Improved Automatic Face Segmentation and Recognition for Applications with Limited Training Data
- Authors: Bradshaw, Karen L , Brown, Dane L
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/460085 , vital:75891 , ISBN 9783319582740 , https://doi.org/10.1007/978-3-319-58274-0_33
- Description: This paper introduces varied pose angle, a new approach to improve face identification given large pose angles and limited training data. Face landmarks are extracted and used to normalize and segment the face. Our approach does not require face frontalization and achieves consistent results. Results are compared using frontal and non-frontal training images for Eigen and Fisher classification of various face pose angles. Fisher scales better with more training samples only with a high quality dataset. Our approach achieves promising results for three well-known face datasets.
- Full Text:
- Date Issued: 2017
One size does not fit all: critical insights for effective community-based resource management in Melanesia
- Authors: Aswani, Shankar , Albert, Simon , Love, Mark
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145392 , vital:38434 , DOI: 10.1016/j.marpol.2017.03.041
- Description: In recent years, Fiji's approach of combining traditional systems of community-based coastal management and modern management systems has become a successful blueprint for marine conservation, particularly the Locally Managed Marine Area (LMMA) network model. As a result of this success, conservation practitioners have imported the Fiji LMMA model to the Solomon Islands and in Vanuatu in hope of replicating the purported success attained in Fiji. This paper argues that because tenure systems and associated political systems in Fiji, the Solomon Islands, and Vanuatu are substantially different, one cannot simply extrapolate the more centralized tenurial and political Fiji model to the decentralized tenurial and politically eclectic Solomons and Vanuatu. This paper provides an analysis of some of the various approaches used in these countries to make a case for why socio-political diversity and historical particulars matter to resource management and conservation-in-practice (and for any development interventions).
- Full Text:
- Date Issued: 2017
Perceptions of Chinese and Tanzanian employees regarding intercultural collaboration
- Authors: Mayer, Claude-Hélène , Boness, Christian M , Louw, Lynette
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125542 , vital:35793 , https://doi.org/10.4102/sajhrm.v15i0.921
- Description: China’s impact and role in the development of countries in Africa, primarily through foreign direct investments and grants to governments, has increased in the past decade. For instance, the total value of trade between China and Africa was USD198.5 billion in 2012, increasing to USD385bn in 2015 (African Economic Outlook, 2014, p. 76). A growing number of Chinese private and governmental organisations are investing in southern Africa. In Tanzanian contexts, this leads to a close collaboration of Chinese and Tanzanian employees (African Economic Outlook, 2014). These collaborations in Chinese organisations in Tanzania lead to intercultural communication situations and to new intercultural experiences and perceptions.
- Full Text:
- Date Issued: 2017
Postcolonialism and psychology: Growing interest and promising potential
- Authors: Macleod, Catriona I , Bhatia, Sunil , Kessi, Shose
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/434332 , vital:73049 , ISBN 9781473925212 , https://uk.sagepub.com/en-gb/eur/the-sage-handbook-of-qualitative-research-in-psychology/book245472#description
- Description: In the first edition of this book published in 2008, we categorized postcolonial psychology as embryonic: at the time very few psychologists were using postcolonial theories and approaches to illuminate broadly psychological issues. Since then, there has been some growing interest, to which we refer below. Nevertheless, despite recent contributions to postcolonial psychology literature under the banner of critical psychology (Bhatia, 2014; Moane and Sonn, 2015; Painter, 2015; Teo, 2005) as well as a number of books tackling the psychological in relation to postcolonial theory in the last decade (Anderson et al., 2011; Bhatia, 2007; David, 2011; Good et al., 2008; Hook, 2012; Macleod, 2011; Moane, 2011), postcolonial psychology is far from being an established or significant sub-discipline of psychology. The growing interest and positive responses to some of the work (eg Parker, 2012) must, however, be seen as encouraging in demonstrating the promising potential of postcolonial approaches in psychology, particularly in the political and social conditions of the twenty-first century. By way of orienting the reader, we start this chapter by outlining some of the key tenets of postcolonialism. This must of necessity be brief and unsatisfactory, not least because postcolonialism itself is a slippery term, representing the gathering together of a variety of theoretical writings and understandings under one rubric. Despite the increasing interest in postcolonialism in psychology, there has been little systematic discussion of the implications of this approach in terms of research. We lay the foundations of this discussion by unpicking the possibilities of postcolonialism in understanding the politics of research, specifically the politics of location, the politics of representation, and the politics of practice. We go on to consider the broad research aims postcolonial psychology should address, as well as productive sites for such research. We provide examples of qualitative research in postcolonialism.
