Deep Koopman Learning of Nonlinear Time-Varying Systems

A data-driven method is developed to approximate an nonlinear time-varying system (NTVS) by a linear time-varying system (LTVS), based on Koopman Operator and deep neural networks. Analysis on the approximation error in system states of the proposed method is investigated. It is further shown by simulation on a simple NTVS that the resulted LTVS approximate the NTVS very well with small approximation errors in states. Furthermore, simulations on a cartpole further show that optimal controller developed based on the achieved LTVS works very well to control the original NTVS

Cortical morphological heterogeneity of schizophrenia and its relationship with glutamatergic receptor variations

Abstract Background Recent genetic evidence implicates glutamatergic-receptor variations in schizophrenia. Glutamatergic excess during early life in people with schizophrenia may cause excitotoxicity and produce structural deficits in the brain. Cortical thickness and gyrification are reduced in schizophrenia, but only a subgroup of patients exhibits such structural deficits. We delineate the structural variations among unaffected siblings and patients with schizophrenia and study the role of key glutamate-receptor polymorphisms on these variations. Methods Gaussian Mixture Model clustering was applied to the cortical thickness and gyrification data of 114 patients, 112 healthy controls, and 42 unaffected siblings to identify subgroups. The distribution of glutamate-receptor (GRM3, GRIN2A, and GRIA1) and voltage-gated calcium channel (CACNA1C) variations across the MRI-based subgroups was studied. The comparisons in clinical symptoms and cognition between patient subgroups were conducted. Results We observed a “hypogyric,” “impoverished-thickness,” and “supra-normal” subgroups of patients, with higher negative symptom burden and poorer verbal fluency in the hypogyric subgroup and notable functional deterioration in the impoverished-thickness subgroup. Compared to healthy subjects, the hypogyric subgroup had significant GRIN2A and GRM3 variations, the impoverished-thickness subgroup had CACNA1C variations while the supra-normal group had no differences. Conclusions Disrupted gyrification and thickness can be traced to the glutamatergic receptor and voltage-gated calcium channel dysfunction respectively in schizophrenia. This raises the question of whether MRI-based multimetric subtyping may be relevant for clinical trials of agents affecting the glutamatergic system

Thymosin alpha 1 in the prevention of infected pancreatic necrosis following acute necrotising pancreatitis (TRACE trial): protocol of a multicentre, randomised, double-blind, placebo-controlled, parallel-group trial

Introduction Infected pancreatic necrosis (IPN) and its related septic complications are the major causes of death in patients with acute necrotising pancreatitis (ANP). Therefore, the prevention of IPN is of great clinical value, and immunomodulatory therapy with thymosin alpha 1 may be beneficial. This study was designed to test the hypothesis that the administration of thymosin alpha 1 during the acute phase of ANP will result in a reduced incidence of IPN. Methods and analysis This is a randomised, multicentre, double-blind, placebo-controlled study. 520 eligible patients with ANP will be randomised in a 1:1 ratio to receive either the thymosin alpha 1 or the placebo using the same mode of administration. The primary endpoint is the incidence of IPN during the index admission. Most of the secondary endpoints will be registered within the index admission including in-hospital mortality, the incidence of new-onset organ failure and new-onset persistent organ failure (respiration, cardiovascular and renal), receipt of new organ support therapy, requirement for drainage or necrosectomy, bleeding requiring intervention, human leucocyte antigens-DR(HLA-DR) on day 0, day 7, day 14, and so on and adverse events. Considering the possibility of readmission, an additional follow-up will be arranged 90 days after enrolment, and IPN and death at day 90 will also be served as secondary outcomes. Ethics and dissemination This study was approved by the ethics committee of Jinling Hospital, Nanjing University (Number 2015NZKY-004-02). The thymosin alpha 1 in the prevention of infected pancreatic necrosis following acute necrotising pancreatitis(TRACE) trial was designed to test the effect of a new therapy focusing on the immune system in preventing secondary infection following ANP. The results of this trial will be disseminated in peer-reviewed journals and at scientific conferences. Trial registration number ClinicalTrials.gov Registry (NCT02473406)

