3D hippocampal segmentation based on spatial and frequency domain features adaptive fusion and inter⁃class boundary region enhancement / 解剖学报

Objective Hippocampal atrophy is a clinically important marker for the diagnosis of many psychiatric disorders such as Alzheimer’s disease‚ so accurate segmentation of the hippocampus is an important scientific issue. With the development of deep learning‚ a large number of advanced automatic segmentation method have been proposed. However‚ 3D hippocampal segmentation is still challenging due to the effects of various noises in MRI and unclear boundaries between various classes of the hippocampus. Therefore‚ the aim of this paper is to propose new method to segment the hippocampal head‚ body‚ and tail more accurately. Methods To overcome these challenges‚ this paper proposed two strategies. One was the spatial and frequency domain features adaptive fusion strategy‚ which reduced the influence of noise on feature extraction by automatically selecting the appropriate frequency combination through fast Fourier transform and convolution. The other was an inter-class boundary region enhancement strategy‚ which allowed the network to focus on learning the boundary regions by weighting the loss function of the boundary regions between each class to achieve the goal of pinpointing the boundaries and regulating the size of the hippocampal head‚ body and tail. Results Experiments performed on a 50-case teenager brain MRI dataset show that our method achieves state-of-the-art hippocampal segmentation. Hippocampal head‚ body and tail had been improved compared to the existing method. Ablation experiments demonstrated the effectiveness of our two proposed strategies‚ and we also validated that the network had a strong generalization ability on a 260-case Task04_Hippocampus dataset. It was shown that the method proposed in this paper could be used in more hippocampal segmentation scenarios. Conclusion The method proposed in this paper can help clinicians to observe hippocampal atrophy more clearly and accomplish more accurate diagnosis and follow-up of the condition.

Study of heart rate variability to assess autonomic dysfunction in patients with chronic obstructive pulmonary disease of a tertiary care hospital of West Bengal: A cross-sectional comparative study

Background: Chronic obstructive pulmonary disease (COPD) is one of the major causes of morbidity and mortality throughout the world. COPD and its complications also lead to a large number of deaths every year in our country. Cardiac arrhythmias and sudden cardiac death are the major complications of COPD leading to death and disability. Such cardiac complications are often a result of autonomic dysfunction. Aims and Objectives: This study aims to find out the autonomic dysfunction in moderate COPD patients by comparing their heart rate variability (HRV) parameters with age and sex matched healthy controls. Materials and Methods: After obtaining approval from the Institutional Ethics Committee, 48 patients of moderate COPD and 54 healthy subjects were assessed and compared with respect to their HRV parameters which included Mean RR, Mean HR, SDNN, NN50, pNN50, root mean square of successive differences (RMSSD), high frequency (HF), low frequency (LF), LF/HF ratio, and SD2/SD1 ratio. Results: It was found that in comparison to healthy controls, patients of moderate COPD had significant alteration in the following HRV parameters – Mean HR (P: 0.001), RMSSD (P: 0.002), SDNN (P: 0.015), NN50 (P: 0.001), pNN50 (P: 0.000), HF (NU/normalized unit) [P: 0.033], HF (%) [P: 0.002], LF (NU/normalized unit) [P: 0.033], LF (%) [P: 0.012], and LF/HF (P: 0.033). Conclusion: As there is a significant alteration of several HRV parameters in moderate COPD patients, we conclude that HRV measurement may subserve as a simple and non-invasive tool to assess autonomic dysfunction in patients of COPD at the earliest.

