Age and growth of Cape stumpnose Rhabdosargus holubi (Pisces: Sparidae) in the Eastern Cape, South Africa
- Farthing, Matthew William, James, Nicola C, Potts, Warren M
- Authors: Farthing, Matthew William , James, Nicola C , Potts, Warren M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/122891 , vital:35365 , https://doi.org/10.2989/1814232X.2016.1156577
- Description: Rhabdosargus holubi (Steindachner, 1881) is a small (maximum size = 450 mm total length; Heemstra and Heemstra 2004) sparid that is distributed along the south-east coast of Africa from St Helena Bay, South Africa, to Maputo, Mozambique (Götz and Cowley 2013). Spawning occurs in the nearshore marine environment primarily during winter, specifically May–August in KwaZulu-Natal (KZN) (Wallace 1975) and July–February in the South-Eastern Cape (Whitfield 1998). Individuals reach 50% sexual maturity at approximately 150 mm standard length (SL) in the Eastern Cape (Whitfield 1998). The early life stages are transported by the south-westward-flowing Agulhas Current, and recruit as post-flexion larvae and early juveniles into estuaries during late winter and early summer (Blaber 1974). The warm temperatures and high nutrient levels in estuaries favour fast growth (Blaber 1973a), and fish spend their first year of life in these environments, migrating back out to sea after reaching approximately 120 mm SL. Some individuals remain trapped in closed estuaries, where they may reach sizes greater than 200 mm SL (James et al. 2007a). Rhabdosargus holubi is the dominant estuarine-dependent marine teleost species recorded in permanently open and temporarily open/closed estuaries in the warm-temperate region, which spans the south, south-east and east coast of South Africa (Harrison 2005). The species is also an important component of the linefishery in many SouthAfrican estuaries (10–15.6% by number) (Pradervand and Baird 2002), particularly in Eastern Cape estuaries (Cowley et al. 2003). These figures underestimate the presence of R. holubi, as most individuals making use of estuaries are young, feeding predominately on filamentous macroalgae and diatom flora, and are generally too small to be caught with hook and line (De Wet and Marais 1990). James et al. (2007b) showed that R. holubi made up 34–92% of the annual seine-net catch in the East Kleinemonde Estuary. Rhabdosargus holubi is also important in the KZN shorebased linefishery, representing 4.6% of the total landed catch (Dunlop and Mann 2012).
- Full Text:
- Date Issued: 2016
- Authors: Farthing, Matthew William , James, Nicola C , Potts, Warren M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/122891 , vital:35365 , https://doi.org/10.2989/1814232X.2016.1156577
- Description: Rhabdosargus holubi (Steindachner, 1881) is a small (maximum size = 450 mm total length; Heemstra and Heemstra 2004) sparid that is distributed along the south-east coast of Africa from St Helena Bay, South Africa, to Maputo, Mozambique (Götz and Cowley 2013). Spawning occurs in the nearshore marine environment primarily during winter, specifically May–August in KwaZulu-Natal (KZN) (Wallace 1975) and July–February in the South-Eastern Cape (Whitfield 1998). Individuals reach 50% sexual maturity at approximately 150 mm standard length (SL) in the Eastern Cape (Whitfield 1998). The early life stages are transported by the south-westward-flowing Agulhas Current, and recruit as post-flexion larvae and early juveniles into estuaries during late winter and early summer (Blaber 1974). The warm temperatures and high nutrient levels in estuaries favour fast growth (Blaber 1973a), and fish spend their first year of life in these environments, migrating back out to sea after reaching approximately 120 mm SL. Some individuals remain trapped in closed estuaries, where they may reach sizes greater than 200 mm SL (James et al. 2007a). Rhabdosargus holubi is the dominant estuarine-dependent marine teleost species recorded in permanently open and temporarily open/closed estuaries in the warm-temperate region, which spans the south, south-east and east coast of South Africa (Harrison 2005). The species is also an important component of the linefishery in many SouthAfrican estuaries (10–15.6% by number) (Pradervand and Baird 2002), particularly in Eastern Cape estuaries (Cowley et al. 2003). These figures underestimate the presence of R. holubi, as most individuals making use of estuaries are young, feeding predominately on filamentous macroalgae and diatom flora, and are generally too small to be caught with hook and line (De Wet and Marais 1990). James et al. (2007b) showed that R. holubi made up 34–92% of the annual seine-net catch in the East Kleinemonde Estuary. Rhabdosargus holubi is also important in the KZN shorebased linefishery, representing 4.6% of the total landed catch (Dunlop and Mann 2012).
