Displaying publications 1 - 20 of 78 in total

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  1. Chordodes combiareolatus, a new species of horsehair worms (Nematomorpha) from Nagaland, India, with further comments on Chordodes moutoni
    Schmidt-Rhaesa A, Limatemjen L, Yadav AK
    Zootaxa, 2015;3925(1):202-10.
    PMID: 25781739 DOI: 10.11646/zootaxa.3925.2.3
    The currently known diversity of horsehair worms (Nematomorpha) from India is only 17 species. We report here two female specimens found on two occasions on a terrace paddy field in Tsupo, Viswema, Kohima, Nagaland, India. Although found at the same location, both species differ in their cuticular structures. One is determined as Chordodes moutoni, a species known from China, Malaysia and India. The other specimen shows a new type of cuticular structure, the areoles, which combines characters of both simple areoles and tubercle areoles. This specimen is described as a new species, C. combiareolatus. Both specimens show arrangements on the cuticle, in which a circle of areoles surrounds a region of "naked" cuticle. We interpret these regions as artifacts caused by the breaking off of the central crowned areoles, leaving only the circumcluster areoles behind.
    Matched MeSH terms: Artifacts
  2. Fulltext Fly artifact documentation of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) - a forensically important blowfly species in Malaysia
    Zuha RM, Supriyani M, Omar B
    Trop Biomed, 2008 Apr;25(1):17-22.
    PMID: 18600200
    Analysis on fly artifacts produced by forensically important blowfly, Chrysomya megacephala (Fabricius) (Diptera:Calliphoridae), revealed several unique patterns. They can be divided into fecal spots, regurgitation spots and swiping stains. The characteristics of fecal spots are round with three distinct levels of pigmentation; creamy, brownish and darkly pigmented. Matrix of the spots appears cloudy. The round spots are symmetrical and non-symmetrical, delineated by irregular and darker perimeter which only visible in fairly colored fecal spots. Diameter of these artifacts ranged from 0.5 mm to 4 mm. Vomit or regurgitation spots are determined by the presence of craters due to sucking activity of blowflies and surrounded by thickly raised and darker colored perimeter. The size of these specks ranged from 1 mm to 2 mm. Matrix of the spots displays irregular surface and reflective under auxiliary microscope light. Swiping stains due to defecation by flies consists of two distinguishable segments, the body and tail. It can be seen as a tear drop-like, sperm-like, snake-like and irregular tadpole-like stain. The direction of body and tail is inconsistent and length ranged between 4.8 mm to 9.2 mm. A finding that should be highlighted in this observation is the presence of crater on tadpole-like swiping stain which is apparent by its raised border characteristic and reflective under auxiliary microscope light. The directionality of this darkly brown stain is random. This unique mix of regurgitation and swiping stain has never been reported before. Highlighting the features of artifacts produced by flies would hopefully add our understanding in differentiating them from blood spatters produced from victims at crime scenes.
    Matched MeSH terms: Artifacts*
  3. Fulltext Cardiac A-lines in fast scan as a sign of pneumopericardium
    Md Noor J, Eddie EA
    Ultrasound J, 2019 Apr 25;11(1):7.
    PMID: 31359168 DOI: 10.1186/s13089-019-0123-x
    BACKGROUND: Traumatic pneumopericardium is rare and usually results from blunt injury. Diagnosis through clinical and chest X-ray is often difficult. Ultrasound findings of A-line artifacts in the cardiac window may suggest pneumopericardium.

    CASE PRESENTATION: A young man involved in a car accident and sustained blunt thoracic injuries, among others. As part of primary survey, FAST scan was performed. Subxiphoid view to look for evidence of pericardial effusion showed part of the cardiac image obscured by A-lines. Other cardiac windows showed only A-lines, as well. A suspicion of pneumopericardium was raised and CT scan confirmed the diagnosis.

    CONCLUSIONS: Although FAST scan was originally used to look for presence of free fluid, with the knowledge of lung ultrasound for pneumothorax, our findings suggest that FAST scan can also be used to detect pneumopericardium.

