Non-intrusive methods for eye tracking are important for many applications of vision-based human computer interaction. However, due to the high nonlinearity of eye motion, how to ensure the robust- ness of external in...Non-intrusive methods for eye tracking are important for many applications of vision-based human computer interaction. However, due to the high nonlinearity of eye motion, how to ensure the robust- ness of external interference and accuracy of eye tracking poses the primary obstacle to the integration of eye movements into today＇s interfaces. In this paper, we present a strong tracking finite-difference extended Kalman filter algorithm, aiming to overcome the difficulty in modeling nonlinear eye tracking. In filtering calculation, strong tracking factor is introduced to modify a priori covariance matrix and improve the accuracy of the filter. The filter uses finite-difference method to calculate partial derivatives of nonlinear functions for eye tracking. The latest experimental results show the validity of our method for eye tracking under realistic conditions.展开更多
Objective The aim of this study was to explore the method and standard for rapidly screening low temperature-resistant pepper germplasm resources and provide a theoretical basis for the breeding of low temperature-res...Objective The aim of this study was to explore the method and standard for rapidly screening low temperature-resistant pepper germplasm resources and provide a theoretical basis for the breeding of low temperature-resistant pepper. [ Method ] With 110 pigment pepper seeds as the materials, their germination vigor under optimum temperature and suboptimal temperature were determined by means of roll rapid germination, and seeds with different genetic types were evaluated from aspects of germination vigor and its interval division. [ Result ] 37 pepper seeds with stronger low temperature resistance were screened. [ Conclusion]This study provides an important basis for screening low temperature-resistant pepper germplasm resources.展开更多
In this paper,an adaptive dynamic programming(ADP)strategy is investigated for discrete-time nonlinear systems with unknown nonlinear dynamics subject to input saturation.To save the communication resources between th...In this paper,an adaptive dynamic programming(ADP)strategy is investigated for discrete-time nonlinear systems with unknown nonlinear dynamics subject to input saturation.To save the communication resources between the controller and the actuators,stochastic communication protocols(SCPs)are adopted to schedule the control signal,and therefore the closed-loop system is essentially a protocol-induced switching system.A neural network(NN)-based identifier with a robust term is exploited for approximating the unknown nonlinear system,and a set of switch-based updating rules with an additional tunable parameter of NN weights are developed with the help of the gradient descent.By virtue of a novel Lyapunov function,a sufficient condition is proposed to achieve the stability of both system identification errors and the update dynamics of NN weights.Then,a value iterative ADP algorithm in an offline way is proposed to solve the optimal control of protocol-induced switching systems with saturation constraints,and the convergence is profoundly discussed in light of mathematical induction.Furthermore,an actor-critic NN scheme is developed to approximate the control law and the proposed performance index function in the framework of ADP,and the stability of the closed-loop system is analyzed in view of the Lyapunov theory.Finally,the numerical simulation results are presented to demonstrate the effectiveness of the proposed control scheme.展开更多
The urgent need to expand the donor pool in order to attend to the growing demand for liver transplantation has obliged physicians to consider the use of suboptimal liver grafts and also to redefine the preservation s...The urgent need to expand the donor pool in order to attend to the growing demand for liver transplantation has obliged physicians to consider the use of suboptimal liver grafts and also to redefine the preservation strategies. This review examines the different methods of liver graft preservation, focusing on the latest advances in both static cold storage and machine perfusion(MP). The new strategies for static cold storage are mainly designed to increase the fatty liver graft preservation via the supplementation of commercial organ preservation solutions with additives. In this paper we stress the importance of carrying out effective graft washout after static cold preservation, and present a detailed discussion of the future perspectives for dynamic graft preservation using MP at different temperatures(hypothermia at 4 ℃, normothermia a t 3 7 ℃ and subnormothermia at 20 ℃- 2 5 ℃). Finally, we highlight some emerging applications of regenerative medicine in liver graft preservation. In conclusion, this review discusses the "state of the art" and future perspectives in static and dynamic liver graft preservation in order to improve graft viability.展开更多
The control of turbulence by dimples/pimples has drawn more and more attention. The objective of this paper is to investigate the effectiveness of the active dimples/pimples for the drag reduction in the incompressibl...The control of turbulence by dimples/pimples has drawn more and more attention. The objective of this paper is to investigate the effectiveness of the active dimples/pimples for the drag reduction in the incompressible turbulent flow. Firstly, the drag reduction by the opposition control based on active dimples/pimples at the lower wall is studied via the direct numerical simulation of the turbulent channel flow. It is found that large active dimples/pimples can not suppress the streamwise vortices significantly and thus almost no drag reduction is achieved. Small active dimples and pimples with the diameter of one fourth of the streak width can both reduce the friction drag, but pimples will induce a larger pressure drag than dimples. Then the suboptimal control scheme is examined based on small active dimples using the spanwise wall shear information only, It is shown that the friction drag decreases by about 4.5% but the total drag is only reduced by about 2.7% abated by the pressure drag. Compared with the actuation of the all-point blowing/suction or the all-point wall movement, the effectiveness of the turbulent drag reduction based on active shallow dimples is much smaller.展开更多
