30,862 research outputs found

    Absence of Significant Light-Induced Changes in cAMP Levels in Sporangiophores of Phycomyces blakesleeanus

    Get PDF
    We were unable to find transient changes in the amount of cAMP or cGMP that had been proposed to mediate the light-growth response in sporangiophores of Phycomyces blakesleeanus

    Multigrid method for nearly singular and slightly indefinite problems

    Get PDF
    This paper deals with nearly singular, possibly indefinite problems for which the usual multigrid solvers converge very slowly or even diverge. The main difficulty is related to some badly approximated smooth functions which correspond to eigenfunctions with nearly zero eigenvalues. A correction to the usual coarse-grid equations is derived, both in the correction scheme and in the full approximation scheme. The performance of the new algorithm using this correction is essentially as that of usual multigrid for definite problems

    Multigrid solutions to quasi-elliptic schemes

    Get PDF
    Quasi-elliptic schemes arise from central differencing or finite element discretization of elliptic systems with odd order derivatives on non-staggered grids. They are somewhat unstable and less accurate then corresponding staggered-grid schemes. When usual multigrid solvers are applied to them, the asymptotic algebraic convergence is necessarily slow. Nevertheless, it is shown by mode analyses and numerical experiments that the usual FMG algorithm is very efficient in solving quasi-elliptic equations to the level of truncation errors. Also, a new type of multigrid algorithm is presented, mode analyzed and tested, for which even the asymptotic algebraic convergence is fast. The essence of that algorithm is applicable to other kinds of problems, including highly indefinite ones

    Auditor independence and audit risk: a reconceptualisation

    Get PDF
    The principles-based U.K. regulatory framework for auditor independence (Chartered Accountants Joint Ethics Committee 1996), which was adopted in 1997, identifies threats to independence in fact, independence in appearance, and the safeguards that control these threats. These principles are incorporated in the International Federation of Accountants (IFAC 2001) ethics framework. Drawing on six case studies of interactions involving significant accounting issues between audit engagement partners and finance directors in U.K.-listed companies, we analyze the threats and safeguards to auditor independence in fact that are relevant to the outcome of each interaction. Despite the U.K.'s comprehensive regulatory framework for independence, audit quality control, and independent inspection of firms, not all the interactions have a fully compliant outcome. Independence in fact is compromised where the safeguards in the framework are insufficient defense against the threats, particularly regarding intimidation and bullying during the audit process. Further examples of existing threats are identified and additional threats emerge, in particular an urgency threat, and a loss of face threat. Management motivation is found to be a key driver of pressure. Threats to independence arising within audit firms are not recognized in the current U.K. audit risk model. An extended risk model incorporating within-firm risk is suggested. This study demonstrates the need for continual improvement to regulatory frameworks; in particular it supports the recent U.S. Securities and Exchange Commission (SEC) rule on improper influence on the conduct of audits (Securities and Exchange Commission 2003a)

    A grounded theory model of auditor-client negotiations

    Get PDF
    The central research question addressed in this paper is 'How do companies and their auditors resolve important audit issues?' In-depth interviews are conducted with the audit partners and finance directors of a varied group of six major UK listed companies who had recently experienced audit interactions involving 22 significant accounting issues. A grounded theory model is developed of the negotiation process and the factors that influence the nature of the outcome of interactions. This model identifies, as principal analytical categories, a range of general relationship factors and specific accounting issue factors that influence aspects of the negotiation process. These aspects include the parties involved, the strategies adopted, the quality of the financial reporting outcome and the ease with which it is achieved. A secondary outcome of the research is that distinct categories of audit engagement partner are identified, termed the crusader, the safe pair of hands, the accommodator and the truster

    Nonstationary westward translation of nonlinear frontal warm-core eddies

    Get PDF
    For the first time, an analytical theory and a very high-resolution, frontal numerical model, both based on the unsteady, nonlinear, reduced-gravity shallow water equations on a beta plane, have been used to investigate aspects of the migration of homogeneous surface, frontal warm-core eddies on a beta plane. Under the assumption that, initially, such vortices are surface circular anticyclones of paraboloidal shape and having both radial and azimuthal velocities that are linearly dependent on the radial coordinate (i.e., circular pulsons of the first order), approximate analytical expressions are found that describe the nonstationary trajectories of their centers of mass for an initial stage as well as for a mature stage of their westward migration. In particular, near-inertial oscillations are evident in the initial migration stage, whose amplitude linearly increases with time, as a result of the unbalanced vortex initial state on a beta plane. Such an initial amplification of the vortex oscillations is actually found in the first stage of the evolution of warm-core frontal eddies simulated numerically by means of a frontal numerical model initialized using the shape and velocity fields of circular pulsons of the first order. In the numerical simulations, this stage is followed by an adjusted, complex nonstationary state characterized by a noticeable asymmetry in the meridional component of the vortex's horizontal pressure gradient, which develops to compensate for the variations of the Coriolis parameter with latitude. Accordingly, the location of the simulated vortex's maximum depth is always found poleward of the location of the simulated vortex's center of mass. Moreover, during the adjusted stage, near-inertial oscillations emerge that largely deviate from the exactly inertial ones characterizing analytical circular pulsons: a superinertial and a subinertial oscillation in fact appear, and their frequency difference is found to be an increasing function of latitude. A comparison between vortex westward drifts simulated numerically at different latitudes for different vortex radii and pulsation strengths and the corresponding drifts obtained using existing formulas shows that, initially, the simulated vortex drifts correspond to the fastest predicted ones in many realistic cases. As time elapses, however, the development of a beta-adjusted vortex structure, together with the effects of numerical dissipation, tend to slow down the simulated vortex drift