A data-driven epidemic model with human mobility and vaccination protection for COVID-19 prediction.

Epidemiological models allow for quantifying the dynamic characteristics of large-scale outbreaks. However, capturing detailed and accurate epidemiological information often requires consideration of multiple kinetic mechanisms and parameters. Due to the uncertainty of pandemic evolution, such as pathogen variation, host immune response and changes in mitigation strategies, the parameter evaluation and state prediction of complex epidemiological models are challenging. Here, we develop a data-driven epidemic model with a generalized SEIR mechanistic structure that includes new compartments, human mobility and vaccination protection. To address the issue of model complexity, we embed the epidemiological model dynamics into physics-informed neural networks (PINN), taking the observed series of time instances as direct input of the network to simultaneously infer unknown parameters and unobserved dynamics of the underlying model. Using actual data during the COVID-19 outbreak in Australia, Israel, and Switzerland, our model framework demonstrates satisfactory performance in multi-step ahead predictions compared to several benchmark models. Moreover, our model infers time-varying parameters such as transmission rates, hospitalization ratios, and effective reproduction numbers, as well as calculates the latent period and asymptomatic infection count, which are typically unreported in public data. Finally, we employ the proposed data-driven model to analyze the impact of different mitigation strategies on COVID-19.

Reactive-diffusion epidemic model on human mobility networks: Analysis and applications to COVID-19 in China.

The complex dynamics of human mobility, combined with sporadic cases of local outbreaks, make assessing the impact of large-scale social distancing on COVID-19 propagation in China a challenge. In this paper, with the travel big dataset supported by Baidu migration platform, we develop a reactive-diffusion epidemic model on human mobility networks to characterize the spatio-temporal propagation of COVID-19, and a novel time-dependent function is incorporated into the model to describe the effects of human intervention. By applying the system control theory, we discuss both constant and time-varying threshold behavior of proposed model. In the context of population mobility-mediated epidemics in China, we explore the transmission patterns of COVID-19 in city clusters. The results suggest that human intervention significantly inhibits the high correlation between population mobility and infection cases. Furthermore, by simulating different population flow scenarios, we reveal spatial diffusion phenomenon of cases from cities with high infection density to cities with low infection density. Finally, our model exhibits acceptable prediction performance using actual case data. The localized analytical results verify the ability of the PDE model to correctly describe the epidemic propagation and provide new insights for controlling the spread of COVID-19.

Novel epidemic models on PSO-based networks.

This paper proposes two spatio-temporal epidemic network models based on popularity and similarity optimization (PSO), called r-SI and r-SIS, respectively, in which new connections take both popularity and similarity into account. In the spatial dimension, the epidemic process is described by the diffusion equation; in the time dimension, the growth of an epidemic is described by the logistic map. Both models are represented by partial differential equations, and can be easily solved. Simulations are performed on both artificial and real networks, demonstrating the effectiveness of the two models.

An iterative Q-learning based global consensus of discrete-time saturated multi-agent systems.

This paper addresses the consensus problem of discrete-time multiagent systems (DTMASs), which are subject to input saturation and lack of the information of agent dynamics. In the previous works, the DTMASs with input saturation can achieve semiglobal consensus by utilizing the low gain feedback (LGF) method, but computing the LGF matrices by solving the modified algebraic Riccati equation requires the knowledge of agent dynamics. In this paper, motivated by the reinforcement learning method, we propose a model-free Q-learning algorithm to obtain the LGF matrices for the DTMASs achieving global consensus. Firstly, we define a Q-learning function and deduce a Q-learning Bellman equation, whose solution can work out the LGF matrix. Then, we develop an iterative Q-learning algorithm to obtain the LGF matrix without the requirement of the knowledge about agent dynamics. Moreover, the DTMASs can achieve global consensus. Lastly, some simulation results are proposed to validate the effectiveness of the Q-learning algorithm and show the effect on the rate of convergence from the initial states of agents and the input saturation limit.

A New Model for Complex Dynamical Networks Considering Random Data Loss.

Model construction is a very fundamental and important issue in the field of complex dynamical networks. With the state-coupling complex dynamical network model proposed, many kinds of complex dynamical network models were introduced by considering various practical situations. In this paper, aiming at the data loss which may take place in the communication between any pair of directly connected nodes in a complex dynamical network, we propose a new discrete-time complex dynamical network model by constructing an auxiliary observer and choosing the observer states to compensate for the lost states in the coupling term. By employing Lyapunov stability theory and stochastic analysis, a sufficient condition is derived to guarantee the compensation values finally equal to the lost values, namely, the influence of data loss is finally eliminated in the proposed model. Moreover, we generalize the modeling method to output-coupling complex dynamical networks. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed model.

