Displaying publications 1 - 20 of 191 in total

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  1. Lim CS, Krishnan G, Sam CK, Ng CC
    Clin Chim Acta, 2013 Jan 16;415:158-61.
    PMID: 23043757 DOI: 10.1016/j.cca.2012.08.031
    Because blocking agent occupies most binding surface of a solid phase, its ability to prevent nonspecific binding determines the signal-to-noise ratio (SNR) and reliability of an enzyme-linked immunosorbent assay (ELISA).
    Matched MeSH terms: Signal-To-Noise Ratio
  2. Said MA, Musarudin M, Zulkaffli NF
    Ann Nucl Med, 2020 Dec;34(12):884-891.
    PMID: 33141408 DOI: 10.1007/s12149-020-01543-x
    OBJECTIVE: 18F is the most extensively used radioisotope in current clinical practices of PET imaging. This selection is based on the several criteria of pure PET radioisotopes with an optimum half-life, and low positron energy that contributes to a smaller positron range. In addition to 18F, other radioisotopes such as 68Ga and 124I are currently gained much attention with the increase in interest in new PET tracers entering the clinical trials. This study aims to determine the minimal scan time per bed position (Tmin) for the 124I and 68Ga based on the quantitative differences in PET imaging of 68Ga and 124I relative to 18F.

    METHODS: The European Association of Nuclear Medicine (EANM) procedure guidelines version 2.0 for FDG-PET tumor imaging has adhered for this purpose. A NEMA2012/IEC2008 phantom was filled with tumor to background ratio of 10:1 with the activity concentration of 30 kBq/ml ± 10 and 3 kBq/ml ± 10% for each radioisotope. The phantom was scanned using different acquisition times per bed position (1, 5, 7, 10 and 15 min) to determine the Tmin. The definition of Tmin was performed using an image coefficient of variations (COV) of 15%.

    RESULTS: Tmin obtained for 18F, 68Ga and 124I were 3.08, 3.24 and 32.93 min, respectively. Quantitative analyses among 18F, 68Ga and 124I images were performed. Signal-to-noise ratio (SNR), contrast recovery coefficients (CRC), and visibility (VH) are the image quality parameters analysed in this study. Generally, 68Ga and 18F gave better image quality as compared to 124I for all the parameters studied.

    CONCLUSION: We have defined Tmin for 18F, 68Ga and 124I SPECT CT imaging based on NEMA2012/IEC2008 phantom imaging. Despite the long scanning time suggested by Tmin, improvement in the image quality is acquired especially for 124I. In clinical practice, the long acquisition time, nevertheless, may cause patient discomfort and motion artifact.

    Matched MeSH terms: Signal-To-Noise Ratio
  3. Hameed HK, Wan Hasan WZ, Shafie S, Ahmad SA, Jaafar H, Inche Mat LN
    J Med Eng Technol, 2020 Apr;44(3):139-148.
    PMID: 32396756 DOI: 10.1080/03091902.2020.1753838
    To make robotic hand devices controlled by surface electromyography (sEMG) signals feasible and practical tools for assisting patients with hand impairments, the problems that prevent these devices from being widely used have to be overcome. The most significant problem is the involuntary amplitude variation of the sEMG signals due to the movement of electrodes during forearm motion. Moreover, for patients who have had a stroke or another neurological disease, the muscle activity of the impaired hand is weak and has a low signal-to-noise ratio (SNR). Thus, muscle activity detection methods intended for controlling robotic hand devices should not depend mainly on the amplitude characteristics of the sEMG signal in the detection process, and they need to be more reliable for sEMG signals that have a low SNR. Since amplitude-independent muscle activity detection methods meet these requirements, this paper investigates the performance of such a method on people who have had a stroke in terms of the detection of weak muscle activity and resistance to false alarms caused by the involuntary amplitude variation of sEMG signals; these two parameters are very important for achieving the reliable control of robotic hand devices intended for people with disabilities. A comparison between the performance of an amplitude-independent muscle activity detection algorithm and three amplitude-dependent algorithms was conducted by using sEMG signals recorded from six hemiparesis stroke survivors and from six healthy subjects. The results showed that the amplitude-independent algorithm performed better in terms of detecting weak muscle activity and resisting false alarms.
    Matched MeSH terms: Signal-To-Noise Ratio
  4. Katiri R, Hall DA, Buggy N, Hogan N, Horobin A, van de Heyning P, et al.
    Trials, 2020 Mar 04;21(1):238.
    PMID: 32131880 DOI: 10.1186/s13063-020-4094-9
    BACKGROUND: Single-sided deafness (SSD) describes the presence of a unilateral severe to profound sensorineural hearing loss. SSD disrupts spatial hearing and understanding speech in background noise. It has functional, psychological and social consequences. Potential options for rehabilitation include hearing aids and auditory implants. Benefits and harms of these interventions are documented inconsistently in the literature, using a variety of outcomes ranging from tests of speech perception to quality of life questionnaires. It is therefore difficult to compare interventions when rehabilitating SSD. The Core Rehabilitation Outcome Set for Single Sided Deafness (CROSSSD) study is an international initiative that aims to develop a minimum set of core outcomes for use in future trials of SSD interventions.

