Closed-loop Structure Research Articles

Circular RNAs Involve in Immunity of Digestive Cancers From Bench to Bedside: A Review.

The immune system plays a complex role in tumor formation and development. On the one hand, immune surveillance can inhibit the growth of tumors; on the other hand, immune evasion of tumors can create conditions conducive for tumor development and growth. CircRNAs are endogenous non-coding RNAs with a covalently closed loop structure that are abundantly expressed in eukaryotic organisms. They are characterized by stable structure, rich diversity, and high evolutionary conservation. In particular, circRNAs play a vital role in the occurrence, development, and treatment of tumors through their unique functions. Recently, the incidence and mortality of digestive cancers, especially those of gastric cancer, colorectal cancer, and liver cancer, have remained high. However, the functions of circRNAs in digestive cancers immunity are less known. The relationship between circRNAs and digestive tumor immunity is systematically discussed in our paper for the first time. CircRNA can influence the immune microenvironment of gastrointestinal tumors to promote their occurrence and development by acting as a miRNA molecular sponge, interacting with proteins, and regulating selective splicing. The circRNA vaccine even provides a new idea for tumor immunotherapy. Future studies should be focused on the location, transportation, and degradation mechanisms of circRNA in living cells and the relationship between circRNA and tumor immunity. This paper provides a new idea for the diagnosis and treatment of gastrointestinal tumors.

CircRIMKLB promotes myoblast proliferation and inhibits differentiation by sponging miR-29c to release KCNJ12

ABSTRACT Muscle development is a complex process that was regulated by many factors, among which non-coding RNAs (ncRNAs) play a vital role in regulating multiple life activities of muscle cells. Circular RNA (circRNA), a type of non-coding RNA with closed-loop structure, has been reported to affect multiple life processes. However, the roles of circRNAs on muscle development have not been fully elucidated. The present study aimed to determine whether and how circRIMKLB affects muscle development. Our study revealed that circRIMKLB promoted myoblast proliferation and inhibited differentiation. Besides, miR-29c was proved as a downstream target of circRIMKLB using dual-luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) assay. Also, potassium inwardly rectifying channel subfamily J member 12 (KCNJ12) was identified as a novel target of miR-29c via dual-luciferase reporter assay, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), and western blot. CircRIMKLB and KCNJ12 were both proved to regulate cell cycle on muscle regeneration after injury in vivo. In conclusion, we demonstrated that circRIMKLB sponged miR-29c, releasing KCNJ12 to regulate myoblast proliferation and differentiation and regulating cell cycle during muscle regeneration after injury in vivo.

Closed-loop Nash equilibrium for a partial differential game with application to competitive personalized advertising

This paper is devoted to an N-person partial differential game whose dynamics of the state variable is described by a hyperbolic differential equation with certain boundary and initial conditions while the objective of each player is given by a finite horizon accumulated payoff functional with discounting. We extend the concept of a closed-loop Nash equilibrium for a partial differential game with the dynamics of the states described by a hyperbolic differential equation (a transport equation). We propose the definition of a dual closed-loop Nash equilibrium for which we give sufficient conditions. Moreover, we present the relationship between the Nash equilibria with the dual closed-loop and the classical closed-loop information structure. We apply the new results to the goodwill dynamics model in which the goodwill is influenced by personalized advertising and consumers’ recommendations for which we construct a dual closed-loop Nash equilibrium and we examine its economic properties.

Positioning control of liquid crystal elastomer actuator based on double closed-loop system structure

This paper proposes a control strategy with a double closed-loop system structure to achieve the positioning control of the photo-responsive liquid crystal elastomer (LCE) actuator. This work helps developing photo-responsive soft robot applications that are totally different from conventional electro-driven ones. In the proposed strategy, the outer loop is a combination of a PID controller in parallel with a feed-forward controller, the PID controller ensures that the positioning control target can be reached, and the feed-forward controller is an inverse model of the temperature-deformation relationship of the LCE actuator developed recently, to calculate the target temperature of the LCE actuator. The inner loop is a PID controller, which ensures that the temperature of the LCE actuator converges to the target value calculated by the feed-forward controller. Parameters of the inner PID controller are tuned using a simulation-experiment combined method based on the Hammerstein–Wiener model, and parameters of the outer PID controller are tuned based on experiments. Experiments are performed to show the effectiveness of the proposed method, and comparisons are made with conventional single closed-loop control structure. Such a double closed-loop structure has faster response and higher accuracy, and it lays a basis for possible photo-responsive soft robot applications.

