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2,804 results on '"Plessis, P."'

202. Possibilities for Distributed Leadership in South African Schools: Policy Ambiguities and Blind Spots

Author

du Plessis, André and Heystek, Jan

Abstract

Against the background of the recently published Policy on the South African Standard for Principals, the aim of this article is to determine whether distributed leadership is catered for in the South African regulatory and policy framework. It is argued that due to the accountability demands of a fundamentally bureaucratic education system, distributed leadership with its heterarchical features will most likely not be applied by South African public school principals. In addition, the article argues that there is ambiguity in the leadership/management function principals are expected to perform. This is manifested in the existence of a policy-practice gap, conceptual (con-) fusion pertaining to the actions of school management and leadership, a managerial mind-set of education authorities and a divergence of top-down and bottom-up expectations of a principal's role. Furthermore, the post-apartheid capacity deficit and the contextual diversity of schools will require development of new attitudes, skills and knowledge by principals, staff members and district and provincial officials for distributed leadership to be a viable approach.

Published
2020
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203. The Lived Experience of Out-of-Field STEM Teachers: A Quandary for Strategising Quality Teaching in STEM?

Author

Du Plessis, Anna E.

Abstract

Strategising quality teaching in science, technology, engineering, or mathematics (STEM) domains turns focus to teachers' capacity to teach these subjects (UWIRE Text 2017) when they are not suitably qualified in them. Against the backdrop of research that claims that 75% of the fastest growing occupations will require STEM skills, this investigation provides new information about lived experiences of, and those surrounding, out-of-field teaching practices in STEM subject areas, and the implications these experiences have for teaching and learning environments (Office of the Chief Scientist 2014). The out-of-field teaching phenomenon is defined in this paper as occurring when teachers teach subjects or year levels outside their fields of qualification or expertise. The qualitative investigation applies a Gadamerian theoretical philosophy to develop in-depth understanding through the shared perceptions of educational directors, principals, and the lived experiences of teachers and parents from two countries. Leadership perceptions and the complexities involved in out-of-field teaching practices in science and related subject areas are investigated through the lens of multiple interviews, observations, and document analyses. Concluding remarks offer recommendations for educational leaders, reflections on improvement strategies and educational policies. Proposals for further research of the out-of-field teaching phenomenon's impact on STEM subject areas are offered.

Published
2020
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205. Rapid epidemic expansion of the SARS-CoV-2 Omicron variant in southern Africa

Author

Viana, Raquel, Moyo, Sikhulile, Amoako, Daniel G., Tegally, Houriiyah, Scheepers, Cathrine, Althaus, Christian L., Anyaneji, Ugochukwu J., Bester, Phillip A., Boni, Maciej F., Chand, Mohammed, Choga, Wonderful T., Colquhoun, Rachel, Davids, Michaela, Deforche, Koen, Doolabh, Deelan, du Plessis, Louis, Engelbrecht, Susan, Everatt, Josie, Giandhari, Jennifer, Giovanetti, Marta, Hardie, Diana, Hill, Verity, Hsiao, Nei-Yuan, Iranzadeh, Arash, Ismail, Arshad, Joseph, Charity, Joseph, Rageema, Koopile, Legodile, Kosakovsky Pond, Sergei L., Kraemer, Moritz U. G., Kuate-Lere, Lesego, Laguda-Akingba, Oluwakemi, Lesetedi-Mafoko, Onalethatha, Lessells, Richard J., Lockman, Shahin, Lucaci, Alexander G., Maharaj, Arisha, Mahlangu, Boitshoko, Maponga, Tongai, Mahlakwane, Kamela, Makatini, Zinhle, Marais, Gert, Maruapula, Dorcas, Masupu, Kereng, Matshaba, Mogomotsi, Mayaphi, Simnikiwe, Mbhele, Nokuzola, Mbulawa, Mpaphi B., Mendes, Adriano, Mlisana, Koleka, Mnguni, Anele, Mohale, Thabo, Moir, Monika, Moruisi, Kgomotso, Mosepele, Mosepele, Motsatsi, Gerald, Motswaledi, Modisa S., Mphoyakgosi, Thongbotho, Msomi, Nokukhanya, Mwangi, Peter N., Naidoo, Yeshnee, Ntuli, Noxolo, Nyaga, Martin, Olubayo, Lucier, Pillay, Sureshnee, Radibe, Botshelo, Ramphal, Yajna, Ramphal, Upasana, San, James E., Scott, Lesley, Shapiro, Roger, Singh, Lavanya, Smith-Lawrence, Pamela, Stevens, Wendy, Strydom, Amy, Subramoney, Kathleen, Tebeila, Naume, Tshiabuila, Derek, Tsui, Joseph, van Wyk, Stephanie, Weaver, Steven, Wibmer, Constantinos K., Wilkinson, Eduan, Wolter, Nicole, Zarebski, Alexander E., Zuze, Boitumelo, Goedhals, Dominique, Preiser, Wolfgang, Treurnicht, Florette, Venter, Marietje, Williamson, Carolyn, Pybus, Oliver G., Bhiman, Jinal, Glass, Allison, Martin, Darren P., Rambaut, Andrew, Gaseitsiwe, Simani, von Gottberg, Anne, and de Oliveira, Tulio

Published
2022
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207. The Changing Epidemiological Profile of HIV-1 Subtype B Epidemic in Ukraine.

Author

Liulchuk, Mariia, du Plessis, Louis, Fearnhill, Esther, Zadorozhna, Victoriia, Babii, Nataliia, Scherbinska, Alla, Novitsky, Vladimir, Pybus, Oliver, Faria, Nuno, and Vasylyeva, Tetyana

Subjects
B, HIV-1, Ukraine, molecular epidemiology, people who inject drugs, Bayes Theorem, Epidemics, Female, Genetic Variation, Geography, HIV Infections, HIV-1, Humans, Male, Phylogeny, RNA, Viral, Ukraine
Abstract

While HIV-1 subtype B has caused a large epidemic in the Western world, its transmission in Ukraine remains poorly understood. We assessed the genetic diversity of HIV-1 subtype B viruses circulating in Ukraine, characterized the transmission group structure, and estimated key evolutionary and epidemiological parameters. We analyzed 120 HIV-1 subtype B pol sequences (including 46 newly generated) sampled from patients residing in 11 regions of Ukraine between 2002 and 2017. Phylogenies were estimated using maximum likelihood and Bayesian phylogenetic methods. A Bayesian molecular clock coalescent analysis was used to estimate effective population size dynamics and date the most recent common ancestors of identified clades. A phylodynamic birth-death model was used to estimate the effective reproductive number (Re) of these clades. We identified two phylogenetically distinct predominantly Ukrainian (≥75%) clades of HIV-1 subtype B. We found no significant transmission group structure for either clade, suggesting frequent mixing among transmission groups. The estimated dates of origin of both subtype B clades were around early 1970s, similar to the introduction of HIV-1 subtype A into Ukraine. Re was estimated to be 1.42 [95% highest posterior density (HPD) 1.26-1.56] for Clade 1 and 1.69 (95% HPD 1.49-1.84) for Clade 2. Evidently, the subtype B epidemic in the country is no longer concentrated in specific geographical regions or transmission groups. The study results highlight the necessity for strengthening preventive and monitoring efforts to reduce the further spread of HIV-1 subtype B.

Published
2019

208. 10Kin1day: A Bottom-Up Neuroimaging Initiative

Author

van den Heuvel, Martijn P, Scholtens, Lianne H, van der Burgh, Hannelore K, Agosta, Federica, Alloza, Clara, Arango, Celso, Auyeung, Bonnie, Baron-Cohen, Simon, Basaia, Silvia, Benders, Manon JNL, Beyer, Frauke, Booij, Linda, Braun, Kees PJ, Filho, Geraldo Busatto, Cahn, Wiepke, Cannon, Dara M, Chaim-Avancini, Tiffany M, Chan, Sandra SM, Chen, Eric YH, Crespo-Facorro, Benedicto, Crone, Eveline A, Dannlowski, Udo, de Zwarte, Sonja MC, Dietsche, Bruno, Donohoe, Gary, Du Plessis, Stefan, Durston, Sarah, Díaz-Caneja, Covadonga M, Díaz-Zuluaga, Ana M, Emsley, Robin, Filippi, Massimo, Frodl, Thomas, Gorges, Martin, Graff, Beata, Grotegerd, Dominik, Gąsecki, Dariusz, Hall, Julie M, Holleran, Laurena, Holt, Rosemary, Hopman, Helene J, Jansen, Andreas, Janssen, Joost, Jodzio, Krzysztof, Jäncke, Lutz, Kaleda, Vasiliy G, Kassubek, Jan, Masouleh, Shahrzad Kharabian, Kircher, Tilo, Koevoets, Martijn GJC, Kostic, Vladimir S, Krug, Axel, Lawrie, Stephen M, Lebedeva, Irina S, Lee, Edwin HM, Lett, Tristram A, Lewis, Simon JG, Liem, Franziskus, Lombardo, Michael V, Lopez-Jaramillo, Carlos, Margulies, Daniel S, Markett, Sebastian, Marques, Paulo, Martínez-Zalacaín, Ignacio, McDonald, Colm, McIntosh, Andrew M, McPhilemy, Genevieve, Meinert, Susanne L, Menchón, José M, Montag, Christian, Moreira, Pedro S, Morgado, Pedro, Mothersill, David O, Mérillat, Susan, Müller, Hans-Peter, Nabulsi, Leila, Najt, Pablo, Narkiewicz, Krzysztof, Naumczyk, Patrycja, Oranje, Bob, de la Foz, Victor Ortiz-Garcia, Peper, Jiska S, Pineda, Julian A, Rasser, Paul E, Redlich, Ronny, Repple, Jonathan, Reuter, Martin, Rosa, Pedro GP, Ruigrok, Amber NV, Sabisz, Agnieszka, Schall, Ulrich, Seedat, Soraya, Serpa, Mauricio H, Skouras, Stavros, Soriano-Mas, Carles, Sousa, Nuno, Szurowska, Edyta, Tomyshev, Alexander S, Tordesillas-Gutierrez, Diana, Valk, Sofie L, and van den Berg, Leonard H

Subjects
Biological Psychology, Psychology, Biomedical Imaging, Brain Disorders, Neurosciences, Neurological, MRI, connectome analysis, diffusion weighted MRI, brain, network, Clinical Sciences, Clinical sciences, Biological psychology
Abstract

We organized 10Kin1day, a pop-up scientific event with the goal to bring together neuroimaging groups from around the world to jointly analyze 10,000+ existing MRI connectivity datasets during a 3-day workshop. In this report, we describe the motivation and principles of 10Kin1day, together with a public release of 8,000+ MRI connectome maps of the human brain.

