M 87 at metre wavelengths: the LOFAR picture
- Smirnov, Oleg M, De Gasperin, F, Orrú, E, Murgia, M, Merloni, A, Falcke, H, Beck, R, Beswick, R, Bîrzan, L, Bonafede, A, Brüggen, M
- Authors: Smirnov, Oleg M , De Gasperin, F , Orrú, E , Murgia, M , Merloni, A , Falcke, H , Beck, R , Beswick, R , Bîrzan, L , Bonafede, A , Brüggen, M
- Date: 2012
- Subjects: radiation mechanisms: non-thermal, galaxies: active, galaxies: individual: M 87, galaxies: clusters: individual: Virgo, galaxies: jets, radio continuum: galaxies
- Language: English
- Type: Article
- Identifier: vital:6821 , http://hdl.handle.net/10962/d1004434
- Description: Context.M 87 is a giant elliptical galaxy located in the centre of the Virgo cluster, which harbours a supermassive black hole of mass 6.4 × 109 M⊙, whose activity is responsible for the extended (80 kpc) radio lobes that surround the galaxy. The energy generated by matter falling onto the central black hole is ejected and transferred to the intra-cluster medium via a relativistic jet and morphologically complex systems of buoyant bubbles, which rise towards the edges of the extended halo. Aims. To place constraints on past activity cycles of the active nucleus, images of M 87 were produced at low radio frequencies never explored before at these high spatial resolution and dynamic range. To disentangle different synchrotron models and place constraints on source magnetic field, age and energetics, we also performed a detailed spectral analysis of M 87 extended radio-halo. Methods. We present the first observations made with the new Low-Frequency Array (LOFAR) of M 87 at frequencies down to 20 MHz. Three observations were conducted, at 15−30 MHz, 30−77 MHz and 116−162 MHz. We used these observations together with archival data to produce a low-frequency spectral index map and to perform a spectral analysis in the wide frequency range 30 MHz–10 GHz. Results. We do not find any sign of new extended emissions; on the contrary the source appears well confined by the high pressure of the intra-cluster medium. A continuous injection of relativistic electrons is the model that best fits our data, and provides a scenario in which the lobes are still supplied by fresh relativistic particles from the active galactic nuclei. We suggest that the discrepancy between the low-frequency radio-spectral slope in the core and in the halo implies a strong adiabatic expansion of the plasma as soon as it leaves the core area. The extended halo has an equipartition magnetic field strength of ≃10 μG, which increases to ≃13 μG in the zones where the particle flows are more active. The continuous injection model for synchrotron ageing provides an age for the halo of ≃40 Myr, which in turn provides a jet kinetic power of 6−10 × 1044 erg s-1.
- Full Text:
- Date Issued: 2012
- Authors: Smirnov, Oleg M , De Gasperin, F , Orrú, E , Murgia, M , Merloni, A , Falcke, H , Beck, R , Beswick, R , Bîrzan, L , Bonafede, A , Brüggen, M
- Date: 2012
- Subjects: radiation mechanisms: non-thermal, galaxies: active, galaxies: individual: M 87, galaxies: clusters: individual: Virgo, galaxies: jets, radio continuum: galaxies
- Language: English
- Type: Article
- Identifier: vital:6821 , http://hdl.handle.net/10962/d1004434
- Description: Context.M 87 is a giant elliptical galaxy located in the centre of the Virgo cluster, which harbours a supermassive black hole of mass 6.4 × 109 M⊙, whose activity is responsible for the extended (80 kpc) radio lobes that surround the galaxy. The energy generated by matter falling onto the central black hole is ejected and transferred to the intra-cluster medium via a relativistic jet and morphologically complex systems of buoyant bubbles, which rise towards the edges of the extended halo. Aims. To place constraints on past activity cycles of the active nucleus, images of M 87 were produced at low radio frequencies never explored before at these high spatial resolution and dynamic range. To disentangle different synchrotron models and place constraints on source magnetic field, age and energetics, we also performed a detailed spectral analysis of M 87 extended radio-halo. Methods. We present the first observations made with the new Low-Frequency Array (LOFAR) of M 87 at frequencies down to 20 MHz. Three observations were conducted, at 15−30 MHz, 30−77 MHz and 116−162 MHz. We used these observations together with archival data to produce a low-frequency spectral index map and to perform a spectral analysis in the wide frequency range 30 MHz–10 GHz. Results. We do not find any sign of new extended emissions; on the contrary the source appears well confined by the high pressure of the intra-cluster medium. A continuous injection of relativistic electrons is the model that best fits our data, and provides a scenario in which the lobes are still supplied by fresh relativistic particles from the active galactic nuclei. We suggest that the discrepancy between the low-frequency radio-spectral slope in the core and in the halo implies a strong adiabatic expansion of the plasma as soon as it leaves the core area. The extended halo has an equipartition magnetic field strength of ≃10 μG, which increases to ≃13 μG in the zones where the particle flows are more active. The continuous injection model for synchrotron ageing provides an age for the halo of ≃40 Myr, which in turn provides a jet kinetic power of 6−10 × 1044 erg s-1.
