Replication of maximal work output levels in able-bodied workers and candidates for disability assessments: benchmark data and guidelines
- Charteris, J, James, Jonathan P
- Authors: Charteris, J , James, Jonathan P
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6752 , http://hdl.handle.net/10962/d1009332
- Description: [From the introduction]: Injured-at-work employees, when the impairments are musculo-skeletal, and the injury beyond dispute, may be faced with formal rehabilitation or informal recuperation, sometimes preceded by surgical intervention, or they may be exposed to a process of application for compensation, part of which may involve medico-legal assessments. Questions that need to be addressed somewhere in this process will determine whether the impairment is of short duration, chronic or irreparable, and will involve determination also of the severity of the impairment and the issue of the workers’ capacity to return to the former occupation versus the need to find a new employment niche commensurate with the disabled workers’ capabilities. Inevitably in this process, if it is formal, someone will need to assess the musculoskeletal strength of the injured employee and make pronouncements as to physical capacity and work-readiness. In the absence of clinical ergonomists in South Africa this task falls to a variety of professionals, some well and others poorly trained to make these determinations. Most often the assessments of work-readiness are crude, amounting to little more than unsubstantiable value judgements of supervisors or health professionals not well versed in human performance capabilities. Increasingly however, better qualified professionals are making themselves available to meet the growing demands of a more employee-centred working ethos in this country. This paper is targeted at those medical, paramedical and ergonomics professionals who already have the facilities and the expertise to make use of the technique outlined herein, to further enhance their already sound means of job-related disability assessment.
- Full Text:
- Date Issued: 2000
- Authors: Charteris, J , James, Jonathan P
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6752 , http://hdl.handle.net/10962/d1009332
- Description: [From the introduction]: Injured-at-work employees, when the impairments are musculo-skeletal, and the injury beyond dispute, may be faced with formal rehabilitation or informal recuperation, sometimes preceded by surgical intervention, or they may be exposed to a process of application for compensation, part of which may involve medico-legal assessments. Questions that need to be addressed somewhere in this process will determine whether the impairment is of short duration, chronic or irreparable, and will involve determination also of the severity of the impairment and the issue of the workers’ capacity to return to the former occupation versus the need to find a new employment niche commensurate with the disabled workers’ capabilities. Inevitably in this process, if it is formal, someone will need to assess the musculoskeletal strength of the injured employee and make pronouncements as to physical capacity and work-readiness. In the absence of clinical ergonomists in South Africa this task falls to a variety of professionals, some well and others poorly trained to make these determinations. Most often the assessments of work-readiness are crude, amounting to little more than unsubstantiable value judgements of supervisors or health professionals not well versed in human performance capabilities. Increasingly however, better qualified professionals are making themselves available to meet the growing demands of a more employee-centred working ethos in this country. This paper is targeted at those medical, paramedical and ergonomics professionals who already have the facilities and the expertise to make use of the technique outlined herein, to further enhance their already sound means of job-related disability assessment.
- Full Text:
- Date Issued: 2000
Load stress; carrier strain: implications for military and receational backpacking
- Authors: Charteris, J
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6754 , http://hdl.handle.net/10962/d1009456
- Description: This paper reviews a growing literature on the stress of backpacking, particularly in military situations. Conceptual issues are raised and the implications for recreational backpackers are addressed. Under moderate to fairly heavy loading the energy cost, per kg total load carried, per hour, relates almost linearly to walking speed. Empirical data from studies in this unit are presented as benchmark indicators for use by recreational backpackers.
- Full Text:
- Date Issued: 2007
- Authors: Charteris, J
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6754 , http://hdl.handle.net/10962/d1009456
- Description: This paper reviews a growing literature on the stress of backpacking, particularly in military situations. Conceptual issues are raised and the implications for recreational backpackers are addressed. Under moderate to fairly heavy loading the energy cost, per kg total load carried, per hour, relates almost linearly to walking speed. Empirical data from studies in this unit are presented as benchmark indicators for use by recreational backpackers.
- Full Text:
- Date Issued: 2007
Sperm morphology in four species of African platypleurine cicadas (Hemiptera: Cicadomorpha: Cicadidae)
- Chawanji, A S, Hodgson, Alan N, Villet, Martin H
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6917 , http://hdl.handle.net/10962/d1011880
- Description: Mature spermatozoa from four species of platypleurine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis and P. hirtipennis) were examined by light and electron microscopy. The filiform sperm have a similar ultrastructure in all species but notable variations were found in sperm dimensions. All species produce more than one discrete length of nucleated, motile sperm, a form of polymorphism termed polymegaly. Polymegaly is expressed in two ways: sperm have bi- or trimodal head and tail lengths. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming a spermatodesm. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with an electron-lucent central medulla and a denser cortex. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the centriolar adjunct. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely affiliated.