Published
2019

209. Genomic and epidemiological monitoring of yellow fever virus transmission potential

Author

Faria, NR, Kraemer, MUG, Hill, SC, Goes de Jesus, J, Aguiar, RS, Iani, FCM, Xavier, J, Quick, J, du Plessis, L, Dellicour, S, Thézé, J, Carvalho, RDO, Baele, G, Wu, C-H, Silveira, PP, Arruda, MB, Pereira, MA, Pereira, GC, Lourenço, J, Obolski, U, Abade, L, Vasylyeva, TI, Giovanetti, M, Yi, D, Weiss, DJ, Wint, GRW, Shearer, FM, Funk, S, Nikolay, B, Fonseca, V, Adelino, TER, Oliveira, MAA, Silva, MVF, Sacchetto, L, Figueiredo, PO, Rezende, IM, Mello, EM, Said, RFC, Santos, DA, Ferraz, ML, Brito, MG, Santana, LF, Menezes, MT, Brindeiro, RM, Tanuri, A, Dos Santos, FCP, Cunha, MS, Nogueira, JS, Rocco, IM, da Costa, AC, Komninakis, SCV, Azevedo, V, Chieppe, AO, Araujo, ESM, Mendonça, MCL, Dos Santos, CC, Dos Santos, CD, Mares-Guia, AM, Nogueira, RMR, Sequeira, PC, Abreu, RG, Garcia, MHO, Abreu, AL, Okumoto, O, Kroon, EG, de Albuquerque, CFC, Lewandowski, K, Pullan, ST, Carroll, M, de Oliveira, T, Sabino, EC, Souza, RP, Suchard, MA, Lemey, P, Trindade, GS, Drumond, BP, Filippis, AMB, Loman, NJ, Cauchemez, S, Alcantara, LCJ, and Pybus, OG

Subjects
Prevention, Genetics, Emerging Infectious Diseases, Rare Diseases, Infectious Diseases, Vaccine Related, Biodefense, Aetiology, 2.2 Factors relating to the physical environment, Infection, Aedes, Age Factors, Animals, Brazil, Disease Outbreaks, Epidemiological Monitoring, Evolution, Molecular, Genomics, Humans, Phylogeny, Polymerase Chain Reaction, Risk, Sex Factors, Spatio-Temporal Analysis, Yellow Fever, Yellow fever virus, General Science & Technology
Abstract

The yellow fever virus (YFV) epidemic in Brazil is the largest in decades. The recent discovery of YFV in Brazilian Aedes species mosquitos highlights a need to monitor the risk of reestablishment of urban YFV transmission in the Americas. We use a suite of epidemiological, spatial, and genomic approaches to characterize YFV transmission. We show that the age and sex distribution of human cases is characteristic of sylvatic transmission. Analysis of YFV cases combined with genomes generated locally reveals an early phase of sylvatic YFV transmission and spatial expansion toward previously YFV-free areas, followed by a rise in viral spillover to humans in late 2016. Our results establish a framework for monitoring YFV transmission in real time that will contribute to a global strategy to eliminate future YFV epidemics.

Published
2018

210. Four-Gene Pan-African Blood Signature Predicts Progression to Tuberculosis

Author

Suliman, Sara, Thompson, Ethan G, Sutherland, Jayne, Weiner, January, Ota, Martin OC, Shankar, Smitha, Penn-Nicholson, Adam, Thiel, Bonnie, Erasmus, Mzwandile, Maertzdorf, Jeroen, Duffy, Fergal J, Hill, Philip C, Hughes, E Jane, Stanley, Kim, Downing, Katrina, Fisher, Michelle L, Valvo, Joe, Parida, Shreemanta K, van der Spuy, Gian, Tromp, Gerard, Adetifa, Ifedayo MO, Donkor, Simon, Howe, Rawleigh, Mayanja-Kizza, Harriet, Boom, W Henry, Dockrell, Hazel M, Ottenhoff, Tom HM, Hatherill, Mark, Aderem, Alan, Hanekom, Willem A, Scriba, Thomas J, Kaufmann, Stefan HE, Zak, Daniel E, Walzl, Gerhard, Black, Gillian F, Kriel, Magdalena, Du Plessis, Nelita, Nene, Nonhlanhla, Roberts, Teri, Kleynhans, Leanie, Gutschmidt, Andrea, Smith, Bronwyn, Loxton, Andre G, Chegou, Novel N, Tromp, Gerhardus, Tabb, David, Klein, Michel R, Haks, Marielle C, Franken, Kees LMC, Geluk, Annemieke, van Meijgaarden, Krista E, Joosten, Simone A, Joloba, Moses, Zalwango, Sarah, Nsereko, Mary, Okwera, Brenda, Kisingo, Hussein, Golinski, Robert, Jacobson, Marc, Dockrell, Hazel, Smith, Steven, Gorak-Stolinska, Patricia, Hur, Yun-Gyoung, Lalor, Maeve, Lee, Ji-Sook, Crampin, Amelia C, French, Neil, Ngwira, Bagrey, Ben-Smith, Anne, Watkins, Kate, Ambrose, Lyn, Simukonda, Felanji, Mvula, Hazzie, Chilongo, Femia, Saul, Jacky, Branson, Keith, Mahomed, Hassan, Bilek, Nicole, Xasa, Onke, Veldsman, Ashley, Fisher, Michelle, and Mulenga, Humphrey

Subjects
HIV/AIDS, Rare Diseases, Infectious Diseases, Tuberculosis, Clinical Research, Emerging Infectious Diseases, Prevention, Genetics, 2.1 Biological and endogenous factors, 4.2 Evaluation of markers and technologies, 4.1 Discovery and preclinical testing of markers and technologies, Aetiology, Detection, screening and diagnosis, Infection, Good Health and Well Being, GC6-74 cohort study team, The ACS cohort study team, biomarkers, gene expression, tuberculosis, Medical and Health Sciences, Respiratory System
Abstract

Rationale: Contacts of patients with tuberculosis (TB) constitute an important target population for preventive measures because they are at high risk of infection with Mycobacterium tuberculosis and progression to disease.Objectives: We investigated biosignatures with predictive ability for incident TB.Methods: In a case-control study nested within the Grand Challenges 6-74 longitudinal HIV-negative African cohort of exposed household contacts, we employed RNA sequencing, PCR, and the pair ratio algorithm in a training/test set approach. Overall, 79 progressors who developed TB between 3 and 24 months after diagnosis of index case and 328 matched nonprogressors who remained healthy during 24 months of follow-up were investigated.Measurements and Main Results: A four-transcript signature derived from samples in a South African and Gambian training set predicted progression up to two years before onset of disease in blinded test set samples from South Africa, the Gambia, and Ethiopia with little population-associated variability, and it was also validated in an external cohort of South African adolescents with latent M. tuberculosis infection. By contrast, published diagnostic or prognostic TB signatures were predicted in samples from some but not all three countries, indicating site-specific variability. Post hoc meta-analysis identified a single gene pair, C1QC/TRAV27 (complement C1q C-chain / T-cell receptor-α variable gene 27) that would consistently predict TB progression in household contacts from multiple African sites but not in infected adolescents without known recent exposure events.Conclusions: Collectively, we developed a simple whole blood-based PCR test to predict TB in recently exposed household contacts from diverse African populations. This test has potential for implementation in national TB contact investigation programs.

Published
2018

212. Genomic epidemiology of SARS-CoV-2 in a UK university identifies dynamics of transmission

Author

Aggarwal, Dinesh, Warne, Ben, Jahun, Aminu S., Hamilton, William L., Fieldman, Thomas, du Plessis, Louis, Hill, Verity, Blane, Beth, Watkins, Emmeline, Wright, Elizabeth, Hall, Grant, Ludden, Catherine, Myers, Richard, Hosmillo, Myra, Chaudhry, Yasmin, Pinckert, Malte L., Georgana, Iliana, Izuagbe, Rhys, Leek, Danielle, Nsonwu, Olisaeloka, Hughes, Gareth J., Packer, Simon, Page, Andrew J., Metaxaki, Marina, Fuller, Stewart, Weale, Gillian, Holgate, Jon, Brown, Christopher A., Howes, Rob, McFarlane, Duncan, Dougan, Gordon, Pybus, Oliver G., Angelis, Daniela De, Maxwell, Patrick H., Peacock, Sharon J., Weekes, Michael P., Illingworth, Chris, Harrison, Ewan M., Matheson, Nicholas J., and Goodfellow, Ian G.