    METHODS/DESIGN: The CROSSSD study adopts an international two-round online modified Delphi survey followed by a stakeholder consensus meeting to identify a patient-centred core outcome domain set for SSD based on what is considered critical and important for assessing whether an intervention for SSD has worked.

    DISCUSSION: The resulting core outcome domain set will act as a minimum standard for reporting in future clinical trials and could have further applications in guiding the use of outcome measures in clinical practice. Standardisation will facilitate comparison of research findings.

    Matched MeSH terms: Noise
  5. Quar TK, Ching TY, Newall P, Sharma M
    Int J Audiol, 2013 May;52(5):322-32.
    PMID: 23570290 DOI: 10.3109/14992027.2012.755740
    The study aims to compare the performance of hearing aids fitted according to the NAL-NL1 and DSL v5 prescriptive procedure for children.
    Matched MeSH terms: Noise/adverse effects
  6. Ibrahim IA, Ting HN, Moghavvemi M
    J Int Adv Otol, 2019 Apr;15(1):87-93.
    PMID: 30924771 DOI: 10.5152/iao.2019.4553
    OBJECTIVES: This study uses a new approach for classifying the human ethnicity according to the auditory brain responses (electroencephalography [EEG] signals) with a high level of accuracy. Moreover, the study presents three different algorithms used to classify the human ethnicity using auditory brain responses. The algorithms were tested on Malays and Chinese as a case study.

    MATERIALS AND METHODS: The EEG signal was used as a brain response signal, which was evoked by two auditory stimuli (Tones and Consonant Vowels stimulus). The study was carried out on Malaysians (Malay and Chinese) with normal hearing and with hearing loss. A ranking process for the subjects' EEG data and the nonlinear features was used to obtain the maximum classification accuracy.

    RESULTS: The study formulated the classification of Normal Hearing Ethnicity Index and Sensorineural Hearing Loss Ethnicity Index. These indices classified the human ethnicity according to brain auditory responses by using numerical values of response signal features. Three classification algorithms were used to verify the human ethnicity. Support Vector Machine (SVM) classified the human ethnicity with an accuracy of 90% in the cases of normal hearing and sensorineural hearing loss (SNHL); the SVM classified with an accuracy of 84%.

    CONCLUSION: The classification indices categorized or separated the human ethnicity in both hearing cases of normal hearing and SNHL with high accuracy. The SVM classifier provided a good accuracy in the classification of the auditory brain responses. The proposed indices might constitute valuable tools for the classification of the brain responses according to the human ethnicity.