State Estimation for General Complex Dynamical Networks with Incompletely Measured Information.

Estimating uncertain state variables of a general complex dynamical network with randomly incomplete measurements of transmitted output variables is investigated in this paper. The incomplete measurements, occurring randomly through the transmission of output variables, always cause the failure of the state estimation process. Different from the existing methods, we propose a novel method to handle the incomplete measurements, which can perform well to balance the excessively deviated estimators under the influence of incomplete measurements. In particular, the proposed method has no special limitation on the node dynamics compared with many existing methods. By employing the Lyapunov stability theory along with the stochastic analysis method, sufficient criteria are deduced rigorously to ensure obtaining the proper estimator gains with known model parameters. Illustrative simulation for the complex dynamical network composed of chaotic nodes are given to show the validity and efficiency of the proposed method.

Noninvasive perioperative evaluation of right ventricular function in children with tetralogy of Fallot.

Early and accurate noninvasive means of identifying right ventricular (RV) dysfunction in children with tetralogy of Fallot (TOF) are needed. RV function was examined using tissue Doppler imaging (TDI), strain rate (SR), and strain analysis (SA) in children before (N = 37) and after (6-12 months; N = 32) TOF repair, and in a control group of children (N = 37). Plasma concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP) and matrix metalloproteinase 9 (MMP-9) were measured. TDI, SR, and SA revealed that RV systolic and diastolic function indices were lower preoperatively in the TOF group compared with the control group, and did not improve after TOF repair. Plasma NT-proBNP concentrations were significantly higher in the TOF group pre- and postoperatively compared with the control group. In the preoperative TOF group, NT-proBNP concentration was significantly correlated with peak systolic SR and systolic strain in the mid segments of RV free wall. Plasma MMP-9 concentrations were significantly increased in the preoperative TOF group compared with the control group, and significantly correlated with plasma NT-proBNP and logNT-proBNP concentrations. RV function correlated with plasma NT-proBNP concentrations in children with TOF. Assessment of this noninvasive measure may help identify RV dysfunction in patients with TOF before they become clinically symptomatic.

A new method for evaluating tricuspid valve displacement in children with Ebstein's anomaly: using the annulus and coronary sinus as a reference point.

This study aimed to investigate the reference point for the downward displacement of the posterior and anterior leaflets of the tricuspid valve using echocardiography in children with Ebstein's anomaly. This study enrolled 25 patients with Ebstein's anomaly. The extent of downward displacement of the posterior and anterior leaflets of the tricuspid valve was evaluated by echocardiography using the tricuspid annulus and the coronary sinus as reference points. These results were compared with the surgical findings. The findings showed displacement of the simple septal leaflet in 1 patient, displacement of both the septal and posterior leaflets in 22 patients, displacement of both the anterior and posterior leaflets in 1 patient, and displacement of all the leaflets in 1 patient. Because the septal and posterior leaflets were close to the apex or because the posterior leaflet was nearly absent, the displacement distance of the septal and posterior leaflets could not be measured accurately in two patients. The displacement distance of the septal and posterior leaflets in the remaining 22 patients were 2.08 ± 1.15 and 2.58 ± 1.06 cm, respectively. The displacement distances of the anterior leaflet in two patients were respectively 1.0 and 2.2 cm. These results were similar to those measured during surgery. The direction of the valvular regurgitation flow was anterolateral in the apical four-chamber and apical right heart two-chamber views in patients with the downward displacement of the anterior leaflet. The tricuspid valve annulus and the coronary sinus are ideal reference points for evaluating the downward displacement of the posterior and anterior leaflets of the tricuspid valve. It is critical to evaluate the downward displacement of the anterior leaflet that the direction of the tricuspid regurgitation flow is changed.

Epidemic spreading in metapopulation networks with heterogeneous infection rates.

In this paper, we study epidemic spreading in metapopulation networks wherein each node represents a subpopulation symbolizing a city or an urban area and links connecting nodes correspond to the human traveling routes among cities. Differently from previous studies, we introduce a heterogeneous infection rate to characterize the effect of nodes' local properties, such as population density, individual health habits, and social conditions, on epidemic infectivity. By means of a mean-field approach and Monte Carlo simulations, we explore how the heterogeneity of the infection rate affects the epidemic dynamics, and find that large fluctuations of the infection rate have a profound impact on the epidemic threshold as well as the temporal behavior of the prevalence above the epidemic threshold. This work can refine our understanding of epidemic spreading in metapopulation networks with the effect of nodes' local properties.