- Full Text:
- Date Issued: 2012
Mitochondrial DNA paradox: sex-specific genetic structure in a marine mussel despite maternal inheritance and passive dispersal
- Teske, Peter R, Papadopoulos, Isabelle, Barker, Nigel P, McQuaid, Christopher D
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Barker, Nigel P , McQuaid, Christopher D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6836 , http://hdl.handle.net/10962/d1010959
- Description: Background: When genetic structure is identified using mitochondrial DNA (mtDNA), but no structure is identified using biparentally-inherited nuclear DNA, the discordance is often attributed to differences in dispersal potential between the sexes. Results: We sampled the intertidal rocky shore mussel Perna perna in a South African bay and along the nearby open coast, and sequenced maternally-inherited mtDNA (there is no evidence for paternally-inherited mtDNA in this species) and a biparentally-inherited marker. By treating males and females as different populations, we identified significant genetic structure on the basis of mtDNA data in the females only. Conclusions: This is the first study to report sex-specific differences in genetic structure based on matrilineally-inherited mtDNA in a passively dispersing species that lacks social structure or sexual dimorphism. The observed pattern most likely stems from females being more vulnerable to selection in habitats from which they did not originate, which also manifests itself in a male-biased sex ratio. Our results have three important implications for the interpretation of population genetic data. First, even when mtDNA is inherited exclusively in the female line, it also contains information about males. For that reason, using it to identify sex-specific differences in genetic structure by contrasting it with biparentally-inherited markers is problematic. Second, the fact that sex-specific differences were found in a passively dispersing species in which sex-biased dispersal is unlikely highlights the fact that significant genetic structure is not necessarily a function of low dispersal potential or physical barriers. Third, even though mtDNA is typically used to study historical demographic processes, it also contains information about contemporary processes. Higher survival rates of males in non-native habitats can erase the genetic structure present in their mothers within a single generation.
- Full Text:
- Date Issued: 2012
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Barker, Nigel P , McQuaid, Christopher D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6836 , http://hdl.handle.net/10962/d1010959
- Description: Background: When genetic structure is identified using mitochondrial DNA (mtDNA), but no structure is identified using biparentally-inherited nuclear DNA, the discordance is often attributed to differences in dispersal potential between the sexes. Results: We sampled the intertidal rocky shore mussel Perna perna in a South African bay and along the nearby open coast, and sequenced maternally-inherited mtDNA (there is no evidence for paternally-inherited mtDNA in this species) and a biparentally-inherited marker. By treating males and females as different populations, we identified significant genetic structure on the basis of mtDNA data in the females only. Conclusions: This is the first study to report sex-specific differences in genetic structure based on matrilineally-inherited mtDNA in a passively dispersing species that lacks social structure or sexual dimorphism. The observed pattern most likely stems from females being more vulnerable to selection in habitats from which they did not originate, which also manifests itself in a male-biased sex ratio. Our results have three important implications for the interpretation of population genetic data. First, even when mtDNA is inherited exclusively in the female line, it also contains information about males. For that reason, using it to identify sex-specific differences in genetic structure by contrasting it with biparentally-inherited markers is problematic. Second, the fact that sex-specific differences were found in a passively dispersing species in which sex-biased dispersal is unlikely highlights the fact that significant genetic structure is not necessarily a function of low dispersal potential or physical barriers. Third, even though mtDNA is typically used to study historical demographic processes, it also contains information about contemporary processes. Higher survival rates of males in non-native habitats can erase the genetic structure present in their mothers within a single generation.
- Full Text:
- Date Issued: 2012
Pre-concentration of toxic metals using electrospun amino-functionalized nylon-6 nanofibre sorbent
- Darko, G, Sobola, A, Adewuyi, Sheriff, Okonkwo, J O, Torto, N
- Authors: Darko, G , Sobola, A , Adewuyi, Sheriff , Okonkwo, J O , Torto, N
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6571 , http://hdl.handle.net/10962/d1004134
- Description: This paper presents a new approach for pre-concentrating toxic metals (As, Cd, Ni and Pb) in aqueous environments using an amino-functionalized electrospun nanofibre sorbent. The sorbent, composed of nanofibres of average diameter 80 ± 10 nm and specific surface area of 58m2 g–1, exhibited fast adsorption kinetics (<20 min) for As, Cd, Ni and Pb. The optimalpHfor the uptake of As, Cd, Ni and Pb were 5.5, 6.0, 6.5 and 11, respectively. The adsorption process best fitted the Freundlich isothermand followed the first-order kinetics. The highest pre-concentration achieved using the sorbent was 41.99 (Ni in treated wastewater). The capacity of the sorbent to pre-concentrate the toxic metals was compared with those of aqua regia and HNO3+H2O2 digestions. The pre-concentration factors achieved for Cd in river water samples can be ranked as aqua regia digestion (0.73) > adsorption (0.34)>HNO3+H2O2 (0.23) digestion.Asimilar trend was observed for Ni in river water as well as Ni andCdin tap water samples. Pb ions in the river water samples were pre-concentrated slightly better using the two digestion methods pre-concentration factors ~22) compared to adsorption method (pre-concentration factor ~21). The use of the electrospun amino-functionalized nanofibre sorbent presentsanefficientand cost-effective alternative for pre-concentration of toxic metals inaqueousenvironments.
