A Feasibility Study on the Efficacy of Functional Near-Infrared Spectrometry (fNIRS) to Measure Prefrontal Activation in Paediatric HIV
- Zondo, Sizwe, Ferreira-Correia, Aline, Cockcroft, Kate
- Authors: Zondo, Sizwe , Ferreira-Correia, Aline , Cockcroft, Kate
- Date: 2024
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450556 , vital:74960 , xlink:href="https://www.hindawi.com/journals/js/2024/4970794/"
- Description: Human immunodeficiency virus (HIV) infection is associated with disturbed neurotransmission and aberrant cortical networks. Although advances in the imaging of brain microarchitecture following neuroHIV has added to our knowledge of structural and functional changes associated with HIV, no data exists on paediatric HIV using optical neuroimaging techniques. This study investigated the feasibility of optical neuroimaging in paediatric HIV using functional near-infrared spectrometry (fNIRS). We measured prefrontal brain activation while participants executed a sustained attention task. We specifically tested whether patients living with HIV and study controls could perform the study protocol and whether we could measure the typical fNIRS haemodynamic response associated with neuronal activity. Eighteen participants (10 HIV participants, mean age: 13.9, SD = 1.66 years; 8 controls, mean age: 14.8, SD = 1.28 years), matched for sex, grade, and socio-economic status, were included in the study. All participants completed the Stroop colour word test (SCWT). Oxygenated haemoglobin concentration and the deoxygenated haemoglobin signal were recorded from the dorsolateral prefrontal cortex and the frontopolar area (FA) using fNIRS. The control group performed significantly better in terms of reaction time on the congruent and incongruent condition (congruent: t (16) = −3.36, : incongruent: ). A pooled group analysis of the sample indicated significant activation in the DLPF and FA to the congruent condition of the SCWT (). Although cortical activation was noted in the DLPF and the FA in each of the groups when analysed independently, this neural activation did not reach statistical significance. The results show promise that fNIRS techniques are feasible for assessing prefrontal cortical activity in paediatric HIV. Future studies should seek to reduce the signal-to-noise ratio and consider inter-individual variability when measuring prefrontal activation in paediatric samples.
- Full Text:
- Date Issued: 2024
- Authors: Zondo, Sizwe , Ferreira-Correia, Aline , Cockcroft, Kate
- Date: 2024
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450556 , vital:74960 , xlink:href="https://www.hindawi.com/journals/js/2024/4970794/"
- Description: Human immunodeficiency virus (HIV) infection is associated with disturbed neurotransmission and aberrant cortical networks. Although advances in the imaging of brain microarchitecture following neuroHIV has added to our knowledge of structural and functional changes associated with HIV, no data exists on paediatric HIV using optical neuroimaging techniques. This study investigated the feasibility of optical neuroimaging in paediatric HIV using functional near-infrared spectrometry (fNIRS). We measured prefrontal brain activation while participants executed a sustained attention task. We specifically tested whether patients living with HIV and study controls could perform the study protocol and whether we could measure the typical fNIRS haemodynamic response associated with neuronal activity. Eighteen participants (10 HIV participants, mean age: 13.9, SD = 1.66 years; 8 controls, mean age: 14.8, SD = 1.28 years), matched for sex, grade, and socio-economic status, were included in the study. All participants completed the Stroop colour word test (SCWT). Oxygenated haemoglobin concentration and the deoxygenated haemoglobin signal were recorded from the dorsolateral prefrontal cortex and the frontopolar area (FA) using fNIRS. The control group performed significantly better in terms of reaction time on the congruent and incongruent condition (congruent: t (16) = −3.36, : incongruent: ). A pooled group analysis of the sample indicated significant activation in the DLPF and FA to the congruent condition of the SCWT (). Although cortical activation was noted in the DLPF and the FA in each of the groups when analysed independently, this neural activation did not reach statistical significance. The results show promise that fNIRS techniques are feasible for assessing prefrontal cortical activity in paediatric HIV. Future studies should seek to reduce the signal-to-noise ratio and consider inter-individual variability when measuring prefrontal activation in paediatric samples.
- Full Text:
- Date Issued: 2024
A framework for DNS based detection and mitigation of malware infections on a network
- Stalmans, Etienne, Irwin, Barry V W
- Authors: Stalmans, Etienne , Irwin, Barry V W
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429827 , vital:72642 , 10.1109/ISSA.2011.6027531
- Description: Modern botnet trends have lead to the use of IP and domain fast-fluxing to avoid detection and increase resilience. These techniques bypass traditional detection systems such as blacklists and intrusion detection systems. The Domain Name Service (DNS) is one of the most prevalent protocols on modern networks and is essential for the correct operation of many network activities, including botnet activity. For this reason DNS forms the ideal candidate for monitoring, detecting and mit-igating botnet activity. In this paper a system placed at the network edge is developed with the capability to detect fast-flux domains using DNS queries. Multiple domain features were examined to determine which would be most effective in the classification of domains. This is achieved using a C5.0 decision tree classifier and Bayesian statistics, with positive samples being labeled as potentially malicious and nega-tive samples as legitimate domains. The system detects malicious do-main names with a high degree of accuracy, minimising the need for blacklists. Statistical methods, namely Naive Bayesian, Bayesian, Total Variation distance and Probability distribution are applied to detect mali-cious domain names. The detection techniques are tested against sample traffic and it is shown that malicious traffic can be detected with low false positive rates.