- Full Text:
- Date Issued: 2005
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6917 , http://hdl.handle.net/10962/d1011880
- Description: Mature spermatozoa from four species of platypleurine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis and P. hirtipennis) were examined by light and electron microscopy. The filiform sperm have a similar ultrastructure in all species but notable variations were found in sperm dimensions. All species produce more than one discrete length of nucleated, motile sperm, a form of polymorphism termed polymegaly. Polymegaly is expressed in two ways: sperm have bi- or trimodal head and tail lengths. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming a spermatodesm. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with an electron-lucent central medulla and a denser cortex. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the centriolar adjunct. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely affiliated.
- Full Text:
- Date Issued: 2005
Sperm morphology in five species of cicadettine cicadas (Hemiptera: Cicadomorpha: Cicadidae)
- Chawanji, A S, Hodgson, Alan N, Villet, Martin H
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6930 , http://hdl.handle.net/10962/d1011948
- Description: Mature spermatozoa from five species of cicadas of the subfamily Cicadettinae (Quintilia wealei, Melampsalta leucoptera, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) were examined by light and electron microscopy. In each species sperm are elongate, aggregated into organized bundles with their heads embedded in a homogenous matrix to form spermatodesmata, and exhibit polymegaly. The head of the sperm consist of an anteriorly positioned conical acrosome that has a tubular substructure and a deep, posterior invagination that forms the subacrosomal space (eccentrically positioned anteriorly). The acrosome is flattened anteriorly; posteriorly it extends along either side of the nucleus as two tubular processes that gradually decrease in diameter. The filiform nucleus tapers anteriorly and intrudes into the subscrosomal space. Posteriorly the nucleus has a lateral invagination that houses material of the so-called centriolar adjunct. Posterior to the centriolar adjuct and the nucleus are two crystalline mitochondrial derivatives and a centriole, respectively, the latter giving rise to the axoneme, which has a 9 + 9 + 2 arrangement of microtubules. In these respects the sperm are similar to those of platypleurine cicadas. However, some features seem unique to cicadettines, including the structural organization of an enlarged centriolar adjunct and the dimensions of the tails. The enlarged centriolar adjunct has a lamella-like substructure and can be considered a synapomorphic character in the Cicadettinae. It is, therefore, potentially useful in the separation of this subfamily from the Cicadinae. In addition, the great length of the sperm nucleus of long-headed sperm in M. matoposa could be a synapomorphy of this genus and related taphurine and cicadettine species.
- Full Text:
- Date Issued: 2006
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6930 , http://hdl.handle.net/10962/d1011948
- Description: Mature spermatozoa from five species of cicadas of the subfamily Cicadettinae (Quintilia wealei, Melampsalta leucoptera, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) were examined by light and electron microscopy. In each species sperm are elongate, aggregated into organized bundles with their heads embedded in a homogenous matrix to form spermatodesmata, and exhibit polymegaly. The head of the sperm consist of an anteriorly positioned conical acrosome that has a tubular substructure and a deep, posterior invagination that forms the subacrosomal space (eccentrically positioned anteriorly). The acrosome is flattened anteriorly; posteriorly it extends along either side of the nucleus as two tubular processes that gradually decrease in diameter. The filiform nucleus tapers anteriorly and intrudes into the subscrosomal space. Posteriorly the nucleus has a lateral invagination that houses material of the so-called centriolar adjunct. Posterior to the centriolar adjuct and the nucleus are two crystalline mitochondrial derivatives and a centriole, respectively, the latter giving rise to the axoneme, which has a 9 + 9 + 2 arrangement of microtubules. In these respects the sperm are similar to those of platypleurine cicadas. However, some features seem unique to cicadettines, including the structural organization of an enlarged centriolar adjunct and the dimensions of the tails. The enlarged centriolar adjunct has a lamella-like substructure and can be considered a synapomorphic character in the Cicadettinae. It is, therefore, potentially useful in the separation of this subfamily from the Cicadinae. In addition, the great length of the sperm nucleus of long-headed sperm in M. matoposa could be a synapomorphy of this genus and related taphurine and cicadettine species.
- Full Text:
- Date Issued: 2006
Spermiogenesis in three species of cicadas (Hemiptera: Cicadidae)
- Chawanji, A S, Hodgson, Alan N, Villet, Martin H, Sanborn, Allen F, Phillips, P K
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H , Sanborn, Allen F , Phillips, P K
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6865 , http://hdl.handle.net/10962/d1011207
- Description: Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero-lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante-acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.
- Full Text:
- Date Issued: 2007
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H , Sanborn, Allen F , Phillips, P K
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6865 , http://hdl.handle.net/10962/d1011207
- Description: Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero-lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante-acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.
