Automated diagnosis of schizophrenia based on spatial-temporal residual graph convolutional network.

BACKGROUND: Schizophrenia (SZ), a psychiatric disorder for which there is no precise diagnosis, has had a serious impact on the quality of human life and social activities for many years. Therefore, an advanced approach for accurate treatment is required. NEW METHOD: In this study, we provide a classification approach for SZ patients based on a spatial-temporal residual graph convolutional neural network (STRGCN). The model primarily collects spatial frequency features and temporal frequency features by spatial graph convolution and single-channel temporal convolution, respectively, and blends them both for the classification learning, in contrast to traditional approaches that only evaluate temporal frequency information in EEG and disregard spatial frequency features across brain regions. RESULTS: We conducted extensive experiments on the publicly available dataset Zenodo and our own collected dataset. The classification accuracy of the two datasets on our proposed method reached 96.32% and 85.44%, respectively. In the experiment, the dataset using delta has the best classification performance in the sub-bands. COMPARISON WITH EXISTING METHODS: Other methods mainly rely on deep learning models dominated by convolutional neural networks and long and short time memory networks, lacking exploration of the functional connections between channels. In contrast, the present method can treat the EEG signal as a graph and integrate and analyze the temporal frequency and spatial frequency features in the EEG signal. CONCLUSION: We provide an approach to not only performs better than other classic machine learning and deep learning algorithms on the dataset we used in diagnosing schizophrenia, but also understand the effects of schizophrenia on brain network features.

Surrogate-Assisted Differential Evolution for the Design of Multimode Resonator Topology.

The microstrip devices based on multimode resonators represent a class of electromagnetic microwave devices, promising use in tropospheric communication, radar, and navigation systems. The design of wideband bandpass filters, diplexers, and multiplexers with required frequency-selective properties, i.e., bandpass filters, is a complex problem, as electrodynamic modeling is a time-consuming and computationally intensive process. Various planar microstrip resonator topologies can be developed, differing in their topology type, and the search for high-quality structures with unique frequency-selective properties is an important research direction. In this study, we propose an approach for performing an automated search for multimode resonators' conductor topology parameters using a combination of evolutionary computation approach and surrogate modeling. In particular, a variant of differential evolution optimizer is applied, and the model of the target function landscape is built using Gaussian processes. At every iteration of the algorithm, the model is used to search for new high-quality solutions. In addition, a general approach for target function formulation is presented and applied in the proposed approach. The experiments with two microwave filters have demonstrated that the proposed algorithm is capable of solving the problem of tuning two types of topologies, namely three-mode resonators and six-mode resonators, to the required parameters, and the application of surrogated-assisted algorithm has significantly improved overall performance.

Design of an In Vitro Semicircular Canal Model and Its Use for the Study of Canalithiasis.

Canalithiasis is a common vestibular system disorder, which may lead to a specific form of vertigo known as BPPV or top-shelf vertigo. In this paper, based on the actual geometric parameters of the human semicircular canal, we designed a four-fold in vitro one-dimensional semicircular canal model using technologies such as three-dimensional printing, image processing, and target tracking. We investigated the essential characteristics of the semicircular canal, such as the time constant of the cupula and the relationship between the number, density, and size of the canalith and the cupular deformation during canalith settlement. The results showed a linear relationship between the number and size of the canalith and the amount of cupular deformation. We also found that when the number of canaliths reached a particular scale, the interaction between the canaliths exerted an additional disturbance on the cupular deformation ("Z" twist). In addition, we explored the latency time of the cupula during canalith settlement. Finally, we verified that the canaliths had little effect on the frequency characteristics of the semicircular canal by a sinusoidal swing experiment. All the results validate the reliability of our 4-fold in vitro one-dimensional semicircular canal model.

Study of Force-Frequency Characteristics in AT-Cut Strip Quartz Crystal Resonators with Different Rotation Angles.

This paper investigated the force-frequency characteristics of AT-cut strip quartz crystal resonator (QCR) employing finite element analysis methods and experiments. We used the finite element analysis software COMSOL Multiphysics to calculate the stress distribution and particle displacement of the QCR. Moreover, we analyzed the impact of these opposing forces on the frequency shift and strains of the QCR. Meanwhile, the resonant frequency shifts, conductance, and quality factor (Q value) of three AT-cut strip QCRs with rotation angles of 30°, 40°, and 50° under different force-applying positions were tested experimentally. The results showed that the frequency shifts of the QCRs were proportional to the magnitude of the force. The highest force sensitivity was QCR with a rotation angle of 30°, followed by 40°, and 50° was the lowest. And the distance of the force-applying position from the X-axis also affected the frequency shift, conductance, and Q value of the QCR. The results of this paper are instructive for understanding the force-frequency characteristics of strip QCRs with different rotation angles.

