'We pledge to improve the health of our entire community'
- Grant, Carolyn, Nawal, Dipty, Guntur, Sai Mala, Kumar, Manish, Chaudhuri, Indrajit, Galavotti, Christine, Mahapatra, Tanmay, Ranjan, Kunal, Kumar, Gangesh, Mohanty, Sunil, Alam, Mohammed Aftab, Das, Aritra, Jiwani, Safia
- Authors: Grant, Carolyn , Nawal, Dipty , Guntur, Sai Mala , Kumar, Manish , Chaudhuri, Indrajit , Galavotti, Christine , Mahapatra, Tanmay , Ranjan, Kunal , Kumar, Gangesh , Mohanty, Sunil , Alam, Mohammed Aftab , Das, Aritra , Jiwani, Safia
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281179 , vital:55699 , xlink:href="https://doi.org/10.1371/journal.pone.0203265"
- Description: Background: Motivation is critical to health worker performance and work quality. In Bihar, India, frontline health workers provide essential health services for the state’s poorest citizens. Yet, there is a shortfall of motivated and skilled providers and a lack of coordination between two cadres of frontline health workers and their supervisors. CARE India developed an approach aimed at improving health workers’ performance by shifting work culture and strengthening teamwork and motivation. The intervention—“Team-Based Goals and Incentives”—supported health workers to work as teams towards collective goals and rewarded success with public recognition and non-financial incentives. Methods: Thirty months after initiating the intervention, 885 health workers and 98 supervisors completed an interviewer-administered questionnaire in 38 intervention and 38 control health sub-centers in one district. The questionnaire included measures of social cohesion, teamwork attitudes, self-efficacy, job satisfaction, teamwork behaviors, equitable service delivery, taking initiative, and supervisory support. We conducted bivariate analyses to examine the impact of the intervention on these psychosocial and behavioral outcomes. Results: Results show statistically significant differences across several measures between intervention and control frontline health workers, including improved teamwork (mean = 8.8 vs. 7.3), empowerment (8.5 vs. 7.4), job satisfaction (7.1 vs. 5.99) and equitable service delivery (6.7 vs. 4.99). While fewer significant differences were found for supervisors, they reported improved teamwork (8.4 vs. 5.3), and frontline health workers reported improved fulfillment of supervisory duties by their supervisors (8.9 vs. 7.6). Both frontline health workers and supervisors found public recognition and enhanced teamwork more motivating than the non-financial incentives. Conclusions: The Team-Based Goals and Incentives model reinforces intrinsic motivation and supports improvements in the teamwork, motivation, and performance of health workers. It offers an approach to practitioners and governments for improving the work environment in a resource-constrained setting and where there are multiple cadres of health workers.
- Full Text:
- Date Issued: 2018
- Authors: Grant, Carolyn , Nawal, Dipty , Guntur, Sai Mala , Kumar, Manish , Chaudhuri, Indrajit , Galavotti, Christine , Mahapatra, Tanmay , Ranjan, Kunal , Kumar, Gangesh , Mohanty, Sunil , Alam, Mohammed Aftab , Das, Aritra , Jiwani, Safia
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281179 , vital:55699 , xlink:href="https://doi.org/10.1371/journal.pone.0203265"
- Description: Background: Motivation is critical to health worker performance and work quality. In Bihar, India, frontline health workers provide essential health services for the state’s poorest citizens. Yet, there is a shortfall of motivated and skilled providers and a lack of coordination between two cadres of frontline health workers and their supervisors. CARE India developed an approach aimed at improving health workers’ performance by shifting work culture and strengthening teamwork and motivation. The intervention—“Team-Based Goals and Incentives”—supported health workers to work as teams towards collective goals and rewarded success with public recognition and non-financial incentives. Methods: Thirty months after initiating the intervention, 885 health workers and 98 supervisors completed an interviewer-administered questionnaire in 38 intervention and 38 control health sub-centers in one district. The questionnaire included measures of social cohesion, teamwork attitudes, self-efficacy, job satisfaction, teamwork behaviors, equitable service delivery, taking initiative, and supervisory support. We conducted bivariate analyses to examine the impact of the intervention on these psychosocial and behavioral outcomes. Results: Results show statistically significant differences across several measures between intervention and control frontline health workers, including improved teamwork (mean = 8.8 vs. 7.3), empowerment (8.5 vs. 7.4), job satisfaction (7.1 vs. 5.99) and equitable service delivery (6.7 vs. 4.99). While fewer significant differences were found for supervisors, they reported improved teamwork (8.4 vs. 5.3), and frontline health workers reported improved fulfillment of supervisory duties by their supervisors (8.9 vs. 7.6). Both frontline health workers and supervisors found public recognition and enhanced teamwork more motivating than the non-financial incentives. Conclusions: The Team-Based Goals and Incentives model reinforces intrinsic motivation and supports improvements in the teamwork, motivation, and performance of health workers. It offers an approach to practitioners and governments for improving the work environment in a resource-constrained setting and where there are multiple cadres of health workers.
- Full Text:
- Date Issued: 2018
A critical review of sanctioned knowledge production concerning abortion in Africa: Implications for feminist health psychology
- Macleod, Catriona I, Chiweshe, Malvern T, Mavuso, Jabulile M-J J
- Authors: Macleod, Catriona I , Chiweshe, Malvern T , Mavuso, Jabulile M-J J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444212 , vital:74207 , xlink:href="https://doi.org/10.1177/1359105316644294"
- Description: Taking a feminist health psychology approach, we conducted a systematic review of published research on abortion featured in PsycINFO over a 7-year period. We analysed the 39 articles included in the review in terms of countries in which the research was conducted, types of research, issues covered, the way the research was framed and main findings. Despite 97per cent of abortions performed in Africa being classifiable as unsafe, there has been no engagement in knowledge production about abortion in Africa from psychologists, outside of South Africa. Given this, we outline the implications of the current knowledge base for feminism, psychology and feminist health psychology in Africa.
