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482. A role for receptor-operated Ca2+ entry in human pulmonary artery smooth muscle cells in response to hypoxia
- Creator:
- Tang, C., To, W. K., Meng, F., Wang, Y., and Gu, Y.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, hypoxie, hypoxia, Hypoxic pulmonary vasoconstriction (HPV), hPASMC, Transient receptor potential channel (TRPC), AMP-activated kinase (AMPK), 14, and 612
- Language:
- English
- Description:
- Hypoxic pulmonary vasoconstric tion (HPV) is an important homeostatic mechanism in which increases of [Ca2+] i are primary events. In this study, primary cultured, human pulmonary artery smooth muscle cells (hPASMC) were used to examine the role of TRPC channels in mediating [Ca2+] i elevations during hypoxia. Hypoxia (PO2 about 20 mm Hg) evoked a transient [Ca2+] i elevation that was reduced by removal of extracellular calcium. Nifedipine and verapamil, blockers of vo ltage-gated calcium channels (VGCCs), attenuated th e hypoxia-induced [Ca2+] i elevation by about 30 %, suggesting the presence of alternate Ca2+ entry pathways. Expression of TRPC1 an d TRPC6 in hPASMC were found by RT-PCR and confirmed by Western blot analysis. Antagonists for TRPC, 2APB and SKF96365, significantly reduced hypoxia-induced [Ca2+] i elevation by almost 60 %. Both TRPC6 and TRPC1 were knocked down by siRNA, the loss of TRPC6 decreased hypoxic response down to 21 % of control, whereas the knockdown of TRPC1 reduced the hypoxia respon se to 85 %, suggesting that TRPC6 might play a central role in mediating hypoxia response in hPASMC. However, blockade of PLC pathway caused only small inhibition of the hypoxia response. In contrast, AICAR, the agonist of AMP-activated kinase (AMPK), induced a gradual [Ca2+] i elevation, whereas compound C, an antagonist of AMPK, almost abolished the hypoxia response. Ho wever, co-immunoprecipitation revealed that AMPK α was not colocalized with TRPC6. Our data supports a role for TRPC6 in mediation of the [Ca2+] i elevation in response to hypoxia in hPASMC and suggests that this response may be linked to cellular energy status via an activation of AMPK., C. Tang, W. K To, F. Meng, Y. Wang, Y. Gu., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
483. A role of the coefficient of the differential term in qualitative theory of half-linear equations
- Creator:
- Řehák, Pavel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- half-linear dynamic equation, time scale, transformation, comparison theorem, and oscillation criteria
- Language:
- English
- Description:
- The aim of this contribution is to study the role of the coefficient r in the qualitative theory of the equation (r(t)Φ(y ∆))∆+p(t)Φ(y σ ) = 0, where Φ(u) = |u| α−1 sgn u with α > 1. We discuss sign and smoothness conditions posed on r, (non)availability of some transformations, and mainly we show how the behavior of r, along with the behavior of the graininess of the time scale, affect some comparison results and (non)oscillation criteria. At the same time we provide a survey of recent results acquired by sophisticated modifications of the Riccati type technique, which are supplemented by some new observations.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
484. A RSM method for nonlinear probabilistic analysis of the reinforced concrete structure failure of a nuclear power plant - type VVER 440
- Creator:
- Králik, Juraj
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- nuclear power plant VVER, probabilistic safety analysis, concrete failure, RSM, and ANSYS
- Language:
- English
- Description:
- This paper describes the reliability analysis of a concrete containment for VVER 440 under a high internal overpressure. The probabilistic safety assessment (PSA) level 3 aims at an assessment of the probability of the concrete structure failure under the excessive overpressure. The non-linear analysis of the concrete structure was considered. The uncertainties of the loads level (long-time temperature and dead loads), the material model (concrete cracking and crushing, behavior of the reinforcement and liner), degradation effects and other influences following from the inaccuracy of the calculated model and numerical methods were taken into account in the response surface method (RSM). The results of the reliability analysis of the NPP structues are presented. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
485. A sample-time adjusted feedback for robust bounded output stabilization
- Creator:
- Ordaz, Patricio, Alazki, Hussain, and Poznyak, Alexander
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- sample-time data, attractive ellipsoid, state extimation, saturated control process, and flexible arm system
- Language:
- English
- Description:
- This paper deals with a bounded control design for a class of nonlinear systems where the mathematical model may be not explicitly given. This class of uncertain nonlinear systems governed by a system of ODE with quasi-Lipschitz right-hand side and containing external perturbations as well. The Attractive Ellipsoid Method (AEM) application permits to describe the class of nonlinear feedbacks (containing a nonlinear projection operator, a linear state estimator and a feedback matrix-gain) guaranteeing a boundedness of all possible trajectories around the origin. To fulfill this property some modification of AEM are introduced: basically, some sort of sample-time corrections of the feedback parameters are required. The optimization of feedback within this class of controllers is associated with the selection of the feedback parameters which provide the trajectory converges within an ellipsoid of a "minimal size". The effectiveness of the suggested approach is illustrated by its application to a flexible arm system).