The Automatic Design of Multimode Resonator Topology with Evolutionary Algorithms.

Microwave electromagnetic devices have been used for many applications in tropospheric communication, navigation, radar systems, and measurement. The development of the signal preprocessing units including frequency-selective devices (bandpass filters) determines the reliability and usability of such systems. In wireless sensor network nodes, filters with microstrip resonators are widely used to improve the out-of-band suppression and frequency selectivity. Filters based on multimode microstrip resonators have an order that determines their frequency-selective properties, which is a multiple of the number of resonators. That enables us to reduce the size of systems without deteriorating their selective properties. Various microstrip multimode resonator topologies can be used for both filters and microwave sensors, however, the quality criteria for them may differ. The development of every resonator topology is time consuming. We propose a technique for the automatic generation of the resonator topology with required frequency characteristics based on the use of evolutionary algorithms. The topology is encoded into a set of real valued parameters, which are varied to achieve the desired features. The differential evolution algorithm and the genetic algorithm with simulated binary crossover and polynomial mutation are applied to solve the formulated problem using the dynamic penalties method. The experimental results show that our technique enables us to find microstrip resonator topologies with desired amplitude-frequency characteristics automatically, and manufactured devices demonstrate characteristics very close to the results of the algorithm. The proposed algorithmic approach may be used for automatically exploring the new perspective topologies of resonators used in microwave filters, radar antennas or sensors, in accordance with the defined criteria and constraints.

[Amplitude-frequency characteristics of the retina under diffuse and pattern stimulation and new formalized signs of flicker and pattern electroretinogram]. / Amplitudno-chastotnye kharakteristiki setchatki pri diffuznoi i pattern-stimuliatsii i novye formalizovannye priznaki ritmicheskoi i pattern- élektroretinogramm.

The clinical sugnificance of electroretinogram interpretation depends heavily on the employed mathematical apparatus. Currently, conventional calculation of the amplitude and time parameters of electroretinogram (ERG) components and their relations (indices), as well as analysis of the frequency spectrum of the signal are becoming insufficient for interpretation of the obtained data. New approaches to diagnostics are currently being developed, using, among other things, expert systems, and neural network and simulation models. PURPOSE: To obtain additional formalized signs of ERG responses to flicker and pattern stimuli by analyzing the amplitude-frequency characteristics of the retina. MATERIAL AND METHODS: A photopic flicker ERG (FERG) and a transient pattern ERG (PERG) were recorded from healthy individuals and patients with glaucoma. Using the digitized FERG and PERG signals, the amplitude-frequency characteristics of the retina were studied. The results of diffuse and structured stimulation modeling in Matlab Simulink were used to identify the characteristics of retinal responses to rhythmic and pattern stimuli. RESULTS: The amplitude-frequency characteristics (AFC) of the retina were obtained for the first time. They objectively reflect its ability to convert spectra of stimulating signals into spectra of recorded ERG responses. Using the results of modeling, diffuse flicker and pattern stimuli we have identified features of retinal response in Matlab Simulink. Based on a simplified simulation model, a negative component (baseline drift) was detected in a healthy person's PERG and its effect on the results of retinal AFC evaluation was investigated. Polynomial approximation procedure of retinal AFC was performed for the first time allowing the use of coefficients of approximating polynomials as new formalized signs in diagnostics. CONCLUSION: AFC were shown to be an objective characteristic of retinal transfer properties, which depend on the type of stimuli acting on it, as well as on the etiology of the retinal disease.

Frequency Dependence of Receiving Sensitivity of Ultrasonic Transducers and Acoustic Emission Sensors.

