803 research outputs found

    Mean and mean square measurements of nonstationary random processes

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    Mean and mean square measurements of nonstationary random processes - orthogonal function analysis and computer simulatio

    A summary of methods for analyzing nonstation- ary data

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    Estimation of nonstationary mean values, spectral density, and correlation functions - summary of methods for analyzing nonstationary dat

    Assessment of Bridges Subjected to Vehicular Collision

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    Vehicles often collide with bridges. However, there are no available guidelines for bridge inspectors to assess damage and to make repair decisions. This project addresses this gap by investigating the behavior of steel girder bridges subjected to vehicular collision through (1) performing non-destructive field testing, (2) developing validated numerical models, and (3) performing parametric investigations to extend research findings. Field testing was performed using Digital Image Correlation (DIC) - a portable, non-destructive, photographic measurement technique. The focus was on two- and three-span continuous multi-girder steel bridges for which an exterior girder has sustained Category T damage, i.e., torsion about the longitudinal direction. This project can benefit Indiana Department of Transportation (INDOT) business processes by potentially reducing the number or amount of repairs, leading to cost savings and longer lifespans for bridges

    Median Arcuate Ligament Syndrome: A Rare Cause of Abdominal Pain That is Difficult to Identify

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    Median arcuate ligament syndrome (MALS) is a rare disease that occurs when the celiac artery is compressed by the median arcuate ligament. Patients with MALS typically present with non-specific symptoms that overlap with more common diseases. As a result, patients may undergo extensive workup and unnecessary treatments before being properly diagnosed with MALS. In this case we present a 23-year-old female with chronic postprandial abdominal pain that persisted despite undergoing a cholecystectomy. This case highlights the symptoms and imaging findings needed to diagnose MALS and thus prevent unnecessary surgical interventions

    Evaluating Reserve Strength of Girder Bridges Due to Bridge Rail Load Shedding

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    This research experimentally and numerically evaluated the reserve strength of girder bridges due to bridge rail load shedding. The investigation included: (1) performing non-destructive field testing on two steel girder bridges and one prestressed concrete girder bridge, (2) developing validated finite element numerical models, and (3) performing parametric numerical investigations using the validated numerical modeling approach. Measured data indicated that intact, integral, reinforced concrete rails participate in carrying live load. Research results culminated in recommendations to evaluate the reserve strength of girder bridges due to the participation of the rail, as well as recommendations for bridge inspectors for evaluating steel girder bridges subjected to vehicular collision

    Comparison of 20nm silver nanoparticles synthesized with and without a gold core: Structure, dissolution in cell culture media, and biological impact on macrophages

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    Widespread use of silver nanoparticles raises questions of environmental and biological impact. Many synthesis approaches are used to produce pure silver and silver-shell gold-core particles optimized for specific applications. Since both nanoparticles and silver dissolved from the particles may impact the biological response, it is important to understand the physicochemical characteristics along with the biological impact of nanoparticles produced by different processes. The authors have examined the structure, dissolution, and impact of particle exposure to macrophage cells of two 20 nm silver particles synthesized in different ways, which have different internal structures. The structures were examined by electron microscopy and dissolution measured in Rosewell Park Memorial Institute media with 10% fetal bovine serum. Cytotoxicity and oxidative stress were used to measure biological impact on RAW 264.7 macrophage cells. The particles were polycrystalline, but 20 nm particles grown on gold seed particles had smaller crystallite size with many high-energy grain boundaries and defects, and an apparent higher solubility than 20 nm pure silver particles. Greater oxidative stress and cytotoxicity were observed for 20 nm particles containing the Au core than for 20 nm pure silver particles. A simple dissolution model described the time variation of particle size and dissolved silver for particle loadings larger than 9 μg/ml for the 24-h period characteristic of many in-vitro studies

    IgG transmitted from allergic mothers decreases allergic sensitization in breastfed offspring

