Incipient genetic isolation of a temperate migratory coastal sciaenid fish (Argyrosomus inodorus) within the Benguela Cold Current system
- Henriques, Romina, Potts, Warren M, Sauer, Warwick H H, Shaw, Paul W
- Authors: Henriques, Romina , Potts, Warren M , Sauer, Warwick H H , Shaw, Paul W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124710 , vital:35652 , https://doi.10.1080/17451000.2014.952309
- Description: The Benguela Cold Current system, located in the south-eastern Atlantic, features cold sea surface temperatures, bounded to the north and south by tropical currents (the Angola and Agulhas Currents, respectively) and a perennial upwelling cell off central Namibia that divides the region into two sub-systems with different characteristics (Shannon 1985; Hutchings et al. 2009). The colder sea surface temperatures of the Benguela Current have been considered an important biogeographic barrier, isolating tropical and warm-temperate fauna of the Atlantic and Indo-Pacific Oceans (Avise 2000; Floeter et al. 2008). However, recent studies revealed that other oceanographic features, such as the perennial upwelling cell, may also play an important role in shaping the population structure of warm temperate fish populations within the Benguela system, as complete disruption of gene flow was documented both in Lichia amia (Linnaeus, 1758) and Atractoscion aequidens (Cuvier, 1830) (Henriques et al. 2012, 2014). Little is known, however, regarding the influence of the Benguela system on genetic population connectivity of cold-water-tolerant species.
- Full Text:
- Date Issued: 2015
- Authors: Henriques, Romina , Potts, Warren M , Sauer, Warwick H H , Shaw, Paul W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124710 , vital:35652 , https://doi.10.1080/17451000.2014.952309
- Description: The Benguela Cold Current system, located in the south-eastern Atlantic, features cold sea surface temperatures, bounded to the north and south by tropical currents (the Angola and Agulhas Currents, respectively) and a perennial upwelling cell off central Namibia that divides the region into two sub-systems with different characteristics (Shannon 1985; Hutchings et al. 2009). The colder sea surface temperatures of the Benguela Current have been considered an important biogeographic barrier, isolating tropical and warm-temperate fauna of the Atlantic and Indo-Pacific Oceans (Avise 2000; Floeter et al. 2008). However, recent studies revealed that other oceanographic features, such as the perennial upwelling cell, may also play an important role in shaping the population structure of warm temperate fish populations within the Benguela system, as complete disruption of gene flow was documented both in Lichia amia (Linnaeus, 1758) and Atractoscion aequidens (Cuvier, 1830) (Henriques et al. 2012, 2014). Little is known, however, regarding the influence of the Benguela system on genetic population connectivity of cold-water-tolerant species.
- Full Text:
- Date Issued: 2015
A response to the South African Jewish report and Ms Klazinga on "Jews unwelcome at Rhodes"
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: text
- Identifier: vital:7883 , http://hdl.handle.net/10962/d1016432
- Description: On 1 January 2014, the South African Jewish Report and Ms Larissa Klazinga made a number of unfounded claims and unsubstantiated allegations against Rhodes University. Stripped of the hysteria, lies and inaccuracies, the central claim made is that Rhodes University is hostile to Jews and seeks to be rid of Jews. We reject with contempt these baseless and self-serving claims and allegations of the South African Jewish Report and Klazinga. Rhodes is committed to an institutional culture that respects and promotes equity, human dignity and human rights, embraces difference and diversity and is comfortable for all people irrespective of ‘race’, gender, language, culture, nationality, sexual orientation and religion. Rhodes welcomes all and will continue to strive to be a Home for All.