- Full Text:
- Date Issued: 2017
Role of structural bioinformatics in drug discovery by computational SNP analysis: analyzing variation at the protein level
- Authors: Brown, David K , Tastan Bishop, Özlem
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125921 , vital:35832 , https://doi.10.1016/j.gheart.2017.01.009
- Description: With the completion of the human genome project at the beginning of the 21st century, the biological sciences entered an unprecedented age of data generation, and made its first steps toward an era of personalized medicine. This abundance of sequence data has led to the proliferation of numerous sequence-based techniques for associating variation with disease, such as genome-wide association studies and candidate gene association studies. However, these statistical methods do not provide an understanding of the functional effects of variation. Structure-based drug discovery and design is increasingly incorporating structural bioinformatics techniques to model and analyze protein targets, perform large scale virtual screening to identify hit to lead compounds, and simulate molecular interactions. These techniques are fast, cost-effective, and complement existing experimental techniques such as high throughput sequencing. In this paper, we discuss the contributions of structural bioinformatics to drug discovery, focusing particularly on the analysis of nonsynonymous single nucleotide polymorphisms. We conclude by suggesting a protocol for future analyses of the structural effects of nonsynonymous single nucleotide polymorphisms on proteins and protein complexes.
- Full Text:
- Date Issued: 2017
Temperature-dependence of time-resolved optically stimulated luminescence and composition heterogeneity of synthetic α-Al2O3: C
- Authors: Chithambo, Makaiko L , Costin, G
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124172 , vital:35573 , https://doi.org/10.1016/j.jlumin.2016.10.038
- Description: The relationship of pulse-width, lifetime and measurement temperature in describing intensity of time-resolved luminescence optically stimulated at 470 nm from α-Al2O3:C is reported. The change of luminescence intensity with stimulation temperature is discussed in terms of the signal integrated over a complete time-resolved luminescence spectrum or in terms of ratios of the signal emitted either during or after pulsed stimulation to the total signal obtained per spectrum. The temperature-induced change in these parameters depends on whether the pulse-width is less or more than the luminescence lifetime. This is because the lifetime in α-Al2O3:C varies with measurement temperature. We have developed and applied new models to distinguish thermal assistance from different traps and to use this information as an additional means to analyse thermal quenching by using the luminescence intensity integrated from time-resolved spectra. Using a model based on use of the throughput, the activation energy for thermal assistance was determined for the shallow trap as 0.054±0.001 eV and as 0.53±0.03 eV for the main trap. The activation energy for thermal quenching was then evaluated using luminescence yield during the pulse as 1.09±0.01 eV and as 1.12±0.01 eV using the throughput after the pulse. Using the new analytical method based on integrated intensity, the activation energy for thermal quenching was found as 1.00±0.07 eV. These values are self-consistent and show that the methods for analyzing temperature-induced changes in intensity and the attendant thermal effects, such as thermal assistance can be successfully applied. We have also reported a general mathematical model that accounts for the temperature-dependence of time-resolved luminescence from α-Al2O3:C. The luminescence study was complemented by investigation of the phase and composition heterogeneity of the samples.
- Full Text: false
- Date Issued: 2017
The culture hut concept as curriculum innovation: Engaging the dialectic nature of heritage in Zimbabwean schools to support ESD learning
- Authors: Zazu, Cryton
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436895 , vital:73314 , ISBN 978-3-319-45989-9 , https://doi.org/10.1007/978-3-319-45989-9_5
- Description: Influenced by Zimbabwe’s cultural policy of 2004, the culture hut concept entails the establishment of a culture hut or village within schools as a curriculum innovation aimed at promoting the teaching and learning of culture within the country’s formal education system. The culture hut is representative of what can be viewed as a ‘mini cultural museum’ in which cultural ar-tefacts and objects are displayed. All schools in Zimbabwe are, therefore, as a matter of policy expected to have a culture hut; hence the culture hut concept itself as a curriculum innovation has, since 2004, became popular in the country. Despite its popularity, little research has been done to evaluate how this curriculum innovation is adding value to Zimbabwe’s education system. It is against this background that this chapter interro-gates the culture hut concept in Zimbabwe, pointing out some of the shortfalls in its current application and highlighting how, if carefully constituted, such curriculum innovation can foster the type of learning envisaged within the Education for Sus-tainable Development (ESD) framework. This chapter, as much as it provides a critique of how the culture hut concept is being used in Zimbabwean schools, also points to what could be done to reconstitute and use this curriculum innovation in ways that support more ESD learning.
