HI View of the Norma Galaxy Cluster with MeerKAT
- Authors: Mophahlane, Koketso Vincent
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/432530 , vital:72878
- Description: Studies reveal that galaxies assemble into clusters as gas-rich, active star-forming disks and eventually settle in the virialized core as quenched early-type galaxies with depleted gas. To examine environmental effects responsible for the quenched population in the cluster core, we exploit the higher sensitivity of the MeerKAT telescope to probe Hi properties of galaxies in the Norma cluster. The Norma cluster is an ideal laboratory for this study since it is a rich and massive cluster of nearby galaxies. The Hi data cube used covers a velocity range of 483 − 11, 113 km/s, with a noise rms sensitivity of 0.09 mJy/beam and an angular resolution of ∼ 14.65′′ × 9.28′′. A total of 25 reliable Hi sources were detected over the entire velocity range. The Hi detections reveal two major galaxy overdensities located at vrad ∼ 2096 − 7646 km/s and vrad ∼ 10, 000 km/s. The first is associated with the Norma cluster gravitational potential and indicates a substructure in its velocity distribution; the other is a population of background galaxies. In this work, the Norma cluster has 13 cluster members detected in Hi and 130 galaxies from optical surveys. The spatial distribution of cluster members covers a field that is 2/3 × RA, where RA = 2.02 Mpc at cz = 4871 km/s. From the spatial distribution, optical galaxies are densely populated in the central regions, while most galaxies in Hi were detected on the outskirts. From the phase-space diagram, 6 galaxies detected in Hi are found in the virialised region, while the rest of the detections are infalling for the first time. Hi detections that are not yet virialised have asymmetrical morphologies, while virialised detections have truncated gas disks. Most cluster members that were found to have asymmetrical gas disks are also Hi deficient by 0.8 − 1.2 dex but show excess SFR efficiency for the amount of Hi detected. The results demonstrate that the initial phase of galaxy-ICM interactions might be responsible for morphological transformation and enhancement of star formation activity. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2023
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- Date Issued: 2023-10-13
Natural Language Processing with machine learning for anomaly detection on system call logs
- Authors: Goosen, Christo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424699 , vital:72176
- Description: Host intrusion detection systems and machine learning have been studied for many years especially on datasets like KDD99. Current research and systems are focused on low training and processing complex problems such as system call returns, which lack the system call arguments and potential traces of exploits run against a system. With respect to malware and vulnerabilities, signatures are relied upon, and the potential for natural language processing of the resulting logs and system call traces needs further experimentation. This research looks at unstructured raw system call traces from x86_64 bit GNU Linux operating systems with natural language processing and supervised and unsupervised machine learning techniques to identify current and unseen threats. The research explores whether these tools are within the skill set of information security professionals, or require data science professionals. The research makes use of an academic and modern system call dataset from Leipzig University and applies two machine learning models based on decision trees. Random Forest as the supervised algorithm is compared to the unsupervised Isolation Forest algorithm for this research, with each experiment repeated after hyper-parameter tuning. The research finds conclusive evidence that the Isolation Forest Tree algorithm is effective, when paired with a Principal Component Analysis, in identifying anomalies in the modern Leipzig Intrusion Detection Data Set (LID-DS) dataset combined with samples of executed malware from the Virus Total Academic dataset. The base or default model parameters produce sub-optimal results, whereas using a hyper-parameter tuning technique increases the accuracy to within promising levels for anomaly and potential zero day detection. , Thesis (MSc) -- Faculty of Science, Computer Science, 2023
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- Date Issued: 2023-10-13
The effectiveness of prolonged exposure therapy for the treatment of PTSD and suicide ideation: a case study
- Authors: Mhlane, Zuziwe Gloria
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424997 , vital:72200
