Electrocatalytic detection of amitrole on the multi-walled carbon nanotube–iron (II) tetra-aminophthalocyanine platform
- Siswana, Msimelelo P, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Siswana, Msimelelo P , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265924 , vital:53901 , xlink:href="https://doi.org/10.3390/s8085096"
- Description: It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of amitrole at this electrode occurred at less positive potential (~0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to amitrole in the presence of other potential interfering pesticides in aqueous solutions.
- Full Text:
- Date Issued: 2008
- Authors: Siswana, Msimelelo P , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265924 , vital:53901 , xlink:href="https://doi.org/10.3390/s8085096"
- Description: It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of amitrole at this electrode occurred at less positive potential (~0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to amitrole in the presence of other potential interfering pesticides in aqueous solutions.
- Full Text:
- Date Issued: 2008
Electrochemical and electrocatalytic properties of α-substituted manganese and titanium phthalocyanines
- Nombona, Nolwazi, Tau, Prudence, Sehlotho, Nthapo, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Tau, Prudence , Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268587 , vital:54212 , xlink:href="https://doi.org/10.1016/j.electacta.2007.11.046"
- Description: This work reports on the synthesis of manganese and titanium phthalocyanine complexes that are tetra-substituted at four non-peripheral positions with amino ligands. The complexes are investigated for the first time for their electrochemical properties using cyclic voltammetry, rotating disc electrode voltammetry and spectroelectrochemistry. Electropolymerisation on a glassy carbon electrode was performed with ease and the modified electrodes were investigated for electrocatalysis of nitrite oxidation. Nitrite oxidation to nitrate is confirmed from the transfer of a total of two electrons.
- Full Text:
- Date Issued: 2008
- Authors: Nombona, Nolwazi , Tau, Prudence , Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268587 , vital:54212 , xlink:href="https://doi.org/10.1016/j.electacta.2007.11.046"
- Description: This work reports on the synthesis of manganese and titanium phthalocyanine complexes that are tetra-substituted at four non-peripheral positions with amino ligands. The complexes are investigated for the first time for their electrochemical properties using cyclic voltammetry, rotating disc electrode voltammetry and spectroelectrochemistry. Electropolymerisation on a glassy carbon electrode was performed with ease and the modified electrodes were investigated for electrocatalysis of nitrite oxidation. Nitrite oxidation to nitrate is confirmed from the transfer of a total of two electrons.
- Full Text:
- Date Issued: 2008
Electrochemical Characterization of Self-Assembled Monolayer of a Novel Manganese Tetrabenzylthio-Substituted Phthalocyanine and Its Use in Nitrite Oxidation
- Matemadombo, Fungisai, Griveau, Sophie, Bedioui, Fethi, Nyokong, Tebello
- Authors: Matemadombo, Fungisai , Griveau, Sophie , Bedioui, Fethi , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265950 , vital:53903 , xlink:href="https://doi.org/10.1002/elan.200804269"
- Description: Manganese phthalocyanine MnPc(SPh)4 has been synthesized and used to form self assembled monolayers on gold electrodes. The well packed SAM monolayer was characterized by analyzing the blocking of a number of Faradic processes by cyclic voltammetry, evaluating the electrical characteristics of the modified electrode by electrochemical impedance and imaging the modified surface by electrochemical scanning microscopy. Finally, MnPc(SPh)4-SAM modified electrode displayed an electrocatalytic behavior toward the oxidation of nitrite.
- Full Text:
- Date Issued: 2008
- Authors: Matemadombo, Fungisai , Griveau, Sophie , Bedioui, Fethi , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265950 , vital:53903 , xlink:href="https://doi.org/10.1002/elan.200804269"
- Description: Manganese phthalocyanine MnPc(SPh)4 has been synthesized and used to form self assembled monolayers on gold electrodes. The well packed SAM monolayer was characterized by analyzing the blocking of a number of Faradic processes by cyclic voltammetry, evaluating the electrical characteristics of the modified electrode by electrochemical impedance and imaging the modified surface by electrochemical scanning microscopy. Finally, MnPc(SPh)4-SAM modified electrode displayed an electrocatalytic behavior toward the oxidation of nitrite.