- Full Text:
- Date Issued: 2017
Using iterative learning to improve understanding during the informed consent process in a South African psychiatric genomics study
- Authors: Campbell, Megan M , Susser, Ezra , Mall, Sumaya , Mqulwana, Sibonile G , Mndini, Michael M , Ntola, Odwa A , Nagdee, Mohamed , Zingela, Zukiswa , Van Wyk, Stephanus , Stein, Dan J
- Date: 2017
- Subjects: Informed consent (Medical law) , Patient education
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6114 , vital:45124 , https://doi.org/10.1371/journal.pone.0188466
- Description: Obtaining informed consent is a great challenge in global health research. There is a need for tools that can screen for and improve potential research participants’ understanding of the research study at the time of recruitment. Limited empirical research has been conducted in low and middle income countries, evaluating informed consent processes in genomics research. We sought to investigate the quality of informed consent obtained in a South African psychiatric genomics study. A Xhosa language version of the University of California, San Diego Brief Assessment of Capacity to Consent Questionnaire (UBACC) was used to screen for capacity to consent and improve understanding through iterative learning in a sample of 528 Xhosa people with schizophrenia and 528 controls. We address two questions: firstly, whether research participants’ understanding of the research study improved through iterative learning; and secondly, what were predictors for better understanding of the research study at the initial screening? During screening 290 (55%) cases and 172 (33%) controls scored below the 14.5 cut-off for acceptable understanding of the research study elements, however after iterative learning only 38 (7%) cases and 13 (2.5%) controls continued to score below this cut-off. Significant variables associated with increased understanding of the consent included the psychiatric nurse recruiter conducting the consent screening, higher participant level of education, and being a control. The UBACC proved an effective tool to improve understanding of research study elements during consent, for both cases and controls. The tool holds utility for complex studies such as those involving genomics, where iterative learning can be used to make significant improvements in understanding of research study elements. The UBACC may be particularly important in groups with severe mental illness and lower education levels. Study recruiters play a significant role in managing the quality of the informed consent process.
- Full Text:
- Date Issued: 2017
Art investment in South Africa: portfolio diversification and art market efficiency
- Authors: Botha, Ferdi , Snowball, Jeanette D , Scott, Brett
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/64794 , vital:28601 , http://www.dx.doi.org/10.17159/2222-3436/2016/v19n3a4
- Description: Art has been suggested as a good way to diversify investment portfolios during times of financial uncertainty. The argument is that art exhibits different risk and return characteristics to conventional investments in other asset classes. The new Citadel art price index offered the opportunity to test this theory in the South African context. Moreover, this paper tests whether art prices are efficient. The Citadel index uses the hedonic regression method with observations drawn from the top 100, 50 and 20 artists by sales volume, giving approximately 29 503 total auction observations. The Index consists of quarterly data from the period 2000Q1 to 2013Q3. A vector autoregression of the art price index, Johannesburg stock exchange all-share index, house price index, and South African government bond index were used. Results show that, when there are increased returns on the stock market in a preceding period and wealth increases, there is a change in the Citadel art price index in the same direction. No significant difference was found between the house price index and the art price index, or between the art and government bond price indices. The art market is also found to be inefficient, thereby exacerbating the risk of investing in art. Overall, the South African art market does not offer the opportunity to diversify portfolios dominated by either property, bonds, or shares.
- Full Text:
- Date Issued: 2016
Assessment of water quality based on diatom indices in a small temperate river system, Kowie River, South Africa
- Authors: Dalu, Tatenda , Bere, Taurai , Froneman, P William
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123896 , vital:35514 , http://dx.doi.org/10.4314/wsa.v42i2.02
- Description: This study aimed to assess the impact of land use patterns on water quality and benthic diatom community structure and to test the applicability of diatom indices developed in other regions of the world to a small temperate southern African river system. Sampling was conducted at eight study sites along the length of the river on four separate occasions. Multivariate data analyses were performed on the diatom community dataset to specify the main gradients of floristic variation and to detect and visualize similarities in diatom samples in relation to land-use patterns within the catchment. One hundred and twelve (112) diatom species belonging to 36 genera were recorded during the study. Canonical correspondence analysis (CCA) demonstrated that variations in the benthic diatom community structure were best explained by ammonium, nitrate, conductivity, pH, temperature, resistivity and water flow. OMNIDIA was used for calculation of selected diatom water quality indices. A number of the indices, e.g., the trophic diatom index (TDI), eutrophication/pollution index and biological index of water quality (BIWQ), either under- or over-estimated the water quality of the system. With few exceptions, there were no significant correlations (p> 0.05) between the diatom indices’ values and the nutrient variables. The absence of any significant correlations between the diatom indices’ values and selected physico-chemical variables suggests that indices developed in other regions of the world may not be suitable for temperate southern African rivers.
