Assessment of a practical technique for active control of sound using microphone and speaker

AbstractIn this analytical study, it has been desired to develop a practical and simple control mechanism to control, at a given point and its neighborhood, the sound arriving from a distant source, assuming that a primary pure-tone sound pressure is propagated from a relatively far distance. The control model consists of a microphone as a sensor for measuring the sound pressure and a loud speaker for applying the control force. Corresponding equations have been developed to determine an optimum control force, and afterwards a parametric study on the factors affecting the control results has been performed. The results show that the control system can significantly reduce low frequency sound pressure in the region near the target point. The results also demonstrate less effectiveness in controlling high frequency sound pressures. Moreover, the larger the distance of the loudspeaker to the given controlled point is, the wider the controlled area will be. Also, it was found that though the distance between the sensor and the actuator does not have any effect on the size of the area which can be controlled, such distance is of greatest importance in that the available time to control increases directly by increasing the distance

Designing optimal controllers for nonlinear frames by considering the effect of response feedback

AbstractThe effect of response feedback on designing optimal controllers for nonlinear frames has been studied. Different combinations of response feedback have been used in the performance index. The Newmark based nonlinear instantaneous optimal control algorithm has been used as the control algorithm in controlling the response of an eight-story bilinear hysteretic frame subjected to white noise excitation and real earthquakes, and controlled by either eight actuators or a single actuator. While the objective has been to minimize the maximum control force for reducing the maximum drift to below the yielding level, the distributed genetic algorithm (DGA) has been used to determine the proper set of weighting matrices in the performance index. Results show that the performance of the active control system depends on the combination of response feedback, where the velocity feedback has been more effective than acceleration and displacement. Also, although using the full feedback of response in the performance index leads to the design of optimal controllers that require the smallest control force, it is costlier, because it requires more online measurements. Finally, it has been concluded that amongst all possibilities, using only velocity feedback can provide the best results regarding the maximum required control force and online measurement, simultaneously

Time course of changes in passive avoidance and Y-maze performance in male diabetic rats

Diabetes mellitus is accompanied with disturbances in learning, memory, and cognitive skills in the human society and experimental animals. Therefore, this research study was conducted to evaluate time-dependent changes in passive avoidance and Y-maze performance in male diabetic rats. For this purpose, male Wistar rats were randomly divided into control and diabetic groups. For induction of diabetes, streptozotocin (STZ) was injected i.p. at a single dose of 60 mg/kg. For evaluation of learning and memory, initial latency (IL) and step-through latency (STL) were determined at the end of 1st, 2nd, and 3rd months using passive avoidance and Y-maze tasks. It was found out that mean IL exhibits a significant increase only at the end of 2nd (p<0.05) and 3rd (p<0.01) months. In addition, STL significantly reduced at the end of 2nd (p<0.05) and 3rd months (p<0.01). Regarding Y-maze task, alternation score of the diabetic rats was lower than that of the control ones at the end of 1st (p<0.05), 2nd (p<0.01), and 3rd (p<0.01) months as compared to time-matched control group. To conclude, at least one month is strictly required for development of behavioral disturbances in passive avoidance and Y-maze tasks in STZ-diabetic rats

The beneficial effect of (-)-epigallocatechin-3-gallate in an experimental model of Alzheimer's disease in rat: A behavioral analysis

