Displaying publications 1 - 20 of 67 in total

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  1. Fulltext ON NUMERICAL METHODS FOR SECOND-ORDER NON-LINEAR ORDINARY DIFFERENTIAL EQUATIONS (ODEs): A REDUCTION TO A SYSTEM OF FIRST-ORDER ODEs
    Loy Kak Choon, Puteri Nurul Fatihah binti Mohamad Azli
    UMT Journal of Undergraduate Research, 2019;1(4):1-8.
    MyJurnal
    2nd-order ODEs can be found in many applications, e.g., motion of pendulum, vibrating springs, etc. We first convert the 2nd-order nonlinear ODEs to a system of 1st-order ODEs which is easier to deal with. Then, Adams-Bashforth (AB) methods are used to solve the resulting system of 1st-order ODE. AB methods are chosen since they are the explicit schemes and more efficient in terms of shorter computational time. However, the step size is more restrictive since these methods are conditionally stable. We find two test cases (one test problem and one manufactured solution) to be used to validate the AB methods. The exact solution for both test cases are available for the error and convergence analysis later on. The implementation of 1st-, 2nd- and 3rd-order AB methods are done using Octave. The error was computed to retrieve the order of convergence numerically and the CPU time was recorded to analyze their efficiency.
    Matched MeSH terms: Causality
  2. Fulltext Quantifying 'causality' in complex systems: understanding transfer entropy
    Abdul Razak F, Jensen HJ
    PLoS One, 2014;9(6):e99462.
    PMID: 24955766 DOI: 10.1371/journal.pone.0099462
    'Causal' direction is of great importance when dealing with complex systems. Often big volumes of data in the form of time series are available and it is important to develop methods that can inform about possible causal connections between the different observables. Here we investigate the ability of the Transfer Entropy measure to identify causal relations embedded in emergent coherent correlations. We do this by firstly applying Transfer Entropy to an amended Ising model. In addition we use a simple Random Transition model to test the reliability of Transfer Entropy as a measure of 'causal' direction in the presence of stochastic fluctuations. In particular we systematically study the effect of the finite size of data sets.
    Matched MeSH terms: Causality*
  3. Fulltext Assessment of DSM Based on Radiometric Transformation of UAV Data
    Chaudhry MH, Ahmad A, Gulzar Q, Farid MS, Shahabi H, Al-Ansari N
    Sensors (Basel), 2021 Feb 27;21(5).
    PMID: 33673425 DOI: 10.3390/s21051649
    Unmanned Aerial Vehicle (UAV) is one of the latest technologies for high spatial resolution 3D modeling of the Earth. The objectives of this study are to assess low-cost UAV data using image radiometric transformation techniques and investigate its effects on global and local accuracy of the Digital Surface Model (DSM). This research uses UAV Light Detection and Ranging (LIDAR) data from 80 meters and UAV Drone data from 300 and 500 meters flying height. RAW UAV images acquired from 500 meters flying height are radiometrically transformed in Matrix Laboratory (MATLAB). UAV images from 300 meters flying height are processed for the generation of 3D point cloud and DSM in Pix4D Mapper. UAV LIDAR data are used for the acquisition of Ground Control Points (GCP) and accuracy assessment of UAV Image data products. Accuracy of enhanced DSM with DSM generated from 300 meters flight height were analyzed for point cloud number, density and distribution. Root Mean Square Error (RMSE) value of Z is enhanced from ±2.15 meters to 0.11 meters. For local accuracy assessment of DSM, four different types of land covers are statistically compared with UAV LIDAR resulting in compatibility of enhancement technique with UAV LIDAR accuracy.
    Matched MeSH terms: Causality
  4. Fulltext Hybrid discrete hopfield neural network based modified clonal selection algorithm for VLSI circuit verification
    Sathasivam, Saratha, Mustafa Mamat, Mohd Shareduwan Mohd Kasihmuddin, Mohd. Asyraf Mansor
    Pertanika Journal of Science & Technology, 2020;28(1):227-243.