- Full Text:
- Date Issued: 2016
Community care worker perceptions of their roles in tuberculosis care and their information needs:
- Okeyo, Ida L A, Dowse, Roslind
- Authors: Okeyo, Ida L A , Dowse, Roslind
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156596 , vital:40029 , DOI: 10.4102/hsag.v21i0.962
- Description: Community care workers (CCWs) inhabit a central role in the management of tuberculosis (TB) patients in South Africa. CCWs attend training courses, but training is not standardised at either the national or provincial level. To explore perceptions of CCWs of their role in TB care and TB information needs.
- Full Text:
- Date Issued: 2016
- Authors: Okeyo, Ida L A , Dowse, Roslind
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156596 , vital:40029 , DOI: 10.4102/hsag.v21i0.962
- Description: Community care workers (CCWs) inhabit a central role in the management of tuberculosis (TB) patients in South Africa. CCWs attend training courses, but training is not standardised at either the national or provincial level. To explore perceptions of CCWs of their role in TB care and TB information needs.
- Full Text:
- Date Issued: 2016
Disentangling the identities and distribution patterns of the introduced beachfleas Orchestia gammarellus and Platorchestia platensis (Crustacea: Amphipoda Talitridae) in South Africa
- Diemer, Natalie, Griffiths, Charles L, Hodgson, Alan N
- Authors: Diemer, Natalie , Griffiths, Charles L , Hodgson, Alan N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443163 , vital:74084 , https://doi.org/10.1080/15627020.2016.1268930
- Description: Two introduced beachfleas, Orchestia gammarellus and Platorchestia platensis, have been recorded from South Africa, but have been misidentified by some earlier researchers and, prior to this study, each was also known from just a few, scattered observations, such that their true distributions remained obscure. We illustrate both species to clarify the features that identify and distinguish them and determine their true distributions by re-examining historical samples and by collecting new material from estuaries and lagoons along the west and south coasts of South Africa. Adult males of O. gammarellus have slender antennae and characteristic expanded, flattened, oar-like distal segments on pereopod 7. Adult males of P. platensis have the peduncle of antenna 2 strongly swollen and have bulbous, but not flattened, distal segments on pereopod 7. Both species occur under wrack and other debris along the banks of estuaries and sheltered lagoons. Orchestia gammarellus is found only along the south-west coast, in the Berg River Estuary, Langebaan Lagoon and the Diep River Estuary. Previous records from Knysna were misidentifications of P. platensis. Platorchestia platensis is found at one west coast site, Langebaan Lagoon, but is widely distributed from Cape Point eastwards to at least Algoa Bay. Both species share the same habitats as several other native beachfleas and competitive interactions between native and introduced species merit investigation.
- Full Text:
- Date Issued: 2016
- Authors: Diemer, Natalie , Griffiths, Charles L , Hodgson, Alan N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443163 , vital:74084 , https://doi.org/10.1080/15627020.2016.1268930
- Description: Two introduced beachfleas, Orchestia gammarellus and Platorchestia platensis, have been recorded from South Africa, but have been misidentified by some earlier researchers and, prior to this study, each was also known from just a few, scattered observations, such that their true distributions remained obscure. We illustrate both species to clarify the features that identify and distinguish them and determine their true distributions by re-examining historical samples and by collecting new material from estuaries and lagoons along the west and south coasts of South Africa. Adult males of O. gammarellus have slender antennae and characteristic expanded, flattened, oar-like distal segments on pereopod 7. Adult males of P. platensis have the peduncle of antenna 2 strongly swollen and have bulbous, but not flattened, distal segments on pereopod 7. Both species occur under wrack and other debris along the banks of estuaries and sheltered lagoons. Orchestia gammarellus is found only along the south-west coast, in the Berg River Estuary, Langebaan Lagoon and the Diep River Estuary. Previous records from Knysna were misidentifications of P. platensis. Platorchestia platensis is found at one west coast site, Langebaan Lagoon, but is widely distributed from Cape Point eastwards to at least Algoa Bay. Both species share the same habitats as several other native beachfleas and competitive interactions between native and introduced species merit investigation.