- Full Text:
- Date Issued: 2018
- Authors: Macleod, Catriona I , Chiweshe, Malvern T , Mavuso, Jabulile M-J J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444212 , vital:74207 , xlink:href="https://doi.org/10.1177/1359105316644294"
- Description: Taking a feminist health psychology approach, we conducted a systematic review of published research on abortion featured in PsycINFO over a 7-year period. We analysed the 39 articles included in the review in terms of countries in which the research was conducted, types of research, issues covered, the way the research was framed and main findings. Despite 97per cent of abortions performed in Africa being classifiable as unsafe, there has been no engagement in knowledge production about abortion in Africa from psychologists, outside of South Africa. Given this, we outline the implications of the current knowledge base for feminism, psychology and feminist health psychology in Africa.
- Full Text:
- Date Issued: 2018
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 peaceful revenge: Achieving structural and agential transformation in a South African context using cognitive justice and emancipatory social learning
- Authors: Burt, Jane C , James, Anna
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392049 , vital:68717 , xlink:href="https://doi.org/10.1080/14767430.2018.1550312"
- Description: This is an account of the emancipatory struggle that faces agents who seek to change the oppressive social structures associated with neo-liberalism. We begin by ‘digging amongst the bones’ of the calls for resistance that have been declared dead or assimilated/co-opted by neoliberal theorists. This leads us to unearth, then utilize, Paulo Freire’s Pedagogy of the Oppressed, Steve Biko’s Black Consciousness and Shiv Visvanathan's ideas; which are examples of Roy Bhaskar’s transformative dialectic. We argue, using examples, that cognitive justice – a concept common to each of our chosen theorists – is vital in enabling emancipatory social learning. By embracing cognitive justice, the agents gained confidence, which led to their increased ability to champion community and non-academic knowledge. It also uncovered structural tensions – attendant in neoliberalism – around privilege. By articulating these tensions, the participants were able to ‘come closer together’. Such processes, initiated by ensuring cognitive justice, are possible steps in achieving universal solidarity; which is likely to be a necessary step along the path of achieving emancipation.
- Full Text:
- Date Issued: 2018
- Authors: Burt, Jane C , James, Anna
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392049 , vital:68717 , xlink:href="https://doi.org/10.1080/14767430.2018.1550312"
- Description: This is an account of the emancipatory struggle that faces agents who seek to change the oppressive social structures associated with neo-liberalism. We begin by ‘digging amongst the bones’ of the calls for resistance that have been declared dead or assimilated/co-opted by neoliberal theorists. This leads us to unearth, then utilize, Paulo Freire’s Pedagogy of the Oppressed, Steve Biko’s Black Consciousness and Shiv Visvanathan's ideas; which are examples of Roy Bhaskar’s transformative dialectic. We argue, using examples, that cognitive justice – a concept common to each of our chosen theorists – is vital in enabling emancipatory social learning. By embracing cognitive justice, the agents gained confidence, which led to their increased ability to champion community and non-academic knowledge. It also uncovered structural tensions – attendant in neoliberalism – around privilege. By articulating these tensions, the participants were able to ‘come closer together’. Such processes, initiated by ensuring cognitive justice, are possible steps in achieving universal solidarity; which is likely to be a necessary step along the path of achieving emancipation.
- Full Text:
- Date Issued: 2018
A preliminary study of minimal-contention locks
- Machanick, Philip, Mbiyavanga, Mamana
- Authors: Machanick, Philip , Mbiyavanga, Mamana
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439093 , vital:73544 , https://doi.org/10.1145/3278681.3278713
- Description: As multicore CPUs become more common, scalable synchronization primitives have wider use and ideas previously used in large-scale computation are worth re-opening for wider use. In this paper I explore one approach to scalable synchronization, a minimal-contention lock (M-lock). The key idea is to avoid spinning on a global variable but instead for each blocked task (process or thread) to spin on a local lock representing the task that immediately preceded it in attempting to acquire the lock. This creates an ordering based on the order in which tasks attempt to acquire the lock, preventing starvation. The only globally shared variable is a pointer to the next local lock to be contended for. Each contending task swaps the value of this pointer for a pointer to its own variable. It spins on the variable previously pointed to by the global pointer. Each waiting task spins on a lock only seen by itself and the owner of that lock variable. While a task is spinning, the lock variable can be held in its local cache until invalidated by the lock owner when it unsets the lock. Consequently, the amount of bus traffic is considerably less than with a spinlock, which has the pernicious feature that the task releasing the lock is delayed by all the other bus traffic arising from contention for the lock. An MCS lock has similar properties but is more complicated and requires more memory contention-causing operations. This paper outlines the design of the M-lock and provides a preliminary performance analysis.
- Full Text:
- Date Issued: 2018
- Authors: Machanick, Philip , Mbiyavanga, Mamana
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439093 , vital:73544 , https://doi.org/10.1145/3278681.3278713
- Description: As multicore CPUs become more common, scalable synchronization primitives have wider use and ideas previously used in large-scale computation are worth re-opening for wider use. In this paper I explore one approach to scalable synchronization, a minimal-contention lock (M-lock). The key idea is to avoid spinning on a global variable but instead for each blocked task (process or thread) to spin on a local lock representing the task that immediately preceded it in attempting to acquire the lock. This creates an ordering based on the order in which tasks attempt to acquire the lock, preventing starvation. The only globally shared variable is a pointer to the next local lock to be contended for. Each contending task swaps the value of this pointer for a pointer to its own variable. It spins on the variable previously pointed to by the global pointer. Each waiting task spins on a lock only seen by itself and the owner of that lock variable. While a task is spinning, the lock variable can be held in its local cache until invalidated by the lock owner when it unsets the lock. Consequently, the amount of bus traffic is considerably less than with a spinlock, which has the pernicious feature that the task releasing the lock is delayed by all the other bus traffic arising from contention for the lock. An MCS lock has similar properties but is more complicated and requires more memory contention-causing operations. This paper outlines the design of the M-lock and provides a preliminary performance analysis.
