Parameter Disturbances Research Articles

Static Foot Disturbances and the Quality of Life of Older Person with Rheumatoid Arthritis.

Disturbed static foot function is one of the main causes of impaired quality of life, which may be related to the frailty syndrome of older adult patients with Rheumatoid Arthitis (RA). The aim of the study was to evaluate the relationship between parameters of static foot function disturbances and quality of life of older adult patients with RA. The study was performed among 102 patients with RA diagnosed according to the American College of Rheumatology (ACR) and EULAR 2010 criteria. Patients were divided into four subgroups depending on radiological evaluation according to the Steinbrocker classification. Plantoconturography examination was conducted using a podoscope with a 3D scanner and software for computer foot examination CQ ST2K. Quality of life of patients with RA was evaluated using the Arthritis Impact Measurement Scales-2 (AIMS-2). A statistically significant relationship between AIMS-2 and parameters of static foot function disturbances was observed. The study revealed correlations between parameters of disturbed static foot function and RA severity in comparison to disease duration. Our results indicate a relationship between static foot function disturbances and quality of life of patients with RA, not only in the area of physical activity, but also in the social an emotional domain. Study results indicate that plantoconturography and assessment of quality of life using AIMS-2 could be useful as a diagnostic and prognostic tool in RA.

Light trapping and manipulation of quasibound states in continuum Ge2Sb2Se4Te metasurfaces

Actively tunable nanodevices play an important role in modern photonics systems. Metasurfaces based on phase-change materials (PCMs) provide a new way for the realization of such devices. At present, the PCM is usually integrated with the resonant metasurfaces with low $Q$ factor or as a resonator to achieve the optical switches. Note that less work has focused on the switching characteristics of strong light trapping of in high-$Q$-factor metasurfaces. The main reason is that PCM has a significant intrinsic loss. Recently, the PCM ${\text{Ge}}_{2}{\text{Sb}}_{2}{\text{Se}}_{4}{\text{Te}}_{1}$ (GSST) with ultralow loss has been proved by in experiment ($k\ensuremath{\approx}0$), which makes it is possible to achieve the active metasurfaces with high $Q$ factor. Moreover, the symmetry-protected bound states in the continuum (BICs) provides an effective method to achieve the high-$Q$-factor metasurface. The perturbation that breaks the in-plane inversion symmetry of a structure can transform such a BIC mode into a leaky quasi-BIC with high $Q$ factor. In this work, the BIC and the light trapping characteristics of quasi-BIC in PCM GSST metasurfaces are studied numerically. Through moving the relative position of nanobars, the structure symmetry of the amorphous GSST metasurface is disturbed, which makes an ideal BIC convert to a quasi-BIC with high $Q$ factor. The average field-enhancement factor (EF) of quasi-BIC is evaluated, which is proportional to the $Q$ factor of resonance mode. Meanwhile, the effects of structure parameters, polarization angle and incident angle of light on EF are also discussed. In addition, by calculating the EF values under different disturbance parameters $d$ and crystallization degrees $m$. The switching characteristic of light trapping of quasi-BICs is discussed. It is worth noting that the asymmetric parameters can be precisely controlled in the process of the excitation of BICs in this way, which provides a way for the realization of ultrahigh $Q$ factors and makes it possible to strongly trap light and manipulate it dynamically. Our work provides a route for actively tunable and reconfigurable micro or nano optical devices.

Association between Ferritin and COVID-19 Mortality in 1310 Moroccan Patients

The clinical picture of SARS-CoV-2 infection is variable, ranging from moderate to severe and critical forms. Various studies have shown that disturbances in certain biochemical parameters are correlated with the severity of the disease. They can be used to predict the risk of complications, allowing early and appropriate care of these patients. The aim of our study is to evaluate the correlation between admission ferritin levels and mortality in COVID-19 patients. We used data from the records of patients with positive RT-PCR admitted to the Mohamed V Military Training Hospital in Rabat between april 2020 and december 2021. Demographic and biologic data were exctracted from DxLab LIS of Dedalus. 1.310 patients are included; the average age is 56 years and 72% of patients are male. The all-cause mortality of seriously ill hospitalized patients in the intensive care units are 23%. 73% of patients who died were over 60 years. The mean ferritinemia at admission was 2040 ng/ml for patients who died versus 521 ng/ml for the survivors (p <0.01). The AUC of the ROC curve for ferritin levels predicting all-cause mortality is 0.745. The threshold of 800 ng/ml allows a sensitivity of 72% and a specificity of 30%. Logistic regression analysis showed that ferritin levels above 800 ng/ml and age above 60 years are risk factors for mortality (p<0.01) independently of each other. At hospitalisation of COVID-19 patients, high ferritin levels would be correlated with a bad prognosis justifying an early and adapted care of these patients.

