Prescribed Performance Control for Two-axis Optronic Stabilized Platform

Aiming at improving the tracking and stabilizing performance of two-axis optronic stabilized platform with Stribeck friction and uncertain velocity disturbance, a prescribed performance control strategy with unknown initial errors is designed. By designing a new performance function, the limit of traditional prescribed control that the initial error has to be known accurately is broken through. The strategy possesses strong robustness against unknown disturbance, and the state error is restrained to a predefined arbitrary small residual. It is guaranteed that the closed-loop system is uniformly ultimately bounded. The simulation results demonstrate the effectiveness of proposed strategy

Attitude Controller Design with State Constraints for Kinetic Kill Vehicle Based on Barrier Lyapunov Function

An adaptive attitude controller is designed based on Barrier Lyapunov Function (BLF) to meet the state constraints caused by side window detection. Firstly, the attitude controller is designed based on the BLF, but the stabilization function is complex and its time derivative will cause “differential explosion”. Therefore, Finite-time-convergent Differentiator (FD) is used to estimate the first derivative of the stabilization function. If the tracking error is outside the BLF's convergence domain, BLF controller cannot guarantee the error global convergence. Sliding mode controller (SMC) is used to make the system's error converge to set domain, and then the BLF controller could be used to ensure that the output constraint is not violated. Uncertainties and unknown time-varying disturbances usually make the control precision worse and Nonlinear Disturbance Observer (NDO) is designed for estimation and compensation uncertainties and disturbances. The pseudo rate modulator (PSR) is used to shape the continuous control command to pulse or on-off signals to meet the requirements of the thruster. Numerical simulations show that the proposed method can achieve state constraints, pseudo-linear operation, and high accuracy

Prescribed Performance Control for Two-axis Optronic Stabilized Platform

Aiming at improving the tracking and stabilizing performance of two-axis optronic stabilized platform with Stribeck friction and uncertain velocity disturbance, a prescribed performance control strategy with unknown initial errors is designed. By designing a new performance function, the limit of traditional prescribed control that the initial error has to be known accurately is broken through. The strategy possesses strong robustness against unknown disturbance, and the state error is restrained to a predefined arbitrary small residual. It is guaranteed that the closed-loop system is uniformly ultimately bounded. The simulation results demonstrate the effectiveness of proposed strategy

Prefrontal cortical dopamine deficit may cause impaired glucose metabolism in schizophrenia

Abstract The brain neurotramsmitter dopamine may play an important role in modulating systemic glucose homeostasis. In seven hundred and four drug- naïve patients with first-episode schizophrenia, we provide robust evidence of positive associations between negative symptoms of schizophrenia and high fasting blood glucose. We then show that glucose metabolism and negative symptoms are improved when intermittent theta burst stimulation (iTBS) on prefrontal cortex (PFC) is performed in patients with predominantly negative symptoms of schizophrenia. These findings led us to hypothesize that the prefrontal cortical dopamine deficit, which is known to be associated with negative symptoms, may be responsible for abnormal glucose metabolism in schizophrenia. To explore this, we optogenetically and chemogenetically inhibited the ventral tegmental area (VTA)-medial prefrontal cortex (mPFC) dopamine projection in mice and found both procedures caused glucose intolerance. Moreover, microinjection of dopamine two receptor (D2R) neuron antagonists into mPFC in mice significantly impaired glucose tolerance. Finally, a transgenic mouse model of psychosis named Disc1tr exhibited depressive-like symptoms, impaired glucose homeostasis, and compared to wild type littermates reduced D2R expression in prefrontal cortex

pH-Triggered and Enhanced Simultaneous Photodynamic and Photothermal Therapy Guided by Photoacoustic and Photothermal Imaging

Developing smart photosensitizers sensitively responding to tumor-specific signals for reduced side effects and enhanced anticancer efficacy is a major challenge for tumor phototherapy. Herein, a pH-sensitive photosensitizer has been synthesized through introducing a pH-sensitive receptor (dimethylaminophenyl unit) onto the aza-BODIPY core (abbreviated as NAB). Through enveloping hydrophobic NAB with amphiphilic DSPE-mPEG₂₀₀₀, NAB nanoparticles (NPs, diameter ∼ 30 nm) with strong near-infrared absorption (∼792 nm) are obtained. NAB NPs can be activated in weak acidic environment to give high rate of reactive oxygen species (ROS) generation and enhanced photothermal effect. NAB NPs can selectively accumulate in the lysosomes of tumor cells and subsequently activate under the acidic microenvironment of lysosome (pH 5.0) to produce ROS for photodynamic therapy, due to switch-off of the photoinduced electron transfer (PET) pathway. In vivo, pH-enhanced photoacoustic imaging (PAI) and photothermal imaging (PTI) confirm that NAB NPs can selectively aggregate in the tumor, and the tumor growth can be effectively inhibited under xenon lamp irradiation through synergistic phototherapy (photodynamic and photothermal therapy, PDT/PTT). Furthermore, based on PAI signal and terminal elimination half-life (<i>T</i>_1/2) obtained by pharmacokinetic experiment, it is concluded that the NAB NPs can be rapidly metabolized. The pH-sensitive NAB NPs offer a new possibility toward PAI and PTI guided synergistic phototherapy