- Full Text:
- Date Issued: 2007
Corrole–BODIPY conjugates: enhancing the fluorescence and phosphorescence of the corrole complex via efficient through bond energy transfer
- Chen, Wei, Zhang, Jianfeng, Mack, John, Kubheka, Gugu Patience, Nyokong, Tebello, Shen, Zhen, Wei Chen
- Authors: Chen, Wei , Zhang, Jianfeng , Mack, John , Kubheka, Gugu Patience , Nyokong, Tebello , Shen, Zhen , Wei Chen
- Date: 2015-06-08
- Subjects: RSC Advances (2015), 5, 50962-50967, doi:10.1039/C5RA07250F
- Language: English
- Type: Article
- Identifier: vital:7268 , http://hdl.handle.net/10962/d1020277
- Description: New corrole–BODIPY conjugates have been synthesized in high yield under mild conditions. Upon excitation at the absorption maximum of the BODIPY antenna chromophore, the fluorescence intensity of the free base corrole–BODIPY conjugate increases by ca. 300%, and significant phosphorescence intensity is observed for the iridium(III) complex of the conjugate, while almost no phosphorescence is observed for the parent iridium(III) corrole, due to through-bond energy transfer from the BODIPY antenna-chromophore to the corrole core. , Original publication is available at http://dx.doi.org/10.1039/c5ra07250f , Arbortext Advanced Print Publisher 9.1.510/W Unicode , Acrobat Distiller 8.1.0 (Windows); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
- Full Text:
- Authors: Chen, Wei , Zhang, Jianfeng , Mack, John , Kubheka, Gugu Patience , Nyokong, Tebello , Shen, Zhen , Wei Chen
- Date: 2015-06-08
- Subjects: RSC Advances (2015), 5, 50962-50967, doi:10.1039/C5RA07250F
- Language: English
- Type: Article
- Identifier: vital:7268 , http://hdl.handle.net/10962/d1020277
- Description: New corrole–BODIPY conjugates have been synthesized in high yield under mild conditions. Upon excitation at the absorption maximum of the BODIPY antenna chromophore, the fluorescence intensity of the free base corrole–BODIPY conjugate increases by ca. 300%, and significant phosphorescence intensity is observed for the iridium(III) complex of the conjugate, while almost no phosphorescence is observed for the parent iridium(III) corrole, due to through-bond energy transfer from the BODIPY antenna-chromophore to the corrole core. , Original publication is available at http://dx.doi.org/10.1039/c5ra07250f , Arbortext Advanced Print Publisher 9.1.510/W Unicode , Acrobat Distiller 8.1.0 (Windows); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
- Full Text:
Variability in pH, fCO2, oxygen and flux of CO2 in the surface water along a transect in the Atlantic sector of the Southern Ocean
- Chierici, M, Fransson, A, Turner, D R, Pakhomov, E A, Froneman, Pierre William
- Authors: Chierici, M , Fransson, A , Turner, D R , Pakhomov, E A , Froneman, Pierre William
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6847 , http://hdl.handle.net/10962/d1011105
- Description: Underway sampling and measurements of pH, fCO2, oxygen and Chlorophyll a (Chl a) were performed in the surface waters from Cape Town (South Africa) to Queen Maud Land (Antarctica) in the Atlantic sector of the Southern Ocean during the austral summer 1997/1998. From direct measurements of these parameters and from calculated fCO2 the oceanic carbon dioxide system was studied and related to hydrological and biological parameters. fCO2 was in general undersaturated relative to the atmosphere and showed a large variability with values ranging from 313 to 377 μatm with a mean value of 346±13 μatm. The undersaturation was more pronounced in areas associated with fronts where high Chl a and high pH in situ values were observed. Using shipboard wind speed data, estimates of the CO2 flux were made along the transect and during three mesoscale surveys on the northward return transect in the area of the Spring Ice Edge (SIE), the Winter Ice Edge (WIE) and in the Antarctic Polar Front (APF). The undersaturation observed during the transect caused the ocean to act as a sink for CO2 with a mean sea–air flux for the entire transect of −3±5 mmol m−2 d−1 with a large variability between −20 mmol m−2 d−1 (oceanic uptake) to 1.3 mmol m−2 d−1 (oceanic source). The lowest fCO2 values (largest oceanic uptake of CO2) were found at the southern boundary of the APF at 53°S, which coincided with a supersaturation in oxygen and high pH values. Oxygen concentrations were measured from 50°S to 63°S and varied between 324 and 359 μmol kg−1 with a mean value of 347±9 μmol kg−1. In general only small deviations from equilibrium oxygen saturation were observed (mean value=99±2%). However, in the SIE oxygen was clearly undersaturated, probably an effect of upwelling of oxygen poor deep water which had not yet been compensated for by biological production. Three weeks later, the ice edge had retreated in the SIE region and the Chl a concentration had increased three-fold, suggesting the start of a phytoplankton bloom. This was also seen in the oxygen concentration which had increased and showed supersaturation. This coincided with an increased oceanic uptake of CO2 in the SIE during the mesoscale survey.
