Exact controllability of rational expectations model with multiplicative noise and input delay

This paper considers the rational expectations model with multiplicative noise and input delay,where the system dynamics rely on the conditional expectations of future states.The main contribution is to obtain a sufficient condition for the exact controllability of the rational expectations model.In particular,we derive a sufficient Gramian matrix condition and a rank condition for the delay-free case.The key is the solvability of the backward stochastic difference equations with input delay which is derived from the forward and backward stochastic system.

Consensus Seeking for Discrete-time Multi-agent Systems with Communication Delay

This paper studies the consensus problem for discrete-time multi-agent systems of first-order in the presence of constant communication delay. Provided that the agent dynamics is unstable and the network topology is undirected, effects of two kinds of communication delays on consensus are investigated. When the relative information is affected by delay, we show that the effect of delay can be alleviated by using the historical input information in the protocol design. On the other hand, if the communication delay only influences the actually transmitted information, sufficient condition admitting any large yet bounded delay for consensus is obtained, and the delay in this case is allowed to be unknown and time-varying. Finally, simulation results are provided to demonstrate the effectiveness of the theoretical results. © 2014 Chinese Association of Automation.

Advances in research of land surface evapotranspiration at home and abroad

Land surface evapotranspiration (ET) is an important part of the hydrologic cycle and energy balances.With the development of remote sensing technology,research on monitoring and estimating of evapotranspiration has made important progress.This paper summarizes advances in measuring and estimating regional evapotranspiration at home and abroad based on traditional methods and remote sensing.This summary includes such methods as Bowen,Gradient,Penman-Monteith,Water Balance,Eddy Correlation,SPAC,Energy Balance and Remote Sensing.Also,the evapotranspiration achievements in the Heihe River Basin are also discussed.Finally,the existing problems in regional evapotranspiration research and future development prospects are also discussed at the conclusion of this paper.

Clinical Characteristics and Outcomes of Severe or Critical COVID-19 Patients Presenting No Respiratory Symptoms or Fever at Onset

It is difficult to identify suspected cases of atypical patients with coronavirus disease 2019(COVID-19),and data on severe or critical patients are scanty.This retrospective study presents the clinical,laboratory,and radiological profiles,treatments,and outcomes of atypical COVID-19 patients without respiratory symptoms or fever at onset.The study examined ten atypical patients out of 909 severe or critical patients diagnosed with COVID-19 in Wuhan Union Hospital West Campus between 25 January 2020 and 10 February 2020.Data were obtained from the electronic medical records of severe or critical patients without respiratory symptoms or fever at onset.Outcomes were followed up to discharge or death.Among 943 COVID-19 patients,909(96.4%)were severe or critical type.Of the severe or critical patients,ten(1.1%)presented without respiratory symptoms or fever at admission.The median age of the ten participants was 63 years(interquartile range(IQR):57–72),and seven participants were men.The median time from symptom onset to admission was 14 d(IQR:7–20).Eight of the ten patients had chronic diseases.The patients had fatigue(n=5),headache or dizziness(n=4),diarrhea(n=5),anorexia(n=3),nausea or vomiting(n=3),and eye discomfort(n=1).Four patients were found to have lymphopenia.Imaging examination revealed that nine patients had bilateral pneumonia and one had unilateral pneumonia.Eventually,two patients died and eight were discharged.In the discharged patients,the median time from admission to discharge lasted 24 d(IQR:13–43).In summary,some severe or critical COVID-19 patients were found to have no respiratory symptoms or fever at onset.All such atypical cases should be identified and quarantined as early as possible,since they tend to have a prolonged hospital stay or fatal outcomes.Chest computed tomography(CT)scan and nucleic acid detection should be performed immediately on close contacts of COVID-19 patients to screen out those with atypical infections,even if the contacts present without respiratory symptoms or fever at onset.

