State Of System Research Articles

Nonlinear Kalman filter for gyroscopic and accelerometer noise rejection of an unmanned aerial vehicle control strategy

This study addresses timing issues inherent in traditional proportional-integral-derivative (PID) controllers for drone angle control and introduces an innovative solution, the adaptive PID flight controller, aimed at optimizing PID gains for improved performance in terms of speed, accuracy, and stability. To enhance the controller's robustness against noise and accurately estimate the system's state, a Kalman filter is incorporated. This filtering mechanism is designed to reject noise and provide precise state estimation, thereby contributing to the overall effectiveness of the adaptive PID flight controller in managing altitude dynamics for unmanned aerial vehicles (UAVs). The comparative methodology evaluates three configurations: a single PID controller for all three angles, two PID controllers dedicated to pitch/roll and yaw angles separately, and three PID sub-controllers for each angle (pitch, roll, and yaw). The study seeks to identify the most effective PID configuration in terms of stability, responsiveness, and accuracy while highlighting the added benefits of noise rejection and state estimation through the Kalman filter. This integrated approach showcases innovation and effectiveness, introducing a comprehensive solution not explored in previous research.

Robust optimal control for uncertain wheeled mobile robot based on reinforcement learning: ADP approach

This paper presents a robust optimal control approach for the wheel mobile robot system, which considers the effects of external disturbances, uncertainties, and wheel slipping. The proposed method utilizes an adaptive dynamic programming (ADP) technique in conjunction with a disturbance observer. Initially, the system's state space model is formulated through the utilization of kinematic and dynamic models. Subsequently, the ADP method is employed to establish an online adaptive optimal controller, which solely relies on a single neural network for the purpose of function approximation. The utilization of the disturbance observer in conjunction with the compensation controller serves to alleviate the effects of disturbances. The Lyapunov theorem establishes the stability of the complete closed-loop system and the convergence of the weights of the neural network. The proposed approach has been shown to be effective through simulation under the effect of the disturbances and the change of the desired trajectory.

Development of a fed-batch-scale anaerobic co-digestion control system based on multivariable output error state space and model predictive control

This paper describes a feeding control system for fed-batch-scale anaerobic co-digestion. The proposed system is based on the multivariable output error state space and uses model predictive control to regulate the biogas flow output of anaerobic co-digestion. This control system combines predictive modeling, receding-horizon optimization, and state feedback. An accurate linear model of anaerobic co-digestion is obtained through the multivariable output error state space method using experimental data, and the accuracy of the model is evaluated using a goodness-of-fit index and the root mean square error. After augmenting the model, a predictive control system is established. The system states are observed through a Kalman filter, and the constrained receding-horizon optimization problem is solved using quadratic programming. Finally, the stability of the control system is demonstrated from both open- and closed-loop perspectives. The control system is then constructed and used in actual experiments, with the target flow output set at 100 NmL/h. The final flow output indicates that the control system achieves good control performance. This research enables the biogas output of anaerobic co-digestion to be controlled from a linear perspective through a concise control algorithm with strong practical application prospects.

Hückel molecular orbital theory on a quantum computer: A scalable system-agnostic variational implementation with compact encoding.

Hückel molecular orbital (HMO) theory provides a semi-empirical treatment of the electronic structure in conjugated π-electronic systems. A scalable system-agnostic execution of HMO theory on a quantum computer is reported here based on a variational quantum deflation (VQD) algorithm for excited state quantum simulation. A compact encoding scheme is proposed here that provides an exponential advantage over the direct mapping and allows for quantum simulation of the HMO model for systems with up to 2n conjugated centers with n qubits. The transformation of the Hückel Hamiltonian to qubit space is achieved by two different strategies: an iterative refinement transformation and the Frobenius-inner-product-based transformation. These methods are tested on a series of linear, cyclic, and hetero-nuclear conjugated π-electronic systems. The molecular orbital energy levels and wavefunctions from the quantum simulation are in excellent agreement with the exact classical results. However, the higher excited states of large systems are found to suffer from error accumulation in the VQD simulation. This is mitigated by formulating a variant of VQD that exploits the symmetry of the Hamiltonian. This strategy has been successfully demonstrated for the quantum simulation of C60 fullerene containing 680 Pauli strings encoded on six qubits. The methods developed in this work are easily adaptable to similar problems of different complexity in other fields of research.

