Displaying all 16 publications

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  1. Ong P
    ScientificWorldJournal, 2014;2014:943403.
    PMID: 25298971 DOI: 10.1155/2014/943403
    Modification of the intensification and diversification approaches in the recently developed cuckoo search algorithm (CSA) is performed. The alteration involves the implementation of adaptive step size adjustment strategy, and thus enabling faster convergence to the global optimal solutions. The feasibility of the proposed algorithm is validated against benchmark optimization functions, where the obtained results demonstrate a marked improvement over the standard CSA, in all the cases.
  2. Taufiq-Yap, Y. H., Ong, P. S., Zainal, Z.
    MyJurnal
    In this work, 10 mol% yttrium-doped ceria powders, Ce0.9Y0.1O1.95, were synthesised using a new mechanical technique, mechanochemical reaction, in which both impact action and shearing forces were applied for efficient fine grinding, subsequently leading to higher homogeneity of the resultant powders. Ce0.9Y0.1O1.95 prepared using this new technique was systematically compared with a sample of the same prepared using conventional solid-state methodology. X-ray diffraction analysis showed all prepared samples were single phase with a cubic fluorite structure. Generally, Y2O3-doped CeO2 electrolytes prepared by mechanochemical reactions were stable at a lower temperature (1100 °C) compared with a sample of the same synthesised using the conventional solid-state method. Characterisations using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) showed no thermal changes and phase transitions, indicating all materials were thermally stable. The electrical properties of the samples investigated by AC impedance spectroscopy in the temperature range 200–800 ˚C are presented and discussed. Scanning electron microscopy (SEM) was used to study the morphology of the materials. Fine-grained powders with uniform grain-size distribution were obtained from the mechanochemical reaction.
  3. Yeow C, Chin CH, Ong PH
    Med J Malaysia, 1995 Dec;50(4):414-6.
    PMID: 8668066
    Giant cell tumour of bone occurring around the knee is fairly common and can be difficult to manage. We report a case of such tumour involving the distal femur which was successfully treated with complete excision followed by arthrodesis of the knee with a long interlocking intramedullary nail.
  4. Ong P, Jian J, Yin J, Ma G
    PMID: 37451211 DOI: 10.1016/j.saa.2023.123095
    Wavelength selection is crucial to the success of near-infrared (NIR) spectroscopy analysis as it considerably improves the generalization of the multivariate model and reduces model complexity. This study proposes a new wavelength selection method, interval flower pollination algorithm (iFPA), for spectral variable selection in the partial least squares regression (PLSR) model. The proposed iFPA consists of three phases. First, the flower pollination algorithm is applied to search for informative spectral variables, followed by variable elimination. Subsequently, the iFPA performs a local search to determine the best continuous interval spectral variables. The interpretability of the selected variables is assessed on three public NIR datasets (corn, diesel and soil datasets). Performance comparison with other competing wavelength selection methods shows that the iFPA used in conjunction with the PLSR model gives better prediction performance, with the root mean square error of prediction values of 0.0096-0.0727, 0.0015-3.9717 and 1.3388-29.1144 are obtained for various responses in corn, diesel and soil datasets, respectively.
  5. Tan PH, Lui WO, Ong P, Lau LC, Tao M, Chong Y
    Cancer Genet. Cytogenet., 2000 Aug;121(1):61-6.
    PMID: 10958943
    Tumor cytogenetic analysis from 27 patients with breast cancer diagnosed at the Singapore General Hospital revealed complex karyotypic aberrations in 12 cases. The study group comprised 25 women and 2 men, ranging in age from 33 to 78 years (median 52 years). Ethnic distribution consisted of 22 Chinese, 3 Malaysian, and 2 Indian patients. Pathologic assessment disclosed 24 invasive ductal, 2 invasive mucinous, and 1 mixed invasive mucinous and ductal carcinomas. Histologic grading showed 3 grade 1, 10 grade 2, and 12 grade 3 tumors; 2 cancers were not graded, because they had been subjected to prior chemotherapy. Tumor sizes ranged from 1.5 to 10 cm (median 3 cm). Eleven cases were axillary node negative, whereas the remaining 16 node-positive cancers affected as many as 3 nodes in 8 cases and 4 or more nodes in another 8. Twenty cases demonstrated estrogen-receptor positivity, and 8 cases progesterone-receptor positivity. The spectrum of cytogenetic abnormalities involved chromosomes 1, 3, 6, 7, 8, 11, 16, and 17 and ranged from gains and deletions of both long and short arms, trisomy, monosomy, and other rearrangements. There was a trend toward the presence of karyotypic abnormalities in tumors of higher grade.
