An investigation into factors influencing immersion in interactive virtual reality environments
- Bangay, Shaun D, Preston, Louise
- Authors: Bangay, Shaun D , Preston, Louise
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432864 , vital:72908 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: Two interactive virtual reality environments were used to identify factors that may affect, or be affected by, the degree of immersion in a virtual world. In particular, the level of stress in a "swimming with dolphins" simulation is measured, as is the degree of simulator sickness resulting form a virtual roller coaster. Analysis of the results indicates that a relationship between the degree of immersion and the following factors: excitement, comfort, quality and age. The following factors are found to depend on the degree of immersion: simulator sickness, control, excitement and desire to repeat the experience.
- Full Text:
- Date Issued: 1998
- Authors: Bangay, Shaun D , Preston, Louise
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432864 , vital:72908 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: Two interactive virtual reality environments were used to identify factors that may affect, or be affected by, the degree of immersion in a virtual world. In particular, the level of stress in a "swimming with dolphins" simulation is measured, as is the degree of simulator sickness resulting form a virtual roller coaster. Analysis of the results indicates that a relationship between the degree of immersion and the following factors: excitement, comfort, quality and age. The following factors are found to depend on the degree of immersion: simulator sickness, control, excitement and desire to repeat the experience.
- Full Text:
- Date Issued: 1998
An Investigation into the feasibility of Human Facial Modeling
- Panagou, Sotcri, Bangay, Shaun D
- Authors: Panagou, Sotcri , Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432711 , vital:72894 , https://citeseerx.ist.psu.edu/document?repid=rep1ype=pdfoi=c305c27d16322208e0e6815ca261d61019a4cbd0
- Description: In this paper, virtual videoconferencing is investigated. The goal of the project is to develop a cheap, realistic yet real-time 3D face-modeling tool using a number of camera feeds. Bandwidth utilisation can then be minimised by transferring only the actual model (and subsequently, changes to the model) of the actor's face. Using a virtual reality system, reconstruction of a human face is performed and transmitted, thereby reducing bandwidth requirements. The modeling process is discussed, with results.
- Full Text:
- Date Issued: 1998
- Authors: Panagou, Sotcri , Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432711 , vital:72894 , https://citeseerx.ist.psu.edu/document?repid=rep1ype=pdfoi=c305c27d16322208e0e6815ca261d61019a4cbd0
- Description: In this paper, virtual videoconferencing is investigated. The goal of the project is to develop a cheap, realistic yet real-time 3D face-modeling tool using a number of camera feeds. Bandwidth utilisation can then be minimised by transferring only the actual model (and subsequently, changes to the model) of the actor's face. Using a virtual reality system, reconstruction of a human face is performed and transmitted, thereby reducing bandwidth requirements. The modeling process is discussed, with results.
- Full Text:
- Date Issued: 1998
Democratic South Africa and the Asian paragon: issues of foreign policy orientation
- Authors: Bischoff, Paul, 1954-
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161420 , vital:40625 , https://www.jstor.org/stable/40180338
- Description: Not unlike Spain after Franco in the 1970s, post-Apartheid South Africa in the 1990s, is a state whose democracy is built on a broad based effort to manage a transformation towards constitutionalism and the open rule of law. In what is still an ongoing process towards the transformation of public life, a democratising South Africa remains a prime example of one of the most hopeful democratic orders in the Southern hemisphere. How this state, engaged in transformation at home, projects itself in its relations with other, largely less democratic states abroad, represents a test for the evolution of a foreign policy which pays heed to both economic need as well as its newly won democratic credentials. In the country's relations with Asia, the attempt to strike a balance between the two concerns, is something which points, more than anything else, to the ongoing, evolving nature of South African foreign policy.