- Full Text:
- Date Issued: 2012
- Authors: Darko, G , Sobola, A , Adewuyi, Sheriff , Okonkwo, J O , Torto, N
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6571 , http://hdl.handle.net/10962/d1004134
- Description: This paper presents a new approach for pre-concentrating toxic metals (As, Cd, Ni and Pb) in aqueous environments using an amino-functionalized electrospun nanofibre sorbent. The sorbent, composed of nanofibres of average diameter 80 ± 10 nm and specific surface area of 58m2 g–1, exhibited fast adsorption kinetics (<20 min) for As, Cd, Ni and Pb. The optimalpHfor the uptake of As, Cd, Ni and Pb were 5.5, 6.0, 6.5 and 11, respectively. The adsorption process best fitted the Freundlich isothermand followed the first-order kinetics. The highest pre-concentration achieved using the sorbent was 41.99 (Ni in treated wastewater). The capacity of the sorbent to pre-concentrate the toxic metals was compared with those of aqua regia and HNO3+H2O2 digestions. The pre-concentration factors achieved for Cd in river water samples can be ranked as aqua regia digestion (0.73) > adsorption (0.34)>HNO3+H2O2 (0.23) digestion.Asimilar trend was observed for Ni in river water as well as Ni andCdin tap water samples. Pb ions in the river water samples were pre-concentrated slightly better using the two digestion methods pre-concentration factors ~22) compared to adsorption method (pre-concentration factor ~21). The use of the electrospun amino-functionalized nanofibre sorbent presentsanefficientand cost-effective alternative for pre-concentration of toxic metals inaqueousenvironments.
- Full Text:
- Date Issued: 2012
Prediction of water temperature metrics using spatial modelling in the Eastern and Western Cape, South Africa
- Rivers-Moore, N A, Mantel, S, Dallas, H F
- Authors: Rivers-Moore, N A , Mantel, S , Dallas, H F
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7071 , http://hdl.handle.net/10962/d1003947 , http://www.scielo.org.za/scielo.php?pid=S1816-79502012000200002&script=sci_arttext
- Description: Key aspects of a river's temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal metrics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water temperature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readily-mapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa. These metrics were correlated with 16 environmental variables. Correlations enabled development of multiple regression models which facilitated mapping of temperature metrics over the study area. This approach has the potential to be applied at a national scale as more thermal time series are collected nationally. It is argued that the appropriateness of management decisions in rivers can be improved by including guidelines for thermal metrics at a regional scale. Such maps could facilitate incorporation of a temperature component into management guidelines for water resources.
- Full Text:
- Date Issued: 2012
- Authors: Rivers-Moore, N A , Mantel, S , Dallas, H F
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7071 , http://hdl.handle.net/10962/d1003947 , http://www.scielo.org.za/scielo.php?pid=S1816-79502012000200002&script=sci_arttext
- Description: Key aspects of a river's temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal metrics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water temperature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readily-mapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa. These metrics were correlated with 16 environmental variables. Correlations enabled development of multiple regression models which facilitated mapping of temperature metrics over the study area. This approach has the potential to be applied at a national scale as more thermal time series are collected nationally. It is argued that the appropriateness of management decisions in rivers can be improved by including guidelines for thermal metrics at a regional scale. Such maps could facilitate incorporation of a temperature component into management guidelines for water resources.
- Full Text:
- Date Issued: 2012
Rights discourses in relation to people with intellectual disability: towards an ethics of relations, critique and care
- Mckenzie, Judith A, Macleod, Catriona I
- Authors: Mckenzie, Judith A , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6282 , http://hdl.handle.net/10962/d1014123 , http://dx.doi.org/10.1080/09687599.2012.631795
- Description: In this paper we argue that human rights approaches for intellectually disabled people have failed to recognise the complexity of rights claims made by and on behalf of this group. Drawing on a research project into discourses of education for intellectually disabled people in the Eastern Cape, South Africa we discern three rights discourses; namely, rights to full participation, rights to special services and rights to protection. These draw off a social model, a medical model and a protective model, respectively. We note that these discourses may be set up in contestation with each other. However, we argue that they can be seen as complementary if viewed within an ethics of care that enables participation. Within this conceptualisation, participation is viewed within relations of care but is subject to a critique that examines the role of context and disciplinary power in constructing dependency.