Microfluidics Facilitates the Development of Single-Cell RNA Sequencing

Single-cell RNA sequencing (scRNA-seq) technology provides a powerful tool for understanding complex biosystems at the single-cell and single-molecule level. The past decade has been a golden period for the development of single-cell sequencing, with scRNA-seq undergoing a tremendous leap in sensitivity and throughput. The application of droplet- and microwell-based microfluidics in scRNA-seq has contributed greatly to improving sequencing throughput. This review introduces the history of development and important technical factors of scRNA-seq. We mainly focus on the role of microfluidics in facilitating the development of scRNA-seq technology. To end, we discuss the future directions for scRNA-seq

Research on Direct Yaw Moment Control of Electric Vehicles Based on Electrohydraulic Joint Action

To solve the problem of lateral instability of the vehicle caused by insufficient lateral force of the tires due to the insufficient torque provided by the motor to the tire when the vehicle turns sharply or avoids obstacles in an emergency, a layered control method is used to design a lateral stability control system. The upper decision layer selects the yaw rate and the sideslip angle of the center of mass as the control variables and uses the joint state deviation of the yaw rate and the sideslip angle of the center of mass and the rate of change of the deviation as the input of the sliding mode variable structure controller to calculate the additional yaw moment required to maintain vehicle stability. The lower torque distribution layer realizes the distribution of torque through the electro-hydraulic coordinated control method: the torque distribution rule based on real-time load transfer calculates the torque corresponding to the control wheel and generates the torque through the hub motor and transmits it to the wheel. When the torque output from the motor cannot provide sufficient torque for the vehicle, hydraulic braking is used as a compensating control, and the difference between the required yaw torque and the motor-generated yaw torque is used as the required torque for hydraulic control to calculate the wheel cylinder pressure required to brake the wheels. Based on the joint simulation model of MATLAB/Simulink and Carsim, the sine and double shift line working condition are selected for stability simulation experiments. From the simulation results, it can be seen that the yaw rate and sideslip angle of the center of mass of the vehicle with sliding mode control and electro-hydraulic coordinated control almost coincide with the ideal value curve, which are both smaller than the output parameters of the uncontrolled vehicle. From the perspective of the motor output torque, compared with pure motor control, the effect of electro-hydraulic coordinated control is better, and the hydraulic system can compensate for the braking torque in time and enhance the lateral stability of the vehicle. The designed control strategy can make the yaw rate and the sideslip angle of the center of mass of the vehicle follow the reference value better, which can effectively avoid the vehicle sideslip and instability and improve the vehicle yaw stability and driving safety. However, due to the limitations of experimental equipment, the proposed method could not be applied to the real vehicle test. The real vehicle test can better test the control effect of the proposed method

Preparation of Ti-Doped ZnO/Bi₂O₃ Nanofilm Heterojunction and Analysis of Microstructure and Photoelectric Properties

Ti-doped ZnO (TZO) and Bi2O3 thin films were designed and deposited by magnetron sputtering successively on ITO glass substrate to form a Ti-doped ZnO/Bi2O3 (TZO/Bi2O3) heterojunction. Microstructure and photoelectric properties of TZO, Bi2O3, and TZO/Bi2O3 films were tested and characterized. The results showed that TZO film with a hexagonal wurtzite structure was preferentially grown along the crystal plane (002), had a good crystallization state, and was an N-type semiconductor film with high transmittance (90%) and low resistivity (4.68 × 10−3 Ω·cm). However, the Bi2O3 film sputtered in an oxygen-containing atmosphere and was a polycrystalline film that was preferentially grown along the crystal plane (111). It had a lower crystallization quality than TZO film and was a P-type semiconductor film with low transmittance (68%) and high resistance (1.71 × 102 Ω·cm). The I–V curve of TZO/Bi2O3 composite films showed that it had an obvious heterojunction rectification effect, which indicates that the PN heterojunction successfully formed in TZO/Bi2O3 films

Silica Nanotubes Decorated by pH-Responsive Diblock Copolymers for Controlled Drug Release