- Full Text:
- Date Issued: 2014
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: text
- Identifier: vital:7883 , http://hdl.handle.net/10962/d1016432
- Description: On 1 January 2014, the South African Jewish Report and Ms Larissa Klazinga made a number of unfounded claims and unsubstantiated allegations against Rhodes University. Stripped of the hysteria, lies and inaccuracies, the central claim made is that Rhodes University is hostile to Jews and seeks to be rid of Jews. We reject with contempt these baseless and self-serving claims and allegations of the South African Jewish Report and Klazinga. Rhodes is committed to an institutional culture that respects and promotes equity, human dignity and human rights, embraces difference and diversity and is comfortable for all people irrespective of ‘race’, gender, language, culture, nationality, sexual orientation and religion. Rhodes welcomes all and will continue to strive to be a Home for All.
- Full Text:
- Date Issued: 2014
A temporal dimension to the influence of pollen rewards on bee behaviour and fecundity in Aloe tenuior
- Duffy, Karl J, Johnson, Steven D, Peter, Craig I
- Authors: Duffy, Karl J , Johnson, Steven D , Peter, Craig I
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6561 , http://hdl.handle.net/10962/d1011735 , http://dx.doi.org/10.1371/journal.pone.0094908
- Description: The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.
- Full Text:
- Date Issued: 2014
- Authors: Duffy, Karl J , Johnson, Steven D , Peter, Craig I
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6561 , http://hdl.handle.net/10962/d1011735 , http://dx.doi.org/10.1371/journal.pone.0094908
- Description: The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.
- Full Text:
- Date Issued: 2014
Academic development as enhancement: celebrating a decade of the TLC through the annual teaching week
- Jonas, N, Schekle, L, Toni, N
- Authors: Jonas, N , Schekle, L , Toni, N
- Date: 2014
- Language: English
- Type: Newsletter
- Identifier: vital:12226 , http://hdl.handle.net/10353/d1016144
- Description: Teaching and Learning Centre newsletter 2014 first edition
- Full Text: false
- Date Issued: 2014
- Authors: Jonas, N , Schekle, L , Toni, N
- Date: 2014
- Language: English
- Type: Newsletter
- Identifier: vital:12226 , http://hdl.handle.net/10353/d1016144
- Description: Teaching and Learning Centre newsletter 2014 first edition
- Full Text: false
- Date Issued: 2014
An Associative Shared Memory Approach to Audio Connection Management
- Eales, Andrew, Foss, Richard
- Authors: Eales, Andrew , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426841 , vital:72395 , https://www.aes.org/e-lib/browse.cfm?elib=17539
- Description: A distributed, associative memory that advertises audio streams and represents audio connections between networked audio devices is described. Characteristic features of a shared, associative memory are discussed, and three parameter-based models that represent audio signals and audio connections are introduced. Connection management is then discussed with reference to a distributed, associative memory environment. This environment allows changes made to audio connections to be automatically propagated to all networked devices, while also eliminating potential race conditions between connection requests. Additionally, connection management applications can be shared between different networked devices and controllers.
- Full Text:
- Date Issued: 2014
- Authors: Eales, Andrew , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426841 , vital:72395 , https://www.aes.org/e-lib/browse.cfm?elib=17539
- Description: A distributed, associative memory that advertises audio streams and represents audio connections between networked audio devices is described. Characteristic features of a shared, associative memory are discussed, and three parameter-based models that represent audio signals and audio connections are introduced. Connection management is then discussed with reference to a distributed, associative memory environment. This environment allows changes made to audio connections to be automatically propagated to all networked devices, while also eliminating potential race conditions between connection requests. Additionally, connection management applications can be shared between different networked devices and controllers.
