5,449 research outputs found

    A monitor for the laboratory evaluation of control integrity in digital control systems operating in harsh electromagnetic environments

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    This paper presents a strategy for dynamically monitoring digital controllers in the laboratory for susceptibility to electromagnetic disturbances that compromise control integrity. The integrity of digital control systems operating in harsh electromagnetic environments can be compromised by upsets caused by induced transient electrical signals. Digital system upset is a functional error mode that involves no component damage, can occur simultaneously in all channels of a redundant control computer, and is software dependent. The motivation for this work is the need to develop tools and techniques that can be used in the laboratory to validate and/or certify critical aircraft controllers operating in electromagnetically adverse environments that result from lightning, high-intensity radiated fields (HIRF), and nuclear electromagnetic pulses (NEMP). The detection strategy presented in this paper provides dynamic monitoring of a given control computer for degraded functional integrity resulting from redundancy management errors, control calculation errors, and control correctness/effectiveness errors. In particular, this paper discusses the use of Kalman filtering, data fusion, and statistical decision theory in monitoring a given digital controller for control calculation errors

    Optimising DNA binding to carbon nanotubes by non-covalent methods

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    The use of carbon nanotubes as a gene delivery system has been extensively studied in recent years owing to its potential advantages over viral vectors. To achieve this goal, carbon nanotubes have to be functionalized to become compatible with aqueous media and to bind the genetic material. To establish the best conditions for plasmid DNA binding, we compare the dispersion properties of single-, double- and multi-walled carbon nanotubes (SWCNTs, DWCNTs and MWCNTs, respectively) functionalized with a variety of surfactants by non-covalent attachment. The DNA binding properties of the functionalized carbon nanotubes were studied and compared by electrophoresis. Furthermore, a bilayer functionalization method for DNA binding on SWCNTs was developed that utilized RNA-wrapping to solubilize the nanotubes and cationic polymers as a bridge between nanotubes and DNA

    Adequacy of Communicating Results From Screening Mammograms to African American and White Women

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    Objective. We examined whether African American women were as likely as White women to receive the results of a recent mammogram and to self-report results that matched the mammography radiology report (i.e., were adequately communicated). We also sought to determine whether the adequacy of communication was the same for normal and abnormal results. Methods. From a prospective cohort study of mammography screening, we compared self-reported mammogram results, which were collected by telephone interview, to results listed in the radiology record of 411 African American and 734 White women who underwent screening in 5 hospital-based facilities in Connecticut between October 1996 and January 1998. Using multivariate logistic regression, we identified independent predictors of inadequate communication of mammography results. Results. It was significantly more common for African American women to experience inadequate communication of screening mammography results compared with White women, after adjustment for sociodemographic, access-to-care, biomedical, and psychosocial factors. Abnormal mammogram results resulted in inadequate communication for African American women but not White women (P\u3c.001). Conclusions. African American women may not be receiving the full benefit of screening mammograms because of inadequate communication of results, particularly when mammography results are abnormal

    A review of reaction rates and thermodynamic and transport properties for an 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

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    Reaction rate coefficients and thermodynamic and transport properties are reviewed and supplemented for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium up to temperatures of 3000 K. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Curve fits are given for the various species properties for their efficient computation in flowfield codes. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in a high energy environment. Limitations of the approximate mixing laws are discussed for a mixture of ionized species. An electron number-density correction for the transport properties of the charged species is obtained. This correction has been generally ignored in the literature

    Mutual Caring-Resolving Habituation through Awareness: Supporting Meaningful Learning from Projects

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    This study used Grounded Theory methodology and developed an emergent theory of Mutual Caring. The main concern was Habituation to ineffective lessons learned sharing practices. Habituation is resolved through Mutual Caring, a socially and psychologically adaptive process. Mutual Caring involves comfortable conversations, engaging / sharing, and developing self-confidence, resulting in an enhanced wisdom pool. This paper extends the emphasis on tangible knowledge-sharing mechanisms. Mutual Caring could lead to better outcomes, such as more accessible and usable knowledge, a project management wisdom pool, and criteria for improved dyadic relationships to enhance project learning.Social Sciences and Humanities Research Council, Athabasca Universit

    System architecture of MMIC-based large aperture arrays for space application

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    The persistent trend to use millimeter-wave frequencies for satellite communications presents the challenge to design large-aperture phased arrays for space applications. These arrays, which comprise 100 to 10,000 elements, are now possible due to the advent of lightwave technology and the availability of monolithic microwave integrated circuits. In this paper, system aspects of optically controlled array design are studied. In particular, two architectures for a 40 GHz array are outlined, and the main system-related issues are examined: power budget, synchronization in frequency and phase, and stochastic effects

    Testosterone Influence on Gene Expression in Lacrimal Glands of Mouse Models of Sjögren Syndrome

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    Purpose: Sjögren syndrome is an autoimmune disorder that occurs almost exclusively in women and is associated with extensive inflammation in lacrimal tissue, an immune-mediated destruction and/or dysfunction of glandular epithelial cells, and a significant decrease in aqueous tear secretion. We discovered that androgens suppress the inflammation in, and enhance the function of, lacrimal glands in female mouse models (e.g., MRL/MpJ-Tnfrsf6lpr [MRL/lpr]) of Sjögren syndrome. In contrast, others have reported that androgens induce an anomalous immunopathology in lacrimal glands of nonobese diabetic/LtJ (NOD) mice. We tested our hypothesis that these hormone actions reflect unique, strain- and tissue-specific effects, which involve significant changes in the expression of immune-related glandular genes. Methods: Lacrimal glands were obtained from age-matched, adult, female MRL/lpr and NOD mice after treatment with vehicle or testosterone for up to 3 weeks. Tissues were processed for analysis of differentially expressed mRNAs using CodeLink Bioarrays and Affymetrix GeneChips. Data were analyzed with bioinformatics and statistical software. Results: Testosterone significantly influenced the expression of numerous immune-related genes, ontologies, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in lacrimal glands of MRL/lpr and NOD mice. The nature of this hormone-induced immune response was dependent upon the autoimmune strain, and was not duplicated within lacrimal tissues of nonautoimmune BALB/c mice. The majority of immune-response genes regulated by testosterone were of the inflammatory type. Conclusions: Our findings support our hypothesis and indicate a major role for the lacrimal gland microenvironment in mediating androgen effects on immune gene expression

    Exploring factors associated with participation in citizen science among UK museum visitors aged 40-60: A qualitative study using the theoretical domains framework and the capability opportunity motivation-behaviour model

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    Citizen science has grown as a form of public engagement in science. Middle-aged citizens who are already consuming scientific information should be a potential outreach group. Behaviour change research in citizen science participation among the demographic is lacking. A total of 47 museum visitors aged 40-60 years took part in qualitative questionnaires and semi-structured interviews. Thematic analysis with the aid of theoretical domains framework and capability opportunity motivation-behaviour model revealed eight themes: (1) limited awareness of citizen science; (2) curiosity, competence and other significant characteristics and skills; (3) important beliefs about one's capability; (4) importance of clear project purpose and impacts; (5) interest, enjoyment and incentives; (6) lasting impacts of family upbringing; (7) project details that make participation easy, better project promotion; and (8) the living environment, availability of free time and money. Addressing a maximum number of these factors with behaviour change techniques can improve the likelihood of citizen science participation
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