- Full Text:
- Date Issued: 2018
Arbuscular mycorrhizal fungi persist in dying Euphorbia ingens trees
- Vivas, M, Crous, C J, Dames, Joanna F, van der Linde, J A, Coetzee, M P A, Roux, J
- Authors: Vivas, M , Crous, C J , Dames, Joanna F , van der Linde, J A , Coetzee, M P A , Roux, J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440465 , vital:73784 , https://doi.org/10.1016/j.sajb.2017.12.009
- Description: Forest declines have been reported with increasing regularity during the last decade and are expected to increase due to the ongoing environmental changes. During adverse environmental conditions, plant symbioses with mycorrhizas can help to reduce plant stress. Mycorrhizas are symbiotic associations between fungi and roots of living plants. Plants offer carbohydrates to the fungus and the fungus improves the acquisition of nutrients and water to the plant. Specifically, arbuscular mycorrhizal (AM) fungi are the most abundant mycorrhizas. In South Africa, there are increasing reports describing the decline of native Euphorbia ingens trees. This study analysed the presence and abundance of AM fungal colonisation in the roots of E. ingens trees, and the number of AM fungal spores in the surrounding soil, with the aim to improve the understanding of the rapid decline of these trees. AM fungal colonisation and spores in relation to the soil properties were also analysed. Soil and root samples were collected from different rates of declining E. ingens trees at three sites in South Africa. AM fungal colonisation of the roots was assessed and fungal spores in the surrounding soil were enumerated. Soil phosphorus, mineral nitrogen and pH were analysed from the soil samples. The results showed that AM fungi are associated with E. ingens trees. AM abundance was influenced by site specific properties and not by E. ingens health. Moreover, the level of soil NO3− and soil texture significantly influenced AM colonisation in roots and the number of spores enumerated. These preliminary findings provide background information for further research into the large-scale decline of E. ingens populations in South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Vivas, M , Crous, C J , Dames, Joanna F , van der Linde, J A , Coetzee, M P A , Roux, J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440465 , vital:73784 , https://doi.org/10.1016/j.sajb.2017.12.009
- Description: Forest declines have been reported with increasing regularity during the last decade and are expected to increase due to the ongoing environmental changes. During adverse environmental conditions, plant symbioses with mycorrhizas can help to reduce plant stress. Mycorrhizas are symbiotic associations between fungi and roots of living plants. Plants offer carbohydrates to the fungus and the fungus improves the acquisition of nutrients and water to the plant. Specifically, arbuscular mycorrhizal (AM) fungi are the most abundant mycorrhizas. In South Africa, there are increasing reports describing the decline of native Euphorbia ingens trees. This study analysed the presence and abundance of AM fungal colonisation in the roots of E. ingens trees, and the number of AM fungal spores in the surrounding soil, with the aim to improve the understanding of the rapid decline of these trees. AM fungal colonisation and spores in relation to the soil properties were also analysed. Soil and root samples were collected from different rates of declining E. ingens trees at three sites in South Africa. AM fungal colonisation of the roots was assessed and fungal spores in the surrounding soil were enumerated. Soil phosphorus, mineral nitrogen and pH were analysed from the soil samples. The results showed that AM fungi are associated with E. ingens trees. AM abundance was influenced by site specific properties and not by E. ingens health. Moreover, the level of soil NO3− and soil texture significantly influenced AM colonisation in roots and the number of spores enumerated. These preliminary findings provide background information for further research into the large-scale decline of E. ingens populations in South Africa.
- Full Text:
- Date Issued: 2018
Avian thermoregulation in the heat: is evaporative cooling more economical in nocturnal birds?
- O'Connor, Ryan S, Smit, Ben, Talbot, William A, Gerson, Alexander R, Brigham, R Mark, Wolf, Blair O, McKechnie, Andrew E
- Authors: O'Connor, Ryan S , Smit, Ben , Talbot, William A , Gerson, Alexander R , Brigham, R Mark , Wolf, Blair O , McKechnie, Andrew E
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441518 , vital:73895 , https://journals.biologists.com/jeb/article/221/17/jeb181420/19595/Avian-thermoregulation-in-the-heat-is-evaporative
- Description: Evaporative cooling is a prerequisite for avian occupancy of hot, arid environments, and is the only avenue of heat dissipation when air temperatures (Ta) exceed body temperature (Tb). Whereas diurnal birds can potentially rehydrate throughout the day, nocturnal species typically forgo drinking between sunrise and sunset. We hypothesized that nocturnal birds have evolved reduced rates of evaporative water loss (EWL) and more economical evaporative cooling mechanisms compared with diurnal species, permitting nocturnal species to tolerate extended periods of intense heat without becoming lethally dehydrated. We used phylogenetically informed regressions to compare EWL and evaporative cooling efficiency [ratio of evaporative heat loss (EHL) and metabolic heat production (MHP); EHL/MHP] among nocturnal and diurnal birds at high Ta. We analyzed variation in three response variables: (1) slope of EWL at Ta between 40 and 46°C, (2) EWL at Ta=46°C and (3) EHL/MHP at Ta=46°C. Nocturnality emerged as a weak, negative predictor, with nocturnal species having slightly shallower slopes and reduced EWL compared with diurnal species of similar mass.
- Full Text:
- Date Issued: 2018
- Authors: O'Connor, Ryan S , Smit, Ben , Talbot, William A , Gerson, Alexander R , Brigham, R Mark , Wolf, Blair O , McKechnie, Andrew E
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441518 , vital:73895 , https://journals.biologists.com/jeb/article/221/17/jeb181420/19595/Avian-thermoregulation-in-the-heat-is-evaporative
- Description: Evaporative cooling is a prerequisite for avian occupancy of hot, arid environments, and is the only avenue of heat dissipation when air temperatures (Ta) exceed body temperature (Tb). Whereas diurnal birds can potentially rehydrate throughout the day, nocturnal species typically forgo drinking between sunrise and sunset. We hypothesized that nocturnal birds have evolved reduced rates of evaporative water loss (EWL) and more economical evaporative cooling mechanisms compared with diurnal species, permitting nocturnal species to tolerate extended periods of intense heat without becoming lethally dehydrated. We used phylogenetically informed regressions to compare EWL and evaporative cooling efficiency [ratio of evaporative heat loss (EHL) and metabolic heat production (MHP); EHL/MHP] among nocturnal and diurnal birds at high Ta. We analyzed variation in three response variables: (1) slope of EWL at Ta between 40 and 46°C, (2) EWL at Ta=46°C and (3) EHL/MHP at Ta=46°C. Nocturnality emerged as a weak, negative predictor, with nocturnal species having slightly shallower slopes and reduced EWL compared with diurnal species of similar mass.