Receiving displacement sensitivities (Rx) of ultrasonic transducers and acoustic emission (AE) sensors are evaluated using sinewave packet excitation method and compared to the corresponding data from pulse excitation method with a particular emphasis on low frequency behavior below 20 kHz, down to 10 Hz. Both methods rely on the determination of transmitter displacement characteristics using a laser interferometric method. Results obtained by two calibration methods are in good agreement, with average spectral differences below 1 dB, indicating that the two calibration methods yield identical receiving sensitivities. At low test frequencies, effects of attenuation increase substantially due to increasing sensor impedance and Rx requires correction in order to evaluate the inherent sensitivity of a sensor, or open-circuit sensitivity. This can differ by more than 20 dB from results that used common preamplifiers with ~10 kΩ input impedance, leading to apparent velocity response below 100 kHz for typical AE sensors. Damped broadband sensors and ultrasonic transducers exhibit inherent velocity response (Type 1) below their main resonance frequency. In sensors with under-damped resonance, a steep sensitivity decrease occurs showing frequency dependence of f²~f5 (Type 2), while mass-loaded sensors exhibit flat displacement response (Type 0). Such behaviors originate from sensor characteristics that can best be described by the damped harmonic oscillator model. This model accounts for the three typical behaviors. At low frequencies, typically below 1 kHz, receiving sensitivity exhibits another Type 0 behavior of frequency independent Rx. Seven of 12 sensors showed this flat region, while three more appear to approach the Type 0 region. This appears to originate from the quasi-static piezoelectric response of a sensing element. In using impulse method, a minimum pulse duration is necessary to obtain spectral fidelity at low frequencies and an approximate rule is given. Various factors for sensitivity improvement are also discussed.

Frequency characteristics of pressure transducer kits with inserted pressure-resistant extension tubes.

The accurate monitoring of arterial blood pressure is important for cardiovascular management. However, the frequency characteristics of pressure transducer kits are influenced by the length of the pressure-resistant tube. To date, there have been few studies addressing the frequency characteristics of pressure transducer kits with inserted pressure-resistant extension tubes (pressure-resistant extension tube (ET) circuits). In this study, we examine ET circuits from the viewpoint of the frequency characteristics of pressure transducer kits. DT4812J transducer kits (length 150 cm; Argon Medical Devices, TX, USA) were used. Three original ET circuits were prepared, with the pressure-resistant tube of the DT4812J being extended with a 30-cm length of pressure-resistant tube (180ET circuit), a 60-cm length of pressure-resistant tube (210ET circuit), and a 90-cm length of pressure-resistant tube (240ET circuit). Each of these circuits was evaluated as part of this study. The natural frequency of the original DT4812J circuit was 45.90 Hz while the damping coefficient was 0.160. For the 180 ET circuit, the natural frequency and damping coefficient were 36.4 Hz and 0.162, respectively. For the ET210 circuit, the natural frequency and damping coefficient were 30.3 Hz and 0.175, respectively. For the ET210 circuit, the natural frequency and damping coefficient were 25.3 Hz and 0.180, respectively. As a result of extending the circuit, it was found that the natural frequency decreased drastically, while the damping coefficient increased slightly. When the extension of a pressure transducer kit is required, we should pay careful attention to the major decrease in the natural frequency, which may influence the pressure monitoring.

[Clinical efficacy of the immunomodulatory agent cycloferon (tablets) in viral respiratory infections: Results of a systematic review and meta-analysis]. / Klinicheskaia éffektivnost' immunomoduliatora tsikloferona (tabletki) pri virusnykh infektsiiakh organov dykhaniia: rezul'taty sistematicheskogo obzora i metaanaliza.

The authors carried out a systematic review and subsequent meta-analysis of randomized clinical trials evaluating the efficacy of the immunomodulator agent cycloferon as tablets in adults and children with viral respiratory diseases. A total estimate of its clinical efficacy was obtained in terms of compared heterogeneous groups and response variables. The data published in 16 articles were used to calculate the formal parameters of the clinical efficacy of cycloferon (increased absolute and relative benefits, odds ratio (OR); the number of patients needed to be additionally treated with cycloferon to achieve a favorable outcome or to prevent a poor outcome in one patient, etc.). High heterogeneity hampered the unequivocal interpretation of results; however, combining the compared homogeneous groups in the meta-analysis (with adjustments for fixed and random effects) increased the statistical power of the investigation. In children aged 6 to 18 years, the OR for the positive effect of the drug (no new cases after its preventive administration) was 5.3 (95% confidence interval (CI), 4.8-5.9), heterogeneity test, χ2 = 249.5; p=0.000...; I2 = 94.8% (95% CI, 92.7-96.3%). This suggested the heterogeneity of clinical trial data and extrapolated this estimate to medical practice. The use of cycloferon in adults to treat acute respiratory viral infection enhanced their chances of enduring the disease in a mild form and avoiding serious complications: the OR for positive outcomes was 9.7 (95% CI, 7.0-13.0), while the effect was more homogeneous than in children (heterogeneity test, χ2 = 7.4; p=0.061...; I2 = 59.4% (95% CI, 0-86.5). Thus, the use of cycloferon to treat and prevent acute viral respiratory infections showed a more than 5-fold increase in the probability of avoiding the disease or enduring the latter in a mild form.