The dynamics of a rotating tethered satellite system （TSS） in the vicinity of libration points are highly nonlinear and inherently unstable. In order to fulfill the station-keep control of the rotating TSS along hal...The dynamics of a rotating tethered satellite system （TSS） in the vicinity of libration points are highly nonlinear and inherently unstable. In order to fulfill the station-keep control of the rotating TSS along halo orbits, a nonlinear output tracking control scheme based on the θ- D technique is proposed. Compared with the popular time-variant linear quadratic regulator （LQR） controller, this approach overcomes some limitations such as on-line computations of the algebraic Riccati equation. Besides, the obtained nonlinear suboptimal controller is in a closed form and easy to implement. Numerical simulations show that the TTS trajectories track the periodic reference orbit with low energy consumption in the presence of both tether and initial injection errors. The axis of rotation can keep pointing to an inertial specific object to fulfill an observation mission. In addition, the thrusts required by the controller are in an acceptable range and can be implemented through some low-thrust propulsion devices.展开更多
AIM:To examine the efficacy of telbivudine(LdT)+adefovir(ADV)vs continuation of lamivudine(LAM)+ADV in patients with LAM-resistant chronic hepatitis B(CHB)who show a suboptimal response to LAM+ADV.METHODS:This was a r...AIM:To examine the efficacy of telbivudine(LdT)+adefovir(ADV)vs continuation of lamivudine(LAM)+ADV in patients with LAM-resistant chronic hepatitis B(CHB)who show a suboptimal response to LAM+ADV.METHODS:This was a randomized,active-control,open-label,single-center,parallel trial.All eligible patients were enrolled in this study in Severance Hospital,Yonsei University College of Medicine,Seoul,South Korea,between March 2010 and March 2011.Hepatitis Be antigen(HBeAg)-positive CHB patients whose serum hepatitis B virus(HBV)DNA remained detectable despite at least 6 mo of LAM+ADV therapy were included.Enrolled patients were randomized to either switching to LdT(600 mg/d orally)plus ADV(10 mg/d orally)(LdT+ADV group)or to continuation with LAM(100 mg/d orally)plus ADV(10 mg/d orally)(LAM+ADV group),and were followed for 48 wk.One hundred and six patients completed the 48-wk treatment period.Serum HBV DNA,HBeAg status,liver biochemistry and safety were monitored at baseline and week 12,24,36 and 48.RESULTS:The duration of prior LAM+ADV treatment was 18.3(LdT+ADV)and 14.9 mo(LAM+ADV),respectively(P=0.131).No difference was seen in baseline serum HBV DNA between the two groups[3.66(LdT+ADV)vs 3.76(LAM+ADV)log10IU/mL,P=0.729].At week 48,although there was no significant difference in the mean reduction of serum HBV DNA from baseline between LdT+ADV group and LAM+ADV group(-0.81 vs-0.47 log10IU/mL,P=0.167),more patients in the LdT+ADV group had undetectable HBV DNA levels compared to those in the LAM+ADV group(30.2%vs 11.5%,P=0.019).Three patients with LdT+ADV treatment and 2 patients with LAM+ADV treatment achieved HBeAg loss.The patients in both groups tolerated the treatment well without serious adverse events.The proportion of patients with estimated glomerular filtration rate≥90 mL/min per 1.73 m2in the LdT+ADV group increased from 49.1%(26/53)at baseline to 58.5%(31/53)at week 48,while that in the LAM+ADV group decreased from 37.7%(20/53)at baseline to 30.2%(16/53)at week 48.CONCLUSION:The switch to LdT+ADV in su展开更多
The missile autopilot for an interceptor with tail fins and pulse thrusters is designed via the θ-D approach. The nonlin- ear dynamic model of the pitch and yaw motion of the missile is transformed into a linear-like...The missile autopilot for an interceptor with tail fins and pulse thrusters is designed via the θ-D approach. The nonlin- ear dynamic model of the pitch and yaw motion of the missile is transformed into a linear-like structure with state-dependent coef- ficient （SDC） matrices. Based on the linear-like structure, a θ-D feedback controller is designed to steer the missile to track refer- ence acceleration commands. A sufficient condition that ensures the asymptotic stability of the tracking system is given based on Lyapunov＇s theorem. Numerical results show that the proposed autopilot achieves good tracking performance and the closed-loop tracking system is asymptotically stable.展开更多
The pathology of Alzheimer’s disease involves a long preclinical period,where the characteristic clinical symptoms of the changes in the brain are undetectable.During the preclinical period,homeostatic mechanisms may...The pathology of Alzheimer’s disease involves a long preclinical period,where the characteristic clinical symptoms of the changes in the brain are undetectable.During the preclinical period,homeostatic mechanisms may help prevent widespread cell death.Evidence has pointed towards selective cell death of diseased neurons playing a potentially protective role.As the disease progresses,dysregulation of signaling pathways that govern cell death contributes to neurodegeneration.Aberrant activation of the c-Jun N-terminal kinase pathway has been established in human and animal models of Alzheimer’s disease caused by amyloid-beta 42-or tau-mediated neurodegeneration.Clonal mosaic studies in Drosophila that examine amyloid-beta 42 in a subset of neurons suggest complex interplay between amyloid-beta 42-expressing and wild-type cells.This review examines the role of c-Jun N-terminal kinase signaling in the context of cell competition and short-range signaling interactions between amyloid-beta 42-expressing and wild-type neurons.Cell competition is a conserved phenomenon regulating tissue integrity by assessing the fitness of cells relative to their neighbors and eliminating suboptimal cells.Somatic clones of amyloid-beta 42 that juxtapose genetically distinct neuronal cell populations show promise for studying neurodegeneration.Generating genetic mosaics with labeled clones of amyloid-beta 42-or tau-expressing and wild-type neurons will allow us to understand how short-range signaling alterations trigger cell death in neurons and thereby contribute to the progression of Alzheimer’s disease.These approaches have the potential to uncover biomarkers for early Alzheimer’s disease detection and new therapeutic targets for intervention.展开更多
