An Underwater Source Localization Method Using Bearing Measurements.

Angle-of-arrival (AOA) measurements are often used in underwater acoustical localization. Different from the traditional AOA model based on azimuth and elevation measurements, the AOA model studied in this paper uses bearing measurements. It is also often used in the Ultra-Short Baseline system (USBL). However, traditional acoustical localization needs additional range information. If the range information is unavailable, the closed-form solution is difficult to obtain only with bearing measurements. Thus, a localization closed-form solution using only bearing measurements is explored in this article. A pseudo-linear measurement model between the source position and the bearing measurements is derived, and considering the nonlinear relationship of the parameters, a weighted least-squares optimization equation based on multiple constraints is established. Different from the traditional two-step least-squares method, the semidefinite programming (SDP) method is designed to obtain the initial solution, and then a bias compensation method is proposed to further minimize localization errors based on the SDP result. Numerical simulations show that the performance of the proposed method can achieve Cramer-Rao lower bound (CRLB) accuracy. The field test also proves that the proposed method can locate the source position without range measurements and obtain the highest positioning accuracy.

A Robust INS/USBL/DVL Integrated Navigation Algorithm Using Graph Optimization.

The Autonomous Underwater Vehicle (AUV) is usually equipped with multiple sensors, such as an inertial navigation system (INS), ultra-short baseline system (USBL), and Doppler velocity log (DVL), to achieve autonomous navigation. Multi-source information fusion is the key to realizing high-precision underwater navigation and positioning. To solve the problem, a fusion scheme based on factor graph optimization (FGO) is proposed. Due to multiple iterations and joint optimization of historical data, FGO could usually show a better performance than the traditional Kalman filter. In addition, considering that USBL and DVL are usually heavily influenced by the environment, outliers are often present. A robust integrated navigation algorithm based on a maximum correntropy criterion and FGO scheme is proposed. The proposed algorithm solves the problem of multi-sensor fusion and non-Gaussian noise. Numerical simulations and field tests demonstrate that the proposed FGO scheme shows a better performance and robustness than the traditional Kalman filter. Compared with the traditional Kalman filtering, the positioning accuracy is improved by 5.3%, 9.1%, and 5.1% in the east, north, and height directions. It can realize a more accurate navigation and positioning of underwater multi-sensors.

Bergamottin exerts anticancer effects on human colon cancer cells via induction of apoptosis, G2/M cell cycle arrest and deactivation of the Ras/Raf/ERK signalling pathway.

Introduction: Accumulating evidence has shown the potential of bergamottin as an anticancer agent. The present study was undertaken to evaluate the anticancer affects of bergamottin (µM) against colon cancer cells. Material and methods: Antiproliferative effects were evaluated by WST-1 cell viability assay. Apoptotic effects were studied by DAPI and Annexin V/PI staining. Cell cycle analysis was carried out by flow cytometry. Transwell assay was used to study the effects on cell invasion. Protein expression was estimated by the western blot method. Results: The results showed that bergamottin suppresses the proliferation of all the human colon cancer cell lines. Nonetheless, the growth inhibitory effects of bergamottin on the HT-29 and RKO cells were more significant (IC50, 12.5 µM). The anticancer effects of bergamottin on the HT-29 and RKO cells were mainly due to apoptosis. Bergamottin could considerably increase the expression of Bax and reduce the expression Bcl-2. The cleavage of caspase-3, 8 and 9 was also enhanced upon bergamottin treatment of the colon cancer cells. Flow cytometric analysis showed that bergamottin also induced G2/M cell cycle arrest of the HT-29 and RKO cells. Additionally, bergamottin could also suppress the invasion of HT-29 and RKO cells. The Raf/MEK/ERK pathway is regarded as one of the essential pathways involved in the development and progression of cancers. Herein, it was observed that bergamottin could concentration dependently block this pathway in colon cancer cells. In vivo study revealed that bergamottin could also suppress the growth of tumours in xenografted mice models. Conclusions: Taken together, bergamottin suppresses the proliferation of colon cancer cells and may be utilised in the development of chemotherapy for colon cancer.

A new method for determination of uric acid by the lactic acid-acetone-BrO(3)(-)-Mn(2+)-H(2)SO(4) oscillating reaction using the analyte pulse perturbation technique.

A new analytical method for the determination of uric acid (UA) by the perturbation of UA on the Belousov-Zhabotinsky oscillating reaction is proposed. The method is based on the linear relationship between the changes in the oscillating period and the concentration of UA. The calibration curve is linear over the range of 2.0 x 10(-5) to 5.0 x 10(-4)M, with a detecting limit of 3.28 x 10(-6)M. The method features good precision (R.S.D.: 3.59%) and excellent throughput (10samplesh(-1)). The possible mechanism of the perturbation of UA on the oscillating reaction is discussed.