Some studies of magnetohydrodynamic oscillations of a rotating fluid

Some theoretical studies on the propagation of Rossby-MHD waves in homogeneous media and the reflection of Rossby-MHD and inertial-MHD waves at rigid boundaries are presented. The evolution of an initial Rossby-MHD disturbance on a beta-plane is studied by the method of stationary phase in two dimensions. For positive β, long wavelength magnetic modes of this wave travel eastwards and propagate in a triangular region of the beta-plane. To an observer moving with the group velocity of a particular wave, its amplitude appears to diminish with time t as a function of t(^-1).The reflection of a Rossby-MHD wave by a conducting or insulating rigid boundary generates two reflected modes, one of which may be a non-propagating wave. The wavenumbers, group velocities, magnetic/kinetic energy ratios and energy densities of the incident and reflected waves are, in general, different. For waves of planetary dimensions, an eastwards travelling magnetic mode, on reflection from a N-S boundary, is transformed entirely into a long wavelength inertial mode and a large conversion of magnetic energy into kinetic energy is observed. An inertial-MHD wave on reflection from a conducting or an insulating rigid boundary splits up into three reflected modes one of which is always a travelling magnetic mode. The wavenumbers, group velocities, magnetic to kinetic energy ratios and energy densities of the incident and reflected waves are not equal. Although, the reflection of any of these modes always generates a reflected magnetic mode, no travelling inertial modes may be generated for certain orientations of the boundary. In the long term this phenomenon will increase the share of the energy of the magnetic modes at the expense of the inertial modes

Impact of Job Complexity and Performance on CFO Compensation

Prior research suggests that Big 4 auditors provide higher quality audits by virtue of their large size. Still, the recent reforms mandated by the Sarbanes Oxley Act – by increasing client and auditor incentives for accurate reporting – may have narrowed audit quality differences across auditor groups. In this paper, we examine audit quality for Big 4 and Mid-tier auditors during 2003-06 and include clients of other smaller audit firms for comparison purposes. We examine actual audit quality (as proxied by earnings management metrics) as well as perceived audit quality (as proxied by the client- and year-specific eloading and ex ante equity risk premium metrics). We include in our analysis only those Big 4 clients for whom the Mid-tier firms are potentially viable as auditors. Relative to other smaller audit firm clients, we find Big 4 and Mid-tier audit clients to have (1) lower levels of accrual management, (2) higher levels of real earnings management, and (3) higher levels of investor-perceived accruals quality. In each case, we were unable to reject the null that Big 4 and Mid-tier audits are similar. However, we find Big 4 audit clients to have a lower client-specific ex ante equity risk premium relative to both Mid-tier and other smaller audit firm clients. Collectively, our findings indicate that in situations where a Mid-tier auditor is potentially viable, Big 4 clients could utilize a Mid-tier firm without adversely affecting audit quality. Still, the results suggest that Big 4 clients have a lower ex ante cost of equity capital which is likely related to the insurance considerations (“deep pockets”) – rather than the audit quality -- associated with having a Big 4 auditor.Auditor concentration, Audit quality, Earnings management, Cost of equity capital.

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

Current status of the multinational Arabidopsis community

The multinational Arabidopsis research community is highly collaborative and over the past thirty years these activities have been documented by the Multinational Arabidopsis Steering Committee (MASC). Here, we (a) highlight recent research advances made with the reference plant Arabidopsis thaliana; (b) provide summaries from recent reports submitted by MASC subcommittees, projects and resources associated with MASC and from MASC country representatives; and (c) initiate a call for ideas and foci for the “fourth decadal roadmap,” which will advise and coordinate the global activities of the Arabidopsis research community

Some studies of magnetohydrodynamics oscillations of a rotating fluid

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Do the Big 4 and the Second-tier firms provide audits of similar quality?

In this paper, we examine audit quality for Big 4 and Second-tier auditors during 2003-2006. We utilize the auditor's propensity to issue a going concern audit report for distressed clients as a measure of audit quality. In addition, since the purpose of an audit is to improve financial reporting quality, we utilize abnormal accruals as an observable proxy for audit quality. Further, we utilize the client- and year-specific ex ante equity risk premium as a proxy for audit quality as perceived by investors. We control for auditor self-selection bias using the matched-pairs sample approach discussed by Francis and Lennox (2008). We find weak evidence that the Big 4 have a higher propensity to issue going concern audit opinions for distressed companies. However, the level of performance-adjusted abnormal accruals for Big 4 and Second-tier audit firm clients appears to be similar. With respect to investor perceptions, we find the client-specific ex ante equity risk premium to be lower for Big 4 clients than for Second-tier audit firm clients. Overall, our findings suggest little difference in actual audit quality but a more pronounced difference in perceived audit quality. Collectively, the evidence we provide informs the current discourse on audit quality, auditor choice, and the viability of Second-tier auditors as an alternative to the Big 4.

Erratum: Environments in the outer solar system

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