Published
2022
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213. Correction to: Microbial function and genital inflammation in young South African women at high risk of HIV infection

Author

Alisoltani, Arghavan, Manhanzva, Monalisa T., Potgieter, Matthys, Balle, Christina, Bell, Liam, Ross, Elizabeth, Iranzadeh, Arash, du Plessis, Michelle, Radzey, Nina, McDonald, Zac, Calder, Bridget, Allali, Imane, Mulder, Nicola, Dabee, Smritee, Barnabas, Shaun, Gamieldien, Hoyam, Godzik, Adam, Blackburn, Jonathan M., Tabb, David L., Bekker, Linda-Gail, Jaspan, Heather B., Passmore, Jo-Ann S., and Masson, Lindi

Published
2022
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216. Cascade Immune Mechanisms of Protection against Mycobacterium tuberculosis (IMPAc-TB): study protocol for the Household Contact Study in the Western Cape, South Africa

Author

Hiemstra, Andriёtte M., MacDonald, Candice E., van Rensburg, Ilana C., Stanley, Kim, Maasdorp, Elizna, Mc Anda, Shirley, Tönsing, Susanne, Shaw, Jane Alexandra, Tromp, Gerard, van der Spuy, Gian D., Urdahl, Kevin B., Lewinsohn, David M., Kuivaniemi, Helena, Du Plessis, Nelita, Malherbe, Stephanus T., and Walzl, Gerhard

Published
2022
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218. Clinical severity of SARS-CoV-2 Omicron BA.4 and BA.5 lineages compared to BA.1 and Delta in South Africa

Author

Wolter, Nicole, Jassat, Waasila, Walaza, Sibongile, Welch, Richard, Moultrie, Harry, Groome, Michelle J., Amoako, Daniel Gyamfi, Everatt, Josie, Bhiman, Jinal N., Scheepers, Cathrine, Tebeila, Naume, Chiwandire, Nicola, du Plessis, Mignon, Govender, Nevashan, Ismail, Arshad, Glass, Allison, Mlisana, Koleka, Stevens, Wendy, Treurnicht, Florette K., Subramoney, Kathleen, Makatini, Zinhle, Hsiao, Nei-yuan, Parboosing, Raveen, Wadula, Jeannette, Hussey, Hannah, Davies, Mary-Ann, Boulle, Andrew, von Gottberg, Anne, and Cohen, Cheryl

Published
2022
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223. Student-Teachers' Pedagogical Beliefs: Learner-Centred or Teacher-Centred When Using ICT in the Science Classroom?

Author

André du Plessis

Abstract

This exploratory qualitative case study explored the pedagogical beliefs and classroom practice of four Post Graduate Certificate in Education (PGCE) students when they implement Information and Communication Technology (ICT) for teaching and learning, including what influences their beliefs. Data were gathered by means of a teacher belief system (TBS) tool, drawing prompts that led to individual interviews, an open-ended questionnaire, lesson plans and assessment feedback forms, short summaries of how they used the ICT resources and feedback from the method lecturer and an appointed mentor teacher. The findings suggest that there appears to be a mismatch between the participants' espoused beliefs and enacted beliefs when using ICT at this point in time. The participating student-teachers used ICT tools predominately in teacher-centred ways, yet they indicated that they held learner-centred beliefs. At the same time, this does not imply that there were no learner-centred activities during their lessons. The data seems to suggest that their exposure to teacher-centred pedagogy while being learners at school, as well as their tertiary experience could have played a role in how they taught Science. It is therefore important that lecturers model constructivist learner-centred pedagogy to students and provide opportunities for students to plan and model such practice.

Published
2016

224. Experiences of Student Support in the Distance Mode Bachelor of Nursing Science Degree at the University of Namibia

Author

Du Plessis, Carol Denise, Alexander, Lucy, Ashipala, Daniel Opotamutale, and Kamenye, Esther

Abstract

The aim of this study was to understand the way in which students experienced the support services offered by the University of Namibia's distance education unit--the Centre for External Studies. The study explored students' experiences and their perceptions of the administrative, social and academic support services provided by the University of Namibia. The research design was qualitative and exploratory with the study using focus groups and interviews for the purposes of data collection. The sample comprised forty Bachelor of Nursing Science students who were enrolled at both campuses of the university between 2005 and 2011, as well as seven staff members who were involved in the student support services. Relevant documents and interviews pertaining to the envisioned support services from the Centre for External Studies served as the basis for the evaluation of the services offered. The data were analysed using thematic content analysis. The findings from the two campuses were then compared. The findings reflected positive experiences of support from both family and lecturers, as well as positive perceptions of institutional offerings such as video conferences. However, the study also found some institutional weaknesses in terms of programme delivery such as the late delivery of study materials, which had an impact on the students' submission of assignments, and inadequate communication systems which affected the delivery of support workshops.

Published
2016

227. The constant term of tempered functions on a real spherical space

Author

Beuzart-Plessis, Raphaël, Delorme, Patrick, Krötz, Bernhard, and Souaifi, Sofiane

Subjects
Mathematics - Representation Theory
Abstract

Let $Z$ be a unimodular real spherical space. We develop a theory of constant terms for tempered functions on $Z$ which parallels the work of Harish-Chandra. The constant terms $f_I$ of an eigenfunction $f$ are parametrized by subsets $I$ of the set $S$ of spherical roots which determine the fine geometry of $Z$ at infinity. Constant terms are transitive i.e. $(f_J)_I=f_I$ for $I\subset J$, and our main result is a quantitative bound of the difference $f-f_I$, which is uniform in the parameter of the eigenfunction., Comment: Final version. 72 pages. Accepted to IMRN

Published
2017

228. Class-prior Estimation for Learning from Positive and Unlabeled Data

Author

Plessis, Marthinus C. du, Niu, Gang, and Sugiyama, Masashi

Subjects
Computer Science - Learning, Statistics - Machine Learning
Abstract

We consider the problem of estimating the class prior in an unlabeled dataset. Under the assumption that an additional labeled dataset is available, the class prior can be estimated by fitting a mixture of class-wise data distributions to the unlabeled data distribution. However, in practice, such an additional labeled dataset is often not available. In this paper, we show that, with additional samples coming only from the positive class, the class prior of the unlabeled dataset can be estimated correctly. Our key idea is to use properly penalized divergences for model fitting to cancel the error caused by the absence of negative samples. We further show that the use of the penalized $L_1$-distance gives a computationally efficient algorithm with an analytic solution. The consistency, stability, and estimation error are theoretically analyzed. Finally, we experimentally demonstrate the usefulness of the proposed method., Comment: To appear in Machine Learning

Published
2016
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229. Semi-Supervised Classification Based on Classification from Positive and Unlabeled Data

Author

Sakai, Tomoya, Plessis, Marthinus Christoffel du, Niu, Gang, and Sugiyama, Masashi

Subjects
Computer Science - Learning
Abstract

Most of the semi-supervised classification methods developed so far use unlabeled data for regularization purposes under particular distributional assumptions such as the cluster assumption. In contrast, recently developed methods of classification from positive and unlabeled data (PU classification) use unlabeled data for risk evaluation, i.e., label information is directly extracted from unlabeled data. In this paper, we extend PU classification to also incorporate negative data and propose a novel semi-supervised classification approach. We establish generalization error bounds for our novel methods and show that the bounds decrease with respect to the number of unlabeled data without the distributional assumptions that are required in existing semi-supervised classification methods. Through experiments, we demonstrate the usefulness of the proposed methods., Comment: Accepted to the 34th International Conference on Machine Learning (ICML 2017)

Published
2016

230. Theoretical Comparisons of Positive-Unlabeled Learning against Positive-Negative Learning

Author

Niu, Gang, Plessis, Marthinus Christoffel du, Sakai, Tomoya, Ma, Yao, and Sugiyama, Masashi

Subjects
Computer Science - Learning, Statistics - Machine Learning
Abstract

In PU learning, a binary classifier is trained from positive (P) and unlabeled (U) data without negative (N) data. Although N data is missing, it sometimes outperforms PN learning (i.e., ordinary supervised learning). Hitherto, neither theoretical nor experimental analysis has been given to explain this phenomenon. In this paper, we theoretically compare PU (and NU) learning against PN learning based on the upper bounds on estimation errors. We find simple conditions when PU and NU learning are likely to outperform PN learning, and we prove that, in terms of the upper bounds, either PU or NU learning (depending on the class-prior probability and the sizes of P and N data) given infinite U data will improve on PN learning. Our theoretical findings well agree with the experimental results on artificial and benchmark data even when the experimental setup does not match the theoretical assumptions exactly., Comment: NIPS 2016 camera-ready version

Published
2016

232. Development and Validation of a Novel Integrated Clinical-Genomic Risk Group Classification for Localized Prostate Cancer

Author

Spratt, Daniel E, Zhang, Jingbin, Santiago-Jiménez, María, Dess, Robert T, Davis, John W, Den, Robert B, Dicker, Adam P, Kane, Christopher J, Pollack, Alan, Stoyanova, Radka, Abdollah, Firas, Ross, Ashley E, Cole, Adam, Uchio, Edward, Randall, Josh M, Nguyen, Hao, Zhao, Shuang G, Mehra, Rohit, Glass, Andrew G, Lam, Lucia LC, Chelliserry, Jijumon, du Plessis, Marguerite, Choeurng, Voleak, Aranes, Maria, Kolisnik, Tyler, Margrave, Jennifer, Alter, Jason, Jordan, Jennifer, Buerki, Christine, Yousefi, Kasra, Haddad, Zaid, Davicioni, Elai, Trabulsi, Edouard J, Loeb, Stacy, Tewari, Ashutosh, Carroll, Peter R, Weinmann, Sheila, Schaeffer, Edward M, Klein, Eric A, Karnes, R Jeffrey, Feng, Felix Y, and Nguyen, Paul L

Subjects
Urologic Diseases, Prevention, Clinical Research, Cancer, Prostate Cancer, Genetics, Human Genome, Aging, 4.2 Evaluation of markers and technologies, Detection, screening and diagnosis, Aged, Genomics, Humans, Male, Middle Aged, Prognosis, Prostatic Neoplasms, Risk, Clinical Sciences, Oncology and Carcinogenesis, Oncology & Carcinogenesis
Abstract

Purpose It is clinically challenging to integrate genomic-classifier results that report a numeric risk of recurrence into treatment recommendations for localized prostate cancer, which are founded in the framework of risk groups. We aimed to develop a novel clinical-genomic risk grouping system that can readily be incorporated into treatment guidelines for localized prostate cancer. Materials and Methods Two multicenter cohorts (n = 991) were used for training and validation of the clinical-genomic risk groups, and two additional cohorts (n = 5,937) were used for reclassification analyses. Competing risks analysis was used to estimate the risk of distant metastasis. Time-dependent c-indices were constructed to compare clinicopathologic risk models with the clinical-genomic risk groups. Results With a median follow-up of 8 years for patients in the training cohort, 10-year distant metastasis rates for National Comprehensive Cancer Network (NCCN) low, favorable-intermediate, unfavorable-intermediate, and high-risk were 7.3%, 9.2%, 38.0%, and 39.5%, respectively. In contrast, the three-tier clinical-genomic risk groups had 10-year distant metastasis rates of 3.5%, 29.4%, and 54.6%, for low-, intermediate-, and high-risk, respectively, which were consistent in the validation cohort (0%, 25.9%, and 55.2%, respectively). C-indices for the clinical-genomic risk grouping system (0.84; 95% CI, 0.61 to 0.93) were improved over NCCN (0.73; 95% CI, 0.60 to 0.86) and Cancer of the Prostate Risk Assessment (0.74; 95% CI, 0.65 to 0.84), and 30% of patients using NCCN low/intermediate/high would be reclassified by the new three-tier system and 67% of patients would be reclassified from NCCN six-tier (very-low- to very-high-risk) by the new six-tier system. Conclusion A commercially available genomic classifier in combination with standard clinicopathologic variables can generate a simple-to-use clinical-genomic risk grouping that more accurately identifies patients at low, intermediate, and high risk for metastasis and can be easily incorporated into current guidelines to better risk-stratify patients.