Time-varying human mobility patterns with metapopulation epidemic dynamics.

In this paper, explicitly considering the influences of an epidemic outbreak on human travel, a time-varying human mobility pattern is introduced to model the time variation of global human travel. The impacts of the pattern on epidemic dynamics in heterogeneous metapopulation networks, wherein each node represents a subpopulation with any number of individuals, are investigated by using a mean-field approach. The results show that the pattern does not alter the epidemic threshold, but can slightly lower the final average density of infected individuals as a whole. More importantly, we also find that the pattern produces different impacts on nodes with different degree, and that there exists a critical degree k c . For nodes with degree smaller than k c , the pattern produces a positive impact on epidemic mitigation; conversely, for nodes with degree larger than k c , the pattern produces a negative impact on epidemic mitigation.

Kinematic modelling and experimental testing of a particle-jamming soft robot based on a DEM-FEM coupling method.

Particle-jamming soft robots are characterised by high flexibility in motion and high stiffness when executing a task. Regarding particle jamming of soft robots, the discrete element method (DEM)-finite element method (FEM) coupling was used for modelling and control. At first, a real-time particle-jamming soft actuator was proposed by integrating advantages of the driving Pneu-Net and the driven particle-jamming mechanism. Then, DEM and FEM were separately employed to determine the force-chain structure of the particle-jamming mechanism and the bending deformation performance of the pneumatic actuator. Furthermore, the piecewise constant curvature method was adopted for forward and inverse kinematic modelling of the particle-jamming soft robot. Finally, a prototype of the coupled particle-jamming soft robot was prepared, and a visual tracking test platform was established. The adaptive control method was proposed to compensate for the accuracy of motion trajectories. The variable-stiffness performance of the soft robot was verified by conducting stiffness tests and bending tests. The results provide novel theoretical and technical support for the modelling and control of variable-stiffness soft robots.

[Expression level and clinical significance of CD44 and CD33 in 77 patients with benign lymphoadenosis of oral mucosa].

PURPOSE: To investigate the expression and clinical significance of CD44 and CD33 in benign lymphoadenosis of oral mucosa(BLOM). METHODS: From January 2017 to March 2020, seventy-seven BLOM wax blocks from the Department of Pathology of Qingdao Traditional Chinese Medicine Hospital were selected as the experimental group, and 63 cases of normal oral mucosal tissue wax blocks during the same period were selected as the control group. Immunohistochemical method was used to detect the positive expression of CD44 and CD33 in the two groups.Spearman correlation analysis was used to analyze the correlation between the positive expression of CD33 and the positive expression of CD44 in the diseased tissues of BLOM patients.The general information about patients were collected.The relationship between the expression of CD33 and CD44 in the diseased tissues of BLOM patients and the clinicopathological characteristics of BLOM patients were analyzed. SPSS 21.0 software package was used for statistical analysis of the data. RESULTS: The positive expression rates of CD33 in the control group and the experimental group were 95.24% and 63.64%, respectively, and the difference was statistically significant(P＜0.05). The positive expression rates of CD44 in the control group and the experimental group were 93.65% and 67.53%, respectively, and the difference was statistically significant(P＜0.05). The results of Spearman correlation analysis showed that the positive expression of CD33 in the diseased tissues of BLOM patients was positively correlated with the positive expression of CD44 (r=0.834, P=0.002). The expression of CD33 and CD44 in the diseased tissues of patients with BLOM were related to clinical type, degree of inflammation, presence or absence of lymphoid follicles, and lymphocyte infiltration(P＜0.05), but not related to age, gender, course of disease, location, and epithelial surface keratinization(P＞0.05). CONCLUSIONS: The positive expression rate of CD33 and CD44 in the BLOM tissues decreased, which was closely related to the clinical type, degree of inflammation, presence or absence of lymphoid follicles, and lymphocyte infiltration.

Phase I study of a non-S2P SARS-CoV-2 mRNA vaccine LVRNA009 in Chinese adults.

