1,529 research outputs found
An Overview of Planning and Implementing Large-Scale Digitization
This document outlines the steps and considerations for planning and implementing a large-scale digitization project.
This document was given to the participants who attended the Nevada Statewide Large-Scale Digitization Workshop on May 18, 2018 held at UNLV Libraries
Quality measures for soil surveys by lognormal kriging
If we know the variogram of a random variable then we can compute the prediction error variances (kriging variances) for kriged estimates of the variable at unsampled sites from sampling grids of different design and density. In this way the kriging variance is a useful pre-survey measure of the quality of statistical predictions, which can be used to design sampling schemes to achieve target quality requirements at minimal cost. However, many soil properties are lognormally distributed, and must be transformed to logarithms before geostatistical analysis. The predicted values on the log scale are then back-transformed. It is possible to compute the prediction error variance for a prediction by this lognormal kriging procedure. However, it does not depend only on the variogram of the variable and the sampling configuration, but also on the conditional mean of the prediction. We therefore cannot use the kriging variance directly as a pre-survey measure of quality for geostatistical surveys of lognormal variables. In this paper we present an alternative. First we show how the limits of a prediction interval for a variable predicted by lognormal kriging can be expressed as dimensionless quantities, proportions of the unknown median of the conditional distribution. This scaled prediction interval can be used as a presurvey quality measure since it depends only on the sampling configuration and the variogram of the log-transformed variable. Second, we show how a similar scaled prediction interval can be computed for the median value of a lognormal variable across a block, in the case of block kriging. This approach is then illustrated using variograms of lognormally distributed data on concentration of elements in the soils of a part of eastern England
Review of risk from potential emerging contaminants in UK groundwater
This paper provides a review of the types of emerging organic groundwater contaminants (EGCs) which are beginning to be found in the UK. EGCs are compounds being found in groundwater that were previously not detectable or known to be significant and can come from agricultural, urban and rural point sources. EGCs include nanomaterials, pesticides, pharmaceuticals, industrial compounds, personal care products, fragrances, water treatment by-products, flame retardants and surfactants, as well as caffeine and nicotine. Many are relatively small polar molecules which may not be effectively removed by drinking water treatment. Data from the UK Environment Agency’s groundwater screening programme for organic pollutants found within the 30 most frequently detected compounds a number of EGCs such as pesticide metabolites, caffeine and DEET. Specific determinands frequently detected include pesticides metabolites, pharmaceuticals including carbamazepine and triclosan, nicotine, food additives and alkyl phosphates. This paper discusses the routes by which these compounds enter groundwater, their toxicity and potential risks to drinking water and the environment. It identifies challenges that need to be met to minimise risk to drinking water and ecosystems
Cultural Geographies
With 78 specially commissioned entries written by a diverse range of contributors, this essential reference book covers the breadth and depth of human geography to provide a lively and accessible state of the art of the discipline for ..
Digital Preservation Efforts at UNLV Libraries
A discussion of UNLV’s current digital preservation environment and our recent investigations of the digital preservation software suites Archives Direct and Preservica
Developing Scan-And-Return Collecting at UNLV Libraries
This presentation discusses how UNLV is providing access to primarysources that would otherwise remain in the hands of private individuals.Through their innovative “scan and return” process, UNLV is borrowingimportant historical documents, digitizing them, and then returning theoriginals to the owners. The digital surrogates become available throughUNLV’s Digital Collections
Implicit Hybrid Quantum-Classical CFD Calculations using the HHL Algorithm
Implicit methods are attractive for hybrid quantum-classical CFD solvers as
the flow equations are combined into a single coupled matrix that is solved on
the quantum device, leaving only the CFD discretisation and matrix assembly on
the classical device. In this paper, an implicit hybrid solver is investigated
using emulated HHL circuits. The hybrid solutions are compared with classical
solutions including full eigen-system decompositions. A thorough analysis is
made of how the number of qubits in the HHL eigenvalue inversion circuit affect
the CFD solver's convergence rates. Loss of precision in the minimum and
maximum eigenvalues have different effects and are understood by relating the
corresponding eigenvectors to error waves in the CFD solver. An iterative
feed-forward mechanism is identified that allows loss of precision in the HHL
circuit to amplify the associated error waves. These results will be relevant
to early fault tolerant CFD applications where every (logical) qubit will
count. The importance of good classical estimators for the minimum and maximum
eigenvalues is also relevant to the calculation of condition number for Quantum
Singular Value Transformation approaches to matrix inversion
Pesticides and metabolites in groundwater: examples from two major UK aquifers
Reducing the impact of anthropogenic pollution on groundwater bodies and ameliorating any deterioration of water quality is central to key legislative drivers such as the EU Water Framework Directive and the proposed daughter Directive relating to the protection of groundwater. Pesticide pollution has a direct impact on groundwater quality and an indirect impact on the associated aquatic ecosystems supported by groundwater. There is currently no legislative requirement to monitor pesticide metabolite concentrations in groundwater. Pesticide and metabolite results from two nationally important aquifers are presented, the Trassic Sandstone and the Chalk of Southern England.
Aerobic microbial degradation of diuron in the soil can
lead to the formation of three compounds; dichlorophenylmethyl urea (DCPMU), dichlorophenyl
urea (DCPU) and dichloroanaline (DCA).Median diuron concentrations were significantly higher
than each of the metabolites with outliers exceeding the
PVC on at least one occasion. At nine sites in Kent, Southern England, (60%) metabolites were more prevalent than diuron. Both aquifers are an important source of water, locally supplying up to 80% of public drinking water. The sandstone site has a predominantly arable landuse with a potential diffuse source of pesticides although soakaways are possible point sources.The chalk site has a mixture of arable and industrial/urban
landuse. A significant source has been from excessive
applications of diuron (“over-spray”) on a number of public
amenities. Data from both aquifers show that pesticide concentrations have a high degree of temporal variability. Elevated pesticide concentrations are associated with recharge events in both aquifer systems regardless of pesticide source terms. Pesticides from amenity use and diffuse agricultural sources both pose a threat to groundwater quality. Pesticide metabolites are present in significant concentrations in groundwaters. Systematic, long-term monitoring (5-10 years) is required to understand trends in groundwater quality
Getting to Know Digital Collections Users
Use and user studies can provide valuable information to archivists and librarians who wish to improve their services and systems. However, studying the use and users of digital archival collections can be challenging. This study describes the methods and findings of a study conducted by the University of Nevada, Las Vegas (UNLV) to explore questions such as, who is using UNLV Digital Collections? How are they using the materials? What are their user interface preferences? Are they satisfied? The methods used include web analytics, an online survey, and interviews. The author shares lessons learned to aid other repositories in designing and implementing digital collections assessments. The findings reveal some consistencies with past studies in user preferences over time and across different user and collection types. Study participants desired intuitive but customizable interfaces and searching and browsing functionality. They wanted the ability to easily and quickly understand the scope of the collections, and to efficiently review search results. Support for downloading high resolution files, citing materials, and creating personal collections was also apparent. Overall, study participants indicated that they are satisfied with UNLV Digital Collections, but this type of research can contribute to improvements that could attract new users and expand the reach of digital collections
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