BACKGROUND Entecavir(ETV)is a potent and safe antiviral agent for patients with chronic hepatitis B(CHB);however,some patients may exhibit suboptimal response or resistance to ETV.Tenofovir alafenamide(TAF)is a novel ...BACKGROUND Entecavir(ETV)is a potent and safe antiviral agent for patients with chronic hepatitis B(CHB);however,some patients may exhibit suboptimal response or resistance to ETV.Tenofovir alafenamide(TAF)is a novel tenofovir prodrug with improved pharmacokinetics and reduced renal and bone toxicity compared with tenofovir disoproxil fumarate.AIM To evaluate the efficacy and safety of switching from ETV to TAF in patients with CHB exhibiting suboptimal response to ETV.METHODS A total of 60 patients with CHB who had been treated with ETV for at least 12 mo and had persistent or recurrent viremia[Hepatitis B virus(HBV)DNA≥20 IU/mL]or partial virologic response(HBV DNA<20 IU/mL,but detectable)were enrolled in the study.The patients were randomly assigned to either continue ETV(0.5 mg)daily or switch to TAF(25 mg)daily for 48 wk.The primary endpoint was the proportion of patients who achieved a virologic response(HBV DNA level<20 IU/mL)at week 48.Secondary endpoints included changes in serum alanine aminotransferase(ALT),hepatitis B surface antigen(HBsAg),hepatitis B e antigen(HBeAg),and anti-HBe levels,and renal and bone safety parameters.RESULTS At week 48,the proportion of patients who achieved a virologic response was significantly higher in the TAF group than in the ETV group(93.3%vs 66.7%,P=0.012).The mean reduction in HBV DNA from baseline was also significantly greater in the TAF group than in the ETV group(-3.8 vs-2.4 Log10 IU/mL,P<0.001).The rates of ALT normalization,HBeAg loss,HBeAg seroconversion,and HBsAg loss were not found to significantly differ between the two groups.None of the patients developed genotypic resistance to ETV or TAF.Both drugs were well tolerated,with no serious adverse events or discontinuations caused by adverse events.No significant changes were observed in the estimated glomerular filtration rate,serum creatinine level,or urine protein-to-creatinine ratio in either group.The TAF group had a significantly lower decrease in bone mineral density at the lumbar spine and hip than t展开更多
Ruxolitinib is a cornerstone of management for some subsets of myeloproliferative neoplasms(MPNs);however,a considerable number of patients respond suboptimally.Here,we evaluated the efficacy of micheliolide(MCL),a na...Ruxolitinib is a cornerstone of management for some subsets of myeloproliferative neoplasms(MPNs);however,a considerable number of patients respond suboptimally.Here,we evaluated the efficacy of micheliolide(MCL),a natural guaianolide sesquiterpene lactone,alone or in combination with ruxolitinib in samples from patients with MPNs,JAK2V617F-mutated MPN cell lines,and a Jak2V617F knock-in mouse model.MCL effectively suppressed colony formation of hematopoietic progenitors in samples from patients with MPNs and inhibited cell growth and survival of MPN cell lines in vitro.Co-treatment with MCL and ruxolitinib resulted in greater inhibitory effects compared with treatment with ruxolitinib alone.Moreover,dimethylaminomicheliolide(DMAMCL),an orally available derivative of MCL,significantly increased the efficacy of ruxolitinib in reducing splenomegaly and cytokine production in Jak2V617F knock-in mice without evident effects on normal hematopoiesis.Importantly,MCL could target the Jak2V617F clone and reduce mutant allele burden in vivo.Mechanistically,MCL can form a stable covalent bond with cysteine residues of STAT3/5 to suppress their phosphorylation,thus inhibiting JAK/STAT signaling.Overall,these findings suggest that MCL is a promising drug in combination with ruxolitinib in the setting of suboptimal response to ruxolitinib.展开更多
Chronic hepatitis B (CHB) is currently medically managed with either interferon-alpha or one of the five nucleos(t)ide analogs. However, there are still a large number of CHB patients whose response to the above thera...Chronic hepatitis B (CHB) is currently medically managed with either interferon-alpha or one of the five nucleos(t)ide analogs. However, there are still a large number of CHB patients whose response to the above therapies remains less than satisfactory, and their incomplete or non-response to antiviral therapies has plagued clinicians worldwide. In recent years, a newly proposed optimization therapy has provided us with a new approach to solve this problem. The key points in this optimization therapy are to initiate antiviral therapy with an appropriate agent at the correct time point, and to adjust treatments in patients with poor early responses by adding a second agent or switching to another more potent agent. In this review, we summarize recent developments in optimization therapy for the treatment of CHB, and provide an outlook for future research in this field. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.展开更多
The error of single step-ahead output prediction is the information traditionally used to correct the state estimate while exploiting the new measurement of the system output.However,its dynamics and statistical prope...The error of single step-ahead output prediction is the information traditionally used to correct the state estimate while exploiting the new measurement of the system output.However,its dynamics and statistical properties can be further studied and exploited in other ways.It is known that in the case of suboptimal state estimation,this output prediction error forms a correlated sequence,hence it can be effectively predicted in real time.Such a suboptimal scenario is typical in applications where the process noise model is not known or it is uncertain.Therefore,the paper deals with the problems of analytical and empirical modeling,identification,and prediction of the output error of the suboptimal state estimator for the sake of improving the output prediction accuracy and ultimately the performance of the model predictive control.The improvements are validated on an empirical model of type 1 diabetes within an in-silico experiment focused on glycemia prediction and implementation of the MPC-based artificial pancreas.展开更多
In this paper we propose an optimal method for solving the linear bilevel programming problem with no upper-level constraint. The main idea of this method is that the initial point which is in the feasible region goes...In this paper we propose an optimal method for solving the linear bilevel programming problem with no upper-level constraint. The main idea of this method is that the initial point which is in the feasible region goes forward along the optimal direction firstly. When the iterative point reaches the boundary of the feasible region, it can continue to go forward along the suboptimal direction. The iteration is terminated until the iterative point cannot go forward along the suboptimal direction and effective direction, and the new iterative point is the solution of the lower-level programming. An algorithm which bases on the main idea above is presented and the solution obtained via this algorithm is proved to be optimal solution to the bilevel programming problem. This optimal method is effective for solving the linear bilevel programming problem.展开更多
