The Irrefutable History of You: Distributed Ledgers and Semantics for Ubiquitous Personal Ratings

A recurring theme in the science-fiction series Black Mirror is the consequence for society of an over-focus on social networking. The episode Nosedive imagines a future in which every public interaction a person has is rated by the other parties, and every aspect of ones life depends on the overall rating computed from these. In this paper, we show how such a scenario is already technically possible using existing technologies such as distributed ledgers, and discuss means by which the negative possibilities may be ameliorated using semantic approaches

Expressing OWL axioms by English sentences: dubious in theory, feasible in practice

With OWL (Web Ontology Language) established as a standard for encoding ontologies on the Semantic Web, interest has begun to focus on the task of verbalising OWL code in controlled English (or other natural language). Current approaches to this task assume that axioms in OWL can be mapped to sentences in English. We examine three potential problems with this approach (concerning logical sophistication, information structure, and size), and show that although these could in theory lead to insuperable difficulties, in practice they seldom arise, because ontology developers use OWL in ways that favour a transparent mapping. This result is evidenced by an analysis of patterns from a corpus of over 600,000 axioms in about 200 ontologies

LinkChains: Exploring the space of decentralised trustworthy Linked Data

Distributed ledger platforms based on blockchains provide a fully distributed form of data storage which can guarantee data integrity. Certain use cases, such as medical applications, can benefit from guarantees that the results of arbitrary queries against a Linked Dataset faithfully represent its contents as originally published, without tampering or data corruption. We describe potential approaches to the storage and querying of Linked Data with varying degrees of decentralisation and guarantees of integrity, using distributed ledgers, and discuss their a priori differences in performance, storage limitations and reliability, setting out a programme for future empirical research

An Ontology for Grounding Vague Geographic Terms

Many geographic terms, such as “river” and “lake”, are vague, with no clear boundaries of application. In particular, the spatial extent of such features is often vaguely carved out of a continuously varying observable domain. We present a means of defining vague terms using standpoint semantics, a refinement of the philosophical idea of supervaluation semantics. Such definitions can be grounded in actual data by geometric analysis and segmentation of the data set. The issues raised by this process with regard to the nature of boundaries and domains of logical quantification are discussed. We describe a prototype implementation of a system capable of segmenting attributed polygon data into geographically significant regions and evaluating queries involving vague geographic feature terms

Automatic grounding of vague geographic ontology in data

In constructing an ontological theory of a domain such as geography, it is important not only to take account of the vagueness and ambiguity which is inherent in many of the relevant concepts, but also to be able to relate the high-level definitions of the theory to actual sets of data of varying kinds. Any attempt to ignore or remove vagueness and ambiguity risks errors and conflict in the ontological theory with the knowledge of different domain experts, while an inability to ground the theory in real data limits its practical use. We present here a means of structuring such a theory to handle these issues in a principled manner, which lends itself to concrete implementation. We illustrate with reference to several examples from the domain of hydrography

Addressing the cyber safety challenge: from risk to resilience

Addressing the cyber safety challenge: from risk to resilience describes the cyber safety issues emerging from a range of technology trends, how different populations are using technologies and the risks they face, and how we can effectively respond to each group’s unique cyber safety needs. Written by the University of Western Sydney for Telstra Corporation Ltd, the report advocates for continuing to move cyber safety from a ‘risk and protection’ framework to one that focuses on building digital resilience, as well as fostering trust and confidence in the online environment. To do this we need to: Address the needs of populations often neglected by current policies and programs – including adults, seniors, parents, and small to medium enterprises Continue to build the digital literacy skills of all populations, because digital literacy strongly influences users’ ability to engage safely online – this is best achieved by a hands-on learning approach Keep risk in perspective – the risks and benefits of digital participation go hand in hand Broaden the focus from awareness-raising to long-term behaviour change. As digital technologies become further integrated into the everyday lives of Australians, users are potentially exposed to greater risks. However, the risks and benefits of digital participation go hand in hand. The challenge, therefore, is to support users to minimise the risks without limiting their digital participation and their capacity to derive the full benefits of connectivity. If Australians are to benefit as either consumers or providers of online services and products in the e-commerce environment, consumer safety and trust need to be improved. Cyber safety needs to be considered against a transforming backdrop of technology trends, products and practices. While the rise of social media has tended to dominate recent debate and developments in cyber safety, particularly in relation to young people, a range of other trends is also shaping how users engage online, the risks they potentially face in the new media landscape, and the strategies used to address them. These trends include the rise of user generated content and content sharing platforms; the uptake of mobile technologies and, in particular, the adoption of smartphones; cloud computing; platform integration and single sign-on mechanisms; and the rise of GPS and location based services