Data-driven estimation of the algebraic Riccati equation for the discrete-time inverse linear quadratic regulator problem

In this paper, we propose a method for estimating the algebraic Riccati equation (ARE) with respect to an unknown discrete-time system from the system state and input observation. The inverse optimal control (IOC) problem asks, “What objective function is optimized by a given control system?” The inverse linear quadratic regulator (ILQR) problem is an IOC problem that assumes a linear system and quadratic objective function. The ILQR problem can be solved by solving a linear matrix inequality that contains the ARE. However, the system model is required to obtain the ARE, and it is often unknown in fields in which the IOC problem occurs, for example, biological system analysis. Our method directly estimates the ARE from the observation data without identifying the system. This feature enables us to economize the observation data using prior information about the objective function. We provide a data condition that is sufficient for our method to estimate the ARE. We conducted a numerical experiment to demonstrate that our method can estimate the ARE with less data than system identification if the prior information is sufficient.

Optimizing the functional state of the cardiorespiratory system of female students aged 17-19 with the help of a modified program of distance classes in physical education

The article deals with the peculiarities of the impact of a modified program of distance training on physical education on the functional state of circulatory systems and external breathing of students of 17-19 years of higher education. The relevance and practical importance of this study is due to the complex modern conditions of life of our country, the inability to conduct full -fledged classes among student youth and the need to maintain the optimal level of physical and functional state of student youth. The use among female students of the experimental group of the program of remote classes proposed by us contributed to significantly higher rates of improvement in heart rate, all types of blood pressure, Robinson's index, total peripheral resistance of blood vessels, coefficient of efficiency of blood circulation, vital capacity of the lungs (in 2-3 times), breath retention time on inhalation and exhalation (3 and 5 times, respectively), Skibinsky index 5 times, hypoxia index (20 times) and almost 5 times the levels of the functional state of the cardiovascular system and the external system breath. The results of changes in their intragroup distribution by the levels of levels of functional state of circulatory and external respiration, which were reflected in the increase of their representation in functional classes high and above average, were significantly more optimal in the experimental group. Similar changes in the girls of the control group were insignificant. The results testified to the high efficiency of the proposed program of distance classes with the use of fitness and the possibility of its practical use among students of higher education.

Influence of distance section classes on aesthetic gymnastics on the physical condition of students of 18-19 years of higher education institution

The article deals with the possibility of using aesthetic gymnastics in the program of remote section classes among students of 18-19 years of higher education. The relevance and practical significance of this study is due to the need to improve the overall physical condition of the student youth, especially in recent years, which are characterized by the unjustified transition of many universities of Ukraine mainly to the sectional form of work with students, the consequences of the world pandemic at the Covid-19 and the military condition. In connection with the above, an evaluation of the use of aesthetic gymnastics tools was used in the program of sectional distance classes of students of higher education. It is proved that the use of the studio girls of the said program contributed to a significant improvement in their overall physical condition. The completion of the study was a significant increase in the levels of functional state of circulatory systems and external respiration (respectively by 36.37%and 26.33%), physical health (by 27.97%), physical work capacity (by 33.13%), weight loss (by 3.74%), values of deviation of body weight from proper values (by 7.63%), fat component (by 20.27%) and score for the type of body construction (by 15.57%). The results testified to the high efficiency of the use of aesthetic gymnastics in the program of section remote classes for students of higher education institution and the possibility of practical use in the boiling process of higher education in physical education.

Neural network-based prescribed performance tracking control for a class of nonlinear systems with mismatched disturbances

This paper addresses the prescribed performance tracking control problem for a class of nonlinear systems subject to mismatched uncertainties. A novel disturbance observer-based control (DOBC) scheme is proposed through combining radial basis function neural network (RBFNN) and prescribed performance function (PPF). In contrast to traditional DOBC, the proposed approach employs RBFNN technology to approximate unknown nonlinear functions in the system, instead of treating them as part of lumped disturbances. A novel disturbance observer is developed to estimate disturbances characterised by a nonlinear exogenous system. To enhance control performance, a PPF that characterises both transient and steady-state behaviour is used for the transformation of tracking errors. It can be proved that all the states of the closed-loop system can be guaranteed to be uniformly ultimately bounded (UUB), and that the tracking error evolves within the prespecified boundaries. Theoretical results are validated and supported by two simulation examples.