    Matched MeSH terms: Noise/adverse effects
  7. Safara F, Doraisamy S, Azman A, Jantan A, Abdullah Ramaiah AR
    Comput Biol Med, 2013 Oct;43(10):1407-14.
    PMID: 24034732 DOI: 10.1016/j.compbiomed.2013.06.016
    Wavelet packet transform decomposes a signal into a set of orthonormal bases (nodes) and provides opportunities to select an appropriate set of these bases for feature extraction. In this paper, multi-level basis selection (MLBS) is proposed to preserve the most informative bases of a wavelet packet decomposition tree through removing less informative bases by applying three exclusion criteria: frequency range, noise frequency, and energy threshold. MLBS achieved an accuracy of 97.56% for classifying normal heart sound, aortic stenosis, mitral regurgitation, and aortic regurgitation. MLBS is a promising basis selection to be suggested for signals with a small range of frequencies.
    Matched MeSH terms: Signal-To-Noise Ratio
  8. Liew SC, Liew SW, Zain JM
    J Digit Imaging, 2013 Apr;26(2):316-25.
    PMID: 22555905 DOI: 10.1007/s10278-012-9484-4
    Tamper localization and recovery watermarking scheme can be used to detect manipulation and recover tampered images. In this paper, a tamper localization and lossless recovery scheme that used region of interest (ROI) segmentation and multilevel authentication was proposed. The watermarked images had a high average peak signal-to-noise ratio of 48.7 dB and the results showed that tampering was successfully localized and tampered area was exactly recovered. The usage of ROI segmentation and multilevel authentication had significantly reduced the time taken by approximately 50 % for the tamper localization and recovery processing.
    Matched MeSH terms: Signal-To-Noise Ratio
  9. Salleh SH, Hussain HS, Swee TT, Ting CM, Noor AM, Pipatsart S, et al.
    Int J Nanomedicine, 2012;7:2873-81.
    PMID: 22745550 DOI: 10.2147/IJN.S32315
    Auscultation of the heart is accompanied by both electrical activity and sound. Heart auscultation provides clues to diagnose many cardiac abnormalities. Unfortunately, detection of relevant symptoms and diagnosis based on heart sound through a stethoscope is difficult. The reason GPs find this difficult is that the heart sounds are of short duration and separated from one another by less than 30 ms. In addition, the cost of false positives constitutes wasted time and emotional anxiety for both patient and GP. Many heart diseases cause changes in heart sound, waveform, and additional murmurs before other signs and symptoms appear. Heart-sound auscultation is the primary test conducted by GPs. These sounds are generated primarily by turbulent flow of blood in the heart. Analysis of heart sounds requires a quiet environment with minimum ambient noise. In order to address such issues, the technique of denoising and estimating the biomedical heart signal is proposed in this investigation. Normally, the performance of the filter naturally depends on prior information related to the statistical properties of the signal and the background noise. This paper proposes Kalman filtering for denoising statistical heart sound. The cycles of heart sounds are certain to follow first-order Gauss-Markov process. These cycles are observed with additional noise for the given measurement. The model is formulated into state-space form to enable use of a Kalman filter to estimate the clean cycles of heart sounds. The estimates obtained by Kalman filtering are optimal in mean squared sense.
    Matched MeSH terms: Signal-To-Noise Ratio
  10. Mukari SZ, Mamat WH
    Audiol. Neurootol., 2008;13(5):328-34.
    PMID: 18460868 DOI: 10.1159/000128978
    The purposes of this study were to: (1) compare medial olivocochlear system (MOCS) functioning and speech perception in noise in young and older adults and (2) to quantify the correlation between MOCS functioning and speech perception in noise. Measurements were taken in 20 young (mean 26.3 +/- 2.1 years) and 20 older adults (mean 55.2 +/- 2.8 years). Contralateral distortion product otoacoustic emission (DPOAE) suppression was measured to assess MOCS functioning. Speech perception in noise was evaluated using the Hearing in Noise Test in noise-ipsilateral, noise-front and noise-contralateral test conditions. The results revealed that the older group had a significantly lower high-frequency (3-8 kHz) contralateral DPOAE suppression, and performed more poorly in the noise-ipsilateral condition than the younger group. However, there was no correlation between contralateral DPOAE suppression and speech perception in noise. This study suggests that poor speech perception performance in noise experienced by older adults might be due to a decline in medial olivocochlear functioning, among other factors.
    Matched MeSH terms: Noise
  11. Ting CM, Samdin SB, Salleh ShH, Omar MH, Kamarulafizam I
    PMID: 23367426 DOI: 10.1109/EMBC.2012.6347491
    This paper applies an expectation-maximization (EM) based Kalman smoother (KS) approach for single-trial event-related potential (ERP) estimation. Existing studies assume a Markov diffusion process for the dynamics of ERP parameters which is recursively estimated by optimal filtering approaches such as Kalman filter (KF). However, these studies only consider estimation of ERP state parameters while the model parameters are pre-specified using manual tuning, which is time-consuming for practical usage besides giving suboptimal estimates. We extend the KF approach by adding EM based maximum likelihood estimation of the model parameters to obtain more accurate ERP estimates automatically. We also introduce different model variants by allowing flexibility in the covariance structure of model noises. Optimal model selection is performed based on Akaike Information Criterion (AIC). The method is applied to estimation of chirp-evoked auditory brainstem responses (ABRs) for detection of wave V critical for assessment of hearing loss. Results shows that use of more complex covariances are better estimating inter-trial variability.
