2,218 research outputs found

    A two-component polymeric optode membrane based on a multifunctional ionic liquid

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    This work details the use of a 2-component optode membrane which is capable of generating three distinct colours in the presence of Cu2+ and Co2+ ions. It has been found that the ionic liquid (IL) trihexyltetradecylphosphonium dicyanamide [P6,6,6,14][DCA] can act as plasticizer, ligand and transducer dye when used in poly(vinylchloride) (PVC) membranes, which significantly simplifies the optode membrane platform. Upon exposure to an aqueous Cu2+ solution, a yellow colour is generated within the membrane, while exposure to aqueous Co2+ solution generates a blue colour. Exposure to a solution containing both ions produces a green colour. Vibrational spectroscopy has been used to investigate molecular basis of the IL-metal binding mechanism. Analytical characteristics of the membranes including the effect of interfering ions, binding constants and the limit of detection for both ions have been estimated. Finally the case of simultaneous dual-analyte recognition is presented based on two distinct absorption maxima

    Self-indicating, simultaneous multianalyte recognition using an ionic liquid

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    Ionic Liquids (ILs) are the subject of increased diverse research worldwide due to many attractive inherent characteristics such as high thermal stability, negligible vapour pressure and physical and chemical diversity due to the many permutations possible1. We have studied the IL [P6,6,6,14][DCA] as a self-indicating, simultaneous, multianalyte recognition system for heavy metal ions such as Cu2+ and Co2+. When incorporated into a polymer membrane, this system maintains all these attractive features with the added bonus of the IL now being self-plasticizing. The optical response is obtained via co-ordination of the heavy metal to the anion [DCA]-.2 A system like this can be viewed as a building block for future chemical sensing platforms; where the system itself is responsive toward an analyte, thereby eliminating the need for a reactive chromophore. The resulting system can also be viewed as an optode containing only two components (polymer and plasticizer) as opposed to a classical 5-component optode (polymer, plasticizer, ionophore, ion-exchanger, dye). This simplification of components shows potential for further studies in electrochemical-based sensors (ISE’s). Our aim will be to present the results obtained thus far from both optical and structural characterization studies. 1. Wilkes, J. S., Green Chemistry, 2002, 4, (2), 73-80. 2. Vangdal, B.; Carranza, J.; Lloret, F.; Julve, M.; Sletten, J., Journal of the Chemical Society-Dalton Transactions 2002, (4), 566-574

    Racial Discrimination in NBA Contracts

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    Throughout NBA history, there has been discrimination that has been faced by black players. This is not limited to the compensation that black players receive compared to white players. Literature in this are showed a significant amount of discrimination occurring between white and black NBA players when holding player performance constant when looking at the mid 1980s. This changed with later literature, as analyses of the early to mid 1990s found that this discrimination had subsided in NBA contracts. This paper analyzes seasons from the early 1990s through to early 2020s to see whether this change in discriminatory practices holds true. The expected result based on racial progress that has been seen in the United States over time would be that this discrimination would continue to be eradicated form when it initially disappeared in the literature in the mid 1990s. However, this is not what is found in actuality. Instead, there is no significant evidence of racial discrimination in contracts in the mid 1990s, but significant discrimination reappears in the early 2010s and continues to grow with time through the 2021-22 NBA season. When looking for explanations of this phenomenon, attendance is not tied to the racial makeup of the team, and black players actually get drafted earlier based on NBA performance that white players do. As well as this, including popularity and excluding maximum contracts does not eliminate this racial disparity. The only reasoning found in the data in this paper is the influx of foreign players, but this does not come close to eliminating all discrimination, so the end result of heightened discrimination in the last decade is still puzzling

    US Elite Discourse on the EU as a Security Actor

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    Constructivist accounts of the EU’s emergence as a security actor typically focus on changing conceptions of the Union’s role within a European context, at both national and EU levels. But few studies have analysed how significant Others in the international system understand the EU’s evolving role, which is assumed to play an important role in EU identity construction. This thesis analyses the nature of the US elite’s discourse on the EU, assessing the relative influence of factors - internal and external to the elite - in shaping its evaluations of EU security action