Influence of medical-social and socio-economic factors on infant mortality rate in the Republic of Ingushetia

BACKGROUND: The infant mortality rate, as one of the indicators of the health and quality of life of the population, is an important factor that determines the country’s healthcare priorities. Despite the steadily decreasing infant mortality rates in the Russian Federation, the value of this indicator varies by region; thus, studying the factors influencing its value is relevant. If the leading medical, social, and socioeconomic factors that influence the level of infant mortality could be determined using data from a representative region (Republic of Ingushetia), the main directions for organizing measures aimed at reducing mortality among children in the first year of life will be identified. AIM: To determine the main medical, social and socio-economic factors that influence the infant mortality rate in the Republic of Ingushetia. MATERIALS AND METHODS: An observational single-center retrospective study was performed to examine the influence of medical, social, and socioeconomic factors on the mortality rate of children aged 1 year in the Republic of Ingushetia. The obtained data were compared with similar indicators for the Russian Federation as a whole and the North Caucasus Federal District. RESULTS: During the study period (2011–2019), significant changes were observed in infant mortality rates in the Republic of Ingushetia: infant mortality has decreased because of the age components, leading to the normal ratio of neonatal and post neonatal mortality. Rates of infant mortality from certain conditions arising in the perinatal period, congenital anomalies, and nervous system and circulatory system diseases have significantly decreased. The proportion of women admitted under the supervision of antenatal clinics in the early pregnancy (up to 12 weeks) has increased, the incidence of morbidity among pregnant women has decreased, and the proportion of normal births has been increasing. Although many medical organizations have employed a sufficient number of medical personnel, the coverage for biochemical screening has decreased, detection of malformations and biochemical abnormalities during prenatal diagnostics was low, medical personnel have low qualifications, and the shortage of obstetric and pediatric beds and pathology beds for newborns and premature infants was significant. A statistically significant dependence of the frequency of deaths of children aged 1 year on socioeconomic indicators−unemployment level, monetary income of the population, and housing conditions−was revealed. CONCLUSION: The main medical, social, and socioeconomic factors that influence infant mortality were analyzed using data from the Republic of Ingushetia. Positive and negative trends in the current state of the healthcare system of this republic have been identified.

System-bath correlations and finite-time operation enhance the efficiency of a dissipative quantum battery

Abstract The reduced state of a small system strongly coupled to a thermal bath may be athermal and used as a small battery once disconnected. The unitarily extractable energy (a.k.a ergotropy) will be negligible if the disconnecting process is too slow. To study the efficiency of this battery, we consider the cycle of disconnecting, extracting, and connecting the battery back to the bath. Efficiency, i.e., the ratio between ergotropy and connecting plus disconnecting work, is a function of disconnecting time. We consider the Caldeira-Leggett model of a quantum battery in two scenarios. In the first scenario, we assume that the discharged battery is uncorrelated to the bath when connecting back and find that the efficiency peaks at an optimal disconnecting time. In the second scenario, the discharged battery is correlated to the bath, and find that the optimal efficiency corresponds to an instantaneous disconnection. On top of these results, we analyze various thermodynamic quantities for these Caldeira-Leggett quantum batteries and express the first and second laws of thermodynamics for the cycles in simple form despite the system-bath initial correlations and strong coupling regime of the working device.

Exact time-evolving scattering states in open quantum-dot systems with an interaction: Discovery of time-evolving resonant states

Abstract We study exact time-evolving many-electron states of an open double quantum-dot system with an interdot Coulomb interaction. A systematic construction of the time-evolving states for arbitrary initial conditions is proposed. For any initial states of one- and two-electron plane waves on the electrical leads, we obtain exact solutions of the time-evolving scattering states, which converge to known stationary scattering eigenstates in the long-time limit. For any initial states of localized electrons on the quantum dots, we find exact time-evolving states of a new type, which we refer to as time-evolving resonant states. In contrast to stationary resonant states, whose wave functions spatially diverge and not normalizable, the time-evolving resonant states are normalizable since their wave functions are restricted to a finite space interval due to causality. The exact time-evolving resonant states enable us to calculate the time-dependence of the survival probability of electrons on the quantum dots for the system with the linearized dispersions. It decays exponentially in time on one side of an exponential point of resonance energies while, on the other side, it oscillates during the decay as a result of the interference of the two resonance energies.