- Full Text:
- Date Issued: 2008
Electrooxidation of hydrazine catalyzed by noncovalently functionalized single-walled carbon nanotubes with CoPc
- Geraldo, Daniela A, Togo, Chamunorwa A, Limson, Janice L, Nyokong, Tebello
- Authors: Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice L , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265963 , vital:53904 , xlink:href="https://doi.org/10.1016/j.electacta.2008.05.083"
- Description: We report on the electrooxidation of hydrazine catalyzed by single-walled carbon nanotube (SWCNT) functionalized with cobalt phthalocyanine (CoPc) which shows that the presence of the single-walled carbon nanotubes enhances the catalytic activity of the CoPc itself without any change in the reaction mechanism. A synergistic effect, in terms of reactivity when the new nanocomposite material was adsorbed on the GC electrode, was observed. The obtained hybrid electrodes were tested under hydrodynamic conditions, showing two different oxidation processes, which suggest the presence of two different types of active sites on the electrode surface catalyzing the reaction. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the GC/SWCNT + CoPc showed much lower electron-resistance (Ret) confirming the synergistic effect of the composite mentioned above. Atomic force microscopy (AFM) images showed the clear differences in surface roughness for each film, confirming the different compositions of the hybrid electrodes used in this study.
- Full Text:
- Date Issued: 2008
- Authors: Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice L , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265963 , vital:53904 , xlink:href="https://doi.org/10.1016/j.electacta.2008.05.083"
- Description: We report on the electrooxidation of hydrazine catalyzed by single-walled carbon nanotube (SWCNT) functionalized with cobalt phthalocyanine (CoPc) which shows that the presence of the single-walled carbon nanotubes enhances the catalytic activity of the CoPc itself without any change in the reaction mechanism. A synergistic effect, in terms of reactivity when the new nanocomposite material was adsorbed on the GC electrode, was observed. The obtained hybrid electrodes were tested under hydrodynamic conditions, showing two different oxidation processes, which suggest the presence of two different types of active sites on the electrode surface catalyzing the reaction. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the GC/SWCNT + CoPc showed much lower electron-resistance (Ret) confirming the synergistic effect of the composite mentioned above. Atomic force microscopy (AFM) images showed the clear differences in surface roughness for each film, confirming the different compositions of the hybrid electrodes used in this study.
- Full Text:
- Date Issued: 2008
Employee performance, leadership style and emotional intelligence
- Hayward, Brett A, Amos, Trevor L, Baxter, Jeremy
- Authors: Hayward, Brett A , Amos, Trevor L , Baxter, Jeremy
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270077 , vital:54393 , xlink:href="https://hdl.handle.net/10520/EJC17031"
- Description: Purpose: The purpose of this research is to explore the relationship between employee performance, leadership style and emotional intelligence in the context of a South African parastatal. Problem Investigated: There is a lack of literature and empirical research on the type of leadership required to achieve high levels of employee performance within South African parastatals. Methodology: The Multifactor Leadership Questionnaire (MLQ) was used to determine leadership style, while the Emotional Competency Profiler (ECP) was used to determine the emotional intelligence of the sample of leaders. Employee performance data was provided by the parastatal, based on their performance management system. Data was analysed using correlation analysis, multiple regression analysis, the standard regression ANOVA/F-test, t-tests and Cronbach alpha reliability coefficient. Findings: The findings of the research show that the ECP is a reliable measure of emotional intelligence and that while the MLQ is a reliable measure of transformational leadership, it is not a reliable measure of transactional leadership. The results of the correlation analysis show a positive significant relationship between emotional intelligence and transformational leadership and a negative significant relationship between employee performance and emotional intelligence. The results of regressing employee performance on emotional intelligence and transformational leadership show that emotional intelligence and transformational leadership have no significant effect on employee performance. The results of the regression models of the research could be biased by the lack of variance in employee performance data. Value of the Research: The value of the research lies in it confirming the MLQ as a reliable measure of transformational leadership and the ECP as a reliable measure of emotional intelligence. The finding of a positive significant relationship between emotional intelligence and transformational leadership is a valuable contribution to the literature. Conclusion: Although a positive significant relationship between emotional intelligence and transformational leadership was found, there is a need for further research to determine the type of leadership best suited to achieve high levels of employee performance within the parastatal.