- Full Text:
- Date Issued: 2016
Evaluating the multi-threading countermeasure
- Frieslaar, Ibrahim, Irwin, Barry V W
- Authors: Frieslaar, Ibrahim , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428352 , vital:72505 , https://researchspace.csir.co.za/dspace/bitstream/handle/10204/9041/Frieslaar_2016.pdf?sequence=1andisAllowed=y
- Description: This research investigates the resistance of the multi-threaded coun-termeasure to side channel analysis (SCA) attacks. The multi-threaded countermeasure is attacked using the Correlation Power Analysis (CPA) and template attacks. Additionally, it is compared to the existing hiding countermeasure. Furthermore, additional signal processing techniques are used to increase the attack success ratio. It is demon-strated that the multi-threaded countermeasure is able to outperform the existing countermeasures by withstanding the CPA and template at-tacks. Furthermore, the multi-threaded countermeasure is unaffected by the elastic alignment and filtering techniques as opposed to the existing countermeasures. The research concludes that the multithreaded coun-termeasure is indeed a secure implementation to mitigate SCA attacks.
- Full Text:
- Date Issued: 2016
- Authors: Frieslaar, Ibrahim , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428352 , vital:72505 , https://researchspace.csir.co.za/dspace/bitstream/handle/10204/9041/Frieslaar_2016.pdf?sequence=1andisAllowed=y
- Description: This research investigates the resistance of the multi-threaded coun-termeasure to side channel analysis (SCA) attacks. The multi-threaded countermeasure is attacked using the Correlation Power Analysis (CPA) and template attacks. Additionally, it is compared to the existing hiding countermeasure. Furthermore, additional signal processing techniques are used to increase the attack success ratio. It is demon-strated that the multi-threaded countermeasure is able to outperform the existing countermeasures by withstanding the CPA and template at-tacks. Furthermore, the multi-threaded countermeasure is unaffected by the elastic alignment and filtering techniques as opposed to the existing countermeasures. The research concludes that the multithreaded coun-termeasure is indeed a secure implementation to mitigate SCA attacks.
- Full Text:
- Date Issued: 2016
Macroinvertebrate communities associated with duckweed (Lemnaceae) in two Eastern Cape rivers, South Africa
- Muskett, Phillippa C, Hill, Jaclyn M, Weyl, Philip S R
- Authors: Muskett, Phillippa C , Hill, Jaclyn M , Weyl, Philip S R
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444065 , vital:74182 , https://doi.org/10.2989/16085914.2016.1241173
- Description: The functional feeding groups and diversity of macroinvertebrate communities associated with duckweed mats in the New Years River (two sites) and Bloukrans River (two sites), Eastern Cape province, South Africa, were assessed. Duckweed (Lemnaceae) is a ubiquitous family of floating macrophytes. A total of 41 macroinvertebrate families were collected monthly over a six-month period from February to July 2014. Duckweed biomass in both rivers was highly variable both temporally and spatially. The majority of identified macroinvertebrate taxa were predators and detritivores, with a small percentage of herbivores. An average of approximately 26% of the macroinvertebrate taxa found were from families that include species from more than one functional feeding group. Although overall measures of diversity and ecosystem health (Fisher’s α and Simpson’s index) remained constant over time in the New Years River, significant differences in macroinvertebrate community structure were seen between sites and months on both rivers, with dissimilarity being driven by a larger number of species in the New Years River. This high variability within macroinvertebrate assemblages probably reflects a combination of heterogeneous duckweed distribution, variation in physico-chemistry, opportunistic behaviours of macroinvertebrate predators and/or successional colonisation of duckweed mats.
- Full Text:
- Date Issued: 2016
- Authors: Muskett, Phillippa C , Hill, Jaclyn M , Weyl, Philip S R
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444065 , vital:74182 , https://doi.org/10.2989/16085914.2016.1241173
- Description: The functional feeding groups and diversity of macroinvertebrate communities associated with duckweed mats in the New Years River (two sites) and Bloukrans River (two sites), Eastern Cape province, South Africa, were assessed. Duckweed (Lemnaceae) is a ubiquitous family of floating macrophytes. A total of 41 macroinvertebrate families were collected monthly over a six-month period from February to July 2014. Duckweed biomass in both rivers was highly variable both temporally and spatially. The majority of identified macroinvertebrate taxa were predators and detritivores, with a small percentage of herbivores. An average of approximately 26% of the macroinvertebrate taxa found were from families that include species from more than one functional feeding group. Although overall measures of diversity and ecosystem health (Fisher’s α and Simpson’s index) remained constant over time in the New Years River, significant differences in macroinvertebrate community structure were seen between sites and months on both rivers, with dissimilarity being driven by a larger number of species in the New Years River. This high variability within macroinvertebrate assemblages probably reflects a combination of heterogeneous duckweed distribution, variation in physico-chemistry, opportunistic behaviours of macroinvertebrate predators and/or successional colonisation of duckweed mats.