    Video compression using wavelets and hierarchical motion estimation

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    This thesis investigates the benefits and the significant compression that can be obtained from data that has been decomposed using a wavelet transform. A video compression algorithm was developed that employs the wavelet transform and a hierarchical motion estimation algorithm which itself utilises benefits of the wavelet transform. Using MATLAB, a popular software tool for matrix based computation and analysis, several functions were developed which together formed the video compression algorithm. A variety of tests were conducted on a sample video sequence to ascertain the strengths and weaknesses of the techniques employed. The results, although not the same as the main comparison (MPEG- 1), show that the wavelet transform does have a huge potential for application in the area of video compression. The quality of the output also has advantages over DCT (Discrete Cosine Transform) based compression algorithms. One of the main outcomes is an awareness that the wavelet transform and the hierarchical motion estimation algorithm do provide significant compressibility, however the overheads need to be reduced as much as possible to ensure viability. There is still plenty of room for improvement and enhancement of the results achieved in this thesis. The potential benefits of wavelet based video compression are endless. With this being the early stages of the Information Era, compression (in particular video) is becoming increasingly important on a daily basis

    Preparation and Construction of Wills

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    Invariants of Tutte Partitions and a qq-Analogue

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    We describe a construction of the Tutte polynomial for both matroids and qq-matroids based on an appropriate partition of the underlying support lattice into intervals that correspond to prime-free minors, which we call a Tutte partition. We show that such partitions in the matroid case include the class of partitions arising in Crapo's definition of the Tutte polynomial, while not representing a direct qq-analogue of such partitions. We propose axioms of qq-Tutte-Grothendiek invariance and show that this yields a qq-analogue of Tutte-Grothendiek invariance. We establish the connection between the rank polynomial and the Tutte polynomial, showing that one can be obtained from the other by convolution

    American Sign Language (ASL) Literacy and ASL Literature: A Critical Appraisal

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    While there has been widespread acceptance of American Sign Language (ASL) as the language of instruction in residential schools for native/non-native ASL students and in colleges and universities as a foreign language, there has been little research on defining ASL literacy and ASL literature. In addition, while there has been academic debate on the existence or nonexistence of ASL literacy, there have been no studies that have defined and have described the characteristics of ASL literacy and ASL literature. To fill this void, this study answered the following research questions: (a) At a time when there is increasing recognition of ASL literacy, how would ASL literature be defined? (b) What are the features that characterize ASL literature? (c) What would such a literature comprise (e.g., genres)? To what extent is there a comprehensive taxonomy of genres captured in VHS and DVD publications? (d) What are examples of ASL literary works included in this taxonomy? A qualitative research design is used (Denzin & Lincoln, 2000). The methodology utilized was a cross-case analysis of five interviews (four individual interviews and one focus group interview) using the constant comparison method where the information is categorized into responses (Hewitt-Taylor, 2001). Eight native ASL respondents in the field of ASL and Deaf Studies who are knowledgeable and have expertise with ASL literature were contacted and interviewed. The rationale for this study was that such an investigation of ASL literacy and ASL literature will provide research in the field on this neglected topic. Such a study would have value and importance to the ASL culture and ASL community, who cherish the values embedded in ASL literature, as well as accomplish education goals to instruct native/non-native ASL students with quality ASL literature

    Automated annotation of landmark images using community contributed datasets and web resources

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    A novel solution to the challenge of automatic image annotation is described. Given an image with GPS data of its location of capture, our system returns a semantically-rich annotation comprising tags which both identify the landmark in the image, and provide an interesting fact about it, e.g. "A view of the Eiffel Tower, which was built in 1889 for an international exhibition in Paris". This exploits visual and textual web mining in combination with content-based image analysis and natural language processing. In the first stage, an input image is matched to a set of community contributed images (with keyword tags) on the basis of its GPS information and image classification techniques. The depicted landmark is inferred from the keyword tags for the matched set. The system then takes advantage of the information written about landmarks available on the web at large to extract a fact about the landmark in the image. We report component evaluation results from an implementation of our solution on a mobile device. Image localisation and matching oers 93.6% classication accuracy; the selection of appropriate tags for use in annotation performs well (F1M of 0.59), and it subsequently automatically identies a correct toponym for use in captioning and fact extraction in 69.0% of the tested cases; finally the fact extraction returns an interesting caption in 78% of cases

    Martian climatic events on timescales of centuries: Evidence from feature morphology in the residual south polar ice cap

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    Flat-floored, quasi-circular depressions on the southern residual cap of Mars have been observed to expand rapidly. Analysis of the size distribution combined with modeling of the growth process yields information about the ages of these features. We report on properties of a population of these features within a selected study area. We find a narrow size distribution that indicates a common formation time and a finite period during which new features were forming. Some change in environmental conditions occurred during this period, which we date at several Martian decades to centuries ago depending on modeled growth rates. We report on THEMIS data that reveals the nature of larger features outside our study area. Underlying water ice is exposed on the flat floors of these depressions near the outer walls. These features may record more than one growth phase, indicating that conditions conducive to growth may switch on and off with characteristic timescales of Martian centuries
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