a b s t r a c tSome necessary and sufficient conditions are obtained for the controllability and observability of a networked system with linear time invariant (LTI) dynamics. The topology of this system is fixed but arbitrary, and every subsystem is permitted to have different dynamics. These conditions essentially depend only on transmission zeros of every subsystem and the subsystem connection matrix, which makes them attractive in the analysis and synthesis of a large-scale networked system. As an application, these conditions are utilized to characterize systems whose steady estimation accuracy with the distributed predictor of Zhou (2013) is equal to that of the lumped Kalman filter. It has been made clear that to guarantee this equivalence, the steady update gain matrix of the Kalman filter must be block diagonal.

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BackgroundLong noncoding RNAs (lncRNAs) have been shown to be involved in the development and progression of lung cancer. However, the roles of lncRNAs in lung cancer are not well understood.Methodology/Principal FindingsWe used a high-throughput microarray to compare the lncRNA and messenger RNA (mRNA) expression profiles in lung adenocarcinoma and normal tissue (NT) samples. Several candidate adenocarcinoma-associated lncRNAs were verified by real-time quantitative reverse transcription polymerase chain reaction (PCR) analysis. Using abundant and varied probes, we were able to assess 30,586 lncRNAs and 26,109 mRNAs in our microarray. We found that 2,420 lncRNAs and 1,109 mRNAs were differentially expressed (≥2-fold change) in lung adenocarcinoma samples and NT, indicating that many lncRNAs were significantly upregulated or downregulated in lung adenocarcinoma. We also found, via quantitative PCR, that 19 lncRNAs were aberrantly expressed in lung adenocarcinoma compared with matched histologically normal lung tissues. Among these, LOC100132354 and RPLP0P2 were the most aberrantly expressed lncRNAs, as estimated by quantitative PCR in 100 pairs of lung adenocarcinoma and NT samples.Conclusions/SignificanceOur study ascertained the expression patterns of lncRNAs in lung adenocarcinoma by microarray. The results revealed that many lncRNAs were differentially expressed in lung adenocarcinoma tissues and NT, suggesting that they may play a key role in tumor development.

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A recursive state estimation procedure is derived for a linear time varying system with both parametric uncertainties and stochastic measurement droppings. This estimator has a similar form as that of the Kalman filter with intermittent observations, but its parameters should be adjusted when a plant output measurement arrives. A new recursive form is derived for the pseudo-covariance matrix of estimation errors, which plays important roles in analyzing its asymptotic properties. Based on a Riemannian metric for positive definite matrices, some necessary and sufficient conditions have been obtained for the strict contractiveness of an iteration of this recursion. It has also been proved that under some controllability and observability conditions, as well as some weak requirements on measurement arrival probability, the gain matrix of this recursive robust state estimator converges in probability one to a stationary distribution.Numerical simulation results show that estimation accuracy of the suggested procedure is more robust against parametric modelling errors than the Kalman filter.

This paper studies structural controllability for a networked dynamic system (NDS), in which each subsystem may have different dynamics, and unknown parameters may exist both in subsystem dynamics and in subsystem interconnections. In addition, subsystem parameters are parameterized by a linear fractional transformation (LFT). It is proven that controllability keeps to be a generic property for this kind of NDSs. Some necessary and sufficient conditions are then established respectively for them to be structurally controllable, to have a fixed uncontrollable mode, and to have a parameter dependent uncontrollable mode, under the condition that each subsystem interconnection link can take a weight independently. These conditions are scalable, and in their verifications, all arithmetic calculations are performed separately on each subsystem. In addition, these conditions also reveal influences on NDS controllability from subsystem input-output relations, subsystem uncontrollable modes and subsystem interconnection topology. Based on these observations, the problem of selecting the minimal number of subsystem interconnection links is studied under the requirement of constructing a structurally controllable NDS. A heuristic method is derived with some provable approximation bounds and a low computational complexity.

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