- Full Text:
- Date Issued: 1998
- Authors: Bischoff, Paul, 1954-
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161420 , vital:40625 , https://www.jstor.org/stable/40180338
- Description: Not unlike Spain after Franco in the 1970s, post-Apartheid South Africa in the 1990s, is a state whose democracy is built on a broad based effort to manage a transformation towards constitutionalism and the open rule of law. In what is still an ongoing process towards the transformation of public life, a democratising South Africa remains a prime example of one of the most hopeful democratic orders in the Southern hemisphere. How this state, engaged in transformation at home, projects itself in its relations with other, largely less democratic states abroad, represents a test for the evolution of a foreign policy which pays heed to both economic need as well as its newly won democratic credentials. In the country's relations with Asia, the attempt to strike a balance between the two concerns, is something which points, more than anything else, to the ongoing, evolving nature of South African foreign policy.
- Full Text:
- Date Issued: 1998
From Sequencer to IP Packets-Routing MIDI Messages Over Longer Distances
- Authors: Foss, Richard
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427418 , vital:72437 , https://www.aes.org/e-lib/browse.cfm?elib=8476
- Description: This paper describes the operation, and design of a MIDI-to-IP-to-MIDI router which overcomes the channel and distance limitations inherent in the MIDI protocol. It allows Windows-based programs and MIDI transmitters to route MIDI messages over long distances to MIDI receiving devices. Each networked PC in the system has one or more MIDI input/output ports. MIDI transmitters and receivers are connected to the input and output ports, respectively, and are given symbolic names. The system allows connections to be made between the transmitters and receivers.
- Full Text:
- Date Issued: 1998
- Authors: Foss, Richard
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427418 , vital:72437 , https://www.aes.org/e-lib/browse.cfm?elib=8476
- Description: This paper describes the operation, and design of a MIDI-to-IP-to-MIDI router which overcomes the channel and distance limitations inherent in the MIDI protocol. It allows Windows-based programs and MIDI transmitters to route MIDI messages over long distances to MIDI receiving devices. Each networked PC in the system has one or more MIDI input/output ports. MIDI transmitters and receivers are connected to the input and output ports, respectively, and are given symbolic names. The system allows connections to be made between the transmitters and receivers.
- Full Text:
- Date Issued: 1998
Geochemical variations in a long Karoo dyke, Eastern Cape
- Marsh, Julian S, Mndaweni, M J
- Authors: Marsh, Julian S , Mndaweni, M J
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149715 , vital:38877 , https://hdl.handle.net/10520/EJC-1abee09c1f
- Description: A prominent vertical dolerite dyke, up to 30 m wide and which can be traced for over 100 km, is compositionally homogeneous along much of its length and shows no evidence of flow differentiation. Associated parallel dykes are compositionally distinct and are unrelated by closed-system processes. The main dyke has geochemical characteristics of the Maloti or Senqu Units in the upper part of the main Lesotho basalt sequence, whereas the parallel dykes are geochemically similar to the lower Mafika Lisiu Unit. On the basis of size and composition the main dyke may well represent a fissure which once fed effusions of Karoo basalt.
- Full Text:
- Date Issued: 1998
- Authors: Marsh, Julian S , Mndaweni, M J
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149715 , vital:38877 , https://hdl.handle.net/10520/EJC-1abee09c1f
- Description: A prominent vertical dolerite dyke, up to 30 m wide and which can be traced for over 100 km, is compositionally homogeneous along much of its length and shows no evidence of flow differentiation. Associated parallel dykes are compositionally distinct and are unrelated by closed-system processes. The main dyke has geochemical characteristics of the Maloti or Senqu Units in the upper part of the main Lesotho basalt sequence, whereas the parallel dykes are geochemically similar to the lower Mafika Lisiu Unit. On the basis of size and composition the main dyke may well represent a fissure which once fed effusions of Karoo basalt.
- Full Text:
- Date Issued: 1998
Good faith and procedural unfairness in contract: Eerste Nationale Bank van Suidelike Afrika Bpk v Saayman 1997 (4) SA 302 (A)
- Authors: Glover, Graham B
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/155975 , vital:39937 , https://heinonline.org/HOL/Page?collection=journalsamp;handle=hein.journals/tyromhldre61amp;id=358amp;men_tab=srchresults
- Description: "It is unlikely that Bank of Lisbon will remain the last word on the matter of good faith and contract law" (Zimmermann "Good faith and equity" in Zimmermann and Visser (eds) Southern cross: Civil law and common law in South Africa (1996) 256). These words have proved to be prophetic in the light of the recent decision handed down by the Supreme Court of Appeal in Eerste Nasionale Bank van Suidelike Afrika Bpk v Saayman.