- Full Text:
- Date Issued: 2008
- Authors: Hayward, Brett A , Amos, Trevor L , Baxter, Jeremy
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270077 , vital:54393 , xlink:href="https://hdl.handle.net/10520/EJC17031"
- Description: Purpose: The purpose of this research is to explore the relationship between employee performance, leadership style and emotional intelligence in the context of a South African parastatal. Problem Investigated: There is a lack of literature and empirical research on the type of leadership required to achieve high levels of employee performance within South African parastatals. Methodology: The Multifactor Leadership Questionnaire (MLQ) was used to determine leadership style, while the Emotional Competency Profiler (ECP) was used to determine the emotional intelligence of the sample of leaders. Employee performance data was provided by the parastatal, based on their performance management system. Data was analysed using correlation analysis, multiple regression analysis, the standard regression ANOVA/F-test, t-tests and Cronbach alpha reliability coefficient. Findings: The findings of the research show that the ECP is a reliable measure of emotional intelligence and that while the MLQ is a reliable measure of transformational leadership, it is not a reliable measure of transactional leadership. The results of the correlation analysis show a positive significant relationship between emotional intelligence and transformational leadership and a negative significant relationship between employee performance and emotional intelligence. The results of regressing employee performance on emotional intelligence and transformational leadership show that emotional intelligence and transformational leadership have no significant effect on employee performance. The results of the regression models of the research could be biased by the lack of variance in employee performance data. Value of the Research: The value of the research lies in it confirming the MLQ as a reliable measure of transformational leadership and the ECP as a reliable measure of emotional intelligence. The finding of a positive significant relationship between emotional intelligence and transformational leadership is a valuable contribution to the literature. Conclusion: Although a positive significant relationship between emotional intelligence and transformational leadership was found, there is a need for further research to determine the type of leadership best suited to achieve high levels of employee performance within the parastatal.
- Full Text:
- Date Issued: 2008
Energy transfer in zinc porphyrin–phthalocyanine heterotrimer and heterononamer studied by fluorescence resonance energy transfer (FRET)
- Durmus, Mahmut, Chen, Jiyao Y, Zhao, Zhixin X, Nyokong, Tebello
- Authors: Durmus, Mahmut , Chen, Jiyao Y , Zhao, Zhixin X , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268599 , vital:54213 , xlink:href="https://doi.org/10.1016/j.saa.2007.07.010"
- Description: Two or eight zinc triphenyl porphyrins were conjugated with Zn-phthalocyanine or H2-phthalocyanine to form ZnPc–(ZnTPP)2, ZnPc–(ZnTPP)8, H2Pc–(ZnTPP)2 and H2Pc–(ZnTPP)8. Energy transfers from the porphyrin moiety to phthalocyanine part were quantitatively studied with the modality of fluorescence resonance energy transfer (FRET). By measuring the fluorescence increment from the phthalocyanine moiety and the decrease from porphyrin part under selective excitation at the B band of the porphyrin part in those conjugated compounds and their equimolar mixture of compositions, energy transfer efficiencies were estimated to be 90% for H2Pc–(ZnTPP)8 and ZnPc–(ZnTPP)8, and 60%, 30% for ZnPc–(ZnTPP)2 and H2Pc–(ZnTPP)2, respectively.
- Full Text:
- Date Issued: 2008
- Authors: Durmus, Mahmut , Chen, Jiyao Y , Zhao, Zhixin X , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268599 , vital:54213 , xlink:href="https://doi.org/10.1016/j.saa.2007.07.010"
- Description: Two or eight zinc triphenyl porphyrins were conjugated with Zn-phthalocyanine or H2-phthalocyanine to form ZnPc–(ZnTPP)2, ZnPc–(ZnTPP)8, H2Pc–(ZnTPP)2 and H2Pc–(ZnTPP)8. Energy transfers from the porphyrin moiety to phthalocyanine part were quantitatively studied with the modality of fluorescence resonance energy transfer (FRET). By measuring the fluorescence increment from the phthalocyanine moiety and the decrease from porphyrin part under selective excitation at the B band of the porphyrin part in those conjugated compounds and their equimolar mixture of compositions, energy transfer efficiencies were estimated to be 90% for H2Pc–(ZnTPP)8 and ZnPc–(ZnTPP)8, and 60%, 30% for ZnPc–(ZnTPP)2 and H2Pc–(ZnTPP)2, respectively.