- Full Text:
- Date Issued: 2004
- Authors: Chierici, M , Fransson, A , Turner, D R , Pakhomov, E A , Froneman, Pierre William
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6847 , http://hdl.handle.net/10962/d1011105
- Description: Underway sampling and measurements of pH, fCO2, oxygen and Chlorophyll a (Chl a) were performed in the surface waters from Cape Town (South Africa) to Queen Maud Land (Antarctica) in the Atlantic sector of the Southern Ocean during the austral summer 1997/1998. From direct measurements of these parameters and from calculated fCO2 the oceanic carbon dioxide system was studied and related to hydrological and biological parameters. fCO2 was in general undersaturated relative to the atmosphere and showed a large variability with values ranging from 313 to 377 μatm with a mean value of 346±13 μatm. The undersaturation was more pronounced in areas associated with fronts where high Chl a and high pH in situ values were observed. Using shipboard wind speed data, estimates of the CO2 flux were made along the transect and during three mesoscale surveys on the northward return transect in the area of the Spring Ice Edge (SIE), the Winter Ice Edge (WIE) and in the Antarctic Polar Front (APF). The undersaturation observed during the transect caused the ocean to act as a sink for CO2 with a mean sea–air flux for the entire transect of −3±5 mmol m−2 d−1 with a large variability between −20 mmol m−2 d−1 (oceanic uptake) to 1.3 mmol m−2 d−1 (oceanic source). The lowest fCO2 values (largest oceanic uptake of CO2) were found at the southern boundary of the APF at 53°S, which coincided with a supersaturation in oxygen and high pH values. Oxygen concentrations were measured from 50°S to 63°S and varied between 324 and 359 μmol kg−1 with a mean value of 347±9 μmol kg−1. In general only small deviations from equilibrium oxygen saturation were observed (mean value=99±2%). However, in the SIE oxygen was clearly undersaturated, probably an effect of upwelling of oxygen poor deep water which had not yet been compensated for by biological production. Three weeks later, the ice edge had retreated in the SIE region and the Chl a concentration had increased three-fold, suggesting the start of a phytoplankton bloom. This was also seen in the oxygen concentration which had increased and showed supersaturation. This coincided with an increased oceanic uptake of CO2 in the SIE during the mesoscale survey.
- Full Text:
- Date Issued: 2004
Do environmental factors influence the movement of estuarine fish? A case study using acoustic telemetry
- Childs, Amber-Robyn, Cowley, Paul D, Næsje, T F, Booth, Anthony J, Thorstad, Eva B, Økland, F
- Authors: Childs, Amber-Robyn , Cowley, Paul D , Næsje, T F , Booth, Anthony J , Thorstad, Eva B , Økland, F
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6772 , http://hdl.handle.net/10962/d1008070
- Description: Telemetry methods were used to investigate the influence of selected environmental variables on the position and movement of an estuarine-dependent haemulid, the spotted grunter Pomadasys commersonnii (Lacepède 1801), in the Great Fish Estuary, South Africa. Forty individuals (263–698 mm TL) were surgically implanted with acoustic coded transmitters and manually tracked during two periods (7 February to 24 March 2003; n = 20 and 29 September to 15 November 2003; n = 20). Real-time data revealed that spotted grunter are euryhaline (0–37) and are able to tolerate large variations in turbidity (4–356 FTU) and temperature (16–30 °C). However, the fish altered their position in response to large fluctuations in salinity, temperature and turbidity, which are characteristic of tidal estuarine environments. Furthermore, tidal phase had a strong influence on the position of spotted grunter in the estuary.
- Full Text:
- Date Issued: 2008
- Authors: Childs, Amber-Robyn , Cowley, Paul D , Næsje, T F , Booth, Anthony J , Thorstad, Eva B , Økland, F
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6772 , http://hdl.handle.net/10962/d1008070
- Description: Telemetry methods were used to investigate the influence of selected environmental variables on the position and movement of an estuarine-dependent haemulid, the spotted grunter Pomadasys commersonnii (Lacepède 1801), in the Great Fish Estuary, South Africa. Forty individuals (263–698 mm TL) were surgically implanted with acoustic coded transmitters and manually tracked during two periods (7 February to 24 March 2003; n = 20 and 29 September to 15 November 2003; n = 20). Real-time data revealed that spotted grunter are euryhaline (0–37) and are able to tolerate large variations in turbidity (4–356 FTU) and temperature (16–30 °C). However, the fish altered their position in response to large fluctuations in salinity, temperature and turbidity, which are characteristic of tidal estuarine environments. Furthermore, tidal phase had a strong influence on the position of spotted grunter in the estuary.