- Full Text:
- Date Issued: 2014
Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
On the viability of pro-active automated PII breach detection: A South African case study
- Swart, Ignus, Irwin, Barry V W, Grobler, Marthie
- Authors: Swart, Ignus , Irwin, Barry V W , Grobler, Marthie
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430235 , vital:72676 , https://doi.org/10.1145/2664591.2664600
- Description: Various reasons exist why certain types of information is deemed personal both by legislation and society. While crimes such as identity theft and impersonation have always been in existence, the rise of the internet and social media has exacerbated the problem. South Africa has recently joined the growing ranks of countries passing legislation to ensure the privacy of certain types of data. As is the case with most implemented security enforcement systems, most appointed privacy regulators operate in a reactive way. While this is a completely acceptable method of operation, it is not the most efficient. Research has shown that most data leaks containing personal information remains available for more than a month on average before being detected and reported. Quite often the data is discovered by a third party who selects to notify the responsible organisation but can just as easily copy the data and make use of it. This paper will display the potential benefit a privacy regulator can expect to see by implementing pro-active detection of electronic personally identifiable information (PII). Adopting pro-active detection of PII exposed on public networks can potentially contribute to a significant reduction in exposure time. The results discussed in this paper were obtained by means of experimentation on a custom created PII detection system.
- Full Text:
- Date Issued: 2014
- Authors: Swart, Ignus , Irwin, Barry V W , Grobler, Marthie
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430235 , vital:72676 , https://doi.org/10.1145/2664591.2664600
- Description: Various reasons exist why certain types of information is deemed personal both by legislation and society. While crimes such as identity theft and impersonation have always been in existence, the rise of the internet and social media has exacerbated the problem. South Africa has recently joined the growing ranks of countries passing legislation to ensure the privacy of certain types of data. As is the case with most implemented security enforcement systems, most appointed privacy regulators operate in a reactive way. While this is a completely acceptable method of operation, it is not the most efficient. Research has shown that most data leaks containing personal information remains available for more than a month on average before being detected and reported. Quite often the data is discovered by a third party who selects to notify the responsible organisation but can just as easily copy the data and make use of it. This paper will display the potential benefit a privacy regulator can expect to see by implementing pro-active detection of electronic personally identifiable information (PII). Adopting pro-active detection of PII exposed on public networks can potentially contribute to a significant reduction in exposure time. The results discussed in this paper were obtained by means of experimentation on a custom created PII detection system.
- Full Text:
- Date Issued: 2014
Temporal and spatial variability in the abundance, biomass and distribution of Palaemon peringueyi (Decapoda: Crustacea) are influenced by biological but not physico-chemical factors in the permanently open Kariega Estuary, South Africa
- Nyalungu, Nonhlanhla P, Hodgson, Alan N, Froneman, P William, Dopolo, M, Masubelele, M
- Authors: Nyalungu, Nonhlanhla P , Hodgson, Alan N , Froneman, P William , Dopolo, M , Masubelele, M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68106 , vital:29200 , https://doi.org/10.2989/16085914.2014.960792
- Description: Publisher version , Biological and physico-chemical factors affecting abundance and biomass of shrimp Palaemon peringueyi were investigated in 2010–2011 in the lower, middle and upper reaches of the freshwater-deprived permanently open Kariega Estuary. Shrimp abundance and biomass ranged from 0 to 88 ind. m−2 and 0 to 4.4 g wwt m−2, respectively. Shrimps were most abundant in the lower reach, and highest abundances and biomasses were recorded in the lower reach in June when salinities were low. The shrimps were almost always absent in the upper reach. Juveniles were found mostly in the lower and middle reaches, whereas adults were distributed in all three reaches. Regression analyses showed no statistically significant relationship for either abundance or biomass of the shrimps with temperature, salinity and dissolved oxygen (p > 0.05). The relationship between shrimp abundance and biomass and vegetation cover was positive and statistically significant (R2 = 0.109 and 0.185, respectively; p < 0.05). Vegetation cover plays an important role in determining the presence, distribution and abundance or biomass of P. peringueyi in this estuary.