- Full Text:
- Date Issued: 2008
Environmental Education and Educational Quality and Relevance-Opening the debate
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182668 , vital:43852 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122756"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) tackles a critical issue being debated across the world today, namely the question of educational quality and relevance. In 2005 the UNESCO Education for All Global Monitoring Report entitled Education for All: The Quality Imperative (UNESCO, 2004) was published. This global monitoring report drew attention to issues of educational quality, and raised the problem that physical access to education does not necessarily lead to epistemological access to knowledge or to relevant education being offered to learners. In the foreword to the 430-page assessment of educational quality issues, Koïchiro Matsuura, Director General of UNESCO, stated that ‘although much debate surrounds attempts to define educational quality, solid common ground exists … Quality must be seen in light of how societies define the purpose of education’ (UNESCO, 2004: Foreword). He went on to explain that there seem to be two mutually agreed upon purposes for education in the world today: cognitive development of learners, and creative and emotional growth of learners to help them acquire values and attitudes for responsible citizenship. He also pointed out that ‘quality must pass the test of equity’ (UNESCO, 2004: Foreword), emphasising the importance of equity of opportunity to access and participate in education and learning. Relevant to the field of environmental education, is the inclusion of educational quality as a major thrust of the United Nations Decade of Education for Sustainable Development (UNDESD) (UNESCO, 2004).
- Full Text:
- Date Issued: 2008
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182668 , vital:43852 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122756"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) tackles a critical issue being debated across the world today, namely the question of educational quality and relevance. In 2005 the UNESCO Education for All Global Monitoring Report entitled Education for All: The Quality Imperative (UNESCO, 2004) was published. This global monitoring report drew attention to issues of educational quality, and raised the problem that physical access to education does not necessarily lead to epistemological access to knowledge or to relevant education being offered to learners. In the foreword to the 430-page assessment of educational quality issues, Koïchiro Matsuura, Director General of UNESCO, stated that ‘although much debate surrounds attempts to define educational quality, solid common ground exists … Quality must be seen in light of how societies define the purpose of education’ (UNESCO, 2004: Foreword). He went on to explain that there seem to be two mutually agreed upon purposes for education in the world today: cognitive development of learners, and creative and emotional growth of learners to help them acquire values and attitudes for responsible citizenship. He also pointed out that ‘quality must pass the test of equity’ (UNESCO, 2004: Foreword), emphasising the importance of equity of opportunity to access and participate in education and learning. Relevant to the field of environmental education, is the inclusion of educational quality as a major thrust of the United Nations Decade of Education for Sustainable Development (UNDESD) (UNESCO, 2004).
- Full Text:
- Date Issued: 2008
Estimating the age of immature Chrysomya albiceps (Diptera: Calliphoridae), correcting for temperature and geographical latitude
- Richards, Cameron S, Paterson, Iain D, Villet, Martin H
- Authors: Richards, Cameron S , Paterson, Iain D , Villet, Martin H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442129 , vital:73961 , https://doi.org/10.1007/s00414-007-0201-7
- Description: Developmental curves for Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) were established at 13 different constant temperatures using developmental landmarks and length as measures of age. The thermal summation constants (K) and developmental zeros (D 0) were calculated for five developmental landmarks using the method described by Ikemoto and Takai (Environ Entomol 29:671–682, 2000). Comparison with the K and D 0 values of our findings to those of three previously published studies of C. albiceps suggests that K is directly proportional to geographic latitude, and D 0 is inversely proportional to both K and geographic latitude. Body size and developmental landmarks have a complex relationship because of trade-offs between mortality risk and female fecundity (as measured by body size) at non-optimal temperatures. This relationship can be summarized using superimposed isomorphen and isomegalen diagrams, which can then be used to make forensic estimates of postmortem intervals from larval body lengths. Finally, we recommend that future studies providing data for precise forensic estimates of postmortem intervals should use a relative temporal precision of about 10% of the total duration being measured. For many blowflies, this translates into a sampling interval of approximately every 2 h before hatching, 3 h before first ecdysis and 6 h before second ecdysis.
- Full Text:
- Date Issued: 2008
- Authors: Richards, Cameron S , Paterson, Iain D , Villet, Martin H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442129 , vital:73961 , https://doi.org/10.1007/s00414-007-0201-7
- Description: Developmental curves for Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) were established at 13 different constant temperatures using developmental landmarks and length as measures of age. The thermal summation constants (K) and developmental zeros (D 0) were calculated for five developmental landmarks using the method described by Ikemoto and Takai (Environ Entomol 29:671–682, 2000). Comparison with the K and D 0 values of our findings to those of three previously published studies of C. albiceps suggests that K is directly proportional to geographic latitude, and D 0 is inversely proportional to both K and geographic latitude. Body size and developmental landmarks have a complex relationship because of trade-offs between mortality risk and female fecundity (as measured by body size) at non-optimal temperatures. This relationship can be summarized using superimposed isomorphen and isomegalen diagrams, which can then be used to make forensic estimates of postmortem intervals from larval body lengths. Finally, we recommend that future studies providing data for precise forensic estimates of postmortem intervals should use a relative temporal precision of about 10% of the total duration being measured. For many blowflies, this translates into a sampling interval of approximately every 2 h before hatching, 3 h before first ecdysis and 6 h before second ecdysis.