Effect of using a Planecta™ port with a three-way stopcock on the natural frequency of blood pressure transducer kits.

Blood pressure transducer kits are equipped with two types of Planecta™ ports-the flat-type Planecta™ port (FTP) and the Planecta™ port with a three-way stopcock (PTS). We reported that FTP application decreased the natural frequency of the kits. However, Planecta™ is an invaluable tool as it prevents infection, ensures technical simplicity, and excludes air. Hence, an ideal Planecta™ port that does not decrease the frequency characteristics is required. As a first step in this direction, we aimed to assess the influence of PTSs on the natural frequency of blood transducer kits. A DTXplus transducer kit (DT4812J; Argon Medical Devices, TX, USA) was used along with ≥1 PTSs (JMS, Hiroshima, Japan), and the frequency characteristics were assessed. The natural frequency and damping coefficient of each kit were obtained by using frequency characteristics analysis software, and these parameters were evaluated by plotting them on Gardner's chart. Regardless of whether one or two PTSs were inserted, the natural frequency of the kits only slightly decreased (from 42.5 to 41.1 Hz, when 2 PTSs were used). Thus, the frequency characteristics of the kits with PTSs were adequate for pressure monitoring. The insertion of ≥2 FTPs in pressure transducer kits should be avoided, as they markedly decrease the natural frequency and lead to underdamping. However, the effect of PTS insertion in pressure transducer kits on the frequency characteristics is minimal. Thus, we found that the use of PTS markedly improved the frequency characteristics as compared to the use of FTP.

Effect of planecta and ROSE™ on the frequency characteristics of blood pressure-transducer kits.

Pressure-transducer kits have frequency characteristics such as natural frequency and damping coefficient, which affect the monitoring accuracy. The aim of the present study was to investigate the effect of planecta ports and a damping device (ROSE™, Argon Medical Devices, TX, USA) on the frequency characteristics of pressure-transducer kits. The FloTrac sensor kit (Edwards Lifesciences, CA, USA) and the DTXplus transducer kit (Argon Medical Devices) were prepared with planecta ports, and their frequency characteristics were tested with or without ROSE™. The natural frequency and damping coefficient of each kit were obtained using frequency characteristics analysis software and evaluated by plotting them on the Gardner's chart. By inserting a planecta port, the natural frequency markedly decreased in both the FloTrac sensor kit (from 40 to 22 Hz) and the DTXplus transducer kit (from 35 to 22 Hz). In both kits with one planecta port, the damping coefficient markedly increased by insertion of ROSE™ from 0.2 to 0.5, optimising frequency characteristics. In both kits with two planecta ports, however, the natural frequency decreased from 22 to 12 Hz. The damping coefficient increased from 0.2 to 0.8 by insertion of ROSE™; however, optimisation was not achieved even by ROSE™ insertion. Planecta ports decrease the natural frequency of the kit. ROSE™ is useful to optimise the frequency characteristics in the kits without or with one planecta port. However, optimisation is difficult with two or more planecta ports, even with the ROSE™ device.

Mechanism of acoustic pressure spectrum shifting toward lower frequencies in applied current thermoacoustic imaging.

Objective. Thermoacoustic tomography (TAT) is a promising imaging technique used for early cancer diagnosis, tumor therapy, animal study and brain imaging. Although it is widely known that the TAT frequency response depends on the pulse width of the source and the size of the object, a thorough comprehension of the quantitative frequency modulation in TAT and the mechanism governing the shift in the thermoacoustic pressure spectrum towards lower frequencies with respect to the excitation source is still lacking. This study aims to understand why the acoustic pressure spectrum and the final voltage signals shift towards lower frequencies in TAT.Approach. We employed a linear time-invariant model. In the proposed model, the applied current thermoacoustic imaging (ACTAI) process is divided into the thermoacoustic stage and the acoustoelectric stage. These two stages are characterized by the thermoacoustic transfer function(TATF) and the transducer transfer function (TDTF), respectively. We confirmed the effectiveness of our model through a rigorous examination involving both simulations and experiments.Main results. Simulation results indicate that the TATF behaves as a low-pass filter. The inherent low-pass nature induces a shift towards low frequencies in the acoustic pressure spectrum. Experiments further confirm this behavior, demonstrating that the final electrical voltage also shifts towards low frequencies. Notably, employing the proposed model, there is a remarkable consistency between the main frequency bands of the synthesized and measured final voltage spectrum.Significance. The proposed model thoroughly explains how the TATF causes shifts to low frequencies in both the acoustic pressure spectrum and the final voltage spectrum in TAT. These insights deepen our understanding of optimizing TAT systems in the frequency domain, including aspects like filter design and transducer selection. Furthermore, we underscore the potential significance of this discovery for medical applications, particularly in the context of cancer diagnosis.