One of the challenges in civil engineering is to find an innovative means of suppressing the structural vibration due to earthquake and wind loadings. This paper presents an approach for effectively suppressing vibrat...One of the challenges in civil engineering is to find an innovative means of suppressing the structural vibration due to earthquake and wind loadings. This paper presents an approach for effectively suppressing vibrations of a structure with variable friction damper using a new Bang-Bang control input. A continuous function of story velocities is used to represent the improved control to reduce chatter, high frequency switching and avoid instability. With a genetic algorithm, the amplitudes of control and preloading friction forces individually prescribed in the controller and damper are optimized for enhancing the seismic performance of buildings. The control strategy for the friction damper is proposed for a three story building with one variable friction damper installed at the first story for seismic reduction. The numerical results indicate that a better reduction of peak response accelerations of floors can be achieved than those of the unmodified controller, and the adaptability of the control system is also improved greatly by comparison with the reduction ratios of the structural response energy excited by different earthquake intensities.展开更多
We investigate the close-range relative motion and control of a spacecraft approaching a tumbling target. Unlike the traditional rigid-body dynamics with translation and rotation about the center of mass（CM）, the ki...We investigate the close-range relative motion and control of a spacecraft approaching a tumbling target. Unlike the traditional rigid-body dynamics with translation and rotation about the center of mass（CM）, the kinematic coupling between translation and rotation is taken into consideration to directly describe the motion of the spacecraft＇s sensors or devices which are not coincident with the CM. Thus, a kinematically coupled 6 degrees-of-freedom（DOF） relative motion model for the instrument（feature point） is set up. To make the chaser spacecraft＇s feature point track the target＇s, an optimal tracking problem is defined and a control law with a feedback-feedforward structure is designed. With quasi-linearization of the nonlinear dynamical system, the feedforward term is computed from a specified constraint about the dynamical system and the reference model, and the feedback action is derived starting from the state-dependent Ricca equation（SDRE）. The proposed controller is compared with an existing suboptimal tracking controller, and numerical simulations are presented to illustrate the effectiveness and superiority of the proposed method.展开更多
This paper proposes a time-varying sliding mode control method to address nonlinear missile body kinematics based on the suboptimal control theory.The analytical solution of suboptimal time-varying sliding surface and...This paper proposes a time-varying sliding mode control method to address nonlinear missile body kinematics based on the suboptimal control theory.The analytical solution of suboptimal time-varying sliding surface and the corresponding suboptimal control law are obtained by solving the state-dependent Riccati equation analytically.Then,the Lyapunov method is used to analyze the motion trend in sliding surface and the asymptotic stability of the closed-loop system is validated.The suboptimal control law is transformed to the form of pseudo-angle-of-attack feedback.The simulation results indicate that the satisfactory performance can be obtained and the control law can overcome the influence of parameter errors.展开更多
This paper presents a novel conditionally suboptimal filtering algorithm on estimation problems that arise in discrete nonlinear time-varying stochastic difference systems. The suboptimal state estimate is formed by s...This paper presents a novel conditionally suboptimal filtering algorithm on estimation problems that arise in discrete nonlinear time-varying stochastic difference systems. The suboptimal state estimate is formed by summing of conditionally nonlinear filtering estimates that their weights depend only on time instants, in contrast to conditionally optimal filtering, the proposed conditionally suboptimal filtering allows parallel processing of information and reduce online computational requirements in some nonlinear stochastic difference system. High accuracy and efficiency of the conditionally suboptimal nonlinear filtering are demonstrated on a numerical example.展开更多
In this article, affine-quadratic control problems are studied. Error bounds are derived for the difference between the performance indices corresponding to the optimal and a class of suboptimal controls. In particula...In this article, affine-quadratic control problems are studied. Error bounds are derived for the difference between the performance indices corresponding to the optimal and a class of suboptimal controls. In particular, it is shown that the performance of these suboptimal controls is close to that of the optimal control whenever the error in estimating the costate initial condition is small.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 60572027)the Outstanding Young Researchers Foundation of Sichuan Province (Grant No. 03ZQ026-033)+1 种基金the Program for New Century Excellent Talents in University of China (Grant No. NCET-05-0794)the Young Teacher Foundation of Mechanical School (Grant No. MYF0806)
文摘Non-intrusive methods for eye tracking are important for many applications of vision-based human computer interaction. However, due to the high nonlinearity of eye motion, how to ensure the robust- ness of external interference and accuracy of eye tracking poses the primary obstacle to the integration of eye movements into today＇s interfaces. In this paper, we present a strong tracking finite-difference extended Kalman filter algorithm, aiming to overcome the difficulty in modeling nonlinear eye tracking. In filtering calculation, strong tracking factor is introduced to modify a priori covariance matrix and improve the accuracy of the filter. The filter uses finite-difference method to calculate partial derivatives of nonlinear functions for eye tracking. The latest experimental results show the validity of our method for eye tracking under realistic conditions.
