Regulation of reactivated elongation in lysed cell models of teleost retinal cones by cAMP and calcium.

Teleost retinal cones elongate in the dark and contract in the light. In isolated retinas of the green sunfish Lepomis cyanellus, cone myoids undergo microtubule-dependent elongation from 5 to 45 micron. We have previously shown that cone contraction can be reactivated in motile models of cones lysed with Brij-58. Reactivated contraction is both actin and ATP dependent, activated by calcium, and inhibited by cAMP. We report here that we have obtained reactivated cone elongation in lysed models prepared by the same procedures. Reactivated elongation is ATP dependent, activated by cAMP, and inhibited by calcium. The rate of reactivated elongation is proportional to the cAMP concentration between 10 microM and 0.5 mM, but is constant between 10 microM and 1.0 mM Mg-ATP. No elongation occurs if cAMP or Mg-ATP concentration is less than or equal to 5 microM. Mg-ATP is required for both cAMP-dependent and cAMP-independent processes, suggesting that Mg-ATP is required both for a regulatory process entailing cAMP-dependent phosphorylation and for a force-producing process. Free calcium concentrations greater than or equal to 10(-7) reduce the elongation rate by 78% or more, completely inhibiting elongation at 10(-5) M. This inhibition is not due to competition from calcium-activated contraction. Cytochalasin D blocks reactivated contraction, but does not abolish calcium inhibition of reactivated elongation. Thus calcium directly affects the elongation mechanism. Calcium inhibition is calmodulin dependent. The calmodulin inhibitor trifluoperazine abolishes calcium inhibition of elongation. Furthermore, calcium blocks elongation only if present during the lysis step; subsequent calcium addition has no effect. However, if calcium plus exogenous calmodulin are subsequently added, elongation is again inhibited. Thus calcium inhibition appears to require a soluble calmodulin which is lost shortly after lysis

Crossing the Boundary: a study of the nature and extent of racism in local league cricket

Since the start of the 1993/4 football season the 'Let's Kick Racism Out of Football’ has had some success in persuading clubs and players to recognise racism in the game and act to counter it. This summer, following our own research (Long et al, 1995) the Rugby Football League and the Commission for Racial Equality launched a 13-point Action Plan for professional clubs to adopt. Within cricket 'Hit Racism for Six' (HR46) was set-up last year to act as a pressure group to stimulate discussion about racism in cricket. Issues of race and racism in sport have recently attracted considerable media attention and stimulated popular debate. Emotion has run high over the articles by Robert Henderson (1995) and Roger Bannister (Connor 1995), the continuing confrontation between Raymond Illingworth and Devon Malcolm, the Botham/Lamb v Khan court case and the trouble on the terraces at Headingley during the summer of 1996. The balance attempted by programmes in the Radio 5 series on ‘Race around the UK’ represented one attempt to encourage a more considered approach, but throughout it has been clear that there is still a shortage of substantive research on race in sport. The Carnegie National Sports Development Centre conducted a study of black and ethnic minorities in cricket in Yorkshire that focused on issues of participation and sports development. Following the success of our rugby league project, Leeds City Council were keen for us to try to explore the more sensitive issues around race and racism. While the study of rugby league had been on the professional game this study of cricket was to be of local league cricket. Within the region this is how most people experience their cricket with some 1,300 teams affiliated to the Yorkshire Cricket Association. To establish views on race and racism we sought responses from: a) the secretaries of local league clubs b) Asian, black and white players in the leagues c) league umpire

Tunable pinning of a superconducting vortex a by a magnetic vortex

The interaction between a straight vortex line in a superconducting film and a soft magnetic nanodisk in the magnetic vortex state in the presence of a magnetic field applied parallel to the film surfaces is studied theoretically. The superconductor is described by London theory and the nanodisk by the Landau-Lifshitz continuum theory of magnetism, using the approximation known as the rigid vortex model. Pinning of the vortex line by the nanodisk is found to result, predominantly, from the interaction between the vortex line and the changes in the nanodisk magnetization induced by the magnetic field of the vortex line and applied field. In the context of the rigid vortex model, these changes result from the displacement of the magnetic vortex. This displacement is calculated analytically by minimizing the energy, and the pinning potential is obtained. The applied field can tune the pinning potential by controlling the displacement of the magnetic vortex. The nanodisk magnetization curve is predicted to change in the presence of the vortex lineComment: 9 pages, 8 figures. Submitted to Phys. Rev.