DC current-voltage and impedance spectroscopy characterization of nCdS/pZnTe HJ.

This paper describes the electrical and dielectric behavior of the nCdS/pZnTe HJ by current-voltage, capacitance-voltage characteristics, and impedance spectroscopy in a temperature interval 220-350 K. A microcrystalline p-ZnTe layer and n-CdS were grown on glass/ZnO substrate by closed space sublimation method. As frontal contact to CdS, the transparent ZnO and as a back contact to ZnTe, silver conductive paste (Ag) treated at 50 °C in vacuum were used. The current-voltage results of nCdS/pZnTe HJ show a rectifying behavior. The junction ideality factor, barrier height, and series resistance values were extracted from the rectifying curves at different temperatures. The built-in voltage, carrier concentration and depletion width were obtained from the capacitance-voltage measurements. Analysis of the J-V-T and C-V-T characteristics shows that the thermionic emission and recombination current flow mechanisms dominate in the nCdS/pZnTe HJ. The dielectric study reveals that the experimental values of the AC conductivity, dielectric constant, dielectric loss, the imaginary part of the electric modulus are found to be very sensitive to frequency and temperature. The dielectric constant and dielectric loss are observed to be high at the low frequency region. The increase in the values of electric modulus with the frequency implies an increase in the interfacial polarization at the interface of nCdS/pZnTe HJ. Jonscher's universal power law shows that with increasing frequency, AC conductivity increased. The results conductivity show that the ionic conductivity and interfacial polarization are the main parameters affecting the dielectric properties of the device when the temperature changes.

A new stress measurement strategy based on time-frequency characteristics of Lamb waves.

Existing stress evaluation methods based on the Lamb waves mainly use the time of flight (TOF) or velocity as the means of stress measurement. However, these two features used for stress measurement are sometimes insensitive to stress changes. Therefore, it is essential to explore other features that are potentially more sensitive to stress changes. The time-frequency spectrums of signals containing stress information have not yet been fully studied for stress evaluation. This paper proposes a uniaxial stress measurement method based on two time-frequency characteristics of Lamb waves, i.e., the slope of time-frequency spectrum distribution (TFSD) and pulse width impact factor. Theoretical expressions of the slope of TFSD are derived. The impacts of excitation signal parameters (i.e., bandwidth and center frequency) and noise on two time-frequency characteristics were discussed. Then, the fitting results of the finite element simulation are consistent with the results predicted by theory. To experimentally validate the proposed theory, aluminum plate specimens with two different types of adhesives were used for the experiment. According to the experimental stress measurement expression, three uniaxial tensile tests in the range of 35-95 MPa were conducted on the identical batch of specimens. The maximum standard deviation of multiple measured stress based on pulse width impact factor is 3.76433 MPa, demonstrating excellent measurement stability. The maximum standard deviation of multiple measured stress based on the slope of TFSD is 9.12492 MPa. It shows that the proposed methodology is a promising alternative for stress measurement.

On the Investigation of Frequency Characteristics of a Novel Inductive Debris Sensor.