基金Supported by National Science and Technology Support Program"Key Technology for male-sterile breeding of main vegetable cropsintegration and seed industrialization"(2008BADB1B04)SeedProject of Vegetable Germplasm and Breeding in Shandong Province"Start-up Funding of High-level Talents in Qingdao Agricultureuniversity"(630912)~~
文摘Objective The aim of this study was to explore the method and standard for rapidly screening low temperature-resistant pepper germplasm resources and provide a theoretical basis for the breeding of low temperature-resistant pepper. [ Method ] With 110 pigment pepper seeds as the materials, their germination vigor under optimum temperature and suboptimal temperature were determined by means of roll rapid germination, and seeds with different genetic types were evaluated from aspects of germination vigor and its interval division. [ Result ] 37 pepper seeds with stronger low temperature resistance were screened. [ Conclusion]This study provides an important basis for screening low temperature-resistant pepper germplasm resources.
基金supported in part by the Australian Research Council Discovery Early Career Researcher Award(DE200101128)Australian Research Council(DP190101557)。
文摘In this paper,an adaptive dynamic programming(ADP)strategy is investigated for discrete-time nonlinear systems with unknown nonlinear dynamics subject to input saturation.To save the communication resources between the controller and the actuators,stochastic communication protocols(SCPs)are adopted to schedule the control signal,and therefore the closed-loop system is essentially a protocol-induced switching system.A neural network(NN)-based identifier with a robust term is exploited for approximating the unknown nonlinear system,and a set of switch-based updating rules with an additional tunable parameter of NN weights are developed with the help of the gradient descent.By virtue of a novel Lyapunov function,a sufficient condition is proposed to achieve the stability of both system identification errors and the update dynamics of NN weights.Then,a value iterative ADP algorithm in an offline way is proposed to solve the optimal control of protocol-induced switching systems with saturation constraints,and the convergence is profoundly discussed in light of mathematical induction.Furthermore,an actor-critic NN scheme is developed to approximate the control law and the proposed performance index function in the framework of ADP,and the stability of the closed-loop system is analyzed in view of the Lyapunov theory.Finally,the numerical simulation results are presented to demonstrate the effectiveness of the proposed control scheme.
基金Supported by Grant from Fondo de Investigaciones Sanitarias,No.FIS PI12/00519Eirini Pantazi is the recipient of a fellowship from Agència de Gestiód’Ajuts Universitaris i de Recerca,No.2012FI_B00382,Generalitat de Catalunya,Barcelona,Spain
文摘The urgent need to expand the donor pool in order to attend to the growing demand for liver transplantation has obliged physicians to consider the use of suboptimal liver grafts and also to redefine the preservation strategies. This review examines the different methods of liver graft preservation, focusing on the latest advances in both static cold storage and machine perfusion(MP). The new strategies for static cold storage are mainly designed to increase the fatty liver graft preservation via the supplementation of commercial organ preservation solutions with additives. In this paper we stress the importance of carrying out effective graft washout after static cold preservation, and present a detailed discussion of the future perspectives for dynamic graft preservation using MP at different temperatures(hypothermia at 4 ℃, normothermia a t 3 7 ℃ and subnormothermia at 20 ℃- 2 5 ℃). Finally, we highlight some emerging applications of regenerative medicine in liver graft preservation. In conclusion, this review discusses the "state of the art" and future perspectives in static and dynamic liver graft preservation in order to improve graft viability.
基金Project supported by the National Natural Science Foun-dation of China(Grant Nos.11402088,51376062)
文摘The control of turbulence by dimples/pimples has drawn more and more attention. The objective of this paper is to investigate the effectiveness of the active dimples/pimples for the drag reduction in the incompressible turbulent flow. Firstly, the drag reduction by the opposition control based on active dimples/pimples at the lower wall is studied via the direct numerical simulation of the turbulent channel flow. It is found that large active dimples/pimples can not suppress the streamwise vortices significantly and thus almost no drag reduction is achieved. Small active dimples and pimples with the diameter of one fourth of the streak width can both reduce the friction drag, but pimples will induce a larger pressure drag than dimples. Then the suboptimal control scheme is examined based on small active dimples using the spanwise wall shear information only, It is shown that the friction drag decreases by about 4.5% but the total drag is only reduced by about 2.7% abated by the pressure drag. Compared with the actuation of the all-point blowing/suction or the all-point wall movement, the effectiveness of the turbulent drag reduction based on active shallow dimples is much smaller.