- Description: Post-Traumatic Stress Disorder (PTSD) is regarded as a public health burden in South Africa (SA) (Atwoli et al., 2013; Kagee, Bantjies & Saal 2017; Koenen et al.; 2017; Williams et al., 2007). According to McGowan & Kagee (2013), young adults in SA are a high-risk group of trauma. Exposure to trauma is also associated to comorbid conditions such as depression, anxiety suicidal ideation (SI) experienced by a large population (Bantjes, McGowan, Kagee & Steel, 2016). Prolonged Exposure (PE) is empirically supported and evaluated trauma therapy for PTSD (Foa, Hembree, & Rothbaum, 2007). However, there has been limited to no studies conducted to evaluate the effectiveness of PE in SA. Therefore, this study investigated whether PE is effective treatment for PTSD symptom reduction and suicide ideation in South Africa. Three participants were recruited from Focus on the Family SA (FOTF SA SA) through purposive sampling, and single-case experimental design (SCED) was utilised. PE was implemented online through zoom for 6 sessions on each client. At baseline, all the participants met the criteria for PTSD as per the Post-traumatic stress disorder symptom scale interview for DSM-5 (PSSI-5): Participant 1 (PSSI-5 - 63), Participant 2 (PSSI-5 - 53), Participant 3 (PSSI-5 - 63) and the clinical cut off score is 23. Furthermore, all participants were screened for suicide ideation (SI) using the Beck Suicide Inventory (BSI). All participants’ BSI score ranges were mild to moderate. Participants were also screened for depression using the Beck Depression Inventory second edition (BDI-II) and anxiety using the Beck Anxiety Inventory (BAI). The score ranges for both BDI-II and BAI were moderate to severe. The Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) was also used to assess general psychological distress. The CORE-OM scores for all the participants for trauma, depression and anxiety were severe. However, the risk to self/SI for all the participants was minimal. During the intervention phase, all the participants scores showed a downtrend of PTSD symptomology, as per the Post-traumatic Stress Disorder Checklist for DSM-5 (PCL-5). The PCL-5 scores went down from PCL-5 score of 58 to final session PCL-5 score of 3. The clinical cut off score is 31-33. They were also screened using the BSI, BDI and BAI and the score ranges were mild. The CORE-OM scores for trauma, anxiety, depression, and risk to self/SI were also minimal. Overall, the preliminary result of this study supports the notion that adults with symptoms of PTSD and SI had improved at the end of a brief 6-session PE intervention. The comorbid depression also showed a downtrend. , Thesis (MA) -- Faculty of Humanities, Psychology, 2023
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- Date Issued: 2023-10-13
The portrayal of migrants and liminality in Nadifa Mohamed’s Black Mamba Boy, The Orchard of Lost Souls and The Fortune Men
- Authors: Fühner, Melissa Ashleigh
- Date: 2023-10-13
- Subjects: Mohamed, Nadifa, 1981- Criticism and interpretation , Diaspora , Transnationalism in literature , Migration studies , Liminality in literature , African literature (English) History and criticism
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425056 , vital:72205
- Description: This thesis argues that the characters in Nadifa Mohamed’s oeuvre exhibit both vulnerability and agency and that their position in society oscillates as if between two poles, as they cross social and spatial boundaries. There is no existing scholarly research that focuses on child migrants in Mohamed’s texts specifically. Here, Black Mamba Boy, The Orchard of Lost Souls and The Fortune Men are analysed and compared with a central focus on the child migrant characters to examine her portrayal of conflict-induced migration and its impact on vulnerable communities. In Black Mamba Boy, Mohamed portrays Jama’s exilic journey where he leaves his homeland of Hargeisa and migrates across territorial borders in Northeast Africa to find his father. His quest brings him from Somaliland to Sudan as he walks through countries that are devastated by the war between the British and Italian colonial forces in the 1930s. As Jama attempts to cross the spatial distance between himself and his father he also treads the invisible line between life and death. Along his journey, Jama is exploited and abused by colonial troops and traumatised by the conflict he witnesses. Mohamed revisits her father’s precarious journey not to portray him as a victim but to make him “a hero, not the fighting or romantic kind but the real deal, the starved child who survives every sling and arrow that shameless fortune throws at them” (1). Thus, the text is an account of Jama’s strength as he miraculously survives the brutalities of war. Similarly, in The Orchard of Lost Souls, the child