Parameter Identification Algorithm of Lumped Parameter Model in the Circle of Willis / 医用生物力学

Objective To explore the application of three parameter identification methods (impedance modulus curve method, impedance component method, and genetic algorithm) in solving parameter identification problem of the 11-element lumped parameter model in the circle of Willis. Methods Using the flow and pressure waveforms of the internal carotid arteries and vertebral arteries on both sides as inlet conditions, parameter values of the model under normal and bilateral vertebral artery stenosis conditions were calculated. The recognition algorithm was verified by using Simulink models, and finally the stability of the recognition algorithm was verified by adding a certain noise to the flow. Results Under normal circumstances, the proximal resistances obtained by the impedance modulus curve method were larger, and the resistances of the anterior communicating artery obtained by the impedance component method were larger. The genetic algorithm could obtain relatively reasonable model parameter values. In the case of vertebral artery stenosis on both sides, the impedance modulus curve method could obviously get the results of the increasement in proximal resistances of the posterior circulation, but the results obtained by the impedance component method and the genetic algorithm mainly lied in that the distal resistance had a larger increase. Conclusions There are still differences between the pressure data calculated by the parameters identified by the above three methods and the actual data, which are considered as modeling errors, source data errors and calculation errors. The impedance modulus curve method has a certain effect in distinguishing changes of the proximal and distal resistances, but there exist large errors in identification of some parameters. The impedance component method can identify the parameters, but this method is unstable with large calculation errors. Genetic algorithm can obtain a better approximate solution, but it has certain problems in distinguishing vertebral artery stenosis. The combination of impedance modulus curve method and genetic algorithm may play a better role in future application of this model for disease diagnosis.

An optical parameter imaging system with profile information fusion / 生物医学工程学杂志

There is a shared problem in current optical imaging technologies of how to obtain the optical parameters of biological tissues with complex profiles. In this work, an imaging system for obtaining the optical parameters of biological tissues with complex profile was presented. Firstly, Fourier transformation profilometry was used for obtaining the profile information of biological tissues, and then the difference of incident light intensity at different positions on biological tissue surface was corrected with the laws of illumination, and lastly the optical parameters of biological tissues were achieved with the spatial frequency domain imaging technique. Experimental results indicated the proposed imaging system could obtain the profile information and the optical parameters of biological tissues accurately and quickly. For the slab phantoms with height variation less than 30 mm and angle variation less than 40º, the maximum relative errors of the profile uncorrected optical parameters were 46.27% and 72.18%, while the maximum relative errors of the profile corrected optical parameters were 6.89% and 10.26%. Imaging experiments of a face-like phantom and a human's prefrontal lobe were performed respectively, which demonstrated the proposed imaging system possesses clinical application value for the achievement of the optical parameters of biological tissues with complex profiles. Besides, the proposed profile corrected method can be used to combine with the current optical imaging technologies to reduce the influence of the profile information of biological tissues on imaging quality.

Multi-task motor imagery electroencephalogram classification based on adaptive time-frequency common spatial pattern combined with convolutional neural network / 生物医学工程学杂志

The effective classification of multi-task motor imagery electroencephalogram (EEG) is helpful to achieve accurate multi-dimensional human-computer interaction, and the high frequency domain specificity between subjects can improve the classification accuracy and robustness. Therefore, this paper proposed a multi-task EEG signal classification method based on adaptive time-frequency common spatial pattern (CSP) combined with convolutional neural network (CNN). The characteristics of subjects' personalized rhythm were extracted by adaptive spectrum awareness, and the spatial characteristics were calculated by using the one-versus-rest CSP, and then the composite time-domain characteristics were characterized to construct the spatial-temporal frequency multi-level fusion features. Finally, the CNN was used to perform high-precision and high-robust four-task classification. The algorithm in this paper was verified by the self-test dataset containing 10 subjects (33 ± 3 years old, inexperienced) and the dataset of the 4th 2018 Brain-Computer Interface Competition (BCI competition Ⅳ-2a). The average accuracy of the proposed algorithm for the four-task classification reached 93.96% and 84.04%, respectively. Compared with other advanced algorithms, the average classification accuracy of the proposed algorithm was significantly improved, and the accuracy range error between subjects was significantly reduced in the public dataset. The results show that the proposed algorithm has good performance in multi-task classification, and can effectively improve the classification accuracy and robustness.

