Electric and electronic products are required to pass through the certification on electrical safety performance before entering into the market in order to reduce electrical shock and electrical fire so as to protect the safety of people and property. The leakage current is the most important factor in testing the electrical safety performance and the test theory is based on the perception current effect and threshold. The traditional method testing the current threshold for perception only depends on the sensing of the human body and is affected by psychological factors. Some authors filter the effect of subjective sensation by using physiological and psychological statistical algorithm in recent years and the reliability and consistency of the experiment data are improved. We established an experiment system of testing the human body's current threshold for perception based on EEG feature analysis, and obtained 967 groups of data. We used wavelet packet analysis to detect α wave from EEG, and used FFT to do spectral analysis on α wave before and after the current flew through the human body. The study has shown that about 97.72% α wave energy changes significantly when electrical stimulation occurs. It is well proved that when the EEG feature identification is applied to test the human body current threshold for perception, and meanwhile α wave energy change and human body sensing are used together to confirm if the current flowing through the human body reaches the perception threshold, the measurement of the human body current threshold for perception could be carried out objectively and accurately.
ObjectiveThis paper aimed to summarize the new progress in surgical indications regarding as maximum diameter from evidence-based medical evidence and morphological rupture-risk assessment of abdominal aortic aneurysms (AAA) and its clinical application value.MethodThe rupture-risk and its mechanism of AAA in specific population and morphological characteristics were reviewed.ResultsAsymptomatic patients in specific subgroups may also benefit from AAA repair by lowering the intervention threshold. Besides the maximum diameter of aneurysm, other morphological factors, such as the true geometric shape, the wall thickness, and mural thrombus also had important predictive value for AAA rupture risk.ConclusionRupture-risk assessment based on the actual individual situation of AAA patients can further facilitate the clinical diagnosis and treatment.
It is difficult to distinguish the inferior alveolar nerve (IAN) from other tissues inside the IAN canal due to their similar CT values in the X image which are smaller than that of the bones. The direct reconstruction, therefore, is difficult to achieve the effects. The traditional clinical treatments mainly rely on doctors' manually drawing the X images so that some subjective results could not be avoided. This paper proposes the partition reconstruction of IAN canal based on shape features. According to the anatomical features of the IAN canal, we divided the image into three parts and treated the three parts differently. For the first, the directly part of the mandibular, we used Shape-driven Level-set Algorithm Restrained by Local Information (BSLARLI) segment IAN canal. For the second part, the mandibular body, we used Space B-spline curve fitting IAN canal's center, then along the center curve established the cross section. And for the third part, the mental foramen, we used an adaptive threshold Canny algorithm to extract IAN canal's edge to find center curve, and then along it established the cross section similarly. Finally we used the Visualization Toolkit (VTK) to reconstruct the CT data as mentioned above. The VTK reconstruction result by setting a different opacity and color values of tissues CT data can perspectively display the INA canal clearly. The reconstruction result by using this method is smoother than that using the segmentation results and the anatomical structure of mental foramen position is similar to the real tissues, so it provides an effective method for locating the spatial position of the IAN canal for implant surgeries.
ObjectiveTo systematically review the non-inferiority trials in the cardiovascular domain that utilize medical devices as interventions, and investigate its characteristics and threshold settings. MethodsThe PubMed, Embase, and CENTRAL databases were electronically searched to collect non-inferiority trials in the cardiovascular field involving medical devices from inception to July 26, 2023. Two reviewers independently screened literature and extracted data. The reported information included basic characteristics, features of non-inferiority trials, and threshold-setting features of the included studies. Data analysis was performed using Excel 2020 and R 4.2.1 software. ResultsA total of 214 studies were included, with 167 studies (78.0%) focusing on interventions related to coronary artery stents. The trials predominantly utilized a two-arm design (92.9%), with a prevalent use of non-inferiority absolute thresholds (96.7%) as the criteria for non-inferiority determination. In 150 studies (70.1%), non-inferiority thresholds were established based on estimated control group effect values, while 33 studies (15.4%) did not report the source of these values. The non-inferiority trial endpoint outcomes exhibited diversity, and there were substantial differences in threshold settings. The three most studied qualitative indicators were target lesion failure rates (2.1%-8.6%), target vessel failure rates (2.5%-19.6%), and major adverse cardiovascular events rates (2.1%-10.0%). Late lumen loss (0.1-0.4 mm) emerged as the most frequently studied quantitative indicator. After converting absolute non-inferiority thresholds for all indicators into relative thresholds, the range was 1.20-3.67. ConclusionSignificant variations in non-inferiority threshold settings are observed for identical endpoint outcomes across included studies, highlighting a lack of reporting on the rationale behind threshold settings.