- Full Text:
- Date Issued: 2011
- Authors: Stalmans, Etienne , Irwin, Barry V W
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429827 , vital:72642 , 10.1109/ISSA.2011.6027531
- Description: Modern botnet trends have lead to the use of IP and domain fast-fluxing to avoid detection and increase resilience. These techniques bypass traditional detection systems such as blacklists and intrusion detection systems. The Domain Name Service (DNS) is one of the most prevalent protocols on modern networks and is essential for the correct operation of many network activities, including botnet activity. For this reason DNS forms the ideal candidate for monitoring, detecting and mit-igating botnet activity. In this paper a system placed at the network edge is developed with the capability to detect fast-flux domains using DNS queries. Multiple domain features were examined to determine which would be most effective in the classification of domains. This is achieved using a C5.0 decision tree classifier and Bayesian statistics, with positive samples being labeled as potentially malicious and nega-tive samples as legitimate domains. The system detects malicious do-main names with a high degree of accuracy, minimising the need for blacklists. Statistical methods, namely Naive Bayesian, Bayesian, Total Variation distance and Probability distribution are applied to detect mali-cious domain names. The detection techniques are tested against sample traffic and it is shown that malicious traffic can be detected with low false positive rates.
- Full Text:
- Date Issued: 2011
A Framework for the Management of Operator Policies and User Preferences for Service Compositions in the IP Multimedia Subsystem
- Tsietsi, Mosiuoa, Terzoli, Alfredo, Wells, George C
- Authors: Tsietsi, Mosiuoa , Terzoli, Alfredo , Wells, George C
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430680 , vital:72708 , https://ieeexplore.ieee.org/abstract/document/6032212
- Description: The IP Multimedia Subsystem (IMS) is a telecommunication middleware platform with robust service features that enables the delivery of a wide range of services to mobile network subscribers. Network operators are encouraged to develop services from service building blocks in order to avoid redundancies by re-using existing functionality. In this environ-ment, operators must be able to control the service execution chain in order to prevent undesirable interactions from occurring between indi-vidual building blocks. It is also in their interests to provide subscribers with personalisation options so that they can modify service composi-tions and define their own preferences for how they would like their ser-vices to behave during live sessions. This paper describes a solution for these challenges that involves the storage of service information in an XDMS and allows operator staff and subscribers to manage this in-formation using the XCAP protocol. The ETSI-defined XCAP applica-tion usage named simservs was chosen to demonstrate an application usage that can be used to create service compositions in XML format. A prototype is described that uses components of the open source Mo-bicents project to verify the suitability of the design. This work is part of a larger effort aimed at modeling interaction management in the IMS through the use of a service broker that is part of an extended IMS ser-vice layer (EISL). The service broker's functional and structural architec-ture have not yet been standardised.
- Full Text:
- Date Issued: 2011
- Authors: Tsietsi, Mosiuoa , Terzoli, Alfredo , Wells, George C
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430680 , vital:72708 , https://ieeexplore.ieee.org/abstract/document/6032212
- Description: The IP Multimedia Subsystem (IMS) is a telecommunication middleware platform with robust service features that enables the delivery of a wide range of services to mobile network subscribers. Network operators are encouraged to develop services from service building blocks in order to avoid redundancies by re-using existing functionality. In this environ-ment, operators must be able to control the service execution chain in order to prevent undesirable interactions from occurring between indi-vidual building blocks. It is also in their interests to provide subscribers with personalisation options so that they can modify service composi-tions and define their own preferences for how they would like their ser-vices to behave during live sessions. This paper describes a solution for these challenges that involves the storage of service information in an XDMS and allows operator staff and subscribers to manage this in-formation using the XCAP protocol. The ETSI-defined XCAP applica-tion usage named simservs was chosen to demonstrate an application usage that can be used to create service compositions in XML format. A prototype is described that uses components of the open source Mo-bicents project to verify the suitability of the design. This work is part of a larger effort aimed at modeling interaction management in the IMS through the use of a service broker that is part of an extended IMS ser-vice layer (EISL). The service broker's functional and structural architec-ture have not yet been standardised.
- Full Text:
- Date Issued: 2011
A Genealogy of Puberty Science: Monsters, Abnormals, and Everyone Else
- Pinto, Pedro, Macleod, Catriona I
- Authors: Pinto, Pedro , Macleod, Catriona I
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/434065 , vital:73029 , ISBN 9781315142098 , https://doi.org/10.4324/9781315142098
- Description: A Genealogy of Puberty Science explores the modern invention of puberty as a scientific object. Drawing on Foucault’s genealogical analytic, Pinto and Macleod trace the birth of puberty science in the early 1800s and follow its expansion and shifting discursive frameworks over the course of two centuries. Offering a critical inquiry into the epistemological and political roots of our present pubertal complex, this book breaks the almost complete silence concerning puberty in critical theories and research about childhood and adolescence. Most strikingly, the book highlights the failure of ongoing medical debates on early puberty to address young people’s sexual and reproductive embodiment and citizenships. A Genealogy of Puberty Science will be of great interest to academics, researchers and postgraduate students in the fields of child and adolescent health research, critical psychology, developmental psychology, health psychology, feminist and gender studies, medical history, science and technology studies, and sexualities and reproduction studies.