Parkinson's disease diagnosis based on local statistics of speech signal in time-frequency domain / 生物医学工程学杂志

For speech detection in Parkinson's patients, we proposed a method based on time-frequency domain gradient statistics to analyze speech disorders of Parkinson's patients. In this method, speech signal was first converted to time-frequency domain (time-frequency representation). In the process, the speech signal was divided into frames. Through calculation, each frame was Fourier transformed to obtain the energy spectrum, which was mapped to the image space for visualization. Secondly, deviations values of each energy data on time axis and frequency axis was counted. According to deviations values, the gradient statistical features were used to show the abrupt changes of energy value in different time-domains and frequency-domains. Finally, KNN classifier was applied to classify the extracted gradient statistical features. In this paper, experiments on different speech datasets of Parkinson's patients showed that the gradient statistical features extracted in this paper had stronger clustering in classification. Compared with the classification results based on traditional features and deep learning features, the gradient statistical features extracted in this paper were better in classification accuracy, specificity and sensitivity. The experimental results show that the gradient statistical features proposed in this paper are feasible in speech classification diagnosis of Parkinson's patients.

Optical coherence tomography versus intravascular ultrasound in patients with myocardial infarction: a diagnostic performance study of pre-percutaneous coronary interventions

Accurate coronary measurements are important in guiding percutaneous coronary intervention. Intravascular ultrasound is a widely accepted diagnostic modality for coronary measurement before percutaneous coronary intervention. The spatial resolution of optical coherence tomography is 10 times larger than that of intravascular ultrasound. The objective of the study was to compare quantitative and qualitative parameters of frequency domain optical coherence tomography (FDOCT) with those of intravascular ultrasound and coronary angiography in patients with acute myocardial infarction. Diagnostic parameters of coronary angiography, intravascular ultrasound, and FDOCT of 250 patients with coronary artery disease who required admission diagnosis were included in the analyses. Minimum lumen diameter detected by FDOCT was larger than that detected by quantitative coronary angiography (2.11±0.1 vs 1.89±0.09 mm, P<0.0001, q=34.67) but smaller than that detected by intravascular ultrasound (2.11±0.1 vs 2.19±0.11 mm, P<0.0001, q=12.61). Minimum lumen area detected by FDOCT was smaller than that detected by intravascular ultrasound (3.41±0.01 vs 3.69±0.01 mm2, P<0.0001). FDOCT detected higher numbers of thrombus, tissue protrusion, dissection, and incomplete stent apposition than those detected by intravascular ultrasound (P<0.0001 for all). More accurate and sensitive results of the coronary lumen can be detected by FDOCT than coronary angiography and intravascular ultrasound (level of evidence: III).

Choroid thickness changes in the macular area before and after idiopathic macular hole surgery / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To explore changes of choroidal blood flow post vitrectomy in idiopathic macular hole(IMH), and to discuss the role of choroidal microstructure changes abnormality in macular hole formation.<p>METHODS: Totally 56 eyes of 56 patients diagnosed with unilateral IMH were included(2014-05/2015-12). All patients received pars planar vitrectomy, indocyanine green assisted inner limiting membrane peeling combined with intraocular +12%C3F8 tamponade. Patients with cataract received phacoemulsification and intraocular lens implantation. Choroidal thicknesses were measured at 9 points before and at 1, 3 and 6mo after the surgery, namely the fovea, 1mm and, 3mm above, below, nasal and temporal to the fovea.<p>RESULTS: Preoperative SFCT value was 233.43±84.638μm, and at 1, 3, 6mo follow-up SFCT were 242.46±88.199μm, 238.97±89.252μm, and 236.71±88.661μm, respectively. SFCT at 1mo after surgery was significantly increased compared to preoperative thickness(<i>P</i><0.05). 1, 3, and 6mo after the surgery the choroidal thickness at 3mm below the fovea(ICT3mm)(179.63±62.941μm, 179.74±65.981μm, 180.80±58.379μm)gradually increased compared with those before the surgery(170.89±57.040μm). However, there was no significant difference between ICT3mm values at each time point. 1, 3, and 6mo after the surgery the choroidal thickness at 1mm below the fovea(ICT1mm)(216.31±80.297μm, 214.54±75.693μm, 205.69±68.697μm)compared with those before the surgery(207.37±67.502μm)have statistical significance. Compared 6mo after the surgery with 1mo after the surgery have statistical significance with ICT1mm values at each time point(<i>P</i><0.05).<p>CONCLUSION: SFCT of the study eyes showed a transient increase at 1mo follow up, then gradually returned to the base line. As the macular hole successfully closed, the choroidal thickness didn't not show difference compared with baseline, indicating that the decreasing in choroidal thickness is possibly the cause to the formation of the macular hole, not the results. IMH postoperative choroidal thickness values change by location, which may be due to the oppression by the injected gas in the macular hole surgery.