Using LQR controller for vertical position control on EAST

Vertical position control is essential for stabilizing plasma with elongated configurations. The EAST tokamak is equipped with a set of in-vessel control (IC) coils dedicated to this purpose. Currently, a PD controller with fixed parameters is used for the vertical position control of EAST plasma. However, the response of the plasma in the vertical position changes with changes in plasma configuration, which can result in different control parameter requirements. It is essential to develop a model-based fast-tuning control algorithm for ensuring stability in the vertical position under different configurations. In this study, a model-based vertical position controller tuning method based on a linear quadratic regulator algorithm (LQR) is proposed. Compared with contemporary PD controllers, the proposed model-based LQR controller can enable adjusting controller parameters based on the response of the system, achieving stable control under different vertical position responses. In the EAST experiment, the model-based LQR controller achieved stable control under a shot with a continuously increasing growth rate and reached a maximum controllable vertical displacement growth rate of 968 s−1. The robustness of the system was also demonstrated in a free drift experiment. The new vertical displacement control method can be adapted to different system states and plasma configurations and improve the controllability and safety of future devices.

Sensorless Model Predictive Control of Permanent Magnet Synchronous Motors Using an Unscented Kalman Filter

This paper deals with the application of the Model Predictive Control (MPC) algorithm to the sensorless control of a Permanent Magnet Synchronous Motor (PMSM). The proposed estimation strategy, based on the unscented Kalman filter (UKF), uses only the measurement of the motor current for the online estimation of speed, rotor position and load torque. Information about the system state is fed into the MPC algorithm. The results verify the effectiveness and applicability of the proposed sensorless control technique. To demonstrate its real-world applicability, implementation in low-speed direct drive astronomy telescope mount systems is investigated. The outcomes of the implementation are thoroughly examined, leading to insightful conclusions drawn from the observed results. Through rigorous theoretical analysis and extensive simulation studies, this paper establishes a solid foundation for the proposed sensorless control technique. The results obtained from simulation studies and real-world applications underscore the efficacy and versatility of the proposed approach, offering valuable insights for the advancement of sensorless control strategies in motor applications. The main aim of this work is to demonstrate and validate the practical feasibility of combining two complex techniques, establishing that such an integration is not only possible but also effective in achieving the desired objectives.

Adaptive command filtered control for a class of nonlinear time delay systems with extreme learning machine

AbstractIn this paper, an extreme learning machine (ELM)‐based adaptive command filtered control method is investigated for a class of strict feedback nonlinear systems with unknown external disturbances and time delay. To begin with, the original system state equation is transformed into a new form on account of coordinate transformation. Subsequently, an ELM is adopted to approximate unknown functions which exist in the whole system states, without any prior knowledges of the ideal weight vectors and approximation errors. Secondly, a command filter is developed for the system under consideration, which can avoid the probem of “explosion of complexity” caused by repeated derivation of virtual control signals in traditional backstepping control. Meanwhile, error compensation signals are designed to conquer the shortcoming of a dynamic surface control (DSC) method. The combination of ELM and command filter technique has been used to construct corresponding controllers and adaptive laws. Effective handling of the impact of time delay terms is ensured through designing a novel Lyapunov–Krasovskii functional. The proposed strategy guarantees boundedness of all signals in the closed‐loop system and the tracking error asymptotically converges to a compact set around the origin. In the end, two continuous stirred tank reactors (CSTRs) are taken as example to further verify the efficiency of the put forward control method.

On the question of the concept of external functions in Ukraine and Hungary

The main goal of any state, as a socio-legal entity, is to ensure, protect, regulate, and guarantee social, public, and individual interests. And that’s why all attention is focused on the regulation of socially important spheres. Such directions in the theory of the state and law of Ukraine and the state-legal theory of Hungary traditionally have the name - functions of the state, which according to different definitions and approaches of both Ukrainian and Hungarian specialists can be interpreted as the main directions of activity. Although this definition is not the only one. Today, in the scientific literature, you can find different opinions about what functions are, what are the constituent elements, and what are the functions, according to which criteria to classify them. The doctrine of the functions of the modern state is traditionally considered as an integral part of state and general theoretical jurisprudence, because nowadays the questions of the functions of the state, the necessity of which relates to the transformation of the role of the state in society, are becoming increasingly relevant. The functioning of the state is a rather complex and dynamic process that requires theoretical understanding. This causes considerable effort and serious disagreement among scientists. In the process of research, it is relevant to consider the functions of the state in the philosophical-legal system of the conceptual provisions of the state-legal theory. Find out what are the different definitions of the function of the state and how they relate to each other. But the main thesis of this article is the issue of specifically external functions, which should be understood by this, which is their vocation. Their study is of particular importance at the time of revision of existing mechanisms under the influence of globalization fluctuations. But this direction is extremely important for Ukraine, which is at the stage of acute renewal of social spheres of life, including the state and legal sphere. In general, this scientific article attempts to demonstrate the different points of view of Ukrainian and Hungarian specialists for the expansion of scientific research on the issue of defining the concept of external functions, and thus to contribute to the general scientific base on the part of Ukrainian scientists.