- Full Text:
- Date Issued: 2008
Evaluating and improving morpho-syntactic classification over multiple corpora using pre-trained, off-the-shelf, parts-of-speech tagging tools reviewed article
- Glass, Kevin R, Bangay, Shaun D
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433427 , vital:72969 , https://hdl.handle.net/10520/EJC28053
- Description: This paper evaluates six commonly available parts-of-speech tagging tools over corpora other than those upon which they were originally trained. In particular this investigation measures the performance of the selected tools over varying styles and genres of text without retraining, under the assumption that domain specific training data is not always available. An investigation is performed to determine whether improved results can be achieved by combining the set of tagging tools into ensembles that use voting schemes to determine the best tag for each word. It is found that while accuracy drops due to non-domain specific training, and tag-mapping between corpora, accuracy remains very high, with the support vector machine-based tagger, and the decision tree-based tagger performing best over different corpora. It is also found that an ensemble containing a support vector machine-based tagger, a probabilistic tagger, a decision-tree based tagger and a rule-based tagger produces the largest increase in accuracy and the largest reduction in error across different corpora, using the Precision-Recall voting scheme.
- Full Text:
- Date Issued: 2008
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433427 , vital:72969 , https://hdl.handle.net/10520/EJC28053
- Description: This paper evaluates six commonly available parts-of-speech tagging tools over corpora other than those upon which they were originally trained. In particular this investigation measures the performance of the selected tools over varying styles and genres of text without retraining, under the assumption that domain specific training data is not always available. An investigation is performed to determine whether improved results can be achieved by combining the set of tagging tools into ensembles that use voting schemes to determine the best tag for each word. It is found that while accuracy drops due to non-domain specific training, and tag-mapping between corpora, accuracy remains very high, with the support vector machine-based tagger, and the decision tree-based tagger performing best over different corpora. It is also found that an ensemble containing a support vector machine-based tagger, a probabilistic tagger, a decision-tree based tagger and a rule-based tagger produces the largest increase in accuracy and the largest reduction in error across different corpora, using the Precision-Recall voting scheme.
- Full Text:
- Date Issued: 2008
Factors affecting accuracy and precision of thermal summation models of insect development used to estimate post-mortem intervals
- Richards, Cameron S, Villet, Martin H
- Authors: Richards, Cameron S , Villet, Martin H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442142 , vital:73962 , https://doi.org/10.1007/s00414-008-0243-5
- Description: This paper investigates the effects that different summary statistics (minimum, median, mean, or maximum), temporal sampling resolutions (duration between sampling events), and sample sizes (number of individuals sampled per sampling event) had on the accuracy and precision of the regression coefficients of a typical thermal summation model used to calculate minimum post-mortem interval (PMI). No significant differences were found in the values of the developmental constants calculated from different summary statistics of the duration of development. Sample size was found to affect the precision of measurement of the duration of development but had little overall influence on thermal summation constant (K) and developmental threshold (D 0) calculations (and therefore, subsequent PMI estimates), but temporal sampling resolution had a direct influence on the accuracy of K and D 0 calculations. These data suggest that when numbers of experimental maggots are limited, it is more important to sample more frequently using smaller sample sizes than to sample less frequently with large sample sizes. Furthermore, we suggest that the median is the most representative summary measure of the duration of development and should be used preferentially.
- Full Text:
- Date Issued: 2008
- Authors: Richards, Cameron S , Villet, Martin H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442142 , vital:73962 , https://doi.org/10.1007/s00414-008-0243-5
- Description: This paper investigates the effects that different summary statistics (minimum, median, mean, or maximum), temporal sampling resolutions (duration between sampling events), and sample sizes (number of individuals sampled per sampling event) had on the accuracy and precision of the regression coefficients of a typical thermal summation model used to calculate minimum post-mortem interval (PMI). No significant differences were found in the values of the developmental constants calculated from different summary statistics of the duration of development. Sample size was found to affect the precision of measurement of the duration of development but had little overall influence on thermal summation constant (K) and developmental threshold (D 0) calculations (and therefore, subsequent PMI estimates), but temporal sampling resolution had a direct influence on the accuracy of K and D 0 calculations. These data suggest that when numbers of experimental maggots are limited, it is more important to sample more frequently using smaller sample sizes than to sample less frequently with large sample sizes. Furthermore, we suggest that the median is the most representative summary measure of the duration of development and should be used preferentially.
