380 research outputs found
Sources and impacts of inorganic and organic fine sediment in salmonid spawning gravels in chalk rivers
No full textPoor salmonid spawning habitat due to excessive fine sediment inputs has been identified as a major factor limiting survival in chalk rivers. A lack of knowledge about the complex processes and factors affecting survival was the driver for this study and gaps in the research were identified concerning the sources of fine sediment and the impact organic material had on salmonid survival in chalk streams. Consequently the main objectives of this study were to characterise spawning habitat quality of a chalk catchment, assess the sources of sediments accumulating within artificial redds, describe the composition of organic sediments using emerging technology and to create a novel method to assess the sediment oxygen consumption of those sediments. Methods were based around a catchment wide field based monitoring programme, consisting of artificially constructed spawning gravels which allowed hyporheic measurements to be taken, and sediment analysis and sediment oxygen consumption methods were carried out using different laboratory methods. Spawning habitat characteristics of the chalk catchment were found to exhibit; low sediment accumulation rates although original levels of fine sediment were high, high organic matter content, variable intra-gravel flow and intra-gravel oxygen concentrations and groundwater influences. Primary sources of fine sediment accumulating in spawning gravels and suspended sediments were found to be attributed to catchment surface sources, namely pasture (50-68%) and arable (32-50%) using inorganic and organic parameters. Organic composition of redd gravels was found to be dominated by protein material rather than humic substances, the more commonly found fluorescent compound in freshwater systems and the sediment oxygen consumption of sediments varied throughout the catchment and was found to consume the greatest oxygen in <63?m size fraction. Application of sediment oxygen consumption rates to existing parameter based models that predict salmonid survival, highlighted the need to address the sensitivity of current models to rivers experiencing low sediment accumulation rates. Outcomes of this study further the knowledge of the sources, organic composition and sediment oxygen consumption capacity of fine sediments accumulating in spawning gravels which can lead to appropriate mitigation on chalk rivers to improve salmonid spawning habitat
Engineering properties of chalk with regards to cliff slope stability: Mechanical properties of chalk and the impact of weathering on the UCS and tensile strength
No full textCoastal chalk cliff instability is a major issue in the UK’s southern region. In order to further the understanding into what drives and influences chalk cliff collapse, a series of laboratory tests have been done on samples taken from West Melbury Marly Chalk, Seaford Chalk, Newhaven Chalk and Lewes Nodular Chalk. Tests have been done to find out if there is anisotropy in permeability, what the influence of weathering is on the tensile strength and what the influence of sea water cycles on the UCS strength is. No anisotropy permeability has been found. Significant weakening has been found due to progressive mass-loss from dissolution in vinegar. No weakening from salt water cycles has been found. Between the grey chalk and white chalk subgroups, big differences exist in the behaviour when exposed to weathering
Chalk putty: specimen preparation and aging properties
No full textChalk putty is a soil-like material that is formed when intact chalk is disturbed. Recently, it has become of special interest due to the development of offshore wind farms in the North and Baltic Seas, where in a number of sites piles are driven into chalk strata. Several pile tests reported in the literature show increased shaft capacity up to 4 months after driving. Although it is a widespread remark in the scientific publications that chalk properties improve over time, laboratory replications of this phenomenon are scarce and the results are inconclusive. The aim of this thesis is to develop a specimen preparation technique yielding representative specimens as well as feasible for commercial purposes. Thereafter, the evolution of the characteristics of chalk putty over time is assessed through laboratory tests. Triaxial with Bender Elements, Direct Simple Shear, Constant Rate of Strain and Thixotropy have been conducted on specimens aged up to 3 months. Finding that the behavior of chalk putty cannot be classified among the classic types of soils. On one hand, Constant Rate of Strain tests have shown that the response is comparable to silty soil, with a gradual transition between re-loading and virgin compression lines, leading to difficulty in the determination of the yield point. On the other hand, in shear, the critical state friction angle is in the range of dense sand. Regarding the volumetric response, there is an initial compressive response, succeeded by a constant volume phase during destructuration and eventual dilation or contraction at larger strains. Furthermore, it was determined that the material possesses thixotropic properties when mixed with de-ionized water. Finally, no increase in the shear strength or was recorded while the initial shear stiffness decreases with aging time -due to unconfined preservation of the samples. However, the ultimate dilatancy of the specimens increases over time, this may be a result of dissolved calcium carbonate during crushing and saturation which re-precipitates or re-cements around the grains.Applied Earth Science
