Trajectory Planning and Subject-Specific Control of a Stroke Rehabilitation Robot using Deep Reinforcement Learning

There are approximately 13 million annual new stroke cases worldwide. Research has shown that robotics can provide practical and efficient solutions for expediting post-stroke patient recovery. Assistive robots provide automatic limb training, which saves a great deal of time and energy. In addition, they facilitate the use of data acquisition devices. The data is beneficial in terms of quantitative evaluation of the patient progress. This research focused on the trajectory planning and subject-specific control of an upper-extremity post-stroke rehabilitation robot. To find the optimal rehabilitation practice, the manipulation trajectory was designed by an optimization-based planner. A linear quadratic regulator (LQR) controller was then applied to stabilize the trajectory. The integrated planner-controller framework was tested in simulation. To validate the simulation results, hardware implementation was conducted, which provided good agreement with simulation. One of the challenges of rehabilitation robotics is the choice of the low-level controller. To find the best candidate for our specific setup, five controllers were evaluated in simulation for circular trajectory tracking. In particular, we compared the performance of LQR, sliding mode control (SMC), and nonlinear model predictive control (NMPC) to conventional proportional integral derivative (PID) and computed-torque PID controllers. The real-time assessment of the mentioned controllers was done by implementing them on the physical hardware for point stabilization and circular trajectory tracking scenarios. Our comparative study confirmed the need for advanced low-level controllers for better performance. Due to complex online optimization of the NMPC and the incorporated delay in the method of implementation, performance degradation was observed with NMPC compared to other advanced controllers. The evaluation showed that SMC and LQR were the two best candidates for the robot. To remove the need for extensive manual controller tuning, a deep reinforcement learning (DRL) tuner framework was designed in MATLAB to provide the optimal weights for the controllers; it permitted the online tuning of the weights, which enabled the subject-specific controller weight adjustment. This tuner was tested in simulation by adding a random noise to the input at each iteration, to simulate the subject. Compared to fixed manually tuned weights, the DRL-tuned controller presented lower position-error. In addition, an easy to implement high-level force controller algorithm was designed by incorporating the subject force data. The resulting hybrid position/force controller was tested with a healthy subject in the loop. The controller was able to provide assist as needed when the subject increased the position-error. Future research might consider model reduction methods for expediting the NMPC optimization, application of the DRL on other controllers and for optimization parameter adjustment, testing other high-level controllers like admittance control, and testing the final controllers with post-stroke patients

Stability Analysis of Behesht-Abad Water Conveyance Tunnel Inlet Portal Using Experimental, Limit Equilibrium and Numerical Methods

The Behesht-abad Water Conveyance Tunnel is one of the most important tunnels conveying water to central Iran plain having 60 km length and 6 m diameter. The tunnel portal intersects with important faults of the region which is nearby Ardal city. Therefore, the rock mass surrounding the tunnel portal faces instability problem. Initially, the joints characteristics of the rock mass surrounding the inlet portal were evaluated to find the dominant joint sets along with the characteristics required for stability analyses inputs. Also the deformation modulus and other engineering properties of the rock mass were assessed using the available drilled boreholes data. The extensive stability analyses were conducted using stereographic, empirical SMR, limit state equilibrium and 3-dimensional discontinuum numerical methods. Finally, the results of the analyses were compared together

Rare presentation of pancreatic schwannoma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Schwannoma is a rare tumor among pancreatic neoplasms. Schwannomas vary in size, and most of them are cystic, mimicking pancreatic cystic lesions. Generally, a definitive diagnosis is made at the time of histological analysis. The mainstay treatment is surgical resection.</p> <p>Case presentation</p> <p>We report an unusual presentation of pancreatic schwannoma with abdominal pain and several episodes of cholangitis in a 54-year-old Caucasian (Iranian) man. The condition was not diagnosed pre-operatively and Whipple's procedure was performed.</p> <p>Conclusion</p> <p>Pancreatic schwannoma is an important clinical entity to include in the differential diagnosis of pancreatic lesions. Pre-operative diagnosis is difficult but computed tomographic findings may be helpful. The tumor may also have atypical and rare presentations, such as cholangitis and weight loss. For benign tumors, simple enucleation is usually adequate, whereas malignant tumors require standard oncological resection.</p

