ERP source tracking and localization from single trial EEG MEG signals

Electroencephalography (EEG) and magnetoencephalography (MEG), which are two of a number of neuroimaging techniques, are scalp recordings of the electrical activity of the brain. EEG and MEG (E/MEG) have excellent temporal resolution, they are easy to acquire, and have a wide range of applications in science, medicine and engineering. These valuable signals, however, suffer from poor spatial resolution and in many cases from very low signal to noise ratios. In this study, new computational methods for analyzing and improving the quality of E/MEG signals are presented. We mainly focus on single trial event-related potential (ERP) estimation and E/MEG dipole source localization. Several methods basically based on particle filtering (PF) are proposed. First, a method using PF for single trial estimation of ERP signals is considered. In this method, the wavelet coefficients of each ERP are assumed to be a Markovian process and do not change extensively across trials. The wavelet coefficients are then estimated recursively using PF. The results both for simulations and real data are compared with those of the well known Kalman Filtering (KF) approach. In the next method we move from single trial estimation to source localization of E/MEG signals. The beamforming (BF) approach for dipole source localization is generalized based on prior information about the noise. BF is in fact a spatial filter that minimizes the power of all the signals at the output of the filter except those that come from the locations of interest. In the proposed method, using two more constraints than in the classical BF formulation, the output noise powers are minimized and the interference activities are stopped.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Senior Managers’ Viewpoints Toward Challenges of Implementing Clinical Governance: A National Study in Iran

Background: Quality improvement should be assigned as the main mission for healthcare providers. Clinical Governance (CG) is used not only as a strategy focusing on responding to public and government’s intolerance of poor healthcare standards, but also it is implemented for quality improvement in a number of countries. This study aims to identify the key contributing factors in the implementation process of CG from the viewpoints of senior managers in curative deputies of Medical Universities in Iran. Methods: A quantitative method was applied via a questionnaire distributed to 43 senior managers in curative deputies of Iran Universities of Medical Sciences. Data were analyzed using SPSS. Results: Analysis revealed that a number of items were important in the successful implementation of CG from the senior managers’ viewpoints. These items included: knowledge and attitude toward CG, supportive culture, effective communication, teamwork, organizational commitment, and the support given by top managers. Medical staff engagement in CG implementation process, presence of an official position for CG officers, adequate resources, and legal challenges were also regarded as important factors in the implementation process. Conclusion: Knowledge about CG, organizational culture, managerial support, ability to communicate goals and strategies, and the presence of effective structures to support CG, were all related to senior managers’ attitude toward CG and ultimately affected the success of quality improvement activities

ERP source tracking and localization from single trial EEG MEG signals

Electroencephalography (EEG) and magnetoencephalography (MEG), which are two of a number of neuroimaging techniques, are scalp recordings of the electrical activity of the brain. EEG and MEG (E/MEG) have excellent temporal resolution, they are easy to acquire, and have a wide range of applications in science, medicine and engineering. These valuable signals, however, suffer from poor spatial resolution and in many cases from very low signal to noise ratios. In this study, new computational methods for analyzing and improving the quality of E/MEG signals are presented. We mainly focus on single trial event-related potential (ERP) estimation and E/MEG dipole source localization. Several methods basically based on particle filtering (PF) are proposed. First, a method using PF for single trial estimation of ERP signals is considered. In this method, the wavelet coefficients of each ERP are assumed to be a Markovian process and do not change extensively across trials. The wavelet coefficients are then estimated recursively using PF. The results both for simulations and real data are compared with those of the well known Kalman Filtering (KF) approach. In the next method we move from single trial estimation to source localization of E/MEG signals. The beamforming (BF) approach for dipole source localization is generalized based on prior information about the noise. BF is in fact a spatial filter that minimizes the power of all the signals at the output of the filter except those that come from the locations of interest. In the proposed method, using two more constraints than in the classical BF formulation, the output noise powers are minimized and the interference activities are stopped

A study of the automated eddy current detection of cracks in steel plates

Applying life estimation approaches to determine in-service life of structures and plan the inspection schedules accordingly are becoming acceptable safety design procedures in aerospace. However, these design systems shall be fed with reliable parameters related to material properties, loading conditions and defect characteristics. In this context, the role of non-destructive (NDT) testing reliability is of high importance in detecting and sizing defects. Eddy current test (ECT) is an electromagnetic NDT method frequently used to inspect tiny surface fatigue cracks in sensitive industries. Owing to the new advances in robotic technologies, there is a trend to integrate the ECT into automated systems to perform NDT inspections more efficiently. In fact, ECT can be effectively automated as to increase the coverage, repeatability and scanning speed. The reliability of ECT scanning, however, should be thoroughly investigated and compared to conventional modes of applications to obtain a better understanding of the advantages and shortcomings related to this technique. In this contribution, a series of manual and automated ECT tests are carried out on a set of samples using a split-D reflection differential surface probe. The study investigates the level of noise recorded in each technique and discuss its dependency on different parameters, such as surface roughness and frequency. Afterwards, a description of the effect of crack orientation on ECT signal amplitude is provided through experimental tests and finite element simulations. Finally, the reliability of each ECT technique is investigated by means of probability of detection (POD) curves. POD parameters are then extracted and compared to examine the effect of scanning index, frequency and automation on detection reliability