  6. Kong NC, Asmah J, Lim VK, Ong PH, Adam PA
    Ann Acad Med Singap, 1996 Jul;25(4):609-11.
    PMID: 8893941
    Pyomyositis, purportedly a common tropical infection affecting mainly healthy adults and children, appears to be most uncommon in this region. We report a case of pyomyositis caused by a Methicillin-resistant Staphylococcus aureus (MRSA) in a previously healthy army officer. This case serves to illustrate the difficulty in recognising this disease entity, which is why many cases may have been missed. With the increasing incidence of MRSA nosocomial infections, the emergence of MRSA in a hitherto community-acquired infection poses a major concern especially since intravenous drug abuse and acquired immune deficiency syndrome (AIDS) are on the rise in our country. We hope to inculcate greater awareness of this infection.
  7. Ong P, Chen S, Tsai CY, Chuang YK
    PMID: 33744842 DOI: 10.1016/j.saa.2021.119657
    In this study, near-infrared (NIR) spectroscopy was exploited for non-destructive determination of theanine content of oolong tea. The NIR spectral data (400-2500 nm) were correlated with the theanine level of 161 tea samples using partial least squares regression (PLSR) with different wavelengths selection methods, including the regression coefficient-based selection, uninformative variable elimination, variable importance in projection, selectivity ratio and flower pollination algorithm (FPA). The potential of using the FPA to select the discriminative wavelengths for PLSR was examined for the first time. The analysis showed that the PLSR with FPA method achieved better predictive results than the PLSR with full spectrum (PLSR-full). The developed simplified model using on FPA based on 12 latent variables and 89 selected wavelengths produced R-squared (R2) value and root mean squared error (RMSE) of 0.9542, 0.8794 and 0.2045, 0.3219 for calibration and prediction, respectively. For PLSR-full, the R2 values of 0.9068, 0.8412 and RMSEs of 0.2916, 0.3693, were achieved for calibration and prediction. Also, the optimized model using FPA outperformed other wavelengths selection methods considered in this study. The obtained results indicated the feasibility of FPA to improve the predictability of the PLSR and reduce the model complexity. The nonlinear regression models of support vector machine regression and Gaussian process regression (GPR) were further utilized to evaluate the superiority of using the FPA in the wavelength selection. The results demonstrated that utilizing the wavelength selection method of FPA and nonlinear regression model of GPR could improve the predictive performance.
  8. Ong P, Jian J, Li X, Yin J, Ma G
    PMID: 37804706 DOI: 10.1016/j.saa.2023.123477
    Spectroscopy in the visible and near-infrared region (Vis-NIR) region has proven to be an effective technique for quantifying the chlorophyll contents of plants, which serves as an important indicator of their photosynthetic rate and health status. However, the Vis-NIR spectroscopy analysis confronts a significant challenge concerning the existence of spectral variations and interferences induced by diverse factors. Hence, the selection of characteristic wavelengths plays a crucial role in Vis-NIR spectroscopy analysis. In this study, a novel wavelength selection approach known as the modified regression coefficient (MRC) selection method was introduced to enhance the diagnostic accuracy of chlorophyll content in sugarcane leaves. Experimental data comprising spectral reflectance measurements (220-1400 nm) were collected from sugarcane leaf samples at different growth stages, including seedling, tillering, and jointing, and the corresponding chlorophyll contents were measured. The proposed MRC method was employed to select optimal wavelengths for analysis, and subsequent partial least squares regression (PLSR) and Gaussian process regression (GPR) models were developed to establish the relationship between the selected wavelengths and the measured chlorophyll contents. In comparison to full-spectrum modelling and other commonly employed wavelength selection techniques, the proposed simplified MRC-GPR model, utilizing a subset of 291 selected wavelengths, demonstrated superior performance. The MRC-GPR model achieved higher coefficient of determination of 0.9665 and 0.8659, and lower root mean squared error of 1.7624 and 3.2029, for calibration set and prediction set, respectively. Results showed that the GPR model, a nonlinear regression approach, outperformed the PLSR model.