- Full Text: false
- Date Issued: 1998
- Authors: Glover, Graham B
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/155975 , vital:39937 , https://heinonline.org/HOL/Page?collection=journalsamp;handle=hein.journals/tyromhldre61amp;id=358amp;men_tab=srchresults
- Description: "It is unlikely that Bank of Lisbon will remain the last word on the matter of good faith and contract law" (Zimmermann "Good faith and equity" in Zimmermann and Visser (eds) Southern cross: Civil law and common law in South Africa (1996) 256). These words have proved to be prophetic in the light of the recent decision handed down by the Supreme Court of Appeal in Eerste Nasionale Bank van Suidelike Afrika Bpk v Saayman.
- Full Text: false
- Date Issued: 1998
In vitro release of amoxycillin from lipophilic suppositories
- Webster, Jessica A, Dowse, Roslind, Walker, Roderick B
- Authors: Webster, Jessica A , Dowse, Roslind , Walker, Roderick B
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184377 , vital:44213 , xlink:href="https://doi.org/10.3109/03639049809085636"
- Description: The in vitro release characteristics of amoxycillin from different lipophilic suppository bases were investigated using the USP rotating basket method. Suppositories containing 250 mg amoxycillin were prepared in theobroma oil and in the semisynthetic bases Witepsol W35, Suppocire A32, Novata BD, and Novata 299. Both freshly prepared and 1-month-old suppositories were tested. Analysis of amoxycillin was performed using a validated high-performance liquid chromatographic (HPLC) technique. Release profiles differed significantly between bases, with the greatest amount of amoxycillin being released from both newly made and 1-month-old Novata BD bases (87.57 ± 8.18 and 99.66 ± 6.63%, respectively), and the lowest amount released from the newly manufactured theobroma suppositories (8.82 ± 0.75%) and the 1-month-old Suppocire A32 suppositories (7.78 ± 0.27%).
- Full Text:
- Date Issued: 1998
- Authors: Webster, Jessica A , Dowse, Roslind , Walker, Roderick B
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184377 , vital:44213 , xlink:href="https://doi.org/10.3109/03639049809085636"
- Description: The in vitro release characteristics of amoxycillin from different lipophilic suppository bases were investigated using the USP rotating basket method. Suppositories containing 250 mg amoxycillin were prepared in theobroma oil and in the semisynthetic bases Witepsol W35, Suppocire A32, Novata BD, and Novata 299. Both freshly prepared and 1-month-old suppositories were tested. Analysis of amoxycillin was performed using a validated high-performance liquid chromatographic (HPLC) technique. Release profiles differed significantly between bases, with the greatest amount of amoxycillin being released from both newly made and 1-month-old Novata BD bases (87.57 ± 8.18 and 99.66 ± 6.63%, respectively), and the lowest amount released from the newly manufactured theobroma suppositories (8.82 ± 0.75%) and the 1-month-old Suppocire A32 suppositories (7.78 ± 0.27%).
- Full Text:
- Date Issued: 1998
Interaction of nitric oxide with cobalt (II) phthalocyanine
- Vilakazi, Sibulelo L, Nyokong, Tebello
- Authors: Vilakazi, Sibulelo L , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293579 , vital:57100 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00244-7"
- Description: The coordination of nitric oxide (NO) to cobalt(II) phthalocyanine (CoPc) in dimethyl sulphoxide (DMSO) has been studied. CoPc coordinates with NO in a 1:1 ratio, forming a CoPc(NO) species. The IR band observed at 1680 cm−1 is assigned to the coordinated NO. In the presence of excess NO, pseudo first order kinetics were followed. The observed rate constant, kf, was determined to be 15.0±0.3 dm−3 mol−1 s−1 and the equilibrium constant was K=5.4±0.4×104dm3 mol−1. Solution or adsorbed CoPc catalyses the reduction of NO. The products of reduction include NH3 and NH2OH.
