5,529 research outputs found
Thermal front variability along the North Atlantic Current observed using microwave and infrared satellite data
No full textThermal fronts detected using multiple satellite sensors have been integrated to provide new information on the spatial and seasonal distribution of oceanic fronts in the North Atlantic. The branching of the North Atlantic Current (NAC) as it encounters the Mid-Atlantic Ridge (MAR) is reflected in surface thermal fronts, which preferentially occur at the Charlie Gibbs Fracture Zone (CGFZ) and several smaller fracture zones. North of the CGFZ there are few thermal fronts, contrasting with the region to the south, where there are frequent surface thermal fronts that are persistent seasonally and interannually. The alignment of the fronts confirms that the shallower Reykjanes Ridge north of the CGFZ is more of a barrier to water movements than the ridge to the south. Comparison of front distributions with satellite altimetry data indicates that the MAR influence on deep ocean currents is also frequently exhibited in surface temperature. The improved spatial and temporal resolution of the front analysis has revealed consistent seasonality in the branching patterns. These results contribute to our understanding of the variability of the NAC, and the techniques for visualising oceanic fronts can be applied in other regions to reveal details of surface currents that cannot be resolved using satellite altimetry or in situ measurements
Book review: diplomatic afterlives by Andrew F Cooper
No full textAndrew F. Cooper provides an in-depth study of the motivations, methods, and contributions made by former leaders as they take on new responsibilities beyond service to their national states. This is a thought-provoking read for students of politics and personalities, finds Stephen Minas
Leakage Current Mechanisms in SiGe HBTs Fabricated Using Selective and Nonselective Epitaxy
No full textSiGe heterojunction bipolar transistors (HTBs) have been fabricated using selective epitaxy for the Si collector, followed in the same growth step by nonselective epitaxy for the p+ SiGe base and n-Si emitter cap. DC electrical characteristics are compared with cross-section TEM images to identify the mechanisms and origins of leakage currents associated with the epitaxy in two different types of transistor . In the first type, the polysilicon emitter is smaller than the collector active area, so that the extrinsic base implant penetrates into the single-crystal Si and SiGe around the perimeter of the emitter and the polycrystalline Si and SiGe exrtrinsic base. In these transistors, the Bummel plots are near-ideal and there is no evidence of emitter/collector leakage. In the second type, the collector active area is smaller than the polysilicon emitter, so the extrinsic base implant only penetrates into the polysilicon extrinsic base. In these transistors, the leakage currents observed depend on the base doping level. In transistors with a low doped base, emitter/collector and emitter/base leakage is observed, whereas in transistors with a high doped base only emitter/base leakage is observed. The emitter/collector leakage is explained by punch through o fhte base caused by thinning of the SiGe base at the emitter perimeter. The emitter/base leakeage is shown to be due to Poole-Frenkel mechanism and is explained by penetration of the emitter/base depletion region into the p+ polysilicon extrinsic base at the emitter periphery. Variable collector/base reverse leakage currents are observed and a variety of mechanisms are observed, including Shockley-Read-Hall recombination, trap assisted tunneling, Poole Frenkel and band to band tunneling. These result s are explained by the presence of polysilicon grains on the sidewalls of the field oxide at the collector perimeter
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Assisting reading and analysis of text documents by visualization
No full textThe research reported here examined the use of computer generated graphics as a means to assist humans to analyse text documents which have not been subject to markup. The approach taken was to survey available visualization techniques in a broad selection of disciplines including applications to text documents, group those techniques using a taxonomy proposed in this research, then develop a selection of techniques that assist the text analysis objective. Development of the selected techniques from their fundamental basis, through their visualization, to their demonstration in application, comprises most of the body of this research. A scientific orientation employing measurements, combined with visual depiction and explanation of the technique with limited mathematics, is used as opposed to fully utilising any one of those resulting techniques for performing complete text document analysis.
Visualization techniques which apply directly to the text and those which exploit measurements produced by associated techniques are considered. Both approaches employ visualization to assist the human viewer to discover patterns which are then used in the analysis of the document. In the measurement case, this requires consideration of data with dimensions greater than three, which imposes a visualization difficulty. Several techniques for overcoming this problem are proposed. Word frequencies, Zipf considerations, parallel coordinates, colour maps, Cusum plots, and fractal dimensions are some of the techniques considered.
One direct application of visualization to text documents is to assist reading of that document by de-emphasising selected words by fading them on the display from which they are read. Three word selection techniques are proposed for the automatic selection of which words to use.
An experiment is reported which used such word fading techniques. It indicated that some readers do have improved reading speed under such conditions, but others do not. The experimental design enabled the separation of that group which did decrease reading times from the remaining readers who did not. Measurement of comprehension errors made under different types of word fading were shown not to increase beyond that obtained under normal reading conditions.
A visualization based on categorising the words in a text document is proposed which contrasts to visualization of measurements based on counts. The result is a visual impression of the word composition, and the evolution of that composition within that document.