  9. Ong P, Jian J, Li X, Zou C, Yin J, Ma G
    PMID: 37356390 DOI: 10.1016/j.saa.2023.123037
    The proliferation of pathogenic fungi in sugarcane crops poses a significant threat to agricultural productivity and economic sustainability. Early identification and management of sugarcane diseases are therefore crucial to mitigate the adverse impacts of these pathogens. In this study, visible and near-infrared spectroscopy (380-1400 nm) combined with a novel wavelength selection method, referred to as modified flower pollination algorithm (MFPA), was utilized for sugarcane disease recognition. The selected wavelengths were incorporated into machine learning models, including Naïve Bayes, random forest, and support vector machine (SVM). The developed simplified SVM model, which utilized the MFPA wavelength selection method yielded the best performances, achieving a precision value of 0.9753, a sensitivity value of 0.9259, a specificity value of 0.9524, and an accuracy of 0.9487. These results outperformed those obtained by other wavelength selection approaches, including the selectivity ratio, variable importance in projection, and the baseline method of the flower pollination algorithm.
  10. Ong P, Yeh CW, Tsai IL, Lee WJ, Wang YJ, Chuang YK
    PMID: 37531681 DOI: 10.1016/j.saa.2023.123214
    Consumption of agricultural products with pesticide residue is risky and can negatively affect health. This study proposed a nondestructive method of detecting pesticide residues in chili pepper based on the combination of visible and near-infrared (VIS/NIR) spectroscopy (400-2498 nm) and deep learning modeling. The obtained spectra of chili peppers with two types of pesticide residues (acetamiprid and imidacloprid) were analyzed using a one-dimensional convolutional neural network (1D-CNN). Compared with the commonly used partial least squares regression model, the 1D-CNN approach yielded higher prediction accuracy, with a root mean square error of calibration of 0.23 and 0.28 mg/kg and a root mean square error of prediction of 0.55 and 0.49 mg/kg for the acetamiprid and imidacloprid data sets, respectively. Overall, the results indicate that the combination of the 1D-CNN model and VIS/NIR spectroscopy is a promising nondestructive method of identifying pesticide residues in chili pepper.
  11. Li X, Wang X, Ong P, Yi Z, Ding L, Han C
    Sensors (Basel), 2023 Oct 13;23(20).
    PMID: 37896537 DOI: 10.3390/s23208444
    Dragon fruit (Hylocereus undatus) is a tropical and subtropical fruit that undergoes multiple ripening cycles throughout the year. Accurate monitoring of the flower and fruit quantities at various stages is crucial for growers to estimate yields, plan orders, and implement effective management strategies. However, traditional manual counting methods are labor-intensive and inefficient. Deep learning techniques have proven effective for object recognition tasks but limited research has been conducted on dragon fruit due to its unique stem morphology and the coexistence of flowers and fruits. Additionally, the challenge lies in developing a lightweight recognition and tracking model that can be seamlessly integrated into mobile platforms, enabling on-site quantity counting. In this study, a video stream inspection method was proposed to classify and count dragon fruit flowers, immature fruits (green fruits), and mature fruits (red fruits) in a dragon fruit plantation. The approach involves three key steps: (1) utilizing the YOLOv5 network for the identification of different dragon fruit categories, (2) employing the improved ByteTrack object tracking algorithm to assign unique IDs to each target and track their movement, and (3) defining a region of interest area for precise classification and counting of dragon fruit across categories. Experimental results demonstrate recognition accuracies of 94.1%, 94.8%, and 96.1% for dragon fruit flowers, green fruits, and red fruits, respectively, with an overall average recognition accuracy of 95.0%. Furthermore, the counting accuracy for each category is measured at 97.68%, 93.97%, and 91.89%, respectively. The proposed method achieves a counting speed of 56 frames per second on a 1080ti GPU. The findings establish the efficacy and practicality of this method for accurate counting of dragon fruit or other fruit varieties.
  12. Ong P, Jian J, Li X, Zou C, Yin J, Ma G
    PMID: 39180971 DOI: 10.1016/j.saa.2024.125001
    Utilizing visible and near-infrared (Vis-NIR) spectroscopy in conjunction with chemometrics methods has been widespread for identifying plant diseases. However, a key obstacle involves the extraction of relevant spectral characteristics. This study aimed to enhance sugarcane disease recognition by combining convolutional neural network (CNN) with continuous wavelet transform (CWT) spectrograms for spectral features extraction within the Vis-NIR spectra (380-1400 nm) to improve the accuracy of sugarcane diseases recognition. Using 130 sugarcane leaf samples, the obtained one-dimensional CWT coefficients from Vis-NIR spectra were transformed into two-dimensional spectrograms. Employing CNN, spectrogram features were extracted and incorporated into decision tree, K-nearest neighbour, partial least squares discriminant analysis, and random forest (RF) calibration models. The RF model, integrating spectrogram-derived features, demonstrated the best performance with an average precision of 0.9111, sensitivity of 0.9733, specificity of 0.9791, and accuracy of 0.9487. This study may offer a non-destructive, rapid, and accurate means to detect sugarcane diseases, enabling farmers to receive timely and actionable insights on the crops' health, thus minimizing crop loss and optimizing yields.