基金supported by the National Natural Science Foundation of China (No.61174200)
文摘The dynamics of a rotating tethered satellite system （TSS） in the vicinity of libration points are highly nonlinear and inherently unstable. In order to fulfill the station-keep control of the rotating TSS along halo orbits, a nonlinear output tracking control scheme based on the θ- D technique is proposed. Compared with the popular time-variant linear quadratic regulator （LQR） controller, this approach overcomes some limitations such as on-line computations of the algebraic Riccati equation. Besides, the obtained nonlinear suboptimal controller is in a closed form and easy to implement. Numerical simulations show that the TTS trajectories track the periodic reference orbit with low energy consumption in the presence of both tether and initial injection errors. The axis of rotation can keep pointing to an inertial specific object to fulfill an observation mission. In addition, the thrusts required by the controller are in an acceptable range and can be implemented through some low-thrust propulsion devices.
基金Supported by A Grant under the Bilateral International Collaborative R and D Program from the Ministry of Knowledge Economythe Korea Healthcare Technology R and D Project,Ministry for Health and Welfare,South Korea,No.A102065+1 种基金the Liver Cirrhosis Clinical Research Center,a grant from the Korea Healthcare Technology R and D project,Ministry of Health and Welfare,South Korea,No.HI10C2020a grant to the Bilateral International Collaborative R and D Program from the Ministry of Trade,Industry and Energy,South Korea
文摘AIM:To examine the efficacy of telbivudine(LdT)+adefovir(ADV)vs continuation of lamivudine(LAM)+ADV in patients with LAM-resistant chronic hepatitis B(CHB)who show a suboptimal response to LAM+ADV.METHODS:This was a randomized,active-control,open-label,single-center,parallel trial.All eligible patients were enrolled in this study in Severance Hospital,Yonsei University College of Medicine,Seoul,South Korea,between March 2010 and March 2011.Hepatitis Be antigen(HBeAg)-positive CHB patients whose serum hepatitis B virus(HBV)DNA remained detectable despite at least 6 mo of LAM+ADV therapy were included.Enrolled patients were randomized to either switching to LdT(600 mg/d orally)plus ADV(10 mg/d orally)(LdT+ADV group)or to continuation with LAM(100 mg/d orally)plus ADV(10 mg/d orally)(LAM+ADV group),and were followed for 48 wk.One hundred and six patients completed the 48-wk treatment period.Serum HBV DNA,HBeAg status,liver biochemistry and safety were monitored at baseline and week 12,24,36 and 48.RESULTS:The duration of prior LAM+ADV treatment was 18.3(LdT+ADV)and 14.9 mo(LAM+ADV),respectively(P=0.131).No difference was seen in baseline serum HBV DNA between the two groups[3.66(LdT+ADV)vs 3.76(LAM+ADV)log10IU/mL,P=0.729].At week 48,although there was no significant difference in the mean reduction of serum HBV DNA from baseline between LdT+ADV group and LAM+ADV group(-0.81 vs-0.47 log10IU/mL,P=0.167),more patients in the LdT+ADV group had undetectable HBV DNA levels compared to those in the LAM+ADV group(30.2%vs 11.5%,P=0.019).Three patients with LdT+ADV treatment and 2 patients with LAM+ADV treatment achieved HBeAg loss.The patients in both groups tolerated the treatment well without serious adverse events.The proportion of patients with estimated glomerular filtration rate≥90 mL/min per 1.73 m2in the LdT+ADV group increased from 49.1%(26/53)at baseline to 58.5%(31/53)at week 48,while that in the LAM+ADV group decreased from 37.7%(20/53)at baseline to 30.2%(16/53)at week 48.CONCLUSION:The switch to LdT+ADV in su
基金supported by the National Natural Science Foundation of China(61174203)the Aeronautical Science Foundation of China(20110177002)
文摘The missile autopilot for an interceptor with tail fins and pulse thrusters is designed via the θ-D approach. The nonlin- ear dynamic model of the pitch and yaw motion of the missile is transformed into a linear-like structure with state-dependent coef- ficient （SDC） matrices. Based on the linear-like structure, a θ-D feedback controller is designed to steer the missile to track refer- ence acceleration commands. A sufficient condition that ensures the asymptotic stability of the tracking system is given based on Lyapunov＇s theorem. Numerical results show that the proposed autopilot achieves good tracking performance and the closed-loop tracking system is asymptotically stable.