The text documents used to demonstrates these techniques include English novels and short stories, emails, and a series of eighteenth century newspaper articles known as the Federalist Papers. This range of documents was needed because all analysis techniques are not applicable to all types of documents. This research proposes that an interactive use of the techniques on hand in a non-prescribed order can yield useful results in a document analysis. An example of this is in author attribution, i.e. assigning authorship of documents via patterns characteristic of an individual's writing style. Different visual techniques can be used to explore the patterns of writing in given text documents.
A software toolkit as a platform for implementing the proposed interactive analysis of text documents is described. How the techniques could be integrated into such a toolkit is outlined. A prototype of software to implement such a toolkit is included in this research. Issues relating to implementation of each technique used are also outlined
A 20-bit ±40-mV Range Read-Out IC With 50-nV Offset and 0.04% Gain Error for Bridge Transducers
No full textThis paper presents a 20-b read-out IC with ±40-mV full-scale range that is intended for use with bridge transducers. It consists of a current-feedback instrumentation amplifier (CFIA) followed by a switched-capacitor incremental ΔΣ ADC. The CFIA's offset and 1/ f noise are mitigated by chopping, while its gain accuracy and gain drift are improved by applying dynamic element matching to its input and feedback transconductors. Their mismatch is reduced by a digitally assisted correction loop, which further reduces the CFIA's gain drift. Finally, bulk-biasing and impedance-balancing techniques are used to reduce the common-mode dependency of these transconductors, which would otherwise limit the achievable gain accuracy. The combination of these techniques enables the read-out IC to achieve 140-dB CMRR, a worst-case gain error of 0.04% over a 0-2.5 V common-mode range, a maximum gain drift of 0.7 ppm/°C and an INL of 5 ppm. After applying nested-chopping, the read-out IC achieves 50-nV offset, 6-nV/°C offset drift, a thermal noise floor of 16.2 nV/√Hz and a 0.1-mHz 1/ f noise corner. Implemented in a 0.7-μm CMOS technology, the prototype read-out IC consumes 270 μA from a 5-V supply.Accepted Author ManuscriptElectronic Instrumentatio
Setaria viridis ME034V TE annotation table
No full textThe EDTA transposable element annotation pipeline was used to identify structural and homology based transposons in the model monocot Setaria viridis ME034V genome. Non-transposon repeats annotated by EDTA were stripped to generate these minimal TE bed files. The annotations were used in a comparative analysis of DNA methylation in wild type and a DRM disrupted methylation mutant.Structural and homology based TE annotation of the Setaria viridis ME034V genome.Read, Andrew; Liang, Zhikai. (2021). Setaria viridis ME034V TE annotation table. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/32ca-4m22
Pseudorandomness and Fourier Growth Bounds for Width-3 Branching Programs
No full textWe present an explicit pseudorandom generator for oblivious, read-once, width-3 branching programs, which can read their input bits in any order. The generator has seed length O~( log^3 n ).
The previously best known seed length for this model is n^{1/2+o(1)} due to Impagliazzo, Meka, and Zuckerman (FOCS'12). Our work generalizes a recent result of Reingold, Steinke, and Vadhan (RANDOM'13) for permutation branching programs. The main technical novelty underlying our generator is a new bound on the Fourier growth of width-3, oblivious, read-once branching programs. Specifically, we show that for any f : {0,1}^n -> {0,1} computed by such a branching program, and k in [n], sum_{|s|=k} |hat{f}(s)| < n^2 * (O(\log n))^k,
where f(x) = sum_s hat{f}(s) (-1)^ is the standard Fourier transform over Z_2^n. The base O(log n) of the Fourier growth is tight up to a factor of log log n
Gordon F. M. Rakita
No full textREAD poster of University of North Florida faculty member Gordon F. M. Rakita, Ph.D., Assistant Professor of Anthropology in the Department of Sociology and Anthropology.https://digitalcommons.unf.edu/posters/1034/thumbnail.jp
Functional constraints, usage, and mental grammars: A study of speakers’ intuitions about questions with long-distance dependencies
No full textThis paper describes an experimental study which attempts to reconcile two usage based approaches to questions with long distance dependencies (LDDs): the Lexical Template Hypothesis (Dąbrowska 2004, 2008; Verhagen 2005, 2006) and Goldberg's BCI (“Backgrounded Constituents are Islands”) constraint (Goldberg 2006; Ambridge and Goldberg 2008). The study replicates Ambridge and Goldberg's (2008) results supporting the BCI constraint; but it also shows that (1) LDD questions with think and say, the verbs which are part of the hypothesised templates, are judged to be more acceptable than predicted by BCI and (2) BCI cannot explain complementizer effects (why LDD questions with that are judged less acceptable than questions without that). The results also suggest that there are considerable individual differences in speakers' sensitivity to the constraint.
Thus, the two hypotheses are complementary: BCI explains why certain LDD questions are more acceptable than others, and hence accounts for differences in the frequency of prototypical and unprototypical LDD questions, while the lexical template hypothesis explains the effects of the frequency of use on speakers' mental grammars
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