Omics methods predict the prognosis and treatment efficacy of chronic obstructive pulmonary disease

To the Editor:Chronic obstructive pulmonary disease(COPD)is a condition that severely endangers human health.In 2018,Wang et al^([1])reported that there are approximately 100 million patients with COPD in China,with a 13.7%prevalence in people aged over 40 years.The disease severity,frequency of exacerbations,and comorbidities,which are commonly(30–57%)observed in patients with COPD,are the three most crucial elements affecting the economic and societal consequences of COPD.^([2])Hospitalizations for exacerbations are the main contributors to health care expenses.To reduce the clinical and financial burden of COPD,interventions are needed to slow the disease course,avoid exacerbations,and reduce comorbidities,such as approaches for improving the prognosis and treatment efficacy in COPD.

A Stackelberg strategy for continuous-time mixed H2/H∞ control problem with time delay

This paper is concerned with the mixed H2/H∞ control with linear continuous time system and time delay. To deal with this, we presents a Stackelberg strategy by treating the control input and the disturbance as leader and follower, respectively. The leader＇s control strategy minimizes the cost function which is in H2 norm and the follower＇s control strategy maximizes the cost function which is in H∞ norm. The main technique of this paper is deal with the noncausal relationship of the variables caused by time delay in the control input by introducing two costates to capture the future information and one state to capture the past information. Through theory analyzing, the Stackelberg strategy exists uniquely. Moreover, with the assistance of the extended state space expression, the explicit expression of the strategy is obtained.

Atrial of arbidol hydrochloride in adults with COVID-19

Background: To date, there is no effective medicine to treat coronavirus disease 2019 (COVID-19), and the antiviral efficacy of arbidol in the treatment for COVID-19 remained equivocal and controversial. The purpose of this study was to evaluate the efficacy and safety of arbidol tablets in the treatment of COVID-19.Methods: This was a prospective, open-label, controlled and multicenter investigator-initiated trial involving adult patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Patients were stratified 1:2 to either standard-of-care (SOC) or SOC plus arbidol tablets (oral administration of 200 mg per time, three times a day for 14 days). The primary endpoint was negative conversion of SARS-CoV-2 within the first week. The rates and 95% confidential intervals were calculated for each variable.Results: A total of 99 patients with laboratory-confirmed SARS-CoV-2 infection were enrolled;66 were assigned to the SOC plus arbidol tablets group, and 33 to the SOC group. The negative conversion rate of SARS-CoV-2 within the first week in patients receiving arbidol tablets was significantly higher than that of the SOC group (70.3% [45/64]vs. 42.4% [14/33];difference of conversion rate 27.9%;95% confidence interval [CI], 7.7%-48.1%;P=0.008). Compared to those in the SOC group, patients receiving arbidol tablets had a shorter duration of clinical recovery (median 7.0 daysvs. 12.0 days;hazard ratio [HR]: 1.877, 95% CI: 1.151-3.060,P=0.006), symptom of fever (median 3.0 daysvs. 12.0 days;HR: 18.990, 95% CI: 5.350-67.410,P<0.001), as well as hospitalization (median 12.5 daysvs. 20.0 days;P<0.001). Moreover, the addition of arbidol tablets to SOC led to more rapid normalization of declined blood lymphocytes (median 10.0 daysvs. 14.5 days;P > 0.05). The most common adverse event in the arbidol tablets group was the elevation of transaminase (5/200, 2.5%), and no one withdrew from the study due to adverse events or disease progression.Conclusions: SOC plus arbidol tablets significantly increase the negative conversion rate of SARS-CoV-2 within the first week and accelerate the recovery of COVID-19 patients. During the treatment with arbidol tablets, we find no significant serious adverse events.

Explicit solution to forward and backward stochastic differential equations with state delay and its application to optimal control

This paper is concerned with linear forward–backward stochastic differential equations(FBSDEs)with state delay,the solvability which is much more complex than the case of no delay or input delay caused by the prediction of the backward processes of the future time.To overcome this difficulty,we innovatively establish the non-homogeneous relationship between the backward and forward processes with the help of the corresponding discrete-time system.The main contribution is to give the explicit solution to the FBSDEs with state delay in terms of partial Riccati equations for the first time.The presented results form the basis to solve the challenging problem of linear quadratic optimal control for multiplicative-noise stochastic systems with state delay.