Application of heart rate variability in acupuncture research / 针刺研究

The measurement of heart rate variability (HRV) has the advantages of noninvasiveness and simple operation and is widely used in clinical trials and scientific research for assessing reactions of the autonomic nervous system. More and more studies on acupuncture also take HRV as an important index. In addition to the definition, origin, analytical methods, and significance of time domain and frequency domain parameters of HRV, we reviewed the situations of application of HRV to acupuncture research in recent years, analyzed the influence of acupuncture and sham acupuncture, different acupuncture methods, and different acupoints on HRV, and confirmed the role of HRV in reflecting the effect of acupuncture on the vagal and sympathetic systems. However, various interference factors for HRV measurement and diverse methods for data analysis may lead to great differences in the experimental results of HRV and the interpretation of parameters. Therefore, careful analysis is needed in future studies on acupuncture with HRV as an observation index.

The effect of optical magnification during retinal nerve fiber layer thickness measurement in different degrees of myopia by using frequency domain OCT / 中华实验眼科杂志

Objective To investigate the effect of optical magnification on retinal nerve fiber layer (RNFL)thickness in different degrees of myopia by using spectral domain optical coherence tonmography (SD-OCT).Methods A retrospective case control study was designed.Eighty-five healthy people who underwent myopia correction and physical examination in the ophthalmology department of the Second Affiliated Hospital of Zhengzhou University from September to December in 2017 were selected,one eye was randomly selected from each subject.All the subjects were divided into 20 cases of emmetropic group,21 cases of low myopia group,20 cases of moderate myopia group,and 24 cases of high myopia group according to diopter.The visual acuity,best corrected visual acuity,slit lamp microscopy,fundoscopy,intraocular pressure and axial measurement,SD-OCT and visual field examination were performed on all the subjects.The difference of the mean RNFL and the thickness of the peripapillary quadrants among different groups,and relationship between RNFL and length of eye axis or diopter were analyzed before and after the correction of optical magnification.This study followed the Declaration of Helsinki.Results Before optical magnification correction,the average thickness of average,upper,lower and nasal quadrants RNFL were negatively correlated with the length of ocular axis (r =-0.595,-0.493,-0.639,-0.500;all at P =0.000),positively correlated with the diopter (r =0.005,0.565,0.600,0.464;all at P =0.000);the thickness of temporal quadrant RNFL was positively correlated with the length of ocular axis (r--0.683,P =0.000),negatively correlated with the diopter (r =-0.730,P =0.000).After optical magnification correction,the thickness of average,upper,lower and nasal quadrants RNFL had no correlation with the length of ocular axis and diopter (all at P＞0.05);the thickness of temporal quadrant RNFL was positively correlated with the length of ocular axis (r =0.840,P =0.000),negatively correlated with the diopter (r=-0.855,P =0.000).Before optical magnification correction,the thickness of average,upper,lower and nasal quadrants RNFL in emmetropic group were significantly higher than those of the other three groups (all at P＜0.05).The thickness of temporal quadrant RNFL was significantly lower than those in the other three groups (all at P＜0.05).The thickness of average,upper,lower and nasal quadrants RNFL in high myopia group were significantly lower than those in low myopia group and moderate myopia group (all at P ＜ 0.05),while the thickness of temporal quadrant RNFL was significantly higher than those in low myopia group and moderate myopia group (all at P＜0.05).There was no significant difference in RNFL thickness between low myopia group and moderate myopia group (all at P＞0.05).After optical magnification correction,the thickness of average,upper,lower and nasal quadrants RNFL showed no significant differences among the 4 groups (all at P＞0.05).The thickness of temporal quadrant RNFL was significantly different among the 4 groups (F =58.313,P =0.000).Conclusions When measuring RNFL thickness in myopic eyes by SD-OCT,the longer the axial length,the more obvious the optical magnification effect.The thickness of temporal quadrant RNFL increases in high myopia patients,so glaucoma should be vigilant when the thickness of temporal quadrant RNFL decreases.