- Full Text:
- Date Issued: 2008
Concerning secondary thermoluminescence peaks in α-Al_2_O_3_:C
- Authors: Chithambo, Makaiko L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6793 , http://hdl.handle.net/10962/d1003823
- Description: Thermoluminescence characteristics of two subsidiary glow peaks, one below 100°C and the other above 300°C, have been studied for measurements between 30°C and 500°C in α-Al_2_O_3_:C. The thermoluminescence intensity of the lower temperature peak decreased with storage with a half-life of about 150 s. In contrast, the intensity of the higher temperature peak increased with storage towards some maximum. The peak-temperature of each of the secondary glow peaks was essentially constant with dose, whereas that of the main peak decreased with irradiation. The dose response for the three peaks was similar except for sublinear growth in the higher temperature peak at low dose values. These effects are discussed in terms of changes in the concentration of F+ luminescence precursors brought about by competitive electron retrapping at deep electron-traps or hole-traps. This work refines the physics and application of α-Al_2_O_3_:C luminescence in radiation dosimetry.
- Full Text:
- Date Issued: 2004
- Authors: Chithambo, Makaiko L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6793 , http://hdl.handle.net/10962/d1003823
- Description: Thermoluminescence characteristics of two subsidiary glow peaks, one below 100°C and the other above 300°C, have been studied for measurements between 30°C and 500°C in α-Al_2_O_3_:C. The thermoluminescence intensity of the lower temperature peak decreased with storage with a half-life of about 150 s. In contrast, the intensity of the higher temperature peak increased with storage towards some maximum. The peak-temperature of each of the secondary glow peaks was essentially constant with dose, whereas that of the main peak decreased with irradiation. The dose response for the three peaks was similar except for sublinear growth in the higher temperature peak at low dose values. These effects are discussed in terms of changes in the concentration of F+ luminescence precursors brought about by competitive electron retrapping at deep electron-traps or hole-traps. This work refines the physics and application of α-Al_2_O_3_:C luminescence in radiation dosimetry.
- Full Text:
- Date Issued: 2004
On the correlation between annealing and variabilities in pulsed-luminescence from quartz
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6797 , http://hdl.handle.net/10962/d1003923
- Description: Properties of luminescence lifetimes in quartz related to annealing between 500 and 900ºC have been investigated. The luminescence was pulse-stimulated at 470 nm from sets of granular quartz annealed at 500, 600, 700, 800, and 900ºC. The lifetimes decrease with annealing temperature from about 42 to 33 µѕ when the annealing temperature is increased from 500 to 900ºC. Luminescence lifetimes are most sensitive to duration of annealing at 600ºC, decreasing from 40.2 ± 0.7 µѕ by as much as 7 µѕ when the duration of annealing is changed from 10 to 60 min. However, at 800–900ºC lifetimes are essentially independent of annealing temperature at about 33 µѕ. Increasing the exciting beta dose causes an increase in the lifetimes of the stimulated luminescence in the sample annealed at 800ºC but not in those annealed at either 500 or 600ºC. The temperature-resolved distribution of luminescence lifetimes is affected by thermal quenching of luminescence. These features may be accounted for with reference to two principal luminescence centres involved in the luminescence emission process.
- Full Text:
- Date Issued: 2006
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6797 , http://hdl.handle.net/10962/d1003923
- Description: Properties of luminescence lifetimes in quartz related to annealing between 500 and 900ºC have been investigated. The luminescence was pulse-stimulated at 470 nm from sets of granular quartz annealed at 500, 600, 700, 800, and 900ºC. The lifetimes decrease with annealing temperature from about 42 to 33 µѕ when the annealing temperature is increased from 500 to 900ºC. Luminescence lifetimes are most sensitive to duration of annealing at 600ºC, decreasing from 40.2 ± 0.7 µѕ by as much as 7 µѕ when the duration of annealing is changed from 10 to 60 min. However, at 800–900ºC lifetimes are essentially independent of annealing temperature at about 33 µѕ. Increasing the exciting beta dose causes an increase in the lifetimes of the stimulated luminescence in the sample annealed at 800ºC but not in those annealed at either 500 or 600ºC. The temperature-resolved distribution of luminescence lifetimes is affected by thermal quenching of luminescence. These features may be accounted for with reference to two principal luminescence centres involved in the luminescence emission process.