- Full Text:
- Date Issued: 2012
- Authors: Mckenzie, Judith A , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6282 , http://hdl.handle.net/10962/d1014123 , http://dx.doi.org/10.1080/09687599.2012.631795
- Description: In this paper we argue that human rights approaches for intellectually disabled people have failed to recognise the complexity of rights claims made by and on behalf of this group. Drawing on a research project into discourses of education for intellectually disabled people in the Eastern Cape, South Africa we discern three rights discourses; namely, rights to full participation, rights to special services and rights to protection. These draw off a social model, a medical model and a protective model, respectively. We note that these discourses may be set up in contestation with each other. However, we argue that they can be seen as complementary if viewed within an ethics of care that enables participation. Within this conceptualisation, participation is viewed within relations of care but is subject to a critique that examines the role of context and disciplinary power in constructing dependency.
- Full Text:
- Date Issued: 2012
Surface electrochemistry : structured electrode, synthesis, and characterization
- Bedioui, Fethi, Nyokong, Tebello, Zagal, Jose H
- Authors: Bedioui, Fethi , Nyokong, Tebello , Zagal, Jose H
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6567 , http://hdl.handle.net/10962/d1004126 , http://dx.doi.org/10.1155/2012/405825
- Description: From introduction: The aim of this special issue is to show, through recent updated significant examples, how the electrochemical techniques allow the unique characterization of specific properties of micro- and nanostructured materials that offer varied possibilities of uses and the preparation of specific types of ordered materials that take advantage of electrochemical synthetic methods such as structuring nanosized wires and dots, to cite only two examples.
- Full Text:
- Date Issued: 2012
- Authors: Bedioui, Fethi , Nyokong, Tebello , Zagal, Jose H
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6567 , http://hdl.handle.net/10962/d1004126 , http://dx.doi.org/10.1155/2012/405825
- Description: From introduction: The aim of this special issue is to show, through recent updated significant examples, how the electrochemical techniques allow the unique characterization of specific properties of micro- and nanostructured materials that offer varied possibilities of uses and the preparation of specific types of ordered materials that take advantage of electrochemical synthetic methods such as structuring nanosized wires and dots, to cite only two examples.
- Full Text:
- Date Issued: 2012
The deployment of the medico-psychological gaze and disability expertise in relation to children with intellectual disability
- Mckenzie, Judith A, Macleod, Catriona I
- Authors: Mckenzie, Judith A , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6294 , http://hdl.handle.net/10962/d1014732 , http://www.tandfonline.com/doi/full/10.1080/13603116.2010.540042
- Description: In this study, we adopt the concepts of Michel Foucault on the medical gaze and Nikolas Rose on psychological expertise to differentiate between two forms of expertise evident in the education of intellectually disabled children. We draw on a discourse analytic study carried out in South Africa on intellectual disability in relation to educational practice to examine the operation of a medico-psychological gaze that calls for disability expertise in the management of disability. We conclude our discussion by noting that the dichotomy between impairment and disability that is proposed in the social model of disability does little to destabilise the power of the medico-psychological gaze since impairment is conceded to biomedical knowledge as an object of positive knowledge. This tacit acceptance of the medical authority gives sanction to disability expertise that operates in diffuse ways to regulate the educational experience of learners with intellectual disability. The implications of this conception for inclusive education are briefly explored, and further areas for research are suggested.
- Full Text:
- Date Issued: 2012
- Authors: Mckenzie, Judith A , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6294 , http://hdl.handle.net/10962/d1014732 , http://www.tandfonline.com/doi/full/10.1080/13603116.2010.540042
- Description: In this study, we adopt the concepts of Michel Foucault on the medical gaze and Nikolas Rose on psychological expertise to differentiate between two forms of expertise evident in the education of intellectually disabled children. We draw on a discourse analytic study carried out in South Africa on intellectual disability in relation to educational practice to examine the operation of a medico-psychological gaze that calls for disability expertise in the management of disability. We conclude our discussion by noting that the dichotomy between impairment and disability that is proposed in the social model of disability does little to destabilise the power of the medico-psychological gaze since impairment is conceded to biomedical knowledge as an object of positive knowledge. This tacit acceptance of the medical authority gives sanction to disability expertise that operates in diffuse ways to regulate the educational experience of learners with intellectual disability. The implications of this conception for inclusive education are briefly explored, and further areas for research are suggested.