- Full Text:
- Date Issued: 1998
- Authors: Vilakazi, Sibulelo L , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293579 , vital:57100 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00244-7"
- Description: The coordination of nitric oxide (NO) to cobalt(II) phthalocyanine (CoPc) in dimethyl sulphoxide (DMSO) has been studied. CoPc coordinates with NO in a 1:1 ratio, forming a CoPc(NO) species. The IR band observed at 1680 cm−1 is assigned to the coordinated NO. In the presence of excess NO, pseudo first order kinetics were followed. The observed rate constant, kf, was determined to be 15.0±0.3 dm−3 mol−1 s−1 and the equilibrium constant was K=5.4±0.4×104dm3 mol−1. Solution or adsorbed CoPc catalyses the reduction of NO. The products of reduction include NH3 and NH2OH.
- Full Text:
- Date Issued: 1998
Photoassisted reduction of thionyl chloride by neodymium, europium, thulium and lutetium diphthalocyanines
- Nensala, Ngudiankama, Nyokong, Tebello
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293590 , vital:57101 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00133-8"
- Description: Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (larger than 10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.
- Full Text:
- Date Issued: 1998
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293590 , vital:57101 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00133-8"
- Description: Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (larger than 10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.
- Full Text:
- Date Issued: 1998
Pictograms in pharmacy:
- Dowse, Roslind, Ehlers, Martina S
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157048 , vital:40082 , https://0-doi.org.wam.seals.ac.za/10.1111/j.2042-7174.1998.tb00924.x
- Description: This review examines the use of pictograms in health care. Well designed pictograms are simple, clear, graphic symbols able to convey their intended meaning to all patients, including those who are illiterate, elderly or visually impaired. Although some research on the effectiveness of pictograms has not supported the hypothesis that pictograms are beneficial for the acquisition and comprehension of information, most studies investigating health‐related applications of pictograms have shown them to be of benefit in the comprehension and recall of instructions on prescription and over‐the‐counter medicines. However, the success of pictograms as a communication aid in pharmacy depends first on a rigorous design process, followed by well‐designed, randomised, controlled trials using an appropriate method of evaluation. The final stage is to investigate the optimal way of using pictograms in practice and to assess their effect on behavioural outcomes, such as compliance.
- Full Text:
- Date Issued: 1998
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157048 , vital:40082 , https://0-doi.org.wam.seals.ac.za/10.1111/j.2042-7174.1998.tb00924.x
- Description: This review examines the use of pictograms in health care. Well designed pictograms are simple, clear, graphic symbols able to convey their intended meaning to all patients, including those who are illiterate, elderly or visually impaired. Although some research on the effectiveness of pictograms has not supported the hypothesis that pictograms are beneficial for the acquisition and comprehension of information, most studies investigating health‐related applications of pictograms have shown them to be of benefit in the comprehension and recall of instructions on prescription and over‐the‐counter medicines. However, the success of pictograms as a communication aid in pharmacy depends first on a rigorous design process, followed by well‐designed, randomised, controlled trials using an appropriate method of evaluation. The final stage is to investigate the optimal way of using pictograms in practice and to assess their effect on behavioural outcomes, such as compliance.
- Full Text:
- Date Issued: 1998
Port Elizabeth History: A Select Annotated Bibliography
- Authors: Baines, Gary F
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125742 , vital:35813 , https://doi.10.1080/02582479808671323
- Description: When I commenced my work on aspects of Port Elizabeth’s history in the late 1980s, there was no body of scholarly literature on which to draw. Since thena number of significant publications, both periodical articles and books, as well as theses have appeared, and something of a corpus of works on the city now exists. It seems appropriate to take stock of the current state of Port Elizabeth’s historiography by compiling a bibliography.
- Full Text:
- Date Issued: 1998
- Authors: Baines, Gary F
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125742 , vital:35813 , https://doi.10.1080/02582479808671323
- Description: When I commenced my work on aspects of Port Elizabeth’s history in the late 1980s, there was no body of scholarly literature on which to draw. Since thena number of significant publications, both periodical articles and books, as well as theses have appeared, and something of a corpus of works on the city now exists. It seems appropriate to take stock of the current state of Port Elizabeth’s historiography by compiling a bibliography.