- Full Text:
- Date Issued: 2016
Parallel visions: Byron, Géricault and the Medusa
- Authors: Beard, Margot
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147792 , vital:38673 , https://doi.org/10.1080/00043389.1999.11761285
- Description: Martin Meisel has noted that Delacroix's 1841 painting A Shipwreck was recognised as uniting Gericault and Byron. for not only does the painting illustrate that moment in Don Juan when lots are drawn for the human sacrifice {2, 75) but it also invokes comparison with Gericault' s 1819 painting entitled Raft of the Medusa(Meisel1988:601).1 would like to argue in this paper that Gericault' s famous painting and Byron's shipwreck stanzas in the second canto of Don Juan have other points of comparison. Gericault used the Savigny and Correard Narrative of a Voyage to Senegal ( 1817) as the primary source of information for his treatment of the Medusa incident (Eitner 1971: 117). Byron used multiple sources when he researched material for his shipwreck stanzas but it is highly probable that the Savigny and Correard text was one of them. Thus, the cause celebre of the wreck of the Medusa is directly treated by Gericault and indirectly by Byron - two artists temperamentally and artistically attuned.
- Full Text:
- Date Issued: 2016
- Authors: Beard, Margot
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147792 , vital:38673 , https://doi.org/10.1080/00043389.1999.11761285
- Description: Martin Meisel has noted that Delacroix's 1841 painting A Shipwreck was recognised as uniting Gericault and Byron. for not only does the painting illustrate that moment in Don Juan when lots are drawn for the human sacrifice {2, 75) but it also invokes comparison with Gericault' s 1819 painting entitled Raft of the Medusa(Meisel1988:601).1 would like to argue in this paper that Gericault' s famous painting and Byron's shipwreck stanzas in the second canto of Don Juan have other points of comparison. Gericault used the Savigny and Correard Narrative of a Voyage to Senegal ( 1817) as the primary source of information for his treatment of the Medusa incident (Eitner 1971: 117). Byron used multiple sources when he researched material for his shipwreck stanzas but it is highly probable that the Savigny and Correard text was one of them. Thus, the cause celebre of the wreck of the Medusa is directly treated by Gericault and indirectly by Byron - two artists temperamentally and artistically attuned.
- Full Text:
- Date Issued: 2016
Principles of Control Protocol Design and Implementation
- Eales, Andrew, Foss, Richard
- Authors: Eales, Andrew , Foss, Richard
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426801 , vital:72392 , https://www.aes.org/e-lib/online/browse.cfm?elib=18238
- Description: Control protocols are used within audio networks to manage both audio streams and networked audio devices. A number of control protocols for audio devices have been recently developed, including the AES standards AES64-2012 and AES70-2015. Despite these developments, an ontology of control protocol design and implementation does not exist. This paper proposes design and implementation heuristics for control protocols. Different categories of control protocol design and implementation heuristics are presented and the implications of individual heuristics are discussed. These heuristics allow the features provided by different control protocols to be compared and evaluated and provide guidelines for future control protocol development.
- Full Text:
- Date Issued: 2016
- Authors: Eales, Andrew , Foss, Richard
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426801 , vital:72392 , https://www.aes.org/e-lib/online/browse.cfm?elib=18238
- Description: Control protocols are used within audio networks to manage both audio streams and networked audio devices. A number of control protocols for audio devices have been recently developed, including the AES standards AES64-2012 and AES70-2015. Despite these developments, an ontology of control protocol design and implementation does not exist. This paper proposes design and implementation heuristics for control protocols. Different categories of control protocol design and implementation heuristics are presented and the implications of individual heuristics are discussed. These heuristics allow the features provided by different control protocols to be compared and evaluated and provide guidelines for future control protocol development.