Role of the optic disc parameters and retinal thickness measured by frequency domain OCT in early glaucoma diagnosis / 眼科新进展

Objective To explore the roles of frequency domain OCT in measuring the retinal thickness around the optic disc and optic disc parameters in early glaucoma diagnosis.Methods The optic disc parameters and retinal nerve fiber layer (RNFL) thickness in the 40 healthy volunteers (control group) and 85 cases of primary open angle glaucoma (POAG),including 36 patients as the early glaucoma subgroup and 49 patients as the glaucoma evolutum subgroup,were measured by frequency domain OCT.Then,the correlation analysis of RNFL thickness,optic disc parameters and the mean deviation (MD) of visual field in each group was performed,and the area under the curve was used to evaluate the diagnostic efficiency of RNFL thickness around the optic disc and optic disc parameters in the diagnosis of glaucoma.Results The RNFL thickness and the complete cycle mean RNFL thickness in the temporal,upper,nasal and inferior quadrant in the glaucoma patients were significantly lower than those in the controls (all P ＜ 0.05),and the above indexes in the glaucoma evolutum subgroup were significantly decreased compared with those in the early glaucoma subgroup (all P ＜ 0.05).There were statistically significant differences in the optic disc parameters between the groups except the optic disc area (all P ＜ 0.05).Pearson correlation analysis showed the RNFL thickness and the complete cycle mean RNFL thickness in the temporal,upper and inferior quadrant were negatively correlated with the MD in the glaucoma patients (all P ＜ 0.05),and the parameter of optic cup volume and cup/disc area ratio were positively correlated with the MD (both P ＜ 0.05),and the rim area,rim volume and disc volume were negatively correlated with MD (all P ＜ 0.05).The ROC curve analysis showed that the largest area under the curve of RNFL thickness in the inferior quadrant of the optic disc region was 0.886,and the specificity and sensitivity was 0.775 and 0.924,respectively.Moreover,the area under the curve of the optic cup/optic disc area was the largest,with sensitivity and specificity of 0.741 and 0.815,respectively.Conelusion OCT for measuring optic disc structure and RNFL thickness can be used for early diagnosis of glaucoma,and it has a high sensitivity and specificity.

A research for single trial detection of error related negativity / 生物医学工程学杂志

Error related negativity (ERN) is generated in frontal and central cortical regions when individuals perceive errors. Because ERN has low signal-to-noise ratio and large individual difference, it is difficult for single trial ERN recognition. In current study, the optimized electroencephalograph (EEG) channels were selected based on the brain topography of ERN activity and ERN offline recognition rate, and the optimized EEG time segments were selected based on the ERN offline recognition rate, then the low frequency time domain and high frequency time-frequency domain features were analyzed based on wavelet transform, after which the ERN single detection algorithm was proposed based on the above procedures. Finally, we achieved average recognition rate of 72.0% ± 9.6% in 10 subjects by using the sample points feature in 0~3.9 Hz and the power and variance features in 3.9~15.6 Hz from the EEG segments of 200~600 ms on the selected 6 channels. Our work has the potential to help the error command real-time correction technique in the application of online brain-computer interface system.

