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        find Keyword "threshold" 33 results
        • Brain functional network reconstruction based on compressed sensing and fast iterative shrinkage-thresholding algorithm

          The construction of brain functional network based on resting-state functional magnetic resonance imaging (fMRI) is an effective method to reveal the mechanism of human brain operation, but the common brain functional network generally contains a lot of noise, which leads to wrong analysis results. In this paper, the least absolute shrinkage and selection operator (LASSO) model in compressed sensing is used to reconstruct the brain functional network. This model uses the sparsity of L1-norm penalty term to avoid over fitting problem. Then, it is solved by the fast iterative shrinkage-thresholding algorithm (FISTA), which updates the variables through a shrinkage threshold operation in each iteration to converge to the global optimal solution. The experimental results show that compared with other methods, this method can improve the accuracy of noise reduction and reconstruction of brain functional network to more than 98%, effectively suppress the noise, and help to better explore the function of human brain in noisy environment.

          Release date:2020-12-14 05:08 Export PDF Favorites Scan
        • Design of training system for foot ulcer patients based on three axis accelerometer

          The paper introduces a training system for foot ulcer patients based on three axis accelerometer, which uses three axis accelerometer and Apple mobile phone platform to guide foot ulcer patients to carry out a variety of lower limb muscle tissues training. The acceleration values of three directions for the foot training is obtained by analog-to-digital conversion and transmitted to the Apple mobile phone via its Bluetooth low energy. The Apple mobile phone accomplishes acceleration data preprocessing, numerical filtering and adaptive dual-threshold processing by our developed application program, so as to achieve the purpose of foot gesture recognition. The experimental result shows that the design can effectively present the training situation and effect of patients, encourage patients to adhere to the training, and provide some reference data for doctors and patients.

          Release date:2017-08-21 04:00 Export PDF Favorites Scan
        • Observation of the curative effect of targeted navigation laser with continuous wave power under the threshold in the treatment of chronic central serous chorioretinopathy

          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.

          Release date:2021-09-16 05:17 Export PDF Favorites Scan
        • Application of Auditory Brainstem Response in the Hearing Loss and Prognosis Research on Neonatal Hypoxic Ischemic Encephalopathy

          Objective Application of auditory brainstem response (ABR) in the study on the relationship of neonates with hypoxic-ischemic encephalopathy (HIE) and the children with hearing loss and auxiliary determine the prognosis of encephalopathy. Methods We prospectively selected neonates diagnosed as HIE in the department of neonatology of the Chengdu Women and Children Central Hospital from January, 2006 to June, 2008. Neonatal ABR was tested and the prognosis of neonates were observed through 3-year followed up in order to analyze the relationship between HIE severity and the severity of hearing handicap and the relationship between the severity of hearing handicap and prognosis. Statistical analysis was performed using SPSS 18.0. χ2 test was used to compare the rate between groups. Results 40 cases involving 80 ears were included, of which 33 cases accomplished the 3-year follow-up for prognosis. The results showed that, 86.3% HIE neonates had hearing handicap (mainly mild hearing loss, 40.0%). Medium-severe HIE groups had more serious hearing handicap than Mild HIE group with a statistical significance (continuity correction χ2=7.383, P=0.007). ABR results showed that, mild HIE is mainly manifested as I wave PL prolonged or poorly differentiated, accounting for 78.1%; medium - severe HIE are mainly manifested as III and V wave PL prolonged central segment abnormalities, accounting for 95.8%; the hearing threshold no more than 60 dB group had better prognosis than the hearing threshold more than 60 dB group prognosis (Fisher exact probability P=0.001). Conclusion ABR reflects that HIE severity and was positively related to the severity of hearing handicap. The more serious hearing loss in neonates is, the worse prognosis the neonates have. ABR can be used to assist the assessment of the prognosis of neonatal HIE.

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        • Research on automatic removal of ocular artifacts from single channel electroencephalogram signals based on wavelet transform and ensemble empirical mode decomposition

          The brain-computer interface (BCI) systems used in practical applications require as few electroencephalogram (EEG) acquisition channels as possible. However, when it is reduced to one channel, it is difficult to remove the electrooculogram (EOG) artifacts. Therefore, this paper proposed an EOG artifact removal algorithm based on wavelet transform and ensemble empirical mode decomposition. Firstly, the single channel EEG signal is subjected to wavelet transform, and the wavelet components which involve EOG artifact are decomposed by ensemble empirical mode decomposition. Then the predefined autocorrelation coefficient threshold is used to automatically select and remove the intrinsic modal functions which mainly composed of EOG components. And finally the ‘clean’ EEG signal is reconstructed. The comparative experiments on the simulation data and the real data show that the algorithm proposed in this paper solves the problem of automatic removal of EOG artifacts in single-channel EEG signals. It can effectively remove the EOG artifacts when causes less EEG distortion and has less algorithm complexity at the same time. It helps to promote the BCI technology out of the laboratory and toward commercial application.