Published
2018

233. A high‐resolution 3D atlas of the spectrum of tuberculous and COVID‐19 lung lesions

Author

Wells, Gordon, Glasgow, Joel N, Nargan, Kievershen, Lumamba, Kapongo, Madansein, Rajhmun, Maharaj, Kameel, Perumal, Leon Y, Matthew, Malcolm, Hunter, Robert L, Pacl, Hayden, Peabody Lever, Jacelyn E, Stanford, Denise D, Singh, Satinder P, Bajpai, Prachi, Manne, Upender, Benson, Paul V, Rowe, Steven M, le Roux, Stephan, Sigal, Alex, Tshibalanganda, Muofhe, Wells, Carlyn, du Plessis, Anton, Msimang, Mpumelelo, Naidoo, Threnesan, and Steyn, Adrie J C

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2022
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234. 30-day Morbidity and Mortality After Cholecystectomy for Benign Gallbladder Disease (AMBROSE)

Author

Wong, Geoffrey Yuet Mun, Wadhawan, Himanshu, Roth Cardoso, Victor, Bravo Merodio, Laura, Rajeev, Yashasvi, Maldonado, Ricardo David, Martinino, Alessandro, Balasubaramaniam, Vignesh, Ashraf, Aabid, Siddiqui, Adeela, Al-Shkirat, Ahmad Ghassan, Mohammed Abu-Elfatth, Ahmed, Gupta, Ajay, Alkaseek, Akram, Ouyahia, Amel, Said, Amira, Pandey, Anshuman, Kumar, Ashwani, Maqbool, Baila, Millán, Carlos Alberto, Singh, Cheena, Pantoja Pachajoa, Diana Alejandra, Adamovich, Dmitry Mikhailovich, Petracchi, Enrique, Ashraf, Fariha, Clementi, Marco, Mulita, Francesk, Marom, Gad Amram, Abdulaal, Gamaleldeen, Verras, Georgios-Ioannis, Calini, Giacomo, Moretto, Gianluigi, Elfeki, Hossam, Liang, Hui, Jalaawiy, Humam, Elzayat, Ibrahim, Das, Jayanta Kumar, Aceves-Ayala, Jose Miguel, Ahmed, Kazi T., Degrate, Luca, Aggarwal, Manisha, Omar, Mohammed Ahmed, Rais, Mounira, Elhadi, Muhammed, Sakran, Nasser, Bhojwani, Rajesh, Agarwalla, Ramesh, Kanaan, Samir, Erdene, Sarnai, Chooklin, Serge, Khuroo, Suhail, Dawani, Surrendar, Asghar, Syed Tanseer, Fung, Tak Kwan James, Omarov, Taryel, Grigorean, Valentin Titus, Boras, Zdenko, Gkoutos, Georgios V., Singhal, Rishi, Mahawar, Kamal, Group:, TUGSS Multinational Audit Steering, Madhok, Brij, Graham, Yitka, Donohoe, Claire, Reira, Manel, Wadhawan, Himanshu, Vish, YKS, Jain, Rajesh, Elhadi, Muhammed, Popat, Sunil, Boddy, Alex, Jain, Vikas, Singhal, Rishi, Mahawar, Kamal, Coordinators:, TUGSS Multinational Audit Study, Martinino, Alessandro, Said, Amira, Marques, Cláudia Neves, Wazir, Ishaan, Pereira, Juan Pablo Scarano, Abouelazayem, Mohamed, Viswanath, Nakul, Sarodaya, Varun, Bala, Vignesh, Coordinators:, TUGSS Multinational Audit National, Homayoon, Roshan, Dogjani, Agron, Tidjane, Anisse, Antozzi, Luciano, Hong, Joshua, Omarov, Taryel, Dash, Anuj Kanti, Chokshi, Aishwarya, Wietzycoski, Cacio Ricardo, Petkov, Plamen, Mbonicura, Jean Claude, Yang, Wah, Zuluaga, Mauricio, Kraljik, Darko, Lincango Naranjo, Eddy P., Elghadban, Hosam Mohamed, Diaz, Angel, Gerogiannis, Ioannis, Mohammed, Adnan, Lazaros, Lazarou, Mulita, Francesk, Bhasker, Aparna Govil, Kermansaravi, Mohammad, Mahdi, Ahmed Salah, Kayyal, Mohd Yasser, Sakran, Nasser, Frattini, Francesco, Alabdallah, Nadeem Bilal, Sylvester, Kimutai Ronoh, Abdelhamid, Ibrahim, EL Fawal, Mohamad Hayssam, Allawgalli, Aiman Nuri, Dulskas, Audrius, Voon, Kelvin, Caruana, Clifford, Ballesteros, Guillermo Ponce De Leon, Erdene, Sarnai, Ouadii, Mouaqit, Nashidengo, Pueya Abdulrashid, Hazebroek, Eric, Gunawardene, Ashok, Adeyeye, Ademola, Shariff, Amir H., Liakopulos, Nicolas Juan, Toro-Huamanchumo, Carlos J., Waledziak, Maciej, Borges, Nuno, Shabbir, Azhar, Negoi, Ionut, Neimark, Aleksandr, Abouleid, Ayman, Kim, Guowei, Košir, Jurij Aleš, Ruiz Úcar, Elena, Hamid, Hytham K. S., Masri, Ruqaya, Ozmen, Mahir, Taha, Safwan, Goodman, Elliot, AL-Naggar, Hamza, Authors:, AMBROSE Audit Collaborative, Ghouali, Amin Khayreddine, Wafa, Benbrahmin, Allel, Sahli, Elkacem, Bouzenita Mohamed, Ibagherache, Razika, Ouyahia, Amel, Rais, Mounira, Seddik, El Hachemi, Kouicem, Aya Tinhinane, Abdoun, Meriem, Bouaoud, Souad, Boucenak, Kamel, Khalfa, Safia, Brahim, Bouflih, Tidjane, Anisse, Tabeti, Benali, Meharzi, Sif-El-Islem, Larbi, Hakim, Derdous, Reda, Abderaouf, Bettahar, Bouregba, Nadjette, Boukaaabeche, Fouad, Djeroua, Kamel, Sabrin, Naît Ali, Khennaf, Leila, Mesli, Smain Nabil, Ghouali, Amin Khayreddine, Aissat, Abdelnour, Pantoja Pachajoa, Diana Alejandra, Alvarez, Fernando Andrés, Milagros, Nicole Benitez, Medrano Ortiz Palombarini, Valentina Cecilia, Petracchi, Enrique, Quesada, Matias, Canullan, Carlos, Varela, Jose, Posada, Hector, Du Plessis, Cristina, Valenzuela, José Ignacio, Zurita, Melissa Andrea Fernandez, Nasim, Sana, Bowles, Thomas Alexander, Yeboah, Edward, Nair, Roshan, Felsenreich, Daniel Moritz, Omarov, Taryel, Allahverdiyeva, Nigar, Abizade, Rashad, Adamovich, Dmitry Mikhailovich, Barreiro, Thiago Alvim, Cunha, Hercio Azevedo de Vasconcelos, Castilho, Michel Victor, Ferreira, Rafael Meneguzzi Alves, Legati Junior, Ronaldo, Dias, Lorenzo, Wietzycoski, Cacio, Jacobi, Everton Walter, Julianov, Alexander, Saroglu, Azize, Yuruk, Shaban, Dimov, Rosen, Ivanov, Valentin, Dardanov, Dragomir, Yang, Wah, Wei, Zhuoqi, Liang, Hui, Millán, Carlos A., Urbina, Mónica, Cubieros, Jorge, Acosta, Shary, Jiménez, Julián, Boras, Zdenko, Vlahović, Ivan, Koronakis, Nikolaos, González, Ricardo Andrés Buenaño, Ojeda, Cintya Anabel Llerena, Aspiazu-Briones, Cristhian Gonzalo, Martinez-Espinoza, Dario Javier, Rivas-Torres, Eduardo Antonio, Lincango Naranjo, Eddy P., Aldabash, Lama, Shaat, Iman, Alsayed, Mohamed Moneer Abulfotooh, Bali, Eslam, Ayoub, Mohamed Abdel Maksoud, Mohamed, Mohamed, AL Sayed, Mohamed, Elshinnawy, Azza Mohamed Gaber, Tayiawi, Mosaab, Abu-Elfatth, Ahmed Mohammed, Mohamed, Ahmed Emadelden, Elzayat, Ibrahim, Hassan, Ahmed Abdelmotaleb Mohamed, Madany, Mohie El-Din Mostafa, EL-Kassas, Mohamed, Omar, Wael, Tawheed, Ahmed, Elfeki, Hossam, Shalaby, Mostafa, Sakr, Ahmad, Elghrieb, Ahmed Ezzat, Warda, Hisham Hazem, Sadek, Mirna, Mostafa, Mohamed, Elghadban, Hosam, Awad, Selmy, Madany, Mohie El-Din Mostafa, Maghraby, Ahmed Mostafa, Saleem, Abd-El-Aal Ali, Mahmoud, Ahmed Gaber, Madany, Mohie El-Din Mostafa, Maghraby, Ahmed Mostafa, Saleem, Abd-El-Aal Ali, Mahmoud, Ahmed Gaber, Gebril, Mahmoud, Omar, Mohammed Ahmed, Safy, Ahmed Mohamed, Saada, Ahmed, Mohamed Ads, Alaa, Diaz, Angel, Gutiérrez, Emmanuel, Salinas, Hanton, Zimmermann, Perrine, Rhaiem, Rami, Kianmanesh, Reza, Efthymiou, Evripidis, Konstantinidis, Sergios, Drogouti, Maria, Katsourakis, Anastasios, Papadoliopoulou, Maria, Michalopoulos, Nikolaos V., Sidiropoulos, Theodoros A., Kokoropoulos, Panagiotis, Ioannidis, Argyrios, Konstantinidis, Michael, Charalampakis, Vasileios, Sotiropoulou, Maria, Pantelis, Athanasios G., Kapiris, Stylianos, Tsiampas, Ioannis, Tseliou, Vasiliki, Paspala, Anna, Nastos, Constantinos, Ioannidis, Orestis, Symeonidis, Savvas, Anestiadou, Elissavet, Zapsalis, Konstantinos, Machairas, Nikolaos, Keramida, Myrto D., Dorovinis, Panagiotis, Kyakalos, Stylianos, Stavratis, Fotios, Papadopoulos, Aristeidis, Manioti, Eleni, Mouzakis, Odysseas, Nikolaou, Vassiliki, Barkolias, Evangelos, Mulita, Francesk, Verras, Georgios-Ioannis, Vasileios, Mousafeiris, Triantafyllou, Alexandra, Triantafyllou, Tania, Matthaiou, Georgia, Frountzas, Maximos, Toutouzas, Konstantinos