- Full Text:
- Date Issued: 2008
Flock inspired area coverage using wireless boid-like sensor agents
- Chibaya, Colin, Bangay, Shaun D
- Authors: Chibaya, Colin , Bangay, Shaun D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433440 , vital:72970 , 10.1109/UKSIM.2008.102
- Description: Simulated flocking is achievable using three boid rules [13]. We propose an area coverage model inspired by Reynolds’ flocking algorithm, investigating strategies for achieving quality coverage using flocking rules. Our agents are identical and autonomous, using only local sensory information for indirect communication. Upon deployment, agents are in the default separation mode. The cohesion rule would then guarantee that agents remain within the swarm, covering spaces with explored neighbour spaces. Four experiments are conducted to evaluate our model in terms of coverage quality achieved. We firstly investigate agents’ separation speed before the speed with which isolated agents re-organizes is investigated. The third experiment compares coverage quality achieved using our model with coverage quality achieved using random guessing. Finally, we investigate fault tolerance in the event of agents’ failures. Our model exhibits good separation and cohesion speed, achieving high quality coverage. Additionally, the model is fault tolerant and adaptive to agents’ failures.
- Full Text:
- Date Issued: 2008
- Authors: Chibaya, Colin , Bangay, Shaun D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433440 , vital:72970 , 10.1109/UKSIM.2008.102
- Description: Simulated flocking is achievable using three boid rules [13]. We propose an area coverage model inspired by Reynolds’ flocking algorithm, investigating strategies for achieving quality coverage using flocking rules. Our agents are identical and autonomous, using only local sensory information for indirect communication. Upon deployment, agents are in the default separation mode. The cohesion rule would then guarantee that agents remain within the swarm, covering spaces with explored neighbour spaces. Four experiments are conducted to evaluate our model in terms of coverage quality achieved. We firstly investigate agents’ separation speed before the speed with which isolated agents re-organizes is investigated. The third experiment compares coverage quality achieved using our model with coverage quality achieved using random guessing. Finally, we investigate fault tolerance in the event of agents’ failures. Our model exhibits good separation and cohesion speed, achieving high quality coverage. Additionally, the model is fault tolerant and adaptive to agents’ failures.
- Full Text:
- Date Issued: 2008
Forensic Entomology: An Introduction, D.E. Gennard book: review
- Villet, Martin H, Richards, Cameron S
- Authors: Villet, Martin H , Richards, Cameron S
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451690 , vital:75070 , https://hdl.handle.net/10520/EJC32766
- Description: Since the publication of Smith's (1986) "A manual of forensic entomology", there have been a series of useful texts in forensic entomology, some written as authoritative resources (Byrd and Castner 2001; Greenberg and Kunish 2002; Wyss and Cherix 2006) and others as training manuals (Catts and Haskell 1990). Dorothy Gennard's contribution is a bit of both, being the first text written primarily as a broad introduction to medico-criminal forensic entomology for specialised undergraduate classes.
- Full Text:
- Date Issued: 2008
- Authors: Villet, Martin H , Richards, Cameron S
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451690 , vital:75070 , https://hdl.handle.net/10520/EJC32766
- Description: Since the publication of Smith's (1986) "A manual of forensic entomology", there have been a series of useful texts in forensic entomology, some written as authoritative resources (Byrd and Castner 2001; Greenberg and Kunish 2002; Wyss and Cherix 2006) and others as training manuals (Catts and Haskell 1990). Dorothy Gennard's contribution is a bit of both, being the first text written primarily as a broad introduction to medico-criminal forensic entomology for specialised undergraduate classes.