- Full Text:
- Date Issued: 2019
- Authors: Pinto, Pedro , Macleod, Catriona I
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/434065 , vital:73029 , ISBN 9781315142098 , https://doi.org/10.4324/9781315142098
- Description: A Genealogy of Puberty Science explores the modern invention of puberty as a scientific object. Drawing on Foucault’s genealogical analytic, Pinto and Macleod trace the birth of puberty science in the early 1800s and follow its expansion and shifting discursive frameworks over the course of two centuries. Offering a critical inquiry into the epistemological and political roots of our present pubertal complex, this book breaks the almost complete silence concerning puberty in critical theories and research about childhood and adolescence. Most strikingly, the book highlights the failure of ongoing medical debates on early puberty to address young people’s sexual and reproductive embodiment and citizenships. A Genealogy of Puberty Science will be of great interest to academics, researchers and postgraduate students in the fields of child and adolescent health research, critical psychology, developmental psychology, health psychology, feminist and gender studies, medical history, science and technology studies, and sexualities and reproduction studies.
- Full Text:
- Date Issued: 2019
A generic virtual reality interaction system and its extensions using the common object request broker architecture (CORBA)
- Rorke, Michael, Bangay, Shaun D
- Authors: Rorke, Michael , Bangay, Shaun D
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432684 , vital:72892 , https://www.cs.ru.ac.za/research/Groups/vrsig/pastprojects/013interaction/paper03.pdf
- Description: The paper describes the design and implementation of an immersive Virtual Reality (VR) interaction system. The system aims to provide a flexible mechanism for programmers to implement interaction in their VR applications, making good use of all accepted practices in the field. The paper further describes how the system was extended to a multi-user system using the CORBA middleware layer.
- Full Text:
- Date Issued: 1999
- Authors: Rorke, Michael , Bangay, Shaun D
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432684 , vital:72892 , https://www.cs.ru.ac.za/research/Groups/vrsig/pastprojects/013interaction/paper03.pdf
- Description: The paper describes the design and implementation of an immersive Virtual Reality (VR) interaction system. The system aims to provide a flexible mechanism for programmers to implement interaction in their VR applications, making good use of all accepted practices in the field. The paper further describes how the system was extended to a multi-user system using the CORBA middleware layer.
- Full Text:
- Date Issued: 1999
A gold–chitosan composite with low symmetry zinc phthalocyanine for enhanced singlet oxygen generation and improved photodynamic therapy activity
- Dube, Edith, Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Dube, Edith , Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233397 , vital:50087 , xlink:href="https://doi.org/10.1039/C8NJ00801A"
- Description: Novel zinc(II) 3-(4-((3,17,23-tris(4-(benzo[d]thiazol-2-yl)phenoxy)phthalocyanine-9-yl)oxy)phenyl)propanoic acid (complex 3) was synthesised. Complex 3 was subsequently reacted with gold nanoparticles (AuNPs), chitosan (CT) and a gold–chitosan (AuCT) hybrid to form 3-AuNPs, 3-CT and 3-AuCT, respectively. The conjugates afforded a decrease in fluorescence quantum yield with a corresponding increase in the triplet and singlet quantum yields compared to complex 3. The in vitro dark cytotoxicity and photodynamic therapy activity (PDT) of complex 3 and 3-AuCT composites were investigated against epithelial breast cancer cells (MCF-7) with both the samples showing minimum dark cytotoxicity. They both accounted for a cell viability of ≥90% at a concentration of ≤59.2 μg mL−1. 3-AuCT showed better PDT activity (compared to 3 alone) with less than 50% viable cells at a concentration of ≥29.6 μg mL−1 making it potentially applicable for PDT. On the other hand, AuCT displayed some activity against cancer cells, probably due to photothermal activity since gold is a light absorber, however it had more than 50% viable cells at a concentration of ≤59.2 μg mL−1.
- Full Text:
- Date Issued: 2018
- Authors: Dube, Edith , Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233397 , vital:50087 , xlink:href="https://doi.org/10.1039/C8NJ00801A"
- Description: Novel zinc(II) 3-(4-((3,17,23-tris(4-(benzo[d]thiazol-2-yl)phenoxy)phthalocyanine-9-yl)oxy)phenyl)propanoic acid (complex 3) was synthesised. Complex 3 was subsequently reacted with gold nanoparticles (AuNPs), chitosan (CT) and a gold–chitosan (AuCT) hybrid to form 3-AuNPs, 3-CT and 3-AuCT, respectively. The conjugates afforded a decrease in fluorescence quantum yield with a corresponding increase in the triplet and singlet quantum yields compared to complex 3. The in vitro dark cytotoxicity and photodynamic therapy activity (PDT) of complex 3 and 3-AuCT composites were investigated against epithelial breast cancer cells (MCF-7) with both the samples showing minimum dark cytotoxicity. They both accounted for a cell viability of ≥90% at a concentration of ≤59.2 μg mL−1. 3-AuCT showed better PDT activity (compared to 3 alone) with less than 50% viable cells at a concentration of ≥29.6 μg mL−1 making it potentially applicable for PDT. On the other hand, AuCT displayed some activity against cancer cells, probably due to photothermal activity since gold is a light absorber, however it had more than 50% viable cells at a concentration of ≤59.2 μg mL−1.