  13. Sreekar R, Katabuchi M, Nakamura A, Corlett RT, Slik JWF, Fletcher C, et al.
    R Soc Open Sci, 2018 Sep;5(9):181168.
    PMID: 30839691 DOI: 10.1098/rsos.181168
    The relationship between β-diversity and latitude still remains to be a core question in ecology because of the lack of consensus between studies. One hypothesis for the lack of consensus between studies is that spatial scale changes the relationship between latitude and β-diversity. Here, we test this hypothesis using tree data from 15 large-scale forest plots (greater than or equal to 15 ha, diameter at breast height ≥ 1 cm) across a latitudinal gradient (3-30o) in the Asia-Pacific region. We found that the observed β-diversity decreased with increasing latitude when sampling local tree communities at small spatial scale (grain size ≤0.1 ha), but the observed β-diversity did not change with latitude when sampling at large spatial scales (greater than or equal to 0.25 ha). Differences in latitudinal β-diversity gradients across spatial scales were caused by pooled species richness (γ-diversity), which influenced observed β-diversity values at small spatial scales, but not at large spatial scales. Therefore, spatial scale changes the relationship between β-diversity, γ-diversity and latitude, and improving sample representativeness avoids the γ-dependence of β-diversity.
  14. Russo SE, McMahon SM, Detto M, Ledder G, Wright SJ, Condit RS, et al.
    Nat Ecol Evol, 2021 Feb;5(2):174-183.
    PMID: 33199870 DOI: 10.1038/s41559-020-01340-9
    Resource allocation within trees is a zero-sum game. Unavoidable trade-offs dictate that allocation to growth-promoting functions curtails other functions, generating a gradient of investment in growth versus survival along which tree species align, known as the interspecific growth-mortality trade-off. This paradigm is widely accepted but not well established. Using demographic data for 1,111 tree species across ten tropical forests, we tested the generality of the growth-mortality trade-off and evaluated its underlying drivers using two species-specific parameters describing resource allocation strategies: tolerance of resource limitation and responsiveness of allocation to resource access. Globally, a canonical growth-mortality trade-off emerged, but the trade-off was strongly observed only in less disturbance-prone forests, which contained diverse resource allocation strategies. Only half of disturbance-prone forests, which lacked tolerant species, exhibited the trade-off. Supported by a theoretical model, our findings raise questions about whether the growth-mortality trade-off is a universally applicable organizing framework for understanding tropical forest community structure.
  15. Wills C, Wang B, Fang S, Wang Y, Jin Y, Lutz J, et al.
    PLoS Comput Biol, 2021 Apr;17(4):e1008853.
    PMID: 33914731 DOI: 10.1371/journal.pcbi.1008853
    When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands' physical similarity, members of species that had dispersed to them recently were beginning to diverge from each other. He postulated that these divergences must have resulted primarily from interactions with sets of other species that had also diverged across these otherwise similar islands. By extrapolation, if Darwin is correct, such complex interactions must be driving species divergences across all ecosystems. However, many current general ecological theories that predict observed distributions of species in ecosystems do not take the details of between-species interactions into account. Here we quantify, in sixteen forest diversity plots (FDPs) worldwide, highly significant negative density-dependent (NDD) components of both conspecific and heterospecific between-tree interactions that affect the trees' distributions, growth, recruitment, and mortality. These interactions decline smoothly in significance with increasing physical distance between trees. They also tend to decline in significance with increasing phylogenetic distance between the trees, but each FDP exhibits its own unique pattern of exceptions to this overall decline. Unique patterns of between-species interactions in ecosystems, of the general type that Darwin postulated, are likely to have contributed to the exceptions. We test the power of our null-model method by using a deliberately modified data set, and show that the method easily identifies the modifications. We examine how some of the exceptions, at the Wind River (USA) FDP, reveal new details of a known allelopathic effect of one of the Wind River gymnosperm species. Finally, we explore how similar analyses can be used to investigate details of many types of interactions in these complex ecosystems, and can provide clues to the evolution of these interactions.
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