    Matched MeSH terms: Artifacts
  4. Speciation patterns of heavy metals in tropical estuarine anoxic and oxidized sediments by different sequential extraction schemes
    Ngiam LS, Lim PE
    Sci Total Environ, 2001 Jul 25;275(1-3):53-61.
    PMID: 11482403
    The speciation patterns of Cu, Cd, Zn, Pb, Fe and Mn in sediment samples under anoxic and oxidized conditions were investigated using three-stage, four-stage and five-stage sequential extraction schemes. All the extraction schemes identify the non-residual metal among three basic operationally-defined host fractions, namely, exchangeable, reducible and organic/sulfide bound. The anoxic sediment samples were found to have been oxidized during the extraction stage for the reducible fraction under the three-stage and four-stage schemes and the moderately reducible fraction under the five-stage scheme despite the maintenance of an oxygen-free environment. This artifact has resulted in an over-representation of the reducible fraction and an under-representation of the organic/sulfide fraction in the heavy metal speciation patterns of anoxic sediment samples. For Cd, Zn and Pb which had > 70% associated with the acid volatile sulfide in the organic/sulfide fraction, this artifact has resulted in the observation of a decrease in the reducible fraction and, in some cases, an increase in the organic/sulfide fraction upon oxidation of the anoxic sediment samples.
    Matched MeSH terms: Artifacts
  5. Fulltext A case study on culture-oriented design preferences
    Wardahanisah Razali, Rusmadiah Anwar
    The Pertanika Journal of Scholarly Research Reviews, 2018;4(2):64-70.
    MyJurnal
    It is hard to identify the local Malay identity in a design context compared to other cultural oriented design in several countries. This paper tries to uncover how designers interpret local identity embodied agent based on local items influences and understood and the influence of incremental, radical design that changes respective to preceding designs. A descriptive study through the literature reviews focusses on a type of artefact initiated through cultural-oriented design. Based on the preliminary study, a sampling taken from the Chinese, Indian, Japanese or European consistently apply the same fundamental understanding in regards to the culture-oriented design. From the same point of view, teapot seems to be used as one of the dominant artefact indicating the design preferences. This research will benefit both the academia and the industry and identify significant identity based on the local context and become an embodied agent to give impact in establishing the state-of-the-art of brand, the identity of local design, establish new trademark towards generating domestic, international economy and promote the nation worldwide throughout design platform.
    Matched MeSH terms: Artifacts
  6. Comparison study of the MRI shoulder PROPELLER technique with differential image quality by variation of shoulder coils
    Khairi M, Zakaria F, Supar R, Mohd Z
    Med J Malaysia, 2024 Mar;79(Suppl 1):74-81.
    PMID: 38555889
    INTRODUCTION: Motion and pulsation artifacts are the most prominent types of artifacts in Magnetic Resonance Imaging (MRI) of the shoulder. Therefore, this study examined the Periodically Rotating Overlapping Parallel Lines with Enhanced Reconstruction (PROPELLER) technique with small flex coil (SFC) and dedicated shoulder coil (DSC) for the reduction of motion and pulsation artifacts. The signalto- noise ratio (SNR) and contrast-to-noise ratio (CNR) of the standard proton density fat saturation (PDFS) pulse sequence and the PROPELLER proton density fat saturation (PROPELLER PDFS) pulse sequence were also evaluated.

    MATERIALS AND METHODS: Eighteen (18) participants who met the inclusion and exclusion criteria were scanned using a standard non-contrast MRI shoulder protocol including the PDFS pulse sequence and the PROPELLER PDFS pulse sequence using a small flex coil and a dedicated shoulder coil. Two experienced musculoskeletal (MSK) radiologists evaluated and graded the presence of artifacts on the MR images and the SNR and CNR were measured quantitatively.

    RESULTS: The non-parametric Wilcoxon Signed Rank test revealed a significant reduction in motion and pulsation artifacts between the PROPELLER PDFS pulse sequence and the standard PDFS pulse sequence. In addition, the nonparametric Mann-Whitney U test revealed that the mean rank of SNR for the standard sequence was statistically significant when compared to the PROPELLER sequence for both coil types. The CNR of the PROPELLER sequence was statistically significant between fat-fluid, bone-fluid, bonetendon, bone-muscle, and muscle-fluid when using SFC and DSC.