- Full Text:
- Date Issued: 2006
Luminescence lifetime components in quartz: influence of irradiation and annealing
- Chithambo, Makaiko L, Ogundare, F O
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6811 , http://hdl.handle.net/10962/d1004304
- Description: Pulsed optically stimulated luminescence measured from quartz under certain combinations of annealing and measurement temperature can be resolved into multiple lifetime components. We have studied the influence on these lifetime components of annealing temperature up to 900 °C, beta irradiation dose as high as 1700 Gy, and temperature of stimulation up to 200 °C. Although the time-resolved spectra from which the lifetimes are determined may be measured without heating between irradiation and measurement, a necessary protocol in steady-state optical stimulation applications, studies reported in this paper have been augmented with investigations on the effect of temperature and duration of preheating on the principal and secondary lifetimes. Luminescence spectra for measurements up to 200 Gy consist of a single lifetime but two components occur thereafter, both are independent of radiation dose. The principal lifetime of 35 μs is not affected by temperature of anneal whereas the secondary lifetime increases from 9 to 18 μs when the annealing temperature is changed from 600 to 900 °C. The dependence of both the principal and secondary luminescence lifetimes on measurement temperature can be explained by thermal quenching of the associated luminescence. However, the influence of irradiation, preheating, and annealing on the lifetimes can be explained with reference to an energy band scheme in which the primary mechanism in the processes leading up to luminescence emission is the change in concentration of holes at various luminescence centres caused by annealing.
- Full Text:
- Date Issued: 2009
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6811 , http://hdl.handle.net/10962/d1004304
- Description: Pulsed optically stimulated luminescence measured from quartz under certain combinations of annealing and measurement temperature can be resolved into multiple lifetime components. We have studied the influence on these lifetime components of annealing temperature up to 900 °C, beta irradiation dose as high as 1700 Gy, and temperature of stimulation up to 200 °C. Although the time-resolved spectra from which the lifetimes are determined may be measured without heating between irradiation and measurement, a necessary protocol in steady-state optical stimulation applications, studies reported in this paper have been augmented with investigations on the effect of temperature and duration of preheating on the principal and secondary lifetimes. Luminescence spectra for measurements up to 200 Gy consist of a single lifetime but two components occur thereafter, both are independent of radiation dose. The principal lifetime of 35 μs is not affected by temperature of anneal whereas the secondary lifetime increases from 9 to 18 μs when the annealing temperature is changed from 600 to 900 °C. The dependence of both the principal and secondary luminescence lifetimes on measurement temperature can be explained by thermal quenching of the associated luminescence. However, the influence of irradiation, preheating, and annealing on the lifetimes can be explained with reference to an energy band scheme in which the primary mechanism in the processes leading up to luminescence emission is the change in concentration of holes at various luminescence centres caused by annealing.
- Full Text:
- Date Issued: 2009
Comparison of maximal aerobic capacity during running and lifting activities : research article
- Christie, Candice J, Scott, Patricia A
- Authors: Christie, Candice J , Scott, Patricia A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6745 , http://hdl.handle.net/10962/d1009314
- Description: Acknowledging the specificity of assessing maximal output, the purpose of this paper was to compare the physiological and perceptual responses during a traditional running activity and the common industrial task of lifting; both were taken to maximal effort. The responses of eight male participants were measured during both physical activities separated by at least five days: i) a progressive speed protocol (PSP) involved running on a treadmill at increasing speeds, starting at 10 km.h[superscript -1] and increasing by 1 km.h[superscript -1] every minute until exhaustion; ii) a progressive frequency protocol (PFP) required participants to lift a load of 20% body mass at increasing lifting frequencies, starting at one lift every 10s and reducing the time between lifts by 1s every minute until exhaustion. Physiological responses were measured using a portable on-line system, the K4b[superscript 2] (Cosmed(r)). "Central" perceptual measures were obtained every minute using the rating of perceived exertion (RPE) scale. Results: Responses increased progressively with augmented exercise intensity in both protocols; however, oxygen consumption and peak oxygen values were both lower during the lifting protocol compared to the running protocol. In contrast to the oxygen uptake responses, peak RER values were significantly higher during lifting (mean of 1.32) than running (mean of 1.18), while maximal heart rate and perceptual responses revealed no significant difference between the two protocols. These findings caution against using the 'traditional' treadmill protocol to assess the aerobic capacity of manual labourers involved in lifting, as it is evident that the traditional lower body protocol will indicate a higher capacity than the maximum capacity of an upper body activity, which could lead to manual labourers being taxed beyond acceptable limits.