- Full Text:
- Date Issued: 2016
Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars
- Pagonis, Vasilis, Ankjærgaard, Christina, Jain, Mayank, Chithambo, Makaiko L
- Authors: Pagonis, Vasilis , Ankjærgaard, Christina , Jain, Mayank , Chithambo, Makaiko L
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124616 , vital:35638 , DOI: 10.1016/j.physb.2016.06.013
- Description: Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IRSL signals, both during and after short infrared stimulation pulses. The equations are developed using a recently proposed kinetic model, which describes localized electronic recombination via tunneling between trapped electrons and recombination centers in luminescent materials. Recombination is assumed to take place from the excited state of the trapped electron to the nearest-neighbor center within a random distribution of luminescence recombination centers. Different possibilities are examined within the model, depending on the relative importance of electron de-excitation and recombination. The equations are applied to experimental TR-IRSL data of natural feldspars, and good agreement is found between experimental and modeling results.
- Full Text:
- Date Issued: 2016
- Authors: Pagonis, Vasilis , Ankjærgaard, Christina , Jain, Mayank , Chithambo, Makaiko L
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124616 , vital:35638 , DOI: 10.1016/j.physb.2016.06.013
- Description: Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IRSL signals, both during and after short infrared stimulation pulses. The equations are developed using a recently proposed kinetic model, which describes localized electronic recombination via tunneling between trapped electrons and recombination centers in luminescent materials. Recombination is assumed to take place from the excited state of the trapped electron to the nearest-neighbor center within a random distribution of luminescence recombination centers. Different possibilities are examined within the model, depending on the relative importance of electron de-excitation and recombination. The equations are applied to experimental TR-IRSL data of natural feldspars, and good agreement is found between experimental and modeling results.
- Full Text:
- Date Issued: 2016
Song analysis of South African pygmy bladder cicadas (Hemiptera: Cicadidae: Cicadettinae: Tettigomyiini).
- Sanborn, Allen F, Phillips, Polly K F, Villet, Martin H
- Authors: Sanborn, Allen F , Phillips, Polly K F , Villet, Martin H
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442319 , vital:73975 , https://doi.org/10.1093/aesa/saw024
- Description: The callings songs of five species from three genera of South African pygmy bladder cicadas are analyzed. The call of each species has a distinct temporal pattern and frequency spectrum. The songs are of significantly lower frequency than would be predicted based on body mass or body length. Comparison of bladder cicada calls from Australia and South Africa show similar lower than predicted frequencies in species of independent evolutionary origin. The inflated abdomen found in these cicadas appears to be a convergent adaptation to permit more efficient song production at lower carrier frequencies that increase the distance the songs will travel.
- Full Text:
- Date Issued: 2016
- Authors: Sanborn, Allen F , Phillips, Polly K F , Villet, Martin H
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442319 , vital:73975 , https://doi.org/10.1093/aesa/saw024
- Description: The callings songs of five species from three genera of South African pygmy bladder cicadas are analyzed. The call of each species has a distinct temporal pattern and frequency spectrum. The songs are of significantly lower frequency than would be predicted based on body mass or body length. Comparison of bladder cicada calls from Australia and South Africa show similar lower than predicted frequencies in species of independent evolutionary origin. The inflated abdomen found in these cicadas appears to be a convergent adaptation to permit more efficient song production at lower carrier frequencies that increase the distance the songs will travel.