Research on Automatic Identification System of Traditional Chinese Medicine Constitution Based on Pulse Wave / 世界科学技术-中医药现代化

This study was aimed to explore the feasibility of identification of traditional Chinese medicine (TCM) constitution based on photoplethysmography (PPG) frequency domain analysis,and to establish an automatic identification system (AIS) of TCM constitution with simple operation and good generalization.The Classification and Determination of Constitution in TCM was used to evaluate the subjects' constitutional state.Pulse wave sensor was used to collect the pulse wave signal.Spectral characteristics were analyzed by power spectrum analysis.Eight classification algorithms of data mining were used to establish the model of qi-insufficiency constitution.The results showed that the pulse wave harmonic peak was that qi-insufficiency constitution was higher than health group;the model was optimal when random forest algorithm was used;and the accuracy of 10-CV test was 80.4％.Sensitivity reached 73.2％.Specificity and receiver operator characteristic were all above 0.8.The model has certain reliability.It was concluded that it was feasible to identify qiinsufficiency constitution by means of frequency domain analysis of PPG.It provides preliminary work for the construction of AIS of TCM constitution as well as a simple and quick assistant tool for the constitution identification of subhealth group in family health care.

Effects of two fatigue protocols on lower extremity kinematics and time/frequency-domain characteristics of impact forces during drop landing / 医用生物力学

Objective To compare the influence of two fatigue protocols on kinematics of lower extremities as well as time/frequency-domain characteristics of impact force during human landing. Methods A total of 15 trained male athletes (sprint/jumping events) were selected and their kinematics in sagittal/frontal plane and time/frequency-domain characteristics of ground reaction force (GRF) under pre- and post-fatigue conditions with two fatigue protocols (constant speed running, shuttle running + vertical jumping) were collected by the Vicon motion capture system and Kistler 3D force plates. Results (1) Both fatigue protocols showed a significant decrease in the angle of hip and knee joints on the sagittal plane, and an increase in the flexion range of motion (ROM). The running + jumping fatigue protocol showed a significant increase in the flexion ROM of ankle joint, the maximum flexion angular velocity of knee joint (P<0.05), the abduction ROM of hip joint and the maximum abduction angular velocity of hip and knee joints (P<0.05). (2) No significant differences were found in time/frequency-domain characteristics of impact force between pre- and post-tests for both fatigue protocols. The running and running + jumping fatigue protocols showed lower amplitude spectra of the GRF in the frequency domain at 3.51, 8.20 Hz and 1.17, 3.51, 7.03 Hz, respectively (P<0.05). Conclusions Both fatigue protocols can induce a more flexed landing posture of lower extremities under the impact of landing, and the running + jumping fatigue protocol shows a better effect with shorter intervention time, which indicates such fatigue protocol has more advantages from the perspective of experimental methodology. The research findings can provide further references for studying force characteristics after fatigue.

Effects of two fatigue protocols on lower extremity kinematics and time/frequency-domain characteristics of impact forces during drop landing / 医用生物力学

Objective To compare the influence of two fatigue protocols on kinematics of lower extremities as well as time/frequency-domain characteristics of impact force during human landing.Methods A total of 15 trained male athletes (sprint/jumping events) were selected and their kinematics in sagittal/frontal plane and time/frequency-domain characteristics of ground reaction force (GRF) under pre-and post-fatigue conditions with two fatigue protocols (constant speed running,shuttle running + vertical jumping) were collected by the Vicon motion capture system and Kistler 3 D force plates.Results (1) Both fatigue protocols showed a significant decrease in the angle of hip and knee joints on the sagittal plane,and an increase in the flexion range of motion (ROM).The running + jumping fatigue protocol showed a significant increase in the flexion ROM of ankle joint,the maximum flexion angular velocity of knee joint (P＜0.05),the abduction ROM of hip joint and the maximum abduction an gular velocity of hip and knee joints (P ＜ 0.05).(2) No significant differences were found in time/frequency-domain characteristics of impact force between pre-and post-tests for both fatigue protocols.The running and running + jumping fatigue protocols showed lower amplitude spectra of the GRF in the frequency domain at 3.51,8.20 Hz and 1.17,3.51,7.03 Hz,respectively (P＜0.05).Conclusions Both fatigue protocols can induce a more flexed landing posture of lower extremities under the impact of landing,and the running + jumping fatigue protocol shows a better effect with shorter intervention time,which indicates such fatigue protocol has more ad vantages from the perspective of experimental methodology.The research findings can provide further references for studying force characteristics after fatigue.