    MyJurnal
    Clonal selection algorithm and discrete Hopfield neural network are extensively employed for solving higher-order optimization problems ranging from the constraint satisfaction problem to complex pattern recognition. The modified clonal selection algorithm is a comprehensive and less iterative immune-inspired searching algorithm, utilized to search for the correct combination of instances for Very large-scale integrated (VLSI) circuit structure. In this research, the VLSI circuit framework consists of Boolean 3-Satisfiability instances with the different complexities and number of transistors are considered. Hence, a hybrid modified clonal selection algorithm with discrete Hopfield neural network is well developed to optimize the configuration of VLSI circuits with different number of electronic components such as transistors as the instances. Therefore, the performance of the developed hybrid model was assessed experimentally with the standard models, HNNVLSI-3SATES and HNNVLSI-3SATGA in term of circuit accuracy, sensitivity, robustness and runtime to complete the verification process. The results have demonstrated the developed model, HNNVLSI-3SATCSA produced a minimum error (consistently approaching 0), better accuracy (more than 80%) and faster computational time (less than 125 seconds) against changes in the complexity in term of the number of transistors. Furthermore, the developed hybrid model is able to minimize the computational burden and configurational noises for the variant of VLSI circuits.
    Matched MeSH terms: Causality
  5. Fulltext An integration based optimization approach (ABC and PSO) for parameter estimation in BLRP model for disaggregating daily rainfall
    Zulkarnain Hassan
    Pertanika Journal of Science & Technology, 2020;28(1):385-402.
    MyJurnal
    Fine resolution (hourly rainfall) of rainfall series for various hydrological systems is widely used. However, observed hourly rainfall records may lack in the quality of data and resulting difficulties to apply it. The utilization of Bartlett-Lewis rectangular pulse (BLRP) is proposed to overcome this limitation. The calibration of this model is regarded as a difficult task due to the existence of intensive estimation of parameters. Global optimization algorithms, named as artificial bee colony (ABC) and particle swarm optimization (PSO) were introduced to overcome this limitation. The issues and ability of each optimization in the calibration procedure were addressed. The results showed that the BLRP model with ABC was able to reproduce well for the rainfall characteristics at hourly and daily rainfall aggregation, similar to PSO. However, the fitted BLRP model with PSO was able to reproduce the rainfall extremes better as compared to ABC.
    Matched MeSH terms: Causality
  6. Fulltext Mitigating Effect of Psychological Capital on Employees' Withdrawal Behavior in the Presence of Job Attitudes: Evidence From Five-Star Hotels in Malaysia
    Yan Z, Mansor ZD, Choo WC, Abdullah AR
    Front Psychol, 2021;12:617023.
    PMID: 33868086 DOI: 10.3389/fpsyg.2021.617023
    High turnover rate is one of the striking features of the hotel industry and one of the most significant challenges. High turnover rate causes substantial costs for recruitment, selection and training in hotels, on the other hand, it also leads to negative consequences such as the decline of organizational performance and service quality. Thus, it is necessary to search for the root causes of turnover and put forward solutions. This study was designed to examine the impact of psychological capital (PsyCap), organizational commitment (OC), and job satisfaction (JS) on turnover intention among hotel employees. Additionally, it aimed to test the mediating roles of job satisfaction (JS) and organizational commitment (OC). The data were obtained from 228 hotel customer-contact employees with a time lag of two weeks in three waves in Kuala Lumpur based on convenience sampling. A series of structural equation modeling analyses were utilized to investigate hypothesized relationships. The results reveal that there exists a significant and negative impact of PsyCap on employees' turnover intention and this correlation is partially mediated through two job attitudes. That is to say, to retain hotel talents, five-star hotel management should take proper measures to help employees obtain and maintain positive psychological resources such as PsyCap, on the other hand, how to cultivate positive job attitudes and strengthen their sense of identification and belonging for their organizations is supposed to be more focused on.
    Matched MeSH terms: Causality
  7. Fulltext A case of unrecognized psychogenic polydipsia
    Seng-Choi Chong, Normala Ibrahim
    Malaysian Journal of Medicine and Health Sciences, 2020;16(3):337-339.