Synthesis of a Control System for a Waste Heat Boiler with Forced Circulation under Restrictions on Control Actions

As is often the case in practice, classical control theory does not fully provide sufficient tools for solving applied problems of a certain specific class. Such problems include automatic control of waste heat boilers where physical restrictions are imposed on controls, namely, they must belong to the class of non-negative functions with restrictions on amplitude and growth rate. In the theoretical part of this paper, within the framework of the block approach, methods for the synthesis of general linear systems with one-sided restrictions on control actions and state variables were developed. Then, the developed algorithms were applied to the waste heat boiler control system under conditions of incomplete measurements of state variables and the action of parametric and external uncontrolled disturbances. The effectiveness of the proposed algorithms was confirmed by numerical simulation.

Robust Deadbeat Predictive Current Regulation for Permanent Magnet Synchronous Linear Motor Drivers With Parallel Parameter Disturbance and Load Observer

This article proposed a robust deadbeat predictive current regulation (DPCR) algorithm for permanent magnet synchronous linear motors (PMSLMs) drive based on parallel parameter disturbance and load observer (PPDLOB). First, to increase the dynamic performance of current loop, a modified DPCR algorithm considering control delay is induced by using a discrete-time PMSLM model. Second, the PPDLOB consists of parameter disturbance observer (PDOB) and load disturbance observer (LDOB) is designed on the basis of a variable gain exponential sliding mode method. The PDOB is used to overcome parameter mismatch problem of the modified DPCR, whereas the LDOB is utilized to estimate the load thrust and the observation is fed forward to the current loop for compensating external disturbance. Finally, a series of comparative experiments are conducted and the results verify the feasibility and correctness of the proposed method.

Tunisian Horehound (Marrubium vulgare) Aqueous Extract Improves Treatment of Bleomycin-Induced Lung Fibrosis in Rat.

Pulmonary fibrosis (PF) remains one of the most serious pneumopathies whose diagnosis and physiopathogenesis are still poorly understood and no treatment has been shown to be effective. Recently, many studies have shown a renewed interest in plants thanks to their pharmacological potentials, like horehound, known, for its anti-inflammatory and antioxidant activities. The present study investigated the effects of the aqueous extract of horehound (Mae) on bleomycin (BLM)-induced PF in rats. Thirty rats were divided into three groups. The control group received no treatment, the BLM group received only intratracheally BLM (2 mg/kg), and the Mae group underwent administration of BLM+ Mae (2 mL/kg) daily for 20 days. Obtained results showed that Mae, rich in polyphenols, could significantly improve the damage caused by BLM by reducing the inflammatory index and the fibrosis score, bringing the lung structure of fibrotic rats close to that of control rats. As well, Mae obviously acted on the BLM inflammatory reaction, and the counting of bronchoalveolar lavage fluid (Balf) cells showed an increase in total cell number and a decrease in the infiltration of inflammatory cells in the bronchoalveolar space. In addition, the BLM instillation was accompanied by oxidative stress in the lung, liver, and kidney tissues, proven by an increase in lipid peroxidation, as well as through depletion of superoxide dismutase (SOD) and catalase (CAT). The Mae treatment reversed all disturbances of BLM-induced oxidative stress parameters promoting antioxidant and anti-inflammatory of the latter. These findings point to Mae as a promising candidate for the treatment of pulmonary fibrosis.

Peripheral Cytopenia and Its Associated Factors in Type 2 Diabetes Mellitus Patients, Northwest Ethiopia.