protagonist, Deqo, is a refugee with parents. She internally migrates through Hargeisa at the moment the region breaks out into the Somali Civil War. Deqo attempts to keep herself out of harm’s way as the town is destroyed by soldiers and rebel groups who have opened fire against civilians. As a female child migrant Deqo occupies a particularly vulnerable position as she navigates a space where gender-based violence is used as a method of war. Despite the dangers around her, Deqo actively seeks out safety and a path that will free her from the tightening grip of the war. The Fortune Men depicts Mahmood’s journey of migration as an adult. When he attempts to cross the border into Wales he is ostracised, abused, and dehumanised because of his difference. Jama and Deqo’s exilic journeys are compared to Mahmood’s unsuccessful migration and the children cross borders that adults cannot cross because they use their vulnerability to seek out opportunities and change their environment. This thesis is situated within the theoretical framework of transnational and diasporic literature with a specific focus on the impact of forced migration on child migrants. Through close engagement and comparison of the three primary ii texts mentioned, this thesis demonstrates the vulnerabilities and fluctuating agencies of characters to highlight their liminal positioning. , Thesis (MA) -- Faculty of Humanities, Literary Studies in English 2023
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- Date Issued: 2023-10-13
“Rwanda cannot be exorcised”: representations of the trauma of the Rwandan Genocide in selected films and novels
- Authors: Jennings, Kathleen
- Date: 2023-10-13
- Subjects: Rwandan Genocide, Rwanda, 1994 , Genocide in literature , Genocide in motion pictures , Psychic trauma , Postcolonialism , Collective memory Rwanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425067 , vital:72206
- Description: Although the Rwandan genocide (itsembabwoko in Kinyarwanda) has often been compared with the Holocaust, in terms of literary and cinematic narratives it has been largely underrepresented, with the notable exception of the release of the films Hotel Rwanda (2004) and Sometimes in April (2005), as well as novels such as Gil Courtemanche’s A Sunday at the Pool in Kigali (2003). However, although there is now a larger oeuvre of works on the subject, they are often not widely known or disseminated beyond their countries of origin. Of even greater concern is the fact that most cinematic narratives on itsembabwoko rely on Western narrative structures in their approach to storytelling. As a result, trauma in these narratives largely tends to focus on the experiences of Western protagonists or on Rwandan protagonists from a Western point of view. This tendency can be tied to the use of Western trauma theory in exploring the effects of the genocide on its witnesses and survivors, at the expense of arguably more relevant postcolonial trauma theory. This presents a problem in theorising the trauma of itsembabwoko, which occurred in a highly specific historical context involving the processes of colonization and decolonization, and in which the difficulties in unifying a population which had been split along socio-economic lines since pre-colonial times remained unresolved. Despite its shortcomings in the postcolonial African context, it would be a mistake to dismiss Yale trauma theory entirely, however, since theorists such as Cathy Caruth still provide valuable insights into the effects of trauma on both the individual and the collective. As a result, I have sought to find commonalities between the two schools of thought, so as to create a more nuanced view of itsembabwoko, its repercussions and the violence preceding it. In writing this thesis, I have selected mostly Rwandan authors, often survivors of the genocide, whose works provide an alternative view of Rwanda’s violent history to that presented in the works mentioned above. Given that the majority of the texts I focus on have been released more recently – mostly the mid-2010s – and are less well-known than their Western counterparts, they provide the opportunity to compare first-hand accounts with those that can only partially recreate the terror of anti-Tutsi violence in Rwanda. My analysis hopefully provides a new perspective on the dominant narratives which have shaped the way in which non-Rwandan (predominantly Western) audiences understand the genocide. The overall aim of this thesis, then, is to demonstrate the importance of placing the genocide and its resultant trauma in a broader historical context, with a view to establishing that it is shortsighted to ignore the impact of pre- and post-genocide trauma on the Rwandan people when discussing itsembabwoko. Though this has been achieved in socio-historical studies, such as Mahmood Mamdani’s When Victims Become Killers: Colonialism, Nativism, and the Genocide in Rwanda, very little has been produced on literary and cinematic representations of the genocide. , Thesis (MA) -- Faculty of Humanities, Literary Studies in English 2023