    MyJurnal
    Psychogenic polydipsia is prevalent among people with schizophrenia. Although its pathophysiology is relatively unknown, it causes life threatening complications due to acute or severe hyponatraemia.. This report illustrates a patient with schizophrenia who had unrecognized psychogenic polydipsia and developed severe complication. It also highlights the clinical salience of its management.
    Matched MeSH terms: Causality
  8. Fulltext Cube polygon: a new modified Euler method to improve electric circuit efficiency
    Nurhafizah Moziyana Mohd Yusop, Nooraida Samsudin, Nooraida Samsudin, Anis Shahida Mokhta, Siti Rohaidah Ahmad, Mohd Fahmi Mohammad Amran, et al.
    ZULFAQAR International Journal of Defence Science, Engineering & Technology, 2020;3(1):8-14.
    MyJurnal
    Euler method is a numerical order process for solving problems with the Ordinary Differential Equation (ODE). It is a fast and easy way. While Euler offers a simple procedure for solving ODEs, problems such as complexity, processing time and accuracy have driven others to use more sophisticated methods. Improvements to the Euler method have attracted much attention resulting in numerous modified Euler methods. This paper proposes Cube Polygon, a modified Euler method with improved accuracy and complexity. In order to demonstrate the accuracy and easy implementation of the proposed method, several examples are presented. Cube Polygon’s performance was compared to Polygon’s scheme and evaluated against exact solutions using SCILAB. Results indicate that not only Cube Polygon has produced solutions that are close to identical solutions for small step sizes, but also for higher step sizes, thus generating more accurate results and decrease complexity. Also known in this paper is the general of the RL circuit due to the ODE problem.
    Matched MeSH terms: Causality
  9. Influencing preferences for different types of causal explanation of complex events
    Klein G, Rasmussen L, Lin MH, Hoffman RR, Case J
    Hum Factors, 2014 Dec;56(8):1380-400.
    PMID: 25509820
    We examined preferences for different forms of causal explanations for indeterminate situations. Background: Klein and Hoffman distinguished several forms of causal explanations for indeterminate, complex situations: single-cause explanations, lists of causes, and explanations that interrelate several causes. What governs our preferences for single-cause (simple) versus multiple- cause (complex) explanations?
    Matched MeSH terms: Causality*
  10. Effect of Isolated Medial Patellofemoral Ligament Reconstruction in Patellofemoral Instability Regardless of Predisposing Factors
    Lee JI, Jaffar MSA, Choi HG, Kim TW, Lee YS
    J Knee Surg, 2022 Feb;35(3):299-307.
    PMID: 32659817 DOI: 10.1055/s-0040-1713898
    The purpose of this study was to evaluate the outcomes of isolated medial patellofemoral ligament (MPFL) reconstruction, regardless of the presence of predisposing factors. A total of 21 knees that underwent isolated MPFL reconstruction from March 2014 to August 2017 were included in this retrospective series. Radiographs of the series of the knee at flexion angles of 20, 40, and 60 degrees were acquired. The patellar position was evaluated using the patellar tilt angle, sulcus angle, congruence angle (CA), and Caton-Deschamps and Blackburne-Peel ratios. To evaluate the clinical outcome, the preoperative and postoperative International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales were analyzed. To evaluate the postoperative outcomes based on the predisposing factors, the results were separately analyzed for each group. Regarding radiologic outcomes, 20-degree CA was significantly reduced from 10.37 ± 5.96° preoperatively to -0.94 ± 4.11° postoperatively (p = 0.001). In addition, regardless of the predisposing factors, delta values of pre- and postoperation of 20-degree CA were not significantly different in both groups. The IKDC score improved from 53.71 (range: 18-74) preoperatively to 94.71 (range: 86-100) at the last follow-up (p = 0.004), and the Lysholm score improved from 54.28 (range: 10-81) preoperatively to 94.14 (range: 86-100) at the last follow-up (p = 0.010). Isolated MPFL reconstruction provides a safe and effective treatment for patellofemoral instability, even in the presence of mild predisposing factors, such as trochlear dysplasia, increased patella height, increased TT-TG distance, or valgus alignment. This is a Level 4, case series study.