Researching the benefits and opportunities for children online

Research in the last five years has documented a range of proven benefits for children of participating online, including positive impacts on formal and informal learning; health and well-being; literacy; civic and/or political participation; play and recreation; identity; belonging; peer, family and intergenerational relationships; individual and community resilience; and consumer practices (Swist et al., 2015). Even so, relatively little is understood about the various benefits and opportunities children can access online. If governments, communities, parents and children themselves are to activate the potential for digital media to support children’s rights, it is vital that research documents more systematically the relationship between the digital and children’s protection, provision and participation rights. This Method Guide situates current research on online benefits and opportunities in relation to key trends in global research on digital practice, and identifies the key issues that shape children’s capacity to maximise the positive impacts of their online engagement. It then documents some of the challenges to research, and proposes a set of principles and critical questions to guide researchers in designing appropriate studies. This Guide is not exhaustive. Rather, it aims to orient researchers in developing internationally comparable and culturally appropriate frameworks for understanding the scope and impact of the opportunities for children online

Oxygen management for optimisation of nitrogen removal in a sequencing batch reactor

In today's progressively urbanised society, there is an increasing need for cost-effective, environmentally sound technologies for the removal of nutrients (carbon, phosphorous, nitrogen) from polluted water. Nitrogen removal from wastewater is the focus of this thesis. Conventional nitrogen removal requires the two processes of aerobic nitrification followed by anoxic denitrification, which is driven by remaining reducing power. While most wastewaters contain a significant fraction of reducing power in the form of organic substrate, it is difficult to preserve the reducing power required for denitrification, due to the necessary preceding aerobic oxidation step. Consequently, one of the major limitations to complete N-removal in traditional wastewater treatment systems is the shortage of organic carbon substrate for the reduction of oxidised nitrogen (NO^2-, NO^3-), produced from nitrification. This thesis followed two main research themes that aimed to address the problem of organic carbon limitation in nitrogen removal from wastewater, by management of the oxygen supply. The first theme was the study of N-removal by simultaneous nitrification and denitrification (SND) in the novel reactor type, the sequencing batch reactor (SBR). It was aimed to increase understanding of PHB metabolism and the limiting factors of SND and then to develop a suitable on-line control strategy to manage the oxygen supply and optimise nitrogen removal by SND. The second main research theme was the application of the CANON(Completely Autotrophic Nitrogen-removal Over Nitrite) process for nitrogen removal from wastewater; a novel process that requires minimal oxygen supply and has the potential to completely circumvent the requirement for organic substrate in nitrogen removal because it is catalysed by autotrophic microorganisms - Anammox (anaerobic ammonium oxidisers) and aerobic nitrifiers. For study of the SND process, a completely automated 2 L sequencing batch reactor was developed with on-line monitoring of the dissolved oxygen concentration, pH and oxidation-reduction (ORP) potential. The SBR was operated continuously for up to 2 years and, due to its separation of different phases by time, enabled the study and optimisation of different microbial activities, including acetate uptake and conversion to PHB (feast phase), PHB hydrolysis and consumption (famine phase), nitrification and denitrification (and SND). All experimental work was performed using a mixed culture and acetate as the organic substrate. Acetate consumption and PHB production was studied under different oxygen supply rates to establish conditions that allow maximum conversion of acetate to PHB during the feast phase. Lower DO supply rates (kLa 6 - 16 h^-1) resulted in preservation of a higher proportion of acetate as PHB than at higher DO supply rates (kLa 30 and 51 h^-1). Up to 77 % of the reducing equivalents available from acetate were converted to PHB under O2-limitation, as opposed to only 54 % under O2-excess conditions, where a higher fraction of acetate was used for biomass growth. A metabolic model based on biochemical stoichiometry was developed that could reproduce the trends of the effect of oxygen on PHB production. Experimental findings and simulated results highlighted the importance of oxygen control during the feast phase of an SBR in preserving reducing power as PHB. To develop an oxygen management strategy for the aerobic famine phase,the effect of the dissolved oxygen (DO) concentration on SND, using PHB as the electron donor, was investigated. There was a clear compromise between the rate and the percentage of SND achieved at different DO concentrations. A DO setpoint of 1 mg L^-1 was optimal for both the percentage of SND (61 %) and rate of SND (4.4 mmol N. Cmol X-1. h^-1). Electron flux analysis showed that most SND activity occurred during the first hour of the aerobic famine period, when the oxygen uptake rate (due to NH4 + and PHB oxidation) was highest. Aerated denitrification ceased as soon as NH4 + was depleted. The presence of NH4 + provided an oxygen 'shield', preventing excessive penetration of oxygen into the flocs and creating larger anoxic zones for SND. PHB degradation was first order with respect to the biomass PHB concentration (dfPHB/dt = 0.19 . fPHB). The slow nature of PHB degradation made it a suitable substrate for SND, as it was degraded at a similar rate to ammonium oxidation. While DO control during the aerobic famine phase could increase nitrogen removal via SND, total N-removal in the SBR was still limited by the availability of reducing power(PHB) in the anoxic phase. The length of the aerobic phase needed to be minimised to prevent over-oxidation of PHB after NH4 + depletion. The specific oxygen uptake rate (SOUR) was found to be an effective on-line parameter that could reproducibly detect the end-point of nitrification. A simple method was developed for continuous, on-line measurement of the SOUR, which was used for automated adjustment of the aerobic phase length. Minimisation of the aerobic phase length by feedback control of the SOUR improved nitrogen removal from 69 % (without phase length control) to 86 %, during one cycle. The SOUR-aeration control technique could successfully adapt the aerobic phase length to varying wastewater types and strengths and to varying aeration conditions. The medium- and long-term effects of oxygen management on nitrogen removal was investigated by operating the SBR continuously for up to one month using DO control throughout all stages of the SBR, i.e. oxygen-limitation during the feast phase, a DO setpoint of 1 mg L-1 during the famine phase and SOUR controlled aerobic phase length. Complete oxygen management resulted in minimisation of the amount of PHB that was oxidised aerobically in each SBR cycle and caused an accumulation of cellular PHB over time. The increased availability of PHB during aeration resulted in a higher SOUR and increased N-removal by SND from 34 to 54 %. After one month of continuous SBR operation, the settling efficiency of the biomass improved from 110 mL . g-1X to less than 70 mL . g-1X and almost complete N-removal (9 %) was achieved via SND during aeration, however at a reduced rate (1.5 mmol Cmol X^-1 h^-1). Therefore, long-term oxygen management resulted in biomass with improved settling characteristics and a higher capacity for SND. Results of the first main research theme highlighted the importance of aeration control throughout all stages of the SBR for maximum N-removal via SND. The CANON process was investigated as an alternative to the use of conventional activated sludge for treatment of wastewaters limited by organic carbon substrate. The initial study of the CANON process was performed at the Kluyver Laboratory in Delft, the Netherlands, using an already established Anammox enrichment culture. The effect of extended periods of NH4 +-limitation on the CANON microbial populations was studied, to examine their ability to recover from major disturbances in feed composition. The CANON process was stable for long periods of time until the N-loading rate reached below 0.1 kg N m 3 day-1, when a third population of bacteria developed in the system (aerobic nitrite oxidisers), resulting in a decrease in N-removal from 92 % to 57 %. Nitrite oxidisers developed due to increased levels of oxygen and nitrite. This highlighted the requirement for oxygen control during the CANON process to prevent increased DO levels and growth of undesired microbes. To initiate the CANON process from a local source, Anammox was enriched from local activated sludge (Perth, Western Australia). FISH analysis (fluorescence in situ hybridisation) of the enriched Anammox strain showed that it belonged to the Order Planctomycetales, the same as all other identified Anammox strains, but represented a new species of Anammox. The enrichment culture was not inhibited by repeated exposure to oxygen, allowing initiation of an intermittently-aerated CANON process to achieve sustained, completely autotrophic ammonium removal (0.08 kg N m-3 day-1) for an extended period of time, without any addition of organic carbon substrate. Dissolved oxygen control played a critical role in achieving alternating aerobic and anaerobic ammonium oxidation. The main conclusion drawn from the study is the important role of oxygen management in achieving improved nitrogen removal. A careful oxygen management strategy can minimise wastage of reducing power to improve PHB-driven SND by activated sludge and can prevent major disturbances to the population balance in the CANON system. Oxygen management has the potential to reduce aeration costs while significantly improving nitrogen removal from wastewaters limited by organic carbon