- Full Text:
- Date Issued: 2018
A heavy-atom-free π-extended N-confused porphyrin as a photosensitizer for photodynamic therapy
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185909 , vital:44447 , xlink:href="https://doi.org/10.1039/d1nj00112d"
- Description: The synthesis and characterization of a novel 1,3-diethyl-2-thiobarbituric-acid-substituted N-confused porphyrin (NCP-TB) is reported, along with a study of its photodynamic activity against MCF-7 cells using 530 (110 mW cm−2) and 660 nm (280 mW cm−2) Thorlabs light-emitting diodes for 30 min. The singlet oxygen quantum yield for NCP-TB is 0.38 compared to 0.23 for the parent unsubstituted N-confused porphyrin (NCP) due to the presence of a sulfur atom. NCP-TB exhibits enhanced PDT activity compared to NCP at both wavelengths. A significantly lower IC50 value of 5.2 μM was obtained at 530 nm (14.7 μM at 660 nm) despite a smaller light dose, due to a large red shift of the intense B band into the green region of the spectrum. 2′,7′-Dichlorofluorescein diacetate (DCFDA) assays demonstrate that there is intracellular generation of reactive oxygen species upon exposure to light.
- Full Text:
- Date Issued: 2021
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185909 , vital:44447 , xlink:href="https://doi.org/10.1039/d1nj00112d"
- Description: The synthesis and characterization of a novel 1,3-diethyl-2-thiobarbituric-acid-substituted N-confused porphyrin (NCP-TB) is reported, along with a study of its photodynamic activity against MCF-7 cells using 530 (110 mW cm−2) and 660 nm (280 mW cm−2) Thorlabs light-emitting diodes for 30 min. The singlet oxygen quantum yield for NCP-TB is 0.38 compared to 0.23 for the parent unsubstituted N-confused porphyrin (NCP) due to the presence of a sulfur atom. NCP-TB exhibits enhanced PDT activity compared to NCP at both wavelengths. A significantly lower IC50 value of 5.2 μM was obtained at 530 nm (14.7 μM at 660 nm) despite a smaller light dose, due to a large red shift of the intense B band into the green region of the spectrum. 2′,7′-Dichlorofluorescein diacetate (DCFDA) assays demonstrate that there is intracellular generation of reactive oxygen species upon exposure to light.
- Full Text:
- Date Issued: 2021
A high-level architecture for efficient packet trace analysis on gpu co-processors
- Nottingham, Alastair, Irwin, Barry V W
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429572 , vital:72623 , 10.1109/ISSA.2013.6641052
- Description: This paper proposes a high-level architecture to support efficient, massively parallel packet classification, filtering and analysis using commodity Graphics Processing Unit (GPU) hardware. The proposed architecture aims to provide a flexible and efficient parallel packet processing and analysis framework, supporting complex programmable filtering, data mining operations, statistical analysis functions and traffic visualisation, with minimal CPU overhead. In particular, this framework aims to provide a robust set of high-speed analysis functionality, in order to dramatically reduce the time required to process and analyse extremely large network traces. This architecture derives from initial research, which has shown GPU co-processors to be effective in accelerating packet classification to up to tera-bit speeds with minimal CPU overhead, far exceeding the bandwidth capacity between standard long term storage and the GPU device. This paper provides a high-level overview of the proposed architecture and its primary components, motivated by the results of prior research in the field.
- Full Text:
- Date Issued: 2013
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429572 , vital:72623 , 10.1109/ISSA.2013.6641052
- Description: This paper proposes a high-level architecture to support efficient, massively parallel packet classification, filtering and analysis using commodity Graphics Processing Unit (GPU) hardware. The proposed architecture aims to provide a flexible and efficient parallel packet processing and analysis framework, supporting complex programmable filtering, data mining operations, statistical analysis functions and traffic visualisation, with minimal CPU overhead. In particular, this framework aims to provide a robust set of high-speed analysis functionality, in order to dramatically reduce the time required to process and analyse extremely large network traces. This architecture derives from initial research, which has shown GPU co-processors to be effective in accelerating packet classification to up to tera-bit speeds with minimal CPU overhead, far exceeding the bandwidth capacity between standard long term storage and the GPU device. This paper provides a high-level overview of the proposed architecture and its primary components, motivated by the results of prior research in the field.