    CONCLUSION: This study proved that the PROPELLER-PDFS pulse sequence effectively eliminates motion and pulsation artifacts, regardless of the coils utilised. The PROPELLERPDFS pulse sequence can therefore be implemented into the standard MRI shoulder procedure.

    Matched MeSH terms: Artifacts
  7. Microwave-stimulated formaldehyde fixation of experimental renal biopsy tissues: computerised morphometric analysis of distortion artefacts
    Looi LM, Loh KC
    Malays J Pathol, 2005 Jun;27(1):23-7.
    PMID: 16676689
    Although microwave irradiation has been used in the histopathology laboratory for several years, there has been minimal published experimental data on its effects on the technical and staining quality of histological sections. Furthermore, it has not been clear whether the advantages gained in reduction of fixation and staining duration has been at the expense of increasing architectural distortion to the tissues. We report here our experience with computerised morphometric analysis to investigate glomerular artifacts caused by microwave-stimulated fixation of renal tissues. 39 rat and 33 human autopsy kidney samples were subjected to (1) fixation in neutral buffered formaldehyde (control), (2) microwave-stimulated fixation followed by neutral buffered formaldehyde, and (3) neutral buffered formaldehyde followed by microwave irradiation. In addition, the effect of post-fixation in 70% ethanol was also investigated. Microwave irradiation was delivered through a dedicated laboratory microwave oven at 80% power and at 55 degrees C for 3 minutes. The different fixation methods were compared with regards to shrinkage (distortion) to glomerular structures (glomeruli and Bowman's spaces) on H and E sections, as determined by morphometric image analysis using a temporary assembled-system consisting of a trinocular microscope, a digital video camera and personal computer. A FlashPoint VGA 3.3 film-grabber card was used to capture images for morphometric analysis by using a Scion Image program. Morphometric analysis of glomerular structures showed that microwaves caused more shrinkage to the area bounded by the Bowman's capsule than the glomerulus proper, but post-fixation with ethanol reduced this shrinkage. These findings have implications on the logistics of tissue preparation of renal biopsies in clinical practice.
    Matched MeSH terms: Artifacts
  8. Fulltext The resin-embedded cornea prepared via rapid processing protocol : a good histomorphometric target for clinical investigation in ophthalmology and optometry
    Cheah PS, Mohidin N, Mohd Ali B, Maung M, Latif AA
    Malays J Med Sci, 2008 Jul;15(3):49-54.
    PMID: 22570589
    This study illustrates and quantifies the changes on corneal tissue between the paraffin-embedded and resin-embedded blocks and thus, selects a better target in investigational ophthalmology and optometry via light microscopy. Corneas of two cynomolgus monkeys (Macaca fascicularis) were used in this study. The formalin-fixed cornea was prepared in paraffin block via the conventional tissue processing protocol (4-day protocol) and stained with haematoxylin and eosin. The glutaraldehyde-fixed cornea was prepared in resin block via the rapid and modified tissue processing procedure (1.2-day protocol) and stained with toluidine blue. The paraffin-embedded sample exhibits various undesired tissue damage and artifact such as thinner epithelium (due to the substantial volumic extraction from the tissue), thicker stroma layer (due to the separation of lamellae and the presence of voids) and the distorted endothelium. In contrast, the resin-embedded corneal tissue has demonstrated satisfactory corneal ultrastructural preservation. The rapid and modified tissue processing method for preparing the resin-embedded is particularly beneficial to accelerate the microscopic evaluation in ophthalmology and optometry.
    Matched MeSH terms: Artifacts
  9. Fulltext Using 21st-Century Technologies to Determine the Cognitive Capabilities of a 11,000-Year-Old Perak Man Who Had Brachymesophalangia Type A2
    Abdullah JY, Saidin M, Rajion ZA, Hadi H, Mohamad N, Moraes C, et al.
    Malays J Med Sci, 2021 Feb;28(1):1-8.
    PMID: 33679214 DOI: 10.21315/mjms2021.28.1.1
    Perak Man, named after the state where the skeleton was found, was the most complete skeleton found in Southeast Asia. The funerary artefacts indicate that Perak Man was highly respected, as he was buried at the centre of the highest cave in Lenggong, and he was the only person buried there. A copy of the original skull was made using computed tomography (CT) and 3D printing. Based on the internal structure of the reconstructed skull, the estimated intracranial volume (ICV) is 1,204.91 mL. The hypothetical face of Perak Man was reconstructed according to established forensic methods. Based on his presumed status, Perak Man was likely a respected person in the group and, perhaps, a shaman and the most knowledgeable person in the group regarding survival, hunting, gathering and other aspects of Palaeolithic daily life.
    Matched MeSH terms: Artifacts
  10. Fulltext Limited Evaluation of Image Quality Produced by a Portable Head CT Scanner (CereTom) in a Neurosurgery Centre
    Abdullah AC, Adnan JS, Rahman NA, Palur R
    Malays J Med Sci, 2017 Mar;24(1):104-112.
    PMID: 28381933 DOI: 10.21315/mjms2017.24.1.11
    INTRODUCTION: Computed tomography (CT) is the preferred diagnostic toolkit for head and brain imaging of head injury. A recent development is the invention of a portable CT scanner that can be beneficial from a clinical point of view.