System study on magneto-acoustic imaging in frequency domain / 医疗卫生装备

Objective To design a new frequency domain magnato-aoustic imaging system to image the conductivity of medium.Methods A continuous sine wave signal was adopted to stimulate the MAT signal. The lock-in technique was applied to measuring the amplitude and phase of the magneto-acoustic signal. The drive control program of the imaging system was designed using virtual instrument tools. The experiments were conducted on the phantom made of coper wire.Results The amplitude precision was improved up to 10-7 Pa, while the system could locate the sonic source with locating precision of millimeter.Conclusion A new magneto-acoustic imaging system is proposed with high locating precision as well as low frequency excitation, which is significative to the study on the sonic source theory and improvement of the imaging precision.

The role of pulse oximetry plethysmographic waveform monitoring as a marker of restoration of spontaneous circulation:a pilot study / 中华危重病急救医学

ObjectiveTo investigate the feasibility of using pulse oximetry plethysmographic waveform (POP) to identify the restoration of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR).Methods An observational research was conducted. A porcine model of ventricular fibrillation (VF) arrest was reproduced. After 3 minutes of untreated VF, animals received CPR according to the latest CPR guidelines, providing chest compressions to a depth of 5 cm with a rate of 105 compressions per minute and instantaneous mechanical ventilation. After 2 minutes of CPR, animals were defibrillated with 100 J biphasic, followed by continuous chest compressions. Data of hemodynamic parameters, partial pressure of end-tidal carbon dioxide (PETCO2) and POP were collected. The change in POP was observed, and the characteristics of changes of the waves were recorded during the peri-CPR period using the time and frequency domain methods.Results VF was successfully induced in 6 pigs, except 1 death in anesthesia induction period.① After VF, invasive blood pressure waveform and POP of the animals disappeared. PETCO2 was (18.83±2.71) mmHg (1 mmHg=0.133 kPa), and diastolic arterial pressure was (23.83±5.49) mmHg in compression stage. Animals attained ROSC within 1 minute after defibrillation, with PETCO2 [(51.83±9.35) mmHg] and diastolic arterial pressure [(100.67±10.97) mmHg] elevated significantly compared with that of compression stage (t1 = 8.737,t2 = 25.860, bothP = 0.000), with appearance of arterial blood pressure waveform.② Characteristic changes in POP were found in all experimental animals. During the stages of induced VF, compression, ROSC, and compression termination, POP showed characteristic waveform changes. POP showed disappearance of waveform, regular compression wave, fluctuation hybrid and stable pulse wave in time domain method; while in the frequency domain method waveform disappearance, single peak of compression, double or fusion peak and single peak of pulse were observed.Conclusion Analysis of POP using time and frequency domain methods could not only quickly detect cardiac arrest, but also show a role as a feasible, non-invasive marker of ROSC during CPR.

