400 research outputs found

    The “Anarchy” of King Arthur’s Beginnings: The Politics that Created the Arthurian Tradition

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    “The ‘Anarchy’ of King Arthur’s Beginnings: The Politics that Created the Arthurian Tradition” examines Geoffrey of Monmouth’s Historia regum Brittaniae in a political and historical context to illuminate the 12th-century politics that started the Arthurian tradition and show how those politics influenced later works about the legendary king. Based on literary and historical research, this paper covers the transmission of politics in the Historia in three sections: a summary of the politics during the time Geoffrey wrote the Historia, an examination of the way those politics were integrated into the Historia, and finally a consideration of how the political themes of the chronicle have been transformed and changed through adaptation. This paper sets out to show the influence the Historia’s politics had on the King Arthur tradition and to argue that some features of those politics remain within the Arthurian literary tradition

    Pruning to Increase Taylor Dispersion in Physarum polycephalum Networks

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    How do the topology and geometry of a tubular network affect the spread of particles within fluid flows? We investigate patterns of effective dispersion in the hierarchical, biological transport network formed by Physarum polycephalum. We demonstrate that a change in topology - pruning in the foraging state - causes a large increase in effective dispersion throughout the network. By comparison, changes in the hierarchy of tube radii result in smaller and more localized differences. Pruned networks capitalize on Taylor dispersion to increase the dispersion capability.Comment: 5 pages, 4 figures, 11 pages supplemental materia

    Toward a common language for the psychology of physical activity: A review of Physical activity and psychological well-being and psychology of physical activity: Determinants, well-being and interventions

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    First paragraph: The potential role of physical activity as an alternative and accompanying form of prevention and management of psychological well-being is the focus of Physical Activity and Psychological Well-Being. The increasing prevalence and public health costs associated with mental health conditions are highlighted in this book's opening chapter. The authors also present a sound case for exercise in the promotion of mental health by outlining that exercise is often inexpensive, carries negligible deleterious side effects, and can be self-sustaining in that it can be maintained by the individual once basic skills have been learnt

    The Shifting Sands of Creative Thinking: Connections to Dual Process Theory

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    Dual process models of cognition suggest there are two kinds of thought: rapid, automatic Type 1 processes, and effortful, controlled Type 2 processes. Models of creative thinking also distinguish between two sets of processes: those involved in the generation of ideas, and those involved with their refinement, evaluation and/or selection. Here we review dual process models in both these literatures and delineate the similarities and differences. Both generative and evaluative creative processing modes involve elements that have been attributed to each of the dual processes of cognition. We explore the notion that creative thinking may rest upon the nature of a shifting process between generative and evaluative modes of thought. We suggest that through a synthesis application of the evidence bases on dual process models of cognition and from neuroimaging, together with developing chronometric approaches to explore the shifting process, could assist the development of interventions to facilitate creativity.Comment: 17 page

    The Impact of Hard Disk Firmware Steganography on Computer Forensics

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    The hard disk drive is probably the predominant form of storage media and is a primary data source in a forensic investigation. The majority of available software tools and literature relating to the investigation of the structure and content contained within a hard disk drive concerns the extraction and analysis of evidence from the various file systems which can reside in the user accessible area of the disk. It is known that there are other areas of the hard disk drive which could be used to conceal information, such as the Host Protected Area and the Device Configuration Overlay. There are recommended methods for the detection and forensic analysis of these areas using appropriate tools and techniques. However, there are additional areas of a disk that have currently been overlooked. The Service Area or Platter Resident Firmware Area is used to store code and control structures responsible for the functionality of the drive and for logging failing or failed sectors. This paper provides an introduction into initial research into the investigation and identification of issues relating to the analysis of the Platter Resident Firmware Area. In particular, the possibility that the Platter Resident Firmware Area could be manipulated and exploited to facilitate a form of steganography, enabling information to be concealed by a user and potentially from a digital forensic investigator