- Full Text:
- Date Issued: 2013
A highly selective and sensitive pyridylazo-2-naphthol-poly (acrylic acid) functionalized electrospun nanofiber fluorescence “turn-off” chemosensory system for Ni 2+
- Adewuyi, Sheriff, Ondigo, Dezzline A, Zugle, Ruphino, Tshentu, Zenixole R, Nyokong, Tebello, Torto, Nelson
- Authors: Adewuyi, Sheriff , Ondigo, Dezzline A , Zugle, Ruphino , Tshentu, Zenixole R , Nyokong, Tebello , Torto, Nelson
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246012 , vital:51428 , xlink:href="https://doi.org/10.1039/C2AY25182E"
- Description: A fluorescent nanofiber probe for the determination of Ni2+ was developed via the electrospinning of a covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymer. Fluorescent nanofibers with diameters in the range 230–800 nm were produced with uniformly dispersed fluorophores. The excitation and emission fluorescence were at wavelengths 479 and 557 nm respectively, thereby exhibiting a good Stokes' shift. This Ni2+ probe that employs fluorescence quenching in a solid receptor–fluorophore system exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 μg mL−1 based on the Stern–Volmer mechanism. The probe achieved a detection limit (3δ/S) of 0.07 ng mL−1 and a precision, calculated as a relative standard deviation (RSD) of more than 4% (n = 8). The concentration of Ni2+ in a certified reference material (SEP-3) was found to be 0.8986 μg mL−1, which is significantly comparable with the certified value of 0.8980 μg mL−1. The accuracy of the determinations, expressed as a relative error between the certified and the observed values of certified reference groundwater was ≤0.1%. The versatility of the nanofiber probe was demonstrated by affording simple, rapid and selective detection of Ni2+ in the presence of other competing metal ions by direct analysis, without employing any further sample handling steps.
- Full Text:
- Date Issued: 2012
- Authors: Adewuyi, Sheriff , Ondigo, Dezzline A , Zugle, Ruphino , Tshentu, Zenixole R , Nyokong, Tebello , Torto, Nelson
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246012 , vital:51428 , xlink:href="https://doi.org/10.1039/C2AY25182E"
- Description: A fluorescent nanofiber probe for the determination of Ni2+ was developed via the electrospinning of a covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymer. Fluorescent nanofibers with diameters in the range 230–800 nm were produced with uniformly dispersed fluorophores. The excitation and emission fluorescence were at wavelengths 479 and 557 nm respectively, thereby exhibiting a good Stokes' shift. This Ni2+ probe that employs fluorescence quenching in a solid receptor–fluorophore system exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 μg mL−1 based on the Stern–Volmer mechanism. The probe achieved a detection limit (3δ/S) of 0.07 ng mL−1 and a precision, calculated as a relative standard deviation (RSD) of more than 4% (n = 8). The concentration of Ni2+ in a certified reference material (SEP-3) was found to be 0.8986 μg mL−1, which is significantly comparable with the certified value of 0.8980 μg mL−1. The accuracy of the determinations, expressed as a relative error between the certified and the observed values of certified reference groundwater was ≤0.1%. The versatility of the nanofiber probe was demonstrated by affording simple, rapid and selective detection of Ni2+ in the presence of other competing metal ions by direct analysis, without employing any further sample handling steps.
- Full Text:
- Date Issued: 2012
A hundred years of History at Rhodes University: some reflections on the department's centenary colloquium, September 2011 reminiscences
- Authors: Maylam, Paul
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450012 , vital:74875 , https://www.scielo.org.za/pdf/hist/v57n1/09.pdf
- Description: In 1911, W.M. Macmillan, who would become the most distinguished South Africanist historian of his generation, was appointed as the first lecturer in History (and Economics) at what was then Rhodes University College. To mark the centenary of its founding the Rhodes History Department held a two-day colloquium on 16-17 September 2011. The event brought together almost 50 current and former staff and students. Some delivered papers reflecting on the history of the department; others spoke about their present research interests. Among the participants there was a representative from every decade since the 1940s - Rodney Davenport having been a student in the department from 1943.
- Full Text:
- Date Issued: 2012
- Authors: Maylam, Paul
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450012 , vital:74875 , https://www.scielo.org.za/pdf/hist/v57n1/09.pdf
- Description: In 1911, W.M. Macmillan, who would become the most distinguished South Africanist historian of his generation, was appointed as the first lecturer in History (and Economics) at what was then Rhodes University College. To mark the centenary of its founding the Rhodes History Department held a two-day colloquium on 16-17 September 2011. The event brought together almost 50 current and former staff and students. Some delivered papers reflecting on the history of the department; others spoke about their present research interests. Among the participants there was a representative from every decade since the 1940s - Rodney Davenport having been a student in the department from 1943.
- Full Text:
- Date Issued: 2012
A kernel-driven framework for high performance internet routing simulation
- Herbert, Alan, Irwin, Barry V W
- Authors: Herbert, Alan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429585 , vital:72624 , 10.1109/ISSA.2013.6641048
- Description: The ability to provide the simulation of packets traversing an internet path is an integral part of providing realistic simulations for network training, and cyber defence exercises. This paper builds on previous work, and considers an in-kernel approach to solving the routing simulation problem. The inkernel approach is anticipated to allow the framework to be able to achieve throughput rates of 1GB/s or higher using commodity hardware. Processes that run outside the context of the kernel of most operating system require context switching to access hardware and kernel modules. This leads to considerable delays in the processes, such as network simulators, that frequently access hardware such as hard disk accesses and network packet handling. To mitigate this problem, as experienced with earlier implementations, this research looks towards implementing a kernel module to handle network routing and simulation within a UNIX based system. This would remove delays incurred from context switching and allows for direct access to the hardware components of the host.