    Matched MeSH terms: Signal-To-Noise Ratio
  12. Chow LS, Rajagopal H, Paramesran R, Alzheimer's Disease Neuroimaging Initiative
    Magn Reson Imaging, 2016 07;34(6):820-831.
    PMID: 26969762 DOI: 10.1016/j.mri.2016.03.006
    Medical Image Quality Assessment (IQA) plays an important role in assisting and evaluating the development of any new hardware, imaging sequences, pre-processing or post-processing algorithms. We have performed a quantitative analysis of the correlation between subjective and objective Full Reference - IQA (FR-IQA) on Magnetic Resonance (MR) images of the human brain, spine, knee and abdomen. We have created a MR image database that consists of 25 original reference images and 750 distorted images. The reference images were distorted with six types of distortions: Rician Noise, Gaussian White Noise, Gaussian Blur, DCT compression, JPEG compression and JPEG2000 compression, at various levels of distortion. Twenty eight subjects were chosen to evaluate the images resulting in a total of 21,700 human evaluations. The raw scores were then converted to Difference Mean Opinion Score (DMOS). Thirteen objective FR-IQA metrics were used to determine the validity of the subjective DMOS. The results indicate a high correlation between the subjective and objective assessment of the MR images. The Noise Quality Measurement (NQM) has the highest correlation with DMOS, where the mean Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are 0.936 and 0.938 respectively. The Universal Quality Index (UQI) has the lowest correlation with DMOS, where the mean PLCC and SROCC are 0.807 and 0.815 respectively. Student's T-test was used to find the difference in performance of FR-IQA across different types of distortion. The superior IQAs tested statistically are UQI for Rician noise images, Visual Information Fidelity (VIF) for Gaussian blur images, NQM for both DCT and JPEG compressed images, Peak Signal-to-Noise Ratio (PSNR) for JPEG2000 compressed images.
    Matched MeSH terms: Signal-To-Noise Ratio
  13. Sen RN, Yeow PH
    Int J Occup Saf Ergon, 2003;9(1):57-74.
    PMID: 12636892
    The study aimed at reducing the occupational health and safety problems faced by the manual component insertion operators. Subjective and objective assessments, and direct observations were made in the printed circuit assembly factory. Simple and low-cost ergonomic interventions were implemented, that is, repairing chairs, reducing high workloads, assigning operators to a maximum of 2 workstations, confining machines that emitted bad smell and much noise, and providing finger work aids. The results of the interventions were reductions in operators' work discomforts, that is, chair discomfort (by 90%), high work stress, and discomfort due to profound change in their workstations. Their health hazards were also eliminated, that is, inhalation of toxic fumes, exposure to too much noise, and pain due to pressing sharp components.
    Matched MeSH terms: Noise, Occupational
  14. Irniza Rasdi, Noraini Mohd Zin, Sharifah Norkhadijah Syed Ismail
    MyJurnal
    Introduction: Noise was evident to reduce job satisfaction among workers which will negative impacts to workers including increase job turnover, decrease motivation and increased number of accidents. This study aims to explore job satisfaction and its risk factors among workers working in a noisy workplace. Method: The study design was cross-sectional study which involved 167 workers in a cable manufacturing factory selected by simple random sam- pling. MSQ was used to assess employee’s satisfaction with their job on seven facets and sound level meter was used to measure workplace noise level. Results: All respondents were exposed to noise above permissible exposure limit. Most workers (49%) were moderately satisfied with their work. Factors that were rated as lowest level of satisfaction were work itself (the ability to work alone) (40%) and the way company system policies are implemented (40%). Factors with the highest level of satisfaction were their freedom to implement their judgement (responsibility) (51%) and the supervision quality of their superiors (51%). The most dominant facet predicting total satisfaction level was recognition followed by advancement and company policy and administration. All variables in socio-demographical and job characteristics were not significantly associated with their level of job satisfaction except noise. Noise was significant in predicting one facet of job satisfaction which was physical work condition. Conclusion: Overall, the average level of job satisfaction among respondents were moderate and they were exposed to occupational noise which was the only significant study variable correlated with their job satisfaction.
    Matched MeSH terms: Noise, Occupational
  15. Abdullah KA, McEntee MF, Reed WM, Kench PL
    J Appl Clin Med Phys, 2020 Sep;21(9):209-214.
    PMID: 32657493 DOI: 10.1002/acm2.12977
    PURPOSE: The purpose of this study was to investigate the effect of increasing iterative reconstruction (IR) algorithm strength at different tube voltages in coronary computed tomography angiography (CCTA) protocols using a three-dimensional (3D)-printed and Catphan® 500 phantoms.