Background: Progressive cognitive decline is one of the hallmark symptoms of Alzheimer's disease (AD) which can be modeled by β-amyloid injection into specific regions of brain. Since epigallocatechin-3-gallate (EGCG) is a potent antioxidant agent which its role against oxidative stress and inflammation has been shown in prior studies, we tried to determine whether EGCG administration protects against β-amyloid-induced memory and coordination impairment in rats. Methods: Animals (male Wistar rats) were divided into four groups: sham operated, EGCG-pretreated sham operated (sham + EGCG), untreated lesion (lesion), and EGCG-pretreated lesion (lesion + EGCG). Animals in lesion, lesion + EGCG, and sham + EGCG groups received sterile saline or saline plus EGCG (10 mg/kg) intraperitoneally one day pre-surgery and every other day for three weeks. The lesion was induced one day after EGCG pretreatment by injection of 4 μl of sterile saline or water containing 2 nmol/μl β-amyloid (1-40) into the hippocampal fissure. For behavioral analysis, psychomotor coordination (PMC) index and spontaneous alternation behavior were assessed using Rota-rod Treadmill and Y-maze, respectively at the third week post-lesion. Results: We found that β-amyloid (1-40) injection into hippocampus can decrease these behavioral indexes in lesion group in comparison with sham group which is similar to behavioral changes in AD. On the other hand, pretreatment with EGCG can improve the PMC index and spatial Y-maze alternation in the lesion + EGCG group in comparison with lesion group. Conclusion: We concluded that EGCG can be effective in restoring β-amyloid-induced behavioral derangements in rats regarding coordination and memory abilities

Transplantation of olfactory mucosa improve functional recovery and axonal regeneration following sciatic nerve repair in rats

Background: Olfactory ensheathing glia (OEG) has been shown to have a neuroprotective effect after being transplanted in rats with spinal cord injury. This study was conducted to determine the possible beneficial results of olfactory mucosa transplantation (OMT) which is a source of OEG on functional recovery and axonal regeneration after transection of the sciatic nerve. Methods: In this study, 36 adult female Sprague-Dawley rats were used. The sciatic nerve was transected in 24 rats and immediately repaired by sciatic-sciatic anastomosis, and randomly divided equally into two groups. The experimental group received the OMT at the transected site and the control group received the respiratory mucosa transplant. In another twelve rats as sham-operated animals, the sciatic nerve was exposed but no transection was made. DiI retrograde tracing was injected in the gastrocnemius muscle two months after surgery to allow visualization of the extent of axonal regeneration. Functional recovery was also assessed at 15, 30, 45 and 60 days after surgery using walking track analysis and sciatic function index (SFI) calculations. Results: The total number of DiI labeled motorneurones in the ventral horn (L4-L6) and the SFI scores were significantly higher in the group of rats that received olfactory mucosa rather than respiratory mucosa. Conclusions: The outcome indicates that olfactory mucosa is a useful treatment to improve nerve regeneration in mammals with peripheral nerve injury

Blockade of p75 neurotrophin receptor reverses irritability and anxiety-related behaviors in a rat model of status epilepticus

Background: Many recent epidemiological studies have shown that epileptic patients are more likely suffer from depression, anxiety, and irritability. However, the cellular mechanisms of epilepsy-induced psychotic behaviors are not fully elucidated. Neurotrophin receptors have been suggested to be involved in epilepsy and also in psychiatric disorders. Up-regulation of p75NTR expression and activation of p75NTR signalling cascades after the seizure have been shown, but the role of the p75 receptor in epilepsy-induced psychotic behaviors has not been documented so far. Therefore, the present work aimed to investigate the effect of p75 receptor blockade on seizure activity, irritability, and anxiety-like behaviors in a rat model of status epilepticus. Methods: Rats were injected with pilocarpine (350 mg/ kg, i.p.) to induce status epilepticus. Then various behavioral tests were performed after the blockade of p75NTR alone or in combination with p75 antagonist and phenobarbital. Molecular analysis by PCR was performed to investigate the expression of p75 and pro-NGF. Results: Molecular findings indicated a high level of mRNA expression for both p75 receptors and pro-NGF in the epileptic model group. Results also showed that the administration of p75 antagonist alone or in combination with phenobarbital was able to significantly influence the behavioral responses. Furthermore, 20-hours video monitoring showed a decrease in the frequency and duration of seizures in the rat group receiving p75 antagonist. Conclusion: Taken together, the present study suggests that the blockade of the p75 receptor may affect the irritability and anxiety-related behavior in a rat model of status epilepticus. © 2018, Pasteur Institute of Iran. All rights reserved

