336 research outputs found

    Microstructural changes as a time temperature indicator in cobalt superalloys and a NiCoCrAlTaY coating

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    Gas turbines in power generation systems use both nickel and cobalt-based superalloys for vanes, blades, discs and combustion chamber components. Cobalt-based superalloys have the advantage over nickel based superalloys in that they have a higher thermal conductivity and hence a greater thermal shock resistance, a greater resistance to thermal fatigue and also a better corrosion resistance. However, in some applications coatings have to be applied to such alloys because of their poor oxidation resistance. The creep strength of cobalt-based superalloys depends primarily on solid solution strengthening and the interaction between the hard carbides and alloy defects, such as dislocations and stacking faults. There is a need to develop an understanding of the microstructural changes that occur in cobalt-based superalloys, with both time and temperature, for life prediction, refurbishment and failure investigations... cont'd

    BLOOD AND TISSUE IDENTIFICATION OF SELECTED BIRDS AND MAMMALS, PART II: Cross Reaction Patterns of Birds and Mammals, Using Deer, Bovine, Raccoon, Chicken and Mallard Duck Antiserum, part 4

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    Part 4 (pp. 86-114) Mammals (Figure 10), continued Horse Human Mink Opossum Pig Porcupine. Prairie Dog Raccoon Big Horn Sheep Domestic Sheep Striped Skunk Fox Squirrel Discussio

    Human Periodontal Fibroblast Response to Enamel Matrix Derivative, Amelogenin, and Platelet‐Derived Growth Factor‐BB

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142271/1/jper1242.pd

    Premature atherosclerosis is associated with hypovitaminosis d and angiotensin-converting enzyme inhibitor non-use in lupus patients

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    The ultimate goal is to identify and target modifiable risk factors that will reduce major cardiovascular events in African American lupus patients. As a first step toward achieving this goal, this study was designed to explore risk factor models of preclinical atherosclerosis in a predominantly African American group of patients with systemic lupus erythematosus (SLE) using variables historically associated with endothelial function in nonlupus populations. Fifty-one subjects with SLE but without a history of clinical cardiovascular events were enrolled. At entry, a Framingham risk factor history and medication list were recorded. Sera and plasma samples were analyzed for lipids, lupus activity markers and total 25-hydroxyvitamin D (25 OH)D) levels. Carotid ultrasound measurements were performed to determine total plaque area (TPA) in both carotids. Cases had TPA values above age-matched controls from a vascular prevention clinic population. Logistic regression and machine learning analyses were performed to create predictive models. 25(OH)D levels were significantly lower, and SLE disease duration was significantly higher in cases. 25(OH)D levels inversely correlated with age-adjusted TPA. Angiotensin-converting enzyme (ACE) inhibitor nonuse associated with case status. Logistic regression models containing ACE inhibitor use, 25(OH)D levels and low-density lipoprotein levels had a diagnostic accuracy of 84% for predicting accelerated atherosclerosis. Similar results were obtained with machine learning models, but hydroxychlo-roquine use associated with controls in these models. This is the first study to demonstrate an association between atherosclerotic burden and 25(OH)D insufficiency or ACE inhibitor nonuse in lupus patients. These findings provide strong rationale for the study of ACE inhibitors and vitamin D replenishment as preventive therapies in this high-risk population. © Copyright 2012 Southern Society for Clinical Investigation

    Isodicentric Y Chromosomes and Sex Disorders as Byproducts of Homologous Recombination that Maintains Palindromes

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    Massive palindromes in the human Y chromosome harbor mirror-image gene pairs essential for spermatogenesis. During evolution, these gene pairs have been maintained by intrapalindrome, arm-to-arm recombination. The mechanism of intrapalindrome recombination and risk of harmful effects are unknown. We report 51 patients with isodicentric Y (idicY) chromosomes formed by homologous crossing over between opposing arms of palindromes on sister chromatids. These ectopic recombination events occur at nearly all Y-linked palindromes. Based on our findings, we propose that intrapalindrome sequence identity is maintained via noncrossover pathways of homologous recombination. DNA double-strand breaks that initiate these pathways can be alternatively resolved by crossing over between sister chromatids to form idicY chromosomes, with clinical consequences ranging from spermatogenic failure to sex reversal and Turner syndrome. Our observations imply that crossover and noncrossover pathways are active in nearly all Y-linked palindromes, exposing an Achilles' heel in the mechanism that preserves palindrome-borne genes.National Institutes of Health (U.S.)Howard Hughes Medical InstituteNetherlands Organization for Scientific ResearchUniversity of Amsterdam. Academic Medical CenterBoehringer Ingelheim (Fellowship