    METHODS: A 3D-printed cardiac insert and Catphan 500 phantoms were scanned using CCTA protocols at 120 and 100 kVp tube voltages. All CT acquisitions were reconstructed using filtered back projection (FBP) and Adaptive Statistical Iterative Reconstruction (ASIR) algorithm at 40% and 60% strengths. Image quality characteristics such as image noise, signal-noise ratio (SNR), contrast-noise ratio (CNR), high spatial resolution, and low contrast resolution were analyzed.

    RESULTS: There was no significant difference (P > 0.05) between 120 and 100 kVp measures for image noise for FBP vs ASIR 60% (16.6 ± 3.8 vs 16.7 ± 4.8), SNR of ASIR 40% vs ASIR 60% (27.3 ± 5.4 vs 26.4 ± 4.8), and CNR of FBP vs ASIR 40% (31.3 ± 3.9 vs 30.1 ± 4.3), respectively. Based on the Modulation Transfer Function (MTF) analysis, there was a minimal change of image quality for each tube voltage but increases when higher strengths of ASIR were used. The best measure of low contrast detectability was observed at ASIR 60% at 120 kVp.

    CONCLUSIONS: Changing the IR strength has yielded different image quality noise characteristics. In this study, the use of 100 kVp and ASIR 60% yielded comparable image quality noise characteristics to the standard CCTA protocols using 120 kVp of ASIR 40%. A combination of 3D-printed and Catphan® 500 phantoms could be used to perform CT dose optimization protocols.

    Matched MeSH terms: Signal-To-Noise Ratio
  16. Mohammad Azmi HH, Goh BS, Abdullah A, Umat C
    Acta Otolaryngol, 2020 Oct;140(10):838-844.
    PMID: 32564640 DOI: 10.1080/00016489.2020.1775887
    INTRODUCTION: Bilateral cochlear implants are seen to improve hearing capabilities.

    OBJECTIVE: To assess the auditory outcome of paediatric bilateral cochlear implant in Universiti Kebangsaan Malaysia.

    MATERIALS AND METHODS: This was a cross-sectional and descriptive study single centre analysis. Categories of Auditory Performance (CAP-II) scale and Speech, Spatial and Qualities (SSQ) of Hearing questionnaire were used.

    RESULTS: Forty-six patients were recruited. Majority of the children (30.4%) rated 7 and 23.9% scored perfectly (9) based on the CAP-II Scale. The least performing children were rated 5 (average). Children that were implanted sequentially within 24 months showed median CAP-II scale of 7. No significant correlation seen between CAP-II and the duration interval, use and age of 1st CI (p > .05). The speech domain of SSQ-P scale showed median value of 8 indicating good speech understanding. The spatial hearing domain had median value of 7, quality of hearing domain had median of 8. Significant correlation seen in hearing in noise with the duration of use of CI (p 

