Pessimistic assessment of white shark population status in South Africa: comment on Andreotti et al.(2016)
- Authors: Irion, Dylan T , Noble, Leslie R , Kock, Alison A , Gennari, Enrico , Dicken, Matthew L , Hewitt, Adrian M , Towner, Alison V , Booth, Anthony J , Smale, Malcolm J , Cliff, Geremy
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:35799 , https://doi.10.3354/meps12283
- Description: Andreotti et al. (2016; Mar Ecol Prog Ser 552:241−253) estimate an abundance (N) of 438 white sharks Carcharodon carcharias and a contemporary effective population size (CNe) of 333 individuals along the South African coast. N was estimated by using a mark-recapture analysis of photographic identification records from a single aggregation site (Gansbaai). CNe was calculated based on the levels of pairwise linkage disequilibrium of genetic material collected from 4 aggregation sites across approximately 965 km of South African coastline. However, due to the complex stock structure of white sharks and the model assumptions made by Andreotti et al. (2016), the conclusions drawn cannot be supported by their methods and data.
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A sharing platform for Indicators of Compromise
- Authors: Rudman, Lauren , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427831 , vital:72465 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622961_A_sharing_platform_for_Indicators_of_Compromise/links/5b9a1ad1a6fdcc59bf8dfe51/A-sharing-platform-for-Indicators-of-Compromise.pdf
- Description: In this paper, we will describe the functionality of a proof of concept sharing platform for sharing cyber threat information. Information is shared in the Structured Threat Information eXpression (STIX) language displayed in HTML. We focus on the sharing of network Indicators of Compromise generated by malware samples. Our work is motivated by the need to provide a platform for exchanging comprehensive network level Indicators. Accordingly we demonstrate the functionality of our proof of concept project. We will discuss how to use some functions of the platform, such as sharing STIX Indicators, navigating around and downloading defense mechanisims. It will be shown how threat information can be converted into different formats to allow them to be used in firewall and Intrusion Detection System (IDS) rules. This is an extension to the sharing platform and makes the creation of network level defense mechanisms efficient. Two API functions of the platform will be successfully tested and are useful because this can allow for the bulk sharing and of threat information.
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Assimilation of organic and inorganic nutrients by Erica root fungi from the fynbos ecosystem
- Authors: Bizabani, Christine , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444079 , vital:74183 , https://doi.org/10.1016/j.funbio.2015.11.006
- Description: Erica dominate the fynbos ecosystem, which is characterized by acidic soils that are rich in organic matter. The ericaceae associate with ericoid mycorrhizal (ERM) fungi for survival. In this study fungal biomass accumulation in vitro was used to determine nutrient utilisation of various inorganic and organic substrates. This is an initial step towards establishment of the ecological roles of typical ERM fungi and other root fungi associated with Erica plants, with regard to host nutrition. Meliniomyces sp., Acremonium implicatum, Leohumicola sp., Cryptosporiopsis erica, Oidiodendron maius and an unidentified Helotiales fungus were selected from fungi previously isolated and identified from Erica roots. Sole nitrogen sources ammonium, nitrate, arginine and Bovine Serum Albumin (BSA) were tested. Meliniomyces and Leohumicola species were able to utilise BSA effectively. Phosphorus nutrition was tested using orthophosphate, sodium inositol hexaphosphate and DNA. Most isolates preferred orthophosphate. Meliniomyces sp. and A. implicatum were able to accumulate significant biomass using DNA. Carbon utilisation was tested using glucose, cellobiose, carboxymethylcellulose, pectin and tannic acid substrates. All fungal isolates produced high biomass on glucose and cellobiose. The ability to utilize organic nutrient sources in culture, illustrates their potential role of these fungi in host nutrition in the fynbos ecosystem.