    The Impact of Hard Disk Firmware Steganography on Computer Forensics

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    <p class="JDFSLParagraph">The hard disk drive is probably the predominant form of storage media and is a primary data source in a forensic investigation. The majority of available software tools and literature relating to the investigation of the structure and content contained within a hard disk drive concerns the extraction and analysis of evidence from the various file systems which can reside in the user accessible area of the disk. It is known that there are other areas of the hard disk drive which could be used to conceal information, such as the Host Protected Area and the Device Configuration Overlay. There are recommended methods for the detection and forensic analysis of these areas using appropriate tools and techniques. However, there are additional areas of a disk that have currently been overlooked.  The Service Area or Platter Resident Firmware Area is used to store code and control structures responsible for the functionality of the drive and for logging failing or failed sectors.</p><p class="JDFSLParagraph">This paper provides an introduction into initial research into the investigation and identification of issues relating to the analysis of the Platter Resident Firmware Area. In particular, the possibility that the Platter Resident Firmware Area could be manipulated and exploited to facilitate a form of steganography, enabling information to be concealed by a user and potentially from a digital forensic investigator.</p

    Physiological winners and losers in an ocean warming hotspot: a Case study on argyrosomus off the Namibian coast, with implications for their future management

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    Anthropogenic-induced climate change is having a profound impact on aquatic ecosystems, and the resilience of fish populations will be determined by how they respond to these impacts. Changes in ocean water temperature is regarded as the most pervasive change, and affects the biological, physiological and distribution response of species, particularly ectotherms. The increasingly variable biological responses to a changing environment suggest that some species and populations will likely prove to be more tolerant than others. The northern Namibian coast is an ocean warming hotspot, with temperatures rising at approximately ten times the global average. These rapid changes are predicted to have a considerable impact on the marine fauna. One recently documented change in distribution is a southern extension of the sciaenid, Argyrosomus coronus, from southern Angola into northern Namibian waters, where it now overlaps with the closely related Namibian species, Argyrosomus inodorus. Understanding how these species perform at current and future temperatures and where they overlap is vital to optimise any adaptive management for the Argyrosomus species, which forms a large component of Namibia’s coastal commercial, recreational and subsistence fisheries. The aim of this study was to quantify the aerobic scope of both species (A. coronus and A. inodorus), to determine which Argyrosomus species will be a winner at the current and future climate predictions and to provide recommendations for the sustainable management of the Namibian Argyrosomus fishery. Intermittent flow-through respirometry was used to quantify standard and maximum metabolic rates for both species across a range of temperatures. Results showed that metabolic rates scaled positively with temperature. It appears that the aerobic scope of A. inodorus was notably higher at most temperatures (12, 15, 18 and 21˚C), while that of A. coronus was only higher at the warmest test temperature of 24˚C. This corresponded with the contemporary biogeographic patterns of each species. Based on these findings, it is likely that the warming ocean conditions in northern Namibia and the cold Lüdertiz upwelling cell south of Walvis Bay will constrain these fish to central Namibia. While both species demonstrated signs of resilience to high temperatures, it is likely that the warming conditions will increasingly favour A. coronus, and that the leading edge of their distribution will shift southward in Namibia. The distribution of A. inodorus is likely to contract, as the energy budget of those on the northern trailing edge will be compromised. To promote the sustainable utilisation of the complex Argyrosomus fishery, adaptive management strategies need to be implemented. This will only be possible with a comprehensive monitoring program, including the collection of genetic data to inform the changing proportions of the two species. To maintain the A. coronus population, the current regulations need to be re-assessed, and harvest slots should be introduced to protect juvenile A. coronus and the fecund large females of both species.Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries, 202

    Movement bahaviour of three South African inshore sparid species in rocky intertidal and shallow subtidal habitats