- Full Text:
- Date Issued: 2018
Avian thermoregulation in the heat: phylogenetic variation among avian orders in evaporative cooling capacity and heat tolerance
- Smit, Ben, Whitfield, Maxine C, Talbot, William A, Gerson, Alexander R, McKechnie, Andrew E, Wolf, Blair O
- Authors: Smit, Ben , Whitfield, Maxine C , Talbot, William A , Gerson, Alexander R , McKechnie, Andrew E , Wolf, Blair O
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440517 , vital:73789 , https://doi.org/10.1242/jeb.174870
- Description: Little is known about the phylogenetic variation of avian evaporative cooling efficiency and heat tolerance in hot environments. We quantified thermoregulatory responses to high air temperature (Ta) in ∼100-g representatives of three orders, namely, the African cuckoo (Cuculus gularis, Cuculiformes), lilac-breasted roller (Coracias caudatus, Coraciiformes) and Burchell's starling (Lamprotornis australis, Passeriformes). All three species initiated respiratory mechanisms to increase evaporative heat dissipation when body temperature (Tb) approached 41.5°C in response to increasing Ta, with gular flutter observed in cuckoos and panting in rollers and starlings. Resting metabolic rate and evaporative water loss increased by quantitatively similar magnitudes in all three species, although maximum rates of evaporative water loss were proportionately lower in starlings. Evaporative cooling efficiency [defined as the ratio of evaporative heat loss (EHL) to metabolic heat production (MHP)] generally remained below 2.0 in cuckoos and starlings, but reached a maximum of ∼3.5 in rollers. The high value for rollers reveals a very efficient evaporative cooling mechanism, and is similar to EHL/MHP maxima for similarly sized columbids which very effectively dissipate heat via cutaneous evaporation. This unexpected phylogenetic variation among the orders tested in the physiological mechanisms of heat dissipation is an important step toward determining the evolution of heat tolerance traits in desert birds.
- Full Text:
- Date Issued: 2018
- Authors: Smit, Ben , Whitfield, Maxine C , Talbot, William A , Gerson, Alexander R , McKechnie, Andrew E , Wolf, Blair O
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440517 , vital:73789 , https://doi.org/10.1242/jeb.174870
- Description: Little is known about the phylogenetic variation of avian evaporative cooling efficiency and heat tolerance in hot environments. We quantified thermoregulatory responses to high air temperature (Ta) in ∼100-g representatives of three orders, namely, the African cuckoo (Cuculus gularis, Cuculiformes), lilac-breasted roller (Coracias caudatus, Coraciiformes) and Burchell's starling (Lamprotornis australis, Passeriformes). All three species initiated respiratory mechanisms to increase evaporative heat dissipation when body temperature (Tb) approached 41.5°C in response to increasing Ta, with gular flutter observed in cuckoos and panting in rollers and starlings. Resting metabolic rate and evaporative water loss increased by quantitatively similar magnitudes in all three species, although maximum rates of evaporative water loss were proportionately lower in starlings. Evaporative cooling efficiency [defined as the ratio of evaporative heat loss (EHL) to metabolic heat production (MHP)] generally remained below 2.0 in cuckoos and starlings, but reached a maximum of ∼3.5 in rollers. The high value for rollers reveals a very efficient evaporative cooling mechanism, and is similar to EHL/MHP maxima for similarly sized columbids which very effectively dissipate heat via cutaneous evaporation. This unexpected phylogenetic variation among the orders tested in the physiological mechanisms of heat dissipation is an important step toward determining the evolution of heat tolerance traits in desert birds.
- Full Text:
- Date Issued: 2018
Characterization and computational studies of a co-crystal of 2-aminobenzimidazole and 2-[(benzoylcarbamothioyl) amino] propanoic acid
- Odame, Felix, Hosten, Eric C, Betz, Richard, Lobb, Kevin, Tshentu, Zenixole R
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin , Tshentu, Zenixole R
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447030 , vital:74578 , xlink:href="https://doi.org/10.1134/S0022476618050268"
- Description: A novel co-crystal of 2-aminobenzimidazole and 2-[(benzoylcarbamothioyl)amino] propanoic acid is synthesized and characterized by spectroscopy, elemental analysis, GC-MS, and single crystal XRD. A computation of the structures involved in the formation of the co-crystal are carried out and their contribution to reactivity is explained.
- Full Text:
- Date Issued: 2018
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin , Tshentu, Zenixole R
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447030 , vital:74578 , xlink:href="https://doi.org/10.1134/S0022476618050268"
- Description: A novel co-crystal of 2-aminobenzimidazole and 2-[(benzoylcarbamothioyl)amino] propanoic acid is synthesized and characterized by spectroscopy, elemental analysis, GC-MS, and single crystal XRD. A computation of the structures involved in the formation of the co-crystal are carried out and their contribution to reactivity is explained.
- Full Text:
- Date Issued: 2018
Click chemistry electrode modification using 4-ethynylbenzyl substituted cobalt phthalocyanine for applications in electrocatalysis
- Mpeta, Lekhetho S, Fomo, Gertrude, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Fomo, Gertrude , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187626 , vital:44681 , xlink:href="• https://doi.org/10.1080/00958972.2018.1466118"
- Description: In this work, we report on the synthesis and applications of a new cobalt tetrakis 4-((4-ethynylbenzyl) oxy) phthalocyanine (3) for the detection of hydrazine. The glassy carbon electrode (GCE) was first grafted through diazotization, providing the GCE surface layer with azide groups. Thereafter, the 1,3-dipolar cycloaddition reaction, catalyzed by a copper(I) catalyst was used to “click” complex 3 to the grafted surface of GCE. The new platform was then characterized using cyclic voltammetry (CV), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). This work shows that 3 is an effective sensor with sensitivity of 91.5 μA mM−1 and limit of detection of 3.28 μM which is a great improvement compared to other reported sensors for this analyte.