A novel semiblind signal extraction approach for the removal of eye-blink artifact from EEGs

A novel blind signal extraction (BSE) scheme for the removal of eye-blink artifact from electroencephalogram (EEG) signals is proposed. In this method, in order to remove the artifact, the source extraction algorithm is provided with an estimation of the column of the mixing matrix corresponding to the point source eye-blink artifact. The eye-blink source is first extracted and then cleaned, artifact-removed EEGs are subsequently reconstructed by a deflation method. The a priori knowledge, namely, the vector, corresponding to the spatial distribution of the eye-blink factor, is identified by fitting a space-time-frequency (STF) model to the EEG measurements using the parallel factor (PARAFAC) analysis method. Hence, we call the BSE approach semiblind signal extraction (SBSE). This approach introduces the possibility of incorporating PARAFAC within the blind source extraction framework for single trial EEG processing applications and the respected formulations. Moreover, aiming at extracting the eyeblink artifact, it exploits the spatial as well as temporal prior information during the extraction procedure. Experiments on synthetic data and real EEG measurements confirm that the proposed algorithm effectively identifies and removes the eye-blink artifact from raw EEG measurements

The Diagnosis of Vocal Cord Movement Impairment Using Ultrasonography: A Comparison of Transthyroid and Suprathyroid Views

Background: Iatrogenic recurrent laryngeal nerve (RLN) injury is an uncommon but serious iatrogenic complication, especially after head and neck surgeries, and some thoracic procedures. Laryngoscopy can be an invasive and uncomfortable procedure; therefore, the use of ultrasonography (US) as a noninvasive method of screening patients for impaired vocal cord mobility is desirable. This study was conducted to compare the visibility of vocal cords in 2 suggested US views: suprathyroid and transthyroid approaches. Methods: In this clinical trial, 144 patients of either sex, who were candidates for elective suchlike surgery, were enrolled. The participants underwent vocal cord US through transthyroid and suprathyroid windows in a transverse plane with and without water bath. The visibility of vocal cords in either view was graded from 1 (invisible) to 5 (clearly visible). Direct laryngoscopy was performed  after surgeries, with anticipated risk of vocal cord dysfunction, in patients with suspicious or invisible vocal cords in US. Results: Symmetric movement of vocal cords was visible in 88.8% of the participants. The visibility of vocal cords in transthyroid view was better than the suprathyroid approach. The quality of sonographic views was better in females and in younger age groups. The application of water bath did not improve the overall visibility of vocal cords during US. Conclusions: Transthyroid US seem to be a valuable screening modality for anticipated vocal cord dysfunction. Application of this method, particularly in nonelderly women, conveys more favorable results. Future improvements in the ultrasound machines in the hands of well-trained clinicians will improve its diagnostic accuracy

Effects of phyzime enzyme in diet on growth performance, survival, digestibility, carcass composition and final production of farmed Siberian sturgeon, Acipenser baerii Brandt, 1869

An investigation was carried out to find the effects of different Smizyme phytase levels on growth indices, body composition and nutrient digestibility of farmed Siberian sturgeon, Acipenser baerii. One hundred and eighty fish (average weight 1.19 ± 0.017 kg) were distributed in nine concrete tanks (20 fish in each tank; area = 4 m2; depth = 80 cm) and divided to 3 treatments (F0, F1000 and F2000). Fish were fed for 62 days. Results showed that physaem addition in 2000 IU (F2000) to sturgeon commercial diet (38% protein and 12.5% crude fat) leads to significant increase in final weight, daily growth rate, specific growth rate and the decreased feed conversion ratio compared to the other two groups (p0.05). Body protein was declined in F1000 and F2000, while body lipid was elevated in F2000 (p0.05). Based on the results obtained from growth indices and digestibility coefficient, we suggest adding 2000 IU/kg Smizyme phytase in the fish diet

Effect of extraction of permanent first molars on the development and eruption of third molars

BACKGROUND AND AIM: It is required in many young patients that permanent first molars (PFMs) be extracted due to poor prognosis. This study investigates whether the extraction of such teeth is effective on the development of third molars and even their crown and root morphologies. METHODS: A total of 7000 panoramic radiographs were evaluated and 128 radiographs showing a history of extraction of PFMs on one side in one jaw or both jaws, with the third molars present in the same jaw on both sides, were selected. The third molar on the first molar extraction side was considered the case and the third molar on the other side was considered the control. The case and control third molars were compared in relation to their development, impaction, number of roots, mesiodistal width, root length, and curvature of apex. P < 0.05 was considered significant. Data were analyzed using SPSS software. RESULTS: On 128 panoramic radiographs evaluated, Olze and Demirjian factors showed that in most cases the crown development of the third molars on the control side lagged behind that on the case side. On the control side, the third molars had two roots in 66.9% and on the case side had two roots in 75.8%. CONCLUSION: Extraction of PFMs at a proper time might accelerate the development of the third molars on the same side and affect the morphologies of the crown and root(s) of third molars. KEYWORDS: Extraction; Permanent; Mola