- Full Text: false
- Date Issued: 2014
- Authors: Nyalungu, Nonhlanhla P , Hodgson, Alan N , Froneman, P William , Dopolo, M , Masubelele, M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68106 , vital:29200 , https://doi.org/10.2989/16085914.2014.960792
- Description: Publisher version , Biological and physico-chemical factors affecting abundance and biomass of shrimp Palaemon peringueyi were investigated in 2010–2011 in the lower, middle and upper reaches of the freshwater-deprived permanently open Kariega Estuary. Shrimp abundance and biomass ranged from 0 to 88 ind. m−2 and 0 to 4.4 g wwt m−2, respectively. Shrimps were most abundant in the lower reach, and highest abundances and biomasses were recorded in the lower reach in June when salinities were low. The shrimps were almost always absent in the upper reach. Juveniles were found mostly in the lower and middle reaches, whereas adults were distributed in all three reaches. Regression analyses showed no statistically significant relationship for either abundance or biomass of the shrimps with temperature, salinity and dissolved oxygen (p > 0.05). The relationship between shrimp abundance and biomass and vegetation cover was positive and statistically significant (R2 = 0.109 and 0.185, respectively; p < 0.05). Vegetation cover plays an important role in determining the presence, distribution and abundance or biomass of P. peringueyi in this estuary.
- Full Text: false
- Date Issued: 2014
Towards a Sandbox for the Deobfuscation and Dissection of PHP Malware
- Wrench, Peter M, Irwin, Barry V W
- Authors: Wrench, Peter M , Irwin, Barry V W
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429700 , vital:72633 , 10.1109/ISSA.2014.6950504
- Description: The creation and proliferation of PHP-based Remote Access Trojans (or web shells) used in both the compromise and post exploitation of web platforms has fuelled research into automated methods of dissecting and analysing these shells. Current malware tools disguise themselves by making use of obfuscation techniques designed to frustrate any efforts to dissect or reverse engineer the code. Advanced code engineering can even cause malware to behave differently if it detects that it is not running on the system for which it was originally targeted. To combat these defensive techniques, this paper presents a sandbox-based environment that aims to accurately mimic a vulnerable host and is capable of semi-automatic semantic dissection and syntactic deobfuscation of PHP code.
- Full Text:
- Date Issued: 2014
- Authors: Wrench, Peter M , Irwin, Barry V W
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429700 , vital:72633 , 10.1109/ISSA.2014.6950504
- Description: The creation and proliferation of PHP-based Remote Access Trojans (or web shells) used in both the compromise and post exploitation of web platforms has fuelled research into automated methods of dissecting and analysing these shells. Current malware tools disguise themselves by making use of obfuscation techniques designed to frustrate any efforts to dissect or reverse engineer the code. Advanced code engineering can even cause malware to behave differently if it detects that it is not running on the system for which it was originally targeted. To combat these defensive techniques, this paper presents a sandbox-based environment that aims to accurately mimic a vulnerable host and is capable of semi-automatic semantic dissection and syntactic deobfuscation of PHP code.
- Full Text:
- Date Issued: 2014
Towards building an indigenous knowledge platform to enable culturally-sensitive education underpinned by technological pedagogical and content knowledge (TPACK)
- Ntšekhe, Mathe, Terzoli, Alfredo, Thinyane, Mamello
- Authors: Ntšekhe, Mathe , Terzoli, Alfredo , Thinyane, Mamello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431424 , vital:72773 , http://proceedings.e-skillsconference.org/2014/e-skills275-284Ntsekhe821.pdf
- Description: The everyday use of Information and Communication Technologies (ICTs) is ingrained to the fabric of today’s society. A question open for debate is whether this use is or can be optimized to engender authentic solutions, which are aligned to the natural environment of the people? In this paper, we examine at the question from the vantage point of ed-ucating the rural African child. We engage with the sub-question: can ICTs facilitate education grounded in people's own realities, especially those of the marginalized rural poor? We believe this is possible under specific conditions, which include making Indigenous Knowledge (IK) readily available. We propose building an ICT platform that allows injec-tion of IK into the education process: develop a solution that valorizes IK, but also supports efforts to use ICTs in education driven by Tech-nology, Pedagogy, and Content Knowledge (TPACK) framework. The main goal of this framework is to facilitate effective teaching with tech-nology. TPACK partially embeds IK within pedagogical knowledge and ‘contexts’ of learning; we argue for explicit inclusion of IK within the framework to complement the other knowledges.