- Full Text:
- Date Issued: 2013
- Authors: Herbert, Alan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429585 , vital:72624 , 10.1109/ISSA.2013.6641048
- Description: The ability to provide the simulation of packets traversing an internet path is an integral part of providing realistic simulations for network training, and cyber defence exercises. This paper builds on previous work, and considers an in-kernel approach to solving the routing simulation problem. The inkernel approach is anticipated to allow the framework to be able to achieve throughput rates of 1GB/s or higher using commodity hardware. Processes that run outside the context of the kernel of most operating system require context switching to access hardware and kernel modules. This leads to considerable delays in the processes, such as network simulators, that frequently access hardware such as hard disk accesses and network packet handling. To mitigate this problem, as experienced with earlier implementations, this research looks towards implementing a kernel module to handle network routing and simulation within a UNIX based system. This would remove delays incurred from context switching and allows for direct access to the hardware components of the host.
- Full Text:
- Date Issued: 2013
A laminated, emergentist view of skills ecosystems
- Ramsarup, Presha, Lotz-Sisitka, Heila, McGrath, Simon
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
- Full Text:
- Date Issued: 2022
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
- Full Text:
- Date Issued: 2022
A Landscape of Insects and Other Invertebrates, D.N. MacFadyen: book review
- Authors: Villet, Martin H
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451583 , vital:75061 , https://hdl.handle.net/10520/EJC32856
- Description: Despite their generally small sizes, southern African insects consistently attract public attention. Rarely is it positive attention, but when it is, it is often from notable champions. Let me explain.
- Full Text:
- Date Issued: 2010
- Authors: Villet, Martin H
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451583 , vital:75061 , https://hdl.handle.net/10520/EJC32856
- Description: Despite their generally small sizes, southern African insects consistently attract public attention. Rarely is it positive attention, but when it is, it is often from notable champions. Let me explain.
- Full Text:
- Date Issued: 2010
A life-history approach to the early ontogeny of the Mozambique tilapia Oreochromis mossambicus (Pisces, Cichlidae)
- Holden, Kathleen K, Bruton, Michael N
- Authors: Holden, Kathleen K , Bruton, Michael N
- Date: 1992
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447116 , vital:74585 , https://www.ajol.info/index.php/az/article/view/154193
- Description: The early ontogeny of Oreochromis mossambicus (Peters) was followed from the time of egg activation until the juvenile period. Development is direct and consists of an embryonic period of approximately 15 days. The embryonic period can be divided into a cleavage, an embryonic and a free-embryonic phase. A detailed developmental description is given and the relationship between the early ontogeny and the early life-history pattern is examined. The terminology used for the last step of the free-embryonic phase and a possible truncated larval period is discussed.
- Full Text:
- Date Issued: 1992
- Authors: Holden, Kathleen K , Bruton, Michael N
- Date: 1992
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447116 , vital:74585 , https://www.ajol.info/index.php/az/article/view/154193
- Description: The early ontogeny of Oreochromis mossambicus (Peters) was followed from the time of egg activation until the juvenile period. Development is direct and consists of an embryonic period of approximately 15 days. The embryonic period can be divided into a cleavage, an embryonic and a free-embryonic phase. A detailed developmental description is given and the relationship between the early ontogeny and the early life-history pattern is examined. The terminology used for the last step of the free-embryonic phase and a possible truncated larval period is discussed.
- Full Text:
- Date Issued: 1992
A lightwave 3d plug-in for modeling long hair on virtual humans
- Patrick, Deborah, Bangay, Shaun D
- Authors: Patrick, Deborah , Bangay, Shaun D
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432953 , vital:72916 , https://doi.org/10.1145/602330.602360
- Description: Multimedia applications today make use of virtual humans. Generating realistic virtual humans is a challenging problem owing to a number of factors, one being the simulation of realistic hair. The difficulty in simulating hair is due to the physical properties of hair. The average human head holds thousands of hairs, with the width of each hair often smaller than the size of a pixel. There are also complex lighting effects that occur within hair. This paper presents a LightWave 3D plug-in for modeling thousands of individual hairs on virtual humans. The plug-in allows the user to specify the length, thickness and distribution of the hair, as well as the number of segments a hair is made up of. The plug-in is able to add hairs to a head model, which the user then modifies to define a hairstyle. The hairs are then multiplied by the plug-in to produce many hairs. By providing a plug-in that does most of the work and produces realistic results, the user is able to produce a hairstyle without modeling each individual strand of hair. This greatly reduces the time spent on hair modeling, and makes the possibility of adding realistic long hair to virtual humans reasonable.