Dendritic spine changes in medial prefrontal cortex of male diabetic rats using golgi-impregnation method

Background: Neuropathy is one of the major complications contributing to morbidity in patients with diabetes mellitus. The effect of diabetes on brain has not. been studied so much and no gross abnormality has been found in the central nervous system of patients with diabetic neuropathy. This study was conducted to evaluate the time-dependent structural changes in medial prefrontal cortex of male diabetic rats using Golgi-impregnation method. Methods: Male Wistar rats were randomly divided into the control and diabetic groups. For induction of diabetes, a single dose of streptozotocin (60 mg/kg) was injected intraperitoneally. At the end of the first and second months, the rats were transcardially perfused with a solution of phosphate buffer containing paraformaldehyde and Golgi-imprognated method was used to evaluate the changes of dendritic spines in medial prefrontal cortex. Results: There was a significant reduction in the mean density of pyramidal neuron dendritic spines in the layers II and III of medial prefrontal cortex only after 2 months in the diabetic group compared to age-matched controls (P < 0.05). Conclusion: Diabetes induces a reduction in the spine density of apical dendrites of medial prefrontal cortex only in two-month diabetic rats

Blockade of p75 neurotrophin receptor reverses irritability and anxiety-related behaviors in a rat model of status epilepticus

Background: Many recent epidemiological studies have shown that epileptic patients are more likely suffer from depression, anxiety, and irritability. However, the cellular mechanisms of epilepsy-induced psychotic behaviors are not fully elucidated. Neurotrophin receptors have been suggested to be involved in epilepsy and also in psychiatric disorders. Up-regulation of p75NTR expression and activation of p75NTR signalling cascades after the seizure have been shown, but the role of the p75 receptor in epilepsy-induced psychotic behaviors has not been documented so far. Therefore, the present work aimed to investigate the effect of p75 receptor blockade on seizure activity, irritability, and anxiety-like behaviors in a rat model of status epilepticus. Methods: Rats were injected with pilocarpine (350 mg/ kg, i.p.) to induce status epilepticus. Then various behavioral tests were performed after the blockade of p75NTR alone or in combination with p75 antagonist and phenobarbital. Molecular analysis by PCR was performed to investigate the expression of p75 and pro-NGF. Results: Molecular findings indicated a high level of mRNA expression for both p75 receptors and pro-NGF in the epileptic model group. Results also showed that the administration of p75 antagonist alone or in combination with phenobarbital was able to significantly influence the behavioral responses. Furthermore, 20-hours video monitoring showed a decrease in the frequency and duration of seizures in the rat group receiving p75 antagonist. Conclusion: Taken together, the present study suggests that the blockade of the p75 receptor may affect the irritability and anxiety-related behavior in a rat model of status epilepticus. © 2018, Pasteur Institute of Iran. All rights reserved

Ruptured mitral valve aneurysm: A devastating complication of aortic valve endocarditis

Mitral valve aneurysm is a rare clinical entity that is mostly resulted from infective endocarditis, in particular, aortic valve endocarditis. Once mitral valve aneurysm ruptures and severe mitral regurgitation and hemodynamic instability develop, prompt surgery should be considered. Here we report a patient with ruptured mitral valve aneurysm associated with native aortic valve endocarditis that was improved after a successful mitral and aortic valve replacement surgery associated with antibiotic therapy for 6 weeks. © 2018 Wiley Periodicals, Inc

Ruptured mitral valve aneurysm: A devastating complication of aortic valve endocarditis

Mitral valve aneurysm is a rare clinical entity that is mostly resulted from infective endocarditis, in particular, aortic valve endocarditis. Once mitral valve aneurysm ruptures and severe mitral regurgitation and hemodynamic instability develop, prompt surgery should be considered. Here we report a patient with ruptured mitral valve aneurysm associated with native aortic valve endocarditis that was improved after a successful mitral and aortic valve replacement surgery associated with antibiotic therapy for 6 weeks. © 2018 Wiley Periodicals, Inc