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    This study investigated the movement behaviour of three inshore South African sparids – blacktail (Diplodus sargus capensis), zebra (Diplodus cervinus hottentotus) and white musselcracker (Sparodon durbanensis), popular inshore fishery species caught in appreciable numbers along much of the South African coast. The first study component examined movements of juveniles in a rocky intertidal nursery area at Schoenmakerskop near Port Elizabeth. Juveniles in a single gully were tagged with Visible Implant Elastomer (VIE) and resighted at the study site on snorkelling gear over a seven-month period. Tagged zebra and musselcracker displayed limited movement between potential low tide refuges, being observed repeatedly in the same gully over the full duration of the study. However, blacktail displayed greater movements and were seen infrequently in the later period of the study, probably having undergone an ontogenetic habitat shift to subtidal areas. There was evidence that blacktail maintain use of their intertidal nursery over high tide, during which the other two species moved into shallower areas adjacent to their low tide refuge. The results of three national tagging programs were analysed to determine the movement patterns of adolescent and adult fishes. The coast-wide ORI-WWF National Voluntary Tagging Program and two dedicated research programs in marine protected areas (MPAs) at De Hoop MPA and Tsitsikamma National Park (TNP) recorded few large-scale movements of tagged adult blacktail, zebra and juvenile musselcracker. High spatial-resolution data from the TNP suggested movements were usually on scales far smaller than one km. Together with long periods at liberty for many recaptured individuals, this suggests these fishes are longterm residents of small home range areas. However, tagged musselcracker over 600 mm forklength (adults) were observed to make large-scale movements, including some in excess of 800 km from Eastern Cape to KwaZulu-Natal waters. Predominantly eastward movements of adults recaptured during the spawning season indicate seasonal spawning migrations that occur in different regions of the coast. These enable the use of prevailing oceanographic currents to disperse eggs and larvae to suitable rocky nursery habitat. The third component of this study made use of high-resolution data on the temporal and spatial distribution of catches by scientific angling in the TNP to examine the daily activity patterns of the study species in relation to diel and tidal cycles, and habitat use. Blacktail capture probability was correlated with the diurnal light cycle, with peaks close to twilight suggesting elevated crepuscular foraging activity. Catches of blacktail, zebra and small musselcracker were correlated with the tidal cycle, foraging peaking over high tide periods. All three species used shallow inshore habitats extensively for foraging, blacktail showing a preference for sandy areas, while zebra and small musselcracker preferred shallow reef. Capture probability of larger musselcracker, however, was unrelated to habitat, possibly evidence of increasing area and habitat use with an ontogenetic change in diet. The lifetime movement patterns of these three species are discussed in relation to conservation measures and their management in South African fisheries. Restricted movement throughout post-settlement life for blacktail and zebra, and during the juvenile phase for musselcracker, makes local populations vulnerable to overexploitation. At present, MPAs probably play an important role in protecting local blacktail and zebra populations from overexploitation, and limited post-settlement movements mean the degree of larval dispersal between protected and adjacent areas will likely determine the effectiveness of MPAs in enhancing fisheries for these species. By contrast, MPAs likely provide recruits to fisheries for musselcracker during ontogenetic movements and dispersal from MPAs during spawning migrations. MPAs only offer partial protection to adult musselcracker populations in the spawning season, but this could nevertheless be significant under high levels of exploitation