- Full Text:
- Date Issued: 2016
Detecting derivative malware samples using deobfuscation-assisted similarity analysis
- Authors: Wrench, Peter , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429494 , vital:72617 , 10.23919/SAIEE.2016.8531543
- Description: The abundance of PHP-based Remote Access Trojans (or web shells) found in the wild has led malware researchers to develop systems capable of tracking and analysing these shells. In the past, such shells were ably classified using signature matching, a process that is currently unable to cope with the sheer volume and variety of web-based malware in circulation. Although a large percentage of newly-created webshell software incorporates portions of code derived from seminal shells such as c99 and r57, they are able to disguise this by making extensive use of obfuscation techniques intended to frustrate any attempts to dissect or reverse engineer the code. This paper presents an approach to shell classification and analysis (based on similarity to a body of known malware) in an attempt to create a comprehensive taxonomy of PHP-based web shells. Several different measures of similarity were used in conjunction with clustering algorithms and visualisation techniques in order to achieve this. Furthermore, an auxiliary component capable of syntactically deobfuscating PHP code is described. This was employed to reverse idiomatic obfuscation constructs used by software authors. It was found that this deobfuscation dramatically increased the observed levels of similarity by exposing additional code for analysis.
- Full Text:
- Date Issued: 2016
Emergent effects of structural complexity and temperature on predator–prey interactions
- Authors: Wasserman, Ryan J , Alexander, Mhairi E , Weyl, Olaf L F , Barrios‐O'Neill, Daniel , Froneman, P William , Dalu, Tatenda
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69190 , vital:29444 , https://doi.org/10.1002/ecs2.1239
- Description: Ephemeral aquatic environments are important habitats for a variety of species. They are highly variable with regards to vegetation structure and physico‐chemical features that potentially mediate outcomes of biotic interactions. Multiple environmental variables and their emergent impacts on the relationship between prey consumption rate by a predator and prey density (functional response), however, are rarely assessed. Here, we investigated the combined effects of temperature and habitat complexity on the functional response of the freshwater predatory notonectid Enithares sobria on the cladoceran prey organism Daphnia longispina. A Type II functional response was observed for E. sobria predating on D. longispina and while temperature and habitat complexity had no effect on the response type, these environmental variables interacted with consequences for the magnitude of the functional responses. Overall, structural complexity favored the predator as greater consumption was observed in the most complex habitat treatment. Temperature effects were also evident although these effects were not unidirectional with regard to treatment factor gradients as predators were the most successful at intermediary temperatures. Furthermore, there was a complex interplay between habitat complexity and temperature, with attack rates being greatest at low and high complexities within intermediate temperatures, while at zero complexity attack rates were greatest at the lowest temperature. The effect of habitat on handling times was only evident in the low temperature treatments which decreased steadily with each increase in complexity. Through the application of functional responses the synergistic effects of multiple environmental drivers on predator–prey interaction outcomes have been highlighted, adding insight into how interactions among species may be affected by natural or artificially induced environmental variability.
- Full Text:
- Date Issued: 2016
Enactivism as a powerful theoretical framework for research and tool to reflect on my own role as a supervisor:
- Authors: Schäfer, Marc
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141102 , vital:37944 , DOI: 10.1080/18117295.2016.1243938
- Description: Enactivism, as an interesting and useful theoretical underpinning is gaining traction in Mathematics Education research. It forms the central theme of this paper whose aim is two-fold: first to describe and engage with how elements of enactivism informed a PhD study, both on a theoretical and analytical level, and second to reflect on the enacted role of the supervisor of this study. Despite the inevitable embodied relationship between the supervisor and the supervised PhD project, it is not often written about. This paper thus attempts to address this. The PhD study in question used constructs of enactivism such as autonomy, sense-making, emergence, embodiment and experience to design a pre-service mathematics education programme and then explored the growth of student teachers’ mathematical identity and disposition in their development of becoming mathematics teachers. The PhD supervision process was framed by the enactivist notion that learning and the construction of meaning and knowledge is co-created by the lecturer, the student and the particular context.