Valuation of a financial claim contingent on the outcome of a quantum measurement

Abstract We consider a rational agent who at time 0 enters into a financial contract for which the payout is determined by a quantum measurement at some time T > 0. The state of the quantum system is given in the Heisenberg representation by a known density matrix p. How much will the agent be willing to pay at time 0 to enter into such a contract? In the case of a finite dimensional Hilbert space H, each such claim is represented by an observable X where the eigenvalues of X determine the amount paid if the corresponding outcome is obtained in the measurement. We prove, under reasonable axioms, that there exists a pricing state q which is equivalent to the physical state p such that the pricing function Π takes the linear form Π (X) = P_0T tr(q X) for any claim X, where P_0T is the one-period discount factor. By “equivalent” we mean that p and q share the same null space: thus, for any |ξ〉∈ H one has p|ξ〉 = 0 if and only if q|ξ〉 = 0. We introduce a class of optimization problems and solve for the optimal contract payout structure for a claim based on a given measurement. Then we consider the implications of the Kochen-Specker theorem in this setting and we look at the problem of forming portfolios of such contracts. Finally, we consider multi-period contracts.

INVESTIGATION OF THE EFFICIENCY OF NON-STEROIDAL ANTI-INFLAMMATORY VETERINARY MEDICINAL PRODUCT IN THE COMPLEX TREATMENT OF DISEASES OF THE MUSCULOSKELETAL SYSTEM OF PIGS

The article presents the results of clinical trials of a non-steroidal anti-inflammatory veterinary drug when administered to fattening piglets with clinical signs of musculoskeletal diseases. For the treatment of the diseases, piglets of the experimental (I) and control (II) groups received an antimicrobial drug based on the tetracycline antibiotic. The animals of the experimental group were additionally administered orally with drinking water the test non-steroidal anti-inflammatory drug based on acetylsalicylic, ascorbic and citric acids, in the recommended dosage by the manufacturer. Blood for laboratory tests was selected from piglets before and after the use of drugs. Studies of hematological and biochemical parameters were conducted according to generally accepted methods. The therapeutic efficiecy of the drug and its effect on the morphofunctional state of the body was evaluated by comparing the statistically processed data obtained before and after treatment, as well as in comparison with the indicators of animals of the control group. The analysis of hematological parameters of piglets during the experiment showed a decrease in the number of leukocytes in the animal’s blood after the use of drugs. The normalization of the leukogram was also noted by reducing the relative number of rod-nuclear neutrophils. In particular, this indicator decreased by 17.4% in group I piglets, and by 12% in group II piglets. It is noted that the clinical response to therapy was faster and more pronounced in animals, which used a non-steroidal anti-inflammatory drug in combination with an antimicrobial drug than in piglets, which were treated only by antibiotic. According to the results of biochemical studies, it was found that the content of urea in the serum of animals of both groups before the use of drugs exceeded more than 3 times the upper limit of physiological values for a given age group of piglets. After therapy with the drugs a significant decrease in the urea content in the blood serum of groups 1 and 2 animals was noted by 3.42 and 2.98 times, respectively. It is established that the activity of marker enzymes of the liver physiological state (ALT, AST) in the serum of group I piglets after complex treatment with the studied drugs was slightly reduced and was within the physiological values. In the serum of group II animals, which were treated only with antimicrobial drug, ALT activity increased by 12,0 %, and AST – by 38,6 %, compared to the initial data, and exceeded the limit of physiological values. An increase in the content of iron by 37.4 % in the blood of group I piglets, compared to the period before drug administration, was noted. No adverse reactions and negative phenomena were detected during the use of the test drug, and the drug was well tolerated. According to the clinical condition of the experimental group animals and the results of laboratory tests it was established that the use of non-steroidal anti-inflammatory drugs based on acetylsalicylic, ascorbic and citric acids simultaneously with antimicrobial therapy led to a faster improvement in the state of the musculoskeletal system. Observation during the month of the piglet’s clinical conditions confirmed the safety of the drug in the recommended dosage and method of administration in the combined treatment of inflammatory processes of the musculoskeletal system.