Heart rate variability and arrhythmias evaluated with Holter in dogs with degenerative mitral valve disease / Variabilidade da frequência cardíaca e arritmias detectadas pelo exame Holter em cães com degeneração valvar mitral

Cardiac diseases promote alterations in the autonomic control of the heart, leading to an increase in heart rate and, as a result, a decrease in heart rate variability (HRV).The aim of this study was to evaluate if the development of heart failure secondary to degenerative mitral valve disease (DMVD) concurs with changes in autonomic modulation of heart rhythm which are assessed by long electrocardiography examination (Holter). Dogs were evaluated by clinical examination and echocardiography in order to be categorized into the following groups: Control (healthy; n=6), DMVD (disease without heart failure; n=8), and DMVD heart failure (disease with heart failure; n=13). Arrhythmias and frequency domain HRV were determined by Holter. Diseased animals, when compared to healthy, had significantly lower total power, which indicates overall HRV. DMVD heart failure dogs also showed other disturbances such as high incidence of supraventricular arrhythmias, high heart rate, little amount of pauses (2.0s long between consecutive heartbeats), longer time in tachycardia, shorter time in bradycardia, low high frequency (parasympathetic control), and high low frequency (sympathetic and parasympathetic control) when compared to control (p<0.05). In DMVD dogs, Holter-derived variables changed with the development of heart failure...

As cardiopatias cursam com alterações do controle autonômico do coração, resultando em taquicardia e consequente diminuição na variabilidade da frequência cardíaca (VFC). O objetivo deste estudo foi avaliar se o desenvolvimento de insuficiência cardíaca secundária à degeneração valvar mitral (DVM) leva a alterações no controle autonômico do coração, as quais podem ser determinadas pela eletrocardiografia contínua (Holter). Cães foram distribuídos em grupos experimentais após avaliação clínica e ecocardiográfica da seguinte maneira: controle (saudáveis; n=6), DVM sem insuficiência cardíaca (n=8) e DVM com insuficiência cardíaca (n=13). Arritmias e VFC foram determinadas pelo Holter. Animais portadores de DVM, quando comparados ao controle, apresentaram diminuição significativa da potência total, a qual é representativa de toda a VFC. Somente cães doentes e com insuficiência cardíaca apresentaram incidência elevada de arritmias supraventriculares, frequência cardíaca aumentada, pequena quantidade de pausas superiores a 2,0s entre batimentos consecutivos, permanência por mais tempo em taquicardia do que em bradicardia, diminuído índice de alta frequência (indicativo de controle parassimpático) e elevado índice de baixa frequência (indicativo de controle simpático e parassimpático), quando comparados ao controle (p<0,05). Assim, conclui-se que, em cães portadores de DVM, as variáveis obtidas com o Holter apresentam-se alteradas devido ao desenvolvimento de insuficiência cardíaca...

Parameter identification algorithm for fault location using one terminal data based on frequency domain / 西安交通大学学报·英文版

This paper presents a novel algorithm of fault location for transmission line. Solving the network spectrum equations for different frequencies the fault can be located accurately by this algorithm with one terminal data of voltage and current, and the identified parameters, such as fault distance, fault resistance, and opposite terminal system resistance and inductance. The algorithm eliminates the influence of the opposite system impedance on the fault location accuracy, which causes the main error in traditional fault location methods using one terminal data. A method of calculating spectrum from sampled data is also proposed. EMTP simulations show the validity and higher accuracy of the fault location algorithm compared to the existing ones based on one terminal data.

Study on lift-up speed of aerodynamic compliant foil thrust bearings / 药物分析学报

Objective The experimental study on the lift-up speed of a new kind of compliant aerodynamic foil thrust bearings was performed on the multifunctional test rig established for testing the performances of foil gas bearings. Methods The lift-up speed of foil gas thrust bearing under given axial load was analyzed through the spectrum of axial displacement response in frequency domain. Results The test results indicated that the difference in the spectrum of axial displacement responses before and after lifting up of the rotor was obvious. After lifting up of the rotor, there were only larger components of rotation frequency and lower harmanic frequencies. If the rotor wasn't lift-up, there were also larger components of other frequencies in the spectrum. Conclusion So by analyzing the spectrum of axial displacement response, the results showed that the lift-up speed was about 1 860 rpm when the axial load was 31N.