BackgroundHematological abnormalities are linked with diabetes mellitus (DM) and play a major role in diabetes-related micro- and macro-vascular complications. Therefore, this study aimed to investigate the magnitude of peripheral cytopenia and associated factors in type 2 diabetes (T2DM) patients.MethodsA cross-sectional study was conducted from March to May 2021 at the University of Gondar Comprehensive Specialized Hospital. A total of 357 T2DM participants were selected using a simple random sampling technique. A total of 3 mL of venous blood samples were collected using the vacutainer method for the complete blood count (CBC). A univariate and multivariate regression analysis were used to investigate the association between dependent and independent variables. P-value ˂0.05 was considered statistically significant.ResultsThe magnitude of cytopenia, bicytopenia, and pancytopenia were 21% (95% CI: 17.1, 25.53), 1.1% (95% CI: 0.44, 2.85), and 0.56% (95% CI: 0.01, 1.12), respectively. Furthermore, the magnitudes of anemia, leucopenia, and thrombocytopenia were 8.7% (95% CI: 6.18, 12.06), 10.9% (95% CI: 8.09, 14.59), and 5.3% (95% CI: 3.43, 8.16), respectively. Being male (AOR: 3.23; 95% CI: 1.43, 7.56), lack of exercise (AOR: 2.70; 95% CI: 1.137, 6.43), and never married (AOR: 3.90; 95% CI: 1.248, 12.18) were all associated with anemia.ConclusionThis study showed that T2DM causes disturbances in the hematological parameters and leads to a mild level of cytopenia. It is, therefore, suggested that hematological abnormalities, especially cytopenia, should be monitored and controlled on a regular basis in T2DM patients for better prognosis and quality of life.

To study the effects of various artificial feed on growth rate of Carassius carassius (Gold Fish)

Present work was done with keeping view of the key concept as evaluation of growth pattern by feed management in gold fish with reference to physico-chemical parameters. Firstly, fish fingerlings were bought from market shop namely fish and fun Bhopal Madhya Pradesh. Fingerlings were then installed in aquarium, thereafter we started feeding fishes with experimental feed. All the three fishes of gold fish were almost uniform in size and weight. The fishes show better growth in experimental feed formed of soybean, Rice bran, Egg shell, Curry leaves, Moringa leaves, and chicken liver etc. fishes also show positive growth in experimental feed. The feeding of fishes fluctuate from the disturbance of any physio-chemical parameters of water, especially Temperature, pH and dissolved oxygen.

Robust Trajectory-Tracking Control of a Rotorcraft Using Immersion-and-Invariance-Based Adaptive Backstepping Control

This paper investigates an adaptive backstepping control based on the immersion-and-invariance (I&I) method for a rotorcraft’s trajectory-tracking control problem. To effectively cope with both parametric uncertainties and external disturbances affecting all forces and moments of a rotorcraft, the I&I-based disturbance observer is designed and combined with an adaptive backstepping controller. During the design process, a simple form of the observer structure is suggested, and the performance of the observer is analyzed using a candidate Lyapunov function. Then, the closed-loop stability of the adaptive controller is analyzed for both time-invariant and time-varying disturbances. Additionally, the tuning function-based adaptive backstepping controller is designed and used to investigate the outperformance achievable with the proposed method. Finally, comparative simulation results using a high-fidelity rotorcraft math model is provided to show the effectiveness of the proposed strategy.

The Formation of Large-Scale Plasma Disturbances Upon HF Ionosphere Heating: Dependence of the Disturbance Parameters on the Frequency and Power of HF Radiation

The Formation of Large-Scale Plasma Disturbances Upon HF Ionosphere Heating: Dependence of the Disturbance Parameters on the Frequency and Power of HF Radiation

Epidemiological and biological profiles of chronic renal failed at the University Hospital of Joseph Ravoahangy Andrianavalona in Madagascar

Introduction: Chronic renal failed is an irreversible decline in renal function as measured by glomerular filtration rate. The aim of this study is to describe the epidemiological characteristics of chronic renal failed. Methods: This is a retrospective and descriptive study from January 1, 2019 to December 31, 2020 carried out at the UPFR (Paraclinical Unit of Training and Research) of Biochemistry and the USFR (Care Unit of Training and Research) of Nephrological intensive care of CHU-JRA (University hospital center Joseph Ravoahangy Andrianavalona). All biochemical analysis request forms prescribed by the nephrological intensive care department were included, with clinical information of chronic renal failure and confirmed GFR<60 ml/mn/1.73 m2 on the patient's file. Results: Fifty files were selected. The average age was 50.80 years, with a sex ratio of 1.5. The most affected population generally had a low standard of living. Hypertensive patients were the most common, accounting for 82% of cases, with diabetes in third place with 32% of cases. The mean creatinine level was 1067 µmol/l. The average glomerular filtration rate was 7.25. The uraemia was 44.20 mmol/l. Among the ionic disorders, hyperkalaemia was the most common, accounting for 68% of cases. Of the 78% (n=39) of patients who had a blood count, 92.31% (n=36) had normochromic normocytic anaemia. Conclusion: Chronic renal failed remains a public health problem especially in low income countries. It is always associated with other disturbances of biological parameters that should be monitored and corrected.