    Matched MeSH terms: Causality
  11. Novice driver crashes: The relation between putative causal factors, countermeasures, real world implementations, and policy - A case study in simple, scalable solutions
    Fisher DL, Agrawal R, Divekar G, Hamid MA, Krishnan A, Mehranian H, et al.
    Accid Anal Prev, 2024 Apr;198:107397.
    PMID: 38271896 DOI: 10.1016/j.aap.2023.107397
    Novice drivers are at a greatly inflated risk of crashing. This led in the 20th century to numerous attempts to develop training programs that could reduce their crash risk. Yet, none proved effective. Novice drivers were largely considered careless, not clueless. This article is a case study in the United States of how a better understanding of the causes of novice driver crashes led to training countermeasures targeting teen driving behaviors with known associations with crashes. These effects on behaviors were large enough and long-lasting enough to convince insurance companies to develop training programs that they offered around the country to teen drivers. The success of the training programs at reducing the frequency of behaviors linked to crashes also led to several large-scale evaluations of the effect of the training programs on actual crashes. A reduction in crashes was observed. The cumulative effect has now led to state driver licensing agencies considering as a matter of policy both to include items testing the behaviors linked to crashes on licensing exams and to require training on safety critical behaviors. The effort has been ongoing for over a quarter century and is continuing. The case study highlights the critical elements that made it possible to move from a paradigm shift in the understanding of crash causes to the development and evaluation of crash countermeasures, to the implementation of those crash countermeasures, and to subsequent policy changes at the state and federal level. Key among these elements is the development of simple, scalable solutions.
    Matched MeSH terms: Causality
  12. Skin eruption induced by dieting - an underdiagnosed skin disease in Malaysia
    Goh SW, Adawiyah J, Md Nor N, Yap F, Ch'ng P, Chang CC
    Malays Fam Physician, 2019;14(1):42-46.
    PMID: 31289632
    Prurigo pigmentosa is an inflammatory dermatosis characterized by a pruritic, symmetrically distributed erythematous papular or papulo-vesicular eruption on the trunk arranged in a reticulated pattern that resolves with hyperpigmentation. It is typically non-responsive to topical or systemic steroid therapy. The exact etiology is unknown, but it is more commonly described in the Far East countries. Dietary change is one of the predisposing factors. We report on nine young adult patients with prurigo pigmentosa, among whom five were on ketogenic diets prior to the onset of the eruptions. All cases resolved with oral doxycycline with no recurrence. We hope to improve the awareness of this uncommon skin condition among general practitioners and physicians so that disfiguring hyperpigmentation due to delayed diagnosis and treatment can be avoided.
    Matched MeSH terms: Causality
  13. Fulltext Chikungunya and alternative treatment from natural products: a review
    Syuhadaratul Aini Mohamat, Nor Fazila Che Mat, Najmo Ibrahim Barkhadle2, Tuan Nur Akmalina Mat Jusoh, Rafidah Hanim Shueb
    Malaysian Journal of Medicine and Health Sciences, 2020;16(1):304-311.
    MyJurnal
    Chikungunya is an infection caused by chikungunya virus which at present has spread to new countries and con- tinents. Chikungunya is associated with self-limiting and non-fatal infection in the past. However, in recent times, increased severity of the disease has been reported resulting in health and economic burden. The threat and bur- den of chikungunya would grow in future in the absence of specific antiviral or vaccine to control or eliminate the infection. This review discusses chikungunya in general including transmission of its etiological agent and clinical manifestations of the disease. Subsequently, management and treatment of chikungunya virus will be reviewed with particular emphasis on natural products or their active compounds with potential anti-chikungunya virus activities.
    Matched MeSH terms: Causality
  14. Fulltext The impacts of climate variability on cholera cases in Malaysia
    Noor Artika Hassan, Hashim JH, Wan Puteh SE, Wan Mahiyuddin WR, Faisal MS
    IIUM Medical Journal Malaysia, 2020;19(1):75-83.