- Full Text:
- Date Issued: 2018
- Authors: Mpeta, Lekhetho S , Fomo, Gertrude , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187626 , vital:44681 , xlink:href="• https://doi.org/10.1080/00958972.2018.1466118"
- Description: In this work, we report on the synthesis and applications of a new cobalt tetrakis 4-((4-ethynylbenzyl) oxy) phthalocyanine (3) for the detection of hydrazine. The glassy carbon electrode (GCE) was first grafted through diazotization, providing the GCE surface layer with azide groups. Thereafter, the 1,3-dipolar cycloaddition reaction, catalyzed by a copper(I) catalyst was used to “click” complex 3 to the grafted surface of GCE. The new platform was then characterized using cyclic voltammetry (CV), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). This work shows that 3 is an effective sensor with sensitivity of 91.5 μA mM−1 and limit of detection of 3.28 μM which is a great improvement compared to other reported sensors for this analyte.
- Full Text:
- Date Issued: 2018
Comparison of physiological responses to high temperatures in juvenile and adult Cape Rockjumpers Chaetops frenatus
- Oswald, Krista N, Lee, Alan T K, Smit, Ben
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441559 , vital:73898 , https://doi.org/10.2989/00306525.2018.1509905
- Description: Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.
- Full Text:
- Date Issued: 2018
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441559 , vital:73898 , https://doi.org/10.2989/00306525.2018.1509905
- Description: Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.
- Full Text:
- Date Issued: 2018
Conjugation of isoniazid to a zinc phthalocyanine via hydrazone linkage for pH-dependent liposomal controlled release
- Nkanga, Christian, Krause, Rui W M
- Authors: Nkanga, Christian , Krause, Rui W M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/194992 , vital:45517 , xlink:href="https://doi.org/10.1007/s13204-018-0776-y"
- Description: Tuberculosis (TB) remains the leading cause of mortality from infectious diseases. Extended TB treatment and frequent adverse effects, due to poor bioavailability of anti-tubercular drugs (ATBDs), represent the main rationales behind liposomal encapsulation for controlled delivery. Liposomes have been reported as potential vehicles for targeted delivery of ATBDs due to their rapid uptake by macrophages, which are known as the main host cells for TB causative agent (Mycobacterium tuberculosis). Additionally, the need for controlled release of ATBDs arises because leakage is part of the key liposome challenges for hydrophilic compounds like isoniazid (INH). In this study, INH was conjugated to a highly hydrophobic photosensitizer, zinc (II) phthalocyanine (PC), through hydrazone bonding. The obtained conjugate (PC–INH) was encapsulated in liposomes by film hydration method. PC–INH loaded liposomes (PILs) were characterized using dynamic light scattering, transmission electron microscopy, energy-dispersive X-ray spectrometry and UV–Vis absorption spectrometry, which was used also for estimation of encapsulation efficiency (%EE). INH release was evaluated in different pH media using dialysis. Particle size, zeta potential and %EE of PILs were about 506 nm, − 55 mV and 72%, respectively. Over 12 h, PILs exhibited 22, 41, 97 and 100% of INH, respectively, released in pH 7.4, 6.4, 5.4 and 4.4 media. This pH-dependent behavior is attractive for site-specific delivery. These findings suggest the conjugation of chemotherapeutics to phthalocyanines using pH-labile linkages as a potential strategy for liposomal controlled release.
- Full Text:
- Date Issued: 2018
- Authors: Nkanga, Christian , Krause, Rui W M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/194992 , vital:45517 , xlink:href="https://doi.org/10.1007/s13204-018-0776-y"
- Description: Tuberculosis (TB) remains the leading cause of mortality from infectious diseases. Extended TB treatment and frequent adverse effects, due to poor bioavailability of anti-tubercular drugs (ATBDs), represent the main rationales behind liposomal encapsulation for controlled delivery. Liposomes have been reported as potential vehicles for targeted delivery of ATBDs due to their rapid uptake by macrophages, which are known as the main host cells for TB causative agent (Mycobacterium tuberculosis). Additionally, the need for controlled release of ATBDs arises because leakage is part of the key liposome challenges for hydrophilic compounds like isoniazid (INH). In this study, INH was conjugated to a highly hydrophobic photosensitizer, zinc (II) phthalocyanine (PC), through hydrazone bonding. The obtained conjugate (PC–INH) was encapsulated in liposomes by film hydration method. PC–INH loaded liposomes (PILs) were characterized using dynamic light scattering, transmission electron microscopy, energy-dispersive X-ray spectrometry and UV–Vis absorption spectrometry, which was used also for estimation of encapsulation efficiency (%EE). INH release was evaluated in different pH media using dialysis. Particle size, zeta potential and %EE of PILs were about 506 nm, − 55 mV and 72%, respectively. Over 12 h, PILs exhibited 22, 41, 97 and 100% of INH, respectively, released in pH 7.4, 6.4, 5.4 and 4.4 media. This pH-dependent behavior is attractive for site-specific delivery. These findings suggest the conjugation of chemotherapeutics to phthalocyanines using pH-labile linkages as a potential strategy for liposomal controlled release.
- Full Text:
- Date Issued: 2018
Contesting sexual violence policies in higher education: the case of Rhodes University
- Macleod, Catriona I, Böhmke, Werner, Barker, Kim, Mavuso, Jabulile M-J J, Chiweshe, Malvern T
- Authors: Macleod, Catriona I , Böhmke, Werner , Barker, Kim , Mavuso, Jabulile M-J J , Chiweshe, Malvern T
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444275 , vital:74212 , xlink:href="https://www.emerald.com/insight/content/doi/10.1108/JACPR-05-2017-0295/full/html"
- Description: – In April 2016, students at Rhodes University brought the institution to a standstill as they protested the University’s sexual violence policies and procedures, as well as the “rape culture” that pervades social structures. In response, a Sexual Violence Task Team (SVTT) was formed in an open, participatory, and transparent process. Members of the University community were invited to comment on drafts of the SVTT document. The purpose of this paper is to outline the contestations – arising from both the establishment of the task team and the inputs from University members to drafts of the document – that surfaced concerning managing sexual violence on campuses and sexual offences policies.