- Full Text:
- Date Issued: 2016
Exploring the potential impacts of tourism development on social and ecological change in the Solomon Islands
- Authors: Diedrich, Amy , Aswani, Shankar
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67335 , vital:29074 , https://doi.org/10.1007/s13280-016-0781-x
- Description: publisher version , Pacific Island communities may be vulnerable to negative impacts of economic development, which is often considered a strategy for reducing vulnerability to environmental change. Studies that evaluate potential impacts of economic development in isolated communities may be inaccurate to only focus on asking people to anticipate impacts of phenomena they have had minimal exposure to. We used an open-ended approach to evaluate how communities in the Solomon Islands perceived change, and used this information to anticipate potential impacts of the government’s plans to develop tourism. Our results showed mostly negative expectations of change, particularly socio-cultural, which was perceived as being driven by diminishing social capital, foreign influence, and economic development. Despite minimal exposure, locals supported tourism and had more positive expectations of change associated with this activity. Our findings emphasize the need for locally appropriate planning to ensure intended positive impacts of tourism and other forms of economic development.
- Full Text: false
- Date Issued: 2016
Purification and characterization of β-mannanase from Aspergillus terreus and its applicability in depolymerization of mannans and saccharification of lignocellulosic biomass
- Authors: Soni, Hemant , Rawat, Hemant Kumar , Kango, Naveen
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66167 , vital:28912 , https://doi.org/10.1007/s13205-016-0454-2
- Description: publisher version , Aspergillus terreus FBCC 1369 was grown in solid-state culture under statistically optimized conditions. β-Mannanase was purified to apparent homogeneity by ultrafiltration, anion exchange and gel filtration chromatography. A purification factor of 10.3-fold was achieved, with the purified enzyme exhibiting specific activity of 53 U/mg protein. The purified β-mannanase was optimally active at pH 7.0 and 70 °C and displayed stability over a broad pH range of 4.0–8.0 and a 30 min half-life at 80 °C. The molecular weight of β-mannanase was calculated as ~49 kDa by SDS-PAGE. The enzyme exhibited K m and V maxvalues of 5.9 mg/ml and 39.42 µmol/ml/min, respectively. β-Mannanase activity was stimulated by β-mercaptoethanol and strongly inhibited by Hg2+. The β-Mannanase did not hydrolyze mannobiose and mannotriose, but only mannotetraose liberating mannose and mannotriose. This indicated that at least four mannose residues were required for catalytic activity. Oligosaccharide with a degree of polymerization (DP) three was the predominant product in the case of locust bean gum (16.5 %) and guar gum (15.8 %) hydrolysis. However, the enzyme liberated DP4 oligosaccharide (24 %) exclusively from konjac gum. This property can be exploited in oligosaccharides production with DP 3–4. β-Mannanase hydrolyzed pretreated lignocelluloses and liberated reducing sugars (% theoretical yield) from copra meal (30 %). This property is an important factor for the bioconversion of the biomass.
- Full Text: false
- Date Issued: 2016
Subcellular localisation of Theiler's murine encephalomyelitis virus (TMEV) capsid subunit VP1 vis-á-vis host protein Hsp90:
- Authors: Ross, Caroline J , Upfold, Nicole , Luke, Garry A , Tastan Bishop, Özlem , Knox, Caroline M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148016 , vital:38702 , DOI: 10.1016/j.virusres.2016.06.003
- Description: The VP1 subunit of the picornavirus capsid is the major antigenic determinant and mediates host cell attachment and virus entry. To investigate the localisation of Theiler's murine encephalomyelitis virus (TMEV) VP1 during infection, a bioinformatics approach was used to predict a surface-exposed, linear epitope region of the protein for subsequent expression and purification. This region, comprising the N-terminal 112 amino acids of the protein, was then used for rabbit immunisation, and the resultant polyclonal antibodies were able to recognise full length VP1 in infected cell lysates by Western blot. Following optimisation, the antibodies were used to investigate the localisation of VP1 in relation to Hsp90 in infected cells by indirect immunofluorescence and confocal microscopy.