    MyJurnal
    Introduction: Altered weather patterns and changes in precipitation, temperature and humidity resulting
    from climate change could affect the distribution and incidence of cholera. This study is to quantify climateinduced increase in morbidity rates of cholera. Material and Methods: Monthly cholera cases and monthly
    temperature, precipitation, and relative humidity data from 2004 to 2014 were obtained from the Malaysian
    Ministry of Health and Malaysian Meteorological Department, respectively. Poisson generalized linear models
    were developed to quantify the relationship between meteorological parameters and the number of reported
    cholera cases. Results: The findings revealed that the total number of cholera cases in Malaysia during the 11
    year study period was 3841 cases with 32 deaths. Out of these, 45.1% of the cases were among children below
    12 years old and 75% of the cases were from Sabah. Temperature and precipitation gave significant impact on
    the cholera cases in Sabah, (p
    Matched MeSH terms: Causality
  15. Fulltext Bilateral neonatal breast abscess in a well-appearing neonate
    Muhammad Yusoff Mohd Ramdzan, Jamil Aiman Mohd Baharuddin, Nordiyana Azmi, Noraida Ramli, Nor Rosidah Ibrahim, Rostenberghe, Hans Van
    Malaysian Journal of Paediatrics and Child Health, 2019;25(1):27-29.
    MyJurnal
    Neonatal mastitis and abscess are rare and most often unilateral. Neonatal breast massage for physiological breast hypertrophy is suspected to be a predisposing factor in the case reported here: a 14-day-old neonate with bilateral neonatal breast abscess, treated effectively with intravenous cloxacillin and surgical aspiration.
    Matched MeSH terms: Causality
  16. The utility of the Laplace effect size prior distribution in Bayesian fine-mapping studies
    Walters K, Cox A, Yaacob H
    Genet Epidemiol, 2021 Jun;45(4):386-401.
    PMID: 33410201 DOI: 10.1002/gepi.22375
    The Gaussian distribution is usually the default causal single-nucleotide polymorphism (SNP) effect size prior in Bayesian population-based fine-mapping association studies, but a recent study showed that the heavier-tailed Laplace prior distribution provided a better fit to breast cancer top hits identified in genome-wide association studies. We investigate the utility of the Laplace prior as an effect size prior in univariate fine-mapping studies. We consider ranking SNPs using Bayes factors and other summaries of the effect size posterior distribution, the effect of prior choice on credible set size based on the posterior probability of causality, and on the noteworthiness of SNPs in univariate analyses. Across a wide range of fine-mapping scenarios the Laplace prior generally leads to larger 90% credible sets than the Gaussian prior. These larger credible sets for the Laplace prior are due to relatively high prior mass around zero which can yield many noncausal SNPs with relatively large Bayes factors. If using conventional credible sets, the Gaussian prior generally yields a better trade off between including the causal SNP with high probability and keeping the set size reasonable. Interestingly when using the less well utilised measure of noteworthiness, the Laplace prior performs well, leading to causal SNPs being declared noteworthy with high probability, whilst generally declaring fewer than 5% of noncausal SNPs as being noteworthy. In contrast, the Gaussian prior leads to the causal SNP being declared noteworthy with very low probability.
    Matched MeSH terms: Causality
  17. Fulltext Review on prophylactic antibiotics for dental patients with prosthetic joints
    Chai WL, Yong CK, Ngeow WC
    Ann Dent, 2003;10(1):22-26.
    MyJurnal
    Most prosthetic joint infections originate from wound contamination or haematogenous seeding from distant sites of infection. Bacteraemia may follow dental treatment but there is little evidence of it related to prosthetic joint infection. Nevertheless, controversy continues with regards to the effect of dental treatment in patients with prosthetic joints. This article reviews current English literature regarding the use of antibiotic prophylaxis in the dental management of patients with prosthetic joints. Routine antibiotic prophylaxis is not recommended for every patient with prosthetic joints when receiving dental treatments. However, antibiotic prophylaxis may be prescribed for high-risk groups with predisposing factors to infection when undergoing dental treatment with high risk of bacteraemia.
    Matched MeSH terms: Causality
  18. Fulltext Koro-like symptoms with associated erectile dysfunction in a Rohingya refugee
    Abdullah KHA, Wahab S
    ASEAN Journal of Psychiatry, 2012;13(2):221-223.