G., Tampaki, Ekaterini Christina, Bellou, Olga, Papazacharias, Christos, Moris, Dimitrios, Felekouras, Evangelos, Stamou, Konstantinos, Tsiotos, Gregory, Fanidou, Domna, Drakos, Panagiotis Alexandros, Schizas, Dimitrios, Syllaios, Athanasios, Vailas, Michail, Georgiadou, Despoina, Zampitis, Nikolaos, Marinis, Athanasios, Stefou, Fotini, Melachroinopoulos, Nikolaos, Papaconstantinou, Dimitrios, Dellaportas, Dionysios, Lykoudis, Panagis, Lasithiotakis, Konstantinos, Magouliotis, Dimitrios, Zacharoulis, Dimitris, Laliotis, Aggelos, Gkionis, Ioannis, Baksi, Aditya, Lodha, Mahendra, Kaur, Supreet, Guha, Shanto Shila, Gupta, Amit, Rajput, Deepak, Sharma, Oshin, Huda, Farhanul, Hassan, Mohsin, Singh, Sudhir Kumar, Basu, Somprakas, Kumar, Navin, Mallik, Dhiraj, David, Lena Elizabath, Agrawal, Aditi, Pillai, Vinod G., Muralee, Meera, Haque, Parvez David, Veetil, Sreejith Kannumal, Mahajan, Amit, Jain, Deepak, Annareddy, Dinakar Reddy, Bahadur, Akshay, Bisht, Shankar Dutt, Kashmira, Mayank, Shukla, Ashish, Pandey, Anshuman, Sarda, Hitesh, Agarwalla, Ramesh, Kumar, Ashwani, Aggarwal, Manisha, Sharma, Akanksha, Paras, Alagarsamy, Raghuraman, Chokkalingam, Gangalakshmi, Bhalla, Bhavneet Singh, Ahamad, Mohammad Nafees, Ahmad, Nabeel, Oommen, Ashok Ninan, Subbarayan, Shankar, Mohan, Karthikeyan, Ashraf, Aabid, Singh, Cheena, Jaswal, Kamaljeet S., Minhas, S. S., Bains, Lovenish, Lal, Pawanindra, Das, Jayanta K., Rangad, Gordon M., Lepcha, Alfred, Kynjing, Hampher, Islam, Md Samsul, Shangpliang, Virginia, Thota, Anuroop, Pinnamraju, Karthikeya, Surapaneni, Sushama, Gurram, Ram Prakash, Reddy, Mandapati Mallikarjuna, Inteti, Kamalesh, Srikanth, V., Reddy, V. Jayapala, Parikh, Chirag, Shah, Shakshi, Chaudhary, Priya, Bhojwani, Rajesh, Gupt, Pranoy, Srimal, Ankur, Sharma, Abadhesh, Tayal, Nikhil, Ramu, Gopi, Paul, Ratnadeep, Khuroo, Suhail, Wani, Ajaz, Gusani, Rajat, Gupta, Rahul, Khanduri, Archana, Singh, Arvind, Singh, Sudhir, Pokharia, Pradip, Sharma, Ankur, Venkatappa, Sunil Kumar, Soni, Vishal, Suprapto, Bambang, Tobroni, Ahmad, Kermansaravi, Mohammad, Mousavimaleki, Ali, Eghbali, Foolad, Eghbali, Foodlad, Mashkouri, Nazanin, Jasim, Ali, Kadhim, Nammer, Jalaawiy, Humam, Sakran, Nasser, Haj, Bassel, Asadi, Ahmad, Marom, Gad Amram, Szydlo, Gabriel Shein, Demma, Jonathan Abraham, Pikarasy, Alon J., Targa, Simone, Buzzi, Gianluca, Sanna, Andrea, Currò, Giuseppe, Ammendola, Michele, Palomba, Giuseppe, Aprea, Giovanni, Capuano, Marianna, Basile, Raffaele, Argenio, Giulio, Annecchiarico, Mario, Ferraro, Daniele, Cacciatore, Chiara, Vennarecci, Giovanni, Granieri, Stefano, Bonomi, Alessandro, Frontali, Alice, Cotsoglou, Christian, Centonze, Danilo, Licciardello, Alessio, Martines, Gennaro, Tomasicchio, Giovanni, Veroux, Massimiliano, Gioco, Rossella, Distefano, Costanza, calabrò, Marcello, Caputo, Damiano, LA Vaccara, Vincenzo, Cammarata, Roberto, Farolfi, Tommaso, Degrate, Luca, adjei antwi, Stella Konadu, Brisinda, Giuseppe, Fico, Valeria, Mirco, Paolo, Biondi, Alberto, Persiani, Roberto, Giovinazzo, Francesco, Frongillo, Francesco, Evola, Giuseppe, Ferrara, Francesco, Altomare, Michele, Benuzzi, Laura, Pezzoli, Isabella, Borghi, Alessandra, Cimbanassi, Stefania, Dapri, Giovanni, Nessi, Chiara, Bianco, Federica, Uccelli, Fara Margherita Letizia, Viganò, Luca, Cordaro, Giuseppe, Dionigi, Gianlorenzo, Pino, Antonella, Morezzi, Daniele, Rizzo, Roberta, Convertini, Girolamo, Vallicelli, Carlo, Catena, Fausto, Verdi, Daunia, Mondi, Isabella, Da Lio, Corrado, Loss, Greta, D'acapito, Fabrizio, Di Pietrantonio, Daniela, Tauceri, Francesca, Ercolani, Giorgio, Bottino, Vincenzo, Bosco, Alfonso, Canfora, Alfonso, Chiappetta, Sonja, Frattini, Francesco, Rizzi, Andrea, Breda, Marta, Quaglino, Francesco, Festa, Federico, Savasta, Francesca Maria Chiara, Fiore, Alessia, Soncini, Stefania, Giordano, Alessio, Carganico, Giacomo, Cocchi, Lorenzo, Epis, Lorenzo, Moretto, Gianluigi, Casaril, Andrea, Inama, Marco, Harmony, Impellizzeri, Michail, Creciun, Alessandro, Vitali, Piazza, Martina, Basile, Guido, Pinotti, Enrico, Lapolla, Pierfrancesco, Mingoli, Andrea, Brachini, Gioia, Cirillo, Bruno, Campanelli, Michela, Gentileschi, Paolo, Rossi, Stefano, Picardi, Biagio, Savia, Eleonora, Olmi, Stefano, Uccelli, Matteo, Balla, Andrea, Lepiane, Pasquale, Saraceno, Federica, Coppola, Alessandro, Clementi, Marco, Paniccia, Federico, Grasso, Antonella, Tartaglia, Nicola, Pavone, Giovanna, Ambrosi, Antonio, Angelico, Roberta, Manzia, Tommaso Maria, Materazzo, Marco, Tisone, Giuseppe, Calini, Giacomo, Bresadola, Vittorio, Morinelli, Vittoria, Matucci-Cerinic, Pietro, Michelutti, Luca, Luzzi, Andrea-Pierre, Romairone, Emanuele, Carrabetta, Salvatore, Marzorati, Sara, Khamees, Almu'atasim, Mohammad, Alyaman Meizer, Alananzeh, Samah, AL Momani, Salam, Hijazin, Nadeen, Tarawneh, Shahd Abdulhadi, Alheji, Hazim, Alhajji, Amer, AL-Shkirat, Ahmad Ghassan, Alzoubi, Mohammad N., AL Manasra, Abdel Rahman Abdullah, Elayyan, Rasheed, Jamous, Hussam, Dardour, Mohammad, Mahafdah, Mahmoud Rawhi, AL Hammoud, Amr Ahmad, AL Quran, Mahmoud, Bosire, Friday, Zakaria, Ramy Magdy, Abdullah, Hawraa Reda, Tarboush, Abdullah, Hasan, Wisam Abraheem, Kredan, Ali Abdulnasir, Zreeg, Dafer, Muftah, Aiman, Koshlaf, Abdulmajeed, Albadi, Doaa, Abunaaja, Hayat Omar, Otman, Rema, Ben Hamida, Bahaeddin, Amnaina, Mohamed Gamal, Alhaddad, Hayfa Faraj, Shuaip, Nouran Musbah, Buderbala, Yasmeen, Hamad, Ahmad Faraj, Shames, Haitam, Bakeer, Hiba Bileid, Alkaseek, Akram, Shalabi, Laila Esnoussi, Alhadi, Aliya Salih, Ahjaaz, Mabroukah A. A., Zgheel, Usama, Abdulmoula, Zenab, Younis, Hoda, Aboubeirah, Mohammed Khayri, Binnawara, Muhannud Hassan, Arebi, Jaber Abdusslam, Alboueishi, Asraa Ali, Mohammed Ammar, Sara, Abdedalmajed Rhuma, Heba, Alsori Alharari, Mohamed, Endisha, Salahaldin Emhemmed, Ng, Chin E'ng, Lee, Yu Wei, Tay, Yen Zhir, Abdul Manan, Nurhidayah, Tajul Arifin, Mohd Syazwan, Khairul Anuar, Ariff Solihin, Kumar, Neeraj, Maiyauen, Thanesh Kumar, Zakari, Andee Dzulkarnaen, Fathi, Mohd Azem, Izhar, Mas Izzati, Awang Dahlan, Dayang Azzyati, Mokhtar, Suryati, Samsudin, Syakirah, Jaktaram Singh, Balraj Singh, Arumugam, Mohanasundram Pillai, Theevashini, Krishnasamy, Manap, Shaiful Amir, Yong, Chon Woon, Mohamed Nabil, Mohamed Nazri, Lim, Jolene Sze Huey, Voon, Kelvin, Cheng, Shi Yu, Amanullah, Muhammad Mubarak, Ahmed, Nurzarina, Lim, I. Vern, Mazlan, Mohd Rashid, Sivananthan, Asokumar, Yussra, Yusoff, Puvisny, Shanmugam Nathan, Chua, Ian Bin, Sharman, Matthew, Siow, Sze Li, Axiak, Jessica, Dowling, Jessica, Portelli, Mark, Caruana, Clifford, Beristain-Hernandez, Jose-Luis, Vazquez-Romero, Odette-Desiree, Jaime-Silva, Jessica, Cadena-Guzman, Joaquin-Homar, Aceves-Ayala, Jose Miguel, Treviño -Meza, Jasmin Marielena, Erik, Efrain-Sosa-Duran, Guzman-Águilar, Rafael, María, Zuñiga, Jose Edusrdo, Pinto