- Full Text:
- Date Issued: 2014
- Authors: Ntšekhe, Mathe , Terzoli, Alfredo , Thinyane, Mamello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431424 , vital:72773 , http://proceedings.e-skillsconference.org/2014/e-skills275-284Ntsekhe821.pdf
- Description: The everyday use of Information and Communication Technologies (ICTs) is ingrained to the fabric of today’s society. A question open for debate is whether this use is or can be optimized to engender authentic solutions, which are aligned to the natural environment of the people? In this paper, we examine at the question from the vantage point of ed-ucating the rural African child. We engage with the sub-question: can ICTs facilitate education grounded in people's own realities, especially those of the marginalized rural poor? We believe this is possible under specific conditions, which include making Indigenous Knowledge (IK) readily available. We propose building an ICT platform that allows injec-tion of IK into the education process: develop a solution that valorizes IK, but also supports efforts to use ICTs in education driven by Tech-nology, Pedagogy, and Content Knowledge (TPACK) framework. The main goal of this framework is to facilitate effective teaching with tech-nology. TPACK partially embeds IK within pedagogical knowledge and ‘contexts’ of learning; we argue for explicit inclusion of IK within the framework to complement the other knowledges.
- Full Text:
- Date Issued: 2014
Tufa stromatolite ecosystems on the South African south coast
- Perissonotto, Renzo, Bornman, Tommy G, Steyn, Paul-Pierre, Miranda, Nelson A F, Dorrington, Rosemary A, Matcher, Gwynneth F, Strydom, Nadine A, Peer, Nasreen
- Authors: Perissonotto, Renzo , Bornman, Tommy G , Steyn, Paul-Pierre , Miranda, Nelson A F , Dorrington, Rosemary A , Matcher, Gwynneth F , Strydom, Nadine A , Peer, Nasreen
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6490 , http://hdl.handle.net/10962/d1014585 , http://dx.doi.org/10.1590/sajs.2014/20140011
- Description: Following the first description of living marine stromatolites along the South African east coast, new investigations along the south coast have revealed the occurrence of extensive fields of actively calcifying stromatolites. These stromatolites have been recorded at regular distances along a 200-km stretch of coastline, from Cape Recife in the east to the Storms River mouth in the west, with the highest density found between Schoenmakerskop and the Maitland River mouth. All active stromatolites are associated with freshwater seepage streams flowing from the dune cordon, which form rimstone dams and other accretions capable of retaining water in the supratidal platform. Resulting pools can reach a maximum depth of about 1 m and constitute a unique ecosystem in which freshwater and marine organisms alternate their dominance in response to vertical mixing and the balance between freshwater versus marine inflow. Although the factors controlling stromatolite growth are yet to be determined, nitrogen appears to be supplied mainly via the dune seeps. The epibenthic algal community within stromatolite pools is generally co-dominated by cyanobacteria and chlorophytes, with minimal diatom contribution.
- Full Text:
- Date Issued: 2014
- Authors: Perissonotto, Renzo , Bornman, Tommy G , Steyn, Paul-Pierre , Miranda, Nelson A F , Dorrington, Rosemary A , Matcher, Gwynneth F , Strydom, Nadine A , Peer, Nasreen
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6490 , http://hdl.handle.net/10962/d1014585 , http://dx.doi.org/10.1590/sajs.2014/20140011
- Description: Following the first description of living marine stromatolites along the South African east coast, new investigations along the south coast have revealed the occurrence of extensive fields of actively calcifying stromatolites. These stromatolites have been recorded at regular distances along a 200-km stretch of coastline, from Cape Recife in the east to the Storms River mouth in the west, with the highest density found between Schoenmakerskop and the Maitland River mouth. All active stromatolites are associated with freshwater seepage streams flowing from the dune cordon, which form rimstone dams and other accretions capable of retaining water in the supratidal platform. Resulting pools can reach a maximum depth of about 1 m and constitute a unique ecosystem in which freshwater and marine organisms alternate their dominance in response to vertical mixing and the balance between freshwater versus marine inflow. Although the factors controlling stromatolite growth are yet to be determined, nitrogen appears to be supplied mainly via the dune seeps. The epibenthic algal community within stromatolite pools is generally co-dominated by cyanobacteria and chlorophytes, with minimal diatom contribution.