BACKGROUND: COVID-19 caused by SARS-CoV-2 is a great threat to public health. We present the safety and immunogenicity data from a phase I trial in China of an mRNA vaccine (LVRNA009). METHODS: In the single-centre, double-blind, placebo-controlled and dose-escalation study, 72 healthy unvaccinated adults aged 18-59 years were randomized (3:1) to receive LVRNA009 with one of three vaccine dosage (25, 50 and 100 µg) or placebo, to evaluate for the safety, tolerability and immunogenicity of LVRNA009. RESULTS: All these participants received two injections 28 days apart. No adverse events higher than grade 2 were reported during the study. A total of 30 participants (42 %) reported solicited adverse reactions during the first 14 days after vaccinations. Of the events reported, fever (n = 11, 15 %) was the most common systemic adverse reaction, and pain at the injection site (n = 17, 24 %) was the most frequent solicited local adverse reaction. Anti-S-protein IgG and neutralising antibodies were observed to have been induced 14 days after the first dose, significantly increased 7 days after the second dose, and remained at a high level 28 days after the second dose. Specific T-cell responses peaked 7 days and persisted 28 days after second vaccination. CONCLUSION: LVRNA009 has demonstrated promising results in safety and tolerability at all three dose levels among Chinese adults. LVRNA009 at three dose levels could rapidly induce strong humoral and cellular immune responses, including binding and neutralising antibody production and IFN- γ secretion, which showed good immunogenicity. CLINICAL TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT05364047; Chictr.org.cn ChiCTR2100049349.

[Characteristics of pulmonary valve annular motion identified by quantitative tissue velocity imaging in children with pulmonary hypertension].

OBJECTIVE: To investigate the characteristics of pulmonary valve annular motion by quantitative tissue velocity imaging (QTVI) in children with pulmonary hypertension. METHODS: The pulmonary valve annular motion was assessed by QTVI in 32 children with pulmonary hypertension and 32 healthy children. The QTVI sample volume was set at the point of pulmonary valve annulus to acquire speed-time curve and the parameters from the views of parasternal aortic short-axis or subxiphoid right ventricular outflow long-axis. The parameters of pulmonary valve annular motion of children with pulmonary hypertension were compared to those of normal children. RESULTS: The speed-time curve of pulmonary valve annulus was similar with that of tricuspid annulus in normal children. Compared to normal children, the ratio of Ea/Aa (the velocity parameter of pulmonary valve annular motion) was significantly lower in children with pulmonary hypertension (0.68 ±0.36 Compared with 1.18 ±0.43, P<0.001); and the value of QTVI-Tei index at the pulmonary annulus was significantly higher (0.82 ±0.34 Compared with 0.37 ±0.05, P<0.001). The QTVI-Tei index was positively correlated with the resistance of pulmonary vessel (r=0.556, P<0.001). CONCLUSION: The ratio of Ea/Aa is decreased, the value of QTVI-Tei index is increased and QTVI-Tei index is positively correlated with the resistance of pulmonary vessel in children with pulmonary hypertension.

[Effects of acupoint heat-sensitization moxibustion on the gastrin and motilin in chronic diarrhea patients of Pi-Shen deficiency syndrome].

OBJECTIVE: To observe the therapeutic efficacy of acupoint heat-sensitization moxibustion on chronic diarrhea patients as well as its effects on the levels of gastrointestinal neurotic mediators such as serum gastrin (GAS) and plasma motilin (MTL). METHODS: Sixty chronic diarrhea patients of Pi-Shen deficiency syndrome were randomly assigned to Group A (30 cases, treated with acupoint heat-sensitization moxibustion, once daily) and Group B (30 cases, treated with Changtai Oral Liquid, 10 mL each time, three times daily). The therapeutic course was 4 weeks. Another 20 healthy volunteers were recruited as the health control group. The levels of serum GAS and plasma MTL were detected using radioimmunoassay before and after treatment. The cured rate, the markedly effective case, the effective case, the ineffective case, and the total effective rate were calculated by the end of the treatment. RESULTS: Before treatment the serum GAS level was lower and the plasma MTL level higher in the two patient groups than in the health control group with statistical difference (P<0.05). There was no statistical difference in the symptom integral between the two patient groups and the health control group (P>0.05). After treatment the serum GAS level increased, the plasma MTL level and the symptom integral decreased in the two patient groups, showing statistical difference when compared with the same group before treatment (P<0.05, P<0.01). After treatment the symptom integral was lower in the treatment group than in the control group with statistical difference (P<0.05). There was no statistical difference in the GAS and MTL levels between the two patient groups (P>0.05). The total effective rate for clinical symptoms was significantly higher in Group A than in Group B with statistical difference (93.3% vs 73.3%, P<0.05). CONCLUSIONS: The therapy of acupoint heat-sensitization moxibustion was effective for chronic diarrhea patients of Pi-Shen deficiency syndrome. It could regulate the levels of serum GAS and plasma MTL and improve the patients' clinical symptoms.