- Full Text:
- Date Issued: 2003
- Authors: Patrick, Deborah , Bangay, Shaun D
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432953 , vital:72916 , https://doi.org/10.1145/602330.602360
- Description: Multimedia applications today make use of virtual humans. Generating realistic virtual humans is a challenging problem owing to a number of factors, one being the simulation of realistic hair. The difficulty in simulating hair is due to the physical properties of hair. The average human head holds thousands of hairs, with the width of each hair often smaller than the size of a pixel. There are also complex lighting effects that occur within hair. This paper presents a LightWave 3D plug-in for modeling thousands of individual hairs on virtual humans. The plug-in allows the user to specify the length, thickness and distribution of the hair, as well as the number of segments a hair is made up of. The plug-in is able to add hairs to a head model, which the user then modifies to define a hairstyle. The hairs are then multiplied by the plug-in to produce many hairs. By providing a plug-in that does most of the work and produces realistic results, the user is able to produce a hairstyle without modeling each individual strand of hair. This greatly reduces the time spent on hair modeling, and makes the possibility of adding realistic long hair to virtual humans reasonable.
- Full Text:
- Date Issued: 2003
A lover’s shame
- Authors: Jones, Ward E
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275692 , vital:55071 , xlink:href="https://doi.org/10.1007/s10677-012-9356-5"
- Description: Shame is one of the more painful consequences of loving someone; my beloved’s doing something immoral can cause me to be ashamed of her. The guiding thought behind this paper is that explaining this phenomenon can tell us something about what it means to love. The phenomenon of beloved-induced shame has been largely neglected by philosophers working on shame, most of whom conceive of shame as being a reflexive attitude. Bennett Helm has recently suggested that in order to account for beloved-induced shame, we should deny the reflexivity of shame. After arguing that Helm’s account is inadequate, I proceed to develop an account of beloved-induced shame that rightly preserves its reflexivity. A familiar feature of love is that it involves an evaluative dependence; when I love someone, my well-being depends upon her life’s going well. I argue that loving someone also involves a persistent tendency to believe that her life is going well, in the sense that she is a good person, that she is not prone to wickedness. Lovers are inclined, more strongly than they otherwise would be, to give their beloveds the moral benefit of the doubt. These two features of loving—an evaluative dependence and a persistent tendency to believe in the beloved’s moral goodness—provide the conditions for a lover to experience shame when he discovers that his beloved has morally transgressed.
- Full Text:
- Date Issued: 2012
- Authors: Jones, Ward E
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275692 , vital:55071 , xlink:href="https://doi.org/10.1007/s10677-012-9356-5"
- Description: Shame is one of the more painful consequences of loving someone; my beloved’s doing something immoral can cause me to be ashamed of her. The guiding thought behind this paper is that explaining this phenomenon can tell us something about what it means to love. The phenomenon of beloved-induced shame has been largely neglected by philosophers working on shame, most of whom conceive of shame as being a reflexive attitude. Bennett Helm has recently suggested that in order to account for beloved-induced shame, we should deny the reflexivity of shame. After arguing that Helm’s account is inadequate, I proceed to develop an account of beloved-induced shame that rightly preserves its reflexivity. A familiar feature of love is that it involves an evaluative dependence; when I love someone, my well-being depends upon her life’s going well. I argue that loving someone also involves a persistent tendency to believe that her life is going well, in the sense that she is a good person, that she is not prone to wickedness. Lovers are inclined, more strongly than they otherwise would be, to give their beloveds the moral benefit of the doubt. These two features of loving—an evaluative dependence and a persistent tendency to believe in the beloved’s moral goodness—provide the conditions for a lover to experience shame when he discovers that his beloved has morally transgressed.
- Full Text:
- Date Issued: 2012
A Magical 'Dream': The Port Elizabeth Shakespearean Festival 2005
- Authors: Wright, Laurence
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455563 , vital:75439 , https://hdl.handle.net/10520/EJC48058
- Description: Mannville has always had a special relationship with this particular play, which inaugurated the theatre in St George's Park with Lesley French's 1972 production, and has been performed there on a number of occasions since. It is the archetypal Shakespearean show for outdoor theatre, and the PE Shakespearean Festival productions in a sense transport the delightful balmy (and sometimes barmy!) traditions established at the summertime open-air theatre in Regents Park, London, where Lesley French enjoyed so many triumphs--not least with this play--to Eastern Cape soil. Outdoor theatre has its risks, logistical and climatic, but when it comes off, as this show did, the result is vividly memorable.
- Full Text:
- Date Issued: 2005
- Authors: Wright, Laurence
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455563 , vital:75439 , https://hdl.handle.net/10520/EJC48058
- Description: Mannville has always had a special relationship with this particular play, which inaugurated the theatre in St George's Park with Lesley French's 1972 production, and has been performed there on a number of occasions since. It is the archetypal Shakespearean show for outdoor theatre, and the PE Shakespearean Festival productions in a sense transport the delightful balmy (and sometimes barmy!) traditions established at the summertime open-air theatre in Regents Park, London, where Lesley French enjoyed so many triumphs--not least with this play--to Eastern Cape soil. Outdoor theatre has its risks, logistical and climatic, but when it comes off, as this show did, the result is vividly memorable.