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- Date Issued: 2023-10-13
Identification of selective novel hits against Mycobacterium tuberculosis KasA potential allosteric sites using bioinformatics approaches
- Authors: Hare, Fadzayi Faith
- Date: 2022-10-14
- Subjects: Tuberculosis , Docking , Molecules Models , Virtual screening , Multidrug-resistant tuberculosis , Fatty acids Synthesis , Drugs Design
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362842 , vital:65367
- Description: Tuberculosis (TB) is a global health threat that has led to approximately 1.5 million deaths annually. According to the World Health Organization (WHO), TB is among the top ten deadly diseases and is the leading cause of death due to a single infectious agent. The main challenge in the effective treatment and control of TB is the ongoing emergence of resistant strains of Mycobacterium tuberculosis (Mtb) which lead to multi-drug resistant (MDR) and extensive-drug resistant (XDR) TB. Hence, the identification and characterization of novel drug targets and drugs that modulate the activity of the pathogen are an urgent priority. The current situation even necessitates the reengineering or repurposing of drugs in order to achieve effective control. The β-ketoacyl-acyl carrier protein synthase I (KasA) of Mycobacterium tuberculosis is an essential enzyme in the mycobacterial fatty acid synthesis (FAS-II) pathway and is believed to be a promising target for drug discovery in TB. It is one of the five main proteins of the FAS-II pathway and catalyzes a key condensation reaction in the synthesis of meromycolate chains, the precursors of mycolic acids involved in cell wall formation. Although this protein has been extensively studied, little research has been devoted to the allosteric inhibition of potential drug compounds. The main aim of this research was to identify the allosteric sites on the protein that could be involved in the inhibition of substrate binding activities and novel drug compounds that bind to these sites by use of in-silico approaches. The bioinformatics approaches used in this study were divided into four main objectives namely identification of KasA homolog sequences, sequence analysis and protein characterization, allosteric site search and lastly virtual screening of DrugBank compounds via molecular docking. Fifteen homolog sequences were identified from the BLASTP analysis and were derived from bacteria, fungi and mammals. In order to discover important residues and regions within the KasA proteins, sequence alignment, motif analysis and phylogenetic studies were performed using Mtb KasA as a reference. Sequence alignment revealed conserved residues in all KasA proteins that have functional importance such as the catalytic triad residues (Cys171, His311 and His345). Motif analysis identified 18 highly conserved motifs within the KasA proteins with structural and functional roles. In addition, motifs unique to the Mtb KasA protein were also identified and explored for inhibitor drug design purposes. Phylogenetic analysis of the homolog sequences showed a distinct clustering of prokaryotes and eukaryotes. A distinctive clustering was also observed for species belonging to the same genus. Since the mechanism of action of most drugs involves the active site, allosteric site search was conducted on Mtb KasA and the human homolog protein using a combination of pocket detection algorithms with the aim of identifying sites that could be utilized in allosteric modulator drug discovery. This was followed by the virtual screening of 2089 FDA approved DrugBank compounds against the entire protein surfaces of Mtb KasA and Hsmt KasA, performed via molecular docking using AutoDock Vina. Screening of the compounds was based on the binding energies, with more focus on identifying ligands that bound exclusively to the acyl-binding tunnel of Mtb KasA. This reduced the data set to 27 promising drug compounds with a relatively high binding affinity for Mtb KasA, however, further experiments need to be performed to validate this result. Among these compounds were DB08889, DB06755, DB09270, DB11226, DB00392, DB12278, DB08936, DB00781, DB13720 and DB00392, which displayed relatively low binding energies for Mtb KasA when compared to the human homolog protein. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2022
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- Date Issued: 2022-10-14