- Full Text:
- Date Issued: 2012
The distribution, habitat, diet and forensic significance of the scarab Frankenbergerius forcipatus (Harold, 1881) (Coleoptera : Scarabaeidae)
- Midgley, John M, Collett, I J, Villet, Martin H
- Authors: Midgley, John M , Collett, I J , Villet, Martin H
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6842 , http://hdl.handle.net/10962/d1010992
- Description: Records of African beetles feeding on carrion are scattered and incomplete, but important to forensic entomology. Thirty-three specimens of Frankenbergerius forcipatus (Harold, 1881) were found on carrionnear Grahamstown, Eastern Cape, South Africa, providing new insight into the distribution (hills and mountains), habitat (fynbos and forest), biology (generalist on decaying material) and forensic significance (wet-decay, late opportunist) of the species.
- Full Text:
- Date Issued: 2012
- Authors: Midgley, John M , Collett, I J , Villet, Martin H
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6842 , http://hdl.handle.net/10962/d1010992
- Description: Records of African beetles feeding on carrion are scattered and incomplete, but important to forensic entomology. Thirty-three specimens of Frankenbergerius forcipatus (Harold, 1881) were found on carrionnear Grahamstown, Eastern Cape, South Africa, providing new insight into the distribution (hills and mountains), habitat (fynbos and forest), biology (generalist on decaying material) and forensic significance (wet-decay, late opportunist) of the species.
- Full Text:
- Date Issued: 2012
The NINJA-2 catalog of hybrid post-Newtonian/numerical-relativity waveforms for non-precessing black-hole binaries
- Ajith, P, Boyle, M, Brown, Dane A, Buchman, L T, Pollney, D
- Authors: Ajith, P , Boyle, M , Brown, Dane A , Buchman, L T , Pollney, D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6788 , http://hdl.handle.net/10962/d1006940
- Description: The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational wave data analysis communities. The purpose of NINJA is to study the sensitivity of existing gravitational-wave search and parameter-estimation algorithms using numerically generated waveforms, and to foster closer collaboration between the numerical relativity and data analysis communities. The first NINJA project used only a small number of injections of short numerical-relativity waveforms, which limited its ability to draw quantitative conclusions. The goal of the NINJA-2 project is to overcome these limitations with long post-Newtonian - numerical relativity hybrid waveforms, large numbers of injections, and the use of real detector data. We report on the submission requirements for the NINJA-2 project and the construction of the waveform catalog. Eight numerical relativity groups have contributed 63 hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. We summarize the techniques used by each group in constructing their submissions. We also report on the procedures used to validate these submissions, including examination in the time and frequency domains and comparisons of waveforms from different groups against each other. These procedures have so far considered only the $(ell,m)=(2,2)$ mode. Based on these studies we judge that the hybrid waveforms are suitable for NINJA-2 studies. We note some of the plans for these investigations.
- Full Text:
- Date Issued: 2012
- Authors: Ajith, P , Boyle, M , Brown, Dane A , Buchman, L T , Pollney, D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6788 , http://hdl.handle.net/10962/d1006940
- Description: The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational wave data analysis communities. The purpose of NINJA is to study the sensitivity of existing gravitational-wave search and parameter-estimation algorithms using numerically generated waveforms, and to foster closer collaboration between the numerical relativity and data analysis communities. The first NINJA project used only a small number of injections of short numerical-relativity waveforms, which limited its ability to draw quantitative conclusions. The goal of the NINJA-2 project is to overcome these limitations with long post-Newtonian - numerical relativity hybrid waveforms, large numbers of injections, and the use of real detector data. We report on the submission requirements for the NINJA-2 project and the construction of the waveform catalog. Eight numerical relativity groups have contributed 63 hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. We summarize the techniques used by each group in constructing their submissions. We also report on the procedures used to validate these submissions, including examination in the time and frequency domains and comparisons of waveforms from different groups against each other. These procedures have so far considered only the $(ell,m)=(2,2)$ mode. Based on these studies we judge that the hybrid waveforms are suitable for NINJA-2 studies. We note some of the plans for these investigations.
- Full Text:
- Date Issued: 2012
The use of response surface methodology to evaluate the impact of level 2 SUPAC–IR changes on the in vitro release of metronidazole and ranitidine from a fixed-dose combination tablet
- King’ori, Loti D, Walker, Roderick B
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
- Full Text:
- Date Issued: 2012
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
- Full Text:
- Date Issued: 2012
Three tales of Theal: biography, history and ethnography on the Eastern Frontier
- Authors: Naidu, Samantha
- Date: 2012
- Language: English
- Type: Article , text
- Identifier: vital:24529 , http://hdl.handle.net/10962/36216 , https://www.jstor.org/stable/23267873?seq=1#page_scan_tab_contents , https://orcid.org/0000-0001-9456-8657
- Full Text:
- Date Issued: 2012
- Authors: Naidu, Samantha
- Date: 2012
- Language: English
- Type: Article , text
- Identifier: vital:24529 , http://hdl.handle.net/10962/36216 , https://www.jstor.org/stable/23267873?seq=1#page_scan_tab_contents , https://orcid.org/0000-0001-9456-8657
- Full Text:
- Date Issued: 2012
Treating complex post-traumatic stress disorder following childhood neglect, sexual abuse and revictimisation : interpretative reflections on the case of Khuselwa
- Padmanabhanunni, A, Edwards, David J A
- Authors: Padmanabhanunni, A , Edwards, David J A
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6233 , http://hdl.handle.net/10962/d1007783
- Description: This paper describes the psychological assessment and treatment process with Khuselwa, a South African adolescent survivor of multiple sexual traumas presenting with complex post-traumatic stress disorder (PTSD). The paper identifies some of the common barriers encountered by practitioners in delivering treatments in local contexts and highlights the role of external safety and stability and social support in providing a vehicle for change and a basis for overcoming the psychological handicaps reinforced by repeated and multiple traumas and chronic neglect.