- Full Text:
- Date Issued: 2018
- Authors: Macleod, Catriona I , Böhmke, Werner , Barker, Kim , Mavuso, Jabulile M-J J , Chiweshe, Malvern T
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444275 , vital:74212 , xlink:href="https://www.emerald.com/insight/content/doi/10.1108/JACPR-05-2017-0295/full/html"
- Description: – In April 2016, students at Rhodes University brought the institution to a standstill as they protested the University’s sexual violence policies and procedures, as well as the “rape culture” that pervades social structures. In response, a Sexual Violence Task Team (SVTT) was formed in an open, participatory, and transparent process. Members of the University community were invited to comment on drafts of the SVTT document. The purpose of this paper is to outline the contestations – arising from both the establishment of the task team and the inputs from University members to drafts of the document – that surfaced concerning managing sexual violence on campuses and sexual offences policies.
- Full Text:
- Date Issued: 2018
Core-modified rubyrins with phenanthrene-fused pyrrole rings
- Yuan, Xuemei, Li, Minzhi, Meng, Ting, Mack, John, Soy, Rodah, Nyokong, Tebello, Zhu, Weihua, Xu, Haijun, Liang, Xu
- Authors: Yuan, Xuemei , Li, Minzhi , Meng, Ting , Mack, John , Soy, Rodah , Nyokong, Tebello , Zhu, Weihua , Xu, Haijun , Liang, Xu
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234568 , vital:50209 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.05.045"
- Description: Three fused-ring-expanded rubyrins with modified macrocyclic core have been synthesized and characterized. A series of spectroscopic, electrochemical measurements and a set of theoretical calculations demonstrate that the core-modification of the inner core of rubyrins has a large influence on the electronic structure. Colorimetric changes are observe that demonstrate that these core-modified rubyrins could be used as selective Hg2+ ion sensors. These properties can be fine-tuned by introducing lipophilic substituents on the meso-aryl rings.
- Full Text:
- Date Issued: 2018
- Authors: Yuan, Xuemei , Li, Minzhi , Meng, Ting , Mack, John , Soy, Rodah , Nyokong, Tebello , Zhu, Weihua , Xu, Haijun , Liang, Xu
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234568 , vital:50209 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.05.045"
- Description: Three fused-ring-expanded rubyrins with modified macrocyclic core have been synthesized and characterized. A series of spectroscopic, electrochemical measurements and a set of theoretical calculations demonstrate that the core-modification of the inner core of rubyrins has a large influence on the electronic structure. Colorimetric changes are observe that demonstrate that these core-modified rubyrins could be used as selective Hg2+ ion sensors. These properties can be fine-tuned by introducing lipophilic substituents on the meso-aryl rings.
- Full Text:
- Date Issued: 2018
Cropland abandonment in South African smallholder communal lands: Land cover change (1950–2010) and farmer perceptions of contributing factors
- Blair, Dale, Shackleton, Charlie M, Mograbi, Penelope J
- Authors: Blair, Dale , Shackleton, Charlie M , Mograbi, Penelope J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180297 , vital:43351 , xlink:href="https://doi.org/10.3390/land7040121"
- Description: Despite agricultural land abandonment threatening the food security and the livelihoods of smallholder farmers, it is pervasive globally and in developing countries. Yet land abandonment is an understudied aspect of land use change in social–ecological systems. Here we provide more information on this phenomenon by exploring cropland abandonment during 1950–2010 in four former South African ‘homelands’—part of the ‘Apartheid’ era racially-based land allocation programs—characterized by rural, smallholder farmers. Cropland abandonment 1950–2010 was widespread in all surveyed sites (KwaZulu: 0.08% year−1, Transkei: 0.13% year−1, Lebowa: 0.23% year−1, Venda: 0.28% year−1), with rates peaking between 1970 and 1990, with concomitant increases (up to 0.16% year−1) of woody vegetation cover at the expense of grassland cover. Active and past farmers attributed cropland abandonment to a lack of draught power, rainfall variability and droughts, and a more modernized youth disinclined to living a marginal agrarian lifestyle. We discuss the potential social and ecological implications of abandoned croplands at the local and regional scales, as the deagrarianization trend is unlikely to abate considering the failure of current South African national agricultural incentives.
- Full Text:
- Date Issued: 2018
- Authors: Blair, Dale , Shackleton, Charlie M , Mograbi, Penelope J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180297 , vital:43351 , xlink:href="https://doi.org/10.3390/land7040121"
- Description: Despite agricultural land abandonment threatening the food security and the livelihoods of smallholder farmers, it is pervasive globally and in developing countries. Yet land abandonment is an understudied aspect of land use change in social–ecological systems. Here we provide more information on this phenomenon by exploring cropland abandonment during 1950–2010 in four former South African ‘homelands’—part of the ‘Apartheid’ era racially-based land allocation programs—characterized by rural, smallholder farmers. Cropland abandonment 1950–2010 was widespread in all surveyed sites (KwaZulu: 0.08% year−1, Transkei: 0.13% year−1, Lebowa: 0.23% year−1, Venda: 0.28% year−1), with rates peaking between 1970 and 1990, with concomitant increases (up to 0.16% year−1) of woody vegetation cover at the expense of grassland cover. Active and past farmers attributed cropland abandonment to a lack of draught power, rainfall variability and droughts, and a more modernized youth disinclined to living a marginal agrarian lifestyle. We discuss the potential social and ecological implications of abandoned croplands at the local and regional scales, as the deagrarianization trend is unlikely to abate considering the failure of current South African national agricultural incentives.
- Full Text:
- Date Issued: 2018
Cultural De-colonization versus Liberal approaches to abortion in Africa: The politics of representation and voice
- Chiweshe, Malvern T, Macleod, Catriona I
- Authors: Chiweshe, Malvern T , Macleod, Catriona I
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443661 , vital:74142 , xlink:href="DOI/Handle/URL https://www.ajol.info/index.php/ajrh/article/view/175092"
- Description: Political discussions on abortion in Africa take place in the context of most countries having restrictive abortion legislation and high levels of unsafe abortion. In this paper two major political positions regarding abortion in Africa: a de-colonisation approach based on a homogenized view of ―culture‖, and a liberal approach based on ―choice‖ and rights are outlined. Using the Questions and Answers sessions of a United Nations event on maternal health in Africa as an exemplar of these positions, the paper argues that neither approach is emancipatory in the African context. A de-colonisation approach that uses static and homogenized understanding of ''culture'' risks engaging in a politics of representation that potentially silences the ―Other‖ (in this case women who terminate their pregnancies) and glosses over complexities and multiple power relations that exist on the continent. A liberal approach, premised on choice and reproductive rights, risks foregrounding individual women‘s agency at the expense of contextual dynamics, including the conditions that create unsupportable pregnancies. The paper argues for a grounded reproductive justice perspective that draws on the insights of the reproductive justice movement, but grounds these notions within the African philosophy of Hunhu/Ubuntu.