    Mechanistic and kinetic aspects of furfural degradation in dilute acidic media

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    Thesis (MEng)--Stellenbosch University, 2019.ENGLISH ABSTRACT: Furfural is a renewable platform chemical produced from lignocellulosic biomass. Many chemicals are derived from furfural including furfuryl alcohol, cosmetic ingredients & fragrances, flavour ingredients, nematocides & other agricultural chemicals, biofuels/fuel additives, solvents, resins, nylon, spandex (PolyTHF), etc. Furfural is mostly produced by an acid catalysed dehydration of the xylan in the biomass. The same acid catalyst also catalyses furfural degradation reactions which are known to convert furfural into formic acid and solid, insoluble, heterogeneous, carbonaceous, furan-rich macromolecules known as humins. In this study, furfural degradation was investigated, considering reaction temperatures of 140 °C - 200 °C, initial furfural concentrations of 1.5 wt% - 6 wt% and the sulfuric acid catalyst concentration of 0.5 wt% - 2 wt%. The reaction kinetics of degradation were established by fitting experimental data to the Arrhenius equation. The results showed formic acid as a significant product of furfural degradation. It was found that for each mol of degraded furfural, 0.86 mol formic acid was formed under the conditions of this study. Humins were primarily composed of bifurylic and trifurylic structures and the humins composition was independent of reaction conditions and was uniform under all reaction conditions in the present study. Combustion of humins provides a route to valorise humins but generates only 1.3% of the energy required for furfural production. In a scenario where furfural is produced from biorefinery pre-treatment stages or from pulp mill pre-hydrolysis liquor (not directly from biomass) combustion of humins is a viable application as it facilitates removal of humins which otherwise block up the system. In this study, it was found that initial furfural concentration was the most influential factor towards furfural degradation. Increasing the initial furfural concentration caused an increase in the rate of degradation, more humins were formed and more formic acid was formed. Increasing reaction temperature caused an increase in the amount of humins formed and an increase in the rate of degradation. Increasing the concentration of sulfuric acid caused an increase in the rate of degradation.AFRIKAANSE OPSOMMING: Furforaal is ʼn hernubare platform chemikalie wat vervaardig word uit lignosellulosiese biomassa. Baie chemikalieë word geproduseer uit furforaal insluitend furfurielalkohol, skoonheidsbestanddele en geure, geurbestanddele, nematodedoder en ander landbouchemikalieë, biobrandstowwe of brandstof bymiddels, oplosmiddels, hars, nylon, spandeks (PolyTHF), etc. Furforaal word meestal vervaardig deur ʼn suur gekataliseerde dehidrasie van die xilaan in die biomassa. Dieselfde suurkatalis kataliseer ook furfuraal afbrekingsreaksies wat bekend is om furfuraal na metanoësuur en soliede, onoplosbare, heterogene, koolstofryke, furaanryke makromolekules, genaamd humien, om te sit. In hierdie studie is furforaal afbreking ondersoek met inagneming van reaksietemperature van 140–200 °C, aanvanklike furfuraalkonsentrasies van 1.5–6wt.% en die swawelsuur kataliskonsentrasie van 0.5–2 wt.%. Die reaksie kinetika van afbreking is bepaal deur eksperimentele data op die Arrhenius vergelyking te pas. Die resultate het gewys dat metanoësuur ʼn beduidende produk van furfuraal afbreking is. Dis gevind dat vir elke mol van afgebreekte furfuraal, 0.86 mol metanoësuur gevorm is onder die toestande van hierdie studie. Humien het hoofsaaklik bestaan uit bifurkaat en trifurkaat strukture en die humien samestelling was onafhanklik van reaksiekondisies en was uniform onder alle reaksiekondisies in die huidige studie. Verbranding van humien verskaf ʼn roete om humien te valoriseer, maar genereer slegs 1.3% van die energie benodig vir furfuraalproduksie. In ʼn scenario waar furfuraal vervaardig word uit bioraffinadery voorbehandelingstadia, of uit pulpmeul voorhidrolise vog (nie direk uit biomassa nie) is verbranding van humien ʼn haalbare toepassing as dit verwydering van humien fasiliteer wat andersins die sisteem sou blokkeer. In hierdie studie is gevind dat reaksietemperatuur die mees beduidende faktor tot furforaal-afbreking was. Verhoging van reaksietemperatuur het ʼn verhoging in die kwantiteit van furforaal wat afbreek, ʼn verhoging in die hoeveelheid humien gevorm en verhoging in die tempo van afbreking, tot gevolg gehad. Verhoging van die aanvanklike furforaal-konsentrasie het ʼn verhoging in die tempo van afbreking gehad, meer humien is gevorm en meer mieresuur is gevorm. Verhoging in die konsentrasie van swaelsuur het ʼn verhoging in die tempo van afbreking gehad en ʼn verhoging in die hoeveelheid furforaal wat gereageer het
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