Comparison of Methoxyisobutylisonitrile Scintigraphy and Ultrasonography in Preoperative Localization of Secondary Hyperparathyroidism

Background: In patients with secondary hyperparathyroidism, the four glands are not uniformly enlarged; therefore, preoperative localization is difficult in comparison with primary hyperparathyroidism. The aim of&nbsp;this study was to compare the usefulness of 99mTc-sestamibi scintigraphy versus ultrasonography in the preoperative assessment of patients with secondary hyperparathyroidism.Methods: Between October 2008 and March 2012, 25 uremic patients with secondary hyperparathyroidism underwent 99mTc-sestamibi scintigraphy and high resolution ultrasonography before total or subtotal parathyroidectomy. We measured plasma concentration of intact parathyroid hormone (PTH), calcium, phosphorus, and alkaline phosphatase (ALP) before parathyroidectomy.Results: Sensitivity and positive predictive value (PPV), respectively, were 47.3% and 97.8% for MIBI scintigraphy, and 69.5% and 96.9% for ultrasonography. The sensitivity of combined techniques was 84.2%.&nbsp;There was a positive correlation between the parathyroid glands’ weight and serum calcium level, and positive MIBI scintigraphy and ultrasonography results. However, there was no correlation between the preoperative serum PTH, phosphorus, alkaline phosphatase (ALP), dialysis duration, and parathyroid glands’ weight.Conclusions: Ultrasonography is a reliable non-invasive localization tool. It has greater sensitivity in localizing parathyroid glands in secondary hyperparathyroidism than scintigraphy

Electric Field Induced Alignment of Carbon Nanotubes: Methodology and Outcomes

In the current chapter, achievement of aligned carbon nanotube (CNT) network within the matrix via various kinds of electric fields (AC and DC) was evaluated. In this case, alignment mechanism of CNTs within the matrix and two useful techniques for justification of CNT alignment throughout the matrix were examined and presented, respectively. Afterward, effective factors in matter of CNT alignment and applicable procedures for fabrication of nanocomposites containing aligned CNTs were studied and presented, respectively. At the end, significant effects of CNT alignment on overall properties of nanocomposites that include electrical and mechanical properties were evaluated. Achieved results revealed that alignment of CNTs within the matrix can lead to significant improvement in the electrical and mechanical properties of nanocomposites at the same filler loading compared with randomly distribution of CNTs within the matrix, while production steps and conditions can also highly affect the outcome data

The prevalence of depression, anxiety, and stress in patients with breast cancer in Southeast Iran in 2019: a cross-sectional study

Introduction. Today, breast cancer patients suffer from various psychological symptoms that impose irreversible effects on their quality of life. The aim of the present study was to determine the prevalence of depression, anxiety, and stress in patients with breast cancer. Material and methods. This descriptive study was performed on 190 women with breast cancer from January 1, 2019 to July 30, 2019. Data collection was carried out using a convenience sampling method. The Standard Depression, Anxiety, and Stress Scale (DASS-21) was used to assess depression, anxiety, and stress. Results. The mean age of the patients was 46.3 years. Results showed the prevalence of depression, anxiety, and stress to be 28.4%, 43.2%, and 14.7%, respectively. Conclusion. The results indicate that it is vital to measure the level of depression and anxiety in women withbreast cancer, which are two common mental disorders in breast cancer