- Full Text:
- Date Issued: 2018
- Authors: Chiweshe, Malvern T , Macleod, Catriona I
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443661 , vital:74142 , xlink:href="DOI/Handle/URL https://www.ajol.info/index.php/ajrh/article/view/175092"
- Description: Political discussions on abortion in Africa take place in the context of most countries having restrictive abortion legislation and high levels of unsafe abortion. In this paper two major political positions regarding abortion in Africa: a de-colonisation approach based on a homogenized view of ―culture‖, and a liberal approach based on ―choice‖ and rights are outlined. Using the Questions and Answers sessions of a United Nations event on maternal health in Africa as an exemplar of these positions, the paper argues that neither approach is emancipatory in the African context. A de-colonisation approach that uses static and homogenized understanding of ''culture'' risks engaging in a politics of representation that potentially silences the ―Other‖ (in this case women who terminate their pregnancies) and glosses over complexities and multiple power relations that exist on the continent. A liberal approach, premised on choice and reproductive rights, risks foregrounding individual women‘s agency at the expense of contextual dynamics, including the conditions that create unsupportable pregnancies. The paper argues for a grounded reproductive justice perspective that draws on the insights of the reproductive justice movement, but grounds these notions within the African philosophy of Hunhu/Ubuntu.
- Full Text:
- Date Issued: 2018
Developing an electromagnetic noise generator to protect a Raspberry Pi from side channel analysis
- Frieslaar, I, Irwin, Barry V W
- Authors: Frieslaar, I , Irwin, Barry V W
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429511 , vital:72618 , https://ieeexplore.ieee.org/abstract/document/8531950
- Description: This research investigates the Electromagnetic (EM) side channel leakage of a Raspberry Pi 2 B+. An evaluation is performed on the EM leakage as the device executes the AES-128 cryptographic algorithm contained in the libcrypto++ library in a threaded environment. Four multi-threaded implementations are evaluated. These implementations are Portable Operating System Interface Threads, C++11 threads, Threading Building Blocks, and OpenMP threads. It is demonstrated that the various thread techniques have distinct variations in frequency and shape as EM emanations are leaked from the Raspberry Pi. It is demonstrated that the AES-128 cryptographic implementation within the libcrypto++ library on a Raspberry Pi is vulnerable to Side Channel Analysis (SCA) attacks. The cryptographic process was seen visibly within the EM spectrum and the data for this process was extracted where digital filtering techniques was applied to the signal. The resultant data was utilised in the Differential Electromagnetic Analysis (DEMA) attack and the results revealed 16 sub-keys that are required to recover the full AES-128 secret key. Based on this discovery, this research introduced a multi-threading approach with the utilisation of Secure Hash Algorithm (SHA) to serve as a software based countermeasure to mitigate SCA attacks. The proposed countermeasure known as the FRIES noise generator executed as a Daemon and generated EM noise that was able to hide the cryptographic implementations and prevent the DEMA attack and other statistical analysis.
- Full Text:
- Date Issued: 2018
- Authors: Frieslaar, I , Irwin, Barry V W
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429511 , vital:72618 , https://ieeexplore.ieee.org/abstract/document/8531950
- Description: This research investigates the Electromagnetic (EM) side channel leakage of a Raspberry Pi 2 B+. An evaluation is performed on the EM leakage as the device executes the AES-128 cryptographic algorithm contained in the libcrypto++ library in a threaded environment. Four multi-threaded implementations are evaluated. These implementations are Portable Operating System Interface Threads, C++11 threads, Threading Building Blocks, and OpenMP threads. It is demonstrated that the various thread techniques have distinct variations in frequency and shape as EM emanations are leaked from the Raspberry Pi. It is demonstrated that the AES-128 cryptographic implementation within the libcrypto++ library on a Raspberry Pi is vulnerable to Side Channel Analysis (SCA) attacks. The cryptographic process was seen visibly within the EM spectrum and the data for this process was extracted where digital filtering techniques was applied to the signal. The resultant data was utilised in the Differential Electromagnetic Analysis (DEMA) attack and the results revealed 16 sub-keys that are required to recover the full AES-128 secret key. Based on this discovery, this research introduced a multi-threading approach with the utilisation of Secure Hash Algorithm (SHA) to serve as a software based countermeasure to mitigate SCA attacks. The proposed countermeasure known as the FRIES noise generator executed as a Daemon and generated EM noise that was able to hide the cryptographic implementations and prevent the DEMA attack and other statistical analysis.
- Full Text:
- Date Issued: 2018
Development of a Postharvest Cold Treatment for Cryptophlebia peltastica (Lepidoptera: Tortricidae) for Export of Litchis From South Africa
- Moore, Sean D, Kirkman, Wayne, Peyper, Mellissa, Thackeray, Sean R, Marsberg, Tamryn, Albertyn, Sonnica, Hill, Martin P
- Authors: Moore, Sean D , Kirkman, Wayne , Peyper, Mellissa , Thackeray, Sean R , Marsberg, Tamryn , Albertyn, Sonnica , Hill, Martin P
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423729 , vital:72089 , xlink:href="https://doi.org/10.1093/jee/toy287"
- Description: The litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae), is endemic to sub-Saharan Africa and certain Indian Ocean islands. It is an important pest of litchis and to a lesser extent macadamias. Litchis are exported to certain markets that consider C. peltastica as a phytosanitary pest. Consequently, an effective postharvest phytosanitary treatment is required. This study sought to develop a cold disinfestation treatment for this purpose. First, it was established that the fifth instar was the most cold-tolerant larval stage, as it was the only instar for which there was still some survival after 12 d at 1°C. It was then determined that cold treatment trials could be conducted in artificial diet, as there was no survival of fifth instar C. peltastica in litchis after only 9 d at 1°C, whereas it took 15 d at this temperature before no survival of fifth instar C. peltastica was recorded in artificial diet. Consequently, cold susceptibility of fifth instar C. peltastica and the most cold-tolerant larval stages (fourth and fifth instar) of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), were compared in artificial diet. There was no survival of C. peltastica after 13 d at 1°C, whereas this was only so for T. leucotreta after 16 d. Consequently, it can be concluded that any cold treatment that has been proven effective against T. leucotreta would be as effective against C. peltastica. Finally, it was confirmed that the cold susceptibility of T. leucotreta in artificial diet did not overestimate the effect of cold on T. leucotreta larvae in litchis.