Lubricants have the ability to reduce frictions, prevent wear, convey metal debris particles and increase the efficiency of heat transfer; therefore, they have been widely used in mechanical systems. To assess the safety and reliability of the machine under operational conditions, the development of inductive debris sensors for the online monitoring of debris particles in lubricants has received more attention from researchers. To achieve a high-precision, high-efficiency sensor for accurate prediction on the degree of wear, the equivalent circuit model of the sensor coil has been established, and its equations discovering the relationship between the induced voltage and excitation frequency have been derived. Furthermore, the influence of excitation frequencies and metal debris on the magnetic flux density has been analyzed throughout the simulations to determine the sensor magnetic field. In order to identify a frequency range suitable for detecting both ferrous and non-ferrous materials with a high level of sensitivity, the analytical analysis and experiments have been conducted to investigate the frequency characteristics of the developed inductive debris sensor prototype and its improved inspection capability. Moreover, the developed inductive debris sensor with the noticeable frequency characteristics has been assessed and its theoretical model has been also validated throughout experimental tests. Results have shown that the detection sensitivity of non-ferrous debris by the developed sensor increases with the excitation frequency in the range of 50 kHz to 250 kHz, while more complex results for the detection of ferrous debris have been observed. The detection sensitivity decreases as the excitation frequency increases from 50 kHz to 300 kHz, and then increases with the excitation frequency from 300 kHz to 370 kHz. This leads to the effective selection of the excitation frequency in the process of inspection. In summary, the investigation into the frequency characteristics of the proposed novel inductive debris sensor has enabled its broad applications and also provided a theoretical basis and valuable insights into the development of inductive debris sensors with improved detection sensitivity.

Electroencephalographic features of the developing brain in 72 dogs under xylazine sedation: a visual and statistical analysis.

Electroencephalogram (EEG) is a neurophysiological test, which is widely used in human medicine for epilepsy diagnosis and other neurological disorders. For an adequate interpretation, it is necessary to know the electroencephalogram features for different stages of development. Despite the growing interest in its implementation in veterinary medicine, standardized descriptions of the EEG features of the different stages of brain development in dogs are restricted to studies with limited number of dogs and limited age groups. In this research, the electroencephalographic recording of 72 dogs of different breeds and ages was carried out under xylazine sedation to determine tracing characteristics by visual analysis and through statistical analysis of power spectrum. To establish the EEG features of recordings, 3 essential aspects were selected: (a) the presence or absence of slow waves of 4 to 6-7 Hz; (b) the comparison of the electrical activity recorded in the temporal and dorsal cortex channels; and (c) the visual increase of the alpha activity. Visual analysis on both reference and bipolar montage was performed by the authors and additionally blindly corroborated by two human neurophysiologists. The results allowed us to differentiate 5 age groups: 0-5, 6-11, 12-17, 18-23, and >24 months. Statistical analysis of the power spectrum was performed by analysis of variance (ANOVA) with a completely randomized design (CRD) under factorial arrangement by observing the effect of ages, channels and electroencephalographic rhythms on relative power. The results obtained matched those observed in the visual analysis. According to our results, the characteristics of the EEG corresponding to the adult animal begin to appear at 12 months of age but stabilize after 24 months of age. In this case, the evident differences in the processes of development and maturation of the neopallium and the rhinencephalon play a determining role. Our results differ from those obtained by other authors, probably due to the addition of a deep electrode that facilitates the recording of temporal cortical activity and its deeper rhinencephalic connections.

Fabrication and DC-Bias Manipulation Frequency Characteristics of AlN-Based Piezoelectric Micromachined Ultrasonic Transducer.

Due to their excellent capabilities to generate and sense ultrasound signals in an efficient and well-controlled way at the microscale, piezoelectric micromechanical ultrasonic transducers (PMUTs) are being widely used in specific systems, such as medical imaging, biometric identification, and acoustic wireless communication systems. The ongoing demand for high-performance and adjustable PMUTs has inspired the idea of manipulating PMUTs by voltage. Here, PMUTs based on AlN thin films protected by a SiO2 layer of 200 nm were fabricated using a standard MEMS process with a resonant frequency of 505.94 kHz, a -6 dB bandwidth (BW) of 6.59 kHz, and an electromechanical coupling coefficient of 0.97%. A modification of 4.08 kHz for the resonant frequency and a bandwidth enlargement of 60.2% could be obtained when a DC bias voltage of -30 to 30 V was applied, corresponding to a maximum resonant frequency sensitivity of 83 Hz/V, which was attributed to the stress on the surface of the piezoelectric film induced by the external DC bias. These findings provide the possibility of receiving ultrasonic signals within a wider frequency range, which will play an important role in underwater three-dimensional imaging and nondestructive testing.

Study of hearing features of Congenital Malformation of the Middle and Outer Ear (CMMOE).