基金supported by 1RO1EY032959-01,NIH1R15GM124654-01 from NIHSchuellein Chair Endowment Fund and STEM Catalyst Grant and start-up support from the University of Dayton(to AS,MKS is Co-PI on NIH RO1 and Co-I on NIH R15)。
文摘The pathology of Alzheimer’s disease involves a long preclinical period,where the characteristic clinical symptoms of the changes in the brain are undetectable.During the preclinical period,homeostatic mechanisms may help prevent widespread cell death.Evidence has pointed towards selective cell death of diseased neurons playing a potentially protective role.As the disease progresses,dysregulation of signaling pathways that govern cell death contributes to neurodegeneration.Aberrant activation of the c-Jun N-terminal kinase pathway has been established in human and animal models of Alzheimer’s disease caused by amyloid-beta 42-or tau-mediated neurodegeneration.Clonal mosaic studies in Drosophila that examine amyloid-beta 42 in a subset of neurons suggest complex interplay between amyloid-beta 42-expressing and wild-type cells.This review examines the role of c-Jun N-terminal kinase signaling in the context of cell competition and short-range signaling interactions between amyloid-beta 42-expressing and wild-type neurons.Cell competition is a conserved phenomenon regulating tissue integrity by assessing the fitness of cells relative to their neighbors and eliminating suboptimal cells.Somatic clones of amyloid-beta 42 that juxtapose genetically distinct neuronal cell populations show promise for studying neurodegeneration.Generating genetic mosaics with labeled clones of amyloid-beta 42-or tau-expressing and wild-type neurons will allow us to understand how short-range signaling alterations trigger cell death in neurons and thereby contribute to the progression of Alzheimer’s disease.These approaches have the potential to uncover biomarkers for early Alzheimer’s disease detection and new therapeutic targets for intervention.
基金Study on the efficacy and safety of tenofovir alafenamide in treating chronic hepatitis B patients with poor entecavir response,No.SKJP22020201008.
文摘BACKGROUND Entecavir(ETV)is a potent and safe antiviral agent for patients with chronic hepatitis B(CHB);however,some patients may exhibit suboptimal response or resistance to ETV.Tenofovir alafenamide(TAF)is a novel tenofovir prodrug with improved pharmacokinetics and reduced renal and bone toxicity compared with tenofovir disoproxil fumarate.AIM To evaluate the efficacy and safety of switching from ETV to TAF in patients with CHB exhibiting suboptimal response to ETV.METHODS A total of 60 patients with CHB who had been treated with ETV for at least 12 mo and had persistent or recurrent viremia[Hepatitis B virus(HBV)DNA≥20 IU/mL]or partial virologic response(HBV DNA<20 IU/mL,but detectable)were enrolled in the study.The patients were randomly assigned to either continue ETV(0.5 mg)daily or switch to TAF(25 mg)daily for 48 wk.The primary endpoint was the proportion of patients who achieved a virologic response(HBV DNA level<20 IU/mL)at week 48.Secondary endpoints included changes in serum alanine aminotransferase(ALT),hepatitis B surface antigen(HBsAg),hepatitis B e antigen(HBeAg),and anti-HBe levels,and renal and bone safety parameters.RESULTS At week 48,the proportion of patients who achieved a virologic response was significantly higher in the TAF group than in the ETV group(93.3%vs 66.7%,P=0.012).The mean reduction in HBV DNA from baseline was also significantly greater in the TAF group than in the ETV group(-3.8 vs-2.4 Log10 IU/mL,P<0.001).The rates of ALT normalization,HBeAg loss,HBeAg seroconversion,and HBsAg loss were not found to significantly differ between the two groups.None of the patients developed genotypic resistance to ETV or TAF.Both drugs were well tolerated,with no serious adverse events or discontinuations caused by adverse events.No significant changes were observed in the estimated glomerular filtration rate,serum creatinine level,or urine protein-to-creatinine ratio in either group.The TAF group had a significantly lower decrease in bone mineral density at the lumbar spine and hip than t
基金Supported in part by Haihe Laboratory of Cell Ecosystem Innovation Fund(22HHXBSS00033)CAMS Initiative Fund for Medical Sciences(Nos.2022-I2M-1-022)+1 种基金Clinical Research Fund of National Clinical Research Centre for Blood Diseases(Nos.2023NCRCA0117 and 2023NCRCA0103)National Natural Science Funds(Nos.82170139,82104785,82070134 and 81530008).
文摘Ruxolitinib is a cornerstone of management for some subsets of myeloproliferative neoplasms(MPNs);however,a considerable number of patients respond suboptimally.Here,we evaluated the efficacy of micheliolide(MCL),a natural guaianolide sesquiterpene lactone,alone or in combination with ruxolitinib in samples from patients with MPNs,JAK2V617F-mutated MPN cell lines,and a Jak2V617F knock-in mouse model.MCL effectively suppressed colony formation of hematopoietic progenitors in samples from patients with MPNs and inhibited cell growth and survival of MPN cell lines in vitro.Co-treatment with MCL and ruxolitinib resulted in greater inhibitory effects compared with treatment with ruxolitinib alone.Moreover,dimethylaminomicheliolide(DMAMCL),an orally available derivative of MCL,significantly increased the efficacy of ruxolitinib in reducing splenomegaly and cytokine production in Jak2V617F knock-in mice without evident effects on normal hematopoiesis.Importantly,MCL could target the Jak2V617F clone and reduce mutant allele burden in vivo.Mechanistically,MCL can form a stable covalent bond with cysteine residues of STAT3/5 to suppress their phosphorylation,thus inhibiting JAK/STAT signaling.Overall,these findings suggest that MCL is a promising drug in combination with ruxolitinib in the setting of suboptimal response to ruxolitinib.
基金Supported by The National Twelve-Five Project of China,No.2012ZX10002007-001-003,and No.2013ZX10002001
文摘Chronic hepatitis B (CHB) is currently medically managed with either interferon-alpha or one of the five nucleos(t)ide analogs. However, there are still a large number of CHB patients whose response to the above therapies remains less than satisfactory, and their incomplete or non-response to antiviral therapies has plagued clinicians worldwide. In recent years, a newly proposed optimization therapy has provided us with a new approach to solve this problem. The key points in this optimization therapy are to initiate antiviral therapy with an appropriate agent at the correct time point, and to adjust treatments in patients with poor early responses by adding a second agent or switching to another more potent agent. In this review, we summarize recent developments in optimization therapy for the treatment of CHB, and provide an outlook for future research in this field. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.