    AIM: To compare the quality of CT brain images produced by a fixed CT scanner and a portable CT scanner (CereTom).

    METHODS: This work was a single-centre retrospective study of CT brain images from 112 neurosurgical patients. Hounsfield units (HUs) of the images from CereTom were measured for air, water and bone. Three assessors independently evaluated the images from the fixed CT scanner and CereTom. Streak artefacts, visualisation of lesions and grey-white matter differentiation were evaluated at three different levels (centrum semiovale, basal ganglia and middle cerebellar peduncles). Each evaluation was scored 1 (poor), 2 (average) or 3 (good) and summed up to form an ordinal reading of 3 to 9.

    RESULTS: HUs for air, water and bone from CereTom were within the recommended value by the American College of Radiology (ACR). Streak artefact evaluation scores for the fixed CT scanner was 8.54 versus 7.46 (Z = -5.67) for CereTom at the centrum semiovale, 8.38 (SD = 1.12) versus 7.32 (SD = 1.63) at the basal ganglia and 8.21 (SD = 1.30) versus 6.97 (SD = 2.77) at the middle cerebellar peduncles. Grey-white matter differentiation showed scores of 8.27 (SD = 1.04) versus 7.21 (SD = 1.41) at the centrum semiovale, 8.26 (SD = 1.07) versus 7.00 (SD = 1.47) at the basal ganglia and 8.38 (SD = 1.11) versus 6.74 (SD = 1.55) at the middle cerebellar peduncles. Visualisation of lesions showed scores of 8.86 versus 8.21 (Z = -4.24) at the centrum semiovale, 8.93 versus 8.18 (Z = -5.32) at the basal ganglia and 8.79 versus 8.06 (Z = -4.93) at the middle cerebellar peduncles. All results were significant with P-value < 0.01.

    CONCLUSIONS: Results of the study showed a significant difference in image quality produced by the fixed CT scanner and CereTom, with the latter being more inferior than the former. However, HUs of the images produced by CereTom do fulfil the recommendation of the ACR.

    Matched MeSH terms: Artifacts
  11. Automatic classification of regular and irregular capnogram segments using time- and frequency-domain features: A machine learning-based approach
    El-Badawy IM, Singh OP, Omar Z
    Technol Health Care, 2021;29(1):59-72.
    PMID: 32716337 DOI: 10.3233/THC-202198
    BACKGROUND: The quantitative features of a capnogram signal are important clinical metrics in assessing pulmonary function. However, these features should be quantified from the regular (artefact-free) segments of the capnogram waveform.

    OBJECTIVE: This paper presents a machine learning-based approach for the automatic classification of regular and irregular capnogram segments.

    METHODS: Herein, we proposed four time- and two frequency-domain features experimented with the support vector machine classifier through ten-fold cross-validation. MATLAB simulation was conducted on 100 regular and 100 irregular 15 s capnogram segments. Analysis of variance was performed to investigate the significance of the proposed features. Pearson's correlation was utilized to select the relatively most substantial ones, namely variance and the area under normalized magnitude spectrum. Classification performance, using these features, was evaluated against two feature sets in which either time- or frequency-domain features only were employed.