Thermodynamic and stoichiometric laws ruling the fates of growing systems

We delve into growing open chemical reaction systems (CRSs) characterized by autocatalytic reactions within a variable volume, which changes in response to these reactions. Understanding the thermodynamics of such systems is crucial for comprehending biological cells and constructing protocells because it sheds light on the physical conditions necessary for their self-replication. Building on our recent work, where we developed a thermodynamic theory for growing CRSs featuring basic autocatalytic motifs with regular stoichiometric matrices, we now expand this theory to include scenarios where the stoichiometric matrix has a nontrivial left kernel space. This extension introduces conservation laws, which limit the variations in chemical species due to reactions, thereby confining the system's possible states to those compatible with its initial conditions. By considering both thermodynamic and stoichiometric constraints, we clarify the environmental and initial conditions that dictate the CRSs' fate—whether they grow, shrink, or reach equilibrium. We also find that the conserved quantities significantly influence the equilibrium state achieved by a growing CRS. These results are derived independently of specific thermodynamic potentials or reaction kinetics, therefore underscoring the fundamental impact of conservation laws on the growth of the system. Published by the American Physical Society 2024

Periodic Behaviour of General Systems

A continuous function on the product of compact metric spaces to itself and back to the same space is known as a genera system. Where each element's orbit is an infinite sequence and where the first two elements are the same as given and next to it depends on the two elements prior to it form stronger conditions for the orbit. We could define an m-step dynamical system by extending the definition of a compact metric space to its m-times product. Because the system's current state frequently depends directly on the conditions of previous terms, this system appears more realistic. The basic theorems regarding periodic points and their related points, such as fixed point, limit points, recurrent points, will be proved in this paper. We also define the topological transitivity and its properties. In the end we find periodic points with periods one and two for affine maps and periodicity of tent map in dynamical system and generalised dynamical system.

NOSOCOMIAL ENDOCARDITIS ON AORTIC BIOPROSTHESIS, A CASE OF ACCELERATED ATHEROSCLEROSIS

Abstract Male, 79 years old, presented to the ED with chest pain and hemodynamically instability. Approximately one month prior, he underwent aortic bioprosthesis implantation for severe aortic stenosis. Pre–intervention coronary angiography revealed diffuse atheromatous plaques, none of which were stenotic. Additionally, the patient‘s medical history included paroxysmal atrial fibrillation on NOAC, hypertension and COPD. Upon admission: NIBP 80/50 mmHg, HR 150 bpm, and oxygen saturation was 85%. ECG showed atrial fibrillation with ST–segment elevation from V1 to V5. Arterial blood gas analysis revealed pH 7.25 and lactate 6 mmol/L. He received inotropic and vasopressor support, and prompt coronary angiography was performed, revealing 99% stenosis of the mid left anterior descending artery at the bifurcation with the diagonal branch, which was treated with angioplasty and coronary stent placement (Fig.1). Transthoracic echocardiography demonstrated the presence of the aortic bioprosthesis with diffusely thickened leaflets consistent with multiple vegetations. Transesophageal echocardiography confirmed a nosocomial infectious endocarditis, with mild–to–moderate stenosis, and evidence of peri–prosthetic echogenic material directed towards the left atrium, suggestive of abscess. The patient reported low–grade fever and asthenia in the weeks prior. The systemic and local inflammatory state of the endocarditis contributed to an accelerated atherosclerotic process, destabilizing the plaque and resulting in its rupture. Blood cultures identified multidrug–resistant Staphylococcus hemolyticus, for which specific antibiotic therapy was started. The patient and his family declined cardiac surgery due to high operative risk. Follow–up TEE, after approximately six weeks of intravenous antibiotic therapy, showed reduced vegetations on the bioprosthetic valve leaflets, with evolution of the previously noted large echolucent cavity, along with two similar peri–prosthetic lesions. These findings were confirmed on contrast–enhanced CT. The patient, achieving hemodynamic stability, was discharged home, continuing intravenous antibiotic therapy (OPAT protocol). At the one–month post–discharge follow–up, the patient was asymptomatic and hemodynamically stable. A repeat TEE showed normally mobile bioprosthetic valve leaflets without vegetations, and the previously noted large cavity with internal flow, consistent with cleansed abscess (Fig.2–3).