    Matched MeSH terms: Noise
  17. Foo LS, Yap WS, Hum YC, Manan HA, Tee YK
    J Magn Reson, 2020 01;310:106648.
    PMID: 31760147 DOI: 10.1016/j.jmr.2019.106648
    Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) holds great potential to provide new metabolic information for clinical applications such as tumor, stroke and Parkinson's Disease diagnosis. Many active research and developments have been conducted to translate this emerging MRI technique for routine clinical applications. In general, there are two CEST quantification techniques: (i) model-free and (ii) model-based techniques. The reliability of these quantification techniques depends heavily on the experimental conditions and quality of the collected data. Errors such as noise may lead to misleading quantification results and thus inaccurate diagnosis when CEST imaging becomes a standard or routine imaging scan in the future. This paper investigates the accuracy and robustness of these quantification techniques under different signal-to-noise (SNR) levels and magnetic field strengths. The quantified CEST effect before and after adding random Gaussian White Noise using model-free and model-based quantification techniques were compared. It was found that the model-free technique consistently yielded larger average percentage error across all tested parameters compared to its model-based counterpart, and that the model-based technique could withstand SNR of about 3 times lower than the model-free technique. When applied on noisy brain tumor, ischemic stroke, and Parkinson's Disease clinical data, the model-free technique failed to produce significant differences between normal and abnormal tissue whereas the model-based technique consistently generated significant differences. Although the model-free technique was less accurate and robust, its simplicity and thus speed would still make it a good approximate when the SNR was high (>50) or when the CEST effect was large and well-defined. For more accurate CEST quantification, model-based techniques should be considered. When SNR was low (<50) and the CEST effect was small such as those acquired from clinical field strength scanners, which are generally 3T and below, model-based techniques should be considered over model-free counterpart to maintain an average percentage error of less than 44% even under very noisy condition as tested in this work.
    Matched MeSH terms: Signal-To-Noise Ratio
  18. Al-Qazzaz NK, Hamid Bin Mohd Ali S, Ahmad SA, Islam MS, Escudero J
    Sensors (Basel), 2017 Jun 08;17(6).
    PMID: 28594352 DOI: 10.3390/s17061326
    Characterizing dementia is a global challenge in supporting personalized health care. The electroencephalogram (EEG) is a promising tool to support the diagnosis and evaluation of abnormalities in the human brain. The EEG sensors record the brain activity directly with excellent time resolution. In this study, EEG sensor with 19 electrodes were used to test the background activities of the brains of five vascular dementia (VaD), 15 stroke-related patients with mild cognitive impairment (MCI), and 15 healthy subjects during a working memory (WM) task. The objective of this study is twofold. First, it aims to enhance the recorded EEG signals using a novel technique that combines automatic independent component analysis (AICA) and wavelet transform (WT), that is, the AICA-WT technique; second, it aims to extract and investigate the spectral features that characterize the post-stroke dementia patients compared to the control subjects. The proposed AICA-WT technique is a four-stage approach. In the first stage, the independent components (ICs) were estimated. In the second stage, three-step artifact identification metrics were applied to detect the artifactual components. The components identified as artifacts were marked as critical and denoised through DWT in the third stage. In the fourth stage, the corrected ICs were reconstructed to obtain artifact-free EEG signals. The performance of the proposed AICA-WT technique was compared with those of two other techniques based on AICA and WT denoising methods using cross-correlation X C o r r and peak signal to noise ratio ( P S N R ) (ANOVA, p ˂ 0.05). The AICA-WT technique exhibited the best artifact removal performance. The assumption that there would be a deceleration of EEG dominant frequencies in VaD and MCI patients compared with control subjects was assessed with AICA-WT (ANOVA, p ˂ 0.05). Therefore, this study may provide information on post-stroke dementia particularly VaD and stroke-related MCI patients through spectral analysis of EEG background activities that can help to provide useful diagnostic indexes by using EEG signal processing.
    Matched MeSH terms: Signal-To-Noise Ratio
  19. Othman E, Yusoff AN, Mohamad M, Abdul Manan H, Abd Hamid AI, Giampietro V
    Exp Brain Res, 2020 Apr;238(4):945-956.
    PMID: 32179941 DOI: 10.1007/s00221-020-05765-3
    The present study examined the impact of white noise on word recall performance and brain activity in 40 healthy adolescents, split in two groups (normal and low) depending on their auditory working memory capacity (AWMC). Using functional magnetic resonance imaging, participants performed a backward recall task under four different signal-to-noise ratio (SNR) conditions: 15, 10, 5, and 0-dB SNR. Behaviorally, normal AWMC individuals scored significantly higher than low AWMC individuals across noise levels. Whole-brain analyses showed brain activation not to be statistically different between groups across noise levels. In the normal group, a significant positive relationship was found between performance and number of activated voxels in the right superior frontal gyrus. In the low group, significant positive correlations were found between performance and number of activated voxels in left superior frontal gyrus, left inferior frontal gyrus, and left anterior cingulate cortex. These findings suggest that the strategic structure involved in the enhancement of AWM performance may differ in normal and low AWMC individuals.
    Matched MeSH terms: Noise
  20. Wan Ismail WZ, Sim KS, Tso CP, Ting HY
    Scanning, 2011 Jul-Aug;33(4):233-51.
    PMID: 21611953 DOI: 10.1002/sca.20237
    To reduce undesirable charging effects in scanning electron microscope images, Rayleigh contrast stretching is developed and employed. First, re-scaling is performed on the input image histograms with Rayleigh algorithm. Then, contrast stretching or contrast adjustment is implemented to improve the images while reducing the contrast charging artifacts. This technique has been compared to some existing histogram equalization (HE) extension techniques: recursive sub-image HE, contrast stretching dynamic HE, multipeak HE and recursive mean separate HE. Other post processing methods, such as wavelet approach, spatial filtering, and exponential contrast stretching, are compared as well. Overall, the proposed method produces better image compensation in reducing charging artifacts.
    Matched MeSH terms: Signal-To-Noise Ratio
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