    RESULTS: Results showed a classification accuracy of 86.5%, which outperformed the other cases by an average of 5.5%. The achieved specificity, sensitivity, and precision were 84%, 89% and 86.51%, respectively. The average execution time for feature extraction and classification per segment is only 36 ms.

    CONCLUSION: The proposed approach can be integrated with capnography devices for real-time capnogram-based respiratory assessment. However, further research is recommended to enhance the classification performance.

    Matched MeSH terms: Artifacts
  12. Fulltext Advancements of data anomaly detection research in wireless sensor networks: a survey and open issues
    Rassam MA, Zainal A, Maarof MA
    Sensors (Basel), 2013;13(8):10087-122.
    PMID: 23966182 DOI: 10.3390/s130810087
    Wireless Sensor Networks (WSNs) are important and necessary platforms for the future as the concept "Internet of Things" has emerged lately. They are used for monitoring, tracking, or controlling of many applications in industry, health care, habitat, and military. However, the quality of data collected by sensor nodes is affected by anomalies that occur due to various reasons, such as node failures, reading errors, unusual events, and malicious attacks. Therefore, anomaly detection is a necessary process to ensure the quality of sensor data before it is utilized for making decisions. In this review, we present the challenges of anomaly detection in WSNs and state the requirements to design efficient and effective anomaly detection models. We then review the latest advancements of data anomaly detection research in WSNs and classify current detection approaches in five main classes based on the detection methods used to design these approaches. Varieties of the state-of-the-art models for each class are covered and their limitations are highlighted to provide ideas for potential future works. Furthermore, the reviewed approaches are compared and evaluated based on how well they meet the stated requirements. Finally, the general limitations of current approaches are mentioned and further research opportunities are suggested and discussed.
    Matched MeSH terms: Artifacts*
  13. Fulltext ARTYCUL: A Privacy-Preserving ML-Driven Framework to Determine the Popularity of a Cultural Exhibit on Display
    Tanwar G, Chauhan R, Yafi E
    Sensors (Basel), 2021 Feb 22;21(4).
    PMID: 33671822 DOI: 10.3390/s21041527
    We present ARTYCUL (ARTifact popularitY for CULtural heritage), a machine learning(ML)-based framework that graphically represents the footfall around an artifact on display at a museum or a heritage site. The driving factor of this framework was the fact that the presence of security cameras has become universal, including at sites of cultural heritage. ARTYCUL used the video streams of closed-circuit televisions (CCTV) cameras installed in such premises to detect human figures, and their coordinates with respect to the camera frames were used to visualize the density of visitors around the specific display items. Such a framework that can display the popularity of artifacts would aid the curators towards a more optimal organization. Moreover, it could also help to gauge if a certain display item were neglected due to incorrect placement. While items of similar interest can be placed in vicinity of each other, an online recommendation system may also use the reputation of an artifact to catch the eye of the visitors. Artificial intelligence-based solutions are well suited for analysis of internet of things (IoT) traffic due to the inherent veracity and volatile nature of the transmissions. The work done for the development of ARTYCUL provided a deeper insight into the avenues for applications of IoT technology to the cultural heritage domain, and suitability of ML to process real-time data at a fast pace. While we also observed common issues that hinder the utilization of IoT in the cultural domain, the proposed framework was designed keeping in mind the same obstacles and a preference for backward compatibility.
    Matched MeSH terms: Artifacts
  14. Fulltext Improved Reconstruction of MR Scanned Images by Using a Dictionary Learning Scheme
    Ikram S, Shah JA, Zubair S, Qureshi IM, Bilal M
    Sensors (Basel), 2019 Apr 23;19(8).
    PMID: 31018597 DOI: 10.3390/s19081918