Background: There is no study on the hearing features of congenital malformation of middle and outer ears (CMMOE), including classification, grades, and frequency characteristics, which play a decisive role in the selection of precise hearing solutions for patients. Aims/Objectives: To analyze the hearing features of CMMOE and provide guidance for clinical practice.Material and Methods: 298 cases (351 ears) with CMMOE were retrospectively analyzed for the features of 0.5 ∼ 4KHz pure tone hearing, including the classification, grades and frequency characteristics. Results: We observed conductive deafness in 84.3% (296/351), mixed deafness in 15.7% (55/351), and 0% (0/351) sensorineural deafness. Grades measured by average Air Conduction Thresholds (ACT) of pure tone: Mild deafness (26-40dB HL) 0.6% (2/351), moderate deafness (41-55dB HL) 10.3% (36/351), moderate to severe deafness (56-70dB HL) 46.1%(162/351), severe deafness (71-90dB HL) 39.9%(140/351), extremely severe deafness (> 90 dB HL) 3.1%(11/351). The average ACT of 296 ears conductive deafness was 67 ± 10 dB HL, of which 56-80dB HL accounted for 78.1% (274/351). In 55 ears with mixed deafness, 32 ears (32/55 = 58.2%) increased Bone Conduction Threshold (BCT) at a single frequency, and out of 32 ears, 31ears (31/55 = 56.4%) ≤40dB HL, 25(25/32 = 78.1%) ears at 2KHz. In 55 ears with mixed deafness, 87.3% (48/55) increased BCT at 2KHz, and the average BCT was 35 ± 10dB HL. Conclusions and Significance: CMMOE result mainly in conductive deafness, moderate to severe and severe deafness. In mixed deafness, the BCT increased mainly at a single frequency, 2KHz and ≤40dB HL. These data suggest that bone-conductive hearing devices are a good solution for CMMOE hearing impairment.

Network analysis reveals a role of the hippocampus in absence seizures: The effects of a cannabinoid agonist.

The role of the hippocampus (Hp) in absence epileptic networks and the effect of endocannabinoid system on this network remain enigmatic. Here, using adapted nonlinear Granger causality, we compared the differences in network strength in four intervals (baseline or interictal, preictal, ictal and postictal) in two hours before (Epoch 1) and six hours (epochs 2, 3 and 4) after the administration of three different doses of the endocannabinoid agonist WIN55,212-2 (WIN) or solvent. Local field potentials were recorded for eight hours in 23 WAG/Rij rats in the Frontal (FC), Parietal PC), Occipital Cortex (OC) and in the hippocampus (Hp). The four intervals were visually marked by an expert neurophysiologist and the strength of couplings between electrode pairs were calculated in both directions. Ictally, a strong decrease in coupling strength was found between Hp and FC, as well as a large increase bidirectionally between PC and FC and unidirectionally from FC and PC to OC, and from FC to Hp over all epochs. The highest dose of WIN increased the couplings strength from FC to Hp and from OC to PC during 4 and 2 hr respectively in all intervals, and decreased the FC to PC coupling strength postictally in epoch 2. A single rat showed generalized convulsive seizures after the highest dose: this rat shared not only coupling changes with the other rats in the same condition, but showed many more. WIN reduced SWD number in epoch 2 and 3, their mean duration increased in epochs 3 and 4. Conclusions:during SWDs FC and PC are strongly coupled and drive OC, while at the same time the influence of Hp to FC is diminished. The first is in agreement with the cortical focus theory, the latter demonstrates an involvement of the hippocampus in SWD occurrence and that ictally the hippocampal control of the cortico-thalamo-cortical system is lost. WIN causes dramatic network changes which have major consequences for the decrease of SWDs, the occurrence of convulsive seizures, and the normal cortico-cortical and cortico-hippocampal interactions.

Simulation and experimental investigation of structural dynamic frequency characteristics control.

In general, mechanical equipment such as cars, airplanes, and machine tools all operate with constant frequency characteristics. These constant working characteristics should be controlled if the dynamic performance of the equipment demands improvement or the dynamic characteristics is intended to change with different working conditions. Active control is a stable and beneficial method for this, but current active control methods mainly focus on vibration control for reducing the vibration amplitudes in the time domain or frequency domain. In this paper, a new method of dynamic frequency characteristics active control (DFCAC) is presented for a flat plate, which can not only accomplish vibration control but also arbitrarily change the dynamic characteristics of the equipment. The proposed DFCAC algorithm is based on a neural network including two parts of the identification implement and the controller. The effectiveness of the DFCAC method is verified by several simulation and experiments, which provide desirable results.