Identification of circRNA Biomarker for Gastric Cancer through Integrated Analysis.

Gastric cancer (GC) is one of the most common malignant tumors and ranks third in cancer mortality globally. Although, a lot of advancements have been made in diagnosis and treatment of gastric cancer, there is still lack of ideal biomarker for the diagnosis and treatment of gastric cancer. Due to the poor prognosis, the survival rate is not improved much. Circular RNAs (circRNAs) are single-stranded RNAs with a covalently closed loop structure that don’t have the 5′-3′ polarity and a 3′ polyA tail. Because of their circular structure, circRNAs are more stable than linear RNAs. Previous studies have found that circRNAs are involved in several biological processes like cell cycle, proliferation, apoptosis, autophagy, migration and invasion in different cancers, and participate in some molecular mechanisms including sponging microRNAs (miRNAs), protein translation and binding to RNA-binding proteins. Several studies have reported that circRNAs play crucial role in the occurrence and development of different types of cancers. Although, some studies have reported several circRNAs in gastric cancer, more studies are needed in searching new biomarkers for gastric cancer diagnosis and treatment. Here, we investigated potential circRNA biomarkers for GC using next-generation sequencing (NGS) data collected from 5 paired GC samples. A total of 45,783 circRNAs were identified in all samples and among them 478 were differentially expressed (DE). The gene ontology (GO) analysis of the host genes of the DE circRNAs showed that some genes were enriched in several important biological processes, molecular functions and cellular components. The Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis revealed that some host genes were enriched in several GC related pathways. The circRNA-miRNA-gene interaction network analysis showed that two circRNAs circCEACAM5 and circCOL1A1 were interacted with gastric cancer related miRNAs, and their host genes were also the important therapeutic and prognostic biomarkers for GC. The experimental results also validated that these two circRNAs were DE in GC compared to adjacent normal tissues. Overall, our findings suggest that these two circRNAs circCEACAM5 and circCOL1A1 might be the potential biomarkers for the diagnosis and treatment of GC.

Eruption of the EUV Hot Channel from the Solar Limb and Associated Moving Type IV Radio Burst

Abstract Using the observations from the Solar Dynamics Observatory, we study an eruption of a hot-channel flux rope (FR) near the solar limb on 2015 February 9. The pre-eruptive structure is visible mainly in EUV 131 Å images, with two highly sheared loop structures. They undergo a slow rising motion and then reconnect to form an eruptive hot channel, as in the tether-cutting reconnection model. The J-shaped flare ribbons trace the footpoint of the FR that is identified as the hot channel. Initially, the hot channel is observed to rise slowly at 40 km s−1, followed by an exponential rise from 22:55 UT at a coronal height of 87 ± 2 Mm. Following the onset of the eruption at 23:00 UT, the flare reconnection then adds to the acceleration process of the coronal mass ejection (CME) within 3 R ⊙. Later on, the CME continues to accelerate at 8 m s−2 during its propagation period. Further, the eruption also launched type II radio bursts, which were followed by type III and type IVm radio bursts. The start and end times of the type IVm burst correspond to the CME’s core height of 1.5 and 6.1 R ⊙, respectively. Also, the spectral index is negative, suggesting that nonthermal electrons are trapped in the closed loop structure. Accompanied by this type IVm burst, this event is unique in the sense that the flare ribbons are very clearly observed together with the erupting hot channel, which strongly suggests that the hooked parts of the J-shaped flare ribbons outline the boundary of the erupting FR.

