University of the Witwatersrand

R. E. Rikhotso, Mmathabo G. Sekhoto

Supplemental Digital Content is available in the text Aim: This study aimed to retrospectively analyze our 10-year experience with total alloplastic reconstruction of the temporomandibular joint prostheses. Indications and clinical outcomes were also evaluated. Methodology: This was a cross-sectional study in which 31 patients who had alloplastic total Temporomandibular Joint prosthesis implanted between 2007 and 2017 were reviewed. Objective: Outcomes (maximum mouth opening distance and occlusion), subjective outcomes (pain, diet consistency and chewing, quality of life), and complications were evaluated. Results: There were 16 females and 15 males with a mean age of 36.94 years (range 11–72 years). In total, 51 prostheses (20 bilateral, 11 unilateral) were implanted. The stock prostheses were used in 28 patients (90.32%) and only 3 (9.68%) were of custom-made type. Fifty-eight percent of patients were diagnosed with temporomandibular joint ankylosis, 22.58% had degenerative conditions, 9.68% had pathology (hemifacial microsomia, synovial chondromatosis, and osteochondroma), and 9.68% had malocclusion. The results showed that there was a significant improvement in maximum mouth opening distance (P-value < 0.0001), particularly in patients who had ankylosis. There was improvement in diet consistency (P-value < 0.0001) and quality of life (P-value 0.013). Postoperative complications ranged from facial nerve injuries (n = 4), keloids (n = 2), and heterotopic bone formation (n = 2). Conclusion: TMJ alloplasts provide satisfactory clinical and functional outcomes for patients with end-stage TMJ diseases, evidenced by overall improvement in maximum mouth opening, chewing ability and quality of life and reduction in pain. Previously operated joints and a preoperative diagnosis of ankylosis increase the risk of occurrence of complications postimplantation of total alloplastic joints.

D. Block, I. Puerari, R. Buta, R. Abraham, M. Takamiya, A. Cam, University of the Witwatersrand, South Africa Inaoe, Mexico University of Alabama, U. O. Toronto, C. G. Observatory, Usa University of Hawaii, Usa

In the near-infrared, the morphology of older star-dominated disks indicates a simple classification scheme (1) H$m$ where $m$ is the dominant harmonic, (2) a pitch angle (derived from the Fourier spectra) associated with the rate of shear A/$\omega$ in the stellar disk and (3) a `bar strength' parameter, robustly derived from the gravitational potential or torque of the bar. A spiral galaxy may present two radically different morphologies in the optical and near-infrared regime; there is no correlation between our quantitative dust penetrated tuning fork and that of Hubble. Applications of our $z\sim$0 Fourier template to the HDF are discussed using $L$ and $M$ band simulations from an 8-m NGST; the rest-wavelength IR morphology of high-$z$ galaxies should probably be a key factor in deciding the final choice of instruments for the NGST.

A. Otto, A. Bekker, A. Punzo, Johannes T. Ferreira, C. T. D. O. Statistics, University of Pretoria, Pretoria, South Africa, Department of Economics, Business, University of Catania, Catania, Italy, School of Statistics, Actuarial Science, University of the Witwatersrand, Johannesburg, D. O. Mathematics, Statistics, San Diego State University, California, United States of America

In response to the challenge of accommodating non-Gaussian behaviour in data, the shifted asymmetric Laplace (SAL) cluster-weighted model (SALCWM) is introduced as a model-based method for jointly clustering responses and random covariates that exhibit skewness. Within each cluster, the multivariate SAL distribution is assumed for both the covariates and the responses given the covariates. To mitigate the effect of possible atypical observations, a heavy-tailed extension, the contaminated SALCWM (cSALCWM), is also proposed. In addition to the SALCWM parameters, each mixture component has a parameter controlling the proportion of outliers, one controlling the proportion of leverage points, one specifying the degree of outlierness, and another specifying the degree of leverage. The cSALCWM has the added benefit that once the model parameters are estimated and the observations are assigned to components, a more refined intra-group classification in typical points, (mild) outliers, good leverage, and bad leverage points can be directly obtained. An expectation-conditional maximization algorithm is developed for efficient maximum likelihood parameter estimation under this framework. Theoretical identifiability conditions are established, and empirical results from simulation studies and validation via real-world applications demonstrate that the cSALCWM not only preserves the modelling strengths of the SALCWM but also significantly enhances outlier detection and overall inference reliability. The methodology proposed in this paper has been implemented in an \texttt{R} package, which is publicly available at https://github.com/arnootto/ALCWM.