- Full Text:
- Date Issued: 2016
Sperm ultrastructure and spermatodesm morphology of the spittle bug Locris transversa (Thunberg 1822)(Hemiptera: Cercopidae)
- Hodgson, Alan N, Ridgeway, Jaryd A, Villet, Martin H
- Authors: Hodgson, Alan N , Ridgeway, Jaryd A , Villet, Martin H
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442333 , vital:73976 , https://doi.org/10.1080/07924259.2016.1157104
- Description: The structure of the spermatozoon and spermatodesm of the spittlebug Locris transversa (Thunberg 1822) was investigated by light and transmission electron microscopy. Males produced only one size class of sperm, which was 93–106 μm long. During spermatogenesis groups of spermatozoa are arranged around, and attached by their acrosomes to, a small central extracellular matrix to form a ball-shaped spermatodesm. Spermatodesmata were found in the testis, vas deferens and seminal vesicle of males and spermatheca of females. The sperm are filiform, each consisting of a ~15-μm-long head containing an anteriorly positioned conical ~2-μm-long acrosome and ~13-μm-long nucleus, and a midpiece and tail with a 9+9+2 axoneme. The acrosome, which has two posterior extensions that lie along one side of the anterior region of the nucleus, contains longitudinally orientated microfilaments. The nucleus has two unequal anterior extensions, whereas posteriorly it is flattened laterally to accommodate a putative centriolar adjunct and anterior ends of the two mitochondrial derivatives. The basal body lies posterior to the nucleus. The mitochondrial derivatives are elongated and extend for almost the entire length of the tail. The tail has glycogen within its centre, and towards its terminal end large deposits of glycogen surround the mitochondrial derivatives and axoneme. Compared to other members of the Cicadomorpha, the spermatozoa and spermatodesms of cercopids so far studied have some structural features in common with cicadellids and others in common with cicadas; therefore, if sperm features are to be useful in phylogenetic studies of cicadomorphs, attention must be given to examining key taxa to establish which character states are plesiomorphic or apomorphic.
- Full Text:
- Date Issued: 2016
- Authors: Hodgson, Alan N , Ridgeway, Jaryd A , Villet, Martin H
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442333 , vital:73976 , https://doi.org/10.1080/07924259.2016.1157104
- Description: The structure of the spermatozoon and spermatodesm of the spittlebug Locris transversa (Thunberg 1822) was investigated by light and transmission electron microscopy. Males produced only one size class of sperm, which was 93–106 μm long. During spermatogenesis groups of spermatozoa are arranged around, and attached by their acrosomes to, a small central extracellular matrix to form a ball-shaped spermatodesm. Spermatodesmata were found in the testis, vas deferens and seminal vesicle of males and spermatheca of females. The sperm are filiform, each consisting of a ~15-μm-long head containing an anteriorly positioned conical ~2-μm-long acrosome and ~13-μm-long nucleus, and a midpiece and tail with a 9+9+2 axoneme. The acrosome, which has two posterior extensions that lie along one side of the anterior region of the nucleus, contains longitudinally orientated microfilaments. The nucleus has two unequal anterior extensions, whereas posteriorly it is flattened laterally to accommodate a putative centriolar adjunct and anterior ends of the two mitochondrial derivatives. The basal body lies posterior to the nucleus. The mitochondrial derivatives are elongated and extend for almost the entire length of the tail. The tail has glycogen within its centre, and towards its terminal end large deposits of glycogen surround the mitochondrial derivatives and axoneme. Compared to other members of the Cicadomorpha, the spermatozoa and spermatodesms of cercopids so far studied have some structural features in common with cicadellids and others in common with cicadas; therefore, if sperm features are to be useful in phylogenetic studies of cicadomorphs, attention must be given to examining key taxa to establish which character states are plesiomorphic or apomorphic.
- Full Text:
- Date Issued: 2016
The network society: A model for computing infrastructure in South African schools
- Siebörger, Ingrid, Terzoli, Alfredo
- Authors: Siebörger, Ingrid , Terzoli, Alfredo
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430651 , vital:72706 , 10.1109/ISTAFRICA.2016.7530673
- Description: Worldwide computers are being used in schools for, amongst other things, developing the knowledge and skills required for citizens to be able to operate within the 21st Century Information Age. Realising the potential of technology in uplifting the lives of its citizens the South Afri-can government has proposed the National Broadband Plan (SA Con-nect). However, unfortunately this plan only addresses the networking aspect of Information Communication Technologies (ICTs). In this pa-per we investigate appropriate Information Technologies for schools in the light of SA Connect, and propose a model for the computing infra-structure required in South African schools in order to support access to and adoption of technology and networks. This model is based on our multi-year experimentation in the Siyakhula Living Lab.
- Full Text:
- Date Issued: 2016
- Authors: Siebörger, Ingrid , Terzoli, Alfredo
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430651 , vital:72706 , 10.1109/ISTAFRICA.2016.7530673
- Description: Worldwide computers are being used in schools for, amongst other things, developing the knowledge and skills required for citizens to be able to operate within the 21st Century Information Age. Realising the potential of technology in uplifting the lives of its citizens the South Afri-can government has proposed the National Broadband Plan (SA Con-nect). However, unfortunately this plan only addresses the networking aspect of Information Communication Technologies (ICTs). In this pa-per we investigate appropriate Information Technologies for schools in the light of SA Connect, and propose a model for the computing infra-structure required in South African schools in order to support access to and adoption of technology and networks. This model is based on our multi-year experimentation in the Siyakhula Living Lab.