    MyJurnal
    This case report highlights Koro-like symptoms with erectile dysfunction.
    Methods: We report a case of a Rohingya refugee who presented with Koro-like symptoms associated with erectile dysfunction and severe religious guilt.
    Results: Sexual dysfunction, i.e. erectile dysfunction may be a predisposing factor for a Koro incidence. Religious issues complicated by superstitious beliefs pose a treatment challenge.
    Conclusion: Treating patient with sexual dysfunction should involve exploring and addressing patient's conflicts to avoid worsening of symptoms. As this case illustrates, severe anxiety can present with Koro-like symptoms.
    Matched MeSH terms: Causality
  19. Fulltext Down syndrome and Patau syndrome in the same sibship: random or not?
    Foong Eva, Hasliani Hassan, Azizah Othman, Ilunihayati Ibrahim, Nazihah Mohd Yunus, Siti Mariam Ismail, et al.
    Malaysian Journal of Paediatrics and Child Health, 2017;23(2):0-0.
    MyJurnal
    Objectives: Chromosomal abnormalities especially aneuploidies are the most common etiology for pregnancy loss. Trisomy 13, trisomy 18 and trisomy 21 are the most common chromosome autosomal aneuploidies with trisomy 21 (Down syndrome) being the most common chromosomal abnormality among liveborn infants. In previous reports, we noted that the recurrence of these aneuploidies in some families may not occur by chance alone.

    Methods: Extraction of relevant data from review of medical case notes of a young couple with two offspring with Down syndrome (DS) and Patau syndrome.

    Results: A family history of DS is a predisposing factor for both DS and other types of aneuploidy. Certain instances of non-disjunction error are not random.

    Conclusion: As the maternal age was not advanced in both pregnancies, there is a possibility that the recurrent aneuploidy in this family may not be accounted by chance alone. The risk of having subsequent affected pregnancy cannot be ignored in this family and prenatal diagnosis is strongly recommended in the subsequent pregnancy.
    Matched MeSH terms: Causality
  20. Prevalence, Causes and Severity of Medication Administration Errors in the Neonatal Intensive Care Unit: A Systematic Review and Meta-Analysis
    Henry Basil J, Premakumar CM, Mhd Ali A, Mohd Tahir NA, Mohamed Shah N
    Drug Saf, 2022 Dec;45(12):1457-1476.
    PMID: 36192535 DOI: 10.1007/s40264-022-01236-6
    INTRODUCTION: Neonates are at greater risk of preventable adverse drug events as compared to children and adults.

    OBJECTIVE: This study aimed to estimate and critically appraise the evidence on the prevalence, causes and severity of medication administration errors (MAEs) amongst neonates in Neonatal Intensive Care Units (NICUs).

    METHODS: A systematic review and meta-analysis was conducted by searching nine electronic databases and the grey literature for studies, without language and publication date restrictions. The pooled prevalence of MAEs was estimated using a random-effects model. Data on error causation were synthesised using Reason's model of accident causation.

    RESULTS: Twenty unique studies were included. Amongst direct observation studies reporting total opportunity for errors as the denominator for MAEs, the pooled prevalence was 59.3% (95% confidence interval [CI] 35.4-81.3, I2 = 99.5%). Whereas, the non-direct observation studies reporting medication error reports as the denominator yielded a pooled prevalence of 64.8% (95% CI 46.6-81.1, I2 = 98.2%). The common reported causes were error-provoking environments (five studies), while active failures were reported by three studies. Only three studies examined the severity of MAEs, and each utilised a different method of assessment.

    CONCLUSIONS: This is the first comprehensive systematic review and meta-analysis estimating the prevalence, causes and severity of MAEs amongst neonates. There is a need to improve the quality and reporting of studies to produce a better estimate of the prevalence of MAEs amongst neonates. Important targets such as wrong administration-technique, wrong drug-preparation and wrong time errors have been identified to guide the implementation of remedial measures.

    Matched MeSH terms: Causality
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