Angulo, Victor Manuel, Trejo-Avila, Mario, Bozada-Gutierrez, Katya, Carrion, Christian, Gómez-Herrera, María Norma, García-Gómez, Aurora, Pimentel Melendez, Samuel Arnulfo, Bautista Martinez, Abelardo Olaf, Nuñez DE LA Rosa, Sofia, Inchaustegui Tinajero, Jose, Sordo Lima, Diego Ervey, Pérez-Soto, Rafael Humberto, Hernández-Acevedo, Juan David, Domínguez-Rosado, Ismael, Mercado-Díaz, Miguel Ángel, Sierra-Salazar, Mauricio, Pimienta, Ana, Erdene, Sarnai, Sandag, Erdene, Orgoi, Sergelen, Ochir, Chimedsuren, Batmunkh, Munkhbat, Ouazzani, Et-tayab, EL Fdili, Mostafa, Hassani Ibn Majdoub, Karim, Mazaz, Khalid, Errachidy, Meriem, Mekondjo Nashidengo, Pueya, William Quayson, Francis, Tabiri Abebrese, John, Sushmita Seibes, Sharifa, Tjipetekera, Rejoice, Lim, Yukai, Haimona, Mairarangi, Mcclean, Sophie F., Rodriguez, Shaymar Eddylena Gutierrez Rodriguez, Lopez, Acris Arnoldo Arauz Lopez, Adetoyese Adeyeye, Ademola, Nwabuoku, Emeka Stanley, Mohammed Bello, Usman, Musa Umar, Bashir, Makama, Jerry Godfrey, Aminu, Bashir, Oriakhi, Steve-nation Nehiweze, Mosanya, Arinzechukwu Obi, Omon, Henry Ehidiamen, Wuraola, Funmilola Olanike, Ishola, Adegoke, Ulasi, Ikechukwu, Irowa, Omorodion O., Agbonrofo, Peter I., Irmiya, Solomon, Ammar, Ahmed Siddique, Khattak, Shehrbano, Qureshi, Sajid, Bashir, Nida Wahid, Jalal, Hira, Kamran, Ali, Sultan, Rizwan, Fatima, Mishal, Ali, Muhammad, Farooq, Omama, Khan, Muhammad Taha Junaid, Soomro, Umar, Saleem, Amna, Khawaja, Uzzam Ahmed, Martins, Russell Seth, Dawani, Surrendar, Siddiqui, Adeela, Khan, Madiha Masood, Jafferi, Salman, Faizi, Tashaba Qaiser, Talib, Vikash, Ali, Danish, Javed, Mahad Hassan, Rasheed, M. Ahsan, Mughal, Javeed, Ijaz, Nadeem, Rehman, Imtiaz ur, Aurangzeb, Mahmud, Ahmed, Nisar, Jan, Zaka Ullah, Khan, Shahzeb, Aziz, Sarmad Saeed, Shamim Afridi, Shehzadi Ghazala, Maroof, Syed Asad, Khan, Muhammad Imaran, Zarin, Muhammad, Naz, Farah, Jan, Zakaullah, Asghar, Syed Tanseer, Ali, Sana, Azam, Saim, Jalil, Hira, Naqvi, Hasham, Ashraf, Fariha, Siddiqui, Tayyab, Murataza, Ghulam, Bari, Hassaan, Ahmed, Hassan, Jayyab, Mustafa Abu, AL-Dahdouh, Mosheer, Echeverria, R. Rainer, Mendoza, Mario Ynoue, Kisielewski, Michal, Stefura, Tomasz, Richter, Karolina, Klos, Nikola, Walędziak, Maciej, Bartosiak, Katarzyna, Komorowska, Katarzyna, Silvestre, Miguel Trigo, Santos, Cláudia, Gil, Isabela, Cardoso, Vasco Silva, Melo, Miguel Rocha, Lima, Rita, Bolota, Joana, Cotovio, Manuel, Grigorean, Valentin Titus, Stoian, Alexandru Rares, Diana Andreea, Draghici, Toma, Elena A., Lunca, Sorinel, Zarnescu, Narcis, Costea, Radu Virgil, Litvin, Andrey, Aljohani, Emad, Zaid, AbdelNasser, Shaar, Khalid, Awaf, Khalid, Zakarneh, Eman, Alowayrdi, Tumadher, Alyami, Fatimah, Alamer, Adam, Taha, Mohamed Y., Chowdhury, Sharfuddin, Alshahrani, Salem, Panyko, Arpád, Košir, Jurij Aleš, Grosek, Jan, Tomažič, Aleš, Pintar, Tadeja, Ruiz Úcar, Elena, Castro, Ernest, Sambrano, David, Garcia-Dominguez, Rafael, Tusa, Claudio, Landaluce-Olavarria, Aitor, Estraviz-Mateos, Begoña, González, Jaime, Roca, Begoña, Jayarajah, Umesh, Subasinghe, Duminda, Sivaganesh, Sivasuriya, Hamid, Hytham K. S., Galal-Eldin, Sami, Eldirdiri, Sami, Elnour, Moheyaldien, Asaad, Nada, Mohammed, Musab, Hassan, Luden Saifaldawla, Mohamed, Khalid Osman, Abdelrahman, Salma Ahmed, Alsadeg, Hajer, Ali, Ahmed Altigani Elhadi, Elsiddig Musa, Reem Abdalla, Sarih, Monira, Ismail, Samir, Ahmed, Omer Albasher Almaki, Taj Eldeen, Samaher Taj Eldeen Hassan, Elsiddig, Kamal Elzaki, Elhasan, Mohamed Elghazali Ahmed Basheer, Karamelghani, Mohammed A. F., Mohammed, Ozaz, Adam, Albushra Altayeb, Barakat, Habab Osman, Elhadi, Rawan Elnoman, Alnaji, Abdallh Abdalmajid, Mohamed, Esraa Hamza Abdel Ghani, AL Houri, Hasan, Alhouri, Ahmad, Soliman, Alnour Khmeis, AL Ahmad, Mohamad, Kayali, Ahmad Amir, Nasani, Mohannad, Nerabani, Yaman, Ashkar, Eman, Sawas, Mohamad Nabhan, Aldirani, Alaa N., Zahreddin, Amnah, Alasmar, Ammar M., Hasan, Lilav, Alhosen, Mohammed Alahmed, Klib, Mohamad, Rahman Hammadieh, Abdul, Chikh Salem, Mhd Tarek, Ghandour, Munir, Sara, Samer, Kara Tahhan, Nour, Albani, Nour, Alsaid, Bayan, Ahmad, Basel, Almaydaani, Mohamad, Abbas, Morhaf, Nanaa, Mohamad, Aloulou, Mohammad, Kudra Danial, Aghyad, Khaled, Ahmad, Latouf, Rama, Saeed, Diyala, Ghazal, Ahmad, Masri, Ruqaya, Hamdan, Ola, Ayoub, Kusay, Kadoura, Lama, Atli, Abd Alazeez, Zayat, Hussein, Niazi, Ammar, Dabbit, Abdallah, Dahrouj, Wissam, Alhaj, Ahmad, Dabbagh, Ezeddin, Aldaher, Mohammad, Bsata, Adel, Shahrour, Mohamad Zaher, Khusruf, M. Akram, Wali, Tayssier, Aldroubi, Mohammad Tayeb, Almoshantaf, Mohammad Badr, Alahmad, Mohammad Abdullah, Leen, Jamil, AL-Nokta, Aya, Bakri, Ashraf, Arnaout, Ahmad Yamen, Ibrahim, Hamza, Nastah, Samer, Kanaan, Samir, Rasheed, Omeed, Mohammad, Alttaher, Bokal, Zied, Gafsi, Besma, Baccar, Marwen, AMMAR, Houssem, Ermis, Ilker, Tokocin, Merve, Kabuli, Hamit Ahmet, Tokocin, Onur, Ergenç, Muhammer, Gülşen, Taygun, Erginöz, Ergin, Uludağ, Server Sezgin, Bozkir, Haktan Övül, Zengin, Kağan, Özçelik, Mehmet Faik, Zarbaliyev, Elbrus, Çağlikülekçi, Mehmet, Böler, Deniz, Aktokmakyan, Talar Vartanoglu, Peksen, Caghan, Savas, Osman Anil, Sumer, Aziz, Guldogan, Cem Emir, Ozmen, Mahir, Kaplan, Mehmet, Colak, Elif, Şanli, Ahmet Necati, Kilani, Ayoub Ibrahim, Kamer, Erdinc, Namdaroglu, Ozan, Ahmed, Fuad, Marzouk, Ahmed, Harbinson, Daniel, Abdulrahman, Hassal, Ali, Heba, Abousamra, Mohamed, Di Maggio, Francesco, Abushawaly, Amr, Badawi, Marwa, Rahman, Atiqur, Jenner, Deborah, Said, Amira, Ahmed, Kazi, Watali, Yawar, Soggiu, Fiammetta, Sheth, Hemant, Drymousis, Panagiotis, Caterson, Jessica, Mehmood, Saqib, Wadhawan, Himanshu, Strachan, David, Mcelroy, Luke, Chauhan, Munish, Morgan, Richard, Mamun, Muhammad, Tora, Mir, Shamali, Awad, ML Williamson, James, Slim, Naim, Mark, Safiya, Huppler, Lucy, Crane, Sophie, Mcgrath, Polly, Fung, James Tak Kwan, Kok, Siu Yan, Bond-Smith, Giles, Dawani, Aruna, Shamardal, Aliaa, Ahmed, Mohammed M. Madi, Obasi, Chekwas, Gala, Tanzeela, Elshaer, Ahmed Mohammed, Warner, Sian, Nathadwarawala, Pooja, Askari, Alan, Pandanaboyana, Sanjay, Thakkar, Rohan, Barbour, Fraser, Finch, Jonathan Guy, Habib, Helai, Ansong, Eric, Attard, Joseph, Aujayeb, Avinash, Gupta, Ajay, Fale, Madeleine, Gupta, Anuj, Gajdhar, Aniq, Fareed, Khaleel, Elfeky, Mohamed Abdelfattah, Ashry, Mohamed, Kaur, Mandeep, Faycal Mirghani, Shaza, Tanveer, Yousaf, Albendary, Mohamed, Bhattacharya, Pratik, Abdulaal, Gamaleldeen, Ghufran, Muhammad Ali, Ghanem, Ahmed, Leong, Darren, Mamidanna, Ravikrishna, Aamery, Amaar, Tewari, Nilanjana, Williams, Greg, Tariq, Hamza, Klair, Anjeevan Kaur, Jones, Katie, Selvachandran, Haran, Day, Arthur, Ajmani, Adesh, Parmar, Chetan, Bosch, Karen, Young, Richard, Chan, Alvina, Silva, Yashodha, Kureci, Abdulrahman, Paranyak, Mykola, Shepetko-Dombrovskii, Oleksii, Chooklin, Serge, Chuklin, Serhii, Dutka, Yaromyr, Maqbool, Baila, Gill, Ali Abdullah, Jan, Azalea, Murali, Tharani, Alhajami, Faris, Atiah, Nora, Nadeesh, Areej, and Almaqdi, Sarah