- Full Text:
- Date Issued: 2005
A method for automatically creating 3d animated scenes from annotated fiction text
- Glass, Kevin R, Bangay, Shaun D
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432699 , vital:72893 , https://www.iadisportal.org/ijcsis/papers/2009110208.pdf
- Description: This paper describes a strategy for automatically converting fiction text into 3D animations. It assumes the existence of fiction text annotated with avatar, object, setting, transition and relation annotations, and presents a transformation process that converts annotated text into quantified constraint systems, the solutions to which are used in the population of 3D environments. Constraint solutions are valid over temporal intervals, ensuring that consistent dynamic behaviour is produced. A substantial level of automation is achieved, while providing opportunities for creative manual intervention in animation process. The process is demonstrated using annotated examples drawn from popular fiction text that are converted into animation sequences, confirming that the desired results can be achieved with only high-level human direction.
- Full Text:
- Date Issued: 2009
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432699 , vital:72893 , https://www.iadisportal.org/ijcsis/papers/2009110208.pdf
- Description: This paper describes a strategy for automatically converting fiction text into 3D animations. It assumes the existence of fiction text annotated with avatar, object, setting, transition and relation annotations, and presents a transformation process that converts annotated text into quantified constraint systems, the solutions to which are used in the population of 3D environments. Constraint solutions are valid over temporal intervals, ensuring that consistent dynamic behaviour is produced. A substantial level of automation is achieved, while providing opportunities for creative manual intervention in animation process. The process is demonstrated using annotated examples drawn from popular fiction text that are converted into animation sequences, confirming that the desired results can be achieved with only high-level human direction.
- Full Text:
- Date Issued: 2009
A multiscale ONIOM study of the buckminsterfullerene (C60) Diels–Alder reaction: from model design to reaction path analysis
- Isamura, Bienfait K, Lobb, Kevin A
- Authors: Isamura, Bienfait K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452517 , vital:75140 , xlink:href=" https://link.springer.com/article/10.1007/s00894-022-05319-0"
- Description: The hybrid ONIOM (Our own N-layered Integrated molecular Orbital and molecular Mechanics) formalism is employed to investigate the Diels–Alder reaction of the buckminsterfullerene C60. Our computa-tions suggest that the ONIOM2(M06-2X/6-31G(d): SVWN/STO3G) mod-el, enclosing both the diene and the pyracyclene fragment of C60 in the higher-layer, provides a reasonable trade-of between accuracy and computational cost as it comes to predicting reaction energetics. Moreover, the frontier molecular orbital (FMO) theory and activation strain model (ASM) are jointly relied on to rationalize the efect of –OH and –CN substituents on the activation barrier of this reaction. Finally, reaction paths are scrutinized to get insight into the various forces un-derpinning the process of cycloadduct formation.
- Full Text:
- Date Issued: 2022
- Authors: Isamura, Bienfait K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452517 , vital:75140 , xlink:href=" https://link.springer.com/article/10.1007/s00894-022-05319-0"
- Description: The hybrid ONIOM (Our own N-layered Integrated molecular Orbital and molecular Mechanics) formalism is employed to investigate the Diels–Alder reaction of the buckminsterfullerene C60. Our computa-tions suggest that the ONIOM2(M06-2X/6-31G(d): SVWN/STO3G) mod-el, enclosing both the diene and the pyracyclene fragment of C60 in the higher-layer, provides a reasonable trade-of between accuracy and computational cost as it comes to predicting reaction energetics. Moreover, the frontier molecular orbital (FMO) theory and activation strain model (ASM) are jointly relied on to rationalize the efect of –OH and –CN substituents on the activation barrier of this reaction. Finally, reaction paths are scrutinized to get insight into the various forces un-derpinning the process of cycloadduct formation.
- Full Text:
- Date Issued: 2022
A naive salience-based method for speaker identification in fiction books
- Glass, Kevin R, Bangay, Shaun D
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432627 , vital:72888 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: This paper presents a salience-based technique for the annotation of directly quoted speech from fiction text. In particular, this paper determines to what extent a naïve (without the use of complex machine learning or knowledge-based techniques) scoring technique can be used for the identification of the speaker of speech quotes. The presented technique makes use of a scoring technique, similar to that commonly found in knowledge-poor anaphora resolution research, as well as a set of hand-coded rules for the final identification of the speaker of each quote in the text. Speaker identification is shown to be achieved using three tasks: the identification of a speech-verb associated with a quote with a recall of 94.41%; the identification of the actor associated with a quote with a recall of 88.22%; and the selection of a speaker with an accuracy of 79.40%.
- Full Text:
- Date Issued: 2007
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432627 , vital:72888 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: This paper presents a salience-based technique for the annotation of directly quoted speech from fiction text. In particular, this paper determines to what extent a naïve (without the use of complex machine learning or knowledge-based techniques) scoring technique can be used for the identification of the speaker of speech quotes. The presented technique makes use of a scoring technique, similar to that commonly found in knowledge-poor anaphora resolution research, as well as a set of hand-coded rules for the final identification of the speaker of each quote in the text. Speaker identification is shown to be achieved using three tasks: the identification of a speech-verb associated with a quote with a recall of 94.41%; the identification of the actor associated with a quote with a recall of 88.22%; and the selection of a speaker with an accuracy of 79.40%.
- Full Text:
- Date Issued: 2007