Frequency Domain Electroretinography in Retinitis Pigmentosa versus Normal Eyes

Purpose: To compare electroretinogram (ERG) characteristics in patients with retinitis pigmentosa (RP) and normal subjects using frequency domain analysis. Methods: Five basic ERG recordings were performed in normal subjects and patients with a clinical diagnosis of RP according to the ISCEV (International Society of Clinical Electrophysiology of Vision) protocol. Frequency domain analysis was performed by MATLAB software. Different frequency domain parameters were compared between the study groups. Results: Peak frequency (Fmod) of flicker and oscillatory responses in RP patients showed significant (P<0.0001) high pass response as compared to normal controls. Peak frequency (Fmod) of the other responses was not significantly different between the two groups. Conclusion: In addition to conventional ERG using time domain methods, frequency domain analysis may be useful for diagnosis of RP. Oscillatory and flicker responses may be analyzed in frequency domain. Fast Fourier transform may reveal two distinct high pass responses (shift to higher frequencies) in Fmod. Time and frequency domain analyses may be performed simultaneously with many modern ERG machines and may therefore be recommended in RP patients

Asociación de los polimorfismos P561T y C422F del gen receptor de la hormona del crecimiento con dimensiones faciales.

Background: Growth hormone plays a significant role in determining craniofacial morphology. Mutations of its receptor gene might be associated with mandibular prognathism (MP). Purpose: The aim of the current study was to evaluate growth hormone receptor (GHR) gene polymorphisms in relation to facial dimensions. Material and Method: The study enrolled 65 participants with class III profile in MP group and 60 orthognathic control participants. Genomic DNA was extracted from a blood sample from the patients and the P561T and C422F polymorphisms of GHR gene were screened by PCR-RFLP method followed by Sanger sequencing of randomly selected samples to validate the genotyping results. Chi square was used to compare distribution of polymorphism in MP and control groups (p&lt;0.05). Results: Heterozygous P561T mutation was found in 10.77% and 8.33% of MP and control groups, respectively (p=0.644) while none of the subjects had the C422F mutation. Sanger sequencing confirmed the genotyping results from the PCR-RFLP method. P561T polymorphism was significantly associated with ramus and lower facial height in MP patients and with ramus height in orthognathic patients (p&lt;0.05). Conclusion: The results indicate that the P561T polymorphism of the GHR gene is associated with the vertical dimension of the mandible in an Iranian population.Antecedentes: La hormona del crecimiento desempeña un papel importante en la determinación de la morfología craneofacial. Las mutaciones de su gen receptor podrían estar asociadas con el prognatismo mandibular (PM). Propósito: El objetivo del presente estudio fue evaluar dos polimorfismos del gen del receptor de la hormona del crecimiento (RHC) en relación con las dimensiones faciales. Materiales y Métodos: El estudio incluyó a 65 participantes con perfil de clase III en el grupo MP y 60 participantes de control ortognático. El ADN genómico se extrajo de una muestra de sangre de los pacientes y los polimorfismos P561T y C422F del gen RHC se seleccionaron mediante el método PCR-RFLP seguido de la secuenciación por Sanger de muestras seleccionadas al azar para validar los resultados del genotipo por RFLP. El test chi cuadrado se utilizó para comparar la distribución del polimorfismo en el grupo MP y grupo control (p&lt;0.05).Resultados: Se encontró mutación heterocigota P561T en 10.77% y 8.33% de los grupos PM y control, respectivamente (p=0.644) mientras que ninguno de los sujetos tenía la mutación C422F. La secuenciación de Sanger confirmó los resultados de genotipado por el método PCR-RFLP. El polimorfismo P561T se asoció significativamente con la rama y la altura facial más baja en pacientes con PM y con la altura de la rama en pacientes ortognáticos (p&lt;0.05). Conclusión: Los resultados indican que el polimorfismo P561T del gen RHC está asociado con la dimensión vertical de la mandíbula en una población iraní

A new approach to design switching strategy for the buck converters

In this paper, a novel method is developed to control switched DC-DC Buck converters. The circuit dynamic is described as an affine linear switched system. Utilizing switched systems theory, a switching state-feedback law is derived to asymptotically stabilize the desired equilibrium point and also minimize a guaranteed cost. The efficiency of the proposed method is illustrated by simulation which verifies the improvement of the obtained results compared with the literatures