- Full Text:
- Date Issued: 2008
Guidelines for Constructing Robust Discrete-Time Computer Network Simulations
- Richter, John, Irwin, Barry V W
- Authors: Richter, John , Irwin, Barry V W
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429896 , vital:72649 , https://doi.org/10.1007/978-1-4020-8737-0_69
- Description: Developing network simulations is a complex task that is often per-formed in research and testing. The components required to build a network simulator are common to many solutions. In order to expedite further simulation development, these components have been outlined and detailed in this paper. The process for generating and using these components is then detailed, and an example of a simulator that has been implemented using this system, is detailed
- Full Text:
- Date Issued: 2008
- Authors: Richter, John , Irwin, Barry V W
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429896 , vital:72649 , https://doi.org/10.1007/978-1-4020-8737-0_69
- Description: Developing network simulations is a complex task that is often per-formed in research and testing. The components required to build a network simulator are common to many solutions. In order to expedite further simulation development, these components have been outlined and detailed in this paper. The process for generating and using these components is then detailed, and an example of a simulator that has been implemented using this system, is detailed
- Full Text:
- Date Issued: 2008
Herbivory-induced reduction in photosynthetic productivity of water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), is not directly related to reduction in photosynthetic leaf areas
- Ripley, Bradford S, deWet, L, Hill, Martin P
- Authors: Ripley, Bradford S , deWet, L , Hill, Martin P
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451425 , vital:75048 , https://hdl.handle.net/10520/EJC32746
- Description: The purpose of this investigation was to determine whether the reduced photosynthetic productivity of water hyacinth plants subject to N. eichhorniae adult feeding was simply the result of reduced leaf area, or if more complex mechanisms were involved.
- Full Text:
- Date Issued: 2008
- Authors: Ripley, Bradford S , deWet, L , Hill, Martin P
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451425 , vital:75048 , https://hdl.handle.net/10520/EJC32746
- Description: The purpose of this investigation was to determine whether the reduced photosynthetic productivity of water hyacinth plants subject to N. eichhorniae adult feeding was simply the result of reduced leaf area, or if more complex mechanisms were involved.
- Full Text:
- Date Issued: 2008
High level internet scale traffic visualization using hilbert curve mapping
- Irwin, Barry V W, Pilkington, Nick
- Authors: Irwin, Barry V W , Pilkington, Nick
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429911 , vital:72650 , https://doi.org/10.1007/978-3-540-78243-8_10
- Description: A high level analysis tool was developed for aiding in the analysis of large volumes of network telescope traffic, and in particular the comparisons of data col-lected from multiple telescope sources. Providing a visual means for the evaluation of worm propagation algorithms has also been achieved. By using a Hilbert curve as a means of ordering points within the visual-ization space, the concept of nearness between nu-merically sequential network blocks was preserved. The design premise and initial results obtained using the tool developed are discussed, and a number of fu-ture extensions proposed.
- Full Text:
- Date Issued: 2008
- Authors: Irwin, Barry V W , Pilkington, Nick
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429911 , vital:72650 , https://doi.org/10.1007/978-3-540-78243-8_10
- Description: A high level analysis tool was developed for aiding in the analysis of large volumes of network telescope traffic, and in particular the comparisons of data col-lected from multiple telescope sources. Providing a visual means for the evaluation of worm propagation algorithms has also been achieved. By using a Hilbert curve as a means of ordering points within the visual-ization space, the concept of nearness between nu-merically sequential network blocks was preserved. The design premise and initial results obtained using the tool developed are discussed, and a number of fu-ture extensions proposed.
- Full Text:
- Date Issued: 2008
in a park in Europe
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229851 , vital:49717 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229851 , vital:49717 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
in the council chambers
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229862 , vital:49718 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229862 , vital:49718 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
Interaction of water-soluble thiol capped CdTe quantum dots and bovine serum albumin
- Idowu, Mopelola, Lamprecht, Emmanuel, Nyokong, Tebello
- Authors: Idowu, Mopelola , Lamprecht, Emmanuel , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265974 , vital:53906 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.02.008"
- Description: Luminescent water-soluble CdTe quantum dots (QDs) capped with different thiol carboxylic acids were synthesized in aqueous medium and then cross linked to bovine serum albumin (BSA) with 1-ethyl3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Enhancement of fluorescence emission intensity occurred for QDs in the presence of bovine serum albumin (BSA, mixed or linked) signifying inhibition of non-radiative recombination of the surface vacancies. Fluorescence studies reveal a positive deviation behaviour suggesting the occurrence of static and dynamic mechanisms of quenching together which was accounted for by the modified Stern–Volmer equation.
