218,092 research outputs found

    Design-Time Quantification of Integrity in Cyber-Physical-Systems

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    In a software system it is possible to quantify the amount of information that is leaked or corrupted by analysing the flows of information present in the source code. In a cyber-physical system, information flows are not only present at the digital level, but also at a physical level, and to and fro the two levels. In this work, we provide a methodology to formally analyse a Cyber-Physical System composite model (combining physics and control) using an information flow-theoretic approach. We use this approach to quantify the level of vulnerability of a system with respect to attackers with different capabilities. We illustrate our approach by means of a water distribution case study

    Outside the Cap: Opportunities and Limitations of Greenhouse Gas Offsets

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    Explains the role of carbon offsets in providing flexibility and containing costs in a cap-and-trade program to limit greenhouse gas emissions. Recommends rigorous quantification, verification, and enforcement criteria to ensure the caps' integrity

    Reverse transcription-quantitative polymerase chain reaction: description of a RIN-based algorithm for accurate data normalization

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    <p>Abstract</p> <p>Background</p> <p>Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is the gold standard technique for mRNA quantification, but appropriate normalization is required to obtain reliable data. Normalization to accurately quantitated RNA has been proposed as the most reliable method for in vivo biopsies. However, this approach does not correct differences in RNA integrity.</p> <p>Results</p> <p>In this study, we evaluated the effect of RNA degradation on the quantification of the relative expression of nine genes (<it>18S</it>, <it>ACTB</it>, <it>ATUB</it>, <it>B2M</it>, <it>GAPDH</it>, <it>HPRT</it>, <it>POLR2L</it>, <it>PSMB6</it> and <it>RPLP0</it>) that cover a wide expression spectrum. Our results show that RNA degradation could introduce up to 100% error in gene expression measurements when RT-qPCR data were normalized to total RNA. To achieve greater resolution of small differences in transcript levels in degraded samples, we improved this normalization method by developing a corrective algorithm that compensates for the loss of RNA integrity. This approach allowed us to achieve higher accuracy, since the average error for quantitative measurements was reduced to 8%. Finally, we applied our normalization strategy to the quantification of <it>EGFR</it>, <it>HER2 </it>and <it>HER3 </it>in 104 rectal cancer biopsies. Taken together, our data show that normalization of gene expression measurements by taking into account also RNA degradation allows much more reliable sample comparison.</p> <p>Conclusion</p> <p>We developed a new normalization method of RT-qPCR data that compensates for loss of RNA integrity and therefore allows accurate gene expression quantification in human biopsies.</p

    Demonstration of rapid and sensitive module leak certification for Space Station Freedom

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    A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 (+ or -) 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 (+ or -) 0.7, -0.4 (+ or -) 0.3, and 76 (+ or -) 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on (Delta)p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc

    Development and validation of 'AutoRIF': Software for the automated analysis of radiation-induced foci

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    Copyright @ 2012 McVean et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Background: The quantification of radiation-induced foci (RIF) to investigate the induction and subsequent repair of DNA double strands breaks is now commonplace. Over the last decade systems specific for the automatic quantification of RIF have been developed for this purpose, however to ask more mechanistic questions on the spatio-temporal aspects of RIF, an automated RIF analysis platform that also quantifies RIF size/volume and relative three-dimensional (3D) distribution of RIF within individual nuclei, is required. Results: A java-based image analysis system has been developed (AutoRIF) that quantifies the number, size/volume and relative nuclear locations of RIF within 3D nuclear volumes. Our approach identifies nuclei using the dynamic Otsu threshold and RIF by enhanced Laplacian filtering and maximum entropy thresholding steps and, has an application ‘batch optimisation’ process to ensure reproducible quantification of RIF. AutoRIF was validated by comparing output against manual quantification of the same 2D and 3D image stacks with results showing excellent concordance over a whole range of sample time points (and therefore range of total RIF/nucleus) after low-LET radiation exposure. Conclusions: This high-throughput automated RIF analysis system generates data with greater depth of information and reproducibility than that which can be achieved manually and may contribute toward the standardisation of RIF analysis. In particular, AutoRIF is a powerful tool for studying spatio-temporal relationships of RIF using a range of DNA damage response markers and can be run independently of other software, enabling most personal computers to perform image analysis. Future considerations for AutoRIF will likely include more complex algorithms that enable multiplex analysis for increasing combinations of cellular markers.This article is made available through the Brunel Open Access Publishing Fund

    Sensitivity of combustion driven damage mechanisms to instability

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    A multi-disciplinary framework is developed to evaluate the damage on gas turbine engine liners including interrelated sub-domains such as combustion dynamics, stress, modal, fracture mechanics analyses and life assessment. Comparative operation conditions for the combustion dynamics have been investigated. Excessive vibrations induced by the limit cycle operation resulted in mechanical stresses and strains on the structure. The structural integrity of both the intact and damaged test specimens have been monitored by vibration-based and thermal-based techniques during the combustion operation. The progressive damage on the damaged specimen configuration has been analyzed and linked to the combustion driven mechanisms. Damage evaluation, life assessment and physical experimental approaches have been integrated and utilized to evaluate the fatigue dominant damage in combustion liner material. This study addresses a reference in ensuring the safety and reliability of gas turbine engine combustors. The outcome provides a better understanding and a quantification of the material damage progress and the component behavior in terms of life consumption and combustion dynamics

    Early loss of blood-brain barrier integrity precedes NOX2 elevation in the prefrontal cortex of an animal model of psychosis