Effectiveness of Saffron against Hepatotoxicity Caused by Silver Nanoparticles in Vivo

Adverse effects of silver nanoparticles (Ag-NPs) on health remain a concern. This research study was performed to appreciate the activity of saffron plant (SAF) upon Ag-NPs-induced hepatotoxicity. Eighteen male rats were consumed, separated into three groups of equal numbers. The animals of the group (CON) were not dosed with either treatment, while the animals of the group (Ag-NPs) were treated with Ag-NPs orally. In the latter group (Ag-NPs + SAF) intoxicated rats with Ag-NPs were provided with SAF. The experiment lasted seven days. The study found that dosing with Ag-NPs led to a considerable elevates in serum levels of biochemical parameters of liver function and hepatic oxidative stress, while significantly diminished glutathione activity. But the combined use of SAF extract improved the disturbed hepatic parameters. It was concluded that SAF could efficaciously mitigate Ag-NPs-induced liver toxicity in vivo. More investigations are needed to determine the exact mechanisms behind affront’s ability to protect the liver. Keywords: Silver nanoparticles, biochemical parameters, hepatotoxicity.

Event-triggering load frequency control for multi-area power system based on random dynamic triggering mechanism and two-side closed functional

By taking into account sampled-data mechanism and transmission delay, the novel event-triggering load frequency control (LFC) strategy involving random dynamic triggering algorithm (RDTA) is developed for multi-area power systems in this paper. Firstly, an improved multi-area LFC model considering sampling and transmission delay (STD) simultaneously is addressed. Secondly, a modified event-triggering mechanism (ETM) with RDTA is proposed, considering parameter disturbances and a dynamic adjustment mechanism of the triggering threshold. Thirdly, a more advanced Lyapunov–Krasovskii functional (LKF) is constructed, introducing the delay-dependent matrices, more variable cross terms and the two-sided closed functional. Furthermore, two less conservative stability criteria are obtained according to the designed approach. Finally, two multi-area LFC systems are presented to verify the progressiveness of the proposed approach.

Analytical Solution of the Ray Equations of Hamilton for Rossby Waves on Stationary Shear Flows

The asymptotic behavior of Rossby waves in the ocean interacting with a shear stationary flow is considered. It is shown that there is a qualitative difference between the problems for the zonal and non-zonal background flow. Whereas only one critical layer arises for a zonal flow, then several critical layers can exist for a non-zonal flow. It is established that the integrated ray equations of Hamilton are equivalent to the asymptotic behavior of the Cauchy problem solution. Explicit analytical solutions are obtained for the tracks of Rossby waves as a function of time and initial parameters of the wave disturbance, as well as the magnitude of the shear and angle of inclination of the flow to the zonal direction. The ray equations of Hamilton are analytically integrated for Rossby waves on a shear flow. The obtained explicit expressions make it possible to calculate in real-time the Rossby wave tracks for any initial wave direction and any shear current inclination angle. It is shown qualitatively that these tracks for a non-zonal flow are strongly anisotropic.

L-NAC reverses of the adverse effects of fentanyl infusion on ventilation and blood-gas chemistry