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    <p>Abstract</p> <p>Background</p> <p>The mechanism(s) responsible for the reduced risk of allergic disease in breastfed infants are not fully understood. Using an established murine model of asthma, we demonstrated previously that resistance to allergic airway disease transmitted from allergic mothers to breastfed offspring requires maternal B cell-derived factors.</p> <p>Objective</p> <p>The aim of this study was to investigate the role of offspring neonatal Fc receptor for IgG uptake by intestinal epithelial cells (FcRn) in this breast milk transferred protection from allergy.</p> <p>Methods</p> <p>Allergic airway disease was induced during pregnancy in C57BL/6 female mice. These allergic mothers foster nursed naive FcRn<sup>+/- </sup>or FcRn<sup>-/- </sup>progeny born to FcRn<sup>+/- </sup>females that were mated to C57BL/6J-FcRn<sup>-/- </sup>male mice. In offspring deficient in FcRn, we expected reduced levels of systemic allergen-specific IgG<sub>1</sub>, a consequence of decreased absorption of maternal IgG from the lumen of the neonatal gastrointestinal tract. Using this model, we were able to investigate how breast milk IgG affected offspring responses to allergic sensitization.</p> <p>Results</p> <p>Levels of maternal antibodies absorbed from the breast milk of allergic foster mothers were determined in weanling FcRn-sufficient or -deficient mice. Maternal transmission of allergen-specific IgG<sub>1 </sub>to breastfed FcRn<sup>-/- </sup>offspring was at levels 10<sup>3</sup>-10<sup>4 </sup>lower than observed in FcRn<sup>+/- </sup>or FcRn<sup>+/+ </sup>mice. Five weeks after weaning, when offspring were 8 wk old, mice were sensitized and challenged to evaluate their susceptibility to develop allergic airway disease. Protection, indicated by reduced parameters of disease (allergen-specific IgE in serum, eosinophilic inflammation in the airways and lung) were evident in FcRn-sufficient mice nursed as neonates by allergic mothers. In contrast, FcRn-deficient mice breastfed by the same mothers acquired limited, if any, protection from development of allergen-specific IgE and associated pathology.</p> <p>Conclusions</p> <p>FcRn expression was a major factor in determining how breastfed offspring of allergic mothers acquired levels of systemic allergen-specific IgG<sub>1 </sub>sufficient to inhibit allergic sensitization in this model.</p

    Methods for confidence interval estimation of a ratio parameter with application to location quotients

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    BACKGROUND: The location quotient (LQ) ratio, a measure designed to quantify and benchmark the degree of relative concentration of an activity in the analysis of area localization, has received considerable attention in the geographic and economics literature. This index can also naturally be applied in the context of population health to quantify and compare health outcomes across spatial domains. However, one commonly observed limitation of LQ is its widespread use as only a point estimate without an accompanying confidence interval. METHODS: In this paper we present statistical methods that can be used to construct confidence intervals for location quotients. The delta and Fieller's methods are generic approaches for a ratio parameter and the generalized linear modelling framework is a useful re-parameterization particularly helpful for generating profile-likelihood based confidence intervals for the location quotient. A simulation experiment is carried out to assess the performance of each of the analytic approaches and a health utilization data set is used for illustration. RESULTS: Both the simulation results as well as the findings from the empirical data show that the different analytical methods produce very similar confidence limits for location quotients. When incidence of outcome is not rare and sample sizes are large, the confidence limits are almost indistinguishable. The confidence limits from the generalized linear model approach might be preferable in small sample situations. CONCLUSION: LQ is a useful measure which allows quantification and comparison of health and other outcomes across defined geographical regions. It is a very simple index to compute and has a straightforward interpretation. Reporting this estimate with appropriate confidence limits using methods presented in this paper will make the measure particularly attractive for policy and decision makers

    Advancing radiology through informed leadership: summary of the proceedings of the Seventh Biannual Symposium of the International Society for Strategic Studies in Radiology (IS3R), 23–25 August 2007

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    The International Society for Strategic Studies in Radiology (IS3R) brings together thought leaders from academia and industry from around the world to share ideas, points of view and new knowledge. This article summarizes the main concepts presented at the 2007 IS3R symposium, providing a window onto trends shaping the future of radiology. Topics addressed include new opportunities and challenges in the field of interventional radiology; emerging techniques for evaluating and improving quality and safety in radiology; and factors impeding progress in molecular imaging and nanotechnology and possible ways to overcome them. Regulatory hurdles to technical innovation and drug development are also discussed more broadly, along with proposals for addressing regulators’ concerns and streamlining the regulatory process
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