Abstract This experiment was to study the feasibility from direct observation of muscle contraction of the lower extremity fromelectrical stimulation threshold of nerve fascicle in identifying the Iα intrafusal afferent fibers during selective posterior rhizotomy (SPR) and to investigate the clinical relationship between the muscle spasm and the electrical stimulation of nerve fascicles. The electrical stimulation threshold of all nerve fascicles in 36 cases during SPR were analysed statistically. The results showed that there was a significant difference between the electrical stimulation threshold of the severed nerve fascicles and intact nerve fascicles no matter the nerve root or each posterior nerve rootlet was examined. It was simple and reliable for surgeons to identify correctly the Iα intrafusal afferent fibers intraoperatively from direct observation of the electrical stimulation threshold of nerve fascicle.
A de-noising method for electrocardiogram (ECG) based on ensemble empirical mode decomposition (EEMD) and wavelet threshold de-noising theory is proposed in our school. We decomposed noised ECG signals with the proposed method using the EEMD and calculated a series of intrinsic mode functions (IMFs). Then we selected IMFs and reconstructed them to realize the de-noising for ECG. The processed ECG signals were filtered again with wavelet transform using improved threshold function. In the experiments, MIT-BIH ECG database was used for evaluating the performance of the proposed method, contrasting with de-noising method based on EEMD and wavelet transform with improved threshold function alone in parameters of signal to noise ratio (SNR) and mean square error (MSE). The results showed that the ECG waveforms de-noised with the proposed method were smooth and the amplitudes of ECG features did not attenuate. In conclusion, the method discussed in this paper can realize the ECG de-noising and meanwhile keep the characteristics of original ECG signal.
Objective To introduce the multivariate random effects model (MREM) in the meta-analysis of diagnostic tests with multiple thresholds. Methods This paper expanded and extended the bivariate random effects model (BREM) to develop the MREM, and implemented it in the SAS Proc NLMIXED procedure. Results The MREM could obtain the study specific ROC curve for each study through empirical Bayes estimation, and the summary ROC curve located in between all study specific ROC curves evenly, while the BREM couldn’t obtain the study specific ROC curve. In addition, in the aspect of parameters estimation, the MREM didn’t depend on the choice of the diagnosis threshold and the type of SROC. The MREM could get only one SROC curve and its AUC was between the AUC of the 5 types of SROC from BREM, so it could avoid overestimation or underestimation. Conclusion The MREM can fully exploit the data, obtain stable and reliable results, and have a good application value in meta-analysis of diagnostic tests with multiple thresholds.
ObjectiveTo evaluate the prognosis of photocoagulation and (or) cryotherapy for prethreshold type 1 and threshold disease of retinopathy of prematurity (ROP).MethodsThe data of 29 eyes of 15 infants who were diagnosed as with prethreshold type 1 or threshold disease of ROP from Jan 30th, 2003 to Jan 13th, 2005 were retrospectively analysed. Pre- and post-operative conditions of ROP were compared in the follow up. Any related local and systemic complications were recorded.ResultsIn 29 eyes which had undergone photocoagulation and (or) cryotherapy, ROP regressed completely in 19 (65.5%), remained dragged retina was found in 7 (24.1%), and retinal detachment was seen in 3 (103%). ROP regressed completely in 12 eyes (41.4%) after the initial treatment and in 7 eyes (24.1%) after the secondary treatment. During the treatment, temporary corneal haze was found in 2 eyes, vitreous hemorrhage occurred in 1 eye, and inadvertent photocoagulation at macular area happened in 1 eye. No systemic complications were found in all cases.ConclusionTimely treatment of photocoagulation and (or) cryotherapy for prethreshold type 1 and threshold disease of ROP may lead to famous prognosis.(Chin J Ocul Fundus Dis,2005,21:278-281)
Red blood cell (RBC) transfusions are frequently used in cardiac surgery. A minority of patients assume most of the blood products transfusion during and after cardiac operations. Observational analysis of transfusion in patients undergoing cardiac surgery has uniformly demonstrated that RBC transfusion is associated with a significantly increasing risk of all-cause mortality and other serious adverse outcomes. In addition, it is an established fact that such patients can tolerate relatively low hemoglubin (Hb) levels. Consequently, it becomes widely accepted that appropriate limitation of transfusions could confer a substantial benefit to patients and decrease the use of limited resource. As a result, a restrictive threshold for blood transfusion is likely to be favored under most circumstances. However, an increasing amount of data differing from the observational analysis shows that clinical outcomes in patients who received transfusions with restrictive thresholds for Hb level are not superior to those with liberal thresholds. It has created a new uncertainty regarding the use of a restrictive threshold for transfusion during the perioperative period of cardiac surgery.