Model Predictive Control With a Cascaded Hammerstein Neural Network of a Wind Turbine Providing Frequency Containment Reserve

This article presents an application of neural network-based Model Predictive Control (MPC) to improve the wind turbine control system’s performance in providing frequency control ancillary services to the grid. A closed-loop Hammerstein structure is used to approximate the behavior of a 5MW floating offshore wind turbine with a Permanent Magnet Synchronous Generator (PMSG). The multilayer perceptron neural networks estimate the aerodynamic behavior of the nonlinear steady-state part, and the linear AutoRegressive with Exogenous input (ARX) is applied to identify the linear time-invariant dynamic part. Using the specific structure of the Cascade Hammerstein design simplifies the online linearization at each operating point. The proposed algorithm evades the necessity of nonlinear optimization and uses quadratic programming to obtain control actions. Eventually, the proposed control design provides a fast and stable response to the grid frequency variations with optimal pitch and torque cooperation. The performance of the MPC is compared with the gain-scheduled proportional-integral (PI) controller. Results demonstrate the effectiveness of the designed control system in providing Frequency Containment Reserve (FCR) and frequency regulation in the future of power systems.

Role of circular RNAs in immune-related diseases

Objective Circular RNAs (circRNAs) are non-coding RNAs (ncRNA) circularized without a 3' polyadenylation [poly-(A)] tail or a 5' cap, resulting in a covalently closed loop structure. circRNAs were first discovered in RNA viruses in the 1970s, but only a small number of circRNAs were discovered at that time due to limitations in traditional polyadenylated transcriptome analyses. With the development of specific biochemical and computational methods, recent studies have shown the presence of abundant circRNAs in eukaryotic transcriptomes. circRNAs play vital roles in many physiological and pathological processes, such as acting as miRNA sponges, binding to RNA-binding proteins (RBPs), acting as transcriptional regulatory factors, and even serving as translation templates. Current evidence has shown that circRNAs can be potentially used as excellent biomarkers for diagnosis, therapeutic effect evaluation, and prognostic assessment of a variety of diseases, and they may also provide effective therapeutic targets due to their stability and tissue and development-stage specificity. This review focuses on the properties of circRNAs and their immune relationship to disease, and explores the role of circRNAs in immune-related diseases and the directions of future research.

A 24 GHz Circularly Polarized On-chip Antenna for Short-Range Communication Application

This article presents a design method of miniaturized, circularly polarized (CP), concentric ring-shaped monopole on-chip antenna for 24 GHz short-range application. The proposed antenna covers automotive radar spectrum 22-29 GHz with a resonance at 24 GHz. Taking a simple circular ring-shaped patch as reference antenna, a small gap is introduced in the closed-loop structure that helps to provide the required travelling wave current distribution for realizing the CP property. Then a smaller circular ring is incorporated inside the reference antenna to improve the antenna performance in terms of CP characteristics. Finally, the proposed antenna is tuned to obtain the CP characteristics in the desired band ranging from 23.2 GHz to 27 GHz with 3-dB axial ratio (AR) bandwidth of 3.8 GHz. It offers a maximum gain of -4.5 dBi and wide angular range coverage (HPBW>75° in both E and H-plane). The standard CMOS process with only one level of mask (metal patterning) is used to realize the designed antenna. Compact in size of 3.8 mm × 4 mm × 0.678 mm, simple design layout, and its performance make the antenna as a suitable candidate for system-on-chip (SoC) application.

Robust Feedback Control for Discrete-Time Systems Based on Iterative LMIs with Polytopic Uncertainty Representations Subject to Stochastic Noise

