Both, severe hypo- or hyperthyroidism may alter hemodynamic parameters. The aim of our study was to ascertain, whether also distinct changes within normal range of free thyroxine (fT4) would be associated with an impairment of left ventricle function in patients with chronic heart failure. Hundred-forty-eight patients (m121, f27, mean age 63.8±1.14 years) with chronic heart failure, fT4 levels within the normal range (9-22 pmol/l) and without thyrostatics or substitution treatment. Degree of heart failure was quantified by plasma B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP). Patients with fT4 in the range 11.9-14.6 pmol/l [optimal, 2nd-3th quintile] had significantly lower NT-proBNP (718±70.4 pg/ml), than those with fT4<11.8 [low-normal, bottom quintile](1236±223.6 pg/ml; p<0.03) and those with fT4 over 14.6 pmol/l [high-normal, top two quintiles] (1192±114.9 pg/ml; p<0.0002). These differences remain significant, also if adjusted for age, gender and other confounders; adjusted odds ratio was 1.30 (1.05-1.59) for optimal vs. low-normal and 1.27 (1.04-1.55) for optimal vs. high-normal. Similar statistical differences were also found in BNP, but only when optimal and high-normal fT4 ranges were compared. In conclusion, the severity of heart failure seems to be also influenced by only mild deviations of fT4 concentrations from optimal levels., O. Mayer Jr, J. Šimon, J. Čech, H. Rosolová, J. Hrbková, R. Pikner, L. Trefil., and Obsahuje bibliografii a bibliografické údaje
By using Mawhin’s continuation theorem, the existence of even solutions with minimum positive period for a class of higher order nonlinear Duffing differential equations is studied.
This paper focuses on the multi-objective filtering of multirate time-varying systems with random sensor saturations, where both the variance-constrained index and the H∞ index are employed to evaluate the filtering performance. According to address issues, the high-frequency period of the internal state of the system is nondestructively converted to the low-frequency period, which determined by the measurement devices. Then the saturated output of multiple sensors is modeled as a sector bounded nonlinearity. At the same time, in order to reduce the communication frequency between sensors and filters, a communication scheduling rule is designed by the utilization of an event-triggered mechanism. By means of random analysis technology, the sufficient conditions are given to guarantee the preset H∞ performance and variance constraint performance indexes of the system, and then the solution of the desired filter is obtained by using linear matrix inequalities. Finally, the validity and effectiveness of the proposed filter scheme are verified by numerical simulation.
This paper addresses event-triggered control cyber-physical systems under asynchronous denial of service attacks. First, a general attack model is given, which allows us to conveniently model the asynchronous denial of service attacks within measurement and control channels in a unified framework. Then, under a delicate event triggered communication mechanism, a refined switching control mechanism is proposed to account for various attack intervals and non-attack intervals. Furthermore, sufficient conditions are derived for guaranteing the input to state stability (ISS) of the resulting closed-loop system. Finally, a simulation example of unmanned ground vehicle (UGV) is given to demonstrate the validity of the proposed main results.
This paper is concerned with the problem of H∞ event-triggered output feedback control of discrete time piecewise-affine systems. Relying on system outputs, a piecewise-affine triggering condition is constructed to release communication burden. Resorting to piecewise Lyapunov functional and robust control techniques, sufficient conditions are built to ensure the closed-loop systems to be asymptotically stable with the prescribed H∞ performance. By utilizing a separation strategy, the static output feedback controller is solved by means of linear matrix inequalities. The validity of the proposed method are demonstrated by numerical examples.
This paper investigates the distributed event-triggered cooperative output regulation problem for heterogeneous linear continuous-time multi-agent systems (MASs). To eliminate the requirement of continuous communication among interacting following agents, an event-triggered adaptive distributed observer is skillfully devised. Furthermore, a class of closed-loop estimators is constructed and implemented on each agent such that the triggering times on each agent can be significantly reduced while at the same time the desired control performance can be preserved. Compared with the existing open-loop estimators, the proposed estimators can provide more accurate state estimates during each triggering period. It is further shown that the concerned cooperative output regulation problem can be effectively resolved under the proposed control scheme and the undesirable Zeno behavior can be excluded. Finally, the effectiveness of the proposed results is verified by numerical simulations.
Following the study of sharp domination in effect algebras, in particular, in atomic Archimedean MV-effect algebras it is proved that if an atomic MV-effect algebra is {\it uniformly Archimedean} then it is sharply dominating.