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
486. A scalar Volterra derivative for the PoU-integral
- Creator:
- Marraffa, V.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Pettis integral, McShane integral, PoU integral, and Volterra derivativ
- Language:
- English
- Description:
- A weak form of the Henstock Lemma for the PoU-integrable functions is given. This allows to prove the existence of a scalar Volterra derivative for the PoU-integral. Also the PoU-integrable functions are characterized by means of Pettis integrability and a condition involving finite pseudopartitions.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
487. A scheme for the classification of micaceous minerals
- Creator:
- Karel Melka
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, jílové minerály, clay minerals, macrocrystalline micas, IS ordered structures, ISII ordered structures, fundamental particles, 7, and 551
- Language:
- English
- Description:
- The classification scheme for micaceous minerals is described. According to the size of mineral particles micas are divided into macrocrystalline compounds and microcrystalline clay micas. Macroc rystalline micas are differentiated into (a) Mg-Fe-Al micas, (b) Li-micas, (c) micas with other cations. Vertical boundary in the suggested scheme divides micas into trioctahedral and dioctahedral members. Additional subdivision is carried out on the basis of the extent of Si substitution in tetrahedral positions of their crystal lattice. Microcrystalline (<4μm) micas are subordinate to the crystallochemical scheme for macrocrystalline micas. List of mica species together with their varieties and synonyms is in Table 2., Karel Melka., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
488. A second-order stochastic dominance portfolio efficiency measure
- Creator:
- Kopa, Miloš and Chovanec, Petr
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- stochastic dominance, CVaR, and SSD portfolio efficiency measure
- Language:
- English
- Description:
- In this paper, we introduce a new linear programming second-order stochastic dominance (SSD) portfolio efficiency test for portfolios with scenario approach for distribution of outcomes and a new SSD portfolio inefficiency measure. The test utilizes the relationship between CVaR and dual second-order stochastic dominance, and contrary to tests in Post \cite{Post} and Kuosmanen \cite{Kuosmanen}, our test detects a dominating portfolio which is SSD efficient. We derive also a necessary condition for SSD efficiency using convexity property of CVaR to speed up the computation. The efficiency measure represents a distance between the tested portfolio and its least risky dominating SSD efficient portfolio. We show that this measure is consistent with the second-order stochastic dominance relation. We find out that this measure is convex and we use this result to describe the set of SSD efficient portfolios. Finally, we illustrate our results on a numerical example.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
489. A segmentation method to handwritten word recognition
- Creator:
- Senouci, Mohamed, Liazid, Abdelkrim, Beghdadi, Hadj Ali, and Benhamamouch , Djilali
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Pattern recognition, segmentation, neural networks, and handwritten word
- Language:
- English
- Description:
- This paper presents a segmentation technique to handwritten word recognition. This technique implements an algorithm based on an analytical approach. It uses a letter sweeping procedure with a step equal to the Euclidean distance between an established reference index and the entity (the alphabet letter). Then a dissociation of this entity is achieved when this distance will reach a rate of 80%. Our experience about this segmentation technique gives a rate of 81.05% of recognition. A neural multi-layer perceptron classifier confirms the extracted segment. This procedure is successively repeated from the beginning until the end of the word. A concatenation technique is finally used to the word reconstitution.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
490. A Self Organizing Map Based Approach for Congestion Avoidance in Autonomous IP Networks
- Creator:
- Yelbasi, Özen and Germen, Emin
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Self Organizing Map, congestion avoidance, random early detection, and drop tail
- Language:
- English
- Description:
- This work presents a Self Organizing Map (SOM) based queue management approach against congestion in autonomous Internet Protocol (IP) networks. The new queue management approach is proposed with consideration to the pros and cons of two well-known queue management algorithms: Random Early Detection (RED) and Drop Tail (DT). At the beginning of this study, RED and DT are compared by observing their effects on two important indicators of congestion: end-to-end delay and delay variation. This comparison reveals that the performances of RED and DT vary according to the level of global congestion: under low congestion conditions, when packet losses caused by congestion are unlikely, DT outperforms RED; while under high congestion, RED is superior to DT. The SOM based approach takes into account the variations in the global congestion levels and makes decisions to optimise congestion avoidance. A centralized observation unit is designed for monitoring global congestion levels in autonomous IP networks. A traffic flow is generated between each router and the observation unit so as to follow the changes in the global congestion level. For this purpose, IP routers are specialized to send packets carrying queue length information to the observation unit. A SOM based decision mechanism is used by the observation unit, to make predictions on the future congestion behavior of the network and inform the routers. Routers use this information to update their congestion avoidance behavior, as their ability to update their RED parameters is enhanced by the congestion notifications sent by the observation unit. In this work, multiple simulations are undertaken in order to test the performance of the proposed SOM-based method. A considerable improvement is observed from the point of view of end-to-end delays and delay variations, by comparison with DT and RED as used in recent IP networks.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public