There is an urgent need for development of drugs that are able to reverse the adverse effects of opioids on breathing and arterial blood-gas (ABG) chemistry while preserving opioid analgesia. The present study describes the effects of bolus injections of N-acetyl-L-cysteine (L-NAC, 500 μmol/kg, IV) on ventilatory parameters, ABG chemistry, Alveolar-arterial (A-a) gradient, sedation (righting reflex) and analgesia status (tail-flick latency assay) in unanesthetized adult male Sprague Dawley rats receiving a continuous infusion of fentanyl (1 μg/kg/min, IV). Fentanyl infusion elicited pronounced disturbances in (1) ventilatory parameters (e.g., decreases in frequency of breathing, tidal volume and minute ventilation), (2) ABG chemistry (decreases in pH, pO2, sO2 with increases in pCO2), (3) A-a gradient (increases that were consistent with reduced alveolar gas exchange), and (4) sedation and analgesia. Bolus injections of L-NAC given 60 and 90 min after start of fentanyl infusion elicited rapid and sustained reversal of the deleterious effects of fentanyl infusion on ventilatory parameters and ABG chemistry, whereas they did not affect the sedative or analgesic effects of fentanyl. Systemic L-NAC is approved for human use, and thus our findings raise the possibility that this biologically active thiol may be an effective compound to combat opioid-induced respiratory depression in human subjects.

Intelligent system of adaptation typical laws automatic regulation with the function of identification structure and parameters object

The structure of an intelligent system for adapting typical automatic control laws with the function of identifying the structure and parameters of an object has been developed and described. The developed system solves a complex of interrelated tasks: identification of the structure and parameters of an object, calculation and selection of the controller type, determination of parametric disturbances in a closed control loop. The intelligent system consists of three circuits: the identification circuit, the ACS design circuit, and the executive circuit. The tasks of the identification circuit include: identification of the structure and parameters of the object by observing the time characteristic of the object with a step action at the input; determination of the presence of a parametric disturbance by the method of comparative assessment of transient processes of the reference model and the real control object. According to the results of identifying the structure and parameters of the object, the controller is designed - the calculation of parameters and the choice of the type of controller. The executive circuit is represented by a closed control system. Neural networks were chosen as a tool for implementing the identification subsystem and the regulator design subsystem. As a prototype of the control object, typical dynamic links and their connections were chosen. The article contains: description of the structure of the intelligent system of adaptation of typical automatic control laws; description of subsystems for identifying and designing the regulator, structural and graphical diagrams, simulation results.

A Novel Fast Iterative Learning Control for Linear Discrete Systems with Parametric Disturbance and Measurement Noise

Precise industrial control technology is constantly in need of accurate and strong control. Error convergence for a typical linear system is very minimal when using a conventional iterative learning control strategy. This study develops a quick iterative learning control law to address this issue. We have presented a new PD iterative learning control approach which is basically grounded on backward error and control parameter rectification for a class of linear discrete time-invariant (LDTI) systems. We have deliberated the repetitive system, which has constraint disturbance and measurement noise. First, we have developed a form of the faster learning law along with a full explanation of the algorithm’s control factor generation process. And then, using the vector method in conjunction with the theory of spectral radius, sufficient conditions for the algorithm’s convergence are introduced for parameter estimation with no noise, parameter uncertainty but excluding the noise, parameter uncertainty with small perturbations, and noise in four different scenarios. Eventually, results show that convergence depends on the control law’s learning factor, the correction term, the factor of association, and the learning interval. Ultimately, the simulation results indicate that suggested approach has a faster error convergence as compared with classical PD algorithm.

Analysis dynamic characteristics brushless motor of the mechatronic system in conditions of parametric uncertaintyby computer simulation methods

THE PURPOSE. Currently, brushless motors – electric machines with permanent magnets on the rotor and a rotor position sensor controlled by a sinusoidal voltage from frequency converters, are widely used in mechatronic and robotic systems. The control algorithm is formed on the basis of information about the current values of the parameters brushless motor mechatronic system using a nominal or reference mathematical model, which is, as a rule, an idealized representation of a real device. The non-stationarity of the parameters object of study, as well as the possible uncertainty of its mathematical description due to the simplification of the mathematical model, lead to undesirable or unacceptable results when forming the control algorithm of the mechatronic system. The problem arises of analyzing the dynamic characteristics of a brushless motor under conditions of parametric uncertainty in order to determine the parameters that most affect the functioning of the mechatronic system and the phase coordinates that are sensitive to these changes.METHODS. When solving the problem, methods of the sensitivity theory are used to obtain the corresponding vector-matrix equations, the solution of which is carried out by means of the MatLab software environment.RESULTS. In this paper, sensitivity equations are obtained for the active resistance and projections of the stator winding inductance on the longitudinal and transverse coordinate axes, as well as for the moment of inertia of the brushless motor. A vector-matrix block diagram for calculating the sensitivity functions of a brushless motor is formed, the characteristic feature of which is the presence of a non-zero matrix of free terms, reduced to the input of the sensitivity model. The corresponding Simulink models were built to study the influence of the listed quasi-stationary parameters on the rotation speed and torque on the shaft of the object of study. An analysis of the statistical characteristics additional motion of the specified phase coordinates of the brushless motor has been carried out, and graphical dependencies and steady-state values of dispersions and relative estimates have been obtained.CONCLUSION. An analysis of the dynamic characteristics of a brushless motor under conditions of parametric uncertainty made it possible to determine that the rotation speed of the machine is the most sensitive to parametric disturbances. This coordinate is the most informative and is of maximum interest in the formation of an optimization algorithm for a mechatronic system. The decisive role in the formation of the additional movement of the output coordinates of the brushless motor is made by a change in the projection of the stator inductance on the transverse coordinate axis, which is an order of magnitude greater than the contribution to the additional movement of coordinates from other unstable parameters. It is expedient to use the results obtained in the course of the study when constructing an optimal control algorithm for a mechatronic system under conditions of parametric uncertainty.