- Full Text:
- Date Issued: 1998
Prince Edward Islands' offshore oceanographic study: report of research cruise April-May 1997
- Pakhomov, E A, Froneman, Pierre William, Ansorge, Isabelle J
- Authors: Pakhomov, E A , Froneman, Pierre William , Ansorge, Isabelle J
- Date: 1998
- Language: English
- Type: text , article
- Identifier: vital:6939 , http://hdl.handle.net/10520/AJA00382353_9017 , https://journals.co.za/content/sajsci/94/4/AJA00382353_9017 , http://hdl.handle.net/10962/d1011962
- Description: preprint , Focuses on the preliminary results of the second cruise of the Marion Island Oceanographic Study designed to provide oceanological observations off Prince Edward Islands from April 25 to May 28, 1997. Physical and chemical oceanographic results; Surface seawater temperature; Total chlorophyll-a distribution.
- Full Text:
- Date Issued: 1998
- Authors: Pakhomov, E A , Froneman, Pierre William , Ansorge, Isabelle J
- Date: 1998
- Language: English
- Type: text , article
- Identifier: vital:6939 , http://hdl.handle.net/10520/AJA00382353_9017 , https://journals.co.za/content/sajsci/94/4/AJA00382353_9017 , http://hdl.handle.net/10962/d1011962
- Description: preprint , Focuses on the preliminary results of the second cruise of the Marion Island Oceanographic Study designed to provide oceanological observations off Prince Edward Islands from April 25 to May 28, 1997. Physical and chemical oceanographic results; Surface seawater temperature; Total chlorophyll-a distribution.
- Full Text:
- Date Issued: 1998
Problems in rural transformation in South Africa specifically in the land reform arena:
- Antrobus, Geoffrey G, Fraser, Gavin C G, Tapson, D R
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G , Tapson, D R
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143035 , vital:38195 , https://www.infona.pl/resource/bwmeta1.element.agro-article-dc77672d-7269-4641-bf99-605eaa5fe369
- Description: Problems in rural transformation in South Africa specifically in the land reform arena
- Full Text:
- Date Issued: 1998
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G , Tapson, D R
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143035 , vital:38195 , https://www.infona.pl/resource/bwmeta1.element.agro-article-dc77672d-7269-4641-bf99-605eaa5fe369
- Description: Problems in rural transformation in South Africa specifically in the land reform arena
- Full Text:
- Date Issued: 1998
The interaction of melatonin and its precursors with aluminium, cadmium, copper, iron, lead, and zinc
- Limson, Janice L, Nyokong, Tebello, Daya, Santy
- Authors: Limson, Janice L , Nyokong, Tebello , Daya, Santy
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293323 , vital:57075 , xlink:href="https://doi.org/10.1111/j.1600-079X.1998.tb00361.x"
- Description: Melatonin, a pineal secretory product, and its precursors, tryptophan and serotonin, were examined for their metal binding affinities for both essential and toxic metals: aluminium, cadmium, copper, iron, lead, and zinc. An electrochemical technique, adsorptive stripping voltammetry, showed the varying abilities of melatonin and its precursors to bind the metals in situ. The results show that the following metal complexes were formed: aluminium with melatonin, tryptophan, and serotonin; cadmium with melatonin and tryptophan; copper with melatonin and serotonin; iron(III) with melatonin and serotonin; lead with melatonin, tryptophan, and serotonin; and zinc with melatonin and tryptophan. Iron(II) showed the formation of an in situ complex with tryptophan only. These studies suggest a further role for melatonin in the reduction of free radical generation and metal detoxification, and they may explain the accumulation of aluminium in Alzheimer's disease.