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Cytotoxic activity of marine sponge extracts from the sub-Antarctic Islands and the Southern Ocean
- Authors: Olsen, Elisabeth , De Cerf, Christopher , Dziwornu, Godwin , Puccinelli, Eleonora , Parker-Nance, Shirley , Ansorge, Isabelle J , Samaai, Toufiek , Dingle, Laura , Edkins, Adrienne L , Sunassee, Suthananda N
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66300 , vital:28931 , https://doi.org/10.17159/sajs.2016/20160202
- Description: publisher version , Over the past 50 years, marine invertebrates, especially sponges, have proven to be a valuable source of new and/or bioactive natural products that have the potential to be further developed as lead compounds for pharmaceutical applications. Although marine benthic invertebrate communities occurring off the coast of South Africa have been explored for their biomedicinal potential, the natural product investigation of marine sponges from the sub-Antarctic Islands in the Southern Ocean for the presence of bioactive secondary metabolites has been relatively unexplored thus far. We report here the results for the biological screening of both aqueous and organic extracts prepared from nine specimens of eight species of marine sponges, collected from around Marion Island and the Prince Edward Islands in the Southern Ocean, for their cytotoxic activity against three cancer cell lines. The results obtained through this multidisciplinary collaborative research effort by exclusively South African institutions has provided an exciting opportunity to discover cytotoxic compounds from sub-Antarctic sponges, whilst contributing to our understanding of the biodiversity and geographic distributions of these cold-water invertebrates. Therefore, we acknowledge here the various contributions of the diverse scientific disciplines that played a pivotal role in providing the necessary platform for the future natural products chemistry investigation of these marine sponges from the sub- Antarctic Islands and the Southern Ocean. Significance: This study will contribute to understanding the biodiversity and geographic distributions of sponges in the Southern Ocean. This multidisciplinary project has enabled the investigation of marine sponges for the presence of cytotoxic compounds. Further investigation will lead to the isolation and identification of cytotoxic compounds present in the active sponge extracts. , University of Cape Town; South African Medical Research Council; National Research Foundation (South Africa); CANSA; Rhodes University; Department of Science and Technology; Department of Environmental Affairs; SANAP
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Design of a Configurable Embedded Network Tap Flow Generation using NetFlow v9 and IPFIX Formats
- Authors: Pennefather, Sean , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427756 , vital:72460 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622779_Design_of_a_Configurable_Embedded_Network_Tap_Flow_Generation_using_NetFlow_v9_and_IPFIX_Formats/links/5b9a19f2299bf14ad4d6a591/Design-of-a-Configurable-Embedded-Network-Tap-Flow-Generation-using-NetFlow-v9-and-IPFIX-Formats.pdf
- Description: This paper describes the design of a $200 hardware apparatus capable of passively monitoring network transmission at wire speeds of 100Mbit/s and generating NetFlow v9 or IPFIX compliant network flows for a downstream monitoring infrastructure. Testing of the apparatus hardware confirmed no network disruptions regardless of operational or power state while still being capable of correctly monitoring network traffic when configured. System testing under situations of heavy load confirmed apparatus capability at monitoring network traffic and correct generation of network flows compliant with either NetFlow v9 or IPFIX standards.
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E-Government as a Means to Support Communal, Large ICT Infrastructure in Poor Areas
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo , Tsietsi, Mosiuoa
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431287 , vital:72761 , https://www.academic-bookshop.com/ourshop/prod_5067238-ECEG-2016-Proceedings-of-the-16th-European-Conference-on-eGovernment.html
- Description: Citizen-facing e-Government appears inevitable given current technol-ogy trends, and certainly has many advantages. One overlooked bene-fit, in our opinion, is its potential to make financially viable communal “large ICT” installations, which would diffuse ICT in poor communities where ICT is currently absent.(By “large ICT” we refer to end-user equipment such as desktops or laptops, on which would be possible to produce content, including software. The presence of “large ICT” in a community is critical in our opinion for the empowerment of the commu-nity, especially its younger component.) This paper explores this poten-tial in e-Government, describing a model conceptualized in the Siyakhu-la Living Lab in South Africa and partially implemented, through an inte-gration platform named “TeleWeaver”. The model behind TeleWeaver is an adaptation of the classic Internet business model-whereby users of services do not directly pay for the services they use. This model is especially relevant currently in South Africa, because of the an-nouncement by the government to pilot connecting to the internet gov-ernment facilities, including schools, in eight poor district municipalities.
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Land acquisition for and local livelihood implications of biofuel development in Zimbabwe
- Authors: Thondhlana, Gladman
- Date: 2016
- Subjects: Biomass energy -- Government policy -- Zimbabwe Biomass energy -- Economic aspects -- Zimbabwe Biomass energy -- Environmental aspects -- Zimbabwe
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/49940 , vital:25944
- Description: In recent years, proponents of 'green and clean fuel' have argued that the costs of overreliance on fossil fuels could be reduced through transition to biofuels such as bio-ethanol. Global biofuel discourses suggest that any transition to biofuel invariably results in significant benefits, including energy independence, job creation, development of agro-industrial centres at local level and high revenue generations for the state with minimum negative impacts on the environment. With many risks and costs associated with traditional 'dirty' fuels, it is likely that many countries, particularly African countries, will move towards the 'green and clean fuel' alternative. However, until recently research has arguably paid limited attention to the local livelihood impacts related to land acquisition for biofuel development or the policy frameworks required to maximise biofuel benefits. With regards to biofuel benefits, some recent studies suggest that the much bandied potential for greater tax revenue, lowered fuel costs and wealth distribution from biofuel production have all been perverted with relatively little payoff in wage labour opportunities in return (e.g. Richardson, 2010; Wilkinson and Herrera, 2010). Based on work done in Chisumbanje communal lands of Zimbabwe (Thondhlana, 2015), this policy brief highlights the local livelihood impacts of biofuel development and discusses policy implications of the findings. By highlighting the justifications of biofuel development at any cost by the state, the study sheds some light on the conflicts between state interests and local livelihood needs.
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Sha-1 and the strict avalanche criterion
- Authors: Motara, Yusuf, M , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429010 , vital:72553 , https://ieeexplore.ieee.org/abstract/document/7802926
- Description: The Strict Avalanche Criterion (SAC) is a measure of both confusion and diffusion, which are key properties of a cryptographic hash function. This work provides a working definition of the SAC, describes an experimental methodology that can be used to statistically evaluate whether a cryptographic hash meets the SAC, and uses this to investigate the degree to which compression function of the SHA-1 hash meets the SAC. The results (P 0.01) are heartening: SHA-1 closely tracks the SAC after the first 24 rounds, and demonstrates excellent properties of confusion and diffusion throughout.
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