Algorithm for parametric identification of the DC electric drive using the inverse model

THE PURPOSE. In modern control systems of various industrial units, the basis for the automation of technological processes is an electric drive. High requirements for the quality of the control process determine the formulation and solution of scientific and practical tasks for the development and creation of new promising control systems for electric drives (EDCS), allowing to maintain the required quality of functioning under the influence of destabilizing factors. These factors can affect the control system in the form of external disturbances and be summed up with the corresponding signals of the closed EDCS, and also be expressed in the form of parametric disturbances. The need arises to create such a control system that will allow for the identification of the parameters of the EDCS by introducing the appropriate identification algorithms into its structure.METHODS. When solving the problem, a search-free gradient method of adaptive identification was used, implemented by means of the MatLab software environment.RESULTS. The paper considers the problem of parametric identification of an electric drive with a DC motor based on the definition of sensitivity functions. Wherein to construct an algorithm for parametric identification, an inverse model of the studied EDCS is used, the quality indicator is the squared discrepancy, and the identifiable parameter is the overall transmission coefficient of the electric drive.CONCLUSION. Modeling in the MatLab software environment showed a high robustness of the developed identification algorithm to parametric disturbances that do not affect the steadystate value of the identified parameter. The proposed method for compensating the moment of resistance electric drive also made it possible to provide a low sensitivity algorithm to external disturbances. The identification of the overall transmission coefficient of a DC electric drive is carried out with an error not exceeding 0.5% in real time under the conditions of the influence of disturbances of various physical nature.

Analysis of Dietary Habits and Nutritional Status of Children with Down Syndrome in the Context of Lipid and Oxidative Stress Parameters.

Introduction: The risk of obesity in children with Down syndrome is high. Undoubtedly, proper nutrition plays an important role in the prevention of excess body weight and is associated with a reduction of metabolic complications. The aim of the study was to assess the problem of disturbances in the nutritional status and eating habits of children with DS. Methods: A total of 39 patients were included in the study. The nutritional status was assessed by anthropometric tests and Dual X-ray Absorptiometry. Eating habits were assessed using the Child Eating Behavior Questionnaire and the Food Frequency Questionnaire. Blood samples were taken to determine the oxidative stress and lipid parameters. Results: Obesity was recognized in 15% of subjects and 23% were overweight. Children that were overweight were characterized by higher levels of triglycerides, atherogenic index of plasma, and apoA2 and apoE levels. Fat mass, fat mass/height2 index, and visceral fat mass correlated with thiobarbituric acid reactive substances and advanced oxidative protein product level. The analysis of the Child Eating Behavior Questionnaire showed that children struggling with being overweight were more interested in food compared to those with normal body weight. A positive correlation was identified between waist circumference and food interest categories. Insufficient consumption of dairy products, vegetables, whole grain products, as well as fruits, seeds, nuts, and fatty fish was noted. Patients were less likely to consume products that are a good source of mono- and polyunsaturated fatty acids. Conclusions: In children with Down syndrome and obesity, disturbances in lipid and oxidative stress parameters are observed. Abnormal eating habits in all children with Down syndrome regardless of their nutritional status were noted. Proper nutritional education, nutritional control, and management of metabolic problems are essential in this group of patients.