793 research outputs found
A systems approach to the description and interpretation of the landsurface of the northern half of the North Island, New Zealand
The paper examines a framework of approach within which landsurface analysis may be undertaken in the humid-temperate northern half of the North Island, New Zealand; an area exhibiting a wide range of lithologies and surface cover, with evidence of recent and current tectonic and volcanic activity, and undergoing active geomorphic processes'. The largely theoretical formulations of W. M. Davis, W. Penck and L. C. King are considered briefly and are rejected on both theoretical and practical grounds. General systems theory encompasses certain concepts and systems properties which have been applied by a number of geomorphologists. The open system property of dynamic equilibrium is examined, and is found to be inapplicable to the total landsurface of this region. The concepts of environment and sub-system are introduced and their relevance to the region illustrated by a physical hillslope model. Dynamic equilibrium is considered to be a possible state of certain hillslope sub-systems. Construction of a mathematical model to describe the total landsurface or the entire hillslope system is not feasible until hillslope sub-systems have been analysed. The form of a linear regression model applicable to hillslope sub-systems is introduced, and it is suggested that the pattern of the residuals from regression may be used as a statistical technique to assist in identifying .significant system boundary conditions, and to provide a quantitative indication of the influence of historical factors
The significance of vegetation, fire and man in the stabilisation of sand dunes near the Warburton Ranges, Central Australia
The vegetation cover of sand dunes and sandplain country in a part of Central Australia is aperiodically destroyed by fire, caused by lightning and Aboriginal activities. Subsequent mobilisation, transportation and redeposition of sand by wind suggests that these vegetated sand dunes are currently unstable
Human–Computer Interaction considerations when developing cyber ranges
The number of cyber-attacks are continuing to rise globally. It is therefore vital for organisations to develop the necessary skills to secure their assets and to protect critical national infrastructure. In this short paper, we outline human-computer interaction elements which should be considered when developing a cybersecurity training platform, in an effort to maintain levels of user engagement. We provide an overview of existing training platforms before covering specialist cyber ranges. Aspects of human-computer interaction are covered with regards to their relevance in the context of cyber ranges. We conclude with design suggestions when developing a cyber range platform
Pour une perspective benjaminienne du livre IV, ‘Les Feux’ des ‘Tragiques’ d’Agrippa d’Aubigné
Andrea: Unhappy the land that has no heroes!Galileo: No. Unhappy the land where heroes are not needed.B. Brecht, Life of Galileo L’Europe se monstra : Dieu vid sa contenanceFumeuse par les feux esmeus sur l’innocenceVid les publiques lieux, les palais les plus beauxPleins de peuples bruyans, qui pour les jeux nouveauxEstaloyent à la mort les plus entieres viesEn spectacles plaisans et feintes tragedies .(III, 613-618). Ces quelques vers tirés de la Chambre Dorée (III) des Tragiques par Agripp..
Exploring multispecies interactions between wine-associated yeasts
The fermentation of grape must to wine is catalysed by a diverse microbial community. Yeast are
primary drivers of the associated alcoholic fermentation process and have therefore garnered
considerable research interest. The diversity of yeast species present during wine fermentation
influences the chemical composition and related sensory properties of wine as a result of the metabolic
functioning of particular yeast species in response to abiotic and biotic factors. The latter is a relatively
new research field, given that microbiological science has a significant monoculture bias, and as such,
there is much still to be understood about the role and mechanisms of biotic stress in wine yeast
ecosystems. Moreover, while the wine yeast ecosystem was the model used in this study, there are
several other yeast ecosystems of biotechnological importance, including in biofuels production,
bioremediation and other food and beverage industries, that would benefit from insight into these
biotic stress mechanisms. The current basis of our understanding of the molecular mechanisms of yeast
interactions in the wine ecosystem is based on two-species pairings, which keeps the system interaction
network uncomplicated. However, there are many more role-players in natural ecosystems, and they
do not interact in a linear fashion. At the micro- and macroscopic level, the importance of these often
overlooked higher-order interactions has been highlighted in other ecosystems. There is very little
information on higher-order interactions in the yeast ecology field, and this must be remedied for
predictive understanding of these systems.
Here, we sought to address the current status quo in multispecies yeast research, by aiming to develop
new tools to investigate the mechanistic basis of interaction in systems comprised of more than two
species. Furthermore, the study aimed to generate a greater depth of understanding of these systems,
by investigating transcriptional responses of Saccharomyces cerevisiae to co-culture in mixed-species
cultures of increasing complexity.
Firstly, these aims were achieved by developing a fluorescence-based multi-colour flow cytometric
method for tracking of a consortium consisting of wine-associated yeast species. This involved
optimizing the genetic modification of the selected environmentally isolated yeast species, followed by
extensive validation to confirm the representativeness of the system as well as development of the flow
cytometric protocol. This was followed by addressing the pertinent issue of reproducibility in
multispecies cultures, and showing the role of the physiological state of pre-cultures in determining
their growth performance in three-species and four-species consortia. Finally, to contribute to our
understanding of the molecular mechanisms of interaction in non-linear yeast systems, we showed that
Saccharomyces cerevisiae expresses a combination of known pair-wise as well as unique genes when
grown in a three-species system. By using interactive network visualizations of the generated
transcriptomic data, we were able to functionally characterize the cellular responses in more detail than
has been done before in similar studies.Doctorat
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