This paper deals with the design of linear observer-based state feedback controllers with constant gains for a class of nonlinear discrete-time systems in the form of a quasi-linear representation in presence of stochastic noise. For taking into account nonlinearities in the design of linear observer-based state feedback controllers, a polytopic modeling approach is investigated. An optimization problem is formulated to reduce the sensitivity of the controlled system towards stochastic input, state, and output noise with a predefined covariance. Due to the nonlinearities, the separation principle does not hold, thus, the controller and the observer have to be designed simultaneously. For this purpose, a Lyapunov-based method is used, which provides, in addition to the controller and observer gains, a stability proof for the nonlinear closed loop in a predefined polytopic domain. In general, this leads to nonlinear matrix inequalities. To solve these nonlinear matrix inequalities efficiently, we propose an approach based on linear matrix inequalities (LMIs) with a superposed iteration rule. When using this iterative LMI approach, a minimization task can be solved additionally, which desensitizes the closed loop to stochastic noise. The proposed method additionally enables the consideration of different linear closed loop structures by a unified Lyapunov-based framework. The efficiency of the proposed approach is demonstrated and compared with a classical LQG approach for a nonlinear overhead traveling crane.

Dynamics of Eukaryotic mRNA Structure during Translation

Currently, there is no single concept of the optimal spatial structure of mRNA during translation. It is known that many proteins, associated with the 5' end of mRNA, interact with proteins associated with the 3' end. Moreover, this interaction often affects the activity of these proteins. It is possible within the same mRNA molecule only when the mRNA forms a circular structure in which its ends are spatially close. Discovery of such proteins, in the 90s of the 20th century, made it possible to formulate the closed-loop mRNA structure hypothesis, in which it is assumed that the ends of translationally active mRNA are fixed next to each other due to the interaction of proteins and (or) RNA. However, later it was shown that a closed-loop structure is not always necessary for translation. Moreover, some authors have proposed a model according to which the translating mRNA, on the contrary, should be unfolded into a linear structure. Thus, the spatial structure of the translating mRNA does not have to be universal for all mRNA and can change dynamically, which affects its functional activity. In this review, we have summarized a variety of experimental data and concepts on the relationship between the spatial structure of mRNA and its translational activity.

Siamese reciprocal classification and residual regression for robust object tracking

Recently, Siamese trackers have received more attention in visual tracking due to their satisfactory balance between performance and efficiency. However, most Siamese trackers neglect the misalignment between classification confidence and regression accuracy, which limits their best performance. In this paper, we proposed a novel reciprocal localization-aware classification and residual regression architecture with Siamese network named SiamRCRR. The proposed SiamRCRR consists of three subnetworks: a residual regression subnetwork to fully exploit the accuracy of object localization through the refinement of the bounding box, a localization-aware classification subnetwork to predict comprehensive scores of classification confidence and regression accuracy, and a Siamese subnetwork to extract features for classification and regression. The interaction of the residual regression subnetwork and localization-aware classification subnetwork forms a closed-loop structure to take advantage of the mutual benefit between classification and regression tasks. Therefore, the consistency between classification confidence and regression accuracy is guaranteed during tracking. Experiments on five challenging benchmarks including GOT-10k, OTB-100, LaSOT, VOT2019, and NFS show that SiamRCRR significantly outperforms its well-behaved counterparts in tracking accuracy and execution effectiveness.

Differential diagnosis of superficial duodenal epithelial tumor and non-neoplastic lesion in duodenum by magnified endoscopic examination with image-enhanced endoscopy.

Differential diagnosis of superficial duodenal epithelial tumors (SDETs) and non-neoplastic lesions (NNLs) in duodenum by endoscopy is difficult. Here, we attempted to distinguish them by magnified endoscopic examination with image-enhanced endoscopy (IEE-ME). Various IEE-ME findings of 95 SDETs who underwent endoscopic resection and 58 NNLs who underwent biopsy were retrospectively reviewed. When we compared the IEE-ME findings of SDETs and NNLs, the presence of demarcation line (DL) (97.9% vs. 79.3%, P = 0.0002), white opaque substance (WOS) (84.2% vs. 1.7%, P < 0.0001) and light blue crest (LBC) (93.7% vs. 32.8%, P < 0.0001) and the absence of enlarged marginal epithelium (EME) (98.9% vs. 62.1%, P < 0.0001) were significantly more frequent in SDETs than NNLs. When divided into each superficial structure, it was the most effective to evaluate the combination of WOS and LBC as SDET with open-loop structure (OLS), and the combination of DL and EME as SDET with closed-loop structure (CLS). However, LBC was excluded because of low inter- and intra-observer agreements. Finally, the sensitivity, specificity and accuracy for the diagnosis of SDETs were 88.4%, 98.3% and 92.2%, respectively, and we developed an algorithm for the differential diagnosis of duodenal lesions. We could distinguish SDET from NNL, diagnosed SDET as presence of WOS indicated OLS of superficial structure, and presence of DL and absence of EME indicated CLS of superficial structure.

