On Becoming an African-Asian English Academic at Rhodes University

No Abstrac

Constraints on the perturbed mutual motion in Didymos due to impact-induced deformation of its primary after the DART impact

Binary near-Earth asteroid (65803) Didymos is the target of the proposed NASA Double Asteroid Redirection Test (DART), part of the Asteroid Impact & Deflection Assessment (AIDA) mission concept. In this mission, the DART spacecraft is planned to impact the secondary body of Didymos, perturbing mutual dynamics of the system. The primary body is currently rotating at a spin period close to the spin barrier of asteroids, and materials ejected from the secondary due to the DART impact are likely to reach the primary. These conditions may cause the primary to reshape, due to landslides, or internal deformation, changing the permanent gravity field. Here, we propose that if shape deformation of the primary occurs, the mutual orbit of the system would be perturbed due to a change in the gravity field. We use a numerical simulation technique based on the full two-body problem to investigate the shape effect on the mutual dynamics in Didymos after the DART impact. The results show that under constant volume, shape deformation induces strong perturbation in the mutual motion. We find that the deformation process always causes the orbital period of the system to become shorter. If surface layers with a thickness greater than ~0.4 m on the poles of the primary move down to the equatorial region due to the DART impact, a change in the orbital period of the system and in the spin period of the primary will be detected by ground-based measurement.Comment: 8 pages, 7 figures, 2 tables, accepted for publication in MNRA

Vrou is Gif: The representation of violence against women in Margie Orford’s Clare Hart novels

This article takes as its starting point that crime fiction is a public and political response to gender-based violence. Using the methods of both discourse analysis and literary analysis of the crime fiction genre, the novels of Margie Orford, internationally acclaimed crime author and patron of Rape Crisis, are examined for their representations of violence against women, and the role played by these representations in Orford’s overall feminist project in the Clare Hart series. The article also considers theories about gender-based violence which link male violence to a purported crisis in the established gender order of South Africa. An attempt is made to understand the relationship between fictionalised representations of violence and the ‘banality’ of real-life violence. Finally, Hart, Orford’s hard-boiled female detective figure, is assessed to determine whether this character constitutes a significant feminist achievement that contributes to discourses which counter gender-based violence.Keywords: South Africa; crime fiction; gender-based violence; representation; feminist detectiv

The informed consent process for anaesthesia: perspectives of elective surgical patients at Inkosi Albert Luthuli Central Hospital, Durban, South Africa

Background: Amongst state hospitals in the eThekwini municipality, obtaining informed consent for anaesthesia is often an informal interaction between the patient and anaesthetist, lacking structure and standardisation.Objectives: To evaluate the informed consent process from the patients’ perspective in an attempt to modify current practice.Methods: Competent adult patients presenting for elective surgery were presented pre- and postoperatively with structured questionnaires addressing various aspects of the consent process.Results: Of 143 included patients, only 57% of patients were given information about their anaesthetic preoperatively. With regard to complications experienced during anaesthesia, 36% of patients preferred not to be informed of any possible sequelae, while 17% wanted to be informed of all possible complications. In total, 83% of patients who had signed the surgical consent form with the surgeon thought that they had signed an anaesthetic form with the anaesthetist. Some 56% of patients felt that written consent on a specific standardised anaesthetic consent form should be introduced.Conclusion: Even though the majority of patients are being seen preoperatively by the anaesthetist, the quality of this assessment is concerning, in terms of the amount and depth of information imparted and the lack of standardisation of information given.Keywords: anaesthetic risk, bioethics, complications and anaesthesia, informed consent, patient and anaesthesi

Modification of silicon carbide fibers for use in SiC/Ti composites

The degradation of silicon carbide fibers during exposure to conditions typical of composite fabrication was investigated. The tensile strength of pristine fibers and fibers sputtered with thin metal coatings were determined before and after treatment at 870 C for one hour in vacuum. Each fiber strength distribution was related by an analytical procedure to a projected composite ultimate tensile strength (PC UTS). The results indicate that a thin aluminum diffusion barrier can yield a 150 percent increase in PC UTS over the baseline SiC/Ti system

Improved Algorithms for Radar-based Reconstruction of Asteroid Shapes

We describe our implementation of a global-parameter optimizer and Square Root Information Filter (SRIF) into the asteroid-modelling software SHAPE. We compare the performance of our new optimizer with that of the existing sequential optimizer when operating on various forms of simulated data and actual asteroid radar data. In all cases, the new implementation performs substantially better than its predecessor: it converges faster, produces shape models that are more accurate, and solves for spin axis orientations more reliably. We discuss potential future changes to improve SHAPE's fitting speed and accuracy.Comment: 12 pages, 9 figure

Capabilities of Earth-based radar facilities for near-Earth asteroid observations

We evaluated the planetary radar capabilities at Arecibo, the Goldstone 70-m DSS-14 and 34-m DSS-13 antennas, the 70-m DSS-43 antenna at Canberra, the Green Bank Telescope, and the Parkes Radio Telescope in terms of their relative sensitivities and the number of known near-Earth asteroids (NEAs) detectable per year in monostatic and bistatic configurations. In the 2015 calendar year, monostatic observations with Arecibo and DSS-14 were capable of detecting 253 and 131 NEAs respectively, with signal-to-noise ratios (SNRs) greater than 30/track. Combined, the two observatories were capable of detecting 276 NEAs. Of these, Arecibo detected 77 and Goldstone detected 32, or 30% and 24% the numbers that were possible. The two observatories detected an additional 18 and 7 NEAs respectively, with SNRs of less than 30/track. This indicates that a substantial number of potential targets are not being observed. The bistatic configuration with DSS-14 transmitting and the Green Bank Telescope receiving was capable of detecting about 195 NEAs, or ~50% more than with monostatic observations at DSS-14. Most of the detectable asteroids were targets of opportunity that were discovered less than 15 days before the end of their observing windows. About 50% of the detectable asteroids have absolute magnitudes > 25, which corresponds diameters < ~30 m.Comment: 12 pages, 7 figures, Accepted to A