Inter-seasonal persistence and size-structuring of two minnow species within headwater streams in the Eastern Cape, South Africa
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124866 , vital:35705 , https://doi.10.1111/j.1439-0426.2012.02027.x
- Description: This study examined temporal variation in population dynamics and size structuring of two cyprinid minnows, Pseudobarbus afer and Barbus anoplus, in relation to their proximate physical habitats. Population estimates were determined using three-pass depletion sampling during both summer and winter. The habitats were characterised by seasonal variation in all physico-chemical conditions and spatial variation in substrata compositions. Whereas significant differences in population size were noted between seasons for B. anoplus, no differences were found between seasons for density and capture probability for either species. An increase in boulders was associated with increase in population size and density for P. afer; for B. anoplus, increased percentages of bedrock and bank vegetation were associated with an increase in population size and probability of capture, respectively. According to Canonical Correspondence Analysis, size structuring in P. afer was explained predominantly by seasonality, with smaller length classes associated with the seasonal variable of summer, while larger length classes were associated with pH that was higher in winter. By comparison, for B. anoplus, the habitat variables – bank vegetation and bedrock – accounted for much of the explained variance for size structuring. Recruitment appeared to be the major driver of size structuring for the two species; refugia, especially boulders and bank vegetation, also appeared to be important. Overall, the two species were adapted to the headwater streams that were generally variable in environmental conditions. Potential invasions by non-native invasive fishes that occur within the mainstream habitats threaten these two species. Efforts should continue to protect these minnows from such invasions by constructing barriers to upstream migration of non-native fishes into these headwater habitats.
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- Date Issued: 2012
The nature and quality of the mathematical connections teachers make:
- Authors: Mhlolo, Michael K , Schäfer, Marc , Venkat, Hamsa
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140893 , vital:37927 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC120887
- Description: Current reforms in mathematics education emphasise the need for pedagogy because it offers learners opportunities to develop their proficiency with complex high-level cognitive processes. One has always associated the ability to make mathematical connections, together with the teacher's role in teaching them, with deep mathematical understanding. This article examines the nature and quality of the mathematical connections that the teachers' representations of those connections enabled or constrained. The researchers made video recordings of four Grade 11 teachers as they taught a series of five lessons on algebra-related topics. The results showed that the teachers' representations of mathematical connections were either faulty or superficial in most cases. It compromised the learners' opportunities for making meaningful mathematical connections. The researchers concluded by suggesting that helping teachers to build their representation repertoires could increase the effectiveness of their instructional practices.
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- Date Issued: 2012
Enhancing the Configuration and Design of Sound Systems through Simulation
- Authors: Otten, Frederick , Foss, Richard
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427125 , vital:72416 , https://www.aes.org/e-lib/browse.cfm?elib=15848
- Description: Audio Engineers are required to design and deploy large multi-channel sound systems which meet a set of requirements and use networking technologies such as Firewire and Ethernet. Bandwidth utilsation and latency need to be considered. Network Simulation can be used to accurately model a network and return such information. This paper discusses a software system which has been developed to create a simulation of a network using the AES-X170 protocol for command and control. This system shows information about bandwidth and latency and is able to detect problems with parameter relationships. It also provides the ability to perform offline editing. These features significantly enhance audio engineers' ability to effectively design, configure and evaluate sound systems.
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- Date Issued: 2011
Network neutral control over quality of service networks
- Authors: Foulkes, Phillip , Foss, Richard , Gurdan, Robby
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427166 , vital:72419 , https://www.aes.org/e-lib/online/browse.cfm?elib=16151
- Description: Creating interoperability between two standards-based network technologies, IEEE 1394 Firewire and Ethernet Audio/Video Bridging (AVB), allows them to exist simultaneously in a single application configuration. While both technologies provide the transport of synchronized, low-latency, real-time audio and video data, they have different approaches to enabling this transport. By using a compatible audio gateway with a common control protocol, audio devices on these disparate networks can be connected and controlled.
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- Date Issued: 2011
The PINIT domain of PIAS3: structure-function analysis of its interaction with STAT3
- Authors: Mautsa, Nicodemus , Prinsloo, Earl , Tastan Bishop, Özlem , Blatch, Gregory L
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148082 , vital:38708 , DOI: 10.1002/jmr.1111
- Description: The protein inhibitor of activated signal transducer and activator of transcription 3 (PIAS3) regulates the transcriptional activity of signal transducer and activator of transcription 3 (STAT3) which regulates transcription of genes involved in cell growth, proliferation and apoptosis. The conserved proline, isoleucine, asparagine, isoleucine, threonine (PINIT) domain of PIAS3 is thought to promote STAT3–PIAS3 interaction.
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- Date Issued: 2011
The xfn connection management and control protocol
- Authors: Foss, Richard , Gurdan, Robby , Klinkradt, Bradley , Chigwamba, Nyasha
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427137 , vital:72417 , https://www.aes.org/e-lib/browse.cfm?elib=16143
- Description: With the advent of digital networks that link audio devices, there is a need for a protocol that integrates control and connection management, enables the streaming of all media content such as audio and video between devices from different manufacturers, and that provides a common approach to the control of these devices. This paper describes such a protocol, named XFN, currently being standardized as part of the AES X170 project. XFN is an IP-based peer to peer network protocol, in which any device on the network may send or receive connection management, control, and monitoring messages. Essential to the XFN protocol is the fact that each parameter in a device can be addressed via a hierarchical structure that reflects the functional layout of the device.
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- Date Issued: 2011
Towards a standard model for networked audio devices
- Authors: Eales, Andrew , Foss, Richard
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427151 , vital:72418 , https://www.aes.org/e-lib/online/browse.cfm?elib=16144
- Description: Different control protocols for networked audio devices typically emphasize particular aspects of a device, such as the representation of parameter data, or a representation of the functional structure of a device. A sophisticated device model must represent parameter data, device structure and the visual presentation of controls. Parameter data should be related to the device structure, while also being represented within a flexible, logical hierarchy. The development of a standard device model is proposed and discussed with reference to the OSC, IEC62379, ACN and X170 control protocols. This abstract model is independent of any specific control protocol, and provides support for interoperability between control protocols. The proposed model is also discussed within the context of an object-based approach to service enumeration and control using an associative, shared memory model.
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- Date Issued: 2011
When breast is not best: young women and breast reduction surgery
- Authors: Lamb, Tessa , Vincent, Louise
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141832 , vital:38008 , DOI: 10.1080/10130950.2011.610978
- Description: Most cosmetic surgery patients in South Africa are younger than 21, and in this focus we examine narrative accounts from young South African women who have chosen to undergo cosmetic breast reduction surgery. Feminist debates on cosmetic surgery have focused on the question of whether to regard women who modify their bodies in this way as active agents engaged in liberatory ‘body projects’, or whether such projects are evidence of their subjection to oppressive stereotypes and beauty norms. The latter perspective is challenged here by the participants’ characterisation of breast reduction surgery as profoundly ‘freeing’. The article deals in particular with the conscious choice of participants to knowingly risk not being able to breastfeed children in future in order to achieve a body type which conforms to their understanding of youthful beauty and sexuality.
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- Date Issued: 2011