- Full Text:
- Date Issued: 2018
- Authors: Moore, Sean D , Kirkman, Wayne , Peyper, Mellissa , Thackeray, Sean R , Marsberg, Tamryn , Albertyn, Sonnica , Hill, Martin P
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423729 , vital:72089 , xlink:href="https://doi.org/10.1093/jee/toy287"
- Description: The litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae), is endemic to sub-Saharan Africa and certain Indian Ocean islands. It is an important pest of litchis and to a lesser extent macadamias. Litchis are exported to certain markets that consider C. peltastica as a phytosanitary pest. Consequently, an effective postharvest phytosanitary treatment is required. This study sought to develop a cold disinfestation treatment for this purpose. First, it was established that the fifth instar was the most cold-tolerant larval stage, as it was the only instar for which there was still some survival after 12 d at 1°C. It was then determined that cold treatment trials could be conducted in artificial diet, as there was no survival of fifth instar C. peltastica in litchis after only 9 d at 1°C, whereas it took 15 d at this temperature before no survival of fifth instar C. peltastica was recorded in artificial diet. Consequently, cold susceptibility of fifth instar C. peltastica and the most cold-tolerant larval stages (fourth and fifth instar) of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), were compared in artificial diet. There was no survival of C. peltastica after 13 d at 1°C, whereas this was only so for T. leucotreta after 16 d. Consequently, it can be concluded that any cold treatment that has been proven effective against T. leucotreta would be as effective against C. peltastica. Finally, it was confirmed that the cold susceptibility of T. leucotreta in artificial diet did not overestimate the effect of cold on T. leucotreta larvae in litchis.
- Full Text:
- Date Issued: 2018
Digital Inclusion: A model for e-Infrastructure and e-Services in Developing Countries
- Terzoli, Alfredo, Siebörger, Ingrid, Tsietsi, Mosiuoa, Gumbo, Sibukelo
- Authors: Terzoli, Alfredo , Siebörger, Ingrid , Tsietsi, Mosiuoa , Gumbo, Sibukelo
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430973 , vital:72733 , https://doi.org/10.1007/978-3-319-98827-6_7
- Description: A large portion of the South African population is still not connected in a productive manner to the Internet, despite the existence of a govern-ment plan for public broadband, ‘SA Connect’. One reason for this could be the lack of an appropriate model, through which connectivity can be diffused in a meaningful way through all areas of South Africa. This paper presents the model developed over more than a decade of experimentation in real life settings in the Siyakhula Living Lab, a joint venture between the universities of Rhodes and Fort Hare, South Afri-ca. The model proposes the ‘Broadband Island’ as basic e-infrastructure unit, which clusters nearby points-of-presence hosted in schools. In each Broadband Island is located an applications integra-tion platform, TeleWeaver, which monetizes channels of access to the local community, to support the e-infrastructure while providing useful services to the population and the Government.
- Full Text:
- Date Issued: 2018
- Authors: Terzoli, Alfredo , Siebörger, Ingrid , Tsietsi, Mosiuoa , Gumbo, Sibukelo
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430973 , vital:72733 , https://doi.org/10.1007/978-3-319-98827-6_7
- Description: A large portion of the South African population is still not connected in a productive manner to the Internet, despite the existence of a govern-ment plan for public broadband, ‘SA Connect’. One reason for this could be the lack of an appropriate model, through which connectivity can be diffused in a meaningful way through all areas of South Africa. This paper presents the model developed over more than a decade of experimentation in real life settings in the Siyakhula Living Lab, a joint venture between the universities of Rhodes and Fort Hare, South Afri-ca. The model proposes the ‘Broadband Island’ as basic e-infrastructure unit, which clusters nearby points-of-presence hosted in schools. In each Broadband Island is located an applications integra-tion platform, TeleWeaver, which monetizes channels of access to the local community, to support the e-infrastructure while providing useful services to the population and the Government.
- Full Text:
- Date Issued: 2018
Effect of doping vs covalent linking of a low symmetry zinc phthalocyanine to silica nanoparticles on singlet oxygen production
- Peteni, Siwaphiwe, Nyokong, Tebello
- Authors: Peteni, Siwaphiwe , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187873 , vital:44705 , xlink:href="https://doi.org/10.1016/j.ica.2018.06.029"
- Description: Tris[(4-(pyridin-4-ylthio)-2-thio-4-methylthiazol-5-yl)acetic acid phthalocyaninato] zinc (II) (3) was covalently linked to and doped onto SiNPs. An increase in triplet quantum yields for 3-SiNPs (linked) with decreasing lifetimes was observed. For 3-SiNPs (doped) there was a decrease in both the triplet quantum yield and lifetimes when compared to 3 alone. There was an increase in singlet oxygen quantum yields for 3-SiNPs (linked) compared to 3 from 0.67 to 0.80, while there was a decrease for 3-SiNPs (doped) to 0.25.
- Full Text:
- Date Issued: 2018
- Authors: Peteni, Siwaphiwe , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187873 , vital:44705 , xlink:href="https://doi.org/10.1016/j.ica.2018.06.029"
- Description: Tris[(4-(pyridin-4-ylthio)-2-thio-4-methylthiazol-5-yl)acetic acid phthalocyaninato] zinc (II) (3) was covalently linked to and doped onto SiNPs. An increase in triplet quantum yields for 3-SiNPs (linked) with decreasing lifetimes was observed. For 3-SiNPs (doped) there was a decrease in both the triplet quantum yield and lifetimes when compared to 3 alone. There was an increase in singlet oxygen quantum yields for 3-SiNPs (linked) compared to 3 from 0.67 to 0.80, while there was a decrease for 3-SiNPs (doped) to 0.25.
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- Date Issued: 2018