where the \gamma\to\qqbar splitting probability is factored out. These state distributions are shown to be useful in the description of the hadronic event properties, and necessary for a proper eikonalization of jet cross sections. Convenient parametrizations are provided both for the state and for the full anomalous parton distributions. The non-perturbative parts of the parton distribution functions of the photon are identified with the low-mass contributions to the dispersion integral. Their normalizations, as well as the value of the scale $Q_0$ at which the perturbative parts vanish, are fixed by approximating the low-mass contributions by a discrete, finite sum of vector mesons. The shapes of these hadronic distributions are fitted to the available data on $F_2^\gamma(x,Q^2)$. Parametrizations are provided for $Q_0=0.6\,$GeV and $Q_0=2\,$GeV, both in the DIS and the $\overline{\mathrm{MS}}$ factorization schemes. The full parametrizations are extended towards virtual photons. Finally, the often-used ``FKP-plus-TPC/$2\gamma$" solution for $F_2^\gamma(x,Q^2)$ is commented upon.Comment: 33 pages, Latex, 6 Z-compressed and uuencoded figure

The non-random walk of stock prices: The long-term correlation between signs and sizes

We investigate the random walk of prices by developing a simple model relating the properties of the signs and absolute values of individual price changes to the diffusion rate (volatility) of prices at longer time scales. We show that this benchmark model is unable to reproduce the diffusion properties of real prices. Specifically, we find that for one hour intervals this model consistently over-predicts the volatility of real price series by about 70%, and that this effect becomes stronger as the length of the intervals increases. By selectively shuffling some components of the data while preserving others we are able to show that this discrepancy is caused by a subtle but long-range non-contemporaneous correlation between the signs and sizes of individual returns. We conjecture that this is related to the long-memory of transaction signs and the need to enforce market efficiency.Comment: 9 pages, 5 figures, StatPhys2

Study protocol for a randomised controlled trial of diacerein versus placebo to treat knee osteoarthritis with effusion-synovitis (DICKENS)

Published online: 11 September 2022Background: There is an unmet need for treatments for knee osteoarthritis (OA). Effusion-synovitis is a common inflammatory phenotype of knee OA and predicts knee pain and structural degradation. Anti-inflammatory therapies, such as diacerein, may be effective for this phenotype. While diacerein is recommended for alleviating pain in OA patients, evidence for its effectiveness is inconsistent, possibly because studies have not targeted patients with an inflammatory phenotype. Therefore, we will conduct a multi-centre, randomised, placebo-controlled double-blind trial to determine the effect of diacerein on changes in knee pain and effusion-synovitis over 24 weeks in patients with knee OA and magnetic resonance imaging (MRI)-defined effusion-synovitis. Methods: We will recruit 260 patients with clinical knee OA, significant knee pain, and MRI-detected effusion-synovitis in Hobart, Melbourne, Adelaide, and Perth, Australia. They will be randomly allocated to receive either diacerein (50mg twice daily) or identical placebo for 24 weeks. MRI of the study knee will be performed at screening and after 24 weeks of intervention. The primary outcome is improvement in knee pain at 24 weeks as assessed by a 100-mm visual analogue scale (VAS). Secondary outcomes include improvement in volumetric (ml) and semi-quantitative (Whole-Organ Magnetic Resonance Imaging Score, 0–3) measurements of effusion-synovitis using MRI over 24 weeks, and improvement in knee pain (VAS) at 4, 8, 12, 16, and 20 weeks. Intention-to-treat analyses of primary and secondary outcomes will be performed as the primary analyses. Per protocol analyses will be performed as the secondary analyses. Discussion: This study will provide high-quality evidence to determine whether diacerein improves pain, changes disease trajectory, and slows disease progression in OA patients with effusion-synovitis. If diacerein proves effective, this has the potential to significantly benefit the substantial proportion (up to 60%) of knee OA patients with an inflammatory phenotype. Trial registration: Australian and New Zealand Clinical Trial Registry ACTRN 12618 00165 6224. Registered on 08 October 2018.Guoqi Cai, Graeme Jones, Flavia M. Cicuttini, Anita E. Wluka, Yuanyuan Wang, Catherine Hill, Helen Keen, Benny Antony, Xia Wang, Barbara de Graaff, Michael Thompson, Tania Winzenberg, Kathy Buttigieg and Dawn Aitke

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio