Multiple Model Adaptive Nonlinear Observer of Dynamic Positioning Ship

Considering the filtering problem of dynamic positioning (DP) ship for the slowly varying sea state, a multiple model adaptive observer (MMAO) for dynamic positioning ship is presented. The MMAO consists of a bank of nonlinear subobserver and a dynamic weighting signal generator, in which each sub-observer is designed based on different peak frequency of wave spectrum model. To improve the performance of the observer, subobserver using the measurement of position, velocity, and acceleration is used to update the estimated velocity of ship. The observer parameters are optimized using particle swarm optimization (PSO). Finally, the method is verified effective by the computer simulation

Estimation of Observer Parameters for Dynamic Positioning Ships

Considering the problem of dynamic positioning systems for the slowly varying disturbances, a parametrically adaptive observer is presented. The peak frequency of observer is adjusted on-line by autoregressive (AR) spectral estimation; other parameters of observer are optimized using particle swarm optimization (PSO). The peak frequency can be calculated by spectral analysis of the pitch, roll, and heave measurements. In the spectral estimation, Levinson-Durbin algorithm is used to solve the Yule-Walker equations. Finally, the computer simulation is given to demonstrate the effectiveness of the proposed method

MiR-3646 accelerates inflammatory response of Ang II-induced hVSMCs via CYP2J2/EETs axis in hypertension model

Background Inflammatory response of human vascular smooth muscle cells (hVSMCs) is a driving factor in hypertension progression. It has been reported that miR-3646 was significantly up-regulated in serum samples from patients with coronary artery disease and acute myocardial infarction mice. However, its role and underlying molecular mechanism related to inflammatory response of angiotensin II (Ang II)-induced hVSMCs remain unclear. Objective We aimed to explore the potential molecular mechanisms related to inflammatory response of angiotensin II (Ang II)-induced hVSMCs. Methods Ang II–induced hypertension model was established after hVSMCs treated with 1 μM Ang II at 24 h. The interaction between microRNA 3646 (miR-3646) and cytochrome P450 2J2 (CYP2J2) was assessed by dual-luciferase reporter gene assay. MTS assay, Lipid Peroxidation MDA Assay Kit, ELISA, Western blot, and qRT-PCR were performed to examine viability, malondialdehyde (MDA) level, inflammatory cytokine levels, and the level of genes and proteins. Results Our findings illustrated that miR-3646 was up-regulated but CYP2J2 was down-regulated in Ang II–induced hVSMCs. Mechanically, miR-3646 negatively targeted to CYP2J2 in Ang II–induced hVSMCs. These findings indicated that miR-3646 regulated inflammatory response of Ang II–induced hVSMCs via targeting CYP2J2. Moreover, functional researches showed that CYP2J2 overexpression alleviated inflammatory response of Ang II–induced hVSMCs via epoxyeicosatrienoic acids/peroxisome proliferator-activated receptor-γ (EETs/PPARγ) axis, and miR-3646 aggravated inflammatory response of Ang II–induced hVSMCs via mediating CYP2J2/EETs axis. Conclusion MiR-3646 accelerated inflammatory response of Ang II–induced hVSMCs via CYP2J2/EETs axis. Our findings illustrated the specific molecular mechanism of miR-3646 regulating hypertension

Most medical practices are not parachutes: a citation analysis of practices felt by biomedical authors to be analogous to parachutes

BACKGROUND:In a 2003 paper in BMJ, the authors made the tongue-in-cheek observation that there are no randomized controlled trials (RCTs) of parachutes. This paper has been widely read, cited and used to argue that RCTs are impractical or unnecessary for some medical practices. We performed a study to identify and evaluate claims that a medical practice is akin to a parachute. METHODS:Using Google Scholar, we identified all citations to the 2003 paper. We searched for claims that a specific practice was akin to a parachute. For each practice, we identified the desired outcome of the practice, and searched Google Scholar and ClinicalTrials.gov for RCTs that were conducted, ongoing, halted, planned or unpublished. RESULTS:Of 822 articles citing the original paper, 35 (4.1%) argued that a medical practice was akin to a parachute. Eighteen of the 35 (51%) concerned mortality or live birth, and 17 (49%) concerned a lesser outcome. For 22 practices (63%), we identified 1 or more RCTs: in 6 cases (27%), the trials showed a statistically significant benefit of the practice; in 5 (23%), the trials rejected the practice; in 5 (23%), the trials had mixed results; in 2 (9%), the trials were halted; and in 4 (18%), the trials were ongoing. Effect size was calculated for 5 of the 6 practices for which RCTs gave positive results, and the absolute risk reduction ranged from 11% to 30.8%, corresponding to a number needed to treat of 3-9. INTERPRETATION:Although there is widespread interest regarding the BMJ paper arguing that randomized trials are not necessary for practices of clear benefit, there are few analogies in medicine. Most parachute analogies in medicine are inappropriate, incorrect or misused