- Full Text:
- Date Issued: 2016
Teacher code switching consistency and precision in a multilingual mathematics classroom:
- Authors: Chikiwa, Clemence , Schäfer, Marc
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141087 , vital:37943 , https://doi.org/10.1080/18117295.2016.1228823
- Description: This paper reports on a study that investigated teacher code switching consistency and precision in multilingual secondary school mathematics classrooms in South Africa. Data was obtained through interviewing and observing five lessons of each of three mathematics teachers purposively selected from three township schools in the Eastern Cape Province. Elements of Gumperz and Mercer’s work on lesson categories and Dowling’s Domains of Mathematical Practice were used to analyse data. Results showed that code switching frequency in general was inconsistent across different lessons for the same teacher.
- Full Text:
- Date Issued: 2016
Time-resolved luminescence from quartz: an overview of contemporary developments and applications
- Authors: Chithambo, Makaiko L , Pagonis, Vasilis , Ankjærgaard, Christina
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124743 , vital:35658 , https://doi.org/10.1016/j.physb.2015.10.014
- Description: Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz–feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.
- Full Text: false
- Date Issued: 2016
Water footprint assessment of citrus production in South Africa: A case study of the Lower Sundays River Valley
- Authors: Munro, Samantha A , Fraser, Gavin C G , Snowball, Jeanette D , Pahlow, Markus
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69240 , vital:29463 , https://doi.org/10.1016/j.jclepro.2016.06.142
- Description: Water footprint assessment is a developing method that is being increasingly applied to quantify water use, prioritise reductions, assess sustainability and provide information to achieve sustainable, efficient, and equitable water use. The objectives of this paper were to conduct a water footprint assessment of primary citrus production within the Lower Sundays River Valley in South Africa using local, high-resolution data and to examine indicators (water scarcity, pollution, efficiency, productivity and access) to determine the sustainability of blue, green and grey water footprints of a wet, dry and average year. Lemons were found to have the lowest blue and combined green-blue water footprint per ton of production across all climatic years, followed by soft citrus, valencias and navels. Valencias had the lowest, and navels the highest grey WF (relating to inorganic nitrogen). Lemons, despite their high crop water and fertiliser requirements, were regarded more economically efficient in comparison to valencias, soft citrus and navels, in that they provided higher net income and more employment hours per m3 of water in comparison to other citrus crops. In an average season, lemons generated approximately 39% more income per m3 of water than navels, despite navels being the dominant cultivar. Blue water consumption for citrus in the catchment was calculated to be 58.7 Mm3 for an average season and 89.2 Mm3 for a dry season. Due to an inter-basin transfer scheme, no physical water scarcity occurred, and both environmental and basic human needs are met. Water pollution levels related to nitrogen however, exceeded the assimilative capacity of the run-off in dry years. The area also experiences institutional and infrastructural scarcity and 14% of the population do not have access to piped water. Stakeholders and governments may use the results of water footprint assessments to determine the status of river basins, make evaluations for future water usage and the potential impacts of expanding agriculture and different management strategies. Including environmental and socio-economic indicators will also improve the integrity of water footprint assessments.
- Full Text: false
- Date Issued: 2016
Comparative photophysicochemical behavior of nanoconjugates of indium tetracarboxyphenoxy phthalocyanines covalently linked to CdTe/ZnSe/ZnO quantum dots
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7294 , http://hdl.handle.net/10962/d1020357 , http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Description: This work reports on the photophysicochemical behavior of different nanoconjugates of core/shell/shell (GSH-CdTe/ZnSe/ZnO), core/shell (GSH-CdTe/ZnSe) and core (GSH-CdTe) (quantum dots QDs) with indium tetracarboxyphenoxy phthalocyanines ((OH)InTCPPc) in dimethylsulfoxide. The fluorescence quantum yields (Φf) and lifetimes (τf, in brackets) of QDs ranged from 0.20 (13.9 ns) to 0.42 (25.6 ns). The highest Φf value was obtained for GSH-CdTe/ZnSe/ZnO (4.5) while the least was observed in GSH-CdTe/ZnSe/ZnO (7.6), the numbers in brackets refer to the sizes. For (OH)InTCPPc alone a Φf and τf values of 0.02 and 2.43 ns, respectively were obtained. In the nanoconjugates, pivotal decrease in the Φf and τf of the QDs were observed with increase in the triplet and singlet oxygen quantum yields of (OH)InTCPPc. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Full Text: false
- Date Issued: 2015