[Echocardiographic diagnosis of partial anomalous pulmonary venous connection].

OBJECTIVE: To investigate partial anomalous pulmonary venous connection (PAPVC) with echocardiography. METHODS: The right ventricular volume overload was detected by routine echocardiography in 37 child patients, who underwent further echocardiography to find the abnormal locations of pulmonary vein opening at superior, inferior vena cava and right atrium. The ultrasound results were compared with surgical findings. RESULTS: In 30 patients the ultrasound diagnosis was consistent with surgery results, 7 were misdiagnosed by ultrasound with a detective rate of 81.1 %. All 37 PAPVC patients presented varying degrees of right heart enlargement; PAPVC combined with atrial septal defect (ASD) was found in 34 cases. CONCLUSION: The possibility of PAPVC should be considered when unexplained right heart volume overload was detected by echocardiography. Superior, inferior vena cava and right atrium should be inspected when the pulmonary veins were not seen in echocardiography.

Consensus-Based Distributed Reduced-Order Observer Design for LTI Systems.

In this article, we refocus on the distributed observer construction of a continuous-time linear time-invariant (LTI) system, which is called the target system, by using a network of observers to measure the output of the target system. Each observer can access only a part of the component information of the output of the target system, but the consensus-based communication among them can make it possible for each observer to estimate the full state vector of the target system asymptotically. The main objective of this article is to simplify the distributed reduced-order observer design for the LTI system on the basis of the consensus communication pattern. For observers interacting on a directed graph, we first address the problem of the distributed reduced-order observer design for the detectable target system and provide sufficient conditions involving the topology information to guarantee the existence of the distributed reduced-order observer. Then, the dependence on the topology information in the sufficient conditions will be eliminated by using the adaptive strategy and so that a completely distributed reduced-order observer can be designed for the target system. Finally, some numerical simulations are proposed to verify the theoretical results.

Consensus of Continuous-Time Linear Multiagent Systems With Discrete Measurements.

This article concerns the robust consensus problem of continuous-time linear multiagent systems (MASs) with uncertainty and discrete-time measurement information, where the output measurement information is in the data-sampled form. Distributed output-feedback protocol with or without controller interaction is proposed for each agent. Specifically, the output-feedback protocol runs in continuous time with an output error correction term mixed with the discrete-time measurement information. The concrete algorithm is given for the construction of the feedback matrices. Then, by using the delay-input approach, sufficient conditions are provided for the robust consensus of this kind of MASs interacting over networks described by the directed graphs. Finally, numerical simulations are given to illustrate the theoretical results.

Observer-Based Multiagent Bipartite Consensus With Deterministic Disturbances and Antagonistic Interactions.

This article studies the multiagent bipartite consensus in networks with deterministic disturbances and antagonistic interactions. An observer-based output-feedback controller design is provided to guarantee the bipartite consensus with deterministic disturbances that satisfy the matching condition. Then, by considering that the bandwidths of communication channels are limited in practical systems, the event-triggered scenario of the proposed output controller for the bipartite consensus is further studied; the node-based broadcast updating fashion is utilized and the Zeno behavior is ruled out. Simulations are also offered to support the theoretical results of protocol designs.

Sonographic measurement of thyroid volumes in healthy Chinese infants aged 0 to 12 months.

OBJECTIVES: The purposes of this study were to determine thyroid volumes in healthy Chinese infants aged 0 to 12 months and to provide reference data for normal thyroid growth. METHODS: A total of 408 healthy infants (229 male and 179 female) were enrolled in the study. The length, breadth, and depth of the thyroid gland were measured with sonography. The volume of each lobe was calculated by the correct ellipsoid formula (volume = length × breadth × depth × 0.479). RESULTS: All of the infants' thyroids showed a normal uniform echo texture on sonography. The thyroid volume increased with age (r = 0.519; P < .001). Moreover, positive associations were noted between thyroid volume and height and weight (r = 0.517; P < . 001; r = 0.499; P < .001, respectively). No significant differences based on sex were found (t = 1.784; P = .075). CONCLUSIONS: The thyroid volumes in these healthy Chinese infants varied from those reported in the published literature on healthy European infants. It is important to establish local reference ranges for thyroid volumes in healthy infants.