In this paper the regulator and filter algebraic Riccati equations, corresponding to the steady state optimal control and filtering of weakly coupled linear discrete stochastic systems are solved in terms of reduced-order sub problems by using the eigenvector approach. The eigenvector method outperforms iterative methods (fixed point iterations, Newton method) of solutions to reduced-order sub problems in case of higher level of coupling between subsystems. In such cases the iterative methods could fail to produce solutions of the corresponding algebraic Riccati equations.

Riboswitches harness the structural and dynamic sophistication of RNA to coordinate specific ligand recognition with changes in gene expression. Design of molecules to manipulate riboswitch responses relies on our understanding of their RNA−ligand interactions. Here we demonstrate that for the adenine (A) riboswitch (ARNA) these interactions are highly dynamic. Given that 2-aminopurine (Ap) mimics A in its interactions with ARNA, we use the fluorescence lifetime of Ap to interrogate individual Ap-ARNA conformers (dynamic exchange times > ∼10 ns). Counter to predictions of two state and induced fit models, the ligand-bound A riboswitch is not a single, highly ordered structure:  We detect at least three distinct Ap-ARNA conformers in ensemble solution. Their distribution indicates that they are not high-energy RNA folding intermediates but are instead energetically similar (ΔG < 1 kcal mol-1) conformers whose thermal stability, ligand, and Mg2+ binding affinity differ substantially. Our experimental charac...

The aim of this study was to analyze the Transit time flow measurement (TTFM) experience in the first 1000 CABG operations. First 1000 patients had coronary artery bypass grafting (CABG) performed in Cardiovascular Clinic, University Clinical Centre Tuzla, Bosnia and Herzegovina, between September, 1998 and September, 2003. CABG without use of cardiopulmonary bypass (CPB)-(OPCAB) was used as the preferential surgical method both because this method is reported to have equal or better results than CABG with use of CPB (ONCAB), and because of the significant cost savings realized. TTFM was routinely used in all grafts as a quality assurance measure. Criteria for a poor functioning graft were: low mean flow (MF), pulsatility index (PI) above 5 and a poor diastolic flow pattern. When no reversible cause of poor TTFM results were identified the graft was revised. A total of 1394 grafts in OPCAB group and 1478 in ONCAB group were performed. A total of 38 grafts (2,72%) in 37 patients (7,07%) were revised in OPCAB group, and 26 grafts (1,75%) in 26 patients (5,45%) in ONCAB group. 1 patient in OPCAB group needed 2 graft revisions. Graft revisions were more common in OPCAB, but with no significant difference (p=0,1035). The most frequently revised graft was LAD graft in both groups. Although the percentage of grafts revised are relatively low, it is still very important to record TTFM. More than 5% of patients in both groups needed graft revision. Although TTFM does not guarantee that grafts will stay open for a prolonged period of time we certainly believe that grafts that are occluded at the time of surgery will continue to stay occluded. TTFM is especially critical in OPCAB surgery where the technical challenge of grafting is higher then in ONCAB.