    Decentralization and regional government size in Spain

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    The aim of this paper is to investigate the impact of fiscal decen- tralization on the size of regional governments in Spain, by controlling for economies of scale, interregional heterogeneity and institutional framework. We study it over 1985 to 2004 using a panel dataset of seventeen spanish regions. The results can be easily summarized. Firstly, it supports the classic public goods theory of a trade-off-between the economic benefits of size and the costs of heterogeneity. Secondly, it doesn’t reject the “Leviathan” hypoth- esis and neither does the “common pool” hypothesis. Thirdly, by contrast, the paper partly rejects the “Wallis”’ hypothesis. It argues that government size is mediated by financial resources obtained through intergovernmental grants, consistent with welfare economics and positive economic policies. We conclude that later advances in the decentralisation process must be compatible with the goal of reducing fiscal imbalances that emanate from the vertical structure of fiscal power.info:eu-repo/semantics/publishedVersio

    Reversing Blood Flows Act through klf2a to Ensure Normal Valvulogenesis in the Developing Heart

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    Heart valve anomalies are some of the most common congenital heart defects, yet neither the genetic nor the epigenetic forces guiding heart valve development are well understood. When functioning normally, mature heart valves prevent intracardiac retrograde blood flow; before valves develop, there is considerable regurgitation, resulting in reversing (or oscillatory) flows between the atrium and ventricle. As reversing flows are particularly strong stimuli to endothelial cells in culture, an attractive hypothesis is that heart valves form as a developmental response to retrograde blood flows through the maturing heart. Here, we exploit the relationship between oscillatory flow and heart rate to manipulate the amount of retrograde flow in the atrioventricular (AV) canal before and during valvulogenesis, and find that this leads to arrested valve growth. Using this manipulation, we determined that klf2a is normally expressed in the valve precursors in response to reversing flows, and is dramatically reduced by treatments that decrease such flows. Experimentally knocking down the expression of this shear-responsive gene with morpholine antisense oligonucleotides (MOs) results in dysfunctional valves. Thus, klf2a expression appears to be necessary for normal valve formation. This, together with its dependence on intracardiac hemodynamic forces, makes klf2a expression an early and reliable indicator of proper valve development. Together, these results demonstrate a critical role for reversing flows during valvulogenesis and show how relatively subtle perturbations of normal hemodynamic patterns can lead to both major alterations in gene expression and severe valve dysgenesis

    Genome3D: exploiting structure to help users understand their sequences.

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    Genome3D (http://www.genome3d.eu) is a collaborative resource that provides predicted domain annotations and structural models for key sequences. Since introducing Genome3D in a previous NAR paper, we have substantially extended and improved the resource. We have annotated representatives from Pfam families to improve coverage of diverse sequences and added a fast sequence search to the website to allow users to find Genome3D-annotated sequences similar to their own. We have improved and extended the Genome3D data, enlarging the source data set from three model organisms to 10, and adding VIVACE, a resource new to Genome3D. We have analysed and updated Genome3D's SCOP/CATH mapping. Finally, we have improved the superposition tools, which now give users a more powerful interface for investigating similarities and differences between structural models

    A daily-updated tree of (sequenced) life as a reference for genome research

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    We report a daily-updated sequenced/species Tree Of Life (sTOL) as a reference for the increasing number of cellular organisms with their genomes sequenced. The sTOL builds on a likelihood-based weight calibration algorithm to consolidate NCBI taxonomy information in concert with unbiased sampling of molecular characters from whole genomes of all sequenced organisms. Via quantifying the extent of agreement between taxonomic and molecular data, we observe there are many potential improvements that can be made to the status quo classification, particularly in the Fungi kingdom; we also see that the current state of many animal genomes is rather poor. To augment the use of sTOL in providing evolutionary contexts, we integrate an ontology infrastructure and demonstrate its utility for evolutionary understanding on: nuclear receptors, stem cells and eukaryotic genomes. The sTOL (http://supfam.org/SUPERFAMILY/ sTOL) provides a binary tree of (sequenced) life, and contributes to an analytical platform linking genome evolution, function and phenotype
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