- Full Text:
- Date Issued: 2016
Utilizing gesture recognition and Ethernet AVB for distributed surround sound control
- Hedges, Mitchell, Foss, Richard
- Authors: Hedges, Mitchell , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426816 , vital:72393 , https://www.aes.org/e-lib/online/browse.cfm?elib=17540
- Description: Gesture recognition has become a preferred approach to the control of various systems. This allows users of the system to interact without having to use any controls or equipment. This paper investigates the use of gesture recognition in order to select and transport audio tracks over an Ethernet AVB network to speaker endpoints. The research uses equipment that is commercially available and relatively cost efficient. The endpoints receive audio samples that are encapsulated within network packets and processes them. The audio tracks are mixed at the endpoints according to gain ratios that will change and be different for each endpoint.
- Full Text:
- Date Issued: 2014
- Authors: Hedges, Mitchell , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426816 , vital:72393 , https://www.aes.org/e-lib/online/browse.cfm?elib=17540
- Description: Gesture recognition has become a preferred approach to the control of various systems. This allows users of the system to interact without having to use any controls or equipment. This paper investigates the use of gesture recognition in order to select and transport audio tracks over an Ethernet AVB network to speaker endpoints. The research uses equipment that is commercially available and relatively cost efficient. The endpoints receive audio samples that are encapsulated within network packets and processes them. The audio tracks are mixed at the endpoints according to gain ratios that will change and be different for each endpoint.
- Full Text:
- Date Issued: 2014
A Review of Arterial Stiffness and HIV Infection in Adult Africans
- Awotedu, Kofoworola Olajire, Iputo, Jehu
- Authors: Awotedu, Kofoworola Olajire , Iputo, Jehu
- Date: 09-06-2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3484 , vital:43615 , https://www.hilarispublisher.com/open-access/a-review-of-arterial-stiffness-and-hiv-infection-in-adult-africans-2167-1095-1000221.pdf
- Description: Aim: To review the impact of the human immunodeficiency virus and antiretroviral therapy on the vasculature. Objectives: This review seeks to identify the burden which the human immunodeficiency virus and antiretroviral therapy have on the vasculature. Method: Medline/PubMed and Google scholar were searched. There were over 100 publications reviewed. Some people who worked in similar fields were also contacted. The present review summarized current understanding of Human immunodeficiency virus, antiretroviral therapy and effect on the vasculature such as arterial stiffness. Atherosclerosis, endothelial dysfunction, the strengths and weaknesses of current testing strategies, and their potential applications in clinical research and patient care. The association of inflammatory biomarkers, blood pressure and ageing with arterial stiffness were also reviewed. Conclusion: Available literature shows that HIV and antiretroviral agents have a great impact on the vasculature and its progression.
- Full Text:
- Date Issued: 09-06-2016
- Authors: Awotedu, Kofoworola Olajire , Iputo, Jehu
- Date: 09-06-2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3484 , vital:43615 , https://www.hilarispublisher.com/open-access/a-review-of-arterial-stiffness-and-hiv-infection-in-adult-africans-2167-1095-1000221.pdf
- Description: Aim: To review the impact of the human immunodeficiency virus and antiretroviral therapy on the vasculature. Objectives: This review seeks to identify the burden which the human immunodeficiency virus and antiretroviral therapy have on the vasculature. Method: Medline/PubMed and Google scholar were searched. There were over 100 publications reviewed. Some people who worked in similar fields were also contacted. The present review summarized current understanding of Human immunodeficiency virus, antiretroviral therapy and effect on the vasculature such as arterial stiffness. Atherosclerosis, endothelial dysfunction, the strengths and weaknesses of current testing strategies, and their potential applications in clinical research and patient care. The association of inflammatory biomarkers, blood pressure and ageing with arterial stiffness were also reviewed. Conclusion: Available literature shows that HIV and antiretroviral agents have a great impact on the vasculature and its progression.
- Full Text:
- Date Issued: 09-06-2016
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