          Release date:2021-08-16 04:59 Export PDF Favorites Scan
        • New advances in the study of subthreshold micropulse laser photocoagulation for central serous chorioretinopathy

          Central serous chorioretinopathy (CSC) is a common macular disease, which can lead to the loss of central vision in young patients. Although the disease is self-limited to some extent, there is no shortage of patients with prolonged course and recurrent attacks, eventually leading to irreversible visual impairment. Therefore, taking reasonable treatment in a certain period is particularly important for the visual prognosis of patients. Although thermal laser photocoagulation of leakage points and photodynamic therapy (PDT) have achieved good effects, there are risks of retinal damage and retinal pigment epithelium atrophy. Subthreshold micropulse laser (SMLP) is a kind of subthreshold short pulse laser, which does not cause visible damage to the retina and is safer. In the era of lack of PDT drugs, SMLP has gradually become an important means of clinical treatment for CSC, especially for patients with no obvious leakage point or subfoveal leakage point. An in-depth understanding of the mechanism of action of SMLP and its efficacy and safety in the treatment of CSC is helpful for the promotion and application of SMLP in the clinical treatment of CSC.

          Release date:2023-05-18 10:05 Export PDF Favorites Scan
        • Advances in surgical indications and morphological rupture-risk assessment of abdominal aortic aneurysms

          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.

          Release date:2019-08-12 04:33 Export PDF Favorites Scan
        • A guideline for determining the effect size decision threshold of health outcomes

          In the clinical evidence-based decision-making process, factors including benefits and harms, evidence certainty, cost and feasibility of interventions should be considered based on the best evidence. The development of decision threshold of effect size (DTES) for patient health outcomes can help stakeholders understand the benefits and harms of interventions, assess evidence certainty, and interpret research results. Based on international experience, the MERGE Working Group through group discussions, semi-structured interviews, expert consensus, and pilot application developed a set of 8-step guidelines for the development of DTES for health outcomes. These steps included necessity assessment, formation of working groups, selection of patient important outcomes, creation of scenarios based on the best evidence, design of expert consultation questionnaires, analysis of expert consultation results, face-to-face expert consensus, dissemination of the application and reevaluation. The DTES guideline development is intended to provide methodological guidance for stakeholders to develop DTES for health outcome indicators in different domains.

          Release date:2024-05-13 09:34 Export PDF Favorites Scan
        • Observation on the efficacy of conbercept combined with subthreshold micropulsed laser photocoagulation in the treatment of diabetic macular edema

          ObjectiveTo observe the efficacy of intravitreal injection of conbercept (IVC) combined with subthreshold micropulse laser photocoagulation (SMLP) in the treatment of diabetic macular edema (DME). MethodsA randomized controlled trial. From December 2020 to January 2022, 100 patients (100 eyes) with DME diagnosed by examination in Shanxi Aier Eye Hospital were included in the study. The patients were randomly divided into IVC group (50 eyes) and IVC+SMLP group (50 eyes). All the eyes were treated with IVC once a month for 3 times, and the eyes in IVC+SMLP group were treated with SMLP within 2 weeks after IVC. All affected eyes were examined by best corrected visual acuity (BCVA), which was statistically converted to logarithm of the minimum angle of resolution (logMAR) visual acuity. The central macular thickness (CMT) was measured by optical coherence tomography. Before the treatment, the logMAR BCVA of patients in IVC group and IVC+SMLP group were 0.56±0.04 and 0.55±0.03, respectively. The CMT were (437.36±11.35) μm and (434.58±10.88) μm, respectively. There was no significant difference in logMAR BCVA and CMT between the two groups (t= 0.476, 1.027; P>0.05). The patients were followed up for 12 months after treatment. The times of IVC and the changes of BCVA and CMT were compared between the two groups. Independent sample t-test was used to compare the logMAR BCVA, CMT and times of IVC between groups. ResultsAfter 12 months treatment, the logMAR BCVA of IVC group and IVC+SMLP group were (241.63±29.79) μm and (240.47±30.46) μm, respectively. Compared with those before treatment, 12 months after treatment, the BCVA of the two groups increased significantly (t=7.014, 5.608; P<0.001), while CMT decreased significantly (t=8.126, 6.013; P<0.001). There was no significant difference in BCVA and CMT between the two groups (t=0.835, 0.764; P>0.05). The number of IVC in IVC group and IVC+SMLP group were (8.15±2.04) times and (5.91±1.80) times, respectively, and the difference was statistically significant (t=5.210, P<0.001). ConclusionsBoth IVC+SMLP and IVC alone can effectively reduce CMT and increase BCVA in patients with DME. Combination therapy can reduce the number of IVC.

          Release date:2023-02-17 09:35 Export PDF Favorites Scan
        • CLINICAL ANALYSIS OF ELECTRICAL STIMULATION THRESHOLD OF NERVE FASCICLE DURING SELECTIVE POSTERIOR RHIZOTOMY

          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.

          Release date:2016-09-01 11:10 Export PDF Favorites Scan
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          2. 射丝袜