    The application of compressed sensing (CS) to biomedical imaging is sensational since it permits a rationally accurate reconstruction of images by exploiting the image sparsity. The quality of CS reconstruction methods largely depends on the use of various sparsifying transforms, such as wavelets, curvelets or total variation (TV), to recover MR images. As per recently developed mathematical concepts of CS, the biomedical images with sparse representation can be recovered from randomly undersampled data, provided that an appropriate nonlinear recovery method is used. Due to high under-sampling, the reconstructed images have noise like artifacts because of aliasing. Reconstruction of images from CS involves two steps, one for dictionary learning and the other for sparse coding. In this novel framework, we choose Simultaneous code word optimization (SimCO) patch-based dictionary learning that updates the atoms simultaneously, whereas Focal underdetermined system solver (FOCUSS) is used for sparse representation because of a soft constraint on sparsity of an image. Combining SimCO and FOCUSS, we propose a new scheme called SiFo. Our proposed alternating reconstruction scheme learns the dictionary, uses it to eliminate aliasing and noise in one stage, and afterwards restores and fills in the k-space data in the second stage. Experiments were performed using different sampling schemes with noisy and noiseless cases of both phantom and real brain images. Based on various performance parameters, it has been shown that our designed technique outperforms the conventional techniques, like K-SVD with OMP, used in dictionary learning based MRI (DLMRI) reconstruction.
    Matched MeSH terms: Artifacts
  15. Fulltext Automatic Artifact Removal in EEG of Normal and Demented Individuals Using ICA-WT during Working Memory Tasks
    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: Artifacts
  16. Variants and pitfalls in MR imaging of knee injuries
    Tan HK, Bakri MM, Peh WC
    Semin Musculoskelet Radiol, 2014 Feb;18(1):45-53.
    PMID: 24515881 DOI: 10.1055/s-0034-1365834
    MR imaging is an established tool for the detection and diagnosis of various injuries and internal derangements of the knee, enabling excellent anatomical visualization and producing good soft tissue contrast and characterization. However, numerous normal variants and potential pitfalls may lead to diagnostic errors. Understanding the basic MR imaging principles, applying the correct technique, knowing the normal anatomy and variants, recognizing artifacts, and assuring good clinical and radiographic correlation helps avoid these potential pitfalls.
    Matched MeSH terms: Artifacts*
  17. Molecular Mitochondrial DNA and radiographic approaches for human archaeology identification
    Rus Dina Rus Din, Shahrul Hisham Zainal Ariffin, Sahidan Senafi, Rohaya Megat Abdul Wahab, Intan Zarina Zainol Abidin
    Sains Malaysiana, 2014;43:1523-1535.
    Ancient remains are considered very valuable artefacts, as they allow for the study of ancient cultures, phylogeny, evolution and the reconstruction of demographic history. To obtain all the information contained within remains, the investigation of such samples requires the expertise and various techniques from multiple fields of study. The present review focuses on the molecular biology and radiographic approaches used to identify ancient samples. Studies of ancient remains face various limitations; for example, the quality and quantity of the ancient samples can affect the difficulty of the investigations. Due to these limitations, new sophisticated techniques are being introduced to replace the earlier conventional techniques. A search was conducted using PubMed, Scopus, Science Direct and Science Finder to provide a new and timely review on the molecular mitochondrial DNA and radiographic analysis for human archaeology identification. The present review has determined that molecular biological approaches are very accurate and useful for the use in the ancestral determination of incomplete specimens, whereas observations of the dental pulp chamber are suitable for age at death estimations in both adults and children. However, these techniques are expensive and require expert personnel. Therefore, conventional approaches remain the favourite methods of most institutions, especially in Asia.
    Matched MeSH terms: Artifacts
  18. A review of common beam hardening correction methods for industrial x-ray computed tomography
    Ahmed O, Yushou Song
    Sains Malaysiana, 2018;47:1883-1890.
    X-ray computed tomography (XCT) became an important instrument for quality assurance in industry products as a
    non-destructive testing tool for inspection, evaluation, analysis and dimensional metrology. Thus, a high-quality image
    is required. Due to the polychromatic nature of X-ray energy in XCT, this leads to errors in attenuation coefficient
    which is generally known as beam hardening artifact. This leads to a distortion or blurring-like cupping and streak in