Essays on the Patient-Centered Medical Home in the United States Military Health System

The Patient-Centered Medical Home has been endorsed by the primary care community as the model of the future, with hopes that it will increase quality of care and the patient and provider experience while decreasing costs. Many aspects of the implementation of the Patient-Centered Medical Home model remain unexplored. This dissertation comprises three independent studies examining Patient-Centered Medical Home implementation in the Military Health System, including (1) the effects of environmental correlates on the time to implement the model, (2) the impact of differences in implementation on preventive care quality outcomes, and (3) the effect of differences in implementation on chronic care quality outcomes. Survival analysis was utilized to analyze the effect of environment, defined as resources and governance, on how long it took Military Health System clinics to adopt the Patient-Centered Medical Home model. Clinics were assumed to have adopted the model when they achieved National Committee on Quality Assurance recognition. Differences-in-differences models were created to compare both preventive and chronic care quality outcomes in Military Health System clinics by branch of service before and after Patient-Centered Medical Home implementation. Dependent variables included Chlamydia and various cancer screenings as well as heart condition and diabetes care HEDIS metrics. Measures were drawn from Military Health Mart, a patient-level utilization database, and aggregated at the clinic level. SPSS was used to analyze the data and we considered a p-value of less than .05 as statistical significance. Our research suggests that, while the environmental correlates of resources and governance did impact the time to adoption of the Patient-Centered Medical Home model, differences in how the model was implemented had mixed results on both preventive and chronic care quality outcomes. The differences in significant measures were small. More research is needed on cost, utilization and patient/provider satisfaction to assess the impact of implementation differences

Noncommutative Toda Chains, Hankel Quasideterminants And Painlev'e II Equation

We construct solutions of an infinite Toda system and an analogue of the Painlev'e II equation over noncommutative differential division rings in terms of quasideterminants of Hankel matrices.Comment: 16 pp; final revised version, will appear in J.Phys. A, minor changes (typos corrected following the Referee's List, aknowledgements and a new reference added

The Agency Costs of Agency Capitalism: Activist Investors and the Revaluation of Governance Rights

Equity ownership in the United States no longer reflects the dispersed share ownership of the canonical Berle-Means firm. Instead, we observe the reconcentration of ownership in the hands of institutional investment intermediaries, which gives rise to what we call “the agency costs of agency capitalism.” This ownership change has occurred because of (i) political decisions to privatize the provision of retirement savings and to require funding of such provision and (ii) capital market developments that favor investment intermediaries offering low cost diversified investment vehicles. A new set of agency costs arise because in addition to divergence between the interests of record owners and the firm’s managers, there is divergence between the interests of record owners – the institutional investors – and the beneficial owners of those institutional stakes. The business model of key investment intermediaries like mutual funds, which focus on increasing assets under management through superior relative performance, undermines their incentive and competence to engage in active monitoring of portfolio company performance. Such investors will be “rationally reticent” – willing to respond to governance proposals but not to propose them. We posit that shareholder activists should be seen as playing a specialized capital market role of setting up intervention proposals for resolution by institutional investors. The effect is to potentiate institutional investor voice, to increase the value of the vote, and thereby to reduce the agency costs we have identified. We therefore argue against recent proposed regulatory changes that would undercut shareholder activists’ economic incentives by making it harder to assemble a meaningful toe-hold position in a potential target