A novel nanocontainer, which has silica nanotube (SNT) core and pH-sensitive polymer shell attaching on the exterior surface of silica nanotube, is presented in this paper. Polymer nanorods, which are conveniently fabricated though polymerization-induced self-assembly and reorganization method, are used as templates for the deposition of silica to fabricate hybrid nanorods. Calcination of as-synthesized silica hybrid nanorods leads to hollow SNTs. SNTs are functionalized with reversible addition–fragmentation chain transfer (RAFT) agent, then surface RAFT polymerization is conducted to get poly­(2-(diethylamino)­ethyl methacrylate)-<i>b</i>-poly­(oligo­(ethylene glycol) methacrylate)-coated SNTs (SNT-PDEAEMA-<i>b</i>-POEGMA). Doxorubicin (DOX) can be encapsulated in SNT-PDEAEMA-<i>b</i>-POEGMA, and controlled release of loaded DOX is achieved by adjusting pH of the medium. In vitro cell viability and cellular internalization study confirm the potential application of this nanocontainer in drug and gene delivery

Plasma Osteoprotegerin Correlates with Stroke Severity and the Occurrence of Microembolic Signals in Patients with Acute Ischemic Stroke

Background. Instability of atherosclerotic plaques is associated with the occurrence of stroke. Microembolic signals (MESs) are an indicator of unstable plaque. A relationship between plasma osteoprotegerin (OPG) and ischemic stroke has already been identified. The aim of this study was to investigate whether plasma OPG levels have a relationship with MESs and to evaluate the feasibility of OPG as a biomarker of stroke severity and occurrence of MESs. Methods. Our study consisted of 127 patients with large artery atherosclerosis stroke and 56 controls. Patients were classified into subgroups based on stroke severity and the occurrence of MESs. MES-monitoring was performed for 60 min using transcranial Doppler within 72 h of stroke onset. Stroke severity at admission was assessed by the National Institutes of Health Stroke Scale. Results. Plasma OPG levels were significantly associated with stroke, MESs, and stroke severity at admission (adjusted OR [95% CI]: 1.002 [1.001–1.003] p<0.001; 1.002 [1.001–1.003] p=0.001; 1.001 [1.000–1.002] p=0.028). When plasma OPG levels were used to determine the stroke severity, the area under the receiver-operating characteristic curve (AUC) was 0.734 (95% CI: 0.625-0.843) based on a cutoff value of 1998.44 pg/ml; the sensitivity and specificity of this test were 80.6% and 65.6%, respectively. Furthermore, when the levels of OPG were used to distinguish the presence of MESs, the AUC was 0.766 (95% CI: 0.672-0.860); the cutoff value was 2107.91 pg/ml. The sensitivity of this cutoff value was 68.8% and the specificity was 73.7%. Conclusions. Plasma OPG levels correlate with stroke severity and the occurrence of MESs

Comparative Assessment of the Antioxidant Activities among the Extracts of Different Parts of Clausena lansium (Lour.) Skeels in Human Gingival Fibroblast Cells

Clausena lansium (Lour.) Skeels (wampee) is an outstanding natural plant with medicinal properties. The aim of this study was to compare the cytoprotective effects of four parts of wampee under oxidative stress. The aqueous extracts of leaf, peel, pulp, and seed were tested for the proliferation effects on human gingival fibroblast (HGF) cells and the protective effects in the hydrogen peroxide-induced HGF model. Furthermore, the total glutathione assay and identification of rutin by high-performance liquid chromatography were carried out to attempt to determine whether the cytoprotective effects were related to the total glutathione (GSH) stability and rutin content. The results showed that all of the extracts had no cytotoxicity to HGF at tested concentrations ranging from 50 to 5000 μg/ml during 24 h, and the leaf, pulp, and seed extracts increased proliferation of HGF at relatively high concentrations. All the extracts except for the seed extract significantly decreased the production of reactive oxygen species, and the peel extracts exhibited the most effective antioxidant effect. The leaf extract had the highest anticytotoxicity and GSH stabilization effect in the HGF challenged with hydrogen peroxide. In addition, the relative content of rutin in peel and leaf extracts was higher than that in pulp and seed. The results of GSH assay and rutin identification suggest that different cellular protective effects among the four parts of wampee are partially related to the GSH stabilization and rutin content. These findings provide a scientific basis for the antioxidant effect-related biological activities of wampee extracts