- Full Text:
- Date Issued: 2014
Using multivariate analysis and stable isotopes to assess the effects of substrate type on phytobenthos communities
- Dalu, Tatenda, Richoux, Nicole B, Froneman, P William
- Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68123 , vital:29201 , https://doi.org/10.5268/IW-4.4.719
- Description: Publisher version , For more than a century, artificial substrates have been employed in phytobenthos studies. In the present study, we compared the phytobenthos community structure in a field experiment over 3 seasons (summer, autumn, and winter) on 3 types of artificial substrates (brick, brown clay tiles, and grey clay tiles) and 3 natural substrates (macrophytes, rocks, and sediment) in a small, temperate system. A combination of multivariate analyses (cluster, multi-response permutation procedure, indicator species [IndVal], and canonical correspondence analysis [CCA]) and stable isotope analysis was used. We identified 96 total phytobenthos taxa. Artificial substrates resulted in different substrate communities, as shown by stable isotope analysis, cluster analysis, and a multi-response permutation procedure, with only those communities growing on grey tiles being similar to natural substrate communities. Overall, artificial substrates exhibited slightly higher species richness compared to natural substrates over the 3 seasons, although there were no significant differences (p> 0.05). Phytobenthos grown on brown tiles, rocks, and bricks showed seasonal variability of the carbon isotope δ13C values using one-way ANOVA (p< 0.05). Phytobenthos community structure did not show great seasonal variation; however, CCA identified water flow, conductivity, ammonium, phosphate, and water depth as important in structuring phytobenthos communities on different substrates. IndVal analysis showed that common phytobenthos taxa were not restricted to a single substrate, but preference was generally high for natural substrate, especially rocks, compared to artificial substrates. Substrate microhabitat type seems to influence the communities within the study areas.
- Full Text: false
- Date Issued: 2014
- Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68123 , vital:29201 , https://doi.org/10.5268/IW-4.4.719
- Description: Publisher version , For more than a century, artificial substrates have been employed in phytobenthos studies. In the present study, we compared the phytobenthos community structure in a field experiment over 3 seasons (summer, autumn, and winter) on 3 types of artificial substrates (brick, brown clay tiles, and grey clay tiles) and 3 natural substrates (macrophytes, rocks, and sediment) in a small, temperate system. A combination of multivariate analyses (cluster, multi-response permutation procedure, indicator species [IndVal], and canonical correspondence analysis [CCA]) and stable isotope analysis was used. We identified 96 total phytobenthos taxa. Artificial substrates resulted in different substrate communities, as shown by stable isotope analysis, cluster analysis, and a multi-response permutation procedure, with only those communities growing on grey tiles being similar to natural substrate communities. Overall, artificial substrates exhibited slightly higher species richness compared to natural substrates over the 3 seasons, although there were no significant differences (p> 0.05). Phytobenthos grown on brown tiles, rocks, and bricks showed seasonal variability of the carbon isotope δ13C values using one-way ANOVA (p< 0.05). Phytobenthos community structure did not show great seasonal variation; however, CCA identified water flow, conductivity, ammonium, phosphate, and water depth as important in structuring phytobenthos communities on different substrates. IndVal analysis showed that common phytobenthos taxa were not restricted to a single substrate, but preference was generally high for natural substrate, especially rocks, compared to artificial substrates. Substrate microhabitat type seems to influence the communities within the study areas.
- Full Text: false
- Date Issued: 2014
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
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