基金supported by the grant VEGA 1/0049/20—Modelling and Control of Biosystems,the Ministry of Education,Science,Development and Sport of the Slovak Republic.
文摘The error of single step-ahead output prediction is the information traditionally used to correct the state estimate while exploiting the new measurement of the system output.However,its dynamics and statistical properties can be further studied and exploited in other ways.It is known that in the case of suboptimal state estimation,this output prediction error forms a correlated sequence,hence it can be effectively predicted in real time.Such a suboptimal scenario is typical in applications where the process noise model is not known or it is uncertain.Therefore,the paper deals with the problems of analytical and empirical modeling,identification,and prediction of the output error of the suboptimal state estimator for the sake of improving the output prediction accuracy and ultimately the performance of the model predictive control.The improvements are validated on an empirical model of type 1 diabetes within an in-silico experiment focused on glycemia prediction and implementation of the MPC-based artificial pancreas.
基金"985 Program"Graduate Innovation Fund(20080112)of Jilin University
文摘In this paper we propose an optimal method for solving the linear bilevel programming problem with no upper-level constraint. The main idea of this method is that the initial point which is in the feasible region goes forward along the optimal direction firstly. When the iterative point reaches the boundary of the feasible region, it can continue to go forward along the suboptimal direction. The iteration is terminated until the iterative point cannot go forward along the suboptimal direction and effective direction, and the new iterative point is the solution of the lower-level programming. An algorithm which bases on the main idea above is presented and the solution obtained via this algorithm is proved to be optimal solution to the bilevel programming problem. This optimal method is effective for solving the linear bilevel programming problem.
基金The project supported by the National Science Fund for Distinguished Young Scholars(50025823).
文摘One of the challenges in civil engineering is to find an innovative means of suppressing the structural vibration due to earthquake and wind loadings. This paper presents an approach for effectively suppressing vibrations of a structure with variable friction damper using a new Bang-Bang control input. A continuous function of story velocities is used to represent the improved control to reduce chatter, high frequency switching and avoid instability. With a genetic algorithm, the amplitudes of control and preloading friction forces individually prescribed in the controller and damper are optimized for enhancing the seismic performance of buildings. The control strategy for the friction damper is proposed for a three story building with one variable friction damper installed at the first story for seismic reduction. The numerical results indicate that a better reduction of peak response accelerations of floors can be achieved than those of the unmodified controller, and the adaptability of the control system is also improved greatly by comparison with the reduction ratios of the structural response energy excited by different earthquake intensities.
基金Project supported by the Major Program of the National Natural Science Foundation of China(Grant Nos.61690210 and 61690213)
文摘We investigate the close-range relative motion and control of a spacecraft approaching a tumbling target. Unlike the traditional rigid-body dynamics with translation and rotation about the center of mass（CM）, the kinematic coupling between translation and rotation is taken into consideration to directly describe the motion of the spacecraft＇s sensors or devices which are not coincident with the CM. Thus, a kinematically coupled 6 degrees-of-freedom（DOF） relative motion model for the instrument（feature point） is set up. To make the chaser spacecraft＇s feature point track the target＇s, an optimal tracking problem is defined and a control law with a feedback-feedforward structure is designed. With quasi-linearization of the nonlinear dynamical system, the feedforward term is computed from a specified constraint about the dynamical system and the reference model, and the feedback action is derived starting from the state-dependent Ricca equation（SDRE）. The proposed controller is compared with an existing suboptimal tracking controller, and numerical simulations are presented to illustrate the effectiveness and superiority of the proposed method.
基金supported by the China Postdoctoral Science Foundation(2017M620863).
文摘This paper proposes a time-varying sliding mode control method to address nonlinear missile body kinematics based on the suboptimal control theory.The analytical solution of suboptimal time-varying sliding surface and the corresponding suboptimal control law are obtained by solving the state-dependent Riccati equation analytically.Then,the Lyapunov method is used to analyze the motion trend in sliding surface and the asymptotic stability of the closed-loop system is validated.The suboptimal control law is transformed to the form of pseudo-angle-of-attack feedback.The simulation results indicate that the satisfactory performance can be obtained and the control law can overcome the influence of parameter errors.
文摘This paper presents a novel conditionally suboptimal filtering algorithm on estimation problems that arise in discrete nonlinear time-varying stochastic difference systems. The suboptimal state estimate is formed by summing of conditionally nonlinear filtering estimates that their weights depend only on time instants, in contrast to conditionally optimal filtering, the proposed conditionally suboptimal filtering allows parallel processing of information and reduce online computational requirements in some nonlinear stochastic difference system. High accuracy and efficiency of the conditionally suboptimal nonlinear filtering are demonstrated on a numerical example.
文摘In this article, affine-quadratic control problems are studied. Error bounds are derived for the difference between the performance indices corresponding to the optimal and a class of suboptimal controls. In particular, it is shown that the performance of these suboptimal controls is close to that of the optimal control whenever the error in estimating the costate initial condition is small.