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    The social isolation rearing of young adult rats is a model of psychosocial stress and provides a nonpharmacological tool to study alterations reminiscent of symptoms seen in psychosis. We have previously demonstrated that social isolation in rats leads to increased oxidative stress and to cerebral NOX2 elevations. Here, we investigated early alterations in mRNA expression leading to increased NOX2 in the brain. Rats were exposed to a short period of social isolation (1 week) and real-time polymerase chain reaction (PCR) for mRNA expression of genes involved in blood-brain barrier (BBB) formation and integrity (ORLs, Vof 21 and Vof 16, Leng8, Vnr1, and Trank 1 genes) was performed. Real-time PCR experiments, immunohistochemistry, and Western blotting analysis showed an increased expression of these genes and related proteins in isolated rats with respect to control animals. The expression of specific markers of BBB integrity, such as matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9), occludin 1, and plasmalemmal vesicle associated protein-1 (PV-1), was also significantly altered after 1 week of social isolation. BBB permeability, evaluated by quantification of Evans blue dye extravasation, as well as interstitial fluid, was significantly increased in rats isolated for 1 week with respect to controls. Isolation-induced BBB disruption was also accompanied by a significant increase of Interleukin 6 (IL-6) expression. Conversely, no differences in NOX2 levels were detected at this time point. Our study demonstrates that BBB disruption precedes NOX2 elevations in the brain. These results provide new insights in the interplay of mechanisms linking psychosocial stress to early oxidative stress in the brain, disruption of the BBB, and the development of mental disorders

    Keberkesanan carta pembelajaran Omygram terhadap tahap pencapaian pelajar PVMA dalam mata pelajaran Bahasa Inggeris bagi topik plurals

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    Pembinaan bahan bantu belajar untuk tujuan PdPC sememangnya digalakkan oleh Kementerian Pendidikan Malaysia bagi meningkatkan kualiti pendidikan. Kajian ini bertujuan untuk membangun dan mengenalpasti keberkesanan carta pembelajaran Omygram terhadap tahap pencapaian pelajar PVMA dalam mata pelajaran Bahasa Inggeris bagi topik plurals. Kajian ini adalah kuasi-eksperimen yang melibatkan dua buah sekolah menengah harian di daerah Batu Pahat. Instrumen kajian yang digunakan ialah soalan ujian pra dan pasca, soal selidik dan senarai semak. Dapatan kajian telah dianalisis menggunakan perisian Statistic Package For The Social Science Version 22.0 (SPSS). Analisis deskriptif dalam bentuk frekuensi, peratus, min dan sisihan piawai digunakan semasa penganalisaan data. Ujian-t pula digunakan untuk melihat perbezaan pencapaian antara ujian pra dengan ujian pasca bagi kumpulan rawatan dan kumpulan kawalan. Kumpulan rawatan diberi set soal selidik tentang motivasi pelajar selepas menggunakan carta pembelajaran Omygram dalam PdPC. Hasil dapatan kajian mendapati bahawa, terdapat perbezaan pencapaian yang signifikan antara skor ujian pra dengan skor ujian pasca bagi kumpulan rawatan. Motivasi pelajar selepas menggunakan carta pembelajaran Omygram juga berada pada tahap tinggi

    Improvement of a method for the characterization of ultrafiltration membranes by measurements of tracers retention

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    The aim of this study is to improve protocols for assessing accurate characteristic retention curve and cut-off of membranes, thus enabling the manufacture and performance of the membrane to be monitored. Different data treatments are considered in order to determine membrane retention for fractions of tracer filtered (PEGs in the molar mass range of 1–100 kg mol−1). In the most advanced method of treatment, the observed retention is expressed as a combination of solute transfer coefficients in the boundary layer (kBL) and porous structure (kpore), and the asymptotic retention (Rinf ), which is an intrinsic characteristic of the membrane to solute as it is independent of operating conditions. The developed method has proved to be accurate and reproducible in two cases: (i) monitoring of UF membrane integrity during accelerated aging; (ii) for quantification of cut-off change due to UF membrane modification by UV grafting. We propose a simplified procedure that allows a reduction in experimental workload, without loss of sensitivity, for the most advanced method

    Rho-A prenylation and signaling link epithelial homeostasis to intestinal inflammation

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    Although defects in intestinal barrier function are discussed as a key pathogenic factor in patients with inflammatory bowel diseases (IBD), the molecular pathways driving disease-specific alterations of intestinal epithelial cells (IECs) are largely unknown. Here, we performed a novel approach to characterize the transcriptome of IECs from IBD patients using a genome wide approach. We observed disease-specific alterations in IECs with markedly impaired Rho-A signaling in active IBD patients. Localization of epithelial Rho-A was shifted to the cytosol in IBD where Rho-A activation was suppressed due to reduced expression of the Rho-A prenylation enzyme GGTase-I. The functional relevance of this pathway was highlighted by studies in mice with conditional gene targeting in which deletion of RhoA or GGTase-I in IECs caused spontaneous chronic intestinal inflammation with accumulation of granulocytes and CD4+ T cells. This phenotype was associated with cytoskeleton rearrangement and aberrant cell shedding ultimately leading to loss of epithelial integrity and subsequent inflammation. These findings uncover deficient prenylation of Rho-A as a key player in the pathogenesis of IBD. As therapeutic triggering of Rho-A signaling suppressed intestinal inflammation in mice with GGTase-I deficient IECs, our findings open new avenues for treatment of epithelial injury and mucosal inflammation in IBD patients
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