Portraits of Leonardo da Vinci
No full textUsing an iterative method, applied to image processing, a portrait of a young man, probably a self-portrait of Leonardo da Vinci, is restored. Merging this portrait with the self-portrait in red chalk, we can have the features of a middle-aged Leonardo. This digital portrait can be compared with the image of Plato, depicted by Raphael in the Scuola di Atene, generally considered as a portrait of Leonardo. The iterative method used for the image processing had been developed by the author on previous iterative calculations used to solve the Boltzmann equatio
Blockchain technology: driving change in the scientific research workflow
No full textThe goal of this white paper is to present an objective overview of the current use of blockchain technology along the scientific research workflow and in related areas such as chemical/drug supply chains and education. It represents the culmination of three years of data gathering, including input from multiple interviews with pioneer users of the technology, as well as from more recent adopters around the globe, and recent industry technology analysts' reports. Within these pages are descriptions of successful applications of the technology at each step of the scientific research workflow - from the timestamping of ideas to funding, to actual experimentation, to the analysis of research results, and ultimately to the sharing of information and the publication of results. However, not all blockchain use cases have such a successful conclusion. In this white paper you will learn where the technology has not worked - and why - thanks to those interviewed who discussed in detail the lessons that they themselves learned during their own blockchain journey. In addition, the paper highlights the potential future uses of the technology; the pitfalls to avoid when considering its use; when and how legislation and regulatory policies come into play; and how the technology is evolving and growing stronger (some say that the fourth generation of the blockchain evolution is on the horizon!). The paper also discusses parallel developments in quantum computing, its potential impact on blockchain technology, and what developments are in progress to ensure a stable and provably secure, quantum safe alternative to the existing blockchain approaches.</p
Blockchain technology and its use along the scientific research workflow
No full textAt the Council meeting held during the 2019 World Chemistry Congress in Paris, a representative from one of IUPAC’s National Adhering Organizations raised the question “What is Blockchain Technology?” They went on to say that both “Blockchain” and “Artificial Intelligence” were prominent buzzwords and asked if IUPAC could provide information on how these technologies were impacting science in general and chemistry in particular. Coincidentally, at that same Congress, the technology had been the subject of a presentation by Richard Shute [1], one of the authors of this paper, and the technology had already captured the interest of Bonnie Lawlor, another of the authors of this paper, to the extent that she published an article in Chemistry International (CI) on the topic the following year [2]. As a result of the question raised at the Council meeting, Javier García-Martínez, IUPAC President 2022-2023, suggested that a white paper on Blockchain be developed (Note: Artificial Intelligence was made the focus of the global, virtual 2021 World Chemistry Leadership Meeting (WCLM) and a brief article on that special event was published in the July 2022 issue of CI [3])
Taking FAIR on the ChIN: The Chemistry Implementation Network
No full textThe Chemistry Implementation Network (ChIN) is focused on supporting the FAIR Data needs of the research community regarding chemical related data. Figure 1 shows the interoperation between the ChIN and key community-leading organizations.</span
Taking FAIR on the ChIN: The Chemistry Implementation Network
No full textThe Chemistry Implementation Network (ChIN) is focused on supporting the FAIR Data needs of the research community regarding chemical related data. Figure 1 shows the interoperation between the ChIN and key community-leading organizations.</span
Harmonisation of Chalk and Cheese
No full textThis is a response to Towards Harmonisation of the Construction Industry Security of Payment Legislation: A consideration of the success afforded by the East and West Coast Models in Australia by Jeremy Coggins, Robert Fenwick Elliott and Matthew Bell. Towards Harmonisation is based upon the false premise that the objectives of the East Coast and West Coast models are the same. They are chalk and cheese. Each serves a valuable purpose. Each jurisdiction needs both models. A model for a dual process incorporating both the East Coast and the West Coast models will be found in Davenport (2007).</p
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