Published
2025
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235. Individual Patient-Level Meta-Analysis of the Performance of the Decipher Genomic Classifier in High-Risk Men After Prostatectomy to Predict Development of Metastatic Disease

Author

Spratt, Daniel E, Yousefi, Kasra, Deheshi, Samineh, Ross, Ashley E, Den, Robert B, Schaeffer, Edward M, Trock, Bruce J, Zhang, Jingbin, Glass, Andrew G, Dicker, Adam P, Abdollah, Firas, Zhao, Shuang G, Lam, Lucia LC, du Plessis, Marguerite, Choeurng, Voleak, Haddad, Zaid, Buerki, Christine, Davicioni, Elai, Weinmann, Sheila, Freedland, Stephen J, Klein, Eric A, Karnes, R Jeffrey, and Feng, Felix Y

Subjects
Aging, Cancer, Prevention, Aged, Biomarkers, Tumor, Follow-Up Studies, Humans, Male, Middle Aged, Multivariate Analysis, Neoplasm Grading, Neoplasm Metastasis, Nomograms, Prognosis, Prostatectomy, Prostatic Neoplasms, Risk Assessment, Risk Factors, Clinical Sciences, Oncology and Carcinogenesis, Oncology & Carcinogenesis
Abstract

Purpose To perform the first meta-analysis of the performance of the genomic classifier test, Decipher, in men with prostate cancer postprostatectomy. Methods MEDLINE, EMBASE, and the Decipher genomic resource information database were searched for published reports between 2011 and 2016 of men treated by prostatectomy that assessed the benefit of the Decipher test. Multivariable Cox proportional hazards models fit to individual patient data were performed; meta-analyses were conducted by pooling the study-specific hazard ratios (HRs) using random-effects modeling. Extent of heterogeneity between studies was determined with the I2 test. Results Five studies (975 total patients, and 855 patients with individual patient-level data) were eligible for analysis, with a median follow-up of 8 years. Of the total cohort, 60.9%, 22.6%, and 16.5% of patients were classified by Decipher as low, intermediate, and high risk, respectively. The 10-year cumulative incidence metastases rates were 5.5%, 15.0%, and 26.7% ( P < .001), respectively, for the three risk classifications. Pooling the study-specific Decipher HRs across the five studies resulted in an HR of 1.52 (95% CI, 1.39 to 1.67; I2 = 0%) per 0.1 unit. In multivariable analysis of individual patient data, adjusting for clinicopathologic variables, Decipher remained a statistically significant predictor of metastasis (HR, 1.30; 95% CI, 1.14 to 1.47; P < .001) per 0.1 unit. The C-index for 10-year distant metastasis of the clinical model alone was 0.76; this increased to 0.81 with inclusion of Decipher. Conclusion The genomic classifier test, Decipher, can independently improve prognostication of patients postprostatectomy, as well as within nearly all clinicopathologic, demographic, and treatment subgroups. Future study of how to best incorporate genomic testing in clinical decision-making and subsequent treatment recommendations is warranted.

Published
2017

236. Decolonisation and South African Psychology research 30 years after democracy

Author

Bowman, Brett, Malherbe, Nick, Suffla, Shahnaaz, Macleod, Catriona Ida, du Plessis, Ulandi, and Mogonong, Laurah

Abstract

On the occasion of 30 years of South African democracy, we reflect on the current state of Psychology research in South Africa. We conducted a situational analysis of all papers appearing in the South African Journal of Psychology(SAJP) and abstracts in PsycINFOwith the keyword ‘South Africa’ over the last 5 years and compared the results with a previous review that used the same methodology. Findings show an increase in papers using ‘hard’ science approaches and a decrease in systems-oriented theories. Assessment remains a major topic. While COVID-19 and climate change featured, there remains a lack of or low focus on several key psycho-social issues experienced by South Africans. People living in poorer provinces and young and older people are under-represented in knowledge production. Collaborations or comparisons with other African or South American countries have decreased. Positively, production is being spearheaded by South African scholars or people affiliated with South African institutions. Using a decolonising lens that foregrounds epistemic justice, we conclude that substantial work remains to be done for knowledge production in South African Psychology to fulfil the decolonising imperative of distributive epistemic justice.

Published
2024
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240. Politics in the Time of COVID

Author

Fishel, Stefanie R., Fletcher, Andrew, Krishna, Sankaran, McKnight, Utz, du Plessis, Gitte, Shomura, Chad, Valdés, Alicia, and Voelkner, Nadine

Published
2021
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242. Adaptive Behaviour Assessment System: Indigenous Australian Adaptation Model (ABAS: IAAM)

Author

du Plessis, Santie

Abstract

The study objectives were to develop, trial and evaluate a cross-cultural adaptation of the Adaptive Behavior Assessment System-Second Edition Teacher Form (ABAS-II TF) ages 5-21 for use with Indigenous Australian students ages 5-14. This study introduced a multiphase mixed-method design with semi-structured and informal interviews, school observations, and psychometric analyses of existing and new Northern Territory student data. It trained teachers to undertake psychological testing of Indigenous students. The cross-cultural adaptation was performed according to the internationally recommended methodology, using forward translation, back-translation, revision by an expert committee, and a pilot trial. The reliability was estimated through internal consistency and standard error of measurement. The validity was assessed through test content, response process, internal structure, internal consistency, age group differences, inter-correlations among adaptive domains, and correlations with other variables. A clinical validity study tested students' performance with and without special education needs. The results indicated good internal consistency for the adaptive domains and composite score (Social Adaptive Domain, alpha = 0.92; Conceptual Adaptive Domain, alpha = 0.94; Personal Adaptive Domain, alpha = 0.78; General Adaptive Composite, alpha = 0.94). The standard error of measurement indicated high test accuracy. Content-, construct-, and concurrent validity were measured. Concurrent validity evaluated the mean scores of students with and without special education needs, indicated significant variance (p<0.001). The data showed that the cross-cultural adaptation process was successful, and the adapted instrument demonstrated satisfactory psychometric properties, making it valid and reliable to use in the Indigenous context

Published
2015

243. Leadership Readiness for Flexibility and Mobility: The 4th Dimensions on Situational Leadership Styles in Educational Settings

Author

Rajbhandari, Mani Man Singh, Loock, Coert, and Du Plessis, Pierre

Abstract

In educational settings, leadership flexibility and mobility is essential factor for leadership readiness. This incorporates both factors concerning the situational needs and followership situational readiness. Leadership in education require multi facet dimensional approaches that enables the educational leaders to fill in the gaps and reduces the mismatch between the situational need, individuals teachers demands and students development. In educational settings, leadership is distributed and is everywhere that enables the educational leaders to remain proactively ready to meet all kinds of situational variations existing within and outside the educational settings. This paper produce insight for educational leadership readiness for flexibility and mobility to fill in the gaps to enrich situational leadership theory. Situational leadership theory, maintains 4 different behavioral pattern considering followers readiness of maturity level. This paper provides the 4th dimensional leadership behavioral pattern incorporating both the situational need and follower's readiness which offers 16 different leadership situational behavioral pattern in tuned with different variations in situations and followership offering the holistic realm of leadership readiness for flexibility and mobility. The 4th dimension of situational leadership enables the leaders to exhibits various different behavioral pattern at various situational leadership styles intertwined with the follower's readiness behavioral pattern connecting the leadership elasticity and producing leadership equilibrium of high and low on task and relations. Leadership readiness for flexibility and mobility is essential to contribute the multi facet dimensional approaches of leadership. This promotes leadership elasticity and equilibrium to address the contextual immediate variations.