Rno_circ_0001004 Acts as a miR-709 Molecular Sponge to Regulate the Growth Hormone Synthesis and Cell Proliferation.

(1) Background: As a novel type of non-coding RNA with a stable closed-loop structure, circular RNA (circRNA) can interact with microRNA (miRNA) and influence the expression of miRNA target genes. However, circRNA involved in pituitary growth hormone (GH) regulation is poorly understood. Our previous study revealed protein kinase C alpha (PRKCA) as the target gene of miR-709. Currently, the expression and function of rno_circRNA_0001004 in the rat pituitary gland is not clarified; (2) Methods: In this study, both bioinformatics analysis and dual-luciferase report assays showed a target relationship between rno_circRNA_0001004 and miR-709. Furthermore, the rno_circRNA_0001004 overexpression vector and si-circ_0001004 were constructed and transfected into GH3 cells; (3) Results: We found that rno_circRNA_0001004 expression was positively correlated with the PRKCA gene and GH expression levels, while it was negatively correlated with miR-709. In addition, overexpression of rno-circ_0001004 also promoted proliferation and relieved the inhibition of miR-709 in GH3 cells; (4) Conclusions: Our findings show that rno_circ_0001004 acts as a novel sponge for miR-709 to regulate GH synthesis and cell proliferation, and are the first case of discovery of the regulatory role of circRNA_0001004 in pituitary GH.

Circular RNA-EPHB4 As A Potential Biotarget In Colorectal Cancer: A Preliminary Analysis

Colorectal cancer (CRC) is among the top causes of cancer-related deaths. With the advent of new biomedical technologies, new therapeutic targets are being actively discovered. Circular RNAs (circRNAs) are characterized by the absence of covalently closed-loop structures at the 3′ and 5′ ends. Recent studies have shown that circRNAs are abnormally expressed in tumor tissues. Certain circRNAs have been reported to have potential as cancer biomarkers. Among all the circRNAs previously discovered, circ-EPHB4 seemed promising. Therefore, this study is aimed to determine the function of circEPHB4 in CRC. By utilizing in-silico prediction tools, qPCR and cell-based assays, we were able to provide preliminary insights into the role of circEPHB4. The expression of both circEPHB4 and linear EPHB4 were upregulated in our Malaysian CRC tissues and commercial cell lines as compared to the non-cancerous counterparts. Reduction of both circEPHB4 and EPHB4 had effects on wound healing, drug response and clonogenic abilities of SW-480 and HCT-116 cells. Our initial findings suggest that circ-EPHB4 may be involved in the regulation of CRC though further in-depth studies are needed.

Emerging Role and Mechanism of circRNAs in Pediatric Malignant Solid Tumors.

Circular RNAs (circRNAs) are non-coding RNAs with covalent closed-loop structures and are widely distributed in eukaryotes, conserved and stable as well as tissue-specific. Malignant solid tumors pose a serious health risk to children and are one of the leading causes of pediatric mortality. Studies have shown that circRNAs play an important regulatory role in the development of childhood malignant solid tumors, hence are potential biomarkers and therapeutic targets for tumors. This paper reviews the biological characteristics and functions of circRNAs as well as the research progress related to childhood malignant solid tumors.