A. Bahini, R. Neveling, P. Neumann-Cosel, J. Carter, I. Usman, P. Adsley, N. Botha, J. W. Brummer, L. Donaldson, S. Jongile, T. Khumalo, M. Latif, K. Li, P. Z. Mabika, P. T. Molema, C. Moodley, S. Olorunfunmi, P. Papka, L. Pellegri, B. Rebeiro, E. Sideras-Haddad, F. Smit, S. Triambak, M. Wiedeking, J. D. O. Physics, University of the Witwatersrand, Johannesburg, S. Africa, iThemba Laboratory for Accelerator Based Sciences, Somerset West, I. F. Kernphysik, T. U. Darmstadt, G. D. O. Physics, Stellenbosch University, Matieland Stellenbosch, South Africa Irene Joliot Curie Lab, UMR8608, IN2P3-CNRS, U. Paris, Orsay, France., D. Physics, Universityof Zululand, Richard Bay, Astronomy, U. Cape, Bellville

Inelastic $\alpha$-particle scattering at energies of a few hundred MeV and very-forward scattering angles including $0^\circ$ has been established as a tool for the study of the isoscalar giant monopole (IS0) strength distributions in nuclei. An independent investigation of the IS0 strength in nuclei across a wide mass range was performed using the $0^\circ$ facility at iThemba Laboratory for Accelerator Based Sciences (iThemba LABS), South Africa, to understand differences observed between IS0 strength distributions in previous experiments performed at the Texas A\&M University (TAMU) Cyclotron Institute, USA and the Research Center for Nuclear Physics (RCNP), Japan. The isoscalar giant monopole resonance (ISGMR) was excited in $^{58}$Ni, $^{90}$Zr, $^{120}$Sn and $^{208}$Pb using $\alpha$-particle inelastic scattering with $196$ MeV $\alpha$ beam and scattering angles $\theta_{\text{Lab}} = 0^\circ$ and $4^\circ$. The K$600$ magnetic spectrometer at iThemba LABS was used to detect and momentum analyze the inelastically scattered $\alpha$ particles. The IS0 strength distributions in the nuclei studied were deduced with the difference-of-spectra (DoS) technique including a correction factor for the $4^\circ$ data based on the decomposition of $L>0$ cross sections in previous experiments. IS0 strength distributions for $^{58}$Ni, $^{90}$Zr, $^{120}$Sn and $^{208}$Pb are extracted in the excitation-energy region $E_{\rm x} = 9 - 25$ MeV.Using correction factors extracted from the RCNP experiments, there is a fair agreement with their published IS0 results. Good agreement for IS0 strength in $^{58}$Ni is also obtained with correction factors deduced from the TAMU results, while marked differences are found for $^{90}$Zr and $^{208}$Pb.

N. Shafi, R. Morganti, T. Oosterloo, R. B. HartRAO, University of the Witwatersrand, South Africa Astron, The Netherlands

Very deep neutral hydrogen (HI) observations of the edge-on spiral galaxy NGC 3079 with the Westerbork Synthesis Radio Telescope (WSRT) are presented. The galaxy has been studied extensively in different wavelengths and is known for its several unique and complex features. However, the new data still revealed several new features and shows that the galaxy is even more complicated and interesting than previously thought. In the new data, a large stream of gas encircling the entire galaxy was discovered, while the data also show, for the first time, that not only hot gas is blown into space by the starburst/AGN, but also large amounts of cold gas, despite the high energies involved in the outflow.