- Full Text:
- Date Issued: 2008
- Authors: Idowu, Mopelola , Lamprecht, Emmanuel , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265974 , vital:53906 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.02.008"
- Description: Luminescent water-soluble CdTe quantum dots (QDs) capped with different thiol carboxylic acids were synthesized in aqueous medium and then cross linked to bovine serum albumin (BSA) with 1-ethyl3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Enhancement of fluorescence emission intensity occurred for QDs in the presence of bovine serum albumin (BSA, mixed or linked) signifying inhibition of non-radiative recombination of the surface vacancies. Fluorescence studies reveal a positive deviation behaviour suggesting the occurrence of static and dynamic mechanisms of quenching together which was accounted for by the modified Stern–Volmer equation.
- Full Text:
- Date Issued: 2008
Jantjie v The Minister of Labour Unreported Eastern Cape Division Case No 2193/2006
- Authors: Glover, Graham B , Beard, M
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186891 , vital:44545 , xlink:href="///C:/Users/User/Downloads/41DeJure648%20(1).pdf"
- Description: James Joyce once wrote that "mistakes ... are the portals of discovery" (Ulysses (1964) Ch 9). This aptly describes the legal significance of the judgment in Jantjie v Minister of Labour (unreported decision of the High Court, Eastern Cape Division, case no 3193/2006, decided on 2007-06- 14). In this case, Leach J had to deal with a matter of civil procedure that does not seem to have been dealt with in any reported judgment - the effect of an attorney of record mistakenly failing to sign a notice of motion where an application is brought before the High Court.
- Full Text:
- Date Issued: 2008
- Authors: Glover, Graham B , Beard, M
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186891 , vital:44545 , xlink:href="///C:/Users/User/Downloads/41DeJure648%20(1).pdf"
- Description: James Joyce once wrote that "mistakes ... are the portals of discovery" (Ulysses (1964) Ch 9). This aptly describes the legal significance of the judgment in Jantjie v Minister of Labour (unreported decision of the High Court, Eastern Cape Division, case no 3193/2006, decided on 2007-06- 14). In this case, Leach J had to deal with a matter of civil procedure that does not seem to have been dealt with in any reported judgment - the effect of an attorney of record mistakenly failing to sign a notice of motion where an application is brought before the High Court.
- Full Text:
- Date Issued: 2008
Juvenile population dynamics of Oreochromis mossambicus in an intermittently open estuary at the limit of its natural distribution
- Ellender, Bruce R, Weyl, Olaf L F, Shanyengange, M K, Cowley, Paul D
- Authors: Ellender, Bruce R , Weyl, Olaf L F , Shanyengange, M K , Cowley, Paul D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446893 , vital:74568 , https://doi.org/10.1080/15627020.2008.11657245
- Description: Juvenile Oreochromis mossambicus in the 25 ha, temperate, intermittently open, East Kleinemonde Estuary in the Eastern Cape, South Africa (33°32’S, 27°03’E), showed a seasonal shift in distribution, occupying all areas of the estuary in summer and, subsequently, being limited to the upper reaches in winter. The young of the year in the littoral zone were rapidly depleted and resultant estimates of the instantaneous rate of total mortality (Z) ranged from 5.4/yr to 6.9/yr. High annual rates of juvenile mortality and small adult populations imply that stock recovery after a reduction in adult population numbers, through activities such as fishing, may be slow. This work adds to the knowledge base of O. mossambicus ecology and population dynamics in temperate estuaries at the limit of its natural distribution.
- Full Text:
- Date Issued: 2008
- Authors: Ellender, Bruce R , Weyl, Olaf L F , Shanyengange, M K , Cowley, Paul D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446893 , vital:74568 , https://doi.org/10.1080/15627020.2008.11657245
- Description: Juvenile Oreochromis mossambicus in the 25 ha, temperate, intermittently open, East Kleinemonde Estuary in the Eastern Cape, South Africa (33°32’S, 27°03’E), showed a seasonal shift in distribution, occupying all areas of the estuary in summer and, subsequently, being limited to the upper reaches in winter. The young of the year in the littoral zone were rapidly depleted and resultant estimates of the instantaneous rate of total mortality (Z) ranged from 5.4/yr to 6.9/yr. High annual rates of juvenile mortality and small adult populations imply that stock recovery after a reduction in adult population numbers, through activities such as fishing, may be slow. This work adds to the knowledge base of O. mossambicus ecology and population dynamics in temperate estuaries at the limit of its natural distribution.
- Full Text:
- Date Issued: 2008