Application of Kalman Filtering Methods to Online Real-Time Structural Identification: A Comparison Study

© 2016 World Scientific Publishing Company. System identification refers to the process of building or improving mathematical models of dynamical systems from the observed experimental input-output data. In the area of civil engineering, the estimation of the integrity of a structure under dynamic loadings and during service condition has become a challenge for the engineering community. Therefore, there has been a great deal of attention paid to online and real-time structural identification, especially when input-output measurement data are contaminated by high-level noise. Among real-time identification methods, one of the most successful and widely used algorithms for estimation of system states and parameters is the Kalman filter and its various nonlinear extensions such as extended Kalman filter (EKF), Iterated EKF (IEKF), the recently developed unscented Kalman filter (UKF) and Iterated UKF (IUKF). In this paper, an investigation has been carried out on the aforementioned techniques for their effectiveness and efficiencies through a highly nonlinear single degree of freedom (SDOF) structure as well as a two-storey linear structure. Although IEKF is an improved version of EKF, results show that IUKF generally produces better results in terms of structural parameters and state estimation than UKF and IEKF. Also IUKF is more robust to noise levels compared to the other approaches

Frustration of triplet interaction in spin-glass background

Parisi demonstrated in 1979 that pairwise interactions exhibit a glass spin phase when there is disorder. While he discovered an equilibrium solution of the Sherrington-Kirkpatrick (SK) spin-glass model and we know it as a continuous phase transition, the model dedicated to pairwise interactions and higher-order interactions has not been addressed. This research intends to determine whether this phase exists in triplet interactions. Due to the intractable nature of the three interacting spins alone, we employed a perturbation approach to provide an analytical solution for the triplet interactions in the background of the SK spin-glass model. Our results show the existence of this phase in the third-order interaction and a sudden transition that indicates a change in the nature of a glassy spin system transitioning from the continuous order to the first order. It causes a forward shift in the critical temperature by identifying the frustration of triplet interactions.Comment: 6 pages, 2 figure

Progesterone modulation of transmembrane helix-helix interactions between the α-subunit of Na/K-ATPase and phospholipid N-methyltransferase in the oocyte plasma membrane

<p>Abstract</p> <p>Background</p> <p>Progesterone binding to the surface of the amphibian oocyte initiates the meiotic divisions. Our previous studies with <it>Rana pipiens </it>oocytes indicate that progesterone binds to a plasma membrane site within the external loop between the M1 and M2 helices of the α-subunit of Na/K-ATPase, triggering a cascade of lipid second messengers and the release of the block at meiotic prophase. We have characterized this site, using a low affinity ouabain binding isoform of the α1-subunit.</p> <p>Results</p> <p>Preparations of isolated plasma membranes from <it>Rana </it>oocytes demonstrate that physiological levels of progesterone (or the non-metabolizable progestin R5020) successively activate phosphatidylethanolamine-N-methyltransferase (PE-NMT) and sphingomyelin synthase within seconds. Inhibition of PE-NMT blocks the progesterone induction of meiosis in intact oocytes, whereas its initial product, phosphatidylmonomethylethanolamine (PME), can itself initiate meiosis in the presence of the inhibitor. Published X-ray crystallographic data on Na/K-ATPase, computer-generated 3D projections, heptad repeat analysis and hydrophobic cluster analysis of the transmembrane helices predict that hydrophobic residues L, V, V, I, F and Y of helix M2 of the α1-subunit interact with F, L, G, L, L and F, respectively, of helix M3 of PE-NMT.</p> <p>Conclusion</p> <p>We propose that progesterone binding to the first external loop of the α1-subunit facilitates specific helix-helix interactions between integral membrane proteins to up-regulate PE-NMT, and, that successive interactions between two or more integral plasma membrane proteins induce the signaling cascades which result in completion of the meiotic divisions.</p

Structure and Mechanism of Ergothionase from Treponema denticola

Ergothioneine is a sulfur-containing histidine derivative that emerges from microbial biosynthesis and enters the human body through intestinal uptake and regulated distribution into specific tissues. Although the proteins involved in biosynthesis and uptake are well characterized, less is known about the degradative pathways of ergothioneine. This report describes the crystal structure of the active form of ergothionase from the oral pathogen Treponema denticola complexed with the substrate analogue desmethyl-ergothioneine sulfonic acid. This enzyme catalyzes the 1,2-elimination of trimethylamine from ergothioneine and ergothioneine sulfonic acid by using a unique mode of substrate activation combined with acid/base catalysis. This structural and mechanistic investigation revealed four essential catalytic residues, which are strictly conserved in homologous proteins from common gastrointestinal bacteria and numerous pathogenic bacteria, suggesting that bacterial activity may play an important role in determining the availability of ergothioneine in healthy and diseased human tissue

Band ratios matrix transformation (BRMT): A sedimentary lithology mapping approach using ASTER satellite sensor