- Full Text:
- Date Issued: 2012
- Authors: Padmanabhanunni, A , Edwards, David J A
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6233 , http://hdl.handle.net/10962/d1007783
- Description: This paper describes the psychological assessment and treatment process with Khuselwa, a South African adolescent survivor of multiple sexual traumas presenting with complex post-traumatic stress disorder (PTSD). The paper identifies some of the common barriers encountered by practitioners in delivering treatments in local contexts and highlights the role of external safety and stability and social support in providing a vehicle for change and a basis for overcoming the psychological handicaps reinforced by repeated and multiple traumas and chronic neglect.
- Full Text:
- Date Issued: 2012
Treatment of post traumatic stress disorder following an armed robbery : a case study testing the transportability of trauma-focused cognitive-behavioural therapy to urban Africans
- Drake, B, Edwards, David J A
- Authors: Drake, B , Edwards, David J A
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6225 , http://hdl.handle.net/10962/d1007775
- Description: John, an urban African male who developed post traumatic stress disorder (PTSD) following an armed robbery at the petrol station where he worked, was treated with 12 sessions of Trauma-focused cognitive behaviour therapy. Intervention involved a combination of psycho-education, prolonged imaginal exposure, cognitive restructuring and behavioural assignments. This article is a systematic case study of his treatment which included a comprehensive narrative and tracking of progress by means of the Post traumatic Diagnostic Scale. John responded well to the treatment, finding it acceptable and credible and remained free of PTSD symptoms at 15 months follow up. It is argued, based on the principles of Elliott’s Hermeneutic Single Case Efficacy Design, that there is evidence from within the narrative that it was the treatment that led to remission of symptoms. This case study demonstrates the cognitive, emotional and behavioural processes underlying John’s PTSD, which fits with those extensively described in the research literature, and that this evidence-based treatment developed in a westernised context is transportable to work with urban Africans.
- Full Text:
- Date Issued: 2012
- Authors: Drake, B , Edwards, David J A
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6225 , http://hdl.handle.net/10962/d1007775
- Description: John, an urban African male who developed post traumatic stress disorder (PTSD) following an armed robbery at the petrol station where he worked, was treated with 12 sessions of Trauma-focused cognitive behaviour therapy. Intervention involved a combination of psycho-education, prolonged imaginal exposure, cognitive restructuring and behavioural assignments. This article is a systematic case study of his treatment which included a comprehensive narrative and tracking of progress by means of the Post traumatic Diagnostic Scale. John responded well to the treatment, finding it acceptable and credible and remained free of PTSD symptoms at 15 months follow up. It is argued, based on the principles of Elliott’s Hermeneutic Single Case Efficacy Design, that there is evidence from within the narrative that it was the treatment that led to remission of symptoms. This case study demonstrates the cognitive, emotional and behavioural processes underlying John’s PTSD, which fits with those extensively described in the research literature, and that this evidence-based treatment developed in a westernised context is transportable to work with urban Africans.
- Full Text:
- Date Issued: 2012
Western alumnae influencing the world
- Authors: Steyaert, Marcia
- Date: 2012
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7168 , http://hdl.handle.net/10962/d1006069 , Nyokong, Tebello
- Description: In September 2011, IT News Africa, named two Western alumnae, Uche Eze, HBA'06, and Tebello Nyokong, PhD1987 (Chemistry) in their list of top 10 most influential women in science and technology in Africa. Nyokong is a professor of medicinal chemistry and nanotechnology at Rhodes University and is recognized as one of the top three publishing scientists in South Africa.
- Full Text:
- Date Issued: 2012
- Authors: Steyaert, Marcia
- Date: 2012
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7168 , http://hdl.handle.net/10962/d1006069 , Nyokong, Tebello
- Description: In September 2011, IT News Africa, named two Western alumnae, Uche Eze, HBA'06, and Tebello Nyokong, PhD1987 (Chemistry) in their list of top 10 most influential women in science and technology in Africa. Nyokong is a professor of medicinal chemistry and nanotechnology at Rhodes University and is recognized as one of the top three publishing scientists in South Africa.