Published
2014

244. Uncertainty for calculating transport on Titan: a probabilistic description of bimolecular diffusion parameters

Author

Plessis, Sylvain, McDougall, Damon, Mandt, Kathy, Greathouse, Thomas, and Luspay-Kuti, Adrienn

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Statistics - Computation
Abstract

Bimolecular diffusion coefficients are important parameters used by atmospheric models to calculate altitude profiles of minor constituents in an atmosphere. Unfortunately, laboratory measurements of these coefficients were never conducted at temperature conditions relevant to the atmosphere of Titan. Here we conduct a detailed uncertainty analysis of the bimolecular diffusion coefficient parameters as applied to Titan's upper atmosphere to provide a better understanding of the impact of uncertainty for this parameter on models. Because temperature and pressure conditions are much lower than the laboratory conditions in which bimolecular diffusion parameters were measured, we apply a Bayesian framework, a problem-agnostic framework, to determine parameter estimates and associated uncertainties. We solve the Bayesian calibration problem using the open-source QUESO library which also performs a propagation of uncertainties in the calibrated parameters to temperature and pressure conditions observed in Titan's upper atmosphere. Our results show that, after propagating uncertainty through the Massman model, the uncertainty in molecular diffusion is highly correlated to temperature and we observe no noticeable correlation with pressure. We propagate the calibrated molecular diffusion estimate and associated uncertainty to obtain an estimate with uncertainty due to bimolecular diffusion for the methane molar fraction as a function of altitude. Results show that the uncertainty in methane abundance due to molecular diffusion is in general small compared to eddy diffusion and the chemical kinetics description. However, methane abundance is most sensitive to uncertainty in molecular diffusion above 1200 km where the errors are nontrivial and could have important implications for scientific research based on diffusion models in this altitude range.

Published
2015
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245. Structural transition and orbital glass physics in near itinerant CoV2O4

Author

Reig-i-Plessis, D., Casavant, D., Garlea, V. O., Aczel, A. A., Feygenson, M., Neuefeind, J., Zhou, H. D., Nagler, S. E., and MacDougall, G. J.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

The ferrimagnetic spinel $\mathrm{CoV_2O_4}$ has been a topic of intense recent interest, both as a frustrated insulator with unquenched orbital degeneracy and as a near-itinerant magnet which can be driven metallic with moderate applied pressure. Here, we report on our recent neutron diffraction and inelastic scattering measurements on powders with minimal cation site disorder. Our main new result is the identification of a weak ($\frac{\Delta a}{a} \sim 10^{-4}$), first order structural phase transition at $T^*$ = 90 K, the same temperature where spin canting was seen in recent single crystal measurements. This transition is characterized by a short-range distortion of oxygen octahedral positions, and inelastic data further establish a weak $\Delta\sim 1.25 meV$ spin gap at low temperature. Together, these findings provide strong support for the local orbital picture and the existence of an orbital glass state at temperatures below $T^*$., Comment: 8 pages, 5 figures, To be published in Physical Review B

Published
2015
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246. A local trace formula for the Gan-Gross-Prasad conjecture for unitary groups: the archimedean case

Author

Beuzart-Plessis, Raphaël

Subjects
Mathematics - Representation Theory, Mathematics - Number Theory, 22E50, 11F85
Abstract

In this paper, we prove, following earlier work of Waldspurger ([Wa1], [Wa4]), a sort of local relative trace formula which is related to the local Gan-Gross-Prasad conjecture for unitary groups over a local field $F$ of characteristic zero. As a consequence, we obtain a geometric formula for certain multiplicities $m(\pi)$ appearing in this conjecture and deduce from it a weak form of the local Gan-Gross-Prasad conjecture (multiplicity one in tempered L-packets). These results were already known over $p$-adic fields and thus are only new when $F=\mathbb{R}$., Comment: Includes corrections following the referees suggestions. Index of notations added. Two chapters have been switched

Published
2015

247. Surface collective modes in the topological insulators Bi$_2$Se$_3$ and Bi$_{0.5}$Sb$_{1.5}$Te$_{3-x}$Se$_{x}$

Author

Kogar, A., Vig, S., Thaler, A., Wong, M. H., Xiao, Y., Reig-i-Plessis, D., Cho, G. Y., Valla, T., Pan, Z., Schneeloch, J., Zhong, R., Gu, G., Hughes, T. L., MacDougall, G. J., Chiang, T. -C., and Abbamonte, P.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We used low-energy, momentum-resolved inelastic electron scattering to study surface collective modes of the three-dimensional topological insulators Bi$_2$Se$_3$ and Bi$_{0.5}$Sb$_{1.5}$Te$_{3-x}$Se$_{x}$. Our goal was to identify the "spin plasmon" predicted by Raghu and co-workers [S. Raghu, et al., Phys. Rev. Lett. 104, 116401 (2010)]. Instead, we found that the primary collective mode is a surface plasmon arising from the bulk, free carrers in these materials. This excitation dominates the spectral weight in the bosonic function of the surface, $\chi "(\textbf{q},\omega)$, at THz energy scales, and is the most likely origin of a quasiparticle dispersion kink observed in previous photoemission experiments. Our study suggests that the spin plasmon may mix with this other surface mode, calling for a more nuanced understanding of optical experiments in which the spin plasmon is reported to play a role., Comment: 5 pages, 4 figures

Published
2015
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248. A short proof of the existence of supercuspidal representations for all reductive $p$-adic groups

Author

Beuzart-Plessis, Raphaël

Subjects
Mathematics - Representation Theory
Abstract

Let $G$ be a reductive $p$-adic group. We give a short proof of the fact that $G$ always admits supercuspidal complex representations. This result has already been established by A. Kret using the Deligne-Lusztig theory of representations of finite groups of Lie type. Our argument is of a different nature and is self-contained. It is based on the Harish-Chandra theory of cusp forms and it ultimately relies on the existence of elliptic maximal tori in $G$.

Published
2015
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249. Challenges and Opportunities for Women Entrepreneurs in Botswana: Revisiting the Role of Entrepreneurship Education

Author

Rudhumbu, Norman, du Plessis, E. C., and Maphosa, Cosmas

Abstract

Purpose: The purpose of this paper is to investigate challenges faced by and opportunities open to women entrepreneurs in Botswana and how entrepreneurship education can boost their knowledge and skills of doing business profitably and contribute to women empowerment. Design/methodology/approach: In total, 400 women entrepreneurs of different ages, educational levels and from trades and different geographical locations were selected using a stratified random sampling procedure to participate in the study from ten towns and cities in the country. A structured questionnaire that used a five-point Likert scale was used for data collection. One-way ANOVA, regression analysis and descriptive statistics were used as tools for data analysis. Findings: Findings showed that women entrepreneurs faced a complex web of challenges among which were access to finance, lack of training leading to lack of technical skills, lack of knowledge of sources of financing and technical support, high competition in the market, marginalisation of women and lack of knowledge of marketing strategies. The key findings were that while women entrepreneurs faced a number of challenges, the legal and regulatory environment in Botswana was highly conducive and supportive of women entrepreneurship and also that customised entrepreneurship education and training offered opportunities for women entrepreneurs to enhance their knowledge and technical skills. Research limitations/implications: The study only used a quantitative approach to collect data. It could have perhaps been more enriching if a mixed-methods approach were used to help probe the participants more. The study also only used women entrepreneurs in cities and towns. Perhaps, it could have also got some women entrepreneurs from rural areas to hear what they say. These limitations will be addressed in future studies. Practical implications: Practical implications of the study are that women entrepreneurs need more training in business entrepreneurship for them to gain more knowledge and skills; finance houses become more accommodating to women entrepreneurship they could help in the empowerment of these people as they show potential in their businesses; and if more pro-women entrepreneurship policies are developed, they could enhance the activities of women entrepreneurs. Social implications: Women can perform as much as men in business if given the necessary support. Originality/value: This study contributes to the body of knowledge on women entrepreneurship as it helped expose challenges women entrepreneurs face as well as opportunities for them to take advantage of and improve their business operations.

Published
2020
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250. Analysing Principals' Policy Perceptions of Educators' Disciplinary Procedures: Cases in Gauteng Province, South Africa

Author

Makoelle, T. M. and du Plessis, P.

Abstract

A disciplinary process in respect of educators in South African schools can be a tedious and sometimes a lengthy process. The disciplinary process has sometimes yielded positive results but there is also a concern by school leaders about the effectiveness of this policy, as in some instances results have shown the opposite. Therefore, this study analyses the perceptions of principals in respect of the policy on educator's disciplinary procedure. The study adopted a generic qualitative research design. Qualitative data was collected from a purposefully selected sample of twenty principals by means of in-depth interviews. An inductive analysis framework was used to analyse qualitative data. Among the findings was that principals seemed less confident about the effectiveness of the policy on disciplinary procedure in respect of educators. One of the recommendations then is that a policy review is necessary to deal with perceived policy flaws.

Published
2019
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