- Full Text:
- Date Issued: 1998
- Authors: Limson, Janice L , Nyokong, Tebello , Daya, Santy
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293323 , vital:57075 , xlink:href="https://doi.org/10.1111/j.1600-079X.1998.tb00361.x"
- Description: Melatonin, a pineal secretory product, and its precursors, tryptophan and serotonin, were examined for their metal binding affinities for both essential and toxic metals: aluminium, cadmium, copper, iron, lead, and zinc. An electrochemical technique, adsorptive stripping voltammetry, showed the varying abilities of melatonin and its precursors to bind the metals in situ. The results show that the following metal complexes were formed: aluminium with melatonin, tryptophan, and serotonin; cadmium with melatonin and tryptophan; copper with melatonin and serotonin; iron(III) with melatonin and serotonin; lead with melatonin, tryptophan, and serotonin; and zinc with melatonin and tryptophan. Iron(II) showed the formation of an in situ complex with tryptophan only. These studies suggest a further role for melatonin in the reduction of free radical generation and metal detoxification, and they may explain the accumulation of aluminium in Alzheimer's disease.
- Full Text:
- Date Issued: 1998
The Marinkas Quellen Carbonatite Complex, southern Namibia: carbonatite magmatism with an uncontaminated depleted mantle signature in a continental setting
- Smithies, Robert H, Marsh, Julian S
- Authors: Smithies, Robert H , Marsh, Julian S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149736 , vital:38879 , https://doi.org/10.1016/S0009-2541(98)00029-1
- Description: The Marinkas Quellen Carbonatite Complex, in southern Namibia, forms part of the ca. 490–550 Ma Kuboos-Bremen Igneous Province, a zone of alkaline igneous rocks that intrude the Mesoproterzoic to Paleoproterozoic Namaqualand Metamorphic Province and Neoproterozoic platform sediments. The carbonatite complex includes Ca-rich, Mg-rich and Fe-rich carbonatites as well as late ferrocarbonatite dykes that show extreme enrichments in Mn, REE and Th. Compared to most carbonatites, those at Marinkas Quellen are generally depleted in most trace elements, particularly Ba and the LREE.
- Full Text: false
- Date Issued: 1998
- Authors: Smithies, Robert H , Marsh, Julian S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149736 , vital:38879 , https://doi.org/10.1016/S0009-2541(98)00029-1
- Description: The Marinkas Quellen Carbonatite Complex, in southern Namibia, forms part of the ca. 490–550 Ma Kuboos-Bremen Igneous Province, a zone of alkaline igneous rocks that intrude the Mesoproterzoic to Paleoproterozoic Namaqualand Metamorphic Province and Neoproterozoic platform sediments. The carbonatite complex includes Ca-rich, Mg-rich and Fe-rich carbonatites as well as late ferrocarbonatite dykes that show extreme enrichments in Mn, REE and Th. Compared to most carbonatites, those at Marinkas Quellen are generally depleted in most trace elements, particularly Ba and the LREE.
- Full Text: false
- Date Issued: 1998
Understanding and responding to student learning difficulties within the higher education context
- Amos, Trevor L, Fischer, Sarah
- Authors: Amos, Trevor L , Fischer, Sarah
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270972 , vital:54497 , xlink:href="https://hdl.handle.net/10520/AJA10113487_570"
- Description: Higher education in South Africa is challenged to promote the academic success of students through quality teaching and learning. This article provides a sound theoretical understanding of student learning difficulties as difficulties of accessing and mastering the cognitive processes entailed in the groundrules of the specific academic disciplines within higher education Based on this theoretical groundwork. the article argues for the integration of academic development into the mainstream teaching and learning activities of specific disciplines where the tutorial system is used to develop the specific academic literacy required for success within the discipline.
- Full Text:
- Date Issued: 1998
- Authors: Amos, Trevor L , Fischer, Sarah
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270972 , vital:54497 , xlink:href="https://hdl.handle.net/10520/AJA10113487_570"
- Description: Higher education in South Africa is challenged to promote the academic success of students through quality teaching and learning. This article provides a sound theoretical understanding of student learning difficulties as difficulties of accessing and mastering the cognitive processes entailed in the groundrules of the specific academic disciplines within higher education Based on this theoretical groundwork. the article argues for the integration of academic development into the mainstream teaching and learning activities of specific disciplines where the tutorial system is used to develop the specific academic literacy required for success within the discipline.