Towards the Temporal Streaming of Graph Data on Distributed Ledgers

We present our work-in-progress on handling temporal RDF graph data using the Ethereum distributed ledger. The motivation for this work are scenarios where multiple distributed consumers of streamed data may need or wish to verify that data has not been tampered with since it was generated – for example, if the data describes something which can be or has been sold, such as domestically-generated electricity. We describe a system in which temporal annotations, and information suitable to validate a given dataset, are stored on a distributed ledger, alongside the results of fixed SPARQL queries executed at the time of data storage. The model adopted implements a graph-based form of temporal RDF, in which time intervals are represented by named graphs corresponding to ledger entries. We conclude by discussing evaluation, what remains to be implemented, and future directions

Early star catalogues of the southern sky: De Houtman, Kepler (Second and Third Classes), and Halley

De Houtman in 1603, Kepler in 1627 and Halley in 1679 published the earliest modern catalogues of the southern sky. We provide machine-readable versions of these catalogues, make some comparisons between them, and briefly discuss their accuracy on the basis of comparison with data from the modern Hipparcos Catalogue. We also compare our results for De Houtman with those by Knobel (1917) finding good overall agreement. About half of the about 200 new stars (with respect to Ptolemaios) added by De Houtman are in twelve new constellations, half in old constellations like Centaurus, Lupus and Argo. The right ascensions and declinations given by De Houtman have error distributions with widths of about 40 arcmin, the longitudes and latitudes given by Kepler have error distributions with widths of about 45 arcmin. Halley improves on this by more than an order of magnitude to widths of about 3 arcmin, and all entries in his catalogue can be identified. The measurement errors of Halley are due to a systematic deviation of his sextant (increasing with angle to 2 arcmin at 60 degrees) and random errors of 0.7 arcmin. The position errors in the catalogue of Halley are dominated by the position errors in the reference stars, which he took from Brahe.Comment: 26 pages, 58 figures. Tables will become available at CDS once the article appears in Astronomy and Astrophysic