ObjectiveTo observe the safety and effectiveness of targeted navigation laser with continuous wave threshold power in the treatment of chronic central serous chorioretinopathy (CCSC).MethodsA retrospective clinical study. From November 2018 to June 2020, 28 eyes of 28 patients with CCSC diagnosed in the Eye Hospital of Nanjing Medical University were included in the study. Among them, there were 17 males with 17 eyes and 11 females with 11 eyes; all of them had a monocular disease. The average age of the patients was 36.24±5.14 years, and the average course of the diseases was 4.7±1.3 months. All affected eyes underwent best corrected visual acuity (BCVA), fluorescein fundus angiography, fundus autofluorescence, frequency domain optical coherence tomography and angiography, multifocal electroretinogram (mf-ERG) and micro field inspection. BCVA was carried out using the international standard visual acuity chart, which was converted into the logarithmic minimum angle of resolution (logMAR) visual acuity during statistics. A targeted navigation laser system was used for continuous wave power therapy under the threshold. Two weeks and 1, 3 months after treatment, the same equipment and methods as before treatment were used to perform related examinations to observe the BCVA, subfoveal choroidal thickness (SFCT), foveal retinal thickness (CMT), the mean light sensitivity (MS) in the 10° range of the macular center, and the amplitude density of P1 wave at ring 1 and 2. The t test was used to compare CMT, SFCT, retinal amplitude density and MS before and after treatment.ResultsBefore treatment and 2 weeks, 1 and 3 months after treatment, the average logMAR BCVA of the eyes were 0.74±0.16, 0.57±0.16, 0.22±0.05, 0.21±0.06, and the average CMT was 512.33±31.56, 350.40±36.61, 256.49±22.38, 253.45±23.65 μm respectively, the average SFCT was 462.82±25.38, 462.37±39.54, 461.51±29.36, 461.25±34.55 μm, the average MS was 16.32±5.41, 17.53±4.23, 19.52±4.12, 21.35±2.77 dB respectively. At different times before and after treatment, BCVA (t=6.52, 5.71, 6.01; P=0.00, 0.00, 0.00), CMT (t=3.08, 6.57, 4.90; P=0.01, 0.00, 0.00), SFCT (t=7.01, 6.54, 4.85; P=0.08, 0.07, 0.17), MS (t=6.17, 4.25, 5.46; P=0.02, 0.00, 0.00), the difference was statistically significant. The amplitude density of P1 wave at ring 1 in the affected eye was 64.37±18.25, 85.31±13.98, 98.35±14.52, 98.40±22.17 nV/deg2, and the amplitude density of P1 wave at ring2 was 36.12±18.32, 44.02±17.15, 62.35±14.85, 63.17±15.79 nV/deg2. The amplitude density of P1 wave at ring 1 (t=5.11, 9.03, 4.27; P=0.03, 0.00, 0.00) and ring 2 (t=5.11, 9.03, 4.27; P=0.03, 0.00, 0.00) before and after treatment showed statistical significance.ConclusionTargeted navigation laser continuous wave threshold power treatment for CCSC can increase the BCVA, macular retinal amplitude density and macular foveal MS, and reduce CMT and SFCT.