- Full Text:
- Date Issued: 2012
The Educational Journal
- Date: 2011-09
- Subjects: Education – South Africa , South Africa – Economic conditions , South Africa – Social conditions
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/41687 , vital:36555 , Bulk File 7
- Description: The Educational Journal was the official organ of the Teachers' League of South Africa and focussed on education within the context of a racialized South Africa. From the 2000s, the journal was published by the National Union of Public Service and Allied Workers (NUPSAW), a trade union formed in August 1998 from the amalgamation of militant and moderate trade unions and also operated in the education sphere.
- Full Text: false
- Date Issued: 2011-09
- Date: 2011-09
- Subjects: Education – South Africa , South Africa – Economic conditions , South Africa – Social conditions
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/41687 , vital:36555 , Bulk File 7
- Description: The Educational Journal was the official organ of the Teachers' League of South Africa and focussed on education within the context of a racialized South Africa. From the 2000s, the journal was published by the National Union of Public Service and Allied Workers (NUPSAW), a trade union formed in August 1998 from the amalgamation of militant and moderate trade unions and also operated in the education sphere.
- Full Text: false
- Date Issued: 2011-09
APDUSA Views
- Date: 2011-06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10948/33486 , vital:32879 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 2011-06
- Date: 2011-06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10948/33486 , vital:32879 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 2011-06
APDUSA Views
- Date: 2011- 06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33536 , vital:32884 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 2011- 06
- Date: 2011- 06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33536 , vital:32884 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 2011- 06
3000 miles from home: a new Gastrosericus baobabicus Pulawski, 1995 (Hymenoptera, Larridae) distribution record highlights that the Sahel has a distinct entomofaunal signature
- Clitheroe, C-L, Villet, Martin H
- Authors: Clitheroe, C-L , Villet, Martin H
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6846 , http://hdl.handle.net/10962/d1011099
- Description: [from introduction] On October 30, 1953, an unidentified female wasp (Fig. 1) was collected from ‘Belet Uen, Somaliland’ (= Beledweyne, 4°44’N 45°12’E), situated in the valley of the Shebelle River, HiraanProvince,Somalia. It was deposited in the aculeate Hymenoptera collection of the Albany Museum, Grahamstown by D. Greathead prior to 1968. Apart from the words ‘Somaliland’ and ‘Desert Locust Survey’ the label is handwritten and the collector’snameis not recorded. Greathead’s sister, S. Gess (Albany Museum), deciphered the label and stated that he had worked for the Desert Locust Survey, investigating the natural enemies of locusts and had been in Somalia (then Somaliland) at that time (Murphy & Cock 2007). The specimen was sent in 2004 by F. Gess to W. Pulawski, who determined it as Gastrosericus baobabicus Pulawski, 1995. Gastrosericus species prey on spiders and a variety of small insects (Pulawski 1995), including Orthoptera (Krombein & Pulawski 1986), so it is likely that Greathead collected the specimen in connection with his interest in the insect enemies of Acridoidea (Orthoptera) (Greathead 1962).
- Full Text:
- Date Issued: 2011
- Authors: Clitheroe, C-L , Villet, Martin H
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6846 , http://hdl.handle.net/10962/d1011099
- Description: [from introduction] On October 30, 1953, an unidentified female wasp (Fig. 1) was collected from ‘Belet Uen, Somaliland’ (= Beledweyne, 4°44’N 45°12’E), situated in the valley of the Shebelle River, HiraanProvince,Somalia. It was deposited in the aculeate Hymenoptera collection of the Albany Museum, Grahamstown by D. Greathead prior to 1968. Apart from the words ‘Somaliland’ and ‘Desert Locust Survey’ the label is handwritten and the collector’snameis not recorded. Greathead’s sister, S. Gess (Albany Museum), deciphered the label and stated that he had worked for the Desert Locust Survey, investigating the natural enemies of locusts and had been in Somalia (then Somaliland) at that time (Murphy & Cock 2007). The specimen was sent in 2004 by F. Gess to W. Pulawski, who determined it as Gastrosericus baobabicus Pulawski, 1995. Gastrosericus species prey on spiders and a variety of small insects (Pulawski 1995), including Orthoptera (Krombein & Pulawski 1986), so it is likely that Greathead collected the specimen in connection with his interest in the insect enemies of Acridoidea (Orthoptera) (Greathead 1962).
