2 resultados para oblique astigmatism
em QSpace: Queen's University - Canada
Resumo:
J.M. Coetzee’s novels are suffused with a pervasive, though often oblique, Holocaust awareness. Direct references to the event and to the historical era to which it belongs, subtle stylistic and thematic echoes of Holocaust writing, and the recurrent mobilization of Holocaust imagery in Coetzee’s novels all contribute to suggest the significance of the event to the author’s work and thought. Providing Coetzee with a lens through which to view the contemporary situation, both local and global, the Holocaust offers Coetzee a means by which difficult and complex questions of ethics and historiographical truth may be approached. Above all, the Holocaust and its representation contribute to Coetzee’s exploration of the dilemmas of translating the traumatic lived experience of atrocity – including, but not limited to, life in apartheid South Africa – into narrative form. Taken as a whole, Coetzee’s oeuvre initially anticipates and later responds to, in characteristically oblique fashion, the narrative project(s) facing post-apartheid South Africa as the newly-democratic nation sought to make sense of its past through a variety of means, the most important of which was the country’s Truth and Reconciliation Commission. Implicitly challenging the TRC’s findings as well as its narrative assumptions, the Coetzean oeuvre accordingly invites being read as offering a continuous and evolving counter-narrative to the TRC and its construction of a narrative of the apartheid past for the post-apartheid nation. In utilizing the Holocaust, its representations, and the reception thereof to frame his response to apartheid, Coetzee implicates both in a critique of the Western model of modernity, suggesting, in the process, the importance of reconfiguring modernity in a more ethical shape.
Resumo:
How do the magnetic fields of massive stars evolve over time? Are their gyrochronological ages consistent with ages inferred from evolutionary tracks? Why do most stars predicted to host Centrifugal Magnetospheres (CMs) display no H$\alpha$ emission? Does plasma escape from CMs via centrifugal breakout events, or by a steady-state leakage mechanism? This thesis investigates these questions via a population study with a sample of 51 magnetic early B-type stars. The longitudinal magnetic field \bz~was measured from Least Squares Deconvolution profiles extracted from high-resolution spectropolarimetric data. New rotational periods $P_{\rm rot}$ were determined for 15 stars from \bz, leaving only 3 stars for which $P_{\rm rot}$ is unknown. Projected rotational velocities \vsini~were measured from multiple spectral lines. Effective temperatures and surface gravities were measured via ionization balances and line profile fitting of H Balmer lines. Fundamental physical parameters, \bz, \vsini, and $P_{\rm rot}$ were then used to determine radii, masses, ages, dipole oblique rotator model, stellar wind, magnetospheric, and spindown parameters using a Monte Carlo approach that self-consistently calculates all parameters while accounting for all available constraints on stellar properties. Dipole magnetic field strengths $B_{\rm d}$ follow a log-normal distribution similar to that of Ap stars, and decline over time in a fashion consistent with the expected conservation of fossil magnetic flux. $P_{\rm rot}$ increases with fractional main sequence age, mass, and $B_{\rm d}$, as expected from magnetospheric braking. However, comparison of evolutionary track ages to maximum spindown ages $t_{\rm S,max}$ shows that initial rotation fractions may be far below critical for stars with $M_*>10 M_\odot$. Computing $t_{\rm S,max}$ with different mass-loss prescriptions indicates that the mass-loss rates of B-type stars are likely much lower than expected from extrapolation from O-type stars. Stars with H$\alpha$ in emission and absorption occupy distinct regions in the updated rotation-magnetic confinement diagram: H$\alpha$-bright stars are found to be younger, more rapidly rotating, and more strongly magnetized than the general population. Emission strength is sensitive both to the volume of the CM and to the mass-loss rate, favouring leakage over centrifugal breakout.