    the reconstruction images, where a significant decrease in imaging quality is observed. In this paper, recent research
    publications regarding common practical correction methods that were adopted to improve an imaging quality have been
    discussed. It was observed from the discussion and evaluation, that a problem behind beam hardening reduction for the
    multi-materials object, especially in the absence of prior information about X-ray spectrum and material characterizations
    would be a significant research contribution, if the correction could be achieved without the need to perform forward
    projections and multiple reconstructions.
    Matched MeSH terms: Artifacts
  19. Fulltext Astronomically calibrated 40Ar/39Ar age for the Toba supereruption and global synchronization of late Quaternary records
    Storey M, Roberts RG, Saidin M
    Proc Natl Acad Sci U S A, 2012 Nov 13;109(46):18684-8.
    PMID: 23112159 DOI: 10.1073/pnas.1208178109
    The Toba supereruption in Sumatra, ∼74 thousand years (ka) ago, was the largest terrestrial volcanic event of the Quaternary. Ash and sulfate aerosols were deposited in both hemispheres, forming a time-marker horizon that can be used to synchronize late Quaternary records globally. A precise numerical age for this event has proved elusive, with dating uncertainties larger than the millennial-scale climate cycles that characterized this period. We report an astronomically calibrated (40)Ar/(39)Ar age of 73.88 ± 0.32 ka (1σ, full external errors) for sanidine crystals extracted from Toba deposits in the Lenggong Valley, Malaysia, 350 km from the eruption source and 6 km from an archaeological site with stone artifacts buried by ash. If these artifacts were made by Homo sapiens, as has been suggested, then our age indicates that modern humans had reached Southeast Asia by ∼74 ka ago. Our (40)Ar/(39)Ar age is an order-of-magnitude more precise than previous estimates, resolving the timing of the eruption to the middle of the cold interval between Dansgaard-Oeschger events 20 and 19, when a peak in sulfate concentration occurred as registered by Greenland ice cores. This peak is followed by a ∼10 °C drop in the Greenland surface temperature over ∼150 y, revealing the possible climatic impact of the eruption. Our (40)Ar/(39)Ar age also provides a high-precision calibration point for other ice, marine, and terrestrial archives containing Toba sulfates and ash, facilitating their global synchronization at unprecedented resolution for a critical period in Earth and human history beyond the range of (14)C dating.
    Matched MeSH terms: Artifacts
  20. Fulltext Two-stage motion artefact reduction algorithm for electrocardiogram using weighted adaptive noise cancelling and recursive Hampel filter
    Ghaleb FA, Kamat MB, Salleh M, Rohani MF, Abd Razak S
    PLoS One, 2018;13(11):e0207176.
    PMID: 30457996 DOI: 10.1371/journal.pone.0207176
    The presence of motion artefacts in ECG signals can cause misleading interpretation of cardiovascular status. Recently, reducing the motion artefact from ECG signal has gained the interest of many researchers. Due to the overlapping nature of the motion artefact with the ECG signal, it is difficult to reduce motion artefact without distorting the original ECG signal. However, the application of an adaptive noise canceler has shown that it is effective in reducing motion artefacts if the appropriate noise reference that is correlated with the noise in the ECG signal is available. Unfortunately, the noise reference is not always correlated with motion artefact. Consequently, filtering with such a noise reference may lead to contaminating the ECG signal. In this paper, a two-stage filtering motion artefact reduction algorithm is proposed. In the algorithm, two methods are proposed, each of which works in one stage. The weighted adaptive noise filtering method (WAF) is proposed for the first stage. The acceleration derivative is used as motion artefact reference and the Pearson correlation coefficient between acceleration and ECG signal is used as a weighting factor. In the second stage, a recursive Hampel filter-based estimation method (RHFBE) is proposed for estimating the ECG signal segments, based on the spatial correlation of the ECG segment component that is obtained from successive ECG signals. Real-World dataset is used to evaluate the effectiveness of the proposed methods compared to the conventional adaptive filter. The results show a promising enhancement in terms of reducing motion artefacts from the ECG signals recorded by a cost-effective single lead ECG sensor during several activities of different subjects.
    Matched MeSH terms: Artifacts
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