- Full Text:
- Date Issued: 1998
Virtual reality interaction techniques
- Rorke, Michael, Bangay, Shaun D, Wentworth, Peter E
- Authors: Rorke, Michael , Bangay, Shaun D , Wentworth, Peter E
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432756 , vital:72897 , https://citeseerx.ist.psu.edu/document?repid=rep1type=pdfdoi=d0b11136ef6d2701e15cdda896bc5bfd0786752e
- Description: This paper addresses the problems associated with interaction in immersive virtual reality and makes recommendations as to how best to deal with these problems, thereby producing a usable virtual reality interactive environment. Immersive virtual reality means that the users are immersed or contained inside the environment in which they are working. For example, they are able to turn their heads and look around, as well as use their bodies to control the system. The work in progress involves a study of various virtual reality input devices, some designed and implemented as part of the project. Additionally, the paper describes a simple framework for separation of the interaction and application parts of a virtual reality system in order to facilitate an object ori-ented approach to the implementation of the recommendations, and to the building of future virtual reality applications which incorporate these ideas.
- Full Text:
- Date Issued: 1998
- Authors: Rorke, Michael , Bangay, Shaun D , Wentworth, Peter E
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432756 , vital:72897 , https://citeseerx.ist.psu.edu/document?repid=rep1type=pdfdoi=d0b11136ef6d2701e15cdda896bc5bfd0786752e
- Description: This paper addresses the problems associated with interaction in immersive virtual reality and makes recommendations as to how best to deal with these problems, thereby producing a usable virtual reality interactive environment. Immersive virtual reality means that the users are immersed or contained inside the environment in which they are working. For example, they are able to turn their heads and look around, as well as use their bodies to control the system. The work in progress involves a study of various virtual reality input devices, some designed and implemented as part of the project. Additionally, the paper describes a simple framework for separation of the interaction and application parts of a virtual reality system in order to facilitate an object ori-ented approach to the implementation of the recommendations, and to the building of future virtual reality applications which incorporate these ideas.
- Full Text:
- Date Issued: 1998
Visiview: a system for the visualization of multidimensional data
- Authors: Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433466 , vital:72972 , https://doi.org/10.1117/12.309530
- Description: Results generated by simulation of computer systems are often presented as a multi-dimensional data set, where the number of dimensions may be greater than 4 if sufficient system parameters are modelled. This paper describes a visualization system intended to assist in understanding the relationship between, and effect upon system behavior of, the different values of the system parameters. The system is applied to data that cannot be represented using a mesh or isosurface representation, and in general can only be represented as a cloud of points. The use of stereoscopic rendering and rapid interaction with the data are compared with regard to their value in providing insight into the nature of the data. A number of techniques are implemented for displaying projections of the data set with up to 7 dimensions, and for allowing intuitive manipulation of the remaining dimensions. In this way the effect of changes in one variable in the presence of a number of others can be explored. The use of these techniques, when applied to data from computer system simulation, results in an intuitive understanding of the effects of the system parameters on system behavior.
- Full Text:
- Date Issued: 1998
- Authors: Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433466 , vital:72972 , https://doi.org/10.1117/12.309530
- Description: Results generated by simulation of computer systems are often presented as a multi-dimensional data set, where the number of dimensions may be greater than 4 if sufficient system parameters are modelled. This paper describes a visualization system intended to assist in understanding the relationship between, and effect upon system behavior of, the different values of the system parameters. The system is applied to data that cannot be represented using a mesh or isosurface representation, and in general can only be represented as a cloud of points. The use of stereoscopic rendering and rapid interaction with the data are compared with regard to their value in providing insight into the nature of the data. A number of techniques are implemented for displaying projections of the data set with up to 7 dimensions, and for allowing intuitive manipulation of the remaining dimensions. In this way the effect of changes in one variable in the presence of a number of others can be explored. The use of these techniques, when applied to data from computer system simulation, results in an intuitive understanding of the effects of the system parameters on system behavior.
- Full Text:
- Date Issued: 1998
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