- Full Text:
- Date Issued: 2011
Above ground woody community attributes, biomass and carbon stocks along a rainfall gradient in the savannas of the central lowveld, South Africa
- Shackleton, Charlie M, Scholes, Robert J
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6658 , http://hdl.handle.net/10962/d1007079
- Description: Enumeration of carbon stocks at benchmark sites is a necessary activity in assessing the potential carbon sequestration and possible generation of credits through restoration of intensively impacted sites. However, there is a lack of empirical studies throughout much of the savannas of sub-Saharan Africa, including South Africa. We report an estimation of species specific and site biomass and carbon stocks, and general vegetation structural attributes from three protected areas along a rainfall gradient in the central lowveld, South Africa. Estimates of biomass and carbon stocks were effected through destructive sampling to establish locally derived allometric equations. There was a gradient of increasing woody density, height of the canopy, number of species, density of regenerative stems and a greater proportion of stems in small size classes from the arid locality to the mesic locality, with the semi-arid locality being intermediate. The proportion of spinescent species decreased with increasing rainfall. The mesic locality was significantly more woody than either the arid or semi-arid sites, having double the biomass, four times the density and 40% higher basal area. Above ground carbon pools were also higher; carbon stocks were approximately 9 t/ha for the arid and semi-arid sites and 18 t/ha for the mesic site.
- Full Text:
- Date Issued: 2011
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6658 , http://hdl.handle.net/10962/d1007079
- Description: Enumeration of carbon stocks at benchmark sites is a necessary activity in assessing the potential carbon sequestration and possible generation of credits through restoration of intensively impacted sites. However, there is a lack of empirical studies throughout much of the savannas of sub-Saharan Africa, including South Africa. We report an estimation of species specific and site biomass and carbon stocks, and general vegetation structural attributes from three protected areas along a rainfall gradient in the central lowveld, South Africa. Estimates of biomass and carbon stocks were effected through destructive sampling to establish locally derived allometric equations. There was a gradient of increasing woody density, height of the canopy, number of species, density of regenerative stems and a greater proportion of stems in small size classes from the arid locality to the mesic locality, with the semi-arid locality being intermediate. The proportion of spinescent species decreased with increasing rainfall. The mesic locality was significantly more woody than either the arid or semi-arid sites, having double the biomass, four times the density and 40% higher basal area. Above ground carbon pools were also higher; carbon stocks were approximately 9 t/ha for the arid and semi-arid sites and 18 t/ha for the mesic site.
- Full Text:
- Date Issued: 2011
Culture as a discursive resource opposing legal abortion
- Macleod, Catriona I, Sigcau, Nomakhosi, Luwaca, Pumeza
- Authors: Macleod, Catriona I , Sigcau, Nomakhosi , Luwaca, Pumeza
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6293 , http://hdl.handle.net/10962/d1014721 , http://dx.doi.org/10.1080/09581596.2010.492211
- Description: The notion of ‘culture’ features in the abortion literature to explicate, first, contestation of the meaning of abortion (as in the ‘culture wars’ about abortion), second, the normalisation of abortion in certain countries (as in ‘abortion culture’), third, the response of women to abortion within a particular social milieu and fourth, cross-cultural variability in attitudes towards and experiences of abortion. What is missing is an exploration of how ‘culture’ may be deployed as a discursive resource to oppose legal abortion. In this article, we report on a study conducted in a rural area of South Africa. We conducted focus group discussions utilising hypothetical vignettes to stimulate talk. Although, inconsistencies were evident in participants’ talk, in the context of cultural discussions, abortion was constructed as killing and inevitably destructive of cultural values and traditions. Abortion was equated with colonialist interventions and as something that should be opposed in the preservation of culture. Furthermore, cultural opposition to abortion was rooted in fears around the breakdown of gendered and generational power relations. Examples of how culture may be used in everyday interactions to induce shame and negative experiences are also discussed.
- Full Text:
- Date Issued: 2011
- Authors: Macleod, Catriona I , Sigcau, Nomakhosi , Luwaca, Pumeza
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6293 , http://hdl.handle.net/10962/d1014721 , http://dx.doi.org/10.1080/09581596.2010.492211
- Description: The notion of ‘culture’ features in the abortion literature to explicate, first, contestation of the meaning of abortion (as in the ‘culture wars’ about abortion), second, the normalisation of abortion in certain countries (as in ‘abortion culture’), third, the response of women to abortion within a particular social milieu and fourth, cross-cultural variability in attitudes towards and experiences of abortion. What is missing is an exploration of how ‘culture’ may be deployed as a discursive resource to oppose legal abortion. In this article, we report on a study conducted in a rural area of South Africa. We conducted focus group discussions utilising hypothetical vignettes to stimulate talk. Although, inconsistencies were evident in participants’ talk, in the context of cultural discussions, abortion was constructed as killing and inevitably destructive of cultural values and traditions. Abortion was equated with colonialist interventions and as something that should be opposed in the preservation of culture. Furthermore, cultural opposition to abortion was rooted in fears around the breakdown of gendered and generational power relations. Examples of how culture may be used in everyday interactions to induce shame and negative experiences are also discussed.
- Full Text:
- Date Issued: 2011