Mutual-Feed Learning for Super-Resolution and Object Detection in Degraded Aerial Imagery

The resolution degradation poses a huge challenge for object detection (OD) in the aerial imagery. Existing methods utilize super resolution (SR) based on Generative Adversarial Network (GAN) to restore texture details in degraded images. However, constrained detection results are still acquired due to the object feature difference between restored and clear images. Therefore, we propose a simple-yet-effective learning method called Mutual-Feed Learning (MFL) to solve the problem in this paper. A closed-loop structure is designed via building the feedback connection based on the feedforward connection between the two tasks. It effectively delivers the object spatial and feature information from OD to SR, and provides restoration-enhanced images from SR to OD. Specifically, a Feedback of Region of Interest (FROI) module is introduced to realize a region-level discrimination under the guidance of object information. It guides the discrimination process of super resolution. Furthermore, a Multi-Scale Object Information (MSOI) module is developed to implement a feature-level restoration by narrowing differences in object-related features. It improves the generation process of super resolution. Then object detection can be performed in restoration-enhanced images to obtain more accurate results. Extensive experiments over NWPU VHR-10, COWC, and FAIR1M dataset show that the method can achieve state-of-the-art results.

Advances in Circular RNA and Its Applications.

Circular RNA (circRNA) is a novel endogenous non-coding RNA (ncRNA) that, like microRNA (miRNA), is a rapidly emerging RNA research topic. CircRNA, unlike traditional linear RNAs (which have 5' and 3' ends), has a closed-loop structure that is unaffected by RNA exonucleases. Thus, circRNA has sustained expression and is less sensitive to degradation. Since circRNAs have many miRNAs binding sites, eliminating their repressive effects on their target genes can strongly enhance their expression. CircRNAs serve an important regulatory role in disease onset and progression via specific circRNA-miRNA interactions. We summarized the current progress in elucidating mechanisms and biogenesis of circRNAs in this review. In particular, circRNAs can function mainly as miRNA sponges, regulating host gene expression and protein transportation. Finally, we discussed the application prospects and significant challenges for the development of circRNA-based therapeutics.

Data-driven trajectory tracking control for autonomous underwater vehicle based on iterative extended state observer.

In this study, we explore the precise trajectory tracking control problem of autonomous underwater vehicle (AUV) under the disturbance of the underwater environment. First, a model-free adaptive control (MFAC) is designed based on data-driven ideology and a full-form dynamic linearization (FFDL) method is utilized to online estimate time-varying parameter pseudo gradient (PG) to establish an equivalent data model of AUV motion. Second, the iterative extended state observer (IESO) scheme is designed to combine with FFDL-MFAC. Because the proposed novel controller is able to learn from repeated iterations, the proposed novel controller can estimate and compensate the model approximation error produced by external environmental unknown disturbance. Third, three-dimensional motion is decoupled into horizontal and vertical and a multi closed-loop control structure is designed that exhibits faster convergence rate and reduces sensitivity to parameter jumps than single closed-loop system. Finally, two simulation scenarios are designed featuring non external disturbance and Gaussian noise of signal-to-noise ratio of 90 dB. The simulation results reveal the superiority of FFDL. Furthermore, we adpot the technical parameters data of T-SEA I AUV to conduct numerical simulation, aunderwater trajectory as the tracking scenario and set waves to 0.5 m and current to 0.2 m/s to simulate Lv.2 ocean conditions of "International Ocean State Standard". The simulation results demonstrate the effectiveness and robustness of the proposed tracking control algorithm.

Design and Analysis of Double Integrating and Dead time Processes

Presence of integrator and time delay in transfer functions of physical processes makes the system difficult to control by conventional methods. This paper proposes a novel design of a modified closed loop structure for double integrating plus dead time (DIPDT) processes based on the locus of perturbed relay system (LPRS). A control law has been proposed using LPRS technique which includes the transition or feedthrough matrix (D) for integrating process. The LPRS method provides good servo behaviour but it results in offset in presence of disturbance. Hence a novel modified control structure with a lead lag compensator is designed and the closed-loop performance is compared with that of existing example of the literature works of DIPDT for servo and regulatory responses. Comparison of performance error indices and percent overshoot (PO%) with that of the other existing works reveals the superiority of the proposed scheme.