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Remote sensing imagery has become an operative and applicable tool for the preparation of geological maps by reducing the costs and increasing the precision. In this study, ASTER satellite remote sensing data were used to extract lithological information of Deh-Molla sedimentary succession, which is located in the southwest of Shahrood city, Semnan Province, North Iran. A robust and effective approach named Band Ratio Matrix Transformation (BRMT) was developed to characterize and discriminate the boundary of sedimentary rock formations in Deh-Molla region. The analysis was based on the forward and continuous division of the visible-near infrared (VNIR) and the shortwave infrared (SWIR) spectral bands of ASTER with subsequent application of principal component analysis (PCA) for producing new transform datasets. The approach was implemented to ASTER spectral band ratios for mapping dominated mineral assemblages in the study area. Quartz, carbonate, and Al, Fe, Mg –OH bearing-altered minerals such as kaolinite, alunite, chlorite and mica were appropriately mapped using the BRMT approach. The results match well with geology map of the study area, fieldwork data and laboratory analysis. Accuracy assessment of the mapping result represents a reasonable kappa coefficient (0.70%) and appropriate overall accuracy (74.64%), which verified the robustness of the BRMT approach. This approach has great potential and capability for mapping sedimentary succession with diverse local–geological–physical characteristics around the world

SARS-CoV-2 Switches 'on' MAPK and NFκB Signaling via the Reduction of Nuclear DUSP1 and DUSP5 Expression

Mitogen-activated protein kinases (MAPK) and NF-kappaB (NF-κB) pathway regulate many cellular processes and are essential for immune cells function. Their activity is controlled by dual-specificity phosphatases (DUSPs). A comprehensive analysis of publicly available gene expression data sets of human airway epithelial cells (AECs) infected with SARS-CoV-2 identified DUSP1 and DUSP5 among the lowest induced transcripts within these pathways. These proteins are known to downregulate MAPK and NF-κB pathways; and their lower expression was associated with increased activity of MAPK and NF-κB signaling and enhanced expression of proinflammatory cytokines such as TNF-α. Infection with other coronaviruses did not have a similar effect on these genes. Interestingly, treatment with chloroquine and/or non-steroidal anti-inflammatory drugs counteracted the SARS-CoV-2 induced reduction of DUSP1 and DUSP5 genes expression. Therapeutically, impeding this evasion mechanism of SARS-CoV-2 may help control the exaggerated activation of these immune regulatory pathways during a COVID-19 infection

Intimal smooth muscle cells are a source but not a sensor of anti-inflammatory CYP450 derived oxylipins

AbstractVascular pathologies are associated with changes in the presence and expression of morphologically distinct vascular smooth muscle cells. In particular, in complex human vascular lesions and models of disease in pigs and rodents, an intimal smooth muscle cell (iSMC) which exhibits a stable epithelioid or rhomboid phenotype in culture is often found to be present in high numbers, and may represent the reemergence of a distinct developmental vascular smooth muscle cell phenotype. The CYP450-oxylipin - soluble epoxide hydrolase (sEH) pathway is currently of great interest in targeting for cardiovascular disease. sEH inhibitors limit the development of hypertension, diabetes, atherosclerosis and aneurysm formation in animal models. We have investigated the expression of CYP450-oxylipin-sEH pathway enzymes and their metabolites in paired intimal (iSMC) and medial (mSMC) cells isolated from rat aorta. iSMC basally released significantly larger amounts of epoxy-oxylipin CYP450 products from eicosapentaenoic acid > docosahexaenoic acid > arachidonic acid > linoleic acid, and expressed higher levels of CYP2C12, CYP2B1, but not CYP2J mRNA compared to mSMC. When stimulated with the pro-inflammatory TLR4 ligand LPS, epoxy-oxylipin production did not change greatly in iSMC. In contrast, LPS induced epoxy-oxylipin products in mSMC and induced CYP2J4. iSMC and mSMC express sEH which metabolizes primary epoxy-oxylipins to their dihydroxy-counterparts. The sEH inhibitors TPPU or AUDA inhibited LPS-induced NFκB activation and iNOS induction in mSMC, but had no effect on NFκB nuclear localization or inducible nitric oxide synthase in iSMC; effects which were recapitulated in part by addition of authentic epoxy-oxylipins. iSMCs are a rich source but not a sensor of anti-inflammatory epoxy-oxylipins. Complex lesions that contain high levels of iSMCs may be more resistant to the protective effects of sEH inhibitors

Persistent Homology of Weighted Visibility Graph from Fractional Gaussian Noise

In this paper, we utilize persistent homology technique to examine the topological properties of the visibility graph constructed from fractional Gaussian noise (fGn). We develop the weighted natural visibility graph algorithm and the standard network in addition to the global properties in the context of topology, will be examined. Our results demonstrate that the distribution of {\it eigenvector} and {\it betweenness centralities} behave as power-law decay. The scaling exponent of {\it eigenvector centrality} and the moment of {\it eigenvalue} distribution, $M_{n}$, for $n\ge1$ reveal the dependency on the Hurst exponent, $H$, containing the sample size effect. We also focus on persistent homology of $k$-dimensional topological holes incorporating the filtration of simplicial complexes of associated graph. The dimension of homology group represented by {\it Betti numbers} demonstrates a strong dependency on the Hurst exponent. More precisely, the scaling exponent of the number of $k$-dimensional topological \textit{holes} appearing and disappearing at a given threshold, depends on $H$ which is almost not affected by finite sample size. We show that the distribution function of \textit{lifetime} for $k$-dimensional topological holes decay exponentially and corresponding slope is an increasing function versus $H$ and more interestingly, the sample size effect is completely disappeared in this quantity. The persistence entropy logarithmically grows with the size of visibility graph of system with almost $H$-dependent prefactors.Comment: 17 pages, 13 figures, Comments Welcom