- Full Text:
- Date Issued: 2005
- Authors: Christie, Candice J , Scott, Patricia A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6745 , http://hdl.handle.net/10962/d1009314
- Description: Acknowledging the specificity of assessing maximal output, the purpose of this paper was to compare the physiological and perceptual responses during a traditional running activity and the common industrial task of lifting; both were taken to maximal effort. The responses of eight male participants were measured during both physical activities separated by at least five days: i) a progressive speed protocol (PSP) involved running on a treadmill at increasing speeds, starting at 10 km.h[superscript -1] and increasing by 1 km.h[superscript -1] every minute until exhaustion; ii) a progressive frequency protocol (PFP) required participants to lift a load of 20% body mass at increasing lifting frequencies, starting at one lift every 10s and reducing the time between lifts by 1s every minute until exhaustion. Physiological responses were measured using a portable on-line system, the K4b[superscript 2] (Cosmed(r)). "Central" perceptual measures were obtained every minute using the rating of perceived exertion (RPE) scale. Results: Responses increased progressively with augmented exercise intensity in both protocols; however, oxygen consumption and peak oxygen values were both lower during the lifting protocol compared to the running protocol. In contrast to the oxygen uptake responses, peak RER values were significantly higher during lifting (mean of 1.32) than running (mean of 1.18), while maximal heart rate and perceptual responses revealed no significant difference between the two protocols. These findings caution against using the 'traditional' treadmill protocol to assess the aerobic capacity of manual labourers involved in lifting, as it is evident that the traditional lower body protocol will indicate a higher capacity than the maximum capacity of an upper body activity, which could lead to manual labourers being taxed beyond acceptable limits.
- Full Text:
- Date Issued: 2005
Consideration of the effect of nutritional status and disease patterns on the work output amongst Black South African workers involved in manual materials handling (MMH) tasks
- Authors: Christie, Candice J
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6746 , http://hdl.handle.net/10962/d1009315
- Description: The prevalence of malnutrition amongst low-income earning South Africans has been well documented and is reported to be particularly high amongst Black South African males. This, combined with poor living conditions associated with their poor socio-economic status, results in an increased prevalence of infectious diseases amongst this sector of the population. Additionally, Black South African males are most often employed by companies requiring them to carry out heavy manual materials handling tasks. It would appear that limited research has focused on the relationship between inadequate dietary intake combined with poor health status and the impact this may have on the performance of manual workers. Energy intake is in all probability considerably less than energy expenditure.
- Full Text:
- Date Issued: 2001
- Authors: Christie, Candice J
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6746 , http://hdl.handle.net/10962/d1009315
- Description: The prevalence of malnutrition amongst low-income earning South Africans has been well documented and is reported to be particularly high amongst Black South African males. This, combined with poor living conditions associated with their poor socio-economic status, results in an increased prevalence of infectious diseases amongst this sector of the population. Additionally, Black South African males are most often employed by companies requiring them to carry out heavy manual materials handling tasks. It would appear that limited research has focused on the relationship between inadequate dietary intake combined with poor health status and the impact this may have on the performance of manual workers. Energy intake is in all probability considerably less than energy expenditure.
- Full Text:
- Date Issued: 2001
Relationship between energy intake and expenditure during harvesting tasks
- Authors: Christie, Candice J
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6758 , http://hdl.handle.net/10962/d1009461
- Description: The objective of this study was to compare the energy demands of manual harvesting tasks with the associated energy intake of the workers’. Fifty eight workers (29 Chainsaw Operators and 29 Stackers) were assessed in South Africa prior to, and during a ‘normal’ working shift. Habitual dietary analyses showed that the workers were eating less than 56% of the recommended daily allowance and were thus arriving at work with reduced energy stores. Heart rate responses were measured continuously during work and energy expenditure was predicted from the heart rate/oxygen uptake relationship obtained at a post-work progressive step up test completed by each worker. The data indicated that the tasks placed ‘moderate-to-heavy’ demands on the workers resulting in a significant imbalance between the energy demands of the tasks and the associated energy intake of the workers. Energy deficits were in excess of 8 000 kJ and workers lost, on average, 2.8% body mass during work while felling and cross-cutting, and 3.6% during stacking.
- Full Text:
- Date Issued: 2008
- Authors: Christie, Candice J
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6758 , http://hdl.handle.net/10962/d1009461
- Description: The objective of this study was to compare the energy demands of manual harvesting tasks with the associated energy intake of the workers’. Fifty eight workers (29 Chainsaw Operators and 29 Stackers) were assessed in South Africa prior to, and during a ‘normal’ working shift. Habitual dietary analyses showed that the workers were eating less than 56% of the recommended daily allowance and were thus arriving at work with reduced energy stores. Heart rate responses were measured continuously during work and energy expenditure was predicted from the heart rate/oxygen uptake relationship obtained at a post-work progressive step up test completed by each worker. The data indicated that the tasks placed ‘moderate-to-heavy’ demands on the workers resulting in a significant imbalance between the energy demands of the tasks and the associated energy intake of the workers. Energy deficits were in excess of 8 000 kJ and workers lost, on average, 2.8% body mass during work while felling and cross-cutting, and 3.6% during stacking.
- Full Text:
- Date Issued: 2008
Enhancing military efficiency : a South African perspective
- Christie, Candice J, Todd, Andrew I
- Authors: Christie, Candice J , Todd, Andrew I
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6749 , http://hdl.handle.net/10962/d1009329
- Description: While extensive military research has been conducted in developed countries, very little work has been done on soldiers in industrially developing countries (IDCs). Although many aspects of marching are similar around the globe, the challenges facing soldiers in IDCs, and in particular South Africa, are unique. Since the 1990’s South Africa has seen a considerable shift in the morphological and cultural make-up of the South African National Defence Force (SANDF). The result is a mix of soldiers from a variety of ethnic backgrounds. Ethnic differences may ultimately impact performance particularly as research has postulated that Blacks and Whites may differ in body composition and body proportions. It is highly probable then that the universal recommendations of optimal marching speeds, load masses and gradients need to be modified to accommodate the diversity of soldiers which currently comprise the SANDF.
- Full Text:
- Date Issued: 2001
- Authors: Christie, Candice J , Todd, Andrew I
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6749 , http://hdl.handle.net/10962/d1009329
- Description: While extensive military research has been conducted in developed countries, very little work has been done on soldiers in industrially developing countries (IDCs). Although many aspects of marching are similar around the globe, the challenges facing soldiers in IDCs, and in particular South Africa, are unique. Since the 1990’s South Africa has seen a considerable shift in the morphological and cultural make-up of the South African National Defence Force (SANDF). The result is a mix of soldiers from a variety of ethnic backgrounds. Ethnic differences may ultimately impact performance particularly as research has postulated that Blacks and Whites may differ in body composition and body proportions. It is highly probable then that the universal recommendations of optimal marching speeds, load masses and gradients need to be modified to accommodate the diversity of soldiers which currently comprise the SANDF.
- Full Text:
- Date Issued: 2001
Pharmacotherapeutic interventions for bipolar disorder type II: addressing multiple symptoms and approaches with a particular emphasis on strategies in lower and middle-income countries
- Authors: Christoffel Grobler
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3829 , vital:43952
- Full Text:
- Authors: Christoffel Grobler
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3829 , vital:43952
- Full Text:
Pharmacotherapeutic interventions for bipolar disorder type II: addressing multiple symptoms and approaches with a particular emphasis on strategies in lower and middle-income countries
- Authors: Christoffel Grobler
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3872 , vital:43960
- Full Text:
- Authors: Christoffel Grobler
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3872 , vital:43960
- Full Text:
Does the growth of structure affect our dynamical models of the Universe? The averaging, backreaction, and fitting problems in cosmology
- Clarkson, C, Ellis, G, Larena, Julien, Umeh, O
- Authors: Clarkson, C , Ellis, G , Larena, Julien , Umeh, O
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6791 , http://hdl.handle.net/10962/d1006944
- Description: Structure occurs over a vast range of scales in the Universe. Our large-scale cosmological models are coarse-grained representations of what exists, which have much less structure than there really is. An important problem for cosmology is determining the influence the small-scale structure in the Universe has on its large-scale dynamics and observations. Is there a significant, general relativistic, backreaction effect from averaging over structure? One issue is whether the process of smoothing over structure can contribute to an acceleration term and so alter the apparent value of the cosmological constant. If this is not the case, are there other aspects of concordance cosmology that are affected by backreaction effects? Despite much progress, this 'averaging problem' is still unanswered, but it cannot be ignored in an era of precision cosmology, for instance it may affect aspects of baryon acoustic oscillation observations.
- Full Text:
- Date Issued: 2011
- Authors: Clarkson, C , Ellis, G , Larena, Julien , Umeh, O
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6791 , http://hdl.handle.net/10962/d1006944
- Description: Structure occurs over a vast range of scales in the Universe. Our large-scale cosmological models are coarse-grained representations of what exists, which have much less structure than there really is. An important problem for cosmology is determining the influence the small-scale structure in the Universe has on its large-scale dynamics and observations. Is there a significant, general relativistic, backreaction effect from averaging over structure? One issue is whether the process of smoothing over structure can contribute to an acceleration term and so alter the apparent value of the cosmological constant. If this is not the case, are there other aspects of concordance cosmology that are affected by backreaction effects? Despite much progress, this 'averaging problem' is still unanswered, but it cannot be ignored in an era of precision cosmology, for instance it may affect aspects of baryon acoustic oscillation observations.
- Full Text:
- Date Issued: 2011
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
Ellisras Longitudinal Study 2017: association of hypertension with increasing levels of adiposity in 10- to 14-year-old boys and girls in the Eastern Cape (ELS 31)
- CM Tata
- Authors: CM Tata
